TWI522585B - Refrigeration unit and freezer unit - Google Patents

Description

Freezer and freezer unit

The present invention relates to a refrigeration unit and a refrigerator unit that sequentially connect a compressor, a condenser, a pressure reducing mechanism, and an evaporator to form a refrigeration cycle, and more particularly to a liquid refrigerant cooling circuit.

Such a technique is described in, for example, Japanese Laid-Open Patent Publication No. 2009-109065 (Patent Document 1). In the prior art, a liquid refrigerant cooling line (a first liquid injection line) and a medium pressure liquid injection line (a second liquid injection line) are provided, wherein the liquid refrigerant cooling line is to be A part of the high-pressure refrigerant of the main circulation of the refrigeration cycle is taken out and decompressed, and the reduced-pressure refrigerant is injected into the intermediate pressure portion of the compressor.

In the above-mentioned conventional technique, in particular, the liquid refrigerant cooling pipe is used to cool the liquid refrigerant to a temperature lower than the ambient temperature, whereby the refrigeration capacity can be improved even if the circulation amount of the refrigerant flowing to the low pressure machine side is the same.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-109065

The refrigeration system of Patent Document 1 described above uses a variable displacement compressor that can change the driving frequency as a compressor (compression device). 1. The volume variable type compressor is controlled to adjust the refrigeration capacity according to the load of the refrigeration cycle; and when the refrigeration capacity is to be increased, the valve provided in the liquid refrigerant cooling line is opened to be cooled by using the liquid refrigerant. Pipeline.

However, Patent Document 1 basically controls the variable displacement compressor to adjust the refrigeration capacity, and the drive frequency of the variable displacement compressor is controlled in response to the load. In order to obtain the necessary refrigeration capacity, the compressor is driven at a high number of revolutions, so that the operating current is increased and the burden on the compressor is increased. As a result, the reliability of the compressor is lowered, and the power consumption is also increased, and the COP (Coefficient of Performance) cannot be sufficiently improved, and there is insufficient consideration for energy saving.

An object of the present invention is to provide a refrigerating apparatus and a refrigerating unit capable of reducing the fluctuation of the operating volume of the compression apparatus and stabilizing even when the load of the refrigeration cycle fluctuates, and obtaining the necessary refrigerating capacity and reducing the load on the compressor. The reliability is improved, and the drive current of the compressor is also suppressed from rising to save energy.

In order to achieve the above object, the present invention provides a refrigerating apparatus including a refrigerating cycle which is sequentially connected by a refrigerant pipe to be: a compression device capable of controlling a volume; and a condenser for compressing the compression device a high-pressure refrigerant condensing; and a pressure-reducing mechanism for decompressing the high-pressure refrigerant condensed in the condenser; and an evaporator for evaporating the low-pressure refrigerant decompressing the pressure-reducing mechanism; the refrigeration device characterized by having: a liquid refrigerant Cooling pipeline The liquid refrigerant which is obtained by extracting a part of the high-pressure liquid refrigerant circulating in the main line of the refrigeration cycle and depressurizing the refrigerant, supercools the liquid refrigerant flowing through the main line, and cools the liquid refrigerant of the main line. The reduced pressure refrigerant is injected into the intermediate pressure portion of the compressor; and the flow rate control means is configured to control the flow rate of the liquid refrigerant flowing through the liquid refrigerant cooling line and to depressurize the pressure; and the controller, in response to the load of the main line The flow rate control means is controlled by the controller, and the controller controls the flow rate control means when the refrigeration capacity is required to be increased in response to a load fluctuation of the main line, or when the refrigeration capacity must be reduced. After controlling the freezing capacity, if it is necessary to control the freezing capacity by the volume control of the aforementioned compression device, the volume control of the compressor is performed.

Another feature of the present invention is a chiller unit comprising: a compression device for controlling a volume; and a condenser for condensing a high pressure refrigerant compressed by the compression device; and being coupled to the low pressure machine to constitute a refrigeration cycle, the low pressure machine a pressure reducing mechanism for decompressing a high pressure refrigerant condensed in the condenser; and an evaporator for evaporating a low pressure refrigerant decompressing the pressure reducing mechanism; the refrigerator unit characterized by comprising: a liquid refrigerant The cooling pipe is obtained by extracting a part of the high-pressure liquid refrigerant from the refrigerant pipe as the main pipe of the refrigeration cycle and depressurizing the refrigerant, and cooling the liquid refrigerant flowing through the main pipe. The reduced pressure refrigerant that has cooled the liquid refrigerant of the main line is injected into the intermediate pressure portion of the compressor, and the flow rate control means controls the flow rate of the liquid refrigerant flowing through the liquid refrigerant cooling line to be decompressed; and a controller Detecting a load fluctuation of the main line, and controlling the flow rate control means; the controller must increase the refrigeration capacity in response to a load change of the main line In either case, when it is necessary to reduce the refrigeration capacity, after controlling the flow rate control means to control the refrigeration capacity, if it is necessary to control the refrigeration capacity by the volume control of the compression device, Volume control of the compressor system.

