JP3708536B1 - Refrigeration cycle apparatus and control method thereof - Google Patents

Abstract

In a refrigeration cycle apparatus using an expander, an optimum high pressure side pressure is maintained even if there is a constant density ratio constraint, and the refrigeration cycle operation is performed without reducing the operation efficiency and capacity in various operation ranges. Is possible.
A refrigeration cycle apparatus includes a compression mechanism, an expansion mechanism, a drive source for driving the compression mechanism connected to the expansion mechanism by a single shaft, and a refrigerant discharged from the compression mechanism. A radiator 2 that cools the refrigerant, an evaporator 5 that heats the refrigerant flowing out of the expansion mechanism 3, a bypass passage 10 that bypasses the expansion mechanism 3, a bypass valve 11 provided on the bypass passage 10, and expansion A pre-reducing valve 12 for depressurizing the refrigerant flowing into the mechanism 3 and an operating device 21 for controlling the bypass valve 11 and the pre-reducing valve 12 are provided. By operating the opening degree of the valve 12 and adjusting it to a desired high pressure side pressure, efficient operation over a wide range is possible.
[Selection] Figure 1

Description

  The present invention relates to a refrigeration cycle apparatus including an expander and a control method thereof.

Ozone depletion and is zero, and global warming potential is also much smaller compared to CFCs, carbon dioxide (hereinafter, CO of ₂₎ Although the refrigeration cycle apparatus using the refrigerant is focused in recent years, CO ₂ refrigerant The critical temperature is as low as 31.06 ° C., and when a temperature higher than this temperature is used, the CO ₂ refrigerant is condensed on the high pressure side (compressor outlet to radiator to decompressor inlet) of the refrigeration cycle apparatus. It becomes a supercritical state that does not occur, and the operating efficiency (COP) of the refrigeration cycle apparatus is reduced as compared with the conventional refrigerant. Therefore, in a refrigeration cycle apparatus using a CO ₂ refrigerant, means for improving COP is important.
As such means, there has been proposed a refrigeration cycle in which an expander is provided instead of a decompressor, and pressure energy during expansion is recovered as power. Here, in a refrigeration cycle apparatus having a structure in which a positive displacement compressor and an expander are connected to one shaft, VC / VE (design volume ratio) is given by assuming that the cylinder volume of the compressor is VC and the cylinder volume of the expander is VE. The ratio of the volume circulation amount flowing through each of the compressor and the expander is determined. If the density of the refrigerant at the outlet of the evaporator (refrigerant flowing into the compressor) is DC and the density of the refrigerant at the outlet of the radiator (refrigerant flowing into the expander) is DE, the mass circulation amount flowing through each of the compressor and the expander Therefore, the relationship of “VC × DC = VE × DE”, that is, “VC / VE = DE / DC” is established. Since VC / VE (design volume ratio) is a constant determined at the time of device design, the refrigeration cycle tries to balance so that DE / DC (density ratio) is always constant. (Hereafter, this is referred to as “constant density ratio constant”.)
However, the usage conditions of the refrigeration cycle device are not necessarily constant. Therefore, if the design volume ratio assumed at the time of design and the density ratio in the actual operating state are different, the best condition is due to the “constant density ratio constraint”. It becomes difficult to adjust to the high pressure side pressure.
Therefore, a configuration and a control method have been proposed in which a bypass flow path for bypassing the expander is provided and the amount of refrigerant flowing into the expander is controlled to adjust to the best high pressure side pressure (for example, Patent Document 1 and Patent). Reference 2).
JP 2000-234814 A JP 2001-116371 A

However, in the above-mentioned patent document, when the density ratio in the actual operation state is smaller than the design volume ratio, the configuration can be adjusted to the best high pressure side pressure by flowing the refrigerant through the bypass flow path that bypasses the expander. In the case where the density ratio in the actual operation state is larger than the design volume ratio, there is no description about the configuration and the control method that can be adjusted to the best high pressure side pressure. It also does not describe how to set the design volume ratio value.
Further, even when the density ratio in the actual operation state is smaller than the design volume ratio, the amount of refrigerant flowing through the bypass channel cannot be increased beyond a certain level, that is, the bypass valve provided on the bypass channel is opened. There is no description of what to do if the degree is at its maximum. Therefore, when the density ratio in the actual operation state is larger than the design volume ratio or when the opening of the bypass valve becomes maximum, the refrigeration cycle apparatus cannot be adjusted to the best high-pressure side pressure. There has been a problem that the driving efficiency of the vehicle is reduced.

Therefore, the present invention provides a configuration of a refrigeration cycle apparatus that can be adjusted to the best high-pressure side pressure and a control method thereof, regardless of whether the density ratio in an actual operating state is larger or smaller than the design volume ratio, and the refrigeration cycle apparatus It aims at improving the operation efficiency (COP) of the.
It is another object of the present invention to provide a refrigeration cycle apparatus having a design volume ratio that enables efficient operation in various operating conditions.

A refrigeration cycle apparatus according to a first aspect of the present invention includes a radiator that cools a refrigerant discharged from the compression mechanism, and a expansion mechanism that connects a compression mechanism, an expansion mechanism, and a drive source to a single shaft. In the refrigeration cycle apparatus including an evaporator for heating the refrigerant flowing out from the bypass passage, the bypass passage bypassing the expansion mechanism, the bypass valve provided on the bypass passage, and the refrigerant flowing into the expansion mechanism is decompressed a pre reducing valve which comprises a control Gosuru manipulator operation between said bypass valve said pre reducing valve, the operating device is, the opening degree of said bypass valve said pre reducing valve, the refrigeration cycle apparatus The high pressure side pressure is adjusted by changing the discharge temperature or the degree of superheat .
According to a second aspect of the present invention, there is provided a refrigeration cycle apparatus according to the present invention, in which a compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, and a radiator that cools the refrigerant discharged from the compression mechanism, and the expansion mechanism. In the refrigeration cycle apparatus including an evaporator for heating the refrigerant flowing out from the bypass passage, the bypass passage bypassing the expansion mechanism, the bypass valve provided on the bypass passage, the operation of the bypass valve , and the drive source comprising a number of revolutions and the braking Gosuru manipulator, the manipulator is, a rotational speed of the driving source and the opening degree of the bypass valve is changed based on the discharge temperature or superheat of the refrigeration cycle apparatus Thus, the high pressure side pressure is adjusted .
According to a third aspect of the present invention, there is provided a refrigeration cycle apparatus according to the present invention, wherein a compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, a radiator that cools the refrigerant discharged from the compression mechanism, and the expansion mechanism. In a refrigeration cycle apparatus comprising an evaporator that heats the refrigerant that has flowed out of, a bypass passage that bypasses the expansion mechanism, a bypass valve provided on the bypass passage, a fan that blows air to the evaporator, and a rotational speed and braking Gosuru manipulator of the fan and the bypass valve, wherein the operating device has a rotation speed of the the opening of the bypass valve fan, the discharge temperature or superheat of the refrigeration cycle apparatus The high pressure side pressure is adjusted by changing based on the above.
According to a fourth aspect of the present invention, there is provided a refrigeration cycle apparatus according to the present invention, wherein a compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, a radiator that cools the refrigerant discharged from the compression mechanism, and the expansion mechanism. In the refrigeration cycle apparatus comprising an evaporator for heating the refrigerant flowing out of the refrigerant, the design volume ratio of the compression mechanism and the expansion mechanism is set so that the outlet refrigerant of each of the radiator and the evaporator in the operating state of the refrigeration cycle apparatus. It is characterized by substantially matching with the largest value of the density ratio.
According to a fifth aspect of the present invention, there is provided a refrigeration cycle apparatus of the present invention, in which a compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, and a radiator that cools the refrigerant discharged from the compression mechanism, and the expansion mechanism In the refrigeration cycle apparatus provided with an evaporator for heating the refrigerant flowing out from the refrigerant, the design volume ratio of the compression mechanism and the expansion mechanism is the operating state of the refrigeration cycle apparatus where the refrigerant density at the outlet of the radiator is the largest. The ratio of the outlet refrigerant density of each of the radiator and the evaporator is substantially the same.
A refrigeration cycle apparatus according to a sixth aspect of the present invention includes a radiator that couples a compression mechanism, an expansion mechanism, and a drive source to a single shaft, cools the refrigerant discharged from the compression mechanism, and the expansion mechanism. In the refrigeration cycle apparatus including an evaporator that heats the refrigerant that has flowed out of the refrigerant, the design volume ratio of the compression mechanism and the expansion mechanism is set so that the ambient temperature of the evaporator is the lowest and the water temperature flowing into the radiator Characterized by being substantially the same as the ratio of the outlet refrigerant density of each of the radiator and the evaporator in the operating state of the refrigeration cycle apparatus in which the temperature of the hot water flowing out from the radiator is highest and the temperature of the hot water flowing out from the radiator is highest. To do.
A refrigeration cycle apparatus according to a seventh aspect of the present invention is a refrigeration cycle apparatus according to the present invention, wherein a compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, a radiator that cools the refrigerant discharged from the compression mechanism, and the expansion mechanism In the refrigeration cycle apparatus used as a hot water heater, the design volume ratio of the compression mechanism and the expansion mechanism is set to 10 or more. Features.
The refrigeration cycle apparatus of the present invention according to claim 8 connects the compression mechanism, the expansion mechanism, and the drive source to a single shaft, cools the refrigerant discharged from the compression mechanism, and the expansion mechanism. In the refrigeration cycle apparatus including the evaporator for heating the refrigerant flowing out from the refrigerant, the design volume ratio of the compression mechanism and the expansion mechanism is the lowest in the temperature of the air blown to the evaporator, and the radiator The ratio of the outlet refrigerant density of each of the radiator and the evaporator in the operating state of the refrigeration cycle apparatus in which the temperature of the air blown to the bottom is the lowest and the temperature of the air blown from the radiator is the highest. The feature is that they are substantially matched.
A refrigeration cycle apparatus according to a ninth aspect of the present invention is a refrigeration cycle apparatus according to the present invention, wherein a compression mechanism, an expansion mechanism, and a drive source are coupled to a single shaft, a radiator that cools the refrigerant discharged from the compression mechanism, and the expansion mechanism In the refrigeration cycle apparatus used as an air conditioner, the design volume ratio of the compression mechanism and the expansion mechanism is set to 8 or more. It is characterized by.
A control method for a refrigeration cycle apparatus according to a tenth aspect of the present invention includes a radiator that couples a compression mechanism, an expansion mechanism, and a drive source to a single shaft, and that cools the refrigerant discharged from the compression mechanism; An evaporator that heats the refrigerant that has flowed out of the expansion mechanism, a bypass channel that bypasses the expansion mechanism, a bypass valve that is provided on the bypass channel, and a pre-pressure reducing valve that depressurizes the refrigerant that flows into the expansion mechanism a refrigeration cycle apparatus comprising bets, the opening degree of said bypass valve said pre pressure reducing valve, by changing the basis of the discharge temperature or superheat of the refrigeration cycle device, characterized by adjusting the high side pressure And
A control method for a refrigeration cycle apparatus according to an eleventh aspect of the present invention includes a radiator that couples a compression mechanism, an expansion mechanism, and a drive source to a single shaft, and that cools the refrigerant discharged from the compression mechanism; In the refrigeration cycle apparatus including an evaporator that heats the refrigerant that has flowed out of the expansion mechanism, a bypass passage that bypasses the expansion mechanism, and a bypass valve that is provided on the bypass passage, the opening degree of the bypass valve And the rotation speed of the drive source are adjusted based on the discharge temperature or the degree of superheat of the refrigeration cycle apparatus, thereby adjusting the high-pressure side pressure .
A control method for a refrigeration cycle apparatus according to a twelfth aspect of the present invention includes a radiator that couples a compression mechanism, an expansion mechanism, and a drive source to a single shaft, and that cools the refrigerant discharged from the compression mechanism; A refrigeration cycle comprising an evaporator that heats the refrigerant flowing out of the expansion mechanism, a bypass passage that bypasses the expansion mechanism, a bypass valve provided on the bypass passage, and a fan that blows air to the evaporator In the apparatus, the high-pressure side pressure is adjusted by changing the opening degree of the bypass valve and the rotational speed of the fan based on a discharge temperature or a superheat degree of the refrigeration cycle apparatus .
According to a thirteenth aspect of the present invention, the refrigeration cycle apparatus of the present invention connects the auxiliary compression mechanism and the expansion mechanism to a single shaft, and further compresses the refrigerant discharged from the compression mechanism and the compression mechanism that compresses the refrigerant. In a refrigeration cycle apparatus comprising an auxiliary compression mechanism, a radiator that cools the refrigerant discharged from the auxiliary compression mechanism, and an evaporator that heats the refrigerant flowing out of the expansion mechanism, a bypass flow that bypasses the expansion mechanism A bypass valve provided on the bypass flow path, and an operating device that controls the operation of the bypass valve, and the operating device changes the opening of the bypass valve, thereby increasing the high-pressure side pressure. It is characterized by adjusting .
A fourteenth aspect of the present invention is the refrigeration cycle apparatus according to the thirteenth aspect of the present invention, further comprising a pre-reducing valve for depressurizing the refrigerant flowing into the expansion mechanism.
Is 15. refrigeration cycle apparatus of the present invention described, in the refrigeration cycle apparatus of the present invention according to claim 14, wherein the operating device is, the opening degree of said bypass valve said pre reducing valve, the refrigeration cycle apparatus and wherein the benzalkonium be changed based on the discharge temperature or superheat.
According to a sixteenth aspect of the present invention, in the refrigeration cycle apparatus according to the thirteenth aspect of the present invention, a design volume ratio of the auxiliary compression mechanism and the expansion mechanism is set so that the radiator and the compression are in an operating state of the refrigeration cycle apparatus. It is characterized in that it substantially matches the largest value among the ratios of the outlet refrigerant densities of the mechanisms.
According to a seventeenth aspect of the present invention, in the refrigeration cycle apparatus according to the thirteenth aspect of the present invention, the design volume ratio of the auxiliary compression mechanism and the expansion mechanism is the refrigeration in which the refrigerant density at the outlet of the radiator is the largest. It is characterized in that it substantially matches the ratio of the outlet refrigerant density of each of the radiator and the compression mechanism in the operating state of the cycle device.
The present invention according to claim 18 is the refrigeration cycle apparatus according to claim 13, wherein the design volume ratio of the auxiliary compression mechanism and the expansion mechanism is the lowest in ambient temperature of the evaporator, and the The temperature of the water flowing into the radiator is the lowest, and the temperature of the hot water flowing out of the radiator is the highest, and the ratio of the outlet refrigerant density of each of the radiator and the compression mechanism in the operating state of the refrigeration cycle apparatus is substantially the same. It is characterized by that.
According to a nineteenth aspect of the present invention, in the refrigeration cycle apparatus according to the thirteenth aspect of the present invention, carbon dioxide is used as a refrigerant, and the refrigeration cycle apparatus is used as a water heater. The design volume ratio of the expansion mechanism is 4 or more.

