JP2008082678A - Supercooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep refrigeration power even when a device is replaced by a refrigerating device for HFC refrigerant in existing indoor equipment and indoor piping designed for a HCFC refrigerant, and to prevent degradation of operation efficiency caused by increase of pressure loss by preventing increase of a flow rate of the refrigerant. <P>SOLUTION: Indoor piping connecting a refrigerating device of a main refrigerating cycle and indoor equipment is routed through a supercooling device of a sub-refrigerating cycle, so that a condenser of the sub-refrigerating cycle can be installed outdoors as a condensing unit independently from the supercooling device. Thus the sub-refrigerating cycle can be installed without extending a piping length of the indoor piping of the main refrigerating cycle. Loss of cold and pressure loss generated during the circulation of liquid refrigerant in refrigerant piping can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigeration apparatus for use in a refrigeration apparatus that is used by being connected to indoor equipment such as a showcase or an air conditioner via an indoor pipe, and further intended to supercool the liquefied refrigerant.

  At present, refrigeration devices using HCFC refrigerants such as R22 are widely used in convenience stores (CVS) and large mass retailers. These refrigeration apparatuses include a separation type in which a condenser is separately installed as shown in FIG. 1 or an integral type in which the condenser is integrated with the refrigeration apparatus. However, the HCFC refrigerants used in these refrigeration devices are regulated because they have the property of destroying the ozone layer.

Therefore, it is considered that the number of refrigeration apparatuses using HFC refrigerants such as R32, R407A, and R410A that do not destroy the ozone layer will increase in the future. In addition, since the regulation of HCFC refrigerant is performed in stages, it is considered that replacement of existing facilities using HCFC refrigerant with HFC refrigerant will proceed (see Patent Document 1).
JP 2001-201215 A

  However, since the HFC refrigerant has physical properties different from those of the HCFC refrigerant, the refrigeration apparatus using the HCFC refrigerant cannot be directly used as the HFC refrigerant refrigeration apparatus. Therefore, when the HFC refrigerant is used in the HCFC refrigerant refrigeration apparatus, it is necessary to cope with the physical properties thereof.

  For example, since the HFC refrigerant has a higher operating pressure at the same evaporation temperature than the HCFC refrigerant, it is necessary to pay attention to the pressure resistance performance of piping and the like. Furthermore, since the refrigeration capacity per unit volume of the HFC refrigerant is lower than that of the HCFC refrigerant, it is necessary to increase the refrigerant flow rate to obtain the same level of refrigeration capacity as the HCFC refrigerant.

  Therefore, when an existing indoor pipe designed for an HCFC refrigerant refrigeration system is used at a CVS or a large mass retailer and replaced with an HFC refrigerant refrigeration system, when the HCFC refrigerant is used In order to ensure the same level of refrigeration capacity, it is necessary to increase the flow rate of the refrigerant by increasing the flow rate of the refrigerant. However, when the flow rate of the refrigerant increases, the pressure loss in the indoor piping increases, so the energy loss when the refrigerant circulates increases and the operating efficiency decreases.

  In order to maintain the refrigeration capacity without increasing the flow rate of the refrigerant, there is a method to increase the refrigerant flow rate by increasing the inner diameter of the indoor piping and increasing the cross-sectional area, but laying the indoor piping in the existing indoor equipment To start over, very expensive costs and time are required.

  Therefore, the present invention maintains the refrigeration capacity and suppresses the increase in the flow rate of the refrigerant in the existing indoor equipment and indoor piping designed for the HCFC refrigerant even when the refrigerant is replaced with a refrigeration apparatus for the HFC refrigerant. The purpose is to prevent a decrease in operating efficiency due to an increase in pressure loss.

  Note that the present invention is not limited to the case of using existing indoor equipment and indoor piping, and when a new refrigeration apparatus using an HFC refrigerant is developed, the size of the refrigeration apparatus using an HCFC refrigerant is approximately the same. The necessary refrigeration capacity can be ensured by the refrigeration apparatus.