According to the present invention, even if the load of the refrigeration cycle fluctuates, the fluctuation in the operating volume of the compression device can be reduced and stabilized, and the necessary refrigeration capacity can be obtained. Therefore, the load on the compression device can be reduced and the load can be reduced. The reliability is improved, and the drive current of the compression device can be suppressed from rising to save energy.

Specific embodiments of the present invention will be described below based on the drawings.

[Example 1]

BRIEF DESCRIPTION OF THE DRAWINGS

In Fig. 1, I is a refrigerating apparatus I, which is composed of a refrigerator unit II installed outside the house, and a low-pressure machine III installed in the room and connected to the refrigerator unit by a refrigerant pipe. In the present embodiment, the low-pressure machine III is, for example, a display rack that cools a cooling object such as a food product installed in a store such as a supermarket. Such display racks generally have a large variation in load. Further, the low-pressure machine III is not limited thereto, and other types of refrigerators or freezers, or indoor units of air conditioners are also applicable, and the number of low-pressure machines may be connected in parallel in a plurality of stages.

The freezing device 1 of the present embodiment is sequentially connected: a compressor (compression device) 1 as a compression device capable of controlling the volume; and an oil separator 2 (Oil Separator) for compressing the high pressure at the compressor 1 The refrigerator oil contained in the refrigerant is separated; and the condenser 3 condenses the high-pressure refrigerant separated in the oil separator 2; and the pressure reducing mechanism 7 decompresses the high-pressure refrigerant condensed in the condenser 3; Evaporator 8 to make the reduction The pressure mechanism 7 decompresses the low pressure refrigerant to evaporate; thus constitutes the main line of the refrigeration cycle.

The compressor 1 compresses a low-temperature low-pressure gas refrigerant into a high-temperature high-pressure gas refrigerant. The high-temperature high-pressure gas refrigerant compressed by the compressor 1 contains refrigerating machine oil. Therefore, the refrigerant and the refrigerating machine oil are separated by the oil separator 2. The high-temperature high-pressure gas refrigerant separated by the oil separator 2 is condensed by the condenser 3 to become a high-temperature high-pressure liquid refrigerant. The high-pressure liquid refrigerant after the condensation is depressurized by the pressure reducing mechanism 7, and is evaporated by the evaporator 8, and becomes a low-temperature low-pressure gas refrigerant to return to the compressor 1.

The pressure reducing mechanism 7 is constituted by an expansion valve or the like, and is provided in the low pressure machine III together with the evaporator 8 described above.

Further, as the compressor 1, in this embodiment, a variable displacement compressor which can change the driving frequency is used. In this way, the variable displacement compressor can be controlled to adjust the refrigeration capacity in response to the load of the refrigeration cycle. Further, as the compressor (compression device) 1, for example, a variable displacement scroll compressor or a rotary compressor controlled by an inverter or a screw compressor or the like is used. When a plurality of the compressors 1 are provided, it is also possible to combine a plurality of fixed-volume compressors (fixed-speed compressors) without using a variable-capacity compressor, and to control the volume by the number of stages. A compression device; or a combination of a variable displacement compressor and a fixed displacement compressor to produce a controllable volume compression device.

As the refrigerant, an HFC system (for example, R404A or R410A) is used.

In the present embodiment, on the downstream side of the condenser 3, a liquid receiver 4 is provided to accommodate the refrigerant from the condenser 3, and on the downstream side of the liquid receiver 4, an air supercooling heat exchanger 5 is disposed. The liquid refrigerant discharged from the liquid receiver 4 is subjected to heat exchange with air to be supercooled. As a result, it is possible to effectively prevent bubbles from occurring in the piping before the evaporator 8 (that is, so-called flashing occurs). As a result, it is possible to suppress the change in the flow rate of the refrigerant introduced into the supercooling heat exchanger 6 to be described later, and to adjust the freezing ability. The condenser 3 and the air supercooling heat exchanger 5 are constituted by a Cross Fin Type Heat Exchanger in the present embodiment, and are ventilated by the cooling fan 60 with the outside air.

Further, in the main line of the refrigeration cycle, a decompression refrigerant is provided, in which a part of the high-pressure refrigerant circulating in the main line is taken out and pre-decompressed; and the supercooling heat exchanger 6 is circulated with the main line. The high pressure refrigerant exchanges heat. The supercooling heat exchanger 6 is disposed on the downstream side of the condenser 3. Further, the supercooling heat exchanger 6 is disposed on the downstream side of the liquid receiver 4 and the air subcooling heat exchanger 5.

The supercooling heat exchanger 6 includes a first flow path 6a as a main line and a second flow path 6b which is branched from the main line, and is constituted by, for example, a plate heat exchanger, and is configured to be in the first The refrigerant flowing through the flow path 6a exchanges heat with the refrigerant flowing through the second flow path 6b.