  The refrigeration cycle apparatus of the present invention and the control method thereof can be used within a wide operating range even in a refrigeration cycle apparatus using an expander that is difficult to adjust to the best high-pressure side pressure due to a constant density ratio. A refrigeration cycle apparatus capable of obtaining a high power recovery effect and efficient operation and a control method thereof.

The refrigeration cycle apparatus according to the first embodiment of the present invention includes a bypass flow path that bypasses the expansion mechanism, a bypass valve provided on the bypass flow path, a pre-reduction valve that depressurizes the refrigerant flowing into the expansion mechanism, and a bypass valve and a pre-reducing valve control the operations of the Gosuru operating device, the operating device is, the opening degree of the bypass valve and the pre-reducing valve, to change based on the discharge temperature or superheat of the refrigeration cycle apparatus Thus, the high pressure side pressure is adjusted . According to the present embodiment, even when the density ratio is smaller or larger than the design volume ratio, the opening pressure of the bypass valve and the pre-reducing valve can be adjusted to a desired high-pressure side pressure, and the operation efficiency over a wide range. And a refrigeration cycle apparatus that can be operated without lowering the capacity.
Refrigeration cycle apparatus according to a second embodiment of the present invention, control a bypass flow path for bypassing the expansion mechanism, a bypass valve provided in the bypass flow path, and a rotational speed of operation and the driving source of the bypass valve control And adjusts the high-pressure side pressure by changing the opening of the bypass valve and the rotational speed of the drive source based on the discharge temperature or the degree of superheat of the refrigeration cycle device. is there. According to the present embodiment, by operating the opening degree of the bypass valve and the driving rotational speed of the drive source, it can be adjusted to a desired high pressure side pressure in the actual operation state, and the opening degree of the bypass valve is fully opened. Even in this case, by operating the drive rotation speed of the drive source, the pressure can be adjusted to a desired high pressure side pressure, so that the operation efficiency and capacity of the refrigeration cycle apparatus are not reduced over a wide range.
A refrigeration cycle apparatus according to a third embodiment of the present invention includes a bypass flow path that bypasses the expansion mechanism, a bypass valve provided on the bypass flow path, a fan that blows air to the evaporator, and rotation of the bypass valve and the fan. and a and a control Gosuru manipulator numbers, operation device has a rotation speed of the opening degree of the bypass valve and the fan, by changing the basis of the discharge temperature or superheat of the refrigeration cycle apparatus, a high-pressure side pressure To be adjusted . According to the present embodiment, by operating the opening degree of the bypass valve and the rotational speed of the fan, it can be adjusted to a desired high pressure side pressure in the actual operation state, and even when the opening degree of the bypass valve is fully opened Since the rotation speed of the fan can be adjusted to a desired high-pressure side pressure, the operating efficiency and capacity of the refrigeration cycle apparatus are not reduced over a wide range.
In the refrigeration cycle apparatus according to the fourth embodiment of the present invention, the design volume ratio of the compression mechanism and the expansion mechanism is the largest among the ratios of the outlet refrigerant densities of the radiator and the evaporator in the operating state of the refrigeration cycle apparatus. Is approximately the same value as According to the present embodiment, a refrigeration cycle apparatus that reduces the seasonal difference in the COP improvement rate and maintains high operating efficiency at all times by adopting a design volume ratio that prevents pre-expansion as much as possible even when operating conditions are different. Is possible.
The refrigeration cycle apparatus according to the fifth embodiment of the present invention has a design volume ratio between the compression mechanism and the expansion mechanism, and a radiator and an evaporator in the operating state of the refrigeration cycle apparatus in which the refrigerant density at the outlet of the radiator is the largest. These are approximately the same as the ratio of the outlet refrigerant density. According to the present embodiment, a refrigeration cycle apparatus that reduces the seasonal difference in the COP improvement rate and maintains high operating efficiency at all times by adopting a design volume ratio that prevents pre-expansion as much as possible even when operating conditions are different. Is possible.
In the refrigeration cycle apparatus according to the sixth embodiment of the present invention, the design volume ratio of the compression mechanism and the expansion mechanism has the lowest ambient temperature of the evaporator, the lowest water temperature flowing into the radiator, and the heat dissipation. The ratio of the refrigerant density at the outlet of each of the radiator and the evaporator in the operating state of the refrigeration cycle apparatus in which the temperature of hot water flowing out from the vessel is the highest is substantially matched. According to the present embodiment, a refrigeration cycle apparatus that reduces the seasonal difference in the COP improvement rate and maintains high operating efficiency at all times by adopting a design volume ratio that prevents pre-expansion as much as possible even when operating conditions are different. Is possible.
In the refrigeration cycle apparatus according to the seventh embodiment of the present invention, the design volume ratio of the compression mechanism and the expansion mechanism is 10 or more. If the refrigeration cycle apparatus is a hot water heater, the present embodiment has a design volume ratio that prevents pre-expansion as much as possible even when operating conditions are different, and the seasonal difference in the COP improvement rate is small, so it is always high. A water heater that maintains operating efficiency is provided.
In the refrigeration cycle apparatus according to the eighth embodiment of the present invention, the design volume ratio of the compression mechanism and the expansion mechanism is set such that the temperature of air blown to the evaporator is the lowest and the temperature of air blown to the radiator. Is substantially the same as the ratio of the refrigerant density at the outlet of each of the radiator and the evaporator in the operating state of the refrigeration cycle apparatus in which the temperature of the air blown from the radiator is the highest. According to the present embodiment, a refrigeration cycle apparatus that reduces the seasonal difference in the COP improvement rate and maintains high operating efficiency at all times by adopting a design volume ratio that prevents pre-expansion as much as possible even when operating conditions are different. Is possible.
In the refrigeration cycle apparatus according to the ninth embodiment of the present invention, the design volume ratio of the compression mechanism and the expansion mechanism is 8 or more. If the refrigeration cycle apparatus is an air conditioner, the present embodiment has a design volume ratio that prevents pre-expansion as much as possible even if the operating conditions are different, and the seasonal difference in the COP improvement rate is always small. An air conditioner that maintains high operating efficiency is provided.
A control method for a refrigeration cycle apparatus according to a tenth embodiment of the present invention includes a radiator that couples a compression mechanism, an expansion mechanism, and a drive source to a single shaft, and that cools refrigerant discharged from the compression mechanism. An evaporator that heats the refrigerant that has flowed out of the expansion mechanism, a bypass flow path that bypasses the expansion mechanism, a bypass valve that is provided on the bypass flow path, and a pre-pressure reducing valve that depressurizes the refrigerant flowing into the expansion mechanism in the refrigeration cycle apparatus, the opening degree of the bypass valve and the pre-reducing valve, by changing the basis of the discharge temperature or superheat of the refrigeration cycle apparatus, and adjusts the high side pressure. According to the present embodiment, whether the density ratio is smaller or larger than the design volume ratio, the opening pressure of the bypass valve and the pre-reducing valve can be adjusted to a desired high pressure side pressure, and the refrigeration cycle can be achieved over a wide range. The device can be operated without reducing its operating efficiency and capacity.
A control method for a refrigeration cycle apparatus according to an eleventh embodiment of the present invention includes a radiator that couples a compression mechanism, an expansion mechanism, and a drive source to a single shaft and that cools refrigerant discharged from the compression mechanism. In the refrigeration cycle apparatus comprising an evaporator for heating the refrigerant flowing out of the expansion mechanism, a bypass flow path for bypassing the expansion mechanism, and a bypass valve provided on the bypass flow path, the opening degree of the bypass valve and the drive source Is adjusted based on the discharge temperature or superheat degree of the refrigeration cycle apparatus, thereby adjusting the high-pressure side pressure . According to the present embodiment, even when the density ratio is smaller or larger than the design volume ratio, it can be adjusted to a desired high-pressure side pressure by manipulating the opening degree of the bypass valve and the drive rotational speed of the drive source, and further the bypass Even if the opening of the valve is fully open, the operating efficiency and capacity of the refrigeration cycle system can be reduced over a wide range because the drive speed of the drive source can be adjusted to the desired high pressure side pressure. You can drive without.
A control method for a refrigeration cycle device according to a twelfth embodiment of the present invention includes a radiator that couples a compression mechanism, an expansion mechanism, and a drive source to a single shaft, and that cools refrigerant discharged from the compression mechanism. In a refrigeration cycle apparatus comprising an evaporator that heats the refrigerant that has flowed out of the expansion mechanism, a bypass passage that bypasses the expansion mechanism, a bypass valve provided on the bypass passage, and a fan that blows air to the evaporator, The high pressure side pressure is adjusted by changing the opening degree of the bypass valve and the rotational speed of the fan based on the discharge temperature or the superheat degree of the refrigeration cycle apparatus . According to the present embodiment, even when the density ratio is smaller or larger than the design volume ratio, it can be adjusted to a desired high-pressure side pressure by manipulating the opening degree of the bypass valve and the rotation speed of the fan, and the bypass valve Even when the opening degree is fully open, it can be adjusted to a desired high-pressure side pressure by manipulating the rotational speed of the fan, so that the refrigeration cycle apparatus can be operated over a wide range without reducing its operating efficiency and capacity.
A refrigeration cycle apparatus according to a thirteenth embodiment of the present invention connects an auxiliary compression mechanism and an expansion mechanism to a single shaft, and further compresses a refrigerant discharged from the compression mechanism and a compression mechanism that compresses the refrigerant. A bypass flow path that bypasses the expansion mechanism in a refrigeration cycle apparatus comprising: an auxiliary compression mechanism that performs cooling; a radiator that cools the refrigerant discharged from the auxiliary compression mechanism; and an evaporator that heats the refrigerant flowing out of the expansion mechanism. A bypass valve provided on the bypass flow path and an operating device that controls the operation of the bypass valve are provided, and the operating device adjusts the high-pressure side pressure by changing the opening of the bypass valve . According to the present embodiment, in the refrigeration cycle apparatus using an expander where it is difficult to maintain the optimum high-pressure side pressure due to a constant density ratio restriction, the density ratio change in the actual operating state Therefore, even if it differs from the design volume ratio assumed at the time of design, it can be operated without reducing the operating efficiency and capacity of the refrigeration cycle device by adjusting the pressure to the desired high-pressure side only by opening the bypass valve.
The fourteenth embodiment of the present invention is a refrigeration cycle apparatus according to the thirteenth embodiment, which includes a pre-decompression valve that depressurizes the refrigerant flowing into the expansion mechanism. According to the present embodiment, whether the density ratio is smaller or larger than the design volume ratio, the opening pressure of the bypass valve and the pre-reducing valve is adjusted to a desired high pressure side pressure, and the operating efficiency and capacity of the refrigeration cycle apparatus It can drive without lowering.
Fifteenth embodiment of the present invention is the refrigeration cycle apparatus according to the fourteenth embodiment, the operating device is, the opening degree of the bypass valve and the pre-reducing valve, the discharge temperature or superheat of the refrigeration cycle apparatus to change on the basis also of the is. According to the present embodiment, it is possible to operate without adjusting the operating efficiency and capacity of the refrigeration cycle apparatus by adjusting the pressure to a desired high pressure side by opening the bypass valve and the pre-reducing valve.
The sixteenth embodiment of the present invention is the refrigeration cycle apparatus according to the thirteenth embodiment, wherein the design volume ratio of the auxiliary compression mechanism and the expansion mechanism is set to the respective values of the radiator and the compression mechanism in the operating state of the refrigeration cycle apparatus. This is approximately matched with the largest value of the ratio of the outlet refrigerant density. According to the present embodiment, a refrigeration cycle apparatus that reduces the seasonal difference in the COP improvement rate and maintains high operating efficiency at all times by adopting a design volume ratio that prevents pre-expansion as much as possible even when operating conditions are different. Is possible.
According to a seventeenth embodiment of the present invention, in the refrigeration cycle apparatus according to the thirteenth embodiment, the design volume ratio of the auxiliary compression mechanism and the expansion mechanism is set so that the refrigerant density at the outlet of the radiator is the largest. This is approximately the same as the ratio of the outlet refrigerant density of the radiator and the compression mechanism in the operating state. According to the present embodiment, a refrigeration cycle apparatus that reduces the seasonal difference in the COP improvement rate and maintains high operating efficiency at all times by adopting a design volume ratio that prevents pre-expansion as much as possible even when operating conditions are different. Is possible.
According to an eighteenth embodiment of the present invention, in the refrigeration cycle apparatus according to the thirteenth embodiment, the design volume ratio of the auxiliary compression mechanism and the expansion mechanism is the lowest in the ambient temperature of the evaporator and flows into the radiator. The ratio of the refrigerant density at the outlet of each of the radiator and the compression mechanism in the operating state of the refrigeration cycle apparatus in which the temperature of the water to be discharged is the lowest and the temperature of the hot water flowing out from the radiator is the highest is substantially matched. According to the present embodiment, a refrigeration cycle apparatus that reduces the seasonal difference in the COP improvement rate and maintains high operating efficiency at all times by adopting a design volume ratio that prevents pre-expansion as much as possible even when operating conditions are different. Is possible.
A nineteenth embodiment of the present invention is a refrigeration cycle apparatus in which carbon dioxide is used as a refrigerant and used as a water heater in the refrigeration cycle apparatus according to the thirteenth embodiment. The auxiliary compression mechanism and the expansion mechanism The design volume ratio is set to 4 or more. If the refrigeration cycle apparatus is a water heater provided with an auxiliary compression mechanism, the present embodiment provides a design volume ratio that prevents pre-expansion as much as possible even with different operating conditions, and the seasonal difference in the COP improvement rate is small. Therefore, a refrigeration cycle apparatus that always maintains high operating efficiency is provided.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram showing a refrigeration cycle apparatus according to a first embodiment of the present invention. In addition, regarding the refrigeration cycle apparatus of the present embodiment, a hot water heater will be described as an example. That is, the present invention is not limited to the water heater of this embodiment, and may be an air conditioner or the like.
The refrigeration cycle apparatus of the present embodiment includes a refrigerant cycle circuit A including a compression mechanism 1, a radiator 2, an expansion mechanism 3, an evaporator 5 that exchanges heat with outside air blown by a fan 4, a feed water pump 6, and heat dissipation. And a hot water supply cycle circuit B including a hot water supply tank 7 and the like, and heat from the water supply pump 6 is heated by the refrigerant discharged from the compression mechanism 1 in the radiator 2 to form hot water. The refrigeration cycle apparatus (in the case of the present embodiment, a hot water heater) that is stored in
The compression mechanism 1 is driven by a drive source 8 such as a motor. Further, the compression mechanism 1 is connected to an expansion mechanism 3 (expander) that converts pressure energy into power by a single shaft 9, and reduces the input of the drive source 8 by the recovery power of the expansion mechanism 3. The refrigerant cycle circuit A is provided between the bypass flow path 10 that bypasses the expansion mechanism 3, the bypass valve 11 that adjusts the flow rate flowing through the bypass flow path 10, the radiator 2 and the expansion mechanism 3 inlet, And a pre-reducing valve 12 that depressurizes the refrigerant flowing into the expansion mechanism 3 in advance. Carbon dioxide (CO ₂ ) is enclosed as the refrigerant. Further, the discharge temperature detecting means 20 for detecting the outlet temperature of the compression mechanism 1 (the discharge temperature of the compression mechanism), and the opening degrees of the bypass valve 11 and the pre-reducing valve 12 are calculated based on the values detected by the discharge temperature detecting means 20, And a first operating device 21 to be operated.

