CN1677017A - Refrigeration cycle device and control method thereof - Google Patents

Abstract

The invention provides a refrigeration circulation device and control method thereof. The refrigerating cycle operation is performed without lowering operating efficiency and capacity within various operating ranges by maintaining optimum high-pressure side pressure even if there is a restriction to keep constant a density ratio in a refrigerating cycle device using an expander. This refrigerating cycle device comprises a compression mechanism, an expansion mechanism, a drive source driving the compression mechanism connected to the expansion mechanism through one shaft, a radiator cooling a refrigerant discharged from the compression mechanism, an evaporator heating the refrigerant flowing out from the expansion mechanism, a bypass flow passage bypassing the expansion mechanism, a bypass valve installed in the bypass flow passage, a pre-pressure reducing valve reducing the pressure of the refrigerant flowing into the expansion mechanism, and an operating device controlling the bypass valve and the pre-pressure reducing valve. By operating the degrees of openings of the bypass valve and the pre-pressure reducing valve based on the delivery temperature or the degree of superheat of the refrigerating cycle to control the high-pressure side pressure to a desirable one, an efficient operation can be performed over a wide operating range.

Description

Refrigeration cycle device and control method thereof

technical field

The present invention relates to a refrigeration cycle device with an expander and a control method thereof.

Background technique

Refrigeration cycle devices that use carbon dioxide (hereinafter referred to as CO ₂ ) as a refrigerant that has zero ozone depletion coefficient and a lower global warming coefficient than freons have attracted attention in recent years. However, CO ₂ refrigerant has a critical temperature as low as 31.06°C. In the case of using a temperature higher than this temperature, the high-pressure side of the refrigeration cycle device (compressor outlet ~ radiator ~ pressure reducer inlet) will become a supercritical state where condensation of CO ₂ refrigerant will not occur. Compared with the refrigerant, the operating efficiency (COP) of the refrigeration cycle device is reduced. Therefore, in a refrigerating cycle device using CO ₂ refrigerant, a unit that improves the COP is important.

As such means, a refrigeration cycle has been proposed in which an expander is installed instead of a decompressor, and pressure energy during expansion is recovered as power. Here, in a refrigerating cycle device in which a volumetric compressor and an expander are connected by a single shaft, when the cylinder volume of the compressor is VC and the cylinder volume of the expander is VE, VC/VE (design volume ratio) to determine the ratio of the volumetric circulation flows through the compressor and expander respectively. When the density of the refrigerant at the outlet of the evaporator (refrigerant flowing into the compressor) is taken as DC, and the density of the refrigerant at the outlet of the radiator (refrigerant flowing into the expander) is taken as DE, due to the mass circulation of the compressor and the expander respectively Equally, "VC×DC=VE×DE", that is, the relationship of "VC/VE=DE/DC" is established. Because VC/VE (design volume ratio) is a constant determined during machine design, to keep DE/DC (density ratio) constant, the refrigeration cycle must be balanced. (Hereafter, this point is referred to as "constraint of constant density ratio".)

However, because the operating conditions of the refrigeration cycle device are not necessarily constant, when the design volume ratio assumed at the time of design is different from the density ratio in the actual operating state, due to the "constraint of a certain density ratio", it is difficult to adjust it to be the best Optimum high side pressure.

Therefore, it has been proposed to adjust the structure and control method to the optimum high-pressure side by setting a split flow path for splitting the expander and controlling the amount of refrigerant flowing into the expander (for example, refer to Patent Document 1 (Japanese Patent Laid-Open 2000- 234814) and Patent Document 2 (Japanese Patent Laid-Open No. 2001-116371)).

Contents of the invention

However, in the above-mentioned patent document, when the density ratio in the actual operating state is lower than the design volume ratio, the structure and the configuration and The control method does not describe the configuration and control method for adjusting the optimum high pressure side pressure when the density ratio in the actual operating state is greater than the design volume ratio. In addition, it does not describe how to set the value of the design volume ratio.

In addition, when the density ratio in the actual operating state is lower than the design volume ratio, the amount of refrigerant flowing through the split flow path cannot exceed a certain amount, that is, for the opening of the split valve on the split flow path There is no description of how to do it, such as when the speed becomes the largest. Therefore, when the density ratio in the actual operating state is greater than the design volume ratio, or when the opening of the diverter valve becomes the largest, etc., the optimum high pressure side pressure cannot be adjusted to reduce the operating efficiency of the refrigeration cycle device. question.

Therefore, the purpose of the present invention is to provide a configuration and control method that can be adjusted to the optimum high-pressure side pressure, regardless of whether the density ratio in the actual operating state is greater than or less than the design volume ratio, so as to improve the operating efficiency of the refrigeration cycle device (COP).

Another object of the present invention is to provide a refrigeration cycle apparatus capable of having a design volume ratio for efficient operation in various operating states.

The refrigerating cycle device according to the first aspect of the present invention has a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the drive source through a shaft, and a refrigerant that cools the refrigerant discharged from the expansion mechanism. The evaporator for heating the refrigerant flowing out of the mechanism is characterized by comprising: a split flow path for splitting the flow of the expansion mechanism; a split valve provided on the split flow path; a pre-decompression valve for reducing the pressure of the refrigerant flowing into the expansion mechanism and an operator for controlling the above-mentioned diverter valve and the above-mentioned pre-pressure reducing valve based on the discharge temperature or the degree of superheat.

The refrigerating cycle device according to the second aspect of the present invention has a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the drive source through a shaft, and a radiator that cools the refrigerant discharged from the expansion mechanism. The evaporator heated by the refrigerant flowing out of the mechanism is characterized in that it includes: a split flow path for splitting the flow of the expansion mechanism; a split valve provided on the split flow path; and controlling the split valve and the driving source based on the discharge temperature or the degree of superheat The manipulator of the rotational speed.

The refrigerating cycle device according to the third aspect of the present invention has a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the driving source through a shaft, and cooling the refrigerant from the expansion mechanism. The evaporator is heated by the refrigerant flowing out of the mechanism, and it is characterized in that it includes: a split flow path for splitting the flow of the expansion mechanism; a split valve arranged on the split flow path; a fan for blowing air to the evaporator; An operator that controls the speed of the above-mentioned diverter valve and the above-mentioned fan.

The refrigerating cycle device according to the fourth aspect of the present invention has a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the drive source through a shaft, and a refrigerant that cools the refrigerant discharged from the expansion mechanism. The evaporator heated by the refrigerant flowing out of the mechanism is characterized in that the volume ratio of the above-mentioned compression mechanism and the above-mentioned expansion mechanism and the ratio of the outlet refrigerant densities of the above-mentioned radiator and the above-mentioned evaporator in the operating state of the refrigeration cycle device The largest values are roughly the same.

The refrigerating cycle device according to the fifth aspect of the present invention has a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the driving source through a shaft, and a refrigerant that cools the refrigerant discharged from the expansion mechanism. The evaporator heated by the refrigerant flowing out of the mechanism is characterized in that the radiator and the radiator are in the operating state of the refrigeration cycle device in which the volume ratio of the compression mechanism to the expansion mechanism and the refrigerant density at the outlet of the radiator are maximized. The ratios of refrigerant densities at the respective outlets of the evaporators are substantially the same.

The refrigerating cycle device according to the sixth aspect of the present invention has a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the driving source through a shaft, and a refrigerant that cools the refrigerant discharged from the expansion mechanism. The evaporator heated by the refrigerant flowing out of the mechanism is characterized in that the volume ratio of the compression mechanism and the expansion mechanism is the lowest in the ambient temperature of the evaporator, and the temperature of the water flowing into the radiator is the lowest and flows out of the radiator. The ratio of the refrigerant densities at the respective outlets of the radiator and the evaporator in the operating state of the refrigeration cycle device with the highest hot water temperature is substantially the same.

The refrigerating cycle device according to the seventh aspect of the present invention has a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the drive source through a shaft, and a refrigerant that cools the refrigerant discharged from the expansion mechanism. The evaporator heated by the refrigerant flowing out of the mechanism uses carbon dioxide as the refrigerant and is used as a water heater, and is characterized in that the volume ratio of the compression mechanism to the expansion mechanism is greater than or equal to 10.

The refrigerating cycle device according to the eighth aspect of the present invention has a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the drive source through a shaft, and a refrigerant that cools the refrigerant discharged from the expansion mechanism. The evaporator heated by the refrigerant flowing out of the mechanism is characterized in that the volume ratio of the compression mechanism and the expansion mechanism is the lowest at the temperature of the air blown to the evaporator and the temperature of the air blown to the radiator is the lowest, In addition, the ratio of the refrigerant densities at the outlets of the radiator and the evaporator in an operating state of the refrigeration cycle apparatus in which the temperature of the air blown out from the radiator is the highest is substantially the same.

The refrigerating cycle device according to claim 9 of the present invention is characterized by comprising a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the driving source through a shaft, and The evaporator for heating the refrigerant flowing out of the expansion mechanism uses carbon dioxide as the refrigerant and is used as an air conditioner, wherein the volume ratio of the compression mechanism to the expansion mechanism is 8 or more.

The method for controlling a refrigeration cycle device according to the tenth aspect of the present invention includes a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the driving source through a shaft; An evaporator that heats the refrigerant flowing out of the expansion mechanism; a branch channel that divides the flow from the expansion mechanism; a diverter valve provided on the branch channel; and a pre-pressure reducing valve that decompresses the refrigerant flowing into the expansion mechanism. In the refrigerating cycle apparatus of the present invention, the diverter valve and the preliminary decompression valve are controlled based on the discharge temperature or the degree of superheat.

The control method of the refrigerating cycle device according to the eleventh aspect of the present invention has a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the driving source through a single shaft. ; an evaporator that heats the refrigerant flowing out of the expansion mechanism; a branch channel that divides the flow from the expansion mechanism; The rotational speeds of the above-mentioned diverter valve and the above-mentioned driving source are controlled.

The control method of the refrigerating cycle device according to the twelfth aspect of the present invention includes a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the driving source through a single shaft. ; an evaporator that heats the refrigerant flowing out of the expansion mechanism; a split flow path that splits the flow of the expansion mechanism; a split valve provided on the split flow path; It is characterized in that the rotational speeds of the above-mentioned diverter valve and the above-mentioned fan are controlled based on the discharge temperature or the degree of superheat.

The refrigerating cycle device according to the thirteenth aspect of the present invention has a compression mechanism that compresses a refrigerant while connecting an auxiliary compression mechanism and an expansion mechanism through a shaft; and an auxiliary compressor that recompresses the refrigerant discharged from the compression mechanism. A compression mechanism; a radiator for cooling the refrigerant discharged from the above-mentioned auxiliary compression mechanism and an evaporator for heating the refrigerant flowing out of the above-mentioned expansion mechanism, characterized in that it includes: a split flow path for splitting the flow of the expansion mechanism; diverter valve.

A fourteenth aspect of the present invention is characterized by further comprising a pre-decompression valve for decompressing the refrigerant flowing into the expansion mechanism.

The present invention described in claim 15 further includes an operator for controlling the diverter valve and the pre-decompression valve based on the discharge temperature or the degree of superheat of the refrigeration cycle apparatus.

The sixteenth aspect of the present invention is characterized in that the volume ratio between the auxiliary compression mechanism and the expansion mechanism and the ratio of the refrigerant densities at the outlets of the radiator and the compression mechanism in the operating state of the refrigeration cycle device are maximized. The values are roughly the same.

The seventeenth aspect of the present invention is characterized in that the radiator and the compressor are operated in the operating state of the refrigeration cycle apparatus in which the volume ratio of the auxiliary compression mechanism to the expansion mechanism and the refrigerant density at the outlet of the radiator are maximized. The ratio of refrigerant density at each outlet of the mechanism is approximately the same.