Further, the high-pressure refrigerant that exchanges heat in the supercooling heat exchanger 6 is extracted from between the condenser 3 and the supercooling heat exchanger 6, specifically, from the air subcooling heat exchanger 5 and supercooling. The heat exchanger 6 is drawn out. However, it is not limited thereto, and it may be pumped from the aforementioned liquid receiver 4. Alternatively, it may be taken out from the downstream side of the supercooling heat exchanger 6.

In the supercooling heat exchanger 6, the decompressed refrigerant that has undergone heat exchange with the high-pressure refrigerant circulating in the main line is injected into the intermediate pressure portion of the compressor 1 via the liquid refrigerant cooling line 41. That is, an injection port is formed in the intermediate pressure portion of the compressor 1, and the liquid refrigerant from the liquid refrigerant cooling line 41 is injected from the injection port. A flow rate control valve (flow rate control means) 11 such as an electronic expansion valve is provided in the liquid refrigerant cooling line 41 to control the amount of refrigerant injected into the intermediate pressure portion of the compressor 1. The flow rate control valve 11 is provided as a pressure reducing means for adjusting the flow rate, and is disposed between the point branched from the main line and the subcooling heat exchanger 6. The liquid refrigerant cooling line 41 is provided to control the degree of subcooling of the subcooling heat exchanger 6 to adjust the refrigeration capacity.

Further, in the present embodiment, in addition to the liquid refrigerant cooling line 41 described above, a liquid injection line 42 for preventing the temperature rise of the compressor is provided. In the present embodiment, the liquid injection line 42 has one end side connected to the refrigerant pipe of the main line, the refrigerant pipe of the main line, and the air subcooling heat exchanger 5 and the subcooler heat exchanger 6 described above. The other end side is connected to the liquid refrigerant cooling line 41, and is connected to the intermediate pressure portion of the compressor 1 by the same piping as the liquid refrigerant cooling line 41. Further, the liquid injection line 42 is provided with a decompression means 9 which is composed of an electronic expansion valve or a pressure reducer such as a capillary tube and an on-off valve. This decompression means is controlled in accordance with the temperature of the discharge gas discharged from the compressor 1 or the degree of superheat of the discharge gas.

One end side of the liquid refrigerant cooling line 41 or the liquid injection line 42, It is not necessarily connected to the upstream side of the aforementioned subcooler heat exchanger 6, but may be connected to the downstream side thereof.

Reference numeral 17 denotes a return line for returning the oil separated in the oil separator 2 to the refrigerant pipe on the suction side of the compressor 1, and a pressure reducing means 10 is provided in the oil return line 17. As the decompression means 10, a combination of an on-off valve and a pressure reducer in a capillary tube or the like is used.

Further, a refrigerant pressure sensor 14 is provided in the refrigerant pipe on the suction side of the compressor 1, and a discharge gas temperature sensor 15 and a discharge pressure sensor 19 are provided in the refrigerant pipe on the discharge side of the compressor 1. The discharge gas temperature sensor 15 detects the temperature of the discharge gas from the compressor to detect the temperature of the compressor 1. Further, the degree of superheat can be obtained based on the detected values of the discharge gas temperature sensor 15 and the discharge pressure sensor 19. Further, in the present embodiment, the refrigerant pipe 18 on the downstream side of the supercooling heat exchanger 6 is provided with a liquid temperature sensor 18 for detecting the temperature of the liquid refrigerant cooled by the supercooling heat exchanger 6.

The signals of the sensors 14, 15, 18, 19 are input to a controller (control means) 16, and the controller 16 is configured to control the compressor and the liquid refrigerant cooling circuit according to the input signals and the like. The flow rate control valve 11 of 41, the pressure reducing means 9 of the liquid injection line 42, the pressure reducing means 10 of the oil return line 17, and the like.

The suction pressure sensor 14 is provided to detect the load of the main line (the load of the low pressure machine III), which detects the pressure on the suction side of the compressor 1.

Next, the basic motion of the aforementioned main road will be described using FIG. 1 and FIG. Work. 2 is a Mollier diagram of the refrigeration apparatus of FIG. 1.

The gas refrigerant sucked into the compressor 1 is compressed in the compressor 1 to be discharged as a high-temperature, high-pressure gas refrigerant. The discharged gas refrigerant passes through the oil separator 2, exothermicly exchanges heat with the outdoor air (outside air) in the condenser 3, and is thereby condensed and flows into the liquid receiver 4 for storage. The liquid refrigerant stored in the liquid receiver 4 is guided to the subcooler 5, where it is again cooled by heat exchange with the outdoor air.