Next, regarding the operation during operation of the refrigeration cycle apparatus configured as described above, the cylinder volume of the compression mechanism 1 is VC, the cylinder volume of the expansion mechanism 3 is VE, and the outlet refrigerant density of the evaporator 5 is DC (compression mechanism). 1 and the outlet refrigerant density of the radiator 2 will be described as DE (inflow refrigerant density of the expansion mechanism 3). First, a case will be described in which the density ratio (DE / DC) in an actual operation state is substantially equal to the design volume ratio (VC / VE) assumed at the time of design.
The compression mechanism 1 compresses the refrigerant to a pressure exceeding the critical pressure (high pressure side pressure). The compressed refrigerant enters a high-temperature and high-pressure state, and is cooled by releasing heat to water when flowing through the radiator 2. In other words, the water sent from the bottom of the hot water supply tank 7 to the water flow path of the radiator 2 by the water supply pump 6 is heated by the refrigerant flowing through the refrigerant flow path of the radiator 2. Thereafter, the refrigerant is decompressed by the expansion mechanism 3 and enters a gas-liquid two-phase state. The expansion mechanism 3 converts the pressure energy of the refrigerant into power, and the power is transmitted to the shaft 9. The input of the drive source 8 is reduced by the power transmitted to the shaft 9. The refrigerant depressurized by the expansion mechanism 3 flows into the evaporator 5 where the refrigerant is cooled by air to be in a gas-liquid two-phase or gas state. Thereafter, the refrigerant in the gas-liquid two-phase or gas state is sucked into the compression mechanism 1 again.

Next, a case where the density ratio (DE / DC) in the actual operation state is different from the design volume ratio (VC / VE) assumed at the time of design will be described. First, an operation when the density ratio (DE / DC) in the actual operation state is larger than the design volume ratio (VC / VE) assumed at the time of design will be described.
In this case, the refrigeration cycle should be balanced in a state where the high-pressure side pressure is reduced so that the refrigerant density (DE) at the outlet of the radiator 2 (inlet of the expansion mechanism 3) becomes small due to the restriction of the density ratio. And However, in a state where the high-pressure side pressure is lower than the desired pressure, the discharge temperature is lowered and the heating capacity of the refrigeration cycle apparatus is reduced, or the efficiency of the refrigeration cycle apparatus is reduced. Therefore, if the bypass valve 11 is not fully closed, the bypass valve 11 is operated in the closing direction, and the refrigerant that has flowed into the bypass flow path 10 is caused to flow into the expansion mechanism 3. Alternatively, if the bypass valve 11 is in a fully closed state, the pre-reducing valve 12 is operated in the closing direction to depressurize the refrigerant flowing into the expansion mechanism 3 and reduce the refrigerant density. By these operations, the high-pressure side pressure can be increased and adjusted to a desired pressure, so that an efficient operation can be performed.

Conversely, the operation when the density ratio (DE / DC) in the actual operation state is smaller than the design volume ratio (VC / VE) assumed at the time of design will be described.
In this case, the refrigeration cycle should be balanced in a state where the high-pressure side pressure is increased so that the refrigerant density (DE) at the outlet of the radiator 2 (inlet of the expansion mechanism 3) is increased due to the restriction of the constant density ratio. And However, in a state where the high-pressure side pressure is higher than the desired pressure, the operating efficiency of the refrigeration cycle apparatus is reduced. For this reason, if the pre-reducing valve 12 is not fully opened, the pre-reducing valve 12 is operated in the opening direction to increase the refrigerant density without depressurizing the refrigerant flowing into the expansion mechanism 3. Alternatively, if the pre-reducing valve 12 is in a fully open state, the bypass valve 11 is operated in the opening direction to cause a part of the refrigerant flowing into the expansion mechanism 3 to flow into the bypass flow path 10. By these operations, the high-pressure side pressure can be reduced and adjusted to a desired pressure, so that efficient operation can be performed.

  As described above, in the refrigeration cycle apparatus according to the first embodiment, in the refrigeration cycle apparatus using an expander in which it is difficult to maintain an optimum high-pressure side pressure due to a restriction of a constant density ratio, Whether the density ratio (DE / DC) in the operating state is smaller or larger than the designed volume ratio (VC / VE) assumed at the time of design, it is desirable depending on the opening operation of the bypass valve 11 and the pre-reducing valve 12. Provided is a refrigeration cycle apparatus that is adjusted to a high-pressure side pressure and can be operated without lowering operation efficiency and capacity.

Next, as a specific operation method of the bypass valve 11 and the pre-reducing valve 12, the control performed by the first controller 21 will be described based on the flowchart shown in FIG.
In the control of the present embodiment, the discharge temperature that can be measured relatively inexpensively regardless of the high pressure side pressure that requires a high-cost sensor to measure by utilizing the correlation between the high pressure side pressure and the discharge temperature. Thus, the bypass valve 11 and the pre-reducing valve 12 are controlled.
That is, when the refrigeration cycle apparatus is in operation, the detected value (discharge temperature Td) (step 100) from the discharge temperature detecting means 20 is captured. The target discharge temperature (target Td) stored in advance in the ROM or the like is compared with the discharge temperature taken in step 100 (step 110).
When the discharge temperature is lower than the target discharge temperature, the high-pressure side pressure tends to be lower than the optimum pressure, so it is first determined whether or not the bypass valve 11 is fully closed (step 120). When the bypass valve 11 is fully closed, the pre-reducing valve 12 is operated in the closing direction (step 130), the refrigerant flowing into the expansion mechanism 3 is depressurized, the refrigerant density is lowered, the high pressure side pressure and the discharge temperature. To raise. If the bypass valve 11 is not fully closed, the bypass valve 11 is operated in the closing direction (step 140), the amount of refrigerant flowing into the bypass flow path 10 that bypasses the expansion mechanism 3 is reduced, and the high pressure side pressure and Increase the discharge temperature.
On the other hand, when the discharge temperature is higher than the target discharge temperature, the high-pressure side pressure tends to be higher than the optimum pressure. Therefore, first, it is determined whether or not the pre-reducing valve 12 is fully opened (step 150). . When the pre-reducing valve 12 is fully open, the bypass valve 11 is operated in the opening direction (step 160), the amount of refrigerant flowing into the bypass passage 10 bypassing the expansion mechanism 3 is increased, and the high pressure side pressure and discharge are increased. Reduce temperature. Further, when the pre-reducing valve 12 is not fully opened, the pre-reducing valve 12 is operated in the opening direction (step 170) so that the refrigerant flowing into the expansion mechanism 3 is not depressurized so that the refrigerant density is not lowered. As a result, the high-pressure side pressure and the discharge temperature are reduced.
After the above steps, the process returns to step 100, and thereafter repeats from step 100 to step 170, thereby performing control in which the bypass valve 11 and the pre-reducing valve 12 are linked as shown in FIG.