The eighteenth aspect of the present invention is characterized in that the volume ratio between the auxiliary compression mechanism and the expansion mechanism is the lowest at the ambient temperature of the evaporator, the temperature of the water flowing into the radiator is the lowest, and the heat flowing out of the radiator is the lowest. The ratio of the refrigerant densities at the respective outlets of the radiator and the evaporator in an operating state of the refrigeration cycle apparatus having the highest water temperature is substantially the same.

A nineteenth aspect of the present invention is characterized in that in the refrigeration cycle apparatus used as a water heater using carbon dioxide as a refrigerant, the volume ratio of the auxiliary compression mechanism to the expansion mechanism is set to be 4 or more.

The refrigerating cycle device and its control method of the present invention, even in a refrigerating cycle device using an expander that is difficult to adjust to an optimum high-pressure side pressure due to a constant density ratio; Power recovery effect, a refrigeration cycle device capable of efficient operation, and a control method thereof.

Description of drawings

FIG. 1 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a flowchart showing a control method of the refrigeration cycle apparatus according to Embodiment 1 of the present invention.

FIG. 3 is a schematic diagram showing the connection of control units according to Embodiment 1 of the present invention.

Fig. 4 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 2 of the present invention.

FIG. 5 is a flowchart showing a control method of the refrigeration cycle apparatus according to Embodiment 2 of the present invention.

Fig. 6 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 3 of the present invention.

Fig. 7 is a flowchart showing a control method of the refrigeration cycle apparatus according to Embodiment 3 of the present invention.

FIG. 8 is a schematic diagram showing the connection of control units according to Embodiment 3 of the present invention.

Fig. 9 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 4 of the present invention.

Fig. 10 is a flowchart showing a control method of a refrigeration cycle apparatus according to Embodiment 4 of the present invention.

Fig. 11 is a schematic diagram showing the connection of control units according to Embodiment 4 of the present invention.

FIG. 12 is a graph showing the correlation between the density ratio and the COP ratio in Example 5 of the present invention.

Fig. 13 is a graph showing the correlation between density ratio and refrigerant density in Example 5 of the present invention.

Fig. 14 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 6 of the present invention.

Fig. 15 is a graph showing the correlation between the density ratio and the COP ratio of Example 6 of the present invention.

Fig. 16 is a graph showing the correlation between density ratio and refrigerant density in Example 6 of the present invention.

Fig. 17 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 7 of the present invention.

Fig. 18 is a graph showing the correlation between the density ratio and the COP ratio in Example 8 of the present invention.

Fig. 19 is a graph showing the correlation between density ratio and refrigerant density in Example 8 of the present invention.

Detailed ways

The refrigerating cycle apparatus according to Embodiment 1 of the present invention has a branch flow path for branching the expansion mechanism; a branch valve provided on the branch flow path; a pre-decompression valve for reducing the pressure of the refrigerant flowing into the expansion mechanism; Superheat control device for operators of diverter valves and pre-relief valves. According to this embodiment, no matter when the density ratio is smaller than or larger than the design volume ratio, it is possible to provide a pressure regulator that can be adjusted to the required high-pressure side pressure through the opening of the diverter valve and the pre-decompression valve. Refrigeration cycle equipment that operates without reducing operating efficiency and capacity within the scope.

The refrigerating cycle apparatus according to Embodiment 2 of the present invention has a diverter flow path for diverting the expansion mechanism; a diverter valve provided on the diverter flow path; . According to this embodiment, it is possible to adjust the required high-pressure side pressure in the actual operating state by operating the opening degree of the diverter valve and the driving speed of the driving source, and even when the opening degree of the diverter valve is fully open Since the required high side pressure can be adjusted by manipulating the driving speed of the driving source, the operating efficiency and capacity of the refrigeration cycle device can be kept from being reduced in a wide range.

The refrigerating cycle apparatus according to Embodiment 3 of the present invention has a split flow path for splitting the expansion mechanism; a split valve provided on the split flow path; a fan for blowing air to the evaporator; and controlling the split valve and the fan according to the discharge temperature or the degree of superheat. The device of the manipulator of the rotational speed. According to this embodiment, the required high-pressure side pressure can be adjusted under actual operating conditions by operating the opening of the diverter valve and the rotational speed of the fan, and even when the diverter valve is fully open, the By manipulating the rotational speed of the fan, it is possible to adjust to the desired high-pressure side pressure, so that the operation efficiency and capacity of the refrigeration cycle device can be kept from being lowered in a wide range.

According to the refrigeration cycle apparatus according to Embodiment 4 of the present invention, the volume ratio of the compression mechanism and the expansion mechanism substantially coincides with the maximum value among the ratios of the outlet refrigerant densities of the radiator and the evaporator in the operating state of the refrigeration cycle apparatus. installation. According to this embodiment, even if the operating conditions are different, by using a volume ratio that does not pre-expand as much as possible, the seasonal difference in the COP increase rate can be reduced, and the operation of the refrigeration cycle apparatus with high operating efficiency can be maintained at all times.

According to the refrigerating cycle device according to Embodiment 5 of the present invention, the volume ratio between the compression mechanism and the expansion mechanism and the refrigerant density at the outlet of the radiator in the refrigerating cycle device's operating state are maximized in the operating state of the refrigerating cycle device. A device in which the ratio of the outlet refrigerant densities of the radiator and the evaporator is approximately the same. According to this embodiment, even if the operating conditions are different, by using a volume ratio that does not pre-expand as much as possible, the seasonal difference in the COP increase rate can be reduced, and the operation of the refrigeration cycle apparatus with high operating efficiency can be maintained at all times.

According to the refrigeration cycle apparatus according to Embodiment 6 of the present invention, the volume ratio of the compression mechanism and the expansion mechanism is the lowest and the ambient temperature of the evaporator is the lowest, 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. A device in which the ratio of the outlet refrigerant densities of the radiator and the evaporator in the operating state of the circulation device is approximately the same. According to this embodiment, even if the operating conditions are different, by using a volume ratio that does not pre-expand as much as possible, the seasonal difference in the COP increase rate can be reduced, and the operation of the refrigeration cycle apparatus with high operating efficiency can be maintained at all times.

The refrigeration cycle apparatus according to Embodiment 7 of the present invention is an apparatus in which the volume ratio of the compression mechanism and the expansion mechanism is 10 or more. When the refrigeration cycle device is a hot water machine, according to this embodiment, even if the operating conditions are different, by using a volume ratio that does not perform pre-expansion as much as possible, it is possible to reduce the seasonal difference in the COP increase rate and maintain high operation. Efficiency of water heater operation.

According to the refrigeration cycle apparatus according to the eighth embodiment of the present invention, the volume ratio of the compression mechanism and the expansion mechanism is the lowest when 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 is blown out from the radiator. A device in which the ratio of the outlet refrigerant densities of the radiator and the evaporator in the operating state of the refrigeration cycle device with the highest air temperature is substantially the same. According to this embodiment, even if the operating conditions are different, by using a volume ratio that does not pre-expand as much as possible, the seasonal difference in the COP increase rate can be reduced, and the operation of the refrigeration cycle apparatus with high operating efficiency can be maintained at all times.

The refrigeration cycle apparatus according to Embodiment 9 of the present invention is an apparatus in which the volume ratio of the compression mechanism and the expansion mechanism is 8 or more. When the refrigeration cycle device is an air conditioner, according to this embodiment, even if the operating conditions are different, by using a volume ratio that does not perform pre-expansion as much as possible, it is possible to reduce the seasonal difference in the COP increase rate and maintain high operating efficiency. air conditioner.

The control method of the refrigeration cycle apparatus according to Embodiment 10 of the present invention is to have a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the drive source through a shaft; The evaporator that heats the refrigerant flowing out of the expansion mechanism; the split flow path that divides the expansion mechanism; the split valve installed on the split flow path; and the pre-decompression valve that decompresses the refrigerant flowing into the expansion mechanism. A control method that controls the diverter valve and the pre-reducer valve based on the discharge temperature or superheat. According to this embodiment, no matter when the density ratio is less than or greater than the design volume ratio, it can be adjusted to the required high-pressure side pressure through the opening of the diverter valve and the pre-relief valve, and can be used within a wide range. A refrigeration cycle device that operates with reduced operating efficiency and capacity.

The control method of the refrigeration cycle apparatus according to Embodiment 11 of the present invention comprises a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the drive source through a single shaft; An evaporator that heats the refrigerant flowing out of the expansion mechanism; a split flow path that divides the flow from the expansion mechanism; and a refrigeration cycle device with a split valve installed on the split flow path that controls the speed of the split valve and the drive source based on the discharge temperature or degree of superheat Control Method. According to this embodiment, no matter when the density ratio is less than or greater than the design volume ratio, the opening degree of the diverter valve and the rotation speed of the driving source can be adjusted to the required high-pressure side pressure, and even when the diverter valve When the opening is fully open, since the required high-pressure side pressure can be adjusted by operating the rotational speed of the drive source, it can be used within a wide range without reducing the operating efficiency and capacity of the refrigeration cycle device. run.

The control method of the refrigerating cycle device according to the twelfth embodiment of the present invention is to have a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and the driving source through a shaft; An evaporator that heats the refrigerant flowing out of the expansion mechanism; a split flow path that divides the expansion mechanism; a split valve installed on the split flow path; and a refrigeration cycle device that supplies air to the evaporator, based on the discharge temperature or superheat control The control method of the diverter valve and the speed of the fan. According to this embodiment, no matter when the density ratio is less than or greater than the design volume ratio, the opening of the diverter valve and the speed of the fan can be adjusted to the required high-pressure side pressure, and even when the diverter valve When the opening is fully open, the required high side pressure can be adjusted by manipulating the rotation speed of the fan, so it can be operated within a wide range without reducing the operating efficiency and capacity of the refrigeration cycle device.

The refrigerating cycle apparatus according to the thirteenth embodiment of the present invention has a compression mechanism that compresses the refrigerant while connecting the auxiliary compression mechanism and the expansion mechanism through a shaft; and an auxiliary compression mechanism that further compresses the refrigerant discharged from the compression mechanism. ; In the refrigeration cycle device of the radiator that cools the refrigerant discharged from the auxiliary compression mechanism and the evaporator that heats the refrigerant flowing out of the expansion mechanism, there is a split flow path that divides the expansion mechanism and a split valve set on the split flow path installation. According to this embodiment, due to the restriction of a constant density ratio, in a refrigeration cycle device using an expander that is difficult to maintain an optimum high-pressure side pressure, since the change in the density ratio in the actual operating state is small, even if it is different from the designed Assuming that the design volume ratio is different, by operating the opening of the diverter valve, it can also be adjusted to the required high-pressure side pressure, and it can be operated without reducing the operating efficiency and capacity of the refrigeration cycle device.

Embodiment 14 of the present invention is an embodiment in which the refrigeration cycle apparatus according to Embodiment 13 of the present invention includes a pre-decompression valve for decompressing the refrigerant flowing into the expansion mechanism. According to this embodiment, no matter when the density ratio is less than or greater than the design volume ratio, the opening degree of the diverter valve and the pre-relief valve can be adjusted to the required high-pressure side pressure, and the refrigeration cycle device can operating with reduced operating efficiency and capacity.

Embodiment 15 of the present invention is the refrigeration cycle apparatus according to Embodiment 14 of the present invention, which includes an operator for controlling the diverter valve and the preliminary decompression valve based on the discharge temperature or the degree of superheat of the refrigeration cycle apparatus. According to this embodiment, it is possible to adjust the required high-pressure side pressure by manipulating the opening of the diverter valve and the pre-decompression valve, and it is possible to operate the refrigeration cycle apparatus without reducing the operating efficiency and capacity.