When there is no refrigerant flowing through the liquid refrigerant cooling line 41 or the liquid injection line 42, the entire amount of the liquid refrigerant supercooled in the subcooler 5 is guided to the first flow path 6a of the supercooling heat exchanger 6. . Further, when the flow rate control valve 11 is opened, a part of the liquid refrigerant is branched from the main line, and the refrigerant flows to the second flow path 6b side (the liquid refrigerant cooling line 41 side), in the liquid refrigerant cooling line 41 The refrigerant whose pressure is reduced in pressure and whose temperature is lowered by the flow rate control valve 11 exchanges heat with the liquid refrigerant flowing through the first flow path 6a, and the liquid refrigerant flowing through the first flow path 6a is further supercooled. The liquid refrigerant that has flowed out of the first flow path 6a is decompressed by the pressure reducing mechanism 7 of the low pressure machine III, and becomes a gas-liquid mixed refrigerant. The gas-liquid mixed refrigerant absorbs heat from the surrounding object to be cooled (cools the object to be cooled) and evaporates, and becomes a low-temperature, low-pressure gas refrigerant, and is again sucked into the compressor 1.

Here, a Mollier diagram of the refrigeration cycle in a state where the liquid injection line 42 does not have the refrigerant flowing and a state in which the refrigerant flows may be described with reference to FIG. 2 . In FIG. 2, the Mollier diagram in a state where the liquid refrigerant cooling line 41 does not have a refrigerant flowing is indicated by a solid line 61, and the liquid refrigerant cooling pipe is used. The Mollier diagram of the road 41 in a state in which the refrigerant flows is indicated by a broken line 62.

Next, the basic operation of the liquid refrigerant cooling line 41 will be described with reference to Figs. 1 and 2 .

When the cooling load of the low-pressure machine III fluctuates, the suction pressure of the compressor 1 fluctuates. Therefore, the pressure fluctuation is detected by the suction pressure sensor 14, and the detected suction pressure value is input to the controller 16. The controller 16 controls the flow rate control valve 11 of the liquid refrigerant cooling line 41 in response to the detected suction pressure value, and adjusts the freezing capacity to correspond to the cooling temperature (set temperature) of the low pressure machine III to become the determined suction pressure value.

For example, when the suction pressure value detected by the suction pressure sensor 14 is greater than the set suction pressure value, the controller 16 causes the flow control valve 11 of the liquid refrigerant cooling line 41 to increase. The direction of the opening is large. In this way, a part of the liquid refrigerant that has been supercooled in the air-cooling heat exchanger 3 and flows through the main line is branched to the second flow path 6b side and flows to the liquid refrigerant cooling pipe 41 side. The liquid refrigerant is decompressed in the flow rate control valve 11 of the liquid refrigerant cooling line 41, exchanges heat with the liquid refrigerant flowing through the main path of the first flow path 6a, and absorbs heat, and flows through the first flow. The liquid refrigerant of the passage 6a is further supercooled and evaporates by itself, and then injected into the injection port provided at the intermediate pressure portion of the compressor 1.

In this manner, the liquid refrigerant flowing through the main pipe is further cooled and flows to the low-pressure machine III side, so that the cooling capacity is increased, and the temperature of the low-pressure machine III can be lowered. Therefore, in the aforementioned suction pressure sensor 14 The measured suction pressure value will also decrease, and it will gradually approach the set suction pressure value. In the present embodiment, since the liquid temperature sensor 18 is provided, if the controller 16 further extracts the temperature of the liquid refrigerant obtained from the liquid temperature sensor 18, the opening degree of the flow rate control valve 11 is controlled. The aforementioned flow control valve 11 can be controlled to an appropriate opening degree more quickly.

The role of this will be explained in detail using the Mollier diagram shown in Fig. 2. In Fig. 2, when the flow rate control valve 11 of the liquid refrigerant cooling line 41 is closed, it will operate like a freezing device in which the liquid refrigerant cooling line 41 is not normally provided, so that the Mollier line diagram will become The line shown by line 61 has an Enthalpy Change indicated by Δq1. On the other hand, when the flow rate control valve 11 of the liquid refrigerant cooling line 41 is opened, the liquid refrigerant cooling line 41 operates, and the Mollier diagram of the main line is as shown by the broken line 62 in FIG. The line diagram expands toward the low side, which makes it larger as shown by Δq2.

As can be seen from FIG. 2, the liquid refrigerant cooling line 41 is operated to adjust the degree of subcooling of the liquid refrigerant flowing through the main line as shown in the adjustment range A, whereby the refrigeration capacity of the refrigerator unit II can be improved. Poor) increases. That is, the freezing capacity is expressed by the multiplication value of the refrigerant circulation amount and the enthalpy difference, and if the circulation amount of the refrigerant flowing through the low-pressure machine III is the same, the enthalpy difference Δq1 is compared with the state in which the liquid refrigerant cooling line 41 is not operated. When the liquid refrigerant cooling pipe 41 is in operation, the enthalpy difference Δq2 is large, so that the refrigeration capacity is increased.