  The present invention has been made in view of the above problems, and the invention according to claim 1 is a main refrigeration comprising a refrigeration apparatus having a compressor and a condenser, and an indoor facility having a decompression apparatus and an evaporator. In the cycle, a sub-refrigeration cycle including a subcooling heat exchanger that supercools the refrigerant flowing out of the condenser is provided between the condenser and the decompression device. It comprises a device, a supercooling device comprising the supercooling heat exchanger, and a condensing unit comprising a condenser.

  According to a second aspect of the present invention, in the refrigeration system according to the first aspect, the condensing unit is installed outdoors.

  According to a third aspect of the present invention, in the refrigeration system according to the first and second aspects of the present invention, an indoor pipe that connects the indoor equipment is provided, and the indoor pipe is designed to meet the specifications of the HCFC refrigerant, and the main refrigeration system The refrigerant used in the cycle and the sub-refrigeration cycle is an HFC refrigerant.

    According to a fourth aspect of the present invention, in the refrigeration system according to the first to third aspects, the evaporation temperature of the main refrigeration cycle is lower than the evaporation temperature of the sub refrigeration cycle.

  According to a fifth aspect of the present invention, in the refrigeration system according to the first to fourth aspects, the condenser of the main refrigeration system is provided separately from the refrigeration apparatus.

  According to the present invention, the indoor piping connecting the refrigeration apparatus of the main refrigeration cycle and the indoor equipment can be routed through the subcooling apparatus of the sub refrigeration cycle, and the condensing unit of the sub refrigeration cycle can be installed outdoors. Since the condenser of the sub refrigeration cycle can be installed outdoors as a condensing unit independently of the supercooling device, the supercooling device can be arranged at any position on the indoor piping of the main refrigeration cycle. Therefore, since the auxiliary refrigeration cycle can be arranged without extending the length of the indoor piping of the main refrigeration cycle, it is possible to reduce the loss of cooling heat and the loss of pressure generated while the liquid refrigerant flows through the refrigerant piping. it can.

  Hereinafter, the implementation method of this invention is demonstrated in detail using drawing.

  FIG. 2 is a refrigerant circuit diagram of a refrigeration apparatus to which the present invention is applied, and includes a refrigeration apparatus 1, a condensing unit 2, and a supercooling unit 3 (sub-refrigeration cycle). The gaseous refrigerant flowing from the refrigerant inlet A of the refrigeration apparatus 1 becomes liquid refrigerant and flows from the refrigerant outlet B to the refrigerant inlet C of the supercooling unit 3, and the supercooled liquid refrigerant flows from the refrigerant outlet D to the showcase or air conditioning. It flows out to indoor piping (not shown) equipped with a machine.

  The indoor piping is already laid in CVS or a large mass retailer, and the piping with the piping diameter designed for the HCFC refrigerant is used as it is. In the present invention, the indoor pipe is not limited to the existing pipe, but can be applied to a pipe newly installed together with the refrigeration apparatus, and the pipe diameter is not limited to that designed for the HCFC refrigerant.

  In this embodiment, an indoor unit is assumed indoors as the refrigeration apparatus 1, and a condenser that performs heat exchange is separated from the refrigeration apparatus 1 as a condensing unit 2 and provided outdoors. The present invention is not limited to this, and can be applied to an integrated refrigeration apparatus in which a condenser is integrated with a refrigeration apparatus.

  Moreover, although R407A is assumed as a refrigerant of the refrigeration apparatus 1, it is not limited to this, and any refrigerant that can be set lower than the evaporation temperature of the sub-refrigeration cycle is applicable.

  The configuration of the refrigeration apparatus 1 and the refrigerant flow will be described. Contaminants are removed from the gaseous refrigerant flowing in from the refrigerant inlet A by the strainer 104 and separated into liquid refrigerant and gaseous refrigerant by the accumulator 105. The liquid refrigerant is stored in the accumulator 105, and only the gas refrigerant is sucked by the compressors 100 and 101 and is discharged after being compressed to high temperature and high pressure.