In the sixteenth embodiment of the present invention, in the refrigerating cycle apparatus according to the thirteenth embodiment of the present invention, the volume ratio between the auxiliary compression mechanism and the expansion mechanism and the respective outlet refrigerant densities of the radiator and the compression mechanism in the operating state of the refrigerating cycle apparatus are set to A device that is roughly the same as the largest value among them. According to this embodiment, even if the operating conditions are different, by using a volume ratio that does not pre-expand as much as possible, the seasonal difference in the COP increase rate can be reduced, and the operation of the refrigeration cycle apparatus with high operating efficiency can be maintained at all times.

Embodiment 17 of the present invention is the heat radiation in the operating state of the refrigeration cycle apparatus in which the volume ratio between the auxiliary compression mechanism and the expansion mechanism and the refrigerant density at the outlet of the radiator are maximized in the refrigeration cycle apparatus according to Embodiment 13 of the present invention. A device in which the ratio of the outlet refrigerant densities of the compressor and the compression mechanism is approximately the same. According to this embodiment, even if the operating conditions are different, by using a volume ratio that does not pre-expand as much as possible, the seasonal difference in the COP increase rate can be reduced, and the operation of the refrigeration cycle apparatus with high operating efficiency can be maintained at all times.

Embodiment 18 of the present invention is that in the refrigerating cycle apparatus according to Embodiment 13 of the present invention, the volume ratio of the auxiliary compression mechanism and the expansion mechanism is the lowest and the ambient temperature of the evaporator is the lowest, and the temperature of the water flowing into the radiator is the lowest. The ratio of the outlet refrigerant densities of the radiator and the evaporator in the operating state of the refrigeration cycle device with the highest temperature of hot water flowing out of the radiator is approximately the same. According to this embodiment, even if the operating conditions are different, by using a volume ratio that does not pre-expand as much as possible, the seasonal difference in the COP increase rate can be reduced, and the operation of the refrigeration cycle apparatus with high operating efficiency can be maintained at all times.

Embodiment 19 of the present invention is the refrigeration cycle apparatus according to Embodiment 13 of the present invention, in which the volume ratio of the auxiliary compression mechanism and the expansion mechanism of the refrigeration cycle apparatus used as a water heater using carbon dioxide as a refrigerant is 4 or more. When the refrigeration cycle device is a water heater with an auxiliary compression mechanism, according to the present embodiment, it is possible to provide a system that can reduce the increase rate of COP by using a volume ratio that does not perform pre-expansion as much as possible even if the operating conditions are different. The season is poor, and the refrigeration cycle device with high operating efficiency is always maintained.

[Example 1]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 1 of the present invention. In addition, the refrigeration cycle apparatus of this embodiment is demonstrated using the water heater as an example. That is, the present invention is not limited to the water heater of this embodiment, but may be an air conditioner or the like.

The refrigerating cycle device of this embodiment has a refrigerant circulation circuit A composed of a compression mechanism 1, a radiator 2, an expansion mechanism 3, and an evaporator 5 that exchanges heat with the outside air blown by a fan 4, and a feed water pump 6, The hot water supply circulation circuit B constituted by the radiator 2 and the hot water supply tank 7. In the radiator 2, the refrigerant discharged from the compression mechanism 1 is used to heat the water from the feed water pump 6 into hot water, and the hot water is turned into hot water. The refrigerating cycle device (in the case of this embodiment, a hot water supplier) is stored in the hot water supply tank 7 .

The compression mechanism 1 is driven by a drive source 8 such as a motor. In addition, the compression mechanism 1 is connected to an expansion mechanism 3 (expander) that converts pressure energy into power through a shaft 9 , and the input of the drive source 8 is reduced by recovering power of the expansion mechanism 3 . In addition, the refrigerant circulation circuit A has a branch flow channel 10 for dividing the flow of the expansion mechanism 3 , a flow divider valve 11 for adjusting the flow rate flowing through the branch flow channel 10 , and a counter-inflow expansion mechanism provided between the radiator 2 and the inlet of the expansion mechanism 3 . 3 refrigerant pre-decompression pre-decompression valve 12. Carbon dioxide (CO ₂ ) is enclosed as a refrigerant. In addition, there is a discharge temperature detection unit 20 that detects the outlet temperature of the compression mechanism 1 (discharge temperature of the compression mechanism), and a second unit that calculates and operates the opening degrees of the diverter valve 11 and the pre-decompression valve 12 based on the value detected by the discharge temperature detection unit 20. 1 manipulator 21 .

Next, let the cylinder volume of the compression mechanism 1 be VC, the cylinder volume of the expansion mechanism 3 be VE, the outlet refrigerant density of the evaporator 5 be DC (inflow refrigerant density of the compression mechanism 1), and the outlet refrigerant density of the radiator 2 be The operation of the refrigeration cycle apparatus configured as above will be described as DE (inflow refrigerant density of the expansion mechanism 3 ). First, a case where the density ratio (DE/DC) in an actual operating state is approximately equal to the design volume ratio (VC/VE) assumed at the time of design will be described.

The compression mechanism 1 compresses the refrigerant until the critical pressure (high pressure side pressure) is exceeded. The compressed refrigerant is in a state of high temperature and high pressure, and when flowing through the radiator 2, it dissipates heat to water and is cooled. In other words, the water sent from the bottom of the hot water supply tank 7 to the water channel of the radiator 2 by the feed water pump 6 is heated by the refrigerant flowing through the refrigerant channel of the radiator 2 . Thereafter, the refrigerant is decompressed by the expansion mechanism 3 and becomes a gas-liquid two-phase state. The pressure energy of the refrigerant is converted into power in the expansion mechanism 3 , and the power is transmitted to the shaft 9 . Due to the power transmitted to this shaft 9, the input of the drive source 8 is reduced. The refrigerant decompressed by the expansion mechanism 3 flows into the evaporator 5 , and in the evaporator 5 , the refrigerant is cooled by air to become a gas-liquid two-phase or a gaseous state. Thereafter, the refrigerant in a gas-liquid two-phase or gas state is sucked into the compression mechanism 1 again.

The case where the density ratio (DE/DC) in the actual operating state is different from the design volume ratio (VC/VE) assumed at the time of design will be described below. First, the operation when the density ratio (DE/DC) in the actual operating state is larger than the design volume ratio (VC/VE) assumed at the time of design will be described.

In this case, due to the constraint of a certain density ratio, in order to reduce the refrigerant density (DE) at the outlet of the radiator 2 (the inlet of the expansion mechanism 3), the refrigeration cycle is balanced in a state where the pressure on the high pressure side is reduced. . However, in a state where the high-pressure side pressure is lower than the required pressure, the discharge temperature is lowered to lower the heating capability of the refrigeration cycle apparatus and reduce the efficiency of the refrigeration cycle apparatus. Therefore, if the diverter valve 11 is not fully closed, the diverter valve 11 is operated in the closing direction to allow the refrigerant that originally flowed into the diverter channel 10 to flow into the expansion mechanism 3 . Alternatively, if the diverter valve 11 is fully closed, the pre-decompression valve 12 is operated in the closing direction to depressurize the refrigerant flowing into the expansion mechanism 3 and reduce the density of the refrigerant. These operations increase the pressure on the high pressure side, and since it is possible to adjust to a desired pressure, high-efficiency operation can be performed.

Conversely, the operation when the density ratio (DE/DC) in the actual operating state is smaller than the design volume ratio (VC/VE) assumed at the time of design will be described.

In this case, due to the constraint of a constant density ratio, in order to increase the refrigerant density (DE) at the outlet of the radiator 2 (inlet of the expansion mechanism 3), the refrigeration cycle is balanced in a state where the pressure on the high pressure side is increased. . However, in a state where the high-pressure side pressure is higher than the required pressure, the operating efficiency of the refrigeration cycle apparatus decreases. Therefore, if the pre-decompression valve 12 is not fully open, the pre-decompression valve 12 is operated in the opening direction so that the refrigerant flowing into the expansion mechanism 3 is not decompressed and the density of the refrigerant is increased. Alternatively, when the pre-decompression valve 12 is fully open, the diverter valve 11 is operated in the opening direction to allow part of the refrigerant flowing into the expansion mechanism 3 to flow into the diverter flow path 10 . These operations reduce the pressure on the high pressure side, and since it is possible to adjust to a desired pressure, high-efficiency operation can be performed.

As described above, in the refrigerating cycle apparatus of Example 1, due to the restriction of a constant density ratio, in the refrigerating cycle apparatus using an expander that is difficult to maintain an optimum high-pressure side pressure, the density ratio (DE /DC) Whether it is less than or greater than the design volume ratio (VC/VE) assumed in the design, it can be adjusted to the desired high pressure side pressure by operating the opening of the diverter valve 11 and the pre-relief valve 12, To provide a refrigeration cycle device that can be operated without reducing the operating efficiency and capacity.

Next, as a specific method of operating the diverter valve 11 and the pre-decompression valve 12, the control of the first operator 21 will be described based on the flowchart shown in FIG. 2 .

In the control of this embodiment, the correlation between the high-pressure side pressure and the discharge temperature is used, and it is not necessary to use expensive sensors to detect the high-pressure side pressure in the measurement, but the discharge temperature that can be measured relatively cheaply is used to control the diverter valve The diverter valve 11 And pre-decompression valve 12 is controlled.

That is, during operation of the refrigeration cycle apparatus, the detection value (discharge temperature Td) from the discharge temperature detection means 20 is read (step 100). The target discharge temperature (target Td) previously stored in ROM or the like is compared with the discharge temperature read in step 100 (step 110 ).

When the discharge temperature is lower than the target discharge temperature, since the high-pressure side pressure tends to be lower than the optimum pressure, first, it is determined whether the diverter valve 11 is fully closed (step 120). When the diverter valve 11 is fully closed, the pre-decompression valve 12 is operated in the closing direction (step 130), so that the refrigerant flowing into the expansion mechanism 3 is decompressed, the refrigerant density is reduced, and the high-pressure side pressure and discharge temperature are increased. In addition, when the diverter valve 11 is not fully closed, the diverter valve 11 is operated in the closing direction (step 140) to reduce the amount of refrigerant flowing into the diverter passage 10 that divides the expansion mechanism 3, and to reduce the pressure on the high pressure side and the discharge temperature. rise.

Conversely, when the discharge temperature is higher than the target discharge temperature, since the high-pressure side pressure tends to be higher than the optimum pressure, first, it is determined whether the pre-decompression valve 12 is fully opened (step 150). When the pre-decompression valve 12 is fully opened, the diverter valve 11 is operated in the opening direction (step 160), so that the amount of refrigerant flowing into the diverter flow path 10 that divides the expansion mechanism 3 increases, and the high-pressure side pressure and discharge temperature decrease. . In addition, when the pre-decompression valve 12 is not fully opened, the pre-decompression valve 12 is operated in the opening direction (step 170), and the refrigerant flowing into the expansion mechanism 3 is not depressurized and the refrigerant density is not reduced, so that High side pressure and discharge temperature decrease.

After the above steps, return to step 100, and then repeat from step 100 to step 170, as shown in FIG.

As mentioned above, in the control method of the refrigerating cycle device in Embodiment 1, due to the restriction of a certain density ratio, in the refrigerating cycle device using an expander that is difficult to maintain the optimum high pressure side pressure, regardless of the actual operating state When the density ratio (DE/DC) is smaller or larger than the design volume ratio (VC/VE) assumed in the design, the opening degree of the diverter valve 11 and the pre-pressure reducing valve 12 can be adjusted to the required high pressure side based on the discharge temperature The pressure can be operated without reducing the operating efficiency and capacity of the refrigeration cycle device.