The controller 16 is configured to respond to the suction pressure value detected by the suction pressure sensor 14 (in other words, in response to the load of the refrigeration device) The change) controls the opening degree of the flow rate control valve 11 of the liquid refrigerant cooling line 41. By controlling the opening degree of the flow rate control valve 11 of the liquid refrigerant cooling line 41, the refrigerant flowing through the liquid refrigerant cooling line 41 is depressurized and the amount of refrigerant is changed, whereby the refrigeration capacity of the refrigerator unit II can be changed. .

In other words, if the opening degree of the flow rate control valve 11 of the liquid refrigerant cooling line 41 is increased, the amount of refrigerant flowing through the liquid refrigerant cooling line 41 can be increased to flow to the main line (1st) The amount of subcooling of the liquid refrigerant in the side of the flow path 6a is increased, and the refrigeration capacity can be increased. On the other hand, if the opening degree of the flow rate control valve 11 of the liquid refrigerant cooling line 41 is controlled to be reduced, the amount of refrigerant flowing through the liquid refrigerant cooling line 41 can be reduced, and the liquid refrigerant flowing through the main line can be passed. The amount of cooling will be reduced, so the refrigeration capacity can be reduced.

As described above, by operating the liquid refrigerant cooling line 41, as shown by the broken line 62 of the Mollier diagram of Fig. 2, the degree of subcooling of the liquid refrigerant can be increased to increase the refrigeration capacity, and the low temperature refrigerant can be injected. Since the intermediate pressure portion of the compressor 1 can also lower the temperature at which the refrigerant gas discharged from the compressor 1 is discharged.

That is, by controlling the flow rate control valve 11 of the liquid refrigerant cooling line 41, the degree of subcooling of the liquid refrigerant supplied to the low pressure machine III can be varied, so that the refrigeration capacity can be controlled without changing the refrigerant circulation to the low pressure machine III side. The amount and the amount of oil return to the compressor 1 described above can be prevented from being reduced even if the cooling load of the low-pressure machine III is small.

Next, the basic operation of the liquid injection line 42 will be described with reference to FIG. In this embodiment, the discharge gas temperature sensor 15 is provided. According to the detected temperature value of the discharge gas temperature sensor 15, the controller 16 controls the setting. The pressure reducing means of the liquid injection line 42 (in the case of using an electronic expansion valve, it is also a flow control means) 9. When the decompression means 9 is turned on, a part of the liquid refrigerant that has flowed from the air subcooling heat exchanger 5 and flows through the main line is branched to the liquid injection line 42. The liquid refrigerant that has flowed through the liquid injection line 42 is decompressed by the decompression means 9, and then injected into the injection port provided in the intermediate pressure portion of the compressor 1.

The decompression means 9 is controlled by the controller 16 to be turned on when the detected temperature value of the discharge gas temperature sensor 15 is equal to or higher than the set temperature, and when the detected temperature value is lower than the set temperature, Closed under control. As described above, by operating the liquid injection line 42, the compressor 1 can be cooled and the temperature thereof can be prevented from rising, so that the reliability can be improved.

Next, the control based on the aforementioned suction pressure sensor 14 and the change in the refrigeration capacity caused by the control will be described with reference to FIGS. 3 and 4. Fig. 3 is a flow chart for explaining the control operation of the refrigeration system 1 shown in Fig. 1, and Fig. 4 is an explanatory line diagram showing an example of a change in the refrigeration capacity based on the control operation of Fig. 3.

In Fig. 3, 16 is the controller shown in Fig. 1, and the operation in the controller 16 is illustrated by the flowchart of Fig. 3. In the controller 16, the detected pressure value Ps from the suction pressure sensor 14 shown in Fig. 1 is taken at any time as the cooling load variation of the low pressure machine III (step S1). On the other hand, a set suction pressure value range (hereinafter also referred to as a set pressure range) corresponding to the cooling temperature (set temperature) of the low-pressure machine III is set (step S2).

The aforementioned suction pressure sensing when a load change occurs in the low pressure machine III The detected pressure value Ps of the device 14 fluctuates, so that the detected pressure value Ps is compared with the aforementioned set pressure range (step S3).

From the comparison result, it is determined whether or not the detected pressure value Ps is higher than the set pressure range. When it is determined that the detected pressure value Ps is higher than the set pressure range, it is considered that it is necessary to increase the freezing capacity, so the process moves to the next step. At S4, it is first determined whether or not the refrigerant circulation amount is the maximum (Max) (step S4). Whether the amount of refrigerant circulation is the maximum can be determined by whether the number of revolutions of the compressor is the largest.

In the step S4, when it is determined that the refrigerant circulation amount is not the maximum, it is determined whether or not the opening degree (the flow rate of the liquid refrigerant cooling line) of the flow rate control valve 11 of the liquid refrigerant cooling line 41 is the maximum (step S5). When it is determined in step S5 that the opening degree of the flow rate control valve 11 of the liquid refrigerant cooling line 41 is not the maximum, the process proceeds to step S6, and the opening degree of the flow rate control valve (electronic expansion valve) 11 is increased (UP). This increases the refrigeration capacity of the freezer unit II (UP).