As described above, in the control method for the refrigeration cycle apparatus according to the first embodiment, the refrigeration cycle apparatus using the expander that is difficult to maintain the optimum high-pressure side pressure due to the restriction of the constant density ratio. In this case, whether the density ratio (DE / DC) in the actual operation state is smaller or larger than the design volume ratio (VC / VE) assumed at the time of design, the bypass valve 11 and the pre-reducing valve are based on the discharge temperature. By operating the opening of 12, the pressure can be adjusted to a desired high pressure side pressure, and the operation can be performed without lowering the operation efficiency and capacity of the refrigeration cycle apparatus.
Note that the determination that the bypass valve 11 and the pre-reducing valve 12 are fully open or fully closed may not be physically open or fully closed, considering the reliability of the valve, etc. Then, it may be determined that the maximum opening degree or the minimum opening degree close to the full opening or the full opening determined in advance is reached.
The refrigerant of the present embodiment is described as a carbon dioxide (CO _2), and other refrigerants, for example, the same effect can R410A, etc. is obtained.

A refrigeration cycle apparatus according to the second embodiment of the present invention will be described. The refrigeration cycle apparatus of the present embodiment has substantially the same configuration as the refrigeration cycle apparatus of the first embodiment, and the same functional parts are denoted by the same reference numerals and description thereof is omitted. FIG. 4 is a block diagram showing a refrigeration cycle apparatus in the second embodiment of the present invention. FIG. 5 is a flowchart showing a control method of the refrigeration cycle apparatus in the second embodiment of the present invention.
In the refrigeration cycle apparatus of the present embodiment, the difference from the refrigeration cycle apparatus of the first embodiment is that instead of the discharge temperature detecting means 20 and the first operating device 21 of the first embodiment, the inlet of the evaporator 5 is used. Evaporation temperature detection means 30 for detecting the temperature between the outlets (evaporation temperature of the evaporator), suction temperature detection means 31 for detecting the inlet temperature of the compression mechanism 1 (suction temperature of the compression mechanism), and evaporation temperature detection means 30 And a second operating device 32 that calculates the degree of superheat (difference between the intake temperature and the evaporation temperature) from the values detected by the intake temperature detecting means 31 and calculates and operates the opening degrees of the bypass valve 11 and the pre-reducing valve 12; It is in the composition provided with.

Next, the control performed by the second controller 32 will be described based on the flowchart shown in FIG. In the control of this embodiment, the evaporating temperature that can be measured relatively inexpensively regardless of the high-pressure side pressure that requires a high-cost sensor to measure using the correlation between the high-pressure side pressure and the degree of superheat. The bypass valve 11 and the pre-reducing valve 12 are controlled based on the degree of superheat calculated from the suction temperature.
That is, during operation of the refrigeration cycle apparatus, the detection value (evaporation temperature Te) (step 200) from the evaporation temperature detection means 30 is taken in, and the detection value (intake temperature Ts) from the suction temperature detection means 31 (step 210). ) Is captured. The superheat degree (SH), which is the difference between the suction temperature and the evaporation temperature, is calculated from the acquired detection values (step 220), and the target superheat degree (target SH) stored in advance in the ROM or the like and the superheat calculated in step 200 are calculated. The degree is compared (step 230).
If the degree of superheat is lower than the target degree of superheat, the high pressure side pressure tends to be lower than the optimum pressure, so it is first determined whether or not the bypass valve 11 is fully closed (step 240). When the bypass valve 11 is fully closed, the pre-reducing valve 12 is operated in the closing direction (step 250), the refrigerant flowing into the expansion mechanism 3 is decompressed, the refrigerant density is lowered, and the high-pressure side pressure and discharge temperature are reduced. To raise. If the bypass valve 11 is not fully closed, the bypass valve 11 is operated in the closing direction (step 260), the amount of refrigerant flowing into the bypass flow path 10 that bypasses the expansion mechanism 3 is reduced, the high pressure side pressure and Increase superheat.
On the other hand, when the degree of superheat is higher than the target degree of superheat, the high pressure side pressure tends to be higher than the optimum pressure, so it is first determined whether or not the pre-reducing valve 12 is fully open (step 270). . When the pre-reducing valve 12 is fully open, the bypass valve 11 is operated in the opening direction (step 280), the amount of refrigerant flowing into the bypass flow path 10 that bypasses the expansion mechanism 3 is increased, and the high pressure side pressure and overheating are increased. Reduce the degree.
When the pre-reducing valve 12 is not fully opened, the pre-reducing valve 12 is operated in the opening direction (step 290) so that the refrigerant flowing into the expansion mechanism 3 is not depressurized so that the refrigerant density is not lowered. As a result, the high-pressure side pressure and the discharge temperature are reduced.
After the above steps, the process returns to step 200, and thereafter, by repeating from step 200 to step 290, the control in which the bypass valve 11 and the pre-pressure reducing valve 12 are linked is performed.

As described above, in the refrigeration cycle apparatus of the second embodiment and the control method thereof, the refrigeration cycle using the expander that is difficult to maintain the optimum high-pressure side pressure due to the restriction of the constant density ratio. In the apparatus, whether the density ratio (DE / DC) in the actual operation state is smaller or larger than the design volume ratio (VC / VE) assumed at the time of design, the bypass valve 11 and the pre-depressurization are based on the degree of superheat. By operating the opening degree of the valve 12, the pressure can be adjusted to a desired high pressure side pressure, and the operation can be performed without reducing the operation efficiency and capacity of the refrigeration cycle apparatus.
Note that the determination that the bypass valve 11 and the pre-reducing valve 12 are fully open or fully closed may not be physically open or fully closed, considering the reliability of the valve, etc. Then, it may be determined that the maximum opening degree or the minimum opening degree close to the full opening or the full opening determined in advance is reached.
The refrigerant of the present embodiment is described as a carbon dioxide (CO _2), and other refrigerants, for example, the same effect can R410A, etc. is obtained.

A refrigeration cycle apparatus according to a third embodiment of the present invention will be described. The refrigeration cycle apparatus of the present embodiment has substantially the same configuration as the refrigeration cycle apparatus of the first embodiment, and the same functional parts are denoted by the same reference numerals and description thereof is omitted. FIG. 6 is a block diagram showing a refrigeration cycle apparatus in the third embodiment of the present invention. FIG. 7 is a flowchart showing a control method of the refrigeration cycle apparatus in the third embodiment of the present invention.
In the refrigeration cycle apparatus of the present embodiment, the difference from the refrigeration cycle apparatus of the first embodiment is that the pre-reducing valve 12 of the first embodiment is not provided, and a bypass valve is based on the value detected by the discharge temperature detecting means 20. 11 and a third operating device 40 for operating the rotational speed of the drive source 8 that drives the compression mechanism 1.

Next, the control performed by the third controller 40 will be described based on the flowchart shown in FIG. In the control of the present embodiment, the control is performed based on the discharge temperature, as in the first embodiment.
That is, when the refrigeration cycle apparatus is in operation, the detected value (discharge temperature) (step 300) from the discharge temperature detecting means 20 is taken in. The target discharge temperature stored in advance in the ROM or the like is compared with the discharge temperature taken in step 300 (step 310).
When the discharge temperature is lower than the target discharge temperature, the high-pressure side pressure tends to be lower than the optimum pressure, so it is first determined whether or not the bypass valve 11 is fully closed (step 320). If the bypass valve 11 is fully closed, the drive rotational speed of the drive source 8 is increased (step 330). When the driving rotational speed increases, the circulation amount of the refrigerant discharged from the compression mechanism 1 increases and the heat exchange efficiency in the radiator 2 and the evaporator 5 decreases, so that the outlet temperature of the radiator 2 rises, and the expansion mechanism 3, the density of the refrigerant flowing into 3 decreases, the outlet temperature of the evaporator 5 decreases, and the density of refrigerant sucked into the compression mechanism 1 increases, so the density ratio (DE / DC) decreases. For this reason, the same effect as operating the pre-reducing valve 12 in the closing direction can be obtained, and the high-pressure side pressure and the discharge temperature can be increased.
If the bypass valve 11 is not fully closed, it is determined whether or not the drive rotational speed is smaller than a predetermined reference value (step 340). If the drive rotational speed is smaller than the reference value, it is considered that the drive rotational speed is reduced in step 380 described later. Therefore, the drive rotational speed is increased within the range up to the reference value (step 350), and the density ratio ( By reducing (DE / DC), the high-pressure side pressure and the discharge temperature are increased. When the drive rotational speed is the reference value, the bypass valve 11 is operated in the closing direction (step 360), the amount of refrigerant flowing into the bypass flow path 10 that bypasses the expansion mechanism 3 is reduced, and the high pressure side pressure is reduced. And increase the discharge temperature.

On the other hand, when the discharge temperature is higher than the target discharge temperature, the high-pressure side pressure tends to be higher than the optimum pressure, so it is first determined whether or not the bypass valve 11 is fully open (step 370). If the bypass valve 11 is fully open, the drive rotational speed of the drive source 8 is reduced (step 380). When the driving rotational speed is reduced, the circulation amount of the refrigerant discharged from the compression mechanism 1 is reduced, and the heat exchange efficiency in the radiator 2 and the evaporator 5 is improved. Therefore, the outlet temperature of the radiator 2 is lowered, and the expansion mechanism 3, the density of the refrigerant flowing into 3 increases, the outlet temperature of the evaporator 5 increases, and the density of refrigerant sucked into the compression mechanism 1 decreases, so that the density ratio (DE / DC) increases. For this reason, the same effect as operating the bypass valve 11 in the opening direction can be obtained, and the high-pressure side pressure and the discharge temperature can be reduced.
If the bypass valve 11 is not fully open, it is determined whether or not the drive rotational speed is greater than a predetermined reference value (step 390). If the drive rotational speed is greater than the reference value, it is considered that the drive rotational speed has been increased in step 330. Therefore, the drive rotational speed is decreased within the range up to the reference value (step 400), and the density ratio (DE / By increasing DC), the high-pressure side pressure and the discharge temperature are reduced. When the drive rotational speed is the reference value, the bypass valve 11 is operated in the opening direction (step 410), the amount of refrigerant flowing into the bypass flow path 10 that bypasses the expansion mechanism 3 is increased, and the high pressure side pressure is increased. And lowering the discharge temperature.
After the above steps, the process returns to step 300 and thereafter repeats from step 300 to step 410, thereby performing control in which the opening degree of the bypass valve 11 and the drive rotational speed of the drive source 8 are linked as shown in FIG. Do.

As described above, in the refrigeration cycle apparatus and control method thereof according to the third embodiment, a refrigeration cycle using an expander that is difficult to maintain an optimum high-pressure side pressure due to a restriction of a constant density ratio. In the apparatus, whether the density ratio (DE / DC) in the actual operation state is smaller or larger than the design volume ratio (VC / VE) assumed at the time of design, the opening degree of the bypass valve 11 based on the discharge temperature. By manipulating the driving rotational speed of the driving source 8, it can be adjusted to a desired high pressure side pressure.
Furthermore, even when the opening degree of the bypass valve 11 is fully opened as shown in FIG. 8, it can be adjusted to a desired high-pressure side pressure by operating the drive rotational speed of the drive source 8. It can be operated without lowering operating efficiency and capacity.
In this embodiment, the control is performed based on the discharge temperature as in the first embodiment. However, the control may be performed based on the degree of superheat as in the second embodiment. Further, the opening operation of the pre-reducing valve 12 of the first and second embodiments may be combined with the driving rotational speed operation of the driving source 8 of the present embodiment. Further, the determination that the bypass valve 11 is fully open or fully closed may not be physically open or fully closed, and is determined in advance in consideration of the reliability of the valve. You may determine by having become the full opening or the maximum opening degree close | similar to full closing, or the minimum opening degree. The refrigerant of the present embodiment is described as a carbon dioxide (CO _2), and other refrigerants, for example, the same effect can R410A, etc. is obtained.

A refrigeration cycle apparatus according to a fourth embodiment of the present invention will be described. The refrigeration cycle apparatus of the present embodiment has substantially the same configuration as the refrigeration cycle apparatus of the first embodiment, and the same functional parts are denoted by the same reference numerals and description thereof is omitted. FIG. 9 is a block diagram showing a refrigeration cycle apparatus in the fourth embodiment of the present invention. FIG. 10 is a flowchart showing a control method of the refrigeration cycle apparatus in the fourth embodiment of the present invention.
In the refrigeration cycle apparatus of the present embodiment, the difference from the refrigeration cycle apparatus of the first embodiment is that the pre-pressure reducing valve 12 of the first embodiment is not provided, and a bypass valve is based on the value detected by the discharge temperature detecting means 20. 11 and a fourth operating device 50 for operating the rotational speed of a drive source (not shown) for driving the fan 4.