In addition, the determination of whether the diverter valve 11 and the pre-decompression valve 12 are fully open or fully closed does not need to be physically fully open or fully closed. Considering the reliability of the valve, etc., it can also be determined by being close to the predetermined value. It can be judged by the maximum opening or minimum opening of fully open or fully closed.

In addition, the refrigerant described in this embodiment is carbon dioxide (CO ₂ ), but other refrigerants such as R410A can also obtain the same effect.

[Example 2]

Next, a refrigeration cycle apparatus according to Embodiment 2 of the present invention will be described. The refrigerating cycle apparatus of this embodiment has substantially the same configuration as that of the refrigerating cycle apparatus of Embodiment 1, and the same functional components are assigned the same reference numerals and their descriptions are omitted. Fig. 4 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 2 of the present invention. In addition, FIG. 5 is a flowchart showing a control method of the refrigeration cycle apparatus according to Embodiment 2 of the present invention.

In the refrigerating cycle apparatus of the present embodiment, the difference from the refrigerating cycle apparatus of Embodiment 1 is that it has an evaporation temperature detection unit that detects the temperature from the inlet to the outlet of the evaporator 5 (evaporating temperature of the evaporator). 30. The suction temperature detection unit 31 that detects the inlet temperature of the compression mechanism 1 (suction temperature of the compression mechanism 1) and calculates the degree of superheat (suction temperature and evaporation temperature) from the values detected by the evaporation temperature detection unit 30 and the suction temperature detection unit 31 Difference), the second manipulator 32 which calculates and operates the opening degrees of the diverter valve 11 and the pre-decompression valve 12 replaces the discharge temperature detection unit 20 and the first manipulator 21 of the first embodiment.

Next, the control performed by the second operator 32 will be described based on the flowchart shown in FIG. 5 . In the control of this embodiment, the correlation between the high-pressure side pressure and the degree of superheat is used, and it is not necessary to use expensive sensors to detect the high-pressure side pressure in the measurement, but to use the evaporating temperature and suction temperature that can be measured relatively cheaply for calculation The degree of superheat of the diverter valve diverter valve 11 and pre-decompression valve 12 are controlled.

That is, during the operation of the refrigeration cycle apparatus, the detection value (evaporation temperature Te) from the evaporation temperature detection means 30 is read (step 200). Then, the detection value (suction temperature Ts) from the suction temperature detection means 31 is read (step 210). Calculate the degree of superheat (SH) as the difference between the suction temperature and the evaporating temperature from these detected values read in (step 220), and combine the target degree of superheat (target SH) previously stored in ROM or the like with the value calculated in step 200. The degree of superheat is compared (step 230).

When the degree of superheat is lower than the target degree of superheat, since the high-pressure side pressure tends to be lower than the optimum pressure, first, it is determined whether the diverter valve 11 is fully closed (step 240 ). When the diverter valve 11 is fully closed, the pre-decompression valve 12 is operated in the closing direction (step 250), so that the refrigerant flowing into the expansion mechanism 3 is decompressed, the refrigerant density is reduced, and the high-pressure side pressure and discharge temperature are increased. In addition, when the diverter valve 11 is not fully closed, the diverter valve 11 is operated in the closing direction (step 260), the amount of refrigerant flowing into the diverter flow path 10 that divides the expansion mechanism 3 is reduced, and the pressure on the high pressure side and the degree of superheat are increased. .

Conversely, when the degree of superheat is higher than the target degree of superheat, since the high-pressure side pressure tends to be higher than the optimum pressure, first, it is determined whether the pre-decompression valve 12 is fully opened (step 270). When the pre-decompression valve 12 is fully open, the diverter valve 11 is operated in the opening direction (step 280) to increase the amount of refrigerant flowing into the diverter passage 10 that diverts the expansion mechanism 3 to reduce the high-pressure side pressure and superheat.

In addition, when the pre-decompression valve 12 is not fully opened, the pre-decompression valve 12 is operated in the opening direction (step 290), and the refrigerant flowing into the expansion mechanism 3 is not decompressed, so that the refrigerant density does not decrease, and the high-pressure side Pressure and discharge temperature decrease.

After the above steps, return to step 200, and then through repeating from step 200 to step 290, the joint control of the diverter valve 11 and the pre-decompression valve 12 is carried out.

As mentioned above, in the refrigerating cycle device and its control method of Embodiment 2, due to the restriction of a certain density ratio, in the refrigerating cycle device using an expander that is difficult to maintain the optimum high pressure side pressure, no matter in the actual operating state When the density ratio (DE/DC) is smaller or larger than the design volume ratio (VC/VE) assumed in the design, by operating the opening of the diverter valve 11 and the pre-decompression valve 12 according to the degree of superheat, it can be adjusted to the required The high side pressure can be operated without reducing the operating efficiency and capacity of the refrigeration cycle device.

In addition, the determination of whether the diverter valve 11 and the pre-decompression valve 12 are fully open or fully closed does not need to be physically fully open or fully closed. Considering the reliability of the valve, etc., it can also be determined by being close to the predetermined value. It can be judged by the maximum opening or minimum opening of fully open or fully closed.

In addition, the refrigerant described in this embodiment is carbon dioxide (CO ₂ ), but other refrigerants such as R410A can also obtain the same effect.

[Example 3]

Next, a refrigeration cycle apparatus according to Embodiment 3 of the present invention will be described. The refrigerating cycle apparatus of this embodiment has substantially the same configuration as that of the refrigerating cycle apparatus of Embodiment 1, and the same functional components are assigned the same reference numerals and their descriptions are omitted. Fig. 6 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 3 of the present invention. Fig. 7 is a flowchart showing a control method of the refrigeration cycle apparatus according to Embodiment 3 of the present invention.

In the refrigerating cycle apparatus of this embodiment, the difference from the refrigerating cycle apparatus of Embodiment 1 is that it does not have the pre-decompression valve 12 of Embodiment 1 but has a drive split based on the value detected by the discharge temperature detection unit 20. The third operator 40 that operates the valve 11 and the rotation speed of the driving source 8 of the compression mechanism 1 .

Next, the control performed by the third operator 40 will be described based on the flow chart shown in FIG. 7 . As in Example 1, control was performed based on the discharge temperature.

That is, during the operation of the refrigeration cycle apparatus, the detection value (discharge temperature) from the discharge temperature detection means 20 is read (step 300). The target discharge temperature stored in ROM or the like in advance is compared with the discharge temperature read in step 300 (step 310).

When the discharge temperature is lower than the target discharge temperature, since the high-pressure side pressure tends to be lower than the optimum pressure, first, it is determined whether the diverter valve 11 is fully closed (step 320 ). When the diverter valve 11 is fully closed, the rotation speed of the drive source 8 is increased (step 330). When the driving speed increases, the circulation amount of the refrigerant discharged from the compression mechanism 1 increases, and because the heat exchange efficiency in the radiator 2 and evaporator 5 decreases, the outlet temperature of the radiator 2 rises, and the refrigerant flowing into the expansion mechanism 3 As the density decreases, the outlet temperature of the evaporator 5 decreases, and because the density of the refrigerant sucked into the compression mechanism 1 increases, the density ratio (DE/DC) decreases. Therefore, the same effect as operating the pre-pressure reducing valve 12 in the closing direction can be obtained, and the high-pressure side pressure and the discharge temperature can be increased.

In addition, when the diverter valve 11 is not fully closed, it is determined whether or not the driving rotation speed is smaller than a predetermined reference value (step 340). When the driving speed is less than the predetermined reference value, because in step 380 described later, it is considered that the driving speed has decreased, by increasing the driving speed (step 350) within the range up to the reference value, the density ratio (DE /DC), so that the pressure on the high pressure side and the discharge temperature rise. In addition, when the driving rotation speed is the reference value, the diverter valve 11 is operated in the closing direction (step 360), the amount of refrigerant flowing into the diverter passage 10 that divides the expansion mechanism 3 is reduced, and the high-pressure side pressure and discharge temperature are increased.

Conversely, when the discharge temperature is higher than the target discharge temperature, since the high-pressure side pressure tends to be higher than the optimum pressure, first, it is determined whether the diverter valve 11 is fully opened (step 370 ). When the diverter valve 11 is fully open, the rotation speed of the driving source 8 is reduced (step 380). When the driving speed decreases, the circulation amount of the refrigerant discharged from the compression mechanism 1 decreases. Since the heat exchange efficiency in the radiator 2 and evaporator 5 is improved, the outlet temperature of the radiator 2 drops, and the refrigerant flowing into the expansion mechanism 3 As the density increases, the outlet temperature of the evaporator 5 increases, and the density ratio (DE/DC) increases because the density of the refrigerant sucked into the compression mechanism 1 decreases. Therefore, an effect equivalent to that of operating the pre-pressure reducing valve 12 in the opening direction can be obtained, and the high-pressure side pressure and the discharge temperature can be lowered.

In addition, when the diverter valve 11 is not fully opened, it is determined whether or not the driving rotation speed is greater than a predetermined reference value (step 390). When the driving speed is greater than a predetermined reference value, because in step 330, it is considered that the driving speed has increased, by reducing the driving speed (step 400) within the range up to the reference value, increasing the density ratio (DE/DC), Reduce the pressure on the high pressure side and the discharge temperature. In addition, when the driving rotation speed is the reference value, the diverter valve 11 is operated in the opening direction (step 410) to increase the amount of refrigerant flowing into the diverter passage 10 that diverts the expansion mechanism 3 to lower the high-pressure side pressure and discharge temperature.

After the above steps, return to step 300, and repeat from step 300 to step 410, as shown in FIG.

As mentioned above, in the refrigerating cycle device and its control method of Embodiment 3, due to the restriction of a certain density ratio, in the refrigerating cycle device using an expander that is difficult to maintain the optimum high pressure side pressure, no matter in the actual operating state When the density ratio (DE/DC) of the volume ratio (DE/DC) is smaller or larger than the design volume ratio (VC/VE) assumed at the time of design, the opening degree of the diverter valve 11 and the driving speed of the driving source 8 can be adjusted based on the discharge temperature. Required high side pressure.

In addition, as shown in Figure 8, even when the opening degree of the diverter valve 11 is fully open, the required high-pressure side pressure can be adjusted by operating the driving speed of the driving source 8, and the refrigeration system can be operated without freezing. Operate when the operating efficiency and capacity of the circulation device are reduced.

In addition, in this embodiment, an example of controlling based on the discharge temperature as in the first embodiment has been described, but it is also possible to perform control based on the degree of superheat as in the second embodiment. In addition, the opening degree manipulation of the pre-decompression valve 12 in Embodiments 1 and 2 and the driving speed manipulation of the drive source 8 in this embodiment may be implemented in combination. In addition, in determining whether the diverter valve 11 is fully open or fully closed, the valve does not need to be fully open or fully closed physically. Considering the reliability of the valve, etc., it can also be determined by being close to the predetermined fully open or fully closed. It can be judged by the maximum opening or the minimum opening of the closed. In addition, the refrigerant described in this embodiment is carbon dioxide (CO ₂ ), but other refrigerants such as R410A can also obtain the same effect.

[Example 4]

Next, a refrigeration cycle apparatus according to Embodiment 4 of the present invention will be described. The refrigerating cycle apparatus of this embodiment has substantially the same configuration as that of the refrigerating cycle apparatus of Embodiment 1, and the same functional components are assigned the same reference numerals and their descriptions are omitted. Fig. 9 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 4 of the present invention. Fig. 10 is a flowchart showing a control method of a refrigeration cycle apparatus according to Embodiment 4 of the present invention.

In the refrigerating cycle apparatus of this embodiment, the difference from the refrigerating cycle apparatus of Embodiment 1 is that it does not have the pre-decompression valve 12 of Embodiment 1 but has a drive split based on the value detected by the discharge temperature detection unit 20. The valve 11 and the fourth operator 50 for operating the rotational speed of a drive source (not shown) that drives the fan 4 .