By the control of the flow rate control valve 11 in this step S6, as shown in FIG. 4, the refrigeration capacity of the refrigerator unit II can be adjusted within the range of the refrigeration capacity control area B of the liquid refrigerant cooling line 41 indicated by hatching. . For example, when the refrigerant circulation amount shown in Fig. 4 is 50%, the refrigeration capacity can be adjusted within a range of 40% (flow control valve 11 fully closed state) to 50% (flow control valve 11 fully open state).

In the above step S5, when it is determined that the opening degree of the flow rate control valve 11 of the liquid refrigerant cooling line 41 is the maximum, the process proceeds to step S7 of Fig. 3, the number of revolutions of the compressor 1 is increased (the operation volume is increased), and the refrigerant is circulated. Increase in quantity (UP), thereby increasing the refrigeration capacity (UP). That is, the number of revolutions of the compressor 1 is increased in accordance with the detected pressure value Ps of the suction pressure sensor 14, and the compressor 1 is controlled by the inverter to increase the circulation amount of the refrigerant. By the number of revolutions control (volume control) of the compressor 1, as shown by the solid line 63 in FIG. 4, the refrigerant circulation amount is controlled within the range of 50% to 100%, whereby the refrigeration capacity can be adjusted to 40%. ~80% range.

In the above step S4, when it is determined that the refrigerant circulation amount is the maximum, the refrigeration capacity cannot be expected to be increased by the compressor operation volume control. Therefore, the process proceeds to step S8, and it is determined whether or not the flow rate of the liquid refrigerant cooling line 41 is the maximum (Max). ). The flow rate of the liquid refrigerant cooling line 41 is the amount of refrigerant flowing through the second flow path 6b of the supercooling heat exchanger 6, and the amount of the refrigerant is the opening degree of the flow rate control valve 11 of the liquid refrigerant cooling line 41. Determined. Therefore, by determining whether or not the flow rate control valve 11 of the liquid refrigerant cooling line 41 is at the maximum opening degree, it is possible to determine whether or not the liquid refrigerant cooling line flow rate is maximum.

When it is determined in step S8 that the flow rate of the liquid refrigerant cooling line 41 is not the maximum, the process proceeds to step S9, and the opening degree of the flow rate control valve (electronic expansion valve) 11 of the liquid refrigerant cooling line 41 is increased (UP). The flow rate of the liquid refrigerant cooling line 41 is increased to increase the refrigeration capacity (UP). By the flow rate control of the liquid refrigerant cooling line 41, as shown in the refrigeration capacity control area B of the liquid refrigerant cooling line 41 in Fig. 4, the refrigeration capacity can be adjusted in a state where the refrigerant circulation amount is 100%. 80%~100% range.

In the above step S8, when it is determined that the flow rate of the liquid refrigerant cooling line 41 is the maximum, the freezing capacity is maximized, so that the operating state is maintained. (Step S10).

In the foregoing step S3, when the detected pressure value Ps is not higher than the set pressure range, the process proceeds to step S11, and it is determined whether or not the detected pressure value Ps is lower than the set pressure range. In step S11, when it is determined that the detected pressure value Ps is lower than the set pressure range, it is necessary to reduce the freezing capacity. Therefore, the process proceeds to step S12, and it is first determined whether or not the flow rate of the liquid refrigerant cooling line 41 is the minimum (Min). In the determination, when it is determined that the flow rate of the liquid refrigerant cooling line 41 is not the minimum, the process proceeds to step S13, and the opening of the flow rate control valve (electronic expansion valve) 11 is controlled in accordance with the detected pressure value Ps ( Down), the amount of liquid refrigerant circulating in the liquid refrigerant cooling line 41 is reduced. As a result, the degree of subcooling of the liquid refrigerant flowing through the main pipe can be reduced, and the refrigeration capacity can be reduced (Down), and the suction pressure value of the compressor 1 can be increased to enter the set pressure range.

In the above step S12, when it is determined that the flow rate of the liquid refrigerant cooling line 41 is the smallest (the opening degree of the flow rate control valve 11 is the smallest), the process proceeds to the next step S14, and the inverter is controlled by the inverter according to the detected pressure value Ps. The compressor 1 reduces the number of revolutions (volume) of the compressor 1 to reduce the amount of refrigerant circulation. As a result, the circulation amount of the refrigerant circulating through the main pipe is reduced, so that the refrigeration capacity can be controlled to reduce the suction pressure value of the compressor 1 and enter the set pressure range.

In the above step S11, when it is determined that the detected pressure value Ps is not lower than the set pressure range, it can be determined that the detected pressure value Ps is within the set pressure range, so that the operating state is maintained (step S15).

The conventional liquid refrigerant cooling line 41 is not provided in the conventional freezing apparatus, and When the supercooling heat exchanger 6 is supercooled, as shown by the solid line 63 in Fig. 4, the characteristic of the "no subcooling degree control" is 50% when the volume control of the compressor 1 is controlled for the refrigerant circulation amount. At 100%, the control range for freezing capacity is 40% to 80%.