  In this embodiment, the compressor 100 uses a variable speed compressor with a variable operating frequency, and the compressor 101 uses a constant speed compressor with a constant operating frequency. However, both the compressor 100 and the compressor 101 have operating frequencies. A constant constant speed compressor may be used.

  The gaseous refrigerant compressed to high temperature and high pressure by the compressors 100 and 101 is discharged while containing the lubricating oil in the compressor. The discharged gas refrigerant flows into the oil separator 102 and the oil component is separated, and then flows into the condenser 200 disposed in the condensing unit 2.

  The lubricating oil separated in the oil separator 102 is returned to the compressors 100 and 101 via the electromagnetic valves 107 and 108 after the contaminants are removed in the strainer 106. At this time, the opening and closing of the electromagnetic valves 107 and 108 are controlled so that the lubricating oil in the compressor becomes a certain value or more for each compressor.

  The liquid refrigerant cooled and condensed in the condenser 200 returns to the refrigeration apparatus 1 from the condensing unit 2 and is stored in the liquid receiver 103. The liquid refrigerant stored in the liquid receiver 103 flows from the refrigerant outlet B of the refrigeration apparatus 1 to the refrigerant inlet C of the supercooling unit 3 and is supercooled in the heat exchanger 305 and then from the refrigerant outlet D of the supercooling unit 3. It flows out to indoor equipment such as a showcase and an air conditioner through indoor piping.

  In addition, a liquid injection circuit is provided to prevent the compressors 100 and 101 from becoming high temperature. In the liquid injection circuit, the liquid refrigerant drawn from the liquid receiver 103 is removed from the contaminants in the strainers 109 and 112, and then passed through the expansion valves 110 and 113 and the electromagnetic valves 111 and 114 in order to the compressors 100 and 101. Supplied to cool each compressor. The degree of opening and closing of the expansion valves 110 and 113 and the opening and closing of the electromagnetic valves 111 and 114 are controlled so that the temperature of the refrigerant discharged from the compressors 100 and 101 is within a certain range.

  The operation control method of the refrigeration apparatus 1 will be described. Note that the operation control method of the refrigeration apparatus 1 is not limited to the method shown in this embodiment, and any conventional operation control method may be used. In any operation control method, the effect of the present invention by the supercooling unit 3 can be obtained. it can.

  The suction side pressure (low pressure) of the compressor of the refrigeration apparatus 1 is measured by a pressure sensor (not shown), and the low pressure pressure is compared with a predetermined pressure I and a predetermined pressure II to control the operation. Made. The predetermined pressure II is larger than the predetermined pressure I.

  When the low pressure is smaller than the predetermined pressure I, both the compressor 100 and the compressor 101 are stopped. When the low-pressure pressure becomes equal to or higher than the predetermined pressure I, the variable speed compressor 100 starts at the minimum operating frequency, and when the low-pressure pressure is within the range of the predetermined pressure I and lower than the predetermined pressure II, the low-pressure pressure increases. The operating frequency increases. When the low pressure becomes equal to or higher than the predetermined pressure II, the variable speed compressor 100 operates again at the minimum operating frequency, and the constant speed compressor 101 starts. Thereafter, the constant speed compressor 101 continues to operate, and the operating frequency of the variable speed compressor 100 increases as the low pressure increases.

  Further, when the low pressure decreases and becomes equal to or lower than the predetermined pressure II, the constant speed compressor 101 stops and the variable speed compressor 100 operates at the maximum operating frequency. Thereafter, the operating frequency of the variable speed compressor 100 decreases as the low pressure decreases until the low pressure reaches the predetermined pressure I. When the low pressure becomes the predetermined pressure I or less, the variable speed compressor 100 stops. .