Next, the control performed by the fourth operator 50 will be described based on the flowchart shown in FIG. 10 . In the control of the present embodiment, as in the first embodiment, control is performed based on the discharge temperature.

That is, during operation of the refrigeration cycle apparatus, the detection value (discharge temperature) from the discharge temperature detection means 20 is read (step 400). The target discharge temperature stored in ROM or the like in advance is compared with the discharge temperature read in step 400 (step 410).

When the discharge temperature is lower than the target discharge temperature, since the high-pressure side pressure tends to be lower than the optimum pressure, first, it is determined whether the diverter valve 11 is fully closed (step 420 ). When the diverter valve 11 is fully closed, the rotation speed of the fan 4 is increased (step 430). Because the evaporation pressure (the pressure at the inlet of the evaporator 5 to the inlet of the compression mechanism 1) increases when the fan speed increases, the refrigerant density at the outlet of the evaporator 5 increases, and the density ratio (DE/DC) decreases. Therefore, the same effect as operating the pre-pressure reducing valve 12 in the closing direction can be obtained, and the high-pressure side pressure and the discharge temperature can be increased.

In addition, when the diverter valve 11 is not fully closed, it is determined whether or not the fan rotation speed is lower than a predetermined reference value (step 440). When the fan speed is less than a predetermined reference value, because in step 480 described later, it is considered that the fan speed has decreased, by increasing the fan speed (step 450) within the range up to the reference value, the density ratio (DE /DC), so that the pressure on the high pressure side and the discharge temperature rise. In addition, when the fan rotation speed is at the reference value, the diverter valve 11 is operated in the closing direction (step 460) to reduce the amount of refrigerant flowing into the diverter passage 10 that diverts the expansion mechanism 3 to increase the high-pressure side pressure and discharge temperature.

Conversely, when the discharge temperature is higher than the target discharge temperature, since the high-pressure side pressure tends to be higher than the optimum pressure, first, it is determined whether the diverter valve 11 is fully open (step 470). When the diverter valve 11 is fully open, the driving rotation speed of the fan 4 is reduced (step 480). Since the evaporation pressure decreases when the fan speed decreases, the refrigerant density at the outlet of the evaporator 5 decreases, and the density ratio (DE/DC) increases. Therefore, an effect equivalent to that of operating the diverter valve 11 in the opening direction can be obtained, and the high-pressure side pressure and the discharge temperature can be lowered.

In addition, when the diverter valve 11 is not fully opened, it is determined whether or not the fan rotation speed is greater than a predetermined reference value (step 490). When the driving speed is greater than a predetermined reference value, because in step 430, the fan speed is considered to have increased, by reducing the fan speed (step 500) within the range up to the reference value, increasing the density ratio (DE/DC), Reduce the pressure on the high pressure side and the discharge temperature. In addition, when the driving rotation speed is the reference value, the diverter valve 11 is operated in the opening direction (step 510) to increase the amount of refrigerant flowing into the diverter passage 10 that diverts the expansion mechanism 3 to lower the high-pressure side pressure and discharge temperature.

After the above steps, return to step 400, and then repeat from step 400 to step 510, as shown in FIG.

As mentioned above, in the refrigerating cycle device and its control method of Embodiment 4, due to the restriction of a certain density ratio, in the refrigerating cycle device using an expander that is difficult to maintain the optimum high pressure side pressure, no matter in the actual operating state When the density ratio (DE/DC) is smaller or larger than the design volume ratio (VC/VE) assumed in the design, the opening degree of the diverter valve 11 and the speed of the fan 4 can be adjusted to the required value based on the degree of superheat. High side pressure.

In addition, as shown in Figure 11, even if the opening degree of the diverter valve 11 is fully open, the required high-pressure side pressure can be adjusted by operating the rotation speed of the fan 4, and the refrigeration cycle device can operating with reduced operating efficiency and capacity.

In addition, in the present embodiment, an example of controlling based on the discharge temperature is described as in the first embodiment, but it is also possible to perform control based on the degree of superheat as in the second embodiment. In addition, it is also possible to combine the operation of the opening degree of the pre-decompression valve 12 in the first and second embodiments, the operation of the driving rotation speed of the compression mechanism 11 in the third embodiment, and the operation of the rotation speed of the fan 4 in this embodiment. In addition, in determining whether the diverter valve 11 is fully open or fully closed, the valve does not need to be fully open or fully closed physically. Considering the reliability of the valve, etc., it can also be determined by being close to the predetermined fully open or fully closed. It can be judged by the maximum opening or the minimum opening of the closed. In addition, the refrigerant described in this embodiment is carbon dioxide (CO ₂ ), but other refrigerants such as R410A can also obtain the same effect.

[Example 5]

Next, a refrigeration cycle apparatus according to Embodiment 5 of the present invention will be described. In addition, since the structure and control method of the refrigeration cycle apparatus of this embodiment are the same as those of Embodiment 1, description of the same structure and operation is omitted.

The structure of the refrigeration cycle device of this embodiment is characterized in 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 of the radiator 2 is When the refrigerant density is DE, the value of the design volume ratio (VC/VE) and the density ratio (DE/DC) under the condition that the density ratio (DE/DC) in the actual operating state becomes the maximum are approximately the same in design. In addition, specifically, it is designed so that the value of the density ratio (DE/DC) under the condition where the outlet refrigerant density (DE) of the radiator 2 becomes a maximum substantially coincides.

In addition, in the refrigerating cycle device used as a water heater, the design volume ratio (VC/VE) is within the range of use of the water heater, where the ambient temperature (outside air temperature) of the evaporator 5 is the lowest, and the inflow heat dissipation It is a feature of the design structure that the density ratio (DE/DC) during operation under the condition that the water temperature (inlet water temperature) of the radiator 2 is the lowest and the hot water temperature (hot water outlet temperature) flowing out of the radiator 2 is the highest is approximately the same.

In addition, specifically, in a refrigeration cycle apparatus used as a water heater, a design volume ratio (VC/VE) value of 10 or more is characteristic of a design structure.

However, in the refrigeration cycle apparatus of this embodiment, as described in Embodiment 1, when the density ratio (DE/DC) in the actual operating state is smaller than the design volume ratio (VC/VE) determined at the time of design, By operating the diverter valve 11 in the opening direction or when the density ratio (DE/DC) is greater than the design volume ratio (VC/VE), by operating the pre-decompression valve 12 in the opening direction, the density ratio (DE/DC) and the design volume The ratio (VC/VE) is consistent and can be adjusted to the required high side pressure. However, when the amount of refrigerant flowing through the branch channel 10 increases or the pre-expansion pressure difference increases by the pre-decompression valve 12, the power that should be recoverable decreases, and the improvement rate of the operating efficiency (COP) decreases. Therefore, how to design the design volume ratio to the optimum value is very important.

Therefore, the best design volume ratio for the occasion of using the refrigerating cycle device of this embodiment as a water heater will be described in detail below with reference to Figs. 12 and 13 .

FIG. 12 is a correlation diagram showing the density ratio and COP ratio of Example 5 of the present invention, and FIG. 13 is a correlation diagram showing the density ratio and refrigerant density of Example 5 of the present invention.

In FIG. 12, the outside air temperature is set in the order of high temperature: summer period, middle period, winter period and low temperature period. The water inlet temperature is the minimum temperature assumed according to each external air temperature condition, and the hot water outlet temperature is the standard temperature assumed according to each external air temperature condition. In addition, the COP ratio assumes that the COP of a refrigeration cycle apparatus that does not use an expander is 100 under each outside air temperature condition. Hereinafter, the summer season conditions will be described as an example.

In summer period conditions, the density ratio (DE/DC) in the actual operating state is about 7. In the case of a refrigeration cycle apparatus designed with a design volume ratio (VC/VE) larger than this value, it is necessary to divert the refrigerant to the diverting flow path 10 under summer conditions. Conversely, in the case of a refrigeration cycle device designed with a design volume ratio (VC/VE) smaller than this value, the refrigerant must be pre-expanded by the pre-decompression valve 12 under summer conditions. However, it is known that in either case of diversion and pre-expansion, the COP ratio is lower than that of the case where the design volume ratio (VC/VE) is designed to be about 7 when the optimal design is carried out under summer conditions. In particular, the COP ratio drops dramatically in the case of pre-expansion.

On the other hand, the density ratio (DE/DC) in the actual operating state was about 10 and about 12 under the conditions of the winter period and the low temperature period, respectively. In the case of a refrigerating cycle device designed with a design volume ratio (VC/VE) greater than these values, it is necessary to divert the refrigerant to the diverting channel 10 under winter conditions and low temperature conditions. Conversely, in the case of a refrigeration cycle device designed with a design volume ratio (VC/VE) smaller than these values, the refrigerant must be pre-expanded by the pre-decompression valve 12 under winter conditions and low temperature conditions. However, it is known that in either case of flow splitting and pre-expansion, optimal design is carried out under the conditions of the winter period and the low temperature period, that is, when the design volume ratio (VC/VE) is designed to be about 10 Compared with the case of about 12, the COP ratio is lowered, and especially in the case of pre-expansion, the COP ratio is sharply and greatly lowered.

That is to say, due to different operating conditions such as seasons, the optimal design volume ratio is different. In the refrigeration cycle device in which the compression mechanism 1 and the expansion mechanism 3 are directly connected by a shaft 9, the design volume ratio (VC/VE) is different in the design. Only one value can be determined. Thus, for example, a design that is optimal for summer period conditions with a design volume ratio (VC/VE) of about 7 would have a COP ratio of about 112 for summer period conditions, but a COP ratio of about 112 for other seasonal conditions. 101-103.

On the other hand, when the design volume ratio (VC/VE) is about 12, which is the best design in the low temperature period, the COP ratio is about 110 in the low temperature period, and about 107 in other seasons. ~108. Alternatively, in the case where the design volume ratio (VC/VE) that is optimal under winter period conditions is about 10, the COP ratio is about 103 in the short low temperature period during the comparison period, but it is 110 under winter period conditions, at About 108 in other seasonal conditions.

In this way, when the design volume ratio (VC/VE) is designed to be optimal under the conditions of the winter period and the low temperature period, the seasonal difference in the COP increase rate can be reduced, and it can always be maintained even if the operating conditions such as seasons are different. High operating efficiency.

That is, in the refrigerating cycle apparatus of Example 5, as can be seen from FIG. 12 , focusing on the fact that the rate of increase in COP is smaller when pre-expansion is performed compared with the case of splitting, by setting the design volume ratio (VC/VE) It is designed so that the value of the density ratio (DE/DC) is approximately the same as the value of the density ratio (DE/DC) under the condition where the value of the density ratio (DE/DC) in the actual operating state is the largest (in the case of Fig. Even under different conditions, pre-expansion is not performed as much as possible, and the operation of the high-efficiency refrigeration cycle apparatus can always be maintained.

In addition, 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, it can be known that the density ratio (DE/DC) is related to the evaporator 5 Compared with the change of the outlet refrigerant density (DC), it is more affected by the change of the outlet refrigerant density (DE) of the radiator 2, and furthermore, it is roughly proportional to the outlet refrigerant density (DE) of the radiator 2.

Therefore, by designing the design volume ratio (VC/VE) of the refrigerating cycle device of the present embodiment to be the condition with the maximum value of the density ratio (DE/DC) in the actual operating state, that is, the outlet of the radiator 2 When the value of the density ratio (DE/DC) under the condition where the refrigerant density (DE) becomes the maximum is substantially the same, the operation of the refrigeration cycle apparatus with high operating efficiency can always be maintained.