On the other hand, according to the refrigeration apparatus of the present embodiment described above, the liquid refrigerant cooling line 41 is provided, and the degree of subcooling in the supercooling heat exchanger 6 can be controlled by controlling the amount of liquid refrigerant passing therethrough. . Therefore, even if the volume control of the compressor 1 is 50% to 100% as the above-described conventional control range of the refrigerant circulation amount, the control range of the refrigeration capacity can be changed except for the characteristic shown by the solid line 63 in Fig. 4. Further, it is increased to the characteristic range of "overcooling control" shown by the broken line 64, so it can be greatly expanded to 40% to 100%. As a result, the object to be cooled such as the food cooled by the low-pressure machine III can be accurately cooled, so that the cooling can be prevented from being insufficient, and the freshness can be maintained, and excessive cooling can be prevented.

Further, according to the present embodiment, the amount of the liquid refrigerant that is circulated to the liquid refrigerant cooling line 41 is preferentially controlled in comparison with the suction capacity based on the suction pressure of the compressor, so that the number of revolutions (volume) of the compressor can be further reduced. Come to work. As a result, the reliability of the compressor can be improved, energy can be saved, and the COP of the refrigeration system can be improved.

That is, the refrigeration capacity control of the liquid refrigerant cooling line 41 can be used at any evaporation temperature of the low pressure machine III, so that the variable range of the refrigeration capacity can be maximized, by reducing the compressor as much as possible. The number of revolutions can be operated to improve the COP.

Also, due to the low temperature refrigerant gas from the liquid refrigerant cooling line 41 Since it is injected into the intermediate pressure portion of the compressor, the compressor can be cooled, and the temperature rise can be suppressed.

As described above, according to the present embodiment, the refrigeration capacity can be increased at the same refrigerant circulation amount, so that the number of revolutions (volume) of the compressor can be further reduced, and stable operation with less fluctuation in the number of revolutions can be achieved. As a result, the effect is that a refrigeration apparatus capable of improving the reliability of the compressor and achieving energy saving can be obtained.

In other words, in the present embodiment, it is possible to obtain an effect that the fluctuation of the operating volume of the compression device (compressor) can be reduced and stabilized, and the necessary refrigeration capacity can be obtained even if the load of the refrigeration cycle fluctuates. The burden on the compression device is reduced, the reliability is improved, and the drive current of the compression device can be suppressed from increasing to save energy.

1‧‧‧Compressor (compression device)

2‧‧‧ oil separator

3‧‧‧Condenser

4‧‧‧Acceptor

5‧‧‧Air overcooling heat exchanger

6‧‧‧Overcooling heat exchanger

6a‧‧‧1st runner

6b‧‧‧2nd runner

7‧‧‧Relief mechanism

8‧‧‧Evaporator

9,10‧‧‧Decompression

11‧‧‧Flow control valve (flow control means)

14‧‧‧Inhalation pressure sensor

15‧‧‧Spit gas temperature sensor

16‧‧‧ Controller

17‧‧‧Return line

18‧‧‧Liquid temperature sensor

19‧‧‧Spit pressure sensor

41‧‧‧Liquid refrigerant cooling line

42‧‧‧Liquid injection line

60‧‧‧Cooling fan

I‧‧‧freezer

II‧‧‧Freezer unit

III‧‧‧Low-voltage machine

A‧‧‧Adjustment range of subcooling

B‧‧‧Frozen capacity control area for liquid refrigerant cooling line

Fig. 1 is a schematic view showing the structure of a refrigeration cycle of the refrigeration system of the present invention.

[Fig. 2] The Mollier Diagram of the refrigeration apparatus of Fig. 1.

Fig. 3 is a flow chart showing the control operation of the freezing apparatus 1 shown in Fig. 1.

Fig. 4 is an explanatory line diagram showing an example of a change in the freezing ability based on the control operation of Fig. 3.

1‧‧‧Compressor (compression device)

2‧‧‧ oil separator

3‧‧‧Condenser

4‧‧‧Acceptor

5‧‧‧Air overcooling heat exchanger

6‧‧‧Overcooling heat exchanger

6a‧‧‧1st runner

6b‧‧‧2nd runner

7‧‧‧Relief mechanism

8‧‧‧Evaporator

9,10‧‧‧Decompression

11‧‧‧Flow control valve (flow control means)

14‧‧‧Inhalation pressure sensor

15‧‧‧Spit gas temperature sensor

16‧‧‧ Controller

17‧‧‧Return line

18‧‧‧Liquid temperature sensor

19‧‧‧Spit pressure sensor

41‧‧‧Liquid refrigerant cooling line

42‧‧‧Liquid injection line

60‧‧‧Cooling fan

I‧‧‧freezer

II‧‧‧Freezer unit

III‧‧‧Low-voltage machine

Claims (11)