Next, the control performed by the fourth controller 50 will be described based on the flowchart shown in FIG. In the control of the present embodiment, the control is performed based on the discharge temperature, as in the first embodiment.
That is, when the refrigeration cycle apparatus is in operation, the detected value (discharge temperature) (step 400) from the discharge temperature detecting means 20 is captured. The target discharge temperature stored in advance in the ROM or the like is compared with the discharge temperature taken in step 400 (step 410).
When the discharge temperature is lower than the target discharge temperature, the high-pressure side pressure tends to be lower than the optimum pressure, so it is first determined whether or not the bypass valve 11 is fully closed (step 420). If the bypass valve 11 is fully closed, the rotational speed of the fan 4 is increased (step 430). When the fan rotation speed increases, the evaporation pressure (pressure from the evaporator 5 inlet to the compression mechanism 1 inlet) increases, so that the refrigerant density at the outlet of the evaporator 5 increases, and the density ratio (DE / DC) decreases. For this reason, the same effect as operating the pre-reducing valve 12 in the closing direction can be obtained, and the high-pressure side pressure and the discharge temperature can be increased.
If the bypass valve 11 is not fully closed, it is determined whether or not the fan speed is smaller than a predetermined reference value (step 440). If the fan rotation speed is smaller than the reference value, it is considered that the fan rotation speed has been decreased in step 480 described later. Therefore, the fan rotation speed is increased within the range up to the reference value (step 450), and the density ratio ( By reducing (DE / DC), the high-pressure side pressure and the discharge temperature are increased. When the fan rotational speed is the reference value, the bypass valve 11 is operated in the closing direction (460), the amount of refrigerant flowing into the bypass passage 10 bypassing the expansion mechanism 3 is reduced, and the high pressure side pressure and Increase the discharge temperature.

On the other hand, when the discharge temperature is higher than the target discharge temperature, the high-pressure side pressure tends to be higher than the optimum pressure, so it is first determined whether or not the bypass valve 11 is fully open (step 470). If the bypass valve 11 is fully open, the drive rotational speed of the fan 4 is reduced (step 480). When the fan drive rotation speed decreases, the evaporation pressure decreases, and the refrigerant density at the outlet of the evaporator 5 decreases, so the density ratio (DE / DC) increases. For this reason, the same effect as operating the bypass valve 11 in the opening direction can be obtained, and the high-pressure side pressure and the discharge temperature can be reduced.
If the bypass valve 11 is not fully open, it is determined whether or not the fan rotation speed is greater than a predetermined reference value (step 490). If the fan rotational speed is larger than the reference value, it is considered that the fan rotational speed is increased in step 430. Therefore, the fan rotational speed is decreased within the range up to the reference value (step 500), and the density ratio (DE / By increasing the DC), the high-pressure side pressure and the discharge temperature are reduced. When the fan rotation speed is the reference value, the bypass valve 11 is operated in the opening direction (step 510), the amount of refrigerant flowing into the bypass flow path 10 that bypasses the expansion mechanism 3 is increased, and the high pressure side pressure is increased. And lowering the discharge temperature.
After the above steps, the process returns to step 400, and thereafter repeats from step 400 to step 510 to perform control in which the opening degree of the bypass valve 11 and the rotational speed of the fan 4 are linked as shown in FIG.

As described above, in the refrigeration cycle apparatus of the fourth embodiment and the control method thereof, the refrigeration cycle using the expander that is difficult to maintain the optimum high-pressure side pressure due to the restriction of the constant density ratio. In the apparatus, whether the density ratio (DE / DC) in the actual operation state is smaller or larger than the design volume ratio (VC / VE) assumed at the time of design, the opening degree of the bypass valve 11 is determined based on the degree of superheat. By manipulating the rotational speed of the fan 4, it can be adjusted to a desired high pressure side pressure.
Furthermore, even when the opening degree of the bypass valve 11 is fully opened as shown in FIG. 11, the operating efficiency of the refrigeration cycle apparatus can be adjusted by adjusting the rotational speed of the fan 4 to a desirable high pressure side pressure. And you can drive without reducing your ability.
In this embodiment, the control is performed based on the discharge temperature as in the first embodiment. However, the control may be performed based on the degree of superheat as in the second embodiment. Further, the opening operation of the pre-reducing valve 12 of the first and second embodiments, the driving rotation speed operation of the compression mechanism 11 of the third embodiment, and the rotation speed operation of the fan 4 of the present embodiment are implemented in combination. May be. Further, the determination that the bypass valve 11 is fully open or fully closed may not be physically open or fully closed, and is determined in advance in consideration of the reliability of the valve. You may determine by having become the full opening or the maximum opening degree close | similar to full closing, or the minimum opening degree. The refrigerant of the present embodiment is described as a carbon dioxide (CO _2), and other refrigerants, for example, the same effect can R410A, etc. is obtained.

A refrigeration cycle apparatus according to a fifth embodiment of the present invention will be described. Note that the configuration of the refrigeration cycle apparatus of the present embodiment and the control method thereof are the same as those of the first embodiment, and thus description of the same configuration, operation, and the like is omitted.
The characteristic configuration of the refrigeration cycle apparatus of the present embodiment is that the cylinder volume of the compression mechanism 1 is VC, the cylinder volume of the expansion mechanism 3 is VE, the outlet refrigerant density of the evaporator 5 is DC, and the outlet refrigerant density of the radiator 2 is In the case of DE, the design volume ratio (VC / VE) is almost equal to the value of the density ratio (DE / DC) under the condition that the density ratio (DE / DC) in the actual operation state is the largest. Designed to. Furthermore, specifically, it is the point which is designed so that it may substantially correspond to the value of the density ratio (DE / DC) under the condition that the outlet refrigerant density (DE) of the radiator 2 is maximized.
In the refrigeration cycle apparatus used as a water heater, the design volume ratio (VC / VE) has the lowest ambient temperature (outside air temperature) of the evaporator 5 within the range of use of the water heater, and a radiator. 2 so that the water temperature (incoming water temperature) flowing into 2 is the lowest, and the density ratio (DE / DC) when operating under the condition where the hot water temperature (outlet temperature) flowing out of the radiator 2 is the highest is almost the same. Characterized by the designed configuration.
Furthermore, specifically, the refrigeration cycle apparatus used as a hot water heater is characterized in that the design volume ratio (VC / VE) is designed to be a value of 10 or more.

  By the way, in the refrigeration cycle apparatus of the present embodiment, as described in the first embodiment, the density ratio (DE / DC) in the actual operation state is greater than the design volume ratio (VC / VE) determined at the time of design. If it is smaller, the pre-reducing valve 12 is operated in the opening direction by operating the bypass valve 11 in the opening direction or when the density ratio (DE / DC) is larger than the design volume ratio (VC / VE). By doing so, the density ratio (DE / DC) can be matched with the design volume ratio (VC / VE) and adjusted to a desired high pressure side pressure. However, if the amount of refrigerant flowing through the bypass passage 10 increases or the pressure difference that is pre-expanded by the pre-reducing valve 12 increases, the power that can be recovered decreases, so that the operating efficiency (COP) is improved. The rate will also decline. Therefore, it is important how to design the design volume ratio as an optimal value.

Then, the optimal design volume ratio when using the refrigerating cycle apparatus of a present Example as a hot water heater is demonstrated in detail using FIG. 12 and FIG.
FIG. 12 is a correlation diagram between the density ratio and the COP ratio in the fifth embodiment of the present invention, and FIG. 13 is a correlation diagram between the density ratio and the refrigerant density in the fifth embodiment of the present invention.
In FIG. 12, the outdoor air temperature is assumed to be summer, intermediate, winter, and low temperature in descending order. The incoming water temperature is assumed to be the lowest temperature corresponding to each outdoor air temperature condition, and the tapping temperature is assumed to be a standard temperature corresponding to each outdoor air temperature condition. The COP ratio was set to 100 for the refrigeration cycle apparatus that does not use the expander in each outside air temperature condition. In the following, description will be made taking summer conditions as an example.
Under summer conditions, the density ratio (DE / DC) in actual operating conditions is about 7. In the case of a refrigeration cycle apparatus designed with a design volume ratio (VC / VE) greater than this value, it is necessary to bypass the refrigerant to the bypass passage 10 in summer conditions. Conversely, in the case of a refrigeration cycle apparatus designed with a design volume ratio (VC / VE) smaller than this value, it is necessary to expand the pre-reducing valve 12 in advance in summer conditions. However, in both cases of bypass and pre-expansion, the COP ratio is reduced compared to when designed optimally under summer conditions, that is, when the design volume ratio (VC / VE) is designed to be about 7. It can be seen that when pre-expanded, the COP ratio drastically decreases.

  On the other hand, under winter conditions and low temperature conditions, the density ratio (DE / DC) in the actual operation state is about 10 and about 12, respectively. In the case of a refrigeration cycle apparatus designed with a design volume ratio (VC / VE) larger than these values, it is necessary to bypass the refrigerant to the bypass passage 10 under winter conditions and low temperature conditions. Conversely, in the case of a refrigeration cycle apparatus designed with a design volume ratio (VC / VE) smaller than these values, it is necessary to expand the pre-reducing valve 12 in advance in winter conditions and low temperature conditions. However, in both cases of bypass and pre-expansion, when designed optimally under winter conditions and low temperature conditions, that is, when designed volume ratio (VC / VE) is designed to be about 10 or about 12. It can be seen that the COP ratio is lower than that, particularly when the pre-expansion is performed.

That is, the optimum design volume ratio varies depending on the operating conditions that vary depending on the season, etc., but in the refrigeration cycle apparatus in which the compression mechanism 1 and the expansion mechanism 3 are directly connected by one shaft 9, the design volume ratio (VC / VE) Must be set to one value at the time of design. Therefore, for example, when the design volume ratio (VC / VE) is designed to be about 7 so as to be optimal under the summer conditions, the COP ratio is about 112 under the summer conditions, but the COP ratio under other seasonal conditions. Becomes approximately 101 to 103.
On the other hand, when the design volume ratio (VC / VE) is designed to be about 12 so as to be optimal under the low temperature condition, the COP ratio under the low temperature condition is about 110, and 107 under other seasonal conditions. ~ 108. Alternatively, when the design volume ratio (VC / VE) is designed to be optimal in winter conditions, the COP ratio in the low temperature period with a relatively short period is about 103, but in winter conditions, 110, and about 108 under other seasonal conditions.
In this way, if the design volume ratio (VC / VE) is designed to be optimal under winter conditions and low temperature conditions, the seasonal difference in the COP improvement rate can be reduced, and the operating conditions such as seasons are different. However, it is possible to always maintain high operating efficiency.

  That is, in the refrigeration cycle apparatus of the fifth embodiment, as is apparent from FIG. 12, it is possible even if the operating conditions are different, focusing on the fact that the improvement rate of COP is smaller when pre-expanding than when bypassing. In order to prevent pre-expansion as much as possible, the density at the design volume ratio (VC / VE) is the condition under which the density ratio (DE / DC) in the actual operation state is maximized (low-temperature condition in the case of FIG. 12). The refrigeration cycle operation that always maintains a high operation efficiency is possible by designing so as to substantially match the value of the ratio (DE / DC).

Furthermore, from the correlation between the outlet refrigerant density (DC) of the evaporator 5 shown in FIG. 13 or the outlet refrigerant density (DE) of the radiator 2 and the density ratio, the density ratio (DE / DC) is determined by the evaporator 5. From the change of the outlet refrigerant density (DC) of the radiator 2, it is more influenced by the change of the outlet refrigerant density (DE) of the radiator 2, and is further in a proportional relationship with the outlet refrigerant density (DE) of the radiator 2. .
Accordingly, the design volume ratio (VC / VE) of the refrigeration cycle apparatus of the present embodiment is set to the condition that the density ratio (DE / DC) in the actual operation state is the largest, that is, the outlet refrigerant density (DE) of the radiator 2. ) Is designed to substantially match the value of the density ratio (DE / DC) under the largest conditions, it is possible to operate the refrigeration cycle apparatus that always maintains high operating efficiency.