In addition, as already explained in Fig. 12, because in the refrigerating cycle apparatus used as a hot water machine, the ambient temperature (outside air temperature) of the evaporator 5 is the lowest and the air flowing into the radiator 2 is the lowest within the scope of use. The condition that the water temperature (inlet water temperature) is the lowest and the hot water temperature (hot water outlet temperature) flowing out of the radiator 2 is the highest (low temperature period conditions in the case of Fig. 12 ) is different from the actual operating state of the refrigeration cycle device The density ratio (DE/DC) is equivalent to operating under the maximum condition, so by designing the density ratio (DE/DC) in this operating state to be approximately the same as the design volume ratio (VC/VE), the The operation of the refrigeration cycle apparatus with high operating efficiency can always be maintained.

In addition, the density ratio (DE/DC) in the actual operating state of the refrigerating cycle device is the largest condition, and when the refrigerating cycle device is a water heater, the ambient temperature of the evaporator 5 is the lowest and flows into the radiator 2. The condition that the temperature of the water is the lowest and the temperature of the hot water flowing out from the radiator 2 is the highest is equivalent. When it is applied to a general refrigeration cycle device including an air conditioner described later, it can be replaced by the fluid that heats the refrigerant in the evaporator 5. The temperature of the fluid is the lowest. , and the temperature of the fluid flowing into the radiator 2 for cooling the refrigerant in the radiator 2 is the lowest, and the temperature of the fluid flowing out of the radiator 2 heated by cooling by the refrigerant is the highest.

In addition, in the refrigerating cycle device used as a water heater, the design volume ratio (VC/VE) is designed so that the design volume ratio (VC/VE) becomes a value equal to or greater than 10 (a value corresponding to the winter season condition and the low temperature period condition in the case of Fig. 12 ), the operation of the refrigeration cycle device with high operating efficiency can always be maintained.

[Example 6]

Next, a refrigeration cycle apparatus according to Embodiment 6 of the present invention will be described using an example of an air conditioner instead of the water heater according to Embodiment 1. FIG. Fig. 14 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 6 of the present invention. In addition, since the structure of the refrigeration cycle apparatus of this Example is substantially the same as that of Example 1, the same code|symbol is used for the same functional part. Therefore, the description of the same configuration and its operation is omitted. In addition, since the control method of the refrigeration cycle apparatus is the same as that of Embodiment 1, its description is omitted.

The refrigerating cycle apparatus of this embodiment is composed of an outdoor unit C and an indoor unit D. As shown in FIG. Therefore, the outdoor unit C is composed of a compression mechanism 1, a first four-way valve 60, an outdoor heat exchanger 62 for exchanging heat with air blown by an outdoor fan 61, a second four-way valve 63, an expansion mechanism 3, and the like. , the indoor unit D is configured with an indoor heat exchanger 65 that exchanges heat with the air blown by the indoor fan 64, and the like.

Therefore, in the refrigeration cycle apparatus of this embodiment, when the first four-way valve 60 and the second four-way valve 63 are switched to the solid line direction in the drawing, the outdoor heat exchanger 62 is used as a radiator, so that The indoor heat exchanger 65 is used as an evaporator, and the room where the indoor unit D is installed can be made into a cold room. In addition, when the first four-way valve 60 and the second four-way valve 63 are switched to the dotted line direction in the figure, the indoor heat exchanger 65 is used as a radiator and the outdoor heat exchanger 62 is used as an evaporator. It is possible to make the room where the indoor unit D is installed into a warm room and perform air conditioning operations.

In addition, the structure of the present embodiment is characterized in that when the cylinder volume of the compression mechanism 1 is taken as VC, the cylinder volume of the expansion mechanism 3 is taken as VE, and either the outdoor heat exchanger 62 or the indoor heat exchanger 65 is used as the evaporation The outlet refrigerant density of the heat exchanger when the heat exchanger is used as DC (inflow refrigerant density of the compression mechanism 1), and the outlet refrigerant of the heat exchanger when either the outdoor heat exchanger 62 or the indoor heat exchanger 65 is used as a radiator When the density is DE (inflow medium density of the expansion mechanism 3), the density ratio (DE /DC) are roughly the same. In addition, specifically, it is designed so that the outlet refrigerant density (DE) of the heat exchanger when either the outdoor heat exchanger 62 or the indoor heat exchanger 65 is used as a radiator becomes the maximum density ratio. The value of (DE/DC) roughly agrees with this.

In addition, in the refrigeration cycle device used as an air conditioner, the design volume ratio (VC/VE) is the same as that in the outdoor heat exchanger 62 or indoor heat exchanger 65 used as an evaporator within the range of use of the air conditioner. The temperature of the air blown by any one of the heat exchangers is the lowest, and the temperature of the air blown by the heat exchanger of any one of the outdoor heat exchanger 62 or the indoor heat exchanger 65 used as a radiator is the lowest, and the temperature of the air sent to the heat exchanger is the lowest It is a characteristic of the design structure that the density ratio (DE/DC) during operation under the condition of the highest temperature of the air blown out by the heat exchanger used as a radiator is approximately the same.

In addition, specifically, in a refrigeration cycle apparatus used as an air conditioner, a design volume ratio (VC/VE) value of 8 or more is characteristic of a design structure.

The optimal design volume ratio for using the refrigeration cycle device of this embodiment as an air conditioner will be described in detail below with reference to Figures 15 and 16 .

FIG. 15 is a correlation diagram showing the density ratio and COP ratio of Example 6 of the present invention, and FIG. 16 is a correlation diagram showing the density ratio and refrigerant density of Example 6 of the present invention.

In FIG. 15, the outside air temperature is set in the order of higher temperature: cool room in summer, cool room in the middle period, warm room in the middle period, and warm room in winter period. 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 out from the indoor heat exchanger 65 ) are standard temperatures set according to the respective outside air temperature conditions. In addition, the COP ratio assumes that the COP of a refrigeration cycle apparatus that does not use an expander is 100 under each outside air temperature condition. Hereinafter, description will be given by taking the cooling room conditions in summer as an example.

The density ratio (DE/DC) in the actual operating state is about 4 in cold room conditions in the summer period. In the case of a refrigerating cycle device designed with a design volume ratio (VC/VE) greater than this value, it is necessary to divert the refrigerant to the diverting flow path 10 under cool room conditions in summer. Conversely, in the case of a refrigerating cycle device designed with a design volume ratio (VC/VE) smaller than this value, the refrigerant must be pre-expanded by the pre-decompression valve 12 under cold room conditions in summer. However, it is known that in either case of diversion and pre-expansion, the COP is lower than the case where the design volume ratio (VC/VE) is designed to be about 4 when the optimal design is performed under cold room conditions in summer. In particular, in the case of pre-expansion, the COP ratio drops sharply and greatly.

On the other hand, the density ratio (DE/DC) in the actual operating state is about 8 to 9 under the heating conditions in the middle period and the heating conditions in the winter period, respectively. In the case of a refrigerating cycle device designed with a design volume ratio (VC/VE) greater than these values, it is necessary to divert the refrigerant to the branch flow path 10 under heating conditions in the middle period and heating conditions in the winter period. Conversely, in the case of a refrigerating cycle device designed with a design volume ratio (VC/VE) smaller than these values, the refrigerant must be pre-expanded by the pre-decompression valve 12 under the heating conditions in the middle period and the heating conditions in the winter period. However, it is known that in either case of split flow and pre-expansion, the optimal design is performed under each condition of the heating conditions in the middle period and the heating conditions in the winter period, that is, when the design volume ratio (VC/VE) is designed as Compared with the case of about 8 to 9, the COP ratio is lowered, and especially in the case of pre-expansion, the COP ratio is sharply and significantly lowered.

That is to say, due to different operating conditions such as seasons, the optimal design volume ratio is different. In the refrigeration cycle device in which the compression mechanism 1 and the expansion mechanism 3 are directly connected by a shaft 9, the design volume ratio (VC/VE) is different in the design. Only one value can be determined. Therefore, for example, in the case where the design volume ratio (VC/VE) is about 4 which is optimal for the cool room conditions in the summer period, the COP ratio is about 130 in the cool room conditions in the summer period, but in the warm room conditions in the middle period and in winter Under the conditions of greenhouse during the period, the COP ratio is about 102-104.

On the other hand, when the design volume ratio (VC/VE) is about 8 to 9, which is optimal under the heating conditions in the middle period and the heating conditions in the winter period, the COP ratio under the heating conditions in the middle period and the heating conditions in the winter period It is about 111, but the COP ratio is about 113 to 114 under the cold room conditions in the summer period and the cold room conditions in the middle period.

In this way, when the design volume ratio (VC/VE) is designed to be optimal under the heating conditions in the middle period and the heating conditions in the winter period, the seasonal difference in the COP increase rate can be reduced, and the operating conditions such as seasons are different. Always maintain high operating efficiency.

That is, in the refrigerating cycle apparatus of Example 6, as can be seen from FIG. 15 , focusing on the fact that the rate of increase in COP is smaller when pre-expansion is performed compared with the case of splitting, by setting the design volume ratio (VC/VE) It is designed so that the value of the density ratio (DE/DC) approximately matches the value of the density ratio (DE/DC) under the condition where the value of the density ratio (DE/DC) in the actual operating state is the largest (in the case of FIG. Even if the operating conditions are different, pre-expansion is not performed as much as possible, and the operation of the refrigeration cycle device with high operating efficiency can always be maintained.

In addition, from the outlet refrigerant density (DC) when either the outdoor heat exchanger 62 or the indoor heat exchanger 65 is used as an evaporator shown in FIG. The relationship between the outlet refrigerant density (DE) and the density ratio (DE/DC) when any one of them is used as a radiator, it can be known that the density ratio (DE/DC) is related to the change of the outlet refrigerant density (DC) of the evaporator The ratio is more affected by the change of the outlet refrigerant density (DE) of the radiator 2, and furthermore, is approximately proportional to the outlet refrigerant density (DE) of the radiator 2.

Therefore, in the refrigerating cycle device of the present embodiment, by designing its design volume ratio (VC/VE) to be the condition with the maximum value of the density ratio (DE/DC) under the actual operating state, that is, the condition with the radiator The value of the density ratio (DE/DC) under the condition that the outlet refrigerant density (DE) becomes the maximum is approximately the same, and the operation of the refrigeration cycle device with high operating efficiency can always be maintained.

In addition, as already explained in Fig. 15, because in the refrigerating cycle device used as an air conditioner, within its scope of use, in the outdoor heat exchanger 62 or indoor heat exchanger 65 used as an evaporator The temperature of the air blown by any one heat exchanger is the lowest, and the temperature of the air blown by the heat exchanger of any one of the outdoor heat exchanger 62 or the indoor heat exchanger 65 used as a radiator is the lowest, and the temperature of the air sent to the user is the lowest. The case where the temperature of the air blown out of the heat exchanger used as a radiator is the highest, and the case where the density ratio (DE/DC) in the actual operating state is the largest (the winter period in the case of Fig. 15 Heating conditions) are equivalent, so by designing the density ratio (DE/DC) in this operating state to be approximately the same as the design volume ratio (VC/VE), the operation of the refrigeration cycle device with high operating efficiency can always be maintained.

In addition, in the refrigerating cycle device used as an air conditioner, the design volume ratio (VC/VE) is designed so that the design volume ratio (VC/VE) becomes a value greater than or equal to 8 (values corresponding to the heating conditions in the winter period and the heating conditions in the middle period in the case of Fig. 15 ), the operation of the refrigeration cycle device with high operating efficiency can always be maintained.