A refrigerating apparatus comprising a refrigerating cycle, wherein the refrigerating cycle is configured by sequentially connecting a refrigerant pipe to: a compression device capable of controlling a volume; and a condenser for coagulating a high-pressure refrigerant compressed by the compression device; and a pressure reducing mechanism Depressurizing the high-pressure refrigerant condensed in the condenser; and an evaporator to evaporate the low-pressure refrigerant decompressing the pressure-reducing mechanism; the refrigeration device having a liquid-coolant cooling line, as described above a part of the high-pressure liquid refrigerant in the main circulation of the refrigeration cycle is taken out and depressurized to form a reduced-pressure refrigerant, and the liquid refrigerant flowing through the main line is supercooled, and the liquid refrigerant after the main line is cooled is reduced. The pressure refrigerant is injected into the intermediate pressure portion of the compressor; the flow rate control means is for controlling the flow rate of the liquid refrigerant flowing through the liquid refrigerant cooling line and depressurizing; and the controller controls the flow rate according to the load fluctuation of the main line Control means; the controller is required to increase the refrigeration capacity in response to a load change of the main line, or to reduce the refrigeration capacity After the under either case, the flow control system to control the refrigeration capacity the control means, if necessary also in the case where the compression volume control means to control the refrigeration capacity of the Department of capacity control for the compressor. The refrigerating device of claim 1, wherein the compressible device of the controllable volume has at least one compressor capable of controlling the number of revolutions. Such as the freezing device of claim 2, wherein a suction pressure sensor that detects a suction pressure of the compression device to detect a load change of the main line; the controller controls the flow control device according to a suction pressure value detected by the suction pressure sensor After controlling the freezing capacity, if it is necessary to control the freezing capacity by the volume control of the above-described compression device, the number of revolutions of the compressor that can control the number of revolutions is controlled. The refrigeration system according to claim 3, wherein the main pipe between the condenser and the pressure reducing mechanism is provided with a supercooling heat exchanger, and is configured to flow through the liquid refrigerant cooling pipe The liquid refrigerant flowing through the main passage of the supercooling heat exchanger is supercooled by the decompressed refrigerant. The refrigeration system of claim 1, wherein the flow rate control means is an electronic expansion valve. The refrigeration system according to the first aspect of the invention, further comprising a liquid injection line for extracting a part of the high-pressure liquid refrigerant circulating in the main line of the refrigeration cycle and decompressing the pressure-reduced refrigerant The medium pressure portion of the compressor is injected; and the pressure reducing means provided in the liquid injection line is controlled in accordance with the temperature of the discharge gas discharged from the compressor 1 or the degree of superheat of the discharge gas. A refrigeration system according to claim 4, wherein a liquid temperature sensor is provided on an outlet side of the supercooling heat exchanger, and the controller is configured to extract a liquid temperature sensor. The liquid refrigerant temperature controls the opening of the flow control means. A refrigeration device according to claim 1, wherein the foregoing The controllable volume compression device is one of which is a combination of a plurality of fixed-volume type compressors and a control unit for controlling the volume by means of the number control; or a variable displacement compressor The fixed volume compressor combination is used to make a compression device with a controllable volume. The refrigerating apparatus of claim 4, wherein the liquid receiver is disposed downstream of the condenser, and the air subcooling heat exchanger is provided, and the liquid refrigerant from the liquid receiver is further supercooled by outside air; The subcooling heat exchanger is provided on the downstream side of the air subcooling heat exchanger. The refrigeration system of claim 1, wherein an oil separator is disposed between the compression device and the condenser, and a return line is provided for returning oil in the oil separator to the compression device. On the suction side, a pressure reducing means is provided in the oil return line. A chiller unit comprising: a compression device for controlling a volume; and a condenser for condensing a high-pressure refrigerant compressed by the compression device; and a low-pressure machine for constituting a refrigeration cycle, the low-pressure machine having a pressure-reducing mechanism Decompressing the high-pressure refrigerant condensed in the condenser; and evaporating the low-pressure refrigerant decompressing the pressure-reducing mechanism; the refrigerator unit is characterized in that: a liquid refrigerant cooling pipe is provided by A refrigerant gas obtained by extracting a part of the high-pressure liquid refrigerant from the refrigerant pipe of the main line of the refrigeration cycle and depressurizing the refrigerant, and supercooling the liquid refrigerant flowing through the main pipe, and cooling the liquid refrigerant of the main pipe The aforementioned reduced pressure refrigerant is injected into the intermediate pressure portion of the compressor; a flow control means for controlling a flow rate of the liquid refrigerant flowing through the liquid refrigerant cooling line and pre-decompressing; and a controller for detecting a load change of the main line to control the flow control means; the controller, in response to the foregoing In any case where the load of the main line has to be increased and the refrigeration capacity must be increased or the refrigeration capacity must be reduced, the volume control means is controlled to control the refrigeration capacity, and the volume of the compression device is required. In the case of controlling the control of the freezing capacity, the volume control of the compressor is performed.