Further, as already described with reference to FIG. 12, in the refrigeration cycle apparatus used as a hot water heater, the ambient temperature (outside air temperature) of the evaporator 5 is the lowest within the use range and flows into the radiator 2. The ratio of the density of the refrigeration cycle device in the actual operating state (DE /) is determined when the water temperature (incoming water temperature) to be operated is the lowest and the hot water temperature to be discharged from the radiator 2 is the highest. DC) corresponds to a case where operation is performed under the maximum conditions (low-temperature condition in the case of FIG. 12), so that the density ratio (DE / DC) and the design volume ratio (VC / VE) in this operation state are Are designed so that they substantially coincide with each other, it is possible to perform a refrigeration cycle operation that always maintains high operation efficiency.
The condition that the density ratio (DE / DC) in the actual operating state of the refrigeration cycle apparatus is the largest is that if the refrigeration cycle apparatus is a water heater, the ambient temperature of the evaporator 5 is the lowest, and the radiator This corresponds to a condition in which the temperature of water flowing into 2 is the lowest and the temperature of hot water flowing out of the radiator 2 is the highest, but if applied to a general refrigeration cycle apparatus including an air conditioner described later, The temperature of the fluid that heats the refrigerant is the lowest, and the temperature of the inflowing fluid that flows into the radiator 2 in order to cool the refrigerant in the radiator 2 is the lowest. It is replaced that the temperature of the outflowing fluid is the highest.
Furthermore, in the refrigeration cycle apparatus used as a hot water heater, the design volume ratio (VC / VE) is designed to be a value of 10 or more (value corresponding to the winter condition and low temperature condition in the case of FIG. 12). Thus, a refrigeration cycle operation that always maintains high operating efficiency is possible.

The refrigeration cycle apparatus according to the sixth embodiment of the present invention will be described by taking an air conditioner as an example, not an example of the hot water heater of the first embodiment. FIG. 14 is a block diagram showing a refrigeration cycle apparatus in the sixth embodiment of the present invention. The refrigeration cycle apparatus of the present embodiment has substantially the same configuration as the refrigeration cycle apparatus of the first embodiment, and the same reference numerals are applied to the same functional parts. A description of the same configuration and its operation is omitted. Further, the control method of the refrigeration cycle apparatus is also the same as that in the first embodiment, and thus the description thereof is omitted.
The refrigeration cycle apparatus of the present embodiment includes an outdoor unit C and an indoor unit D. The outdoor unit C includes the compression mechanism 1, the first four-way valve 60, the outdoor heat exchanger 62 that exchanges heat with the air blown by the outdoor fan 61, the second four-way valve 63, the expansion mechanism 3, and the like. The indoor unit D includes an indoor heat exchanger 65 that exchanges heat with air blown by the indoor fan 64.
In the refrigeration cycle apparatus of the present embodiment, when the first four-way valve 60 and the second four-way valve 63 are switched to the solid line direction in the figure, the outdoor heat exchanger 62 acts as a radiator, and the indoor heat exchanger 65 is By acting as an evaporator, the room in which the indoor unit C is installed is cooled. When the first four-way valve 60 and the second four-way valve 63 are switched in the direction of the broken line in the figure, the indoor heat exchanger 65 acts as a radiator and the outdoor heat exchanger 62 acts as an evaporator. An air-conditioning operation for heating the room in which the machine C is installed is performed.

Furthermore, the characteristic configuration of the refrigeration cycle apparatus of the present embodiment is that the compression mechanism 1 has a cylinder volume VC, the expansion mechanism 3 has a cylinder volume VE, and either the outdoor heat exchanger 62 or the indoor heat exchanger 65 evaporates. The outlet refrigerant density of the heat exchanger when acting as a heat exchanger is DC (inflow refrigerant density of the compression mechanism 1), and the heat exchanger when either the outdoor heat exchanger 62 or the indoor heat exchanger 65 acts as a radiator When the outlet refrigerant density is DE (inflow refrigerant density of the expansion mechanism 3), the design volume ratio (VC / VE) is the condition under which the density ratio (DE / DC) in the actual operation state is the largest. The density ratio (DE / DC) is designed to be approximately the same. Furthermore, specifically, the density ratio (DE) under the condition that the outlet refrigerant density (DE) of the heat exchanger when either the outdoor heat exchanger 62 or the indoor heat exchanger 65 acts as a radiator is maximized. / DC) in that it is designed to substantially match the value.
Moreover, in the refrigeration cycle apparatus used as an air conditioner, the design volume ratio (VC / VE) has an outdoor heat exchanger 62 or an indoor heat exchanger 65 that acts as an evaporator within the use range of the air conditioner. The temperature of the air blown to any one of the heat exchangers is the lowest, and the temperature of the air blown to any one of the outdoor heat exchanger 62 or the indoor heat exchanger 65 acting as a radiator The structure is designed to be almost the same as the density ratio (DE / DC) when it is operated at the lowest temperature and the air temperature blown out from the heat exchanger acting as a radiator is the highest. And
Furthermore, specifically, in the refrigeration cycle apparatus used as an air conditioner, the design volume ratio (VC / VE) is characterized by a configuration designed to be a value of 8 or more.

Next, the optimal design volume ratio of the refrigeration cycle apparatus of the present embodiment used as an air conditioner will be described in detail with reference to FIGS. 15 and 16.
FIG. 15 is a correlation diagram between the density ratio and the COP ratio in the sixth embodiment of the present invention, and FIG. 16 is a correlation diagram between the density ratio and the refrigerant density in the sixth embodiment of the present invention.
In FIG. 15, the outdoor air temperature is assumed to be summer cooling, intermediate cooling, intermediate heating, and winter heating in descending order. The indoor temperature (the temperature of the air blown to the indoor heat exchanger 65) and the indoor blowing temperature (the temperature of the air blown from the indoor heat exchanger 65) are assumed to be standard temperatures corresponding to the respective outdoor air temperature conditions. . The COP ratio was set to 100 for the refrigeration cycle apparatus that does not use the expander in each outside air temperature condition. Hereinafter, description will be made taking summer cooling conditions as an example.
Under summer cooling conditions, the density ratio (DE / DC) in actual operating conditions is about 4. In the case of a refrigeration cycle apparatus designed with a design volume ratio (VC / VE) larger than this value, it is necessary to bypass the refrigerant to the bypass passage 10 under summer cooling conditions. Conversely, in the case of a refrigeration cycle apparatus designed with a design volume ratio (VC / VE) smaller than this value, it is necessary to expand the pre-reducing valve 12 in advance under summer cooling conditions. However, in both cases of bypass and pre-expansion, the COP ratio is lower than when designed optimally under summer cooling conditions, that is, compared with the case where the design volume ratio (VC / VE) is designed to be about 4, In particular, it can be seen that the COP ratio drastically decreases when pre-expanded.
On the other hand, in the intermediate heating condition and the winter heating condition, the density ratio (DE / DC) in the actual operation state is about 8 to 9, respectively. In the case of a refrigeration cycle apparatus designed with a design volume ratio (VC / VE) larger than these values, it is necessary to bypass the refrigerant to the bypass passage 10 under intermediate heating conditions and winter heating conditions. Conversely, in the case of a refrigeration cycle apparatus designed with a design volume ratio (VC / VE) smaller than these values, it is necessary to expand in advance with the pre-reducing valve 12 under intermediate heating conditions and winter heating conditions. However, in both cases of bypass and pre-expansion, when designed optimally under the respective intermediate heating conditions and winter heating conditions, that is, the design volume ratio (VC / VE) is designed to be about 8-9. It can be seen that the COP ratio decreases compared to the case, and particularly when the pre-expansion is performed, the COP ratio rapidly decreases greatly.

That is, the optimum design volume ratio varies depending on the operating conditions that vary depending on the season, etc., but in the refrigeration cycle apparatus in which the compression mechanism 1 and the expansion mechanism 3 are directly connected by one shaft 9, the design volume ratio (VC / VE) Must be set to one value at the time of design. For this reason, for example, when the design volume ratio (VC / VE) is designed to be about 4 so as to be optimal under the summer cooling conditions, the COP ratio is about 130 under the summer cooling conditions. Under winter heating conditions, the COP ratio is about 102-104.
On the other hand, when the design volume ratio (VC / VE) is designed to be about 8-9 so as to be optimal in the intermediate heating condition and the winter heating condition, the COP ratio in the intermediate heating condition and the winter heating condition. Is about 111, which is 113 to 114 even under summer cooling conditions and intermediate cooling conditions.
In this way, if the design volume ratio (VC / VE) is designed to be optimal under intermediate heating conditions and winter heating conditions, the seasonal difference in the COP improvement rate can be reduced, and the operating conditions such as seasons can be reduced. Even if they are different, it is possible to always maintain high operating efficiency.

  That is, in the refrigeration cycle apparatus of the sixth embodiment, as is apparent from FIG. 15, it is possible even if the operating conditions are different, focusing on the fact that the improvement rate of COP is smaller when pre-expanding than when bypassing. In order to prevent pre-expansion as much as possible, the design volume ratio (VC / VE) is the density under the condition (the winter heating condition in the case of FIG. 15) where the density ratio (DE / DC) in the actual operation state is the largest. The refrigeration cycle operation that always maintains a high operation efficiency is possible by designing so as to substantially match the value of the ratio (DE / DC).

Moreover, either the outdoor refrigerant | coolant density (DC) when either the outdoor heat exchanger 62 shown in FIG. 16 or the indoor heat exchanger 65 acts as an evaporator, or either the outdoor heat exchanger 62 or the indoor heat exchanger 65 is shown. From the correlation between the outlet refrigerant density (DE) when the refrigerant acts as a radiator and the density ratio (DE / DC), the density ratio (DE / DC) is determined from the change in the outlet refrigerant density (DC) of the evaporator. It can be seen that it is more influenced by the change in the outlet refrigerant density (DE) of the radiator 2 and that it is substantially proportional to the outlet refrigerant density (DE) of the radiator 2.
Therefore, in the refrigeration cycle apparatus of the present embodiment, the design volume ratio (VC / VE) is set to the condition that the density ratio (DE / DC) in the actual operating state is the largest, that is, the outlet refrigerant density ( The refrigeration cycle operation that always maintains high operation efficiency is possible by designing it so as to substantially match the value of the density ratio (DE / DC) under the condition where DE) is the largest.

Moreover, as already demonstrated in FIG. 15, in the refrigerating cycle apparatus used as an air conditioner, either the outdoor heat exchanger 62 or the indoor heat exchanger 65 which acts as an evaporator is within the use range. The temperature of the air blown to the heat exchanger is the lowest, and the temperature of the air blown to either the outdoor heat exchanger 62 or the indoor heat exchanger 65 acting as a radiator is the lowest, And when operated under conditions where the temperature of the air blown from the heat exchanger acting as a radiator is the highest, it is operated under conditions where the density ratio (DE / DC) in the actual operating state is maximized (Winter heating conditions in the case of FIG. 15), the density ratio (DE / DC) in this operation state and the design volume ratio (VC / VE) are always designed to be almost the same. High driving Refrigeration cycle operation of maintaining the rate is possible.
Further, in the refrigeration cycle apparatus used as an air conditioner, the design volume ratio (VC / VE) is set to a value of 8 or more (value corresponding to the winter heating condition and the intermediate heating condition in the case of FIG. 15). By designing the refrigeration cycle, it is possible to operate the refrigeration cycle while always maintaining high operating efficiency.

A refrigeration cycle apparatus according to a seventh embodiment of the present invention will be described. FIG. 17 is a block diagram showing a refrigeration cycle apparatus in the seventh embodiment of the present invention. The refrigeration cycle apparatus of the present embodiment has substantially the same configuration as the refrigeration cycle apparatus of the first embodiment, and the same functional parts are denoted by the same reference numerals and description thereof is omitted. Further, the control method of the refrigeration cycle apparatus is also the same as that in the first embodiment, and thus the description thereof is omitted. The refrigeration cycle apparatus of the present embodiment will be described by taking a hot water heater as an example.
The refrigeration cycle apparatus of the present embodiment includes a refrigerant cycle circuit A and a hot water supply cycle circuit B. The refrigerant cycle circuit A includes a driving source 71 such as a motor, a compression mechanism 72 driven by the driving source 71, an auxiliary compression mechanism 73 that further compresses the refrigerant discharged from the compression mechanism 72, the radiator 2, and an expansion mechanism 74. And an evaporator 5 for exchanging heat with the outside air blown by the fan 4. The hot water supply cycle circuit B includes a water supply pump 6, a radiator 2, a hot water supply tank 7, and the like, as in the configuration of the first embodiment. Further, the auxiliary compression mechanism 73 is connected to an expansion mechanism 74 that converts pressure energy into power and a shaft 75, and is driven by the recovery power of the expansion mechanism 74.