[Example 7]

Next, a refrigeration cycle apparatus according to Embodiment 7 of the present invention will be described. Fig. 17 is a configuration diagram showing a refrigeration cycle apparatus according to Embodiment 7 of the present invention. In addition, since the structure of the refrigeration cycle apparatus of this Example is substantially the same as that of Example 1, the same code|symbol is used for the same functional part, and the description is abbreviate|omitted. In addition, since the control method of the refrigerating cycle apparatus is also the same as that of Embodiment 1, its description is omitted. In addition, the refrigeration cycle apparatus of this embodiment is demonstrated using the water heater as an example.

The refrigeration cycle apparatus of the present embodiment is composed of a refrigerant circulation circuit A and a hot water supply circulation circuit B. The refrigerant circulation circuit A has a drive source 71 such as an electric motor, a compression mechanism 72 driven by the drive source 71, an auxiliary compression mechanism 73 for recompressing the refrigerant discharged from the compression mechanism 72, a radiator 2, an expansion mechanism 74, and a fan. The evaporator 5 etc. which carry out heat exchange with the external air which blows wind. In addition, the hot water supply circuit B has the same structure as that of the first embodiment, and includes the feed water pump 6, the radiator 2, the hot water supply tank 7, and the like. In addition, the auxiliary compression mechanism 73 is a structure in which a shaft 75 is connected to an expansion mechanism 74 that converts pressure energy into power, and is driven by recovered power of the expansion mechanism 74 .

Next, let the cylinder volume of the auxiliary compression mechanism 73 be VCs, the cylinder volume of the expansion mechanism 74 be VE, the outlet refrigerant density of the compression mechanism 72 be DCs (inflow medium density of the auxiliary compression mechanism 73), and the outlet of the radiator 2 be The refrigerant density will be described as DE (inflow medium density of the expansion mechanism 3) for the operation of the refrigeration cycle apparatus configured as described above. First, a case where the density ratio (DE/DCs) in an actual operating state is approximately equal to the design volume ratio (VC/s/VE) assumed at the time of design will be described.

The compression mechanism 72 compresses the refrigerant up to a pressure (intermediate pressure) exceeding the critical pressure. The compressed refrigerant is then compressed to the high pressure side by the auxiliary compression mechanism 73 . Then, when the refrigerant in a high-temperature and high-pressure state flows through the radiator 2, it dissipates heat to the water and is cooled. Thereafter, the refrigerant is decompressed by the expansion mechanism 74 and becomes a gas-liquid two-phase state. The pressure energy of the refrigerant is converted into power in the expansion mechanism 74 , and the power is transmitted to the shaft 75 . The auxiliary compression mechanism 73 is driven by power transmitted to this shaft 75 . The refrigerant decompressed by the expansion mechanism 74 flows into the evaporator 5 , and in the evaporator 5 , the refrigerant is cooled by air to become a gas-liquid two-phase or a gaseous state. Thereafter, the refrigerant in a gas-liquid two-phase or gas state is sucked into the compression mechanism 72 again.

The case where the density ratio (DE/DCs) in the actual operating state is different from the design volume ratio (VCs/VE) assumed at the time of design will be described below. First, the operation when the density ratio (DE/DCs) in the actual operating state is larger than the design volume ratio (VCs/VE) assumed at the time of design will be described.

In this case, due to the constraint of a constant density ratio, in order to reduce the refrigerant density (DE) at the outlet of the radiator 2 (the inlet of the expansion mechanism 74), the refrigeration cycle is balanced in a state where the pressure on the high pressure side is reduced. . However, when the pressure on the high pressure side is lower than the required pressure, the discharge temperature is lowered to lower the heating capability of the refrigeration cycle apparatus, and the efficiency of the refrigeration cycle apparatus is reduced. Therefore, if the diverter valve 11 is not fully closed, the diverter valve 11 is operated in the closing direction, so that the refrigerant that originally flowed into the diverter channel 10 flows into the expansion mechanism 74 . Alternatively, if the diverter valve 11 is fully closed, the pre-decompression valve 12 is operated in the closing direction to depressurize the refrigerant flowing into the expansion mechanism 74 and reduce the density of the refrigerant. Through these operations, the pressure on the high pressure side is increased, and since the desired pressure can be adjusted, high-efficiency operation can be performed.

Conversely, the operation when the density ratio (DE/DCs) in the actual operating state is smaller than the design volume ratio (VCs/VE) assumed at the time of design will be described.

In this case, due to the constraint of a constant density ratio, the refrigeration cycle is balanced with the pressure on the high pressure side raised in order to increase the refrigerant density (DE) at the outlet of the radiator 2 (inlet of the expansion mechanism 74). However, in a state where the high-pressure side pressure is higher than the required pressure, the operating efficiency of the refrigeration cycle apparatus decreases. Therefore, if the pre-decompression valve 12 is not fully open, the pre-decompression valve 12 is operated in the opening direction to increase the density of the refrigerant without depressurizing the refrigerant flowing into the expansion mechanism 74 . Alternatively, when the pre-decompression valve 12 is fully open, the diverter valve 11 is operated in the opening direction to allow part of the refrigerant flowing into the expansion mechanism 74 to flow into the diverter flow path 10 . Through these operations, the pressure on the high pressure side is reduced, and since the desired pressure can be adjusted, high-efficiency operation can be performed.

As described above, in the refrigerating cycle apparatus of Example 7, due to the restriction of the constant density ratio, in the refrigerating cycle apparatus using an expander that is difficult to maintain the optimum high-pressure side pressure, regardless of the density ratio ( DE/DCs) is less than or greater than the design volume ratio (VCs/VE) assumed in the design, it can be adjusted to the desired high pressure side pressure by operating the opening of the diverter valve 11 and the pre-decompression valve 12 , to provide a refrigerating cycle device that can be operated without reducing the operating efficiency and capacity.

In addition, the discharge temperature of the refrigeration cycle in this embodiment is the outlet temperature of the auxiliary compression mechanism 73 , and the degree of superheat of the refrigeration cycle is the difference between the suction temperature of the compression mechanism 72 and the evaporation temperature of the evaporator 5 .

[Example 8]

Next, a refrigeration cycle apparatus according to Embodiment 8 of the present invention will be described. Since the configuration and control method of the refrigeration cycle apparatus of this embodiment are the same as those of Embodiment 7, descriptions of the same configuration, operations, and the like are omitted.

The structure of this embodiment is characterized in 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 DE. , the value of the design volume ratio (VCs/VE) is roughly consistent with the value of the density ratio (DE/DCs) under the condition that the density ratio (DE/DCs) in the actual operating state becomes the maximum. In addition, specifically, it is designed so that the value of the density ratio (DE/DCs) substantially coincides with the value of the density ratio (DE/DCs) under the condition which the outlet refrigerant density (DE) of the radiator 2 becomes the maximum.

In addition, in the refrigerating cycle device used as a water heater, the design volume ratio (VCs/VE) is within the operating range of the water heater, where the ambient temperature (outside air temperature) of the evaporator 5 is the lowest, and the inflow heat dissipation It is a feature of the design structure that the density ratio (DE/DCs) during operation under the condition that the water temperature (inlet water temperature) of the radiator 2 is the lowest and the temperature of the hot water flowing out of the radiator 2 (hot water outlet temperature) is the highest is approximately the same.

In addition, specifically, in a refrigerating cycle apparatus used as a water heater, a design volume ratio (VCs/VE) value of 3.5 or more is characteristic of the design structure.

However, in the refrigerating cycle apparatus of this embodiment, as described in Embodiment 1, when the density ratio (DE/DCs) in the actual operating state is smaller than the design volume ratio (VCs/VE) determined at the time of design, By operating the diverter valve 11 in the opening direction or when the density ratio (DE/DCs) is greater than the design volume ratio (VCs/VE), by operating the pre-relief valve 12 in the opening direction, the density ratio (DE/DCs) and the design volume The ratio (VCs/VE) is consistent and can be adjusted to the required high side pressure. However, when the amount of refrigerant flowing through the branch channel 10 increases or the pre-expansion pressure difference increases by the pre-decompression valve 12, the power that should be recoverable decreases, and the improvement rate of the operating efficiency (COP) decreases. Therefore, how to design the design volume ratio to the optimum value is very important.

Therefore, the optimum design volume ratio for the occasion of using the refrigerating cycle device of this embodiment as a water heater will be described in detail below with reference to Figs. 18 and 19 .

FIG. 18 is a correlation diagram showing the density ratio and COP ratio in Example 8 of the present invention, and FIG. 19 is a correlation diagram showing the density ratio and refrigerant density in Example 8 of the present invention.

In FIG. 18, the outside air temperature is set in the order of high temperature: summer period, middle period, winter period, and low temperature period. The water inlet temperature is the minimum temperature assumed according to each external air temperature condition, and the hot water outlet temperature is the standard temperature assumed according to each external air temperature condition. In addition, the COP ratio assumes that the COP of a refrigeration cycle apparatus that does not use an expander is 100 under each outside air temperature condition. Hereinafter, the summer season conditions will be described as an example.

In summer period conditions, the density ratio (DE/DCs) in the actual operating state is about 4.1. In the case of a refrigeration cycle device designed with a design volume ratio (VCs/VE) greater than this value, it is necessary to divert the refrigerant to the diverting flow path 10 under summer conditions. Conversely, in the case of a refrigeration cycle device designed with a design volume ratio (VCs/VE) smaller than this value, the refrigerant must be pre-expanded by the pre-decompression valve 12 under summer conditions. However, it is known that the COP ratio decreases in both the split flow and the pre-expansion, compared to the optimal design under summer conditions, that is, when the design volume ratio (VCs/VE) is designed to be about 4.1 , especially in the case of pre-expansion, the COP ratio drops dramatically.

On the other hand, the density ratios (DE/DCs) in the actual operating state were about 4.3 and about 4.5 under the winter period conditions and the low temperature period conditions, respectively. In the case of a refrigeration cycle device designed with a design volume ratio (VCs/VE) greater than these values, it is necessary to divert the refrigerant to the branch flow path 10 under winter conditions and low temperature conditions. Conversely, in the case of a refrigerating cycle device designed with a design volume ratio (VCs/VE) smaller than these values, the refrigerant must be pre-expanded by the pre-decompression valve 12 under winter conditions and low temperature conditions. However, it is known that in either case of flow splitting and pre-expansion, it is best to design under the conditions of winter period conditions and low temperature period conditions, that is, when the design volume ratio (VCs/VE) is set to about 4.3 Compared with the case of about 4.5, the COP ratio is lowered, and especially in the case of pre-expansion, the COP ratio is sharply and greatly lowered.

That is to say, due to different operating conditions such as seasons, the optimal design volume ratio is different. In the refrigeration cycle device in which the auxiliary compression mechanism 73 and the expansion mechanism 74 are directly connected by a shaft 75, the design volume ratio (VCs/VE) is between Only one value can be decided at design time. Thus, for example, a design with a design volume ratio (VCs/VE) of about 4.1 that is optimal for summer period conditions would have a COP ratio of about 112 for summer period conditions, but a COP ratio of about 112 for other seasonal conditions. for 105.

On the other hand, when the optimal design volume ratio (VCs/VE) is about 4.5 in the low temperature period, the COP ratio is about 110 in the low temperature period and about 110 in other seasons. ~111. Alternatively, it is the same when designing the optimum design volume ratio (VCs/VE) under winter period conditions.

In this way, when the design volume ratio (VCs/VE) is designed to be optimal under the conditions of the winter period and the low temperature period, the seasonal difference in the COP increase rate can be reduced, and it can always be maintained even if the operating conditions such as seasons are different. High operating efficiency.