Next, regarding the operation during operation of the refrigeration cycle apparatus configured as described above, the cylinder volume of the auxiliary compression mechanism 73 is VCs, the cylinder volume of the expansion mechanism 74 is VE, and the outlet refrigerant density of the compression mechanism 72 is DCs (auxiliary). The description will be made assuming that the inflow refrigerant density of the compression mechanism 73) and the outlet refrigerant density of the radiator 2 are DE (inflow refrigerant density of the expansion mechanism 3). First, the case where the density ratio (DE / DCs) in the actual operation state is substantially equal to the design volume ratio (VCs / VE) assumed at the time of design will be described.
The compression mechanism 72 compresses the refrigerant to a pressure exceeding the critical pressure (intermediate pressure). The compressed refrigerant is further compressed to a high pressure side pressure by the auxiliary compression mechanism 73. And when the refrigerant | coolant used as the high temperature / high pressure state flows through the heat radiator 2, it radiates heat to water and is cooled. Thereafter, the refrigerant is decompressed by the expansion mechanism 74 to be in a gas-liquid two-phase state. The expansion mechanism 74 converts pressure energy of the refrigerant into power, and the power is transmitted to the shaft 75. The auxiliary compression mechanism 73 is driven by the power transmitted to the shaft 75. The refrigerant depressurized by the expansion mechanism 74 flows into the evaporator 5 where the refrigerant is cooled by air to be in a gas-liquid two-phase or gas state. Thereafter, the refrigerant in the gas-liquid two-phase or gas state is again sucked into the compression mechanism 72.

Next, the case where the density ratio (DE / DCs) in the actual operation state is different from the design volume ratio (VCs / VE) assumed at the time of design will be described. First, the operation when the density ratio (DE / DCs) in the actual operation state is larger than the design volume ratio (VCs / VE) assumed at the time of design will be described.
In this case, the refrigeration cycle should be balanced in a state where the high-pressure side pressure is reduced so that the refrigerant density (DE) at the outlet of the radiator 2 (inlet of the expansion mechanism 74) is reduced due to the restriction of the density ratio. And However, in a state where the high-pressure side pressure is lower than the desired pressure, the discharge temperature is lowered and the heating capacity of the refrigeration cycle apparatus is reduced, or the efficiency of the refrigeration cycle apparatus is reduced. For this reason, if the bypass valve 11 is not fully closed, the bypass valve 11 is operated in the closing direction, and the refrigerant that has flowed into the bypass flow path 10 is caused to flow into the expansion mechanism 74. Alternatively, if the bypass valve 11 is in the fully closed state, the pre-reducing valve 12 is operated in the closing direction to depressurize the refrigerant flowing into the expansion mechanism 74 and reduce the refrigerant density. By these operations, the high-pressure side pressure can be increased and adjusted to a desired pressure, so that an efficient operation can be performed.

Conversely, the operation when the density ratio (DE / DCs) in the actual operation state is smaller than the design volume ratio (VCs / VE) assumed at the time of design will be described.
In this case, the refrigeration cycle should be balanced in a state where the high-pressure side pressure is increased so that the refrigerant density (DE) at the outlet of the radiator 2 (inlet of the expansion mechanism 74) is increased due to the restriction of the constant density ratio. And However, in a state where the high-pressure side pressure is higher than the desired pressure, the operating efficiency of the refrigeration cycle apparatus is reduced. Therefore, if the pre-reducing valve 12 is not fully opened, the pre-reducing valve 12 is operated in the opening direction to increase the refrigerant density without reducing the pressure of the refrigerant flowing into the expansion mechanism 74. Alternatively, if the pre-pressure reducing valve 12 is in a fully open state, the bypass valve 11 is operated in the opening direction so that a part of the refrigerant flowing into the expansion mechanism 74 flows into the bypass flow path 10. By these operations, the high-pressure side pressure can be reduced and adjusted to a desired pressure, so that efficient operation can be performed.

As described above, in the refrigeration cycle apparatus according to the seventh embodiment, in the refrigeration cycle apparatus using an expander in which it is difficult to maintain the optimum high-pressure side pressure due to the restriction of a constant density ratio, Whether the density ratio (DE / DCs) in the operation state is smaller or larger than the design volume ratio (VCs / VE) assumed at the time of design, it is desirable depending on the opening operation of the bypass valve 11 and the pre-reducing valve 12. It is possible to operate without adjusting the operation efficiency and capacity of the refrigeration cycle device by adjusting to the high pressure side pressure.
The discharge temperature of the refrigeration cycle in the present embodiment is the outlet temperature of the auxiliary compression mechanism 73, and the superheat degree of the refrigeration cycle is the difference between the suction temperature of the compression mechanism 72 and the evaporation temperature of the evaporator 5.

A refrigeration cycle apparatus in the eighth embodiment of the present invention will be described. In addition, since the structure of the refrigerating-cycle apparatus and its control method of a present Example are the same as that of a 7th Example, description about the same structure, operation | movement, etc. is abbreviate | omitted.
The characteristic configuration of the refrigeration cycle apparatus of this embodiment is that the cylinder volume of the auxiliary compression mechanism 73 is VCs, the cylinder volume of the expansion mechanism 74 is VE, the outlet refrigerant density of the compression mechanism 72 is DCs, and the outlet refrigerant density of the radiator 2 is. When DE is DE, the design volume ratio (VCs / VE) is almost the same as the value of the density ratio (DE / DCs) under the condition that the density ratio (DE / DCs) in the actual operation state is the largest. Designed to be Furthermore, specifically, it is in the point designed so that it may correspond with the value of the density ratio (DE / DCs) in the conditions where the outlet refrigerant density (DE) of the heat radiator 2 becomes the largest.
In the refrigeration cycle apparatus used as a water heater, the design volume ratio (VCs / VE) has the lowest ambient temperature (outside air temperature) of the evaporator 5 within the range of use of the water heater, and a radiator. 2 so that it substantially matches the density ratio (DE / DCs) when the water temperature (incoming water temperature) flowing into 2 is the lowest and the hot water temperature (outlet temperature) flowing out of the radiator 2 is the highest. Characterized by the designed configuration.
Furthermore, specifically, a refrigeration cycle apparatus used as a hot water supply apparatus is characterized in that the design volume ratio (VCs / VE) is designed to be a value of 3.5 or more.

  By the way, in the refrigeration cycle apparatus of the present embodiment, as described in the first embodiment, the density ratio (DE / DCs) in the actual operation state is greater than the design volume ratio (VCs / VE) determined at the time of design. If it is smaller, the pre-reducing valve 12 is operated in the opening direction by operating the bypass valve 11 in the opening direction or when the density ratio (DE / DCs) is larger than the design volume ratio (VCs / VE). By doing so, the density ratio (DE / DCs) can be matched with the design volume ratio (VCs / VE) and adjusted to a desired high pressure side pressure. However, if the amount of refrigerant flowing through the bypass passage 10 increases or the pressure difference that is pre-expanded by the pre-reducing valve 12 increases, the power that can be recovered decreases, so that the operating efficiency (COP) is improved. The rate will also decline. Therefore, it is important how to design the design volume ratio as an optimal value.

Then, the optimal design volume ratio when using the refrigeration cycle apparatus of a present Example as a hot water heater is demonstrated in detail using FIG. 18 and FIG.
FIG. 18 is a correlation diagram between the density ratio and the COP ratio in the eighth embodiment of the present invention, and FIG. 19 is a correlation diagram between the density ratio and the refrigerant density in the eighth embodiment of the present invention.
In FIG. 18, the outdoor temperature is assumed to be summer, intermediate, winter, and low temperature in descending order of temperature. The incoming water temperature is assumed to be the lowest temperature corresponding to each outdoor air temperature condition, and the tapping temperature is assumed to be a standard temperature corresponding to each outdoor air temperature condition. The COP ratio was set to 100 for the refrigeration cycle apparatus that does not use the expander in each outside air temperature condition. In the following, description will be made taking summer conditions as an example.
Under summer conditions, the density ratio (DE / DCs) in actual operating conditions is about 4.1. In the case of a refrigeration cycle apparatus designed with a design volume ratio (VCs / VE) larger than this value, it is necessary to bypass the refrigerant to the bypass passage 10 in summer conditions. Conversely, in the case of a refrigeration cycle apparatus designed with a design volume ratio (VCs / VE) smaller than this value, it is necessary to expand the pre-reducing valve 12 in advance in summer conditions. However, in both cases of bypass and pre-expansion, the COP ratio is lower than when designed optimally under summer conditions, that is, when designed with a design volume ratio (VCs / VE) of about 4.1. In particular, it can be seen that the COP ratio drastically decreases when pre-expanded.

  On the other hand, under winter conditions and low temperature conditions, the density ratios (DE / DCs) in the actual operation state are about 4.3 and about 4.5, respectively. In the case of a refrigeration cycle apparatus designed with a design volume ratio (VCs / VE) larger than these values, it is necessary to bypass the refrigerant to the bypass passage 10 in winter conditions and low temperature conditions. Conversely, in the case of a refrigeration cycle apparatus designed with a design volume ratio (VCs / VE) smaller than these values, it is necessary to expand the pre-reducing valve 12 in advance in winter conditions or low temperature conditions. However, in both cases of bypass and pre-expansion, when designed optimally under winter conditions and low temperature conditions, that is, the design volume ratio (VCs / VE) is about 4.3 or about 4.5. It can be seen that the COP ratio decreases compared to the case where the COP ratio is designed, and in particular, the COP ratio rapidly decreases greatly when pre-expanded.

That is, the optimum design volume ratio varies depending on the operating conditions that vary depending on the season, etc., but in the refrigeration cycle apparatus in which the auxiliary compression mechanism 73 and the expansion mechanism 74 are directly connected by a single shaft 75, the design volume ratio (VCs / VE ) Must be set to one value at the time of design. For this reason, for example, when the design volume ratio (VCs / VE) is designed to be about 4.1 so as to be optimal under summer conditions, the COP ratio is about 112 under summer conditions, but under other seasonal conditions. The COP ratio is about 105.
On the other hand, when the design volume ratio (VCs / VE) is designed to be about 4.5 so as to be optimal under the low temperature condition, the COP ratio under the low temperature condition is about 110. But it becomes 110-111. Alternatively, the same applies when the design volume ratio (VCs / VE) is designed to be optimal under winter conditions.
In this way, if the design volume ratio (VCs / VE) is designed to be optimal under winter conditions and low temperature conditions, the seasonal difference in COP improvement rate can be reduced and the operating conditions such as seasons differ. However, it is possible to always maintain high operating efficiency.

  That is, in the refrigeration cycle apparatus of the eighth embodiment, as apparent from FIG. 18, it is possible even if the operating conditions are different, paying attention to the fact that the improvement rate of COP is smaller when pre-expanding than when bypassing. In order to prevent pre-expansion as much as possible, the design volume ratio (VCs / VE) is a density under the condition that the density ratio (DE / DCs) in the actual operation state is the largest (in the case of FIG. 18, the low temperature period condition). The refrigeration cycle operation that always maintains a high operation efficiency is possible by designing it so that it substantially coincides with the value of the ratio (DE / DCs).

Further, from the correlation between the outlet refrigerant density (DCs) of the compression mechanism 71 shown in FIG. 19 or the outlet refrigerant density (DE) of the radiator 2 and the density ratio (DE / DCs), the density ratio (DE / DCs). Is more influenced by the change in the outlet refrigerant density of the radiator 2 than the change in the outlet refrigerant density (DCs) of the compression mechanism 71, and is substantially proportional to the outlet refrigerant density (DE) of the radiator 2. I understand.
Therefore, the design volume ratio (VCs / VE) of the refrigeration cycle apparatus of the present embodiment is set to the condition that the density ratio (DE / DCs) in the actual operation state is the largest, that is, the outlet refrigerant density (DE) of the radiator 2. ) Is designed to substantially match the value of the density ratio (DE / DCs) under the largest conditions, it is possible to operate the refrigeration cycle apparatus that always maintains high operating efficiency.

Further, as already described with reference to FIG. 18, in the refrigeration cycle apparatus used as a hot water heater, the ambient temperature (outside air temperature) of the evaporator 5 is the lowest within the use range and flows into the radiator 2. The ratio of the density of the refrigeration cycle device in the actual operating state (DE /) is determined when the water temperature (incoming water temperature) to be operated is the lowest and the hot water temperature to be discharged from the radiator 2 is the highest. DCs) corresponds to the case where the operation is performed at the maximum condition (low temperature period condition in the case of FIG. 18), and therefore the density ratio (DE / DCs) in this operation state and the design volume ratio (VCs / VE) Are designed so that they substantially coincide with each other, it is possible to perform a refrigeration cycle operation that always maintains high operation efficiency.
Further, in the refrigeration cycle apparatus used as a water heater provided with the auxiliary compression mechanism 73, the design volume ratio (VCs / VE) is set to a value of 4 or more (summer condition, intermediate condition, winter condition in FIG. The refrigeration cycle operation that always maintains a high operation efficiency is possible by designing it to be a value that corresponds to almost all of the low temperature conditions.
Furthermore, according to the configuration of the present embodiment, as shown in FIG. 18, the change in the volume ratio when the operation conditions such as the season are different is smaller than in FIG. 12 of the fifth embodiment. It is possible to operate the refrigeration cycle apparatus that always maintains high operating efficiency.
In other words, in the refrigeration cycle apparatus including the auxiliary compression mechanism 73, since the change in the volume ratio in the actual operation state is small, the opening degree of only the bypass valve 11 is different from the design volume ratio set at the time of design. The operation can be adjusted to a desired high pressure side pressure, and a refrigeration cycle operation that always maintains a high operation efficiency is possible. That is, it is possible to use only the bypass valve 11 without the pre-reducing valve 12, and even in the case of only the bypass valve 11, it is desirable to set the design volume ratio set at the time of design to a larger value.

  The refrigeration cycle apparatus and its control method of the present invention are suitable for a hot water supply apparatus (hot water heater), a domestic air conditioner, a commercial air conditioner, a vehicle air conditioner (car air conditioner), and the like. In addition, it is possible to provide a refrigeration cycle apparatus capable of obtaining a high power recovery effect in a wide operation range and performing an efficient operation. In particular, the effect is large in a refrigeration cycle apparatus in which the high pressure side of the refrigeration cycle using carbon dioxide can be in a supercritical state.

The block diagram which shows the refrigerating-cycle apparatus in 1st Example of this invention. The flowchart which shows the control method of the refrigerating-cycle apparatus in 1st Example of this invention. The schematic diagram which shows the relationship of the control means in 1st Example of this invention The block diagram which shows the refrigerating-cycle apparatus in 2nd Example of this invention. The flowchart which shows the control method of the refrigerating-cycle apparatus in 2nd Example of this invention. The block diagram which shows the refrigerating-cycle apparatus in the 3rd Example of this invention. The flowchart which shows the control method of the refrigerating-cycle apparatus in the 3rd Example of this invention. The schematic diagram which shows the relationship of the control means in 3rd Example of this invention. The block diagram which shows the refrigerating-cycle apparatus in the 4th Example of this invention. The flowchart which shows the control method of the refrigerating-cycle apparatus in the 4th Example of this invention. The schematic diagram which shows the relationship of the control means in 4th Example of this invention Correlation diagram between density ratio and COP ratio in the fifth embodiment of the present invention Correlation diagram between density ratio and refrigerant density in the fifth embodiment of the present invention The block diagram which shows the refrigerating-cycle apparatus in the 6th Example of this invention. Correlation diagram between density ratio and COP ratio in the sixth embodiment of the present invention Correlation diagram between density ratio and refrigerant density in the sixth embodiment of the present invention The block diagram which shows the refrigerating-cycle apparatus in the 7th Example of this invention. Correlation diagram between density ratio and COP ratio in the eighth embodiment of the present invention Correlation diagram between density ratio and refrigerant density in the eighth embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,72 Compression mechanism 2 Radiator 3,74 Expansion mechanism 4 Fan 5 Evaporator 6 Water supply pump 7 Hot water supply tank 8,71 Drive source 9,75 Shaft 10 Bypass flow path 11 Bypass valve 12 Pre-reduction valve 20 Discharge temperature detection means 21 First operation unit 30 Evaporation temperature detection means 31 Suction temperature detection unit 32 Second operation unit 40 Third operation unit 50 Fourth operation unit 60 First four-way valve 61 Outdoor heat exchanger 62 Outdoor fan 63 Second four-way valve 64 Indoor heat Exchanger 65 Indoor fan 73 Auxiliary compression mechanism A Refrigerant cycle circuit B Hot water supply cycle circuit C Outdoor unit D Indoor unit

Claims (19)

A compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, and a radiator that cools the refrigerant discharged from the compression mechanism and an evaporator that heats the refrigerant flowing out of the expansion mechanism are provided. In the refrigeration cycle apparatus, a bypass flow path that bypasses the expansion mechanism, a bypass valve provided on the bypass flow path, a pre-reduction valve that depressurizes refrigerant flowing into the expansion mechanism, the bypass valve, and the pre-decompression pressure and a control Gosuru operating device the operation of the valve, the operating device is, the opening degree of said bypass valve said pre pressure reducing valve, by changing the basis of the discharge temperature or superheat of the refrigeration cycle apparatus A refrigeration cycle apparatus for adjusting a high-pressure side pressure . A compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, and a radiator that cools the refrigerant discharged from the compression mechanism and an evaporator that heats the refrigerant flowing out of the expansion mechanism are provided. in the refrigeration cycle apparatus includes a bypass flow path for bypassing said expansion mechanism, a bypass valve provided in the bypass flow path, and a control Gosuru operating device and a rotational speed of operation and the driving source of the bypass valve The operating device adjusts the high-pressure side pressure by changing the opening degree of the bypass valve and the rotational speed of the drive source based on the discharge temperature or the degree of superheat of the refrigeration cycle apparatus. Refrigeration cycle equipment. A compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, and a radiator that cools the refrigerant discharged from the compression mechanism and an evaporator that heats the refrigerant flowing out of the expansion mechanism are provided. in the refrigeration cycle device, a bypass passage bypassing the expansion mechanism, a bypass valve provided in the bypass flow path, and a fan for blowing air to the evaporator, Gosei the rotational speed of the fan and the bypass valve And adjusting the high-pressure side pressure by changing the opening degree of the bypass valve and the rotational speed of the fan based on the discharge temperature or the superheat degree of the refrigeration cycle apparatus. A refrigeration cycle apparatus characterized by: A compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, and a radiator that cools the refrigerant discharged from the compression mechanism and an evaporator that heats the refrigerant flowing out of the expansion mechanism are provided. In the refrigeration cycle apparatus, the design volume ratio of the compression mechanism and the expansion mechanism is substantially matched with the largest value among the ratios of the outlet refrigerant densities of the radiator and the evaporator in the operating state of the refrigeration cycle apparatus. A refrigeration cycle apparatus characterized by that. A compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, and a radiator that cools the refrigerant discharged from the compression mechanism and an evaporator that heats the refrigerant flowing out of the expansion mechanism are provided. In the refrigeration cycle apparatus, the outlet volume refrigerant of each of the radiator and the evaporator in the operating state of the refrigeration cycle apparatus in which the refrigerant density at the outlet of the radiator is the largest is the design volume ratio of the compression mechanism and the expansion mechanism. A refrigeration cycle apparatus characterized by substantially matching a density ratio. A compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, and a radiator that cools the refrigerant discharged from the compression mechanism and an evaporator that heats the refrigerant flowing out of the expansion mechanism are provided. In the refrigeration cycle apparatus, the design volume ratio of the compression mechanism and the expansion mechanism is set so that the ambient temperature of the evaporator is the lowest, the water temperature flowing into the radiator is the lowest, and the hot water is allowed to flow out of the radiator. A refrigeration cycle apparatus characterized by substantially matching a ratio of outlet refrigerant densities of the radiator and the evaporator in an operating state of the refrigeration cycle apparatus having the highest temperature. A compression mechanism, an expansion mechanism, and a drive source connected to a single shaft, a radiator that cools the refrigerant discharged from the compression mechanism, and an evaporator that heats the refrigerant flowing out of the expansion mechanism, In the refrigeration cycle apparatus that uses carbon dioxide as a refrigerant and is used as a hot water heater, the design volume ratio of the compression mechanism and the expansion mechanism is 10 or more. A compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, and a radiator that cools the refrigerant discharged from the compression mechanism and an evaporator that heats the refrigerant flowing out of the expansion mechanism are provided. In the refrigeration cycle apparatus, the design volume ratio of the compression mechanism and the expansion mechanism is such that the temperature of the air blown to the evaporator is the lowest, and the temperature of the air blown to the radiator is the lowest, and A refrigeration cycle apparatus characterized in that the ratio of outlet refrigerant densities of the radiator and the evaporator in an operating state of the refrigeration cycle apparatus with the highest temperature of air blown out from the radiator is substantially the same. A compression mechanism, an expansion mechanism, and a drive source connected to a single shaft, a radiator that cools the refrigerant discharged from the compression mechanism, and an evaporator that heats the refrigerant flowing out of the expansion mechanism, A refrigeration cycle apparatus using carbon dioxide as a refrigerant and used as an air conditioner, wherein a design volume ratio of the compression mechanism and the expansion mechanism is 8 or more. A compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, and a radiator that cools the refrigerant discharged from the compression mechanism, an evaporator that heats the refrigerant flowing out of the expansion mechanism, and the expansion A refrigeration cycle apparatus comprising: a bypass flow path that bypasses a mechanism; a bypass valve provided on the bypass flow path; and a pre-reducing valve that depressurizes refrigerant flowing into the expansion mechanism. A control method for a refrigeration cycle apparatus, comprising adjusting a high-pressure side pressure by changing an opening with a valve based on a discharge temperature or a superheat degree of the refrigeration cycle apparatus. A compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, and a radiator that cools the refrigerant discharged from the compression mechanism, an evaporator that heats the refrigerant flowing out of the expansion mechanism, and the expansion In the refrigeration cycle apparatus including a bypass flow path that bypasses the mechanism and a bypass valve provided on the bypass flow path, the opening degree of the bypass valve and the rotational speed of the drive source are determined by discharging the refrigeration cycle apparatus. A control method for a refrigeration cycle apparatus, wherein the high-pressure side pressure is adjusted by changing the temperature or the degree of superheat. A compression mechanism, an expansion mechanism, and a drive source are connected to a single shaft, and a radiator that cools the refrigerant discharged from the compression mechanism, an evaporator that heats the refrigerant flowing out of the expansion mechanism, and the expansion In a refrigeration cycle apparatus including a bypass flow path that bypasses a mechanism, a bypass valve provided on the bypass flow path, and a fan that blows air to the evaporator, the opening degree of the bypass valve and the rotational speed of the fan Is controlled based on the discharge temperature or the degree of superheat of the refrigeration cycle apparatus, thereby adjusting the high-pressure side pressure . The auxiliary compression mechanism and the expansion mechanism are connected to a single shaft, and the compression mechanism that compresses the refrigerant, the auxiliary compression mechanism that further compresses the refrigerant discharged from the compression mechanism, and the auxiliary compression mechanism that is discharged from the auxiliary compression mechanism In the refrigeration cycle apparatus including a radiator that cools the refrigerant and an evaporator that heats the refrigerant that has flowed out of the expansion mechanism, a bypass channel that bypasses the expansion mechanism, and a bypass valve that is provided on the bypass channel And a controller for controlling the operation of the bypass valve, wherein the controller adjusts the high-pressure side pressure by changing the opening of the bypass valve .   The refrigeration cycle apparatus according to claim 13, further comprising a pre-reducing valve that depressurizes the refrigerant flowing into the expansion mechanism. The operating device is, the opening degree of said bypass valve said pre reducing valve, a refrigeration cycle apparatus according to claim 14, wherein the benzalkonium change based on the discharge temperature or superheat of the refrigeration cycle apparatus . The design volume ratio of the auxiliary compression mechanism and the expansion mechanism is approximately matched with the largest value among the ratios of the outlet refrigerant densities of the radiator and the compression mechanism in the operating state of the refrigeration cycle apparatus. The refrigeration cycle apparatus according to claim 13. The design volume ratio of the auxiliary compression mechanism and the expansion mechanism is the ratio of the outlet refrigerant density of each of the radiator and the compression mechanism in the operating state of the refrigeration cycle apparatus in which the refrigerant density at the outlet of the radiator is the largest. The refrigeration cycle apparatus according to claim 13, which is substantially matched. The design volume ratio of the auxiliary compression mechanism and the expansion mechanism is such that the ambient temperature of the evaporator is the lowest, the water temperature flowing into the radiator is the lowest, and the hot water temperature flowing out from the radiator is the highest. 14. The refrigeration cycle apparatus according to claim 13, wherein the refrigeration cycle apparatus is substantially equal to a ratio of outlet refrigerant densities of the radiator and the compression mechanism in an operation state of the refrigeration cycle apparatus. The refrigeration cycle apparatus using carbon dioxide as a refrigerant and being used as a water heater, wherein the design volume ratio of the auxiliary compression mechanism and the expansion mechanism is 4 or more. Cycle equipment.

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