That is, in the refrigerating cycle apparatus of Example 8, as can be seen from FIG. 18 , focusing on the fact that the increase rate of COP is smaller when the pre-expansion is performed compared with the case where the flow is divided, by setting the design volume ratio (VCs/VE) It is designed so that the value of the density ratio (DE/DCs) is approximately the same as the value of the density ratio (DE/DCs) under the maximum value in the actual operating state (in the case of Figure 18, the low temperature period condition), so that even if the Depending on the conditions, pre-expansion may not be performed, and the operation of the high-efficiency refrigeration cycle apparatus can always be maintained.

In addition, 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), it can be known that the density ratio (DE/DCs) It is more affected by the change of the outlet refrigerant density of the radiator 2 than the change of the outlet refrigerant density (DCs) of the compression mechanism 71 , and is approximately proportional to the outlet refrigerant density (DE) of the radiator 2 .

Therefore, by designing the design volume ratio (VCs/VE) of the refrigerating cycle device of the present embodiment to be the condition with the maximum value of the density ratio (DE/DCs) in the actual operating state, that is, the outlet of the radiator 2 The value of the density ratio (DE/DCs) under the condition that the refrigerant density (DE) becomes the maximum is substantially the same, and the operation of the refrigeration cycle apparatus with high operating efficiency can be maintained at all times.

In addition, as already explained in Fig. 18, because in the refrigerating cycle apparatus used as a hot water machine, the ambient temperature (outside air temperature) of the evaporator 5 is the lowest and the air flowing into the radiator 2 is The condition of operating under the condition that the water temperature (inlet water temperature) is the lowest and the hot water temperature (hot water outlet temperature) flowing out of the radiator 2 is the highest (the low temperature period condition in the case of Fig. 18 ) is different from the actual operating state of the refrigeration cycle device The density ratio (DE/DC) is equivalent to operating under the maximum condition, so by designing the density ratio (DE/DCs) in this operating state to be approximately the same as the design volume ratio (VCs/VE), the The operation of the refrigeration cycle apparatus with high operating efficiency can always be maintained.

In addition, in the refrigerating cycle apparatus used as a water heater having the auxiliary compression mechanism 73, the design volume ratio (VCs/VE) is designed to be a value of 4 or more (similar to the conditions of the summer season in the case of FIG. 18 , the intermediate Period conditions, winter period conditions, and low temperature period conditions basically all correspond to the value), it is possible to always maintain the operation of the refrigeration cycle device with high operating efficiency.

In addition, according to the configuration of this embodiment, as shown in Fig. 18, compared with Fig. 12 of Embodiment 5, since the change in the volume ratio due to different operating conditions such as seasons becomes smaller, high operating efficiency can always be maintained. operation of the refrigeration cycle unit.

In other words, in the refrigerating cycle apparatus having the auxiliary compression mechanism 73, in order to reduce the change in the volume ratio in the actual operating state, even if it is different from the design volume ratio assumed at the time of design, only the opening degree of the diverter valve 11 is adjusted. It can also be adjusted to the required high-pressure side pressure, and can be operated without reducing the operating efficiency and capacity of the refrigeration cycle device. That is, only the diverter valve 11 may be configured without the pre-decompression valve 12, and even in the case of only the diverter valve 11, it is preferable to adopt a value larger than the design volume ratio set at the time of design.

The refrigeration cycle device and its control method of the present invention are applicable to hot water supply devices (water heaters), household air conditioners, commercial air conditioners, vehicle air conditioners (automotive air conditioners), and the like. Therefore, a high power recovery effect can be obtained over a wide operating range, and a refrigeration cycle apparatus operating at high efficiency can be provided. In particular, the effect is large in a refrigeration cycle apparatus in which the high-pressure side of a refrigeration cycle using carbon dioxide can be in a supercritical state.

Claims (19)

1. A refrigeration cycle device having a radiator that cools the refrigerant discharged from the above-mentioned compression mechanism while connecting a compression mechanism, an expansion mechanism, and a drive source through a shaft, and heating the refrigerant that flows out from the above-mentioned expansion mechanism An evaporator characterized by comprising: a diverting flow path for diverting the expansion mechanism; A shunt valve arranged on the above-mentioned shunt flow path; a pre-decompression valve for decompressing the refrigerant flowing into the expansion mechanism; and An operator that controls the above-mentioned diverter valve and the above-mentioned pre-pressure reducing valve based on the discharge temperature or the degree of superheat. 2. A refrigeration cycle device having a radiator that cools the refrigerant discharged from the above-mentioned compression mechanism while connecting a compression mechanism, an expansion mechanism, and a drive source through a shaft, and heating the refrigerant that flows out of the above-mentioned expansion mechanism An evaporator characterized by comprising: a diverting flow path for diverting the expansion mechanism; A diverter valve arranged on the diverter flow path; and An operator that controls the rotational speed of the diverter valve and the drive source based on the discharge temperature or the degree of superheat. 3. A refrigerating cycle device having a radiator that cools the refrigerant discharged from the above-mentioned compression mechanism while connecting a compression mechanism, an expansion mechanism, and a drive source through a shaft, and heating the refrigerant that flows out from the above-mentioned expansion mechanism An evaporator characterized by comprising: a diverting flow path for diverting the expansion mechanism; A shunt valve arranged on the above-mentioned shunt flow path; a fan for supplying air to said evaporator; and An operator that controls the rotation speed of the above-mentioned diverter valve and the above-mentioned fan based on the discharge temperature or the degree of superheat. 4. A refrigeration cycle device having a radiator that cools the refrigerant discharged from the above-mentioned compression mechanism while connecting the compression mechanism, the expansion mechanism, and a driving source through a shaft, and heating the refrigerant that flows out of the above-mentioned expansion mechanism The evaporator is characterized in that: The volume ratio of the compression mechanism and the expansion mechanism is substantially equal to the maximum value among the ratios of the respective outlet refrigerant densities of the radiator and the evaporator in an operating state of the refrigeration cycle apparatus. 5. A refrigerating cycle device having a radiator that cools the refrigerant discharged from the compression mechanism while connecting a compression mechanism, an expansion mechanism, and a drive source through a shaft, and heating the refrigerant that flows out of the expansion mechanism The evaporator is characterized in that: The volume ratio of the compression mechanism and the expansion mechanism is substantially equal to the ratio of the refrigerant densities at the outlets of the radiator and the evaporator in an operating state of the refrigeration cycle apparatus in which the refrigerant density at the outlet of the radiator is maximum. 6. A refrigeration cycle device having a radiator that cools the refrigerant discharged from the above-mentioned compression mechanism while connecting a compression mechanism, an expansion mechanism, and a driving source through a shaft, and heating the refrigerant that flows out of the above-mentioned expansion mechanism The evaporator is characterized in that: The volume ratio of the above-mentioned compression mechanism and the above-mentioned expansion mechanism is the same as that in the operating state of the refrigeration cycle device in which the ambient temperature of the above-mentioned evaporator is the lowest, the temperature of the water flowing into the above-mentioned radiator is the lowest, and the temperature of the hot water flowing out of the above-mentioned radiator is the highest. The ratio of the refrigerant densities at the respective outlets of the radiator and the evaporator is substantially the same. 7. A refrigerating cycle device having a radiator that cools the refrigerant discharged from the above-mentioned compression mechanism while connecting a compression mechanism, an expansion mechanism, and a driving source through a shaft, and heating the refrigerant that flows out of the above-mentioned expansion mechanism The evaporator uses carbon dioxide as a refrigerant and is used as a hot water machine, and is characterized in that: Make the volume ratio of the above-mentioned compression mechanism and the above-mentioned expansion mechanism greater than or equal to 10. 8. A refrigerating cycle device having a radiator that cools the refrigerant discharged from the compression mechanism while connecting a compression mechanism, an expansion mechanism, and a drive source through a shaft, and heating the refrigerant that flows out of the expansion mechanism The evaporator is characterized in that: A refrigerating cycle device in which the volume ratio between the compression mechanism and the expansion mechanism is the lowest when the temperature of the air blown to the evaporator is the lowest, the temperature of the air blown to the radiator is the lowest, and the temperature of the air blown from the radiator is the highest The ratio of the refrigerant densities at the respective outlets of the radiator and the evaporator in the operating state is approximately the same. 9. A refrigeration cycle device, characterized in that it has a radiator that cools the refrigerant discharged from the above-mentioned compression mechanism while connecting the compression mechanism, the expansion mechanism, and the driving source through a shaft, and that flows out of the above-mentioned expansion mechanism. An evaporator that is heated by a refrigerant, uses carbon dioxide as a refrigerant and is used as an air conditioner, and is characterized in that: Make the volume ratio of the compression mechanism and the expansion mechanism greater than or equal to 8. 10. A control method for a refrigeration cycle device, comprising a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and a driving source through a shaft; The evaporator that heats the refrigerant; the split flow path that divides the expansion mechanism; the split valve provided on the split flow path; and the pre-decompression valve that depressurizes the refrigerant flowing into the expansion mechanism. It is characterized by: The above-mentioned diverter valve and the above-mentioned preliminary pressure reducing valve are controlled based on the discharge temperature or the degree of superheat. 11. A control method for a refrigeration cycle device, comprising a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and a driving source through a shaft; The evaporator for heating the refrigerant; the split flow path for splitting the above-mentioned expansion mechanism; the refrigeration cycle device with a split valve provided on the split flow path, characterized in that: The rotational speeds of the diverter valve and the driving source are controlled based on the discharge temperature or the degree of superheat. 12. A control method for a refrigeration cycle device, comprising a radiator that cools the refrigerant discharged from the compression mechanism while connecting the compression mechanism, the expansion mechanism, and a driving source through a shaft; An evaporator for heating the refrigerant; a split flow path for splitting the expansion mechanism; a split valve provided on the split flow path; and a refrigeration cycle device for a fan blowing air to the evaporator, characterized in that: The rotational speeds of the diverter valve and the fan are controlled based on the discharge temperature or the degree of superheat. 13. A refrigeration cycle device, comprising a compression mechanism for compressing a refrigerant while connecting an auxiliary compression mechanism and an expansion mechanism through a shaft; an auxiliary compression mechanism for recompressing the refrigerant discharged from the compression mechanism; cooling from the auxiliary The radiator for the refrigerant discharged from the compression mechanism and the evaporator for heating the refrigerant flowing out of the expansion mechanism are characterized by comprising: a diverting flow path for diverting the expansion mechanism; A diverter valve provided on the diverter flow path. 14. The refrigerating cycle device according to claim 13, further comprising: A pre-pressure reducing valve for reducing the pressure of the refrigerant flowing into the above-mentioned expansion mechanism. 15. The refrigerating cycle device according to claim 14, further comprising: An operator of the diverter valve and the pre-decompression valve is controlled based on the discharge temperature or the degree of superheat of the refrigeration cycle apparatus. 16. The refrigeration cycle device according to claim 13, characterized in that: A volume ratio between the auxiliary compression mechanism and the expansion mechanism is substantially equal to a maximum value among ratios of refrigerant densities at outlets of the radiator and the compression mechanism in an operating state of the refrigeration cycle apparatus. 17. The refrigeration cycle device according to claim 13, characterized in that: The volume ratio of the auxiliary compression mechanism and the expansion mechanism is substantially equal to the ratio of the refrigerant densities at the outlets of the radiator and the compression mechanism in an operating state of the refrigeration cycle apparatus in which the outlet of the radiator has the largest refrigerant density. 18. The refrigeration cycle device according to claim 13, characterized in that: When the volume ratio of the auxiliary compression mechanism and the expansion mechanism is set to the lowest ambient temperature of the evaporator, 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. The ratio of the refrigerant densities at the respective outlets of the above-mentioned radiator and the above-mentioned evaporator is approximately the same. 19. The refrigeration cycle device according to claim 13, characterized in that: In the refrigeration cycle apparatus used as a water heater using carbon dioxide as a refrigerant, the volume ratio of the auxiliary compression mechanism to the expansion mechanism is set to be 4 or more.

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