  The configuration of the supercooling unit 3 and the refrigerant flow will be described. The supercooling unit 3 constitutes a sub refrigeration cycle independent of the main refrigeration cycle including the refrigeration apparatus 1, the condensing unit 2, the indoor piping, and the indoor equipment, and the main refrigeration cycle and the sub refrigeration cycle are thermally coupled. ing.

  Although R410A is assumed as the refrigerant of the supercooling unit 3, the present invention is not limited to this, and any refrigerant can be used as long as the evaporation temperature is set higher than the evaporation temperature of the main refrigeration cycle. .

  In the supercooling unit 3, the refrigerant compressed and discharged by the compressor 300 flows into the oil separator 301. Since the discharged refrigerant contains lubricating oil in the compressor, the lubricating oil is removed in the oil separator 301 and then flows into the condenser 302. The temperature and pressure of the discharged refrigerant are measured by the temperature sensor 312 and the pressure sensor 313.

  In this embodiment, a variable speed compressor having a variable operation frequency is used as the compressor 300, but a constant speed compressor having a constant operation frequency may be used.

  The lubricating oil separated in the oil separator 301 is returned to the compressor 300 via the electromagnetic valve 308 after contaminants are removed in the strainer 307. Since the supercooling unit 3 is a closed refrigeration cycle, there is little lubricating oil remaining in the refrigeration circuit. Further, since only one compressor is mounted, the amount of lubricating oil returning to the compressor 300 may not be adjusted by the electromagnetic valve 308.

  The refrigerant cooled and condensed in the condenser 302 to become a liquid is stored in the liquid receiver 303. A part of the liquid refrigerant stored in the liquid receiver 303 is used for liquid injection for keeping the temperature of the compressor 300 in a certain range.

  In the liquid injection circuit, the refrigerant drawn from the liquid receiver 303 flows into the compressor 300 via the expansion valve 310 and the electromagnetic valve 311 after the contaminants are removed by the strainer 309, and cools the compressor 300. The opening degree of the expansion valve 310 and the opening and closing of the electromagnetic valve 311 are controlled so that the temperature of the refrigerant discharged from the compressor 300 is within a certain range.

  The liquid refrigerant stored in the liquid receiver 303 is depressurized by the expansion valve 304, flows into the sub refrigeration cycle side of the cascade heat exchanger 305 (supercooling heat exchanger), and evaporates, whereby the cascade heat exchanger 305 Cool (supercool) the high-temperature liquid refrigerant flowing through the main refrigeration cycle. In addition, the refrigerant temperature at the sub refrigeration cycle side inlet of the cascade heat exchanger 305 is measured by the temperature sensor 314, and the refrigerant temperature at the main refrigeration cycle side inlet is measured by the temperature sensor 317.

  Since the refrigerant that has flowed out from the sub-refrigeration cycle side outlet of the cascade heat exchanger 305 partially includes liquid refrigerant, the accumulator 306 separates the refrigerant into liquid refrigerant and gas refrigerant. The liquid refrigerant is stored in the accumulator 306, and only the gas refrigerant is sucked into the compressor 300. Further, the refrigerant flowing out from the main refrigeration cycle side outlet of the cascade heat exchanger 305 flows out from the refrigerant outlet D of the supercooling unit 3 to indoor facilities such as a showcase and an air conditioner through indoor piping.

  The refrigerant temperature at the sub-refrigeration cycle side outlet of the cascade heat exchanger 305 is measured by the temperature sensor 315, the refrigerant temperature at the main refrigeration cycle side outlet is measured by the temperature sensor 318, and the refrigerant pressure at the main refrigeration cycle side outlet is the pressure. Measured by the sensor 319, the low pressure side pressure of the compressor 300 is measured by the pressure sensor 316.

  In the present embodiment, since the condenser 302 is integrated as a configuration of the supercooling unit 3, an outdoor unit is assumed which is disposed outdoors and capable of exchanging heat with the outside air. However, the present invention is not limited to this, and the condenser may be separately provided as a condensing unit, and the supercooling unit 3 may be an indoor unit provided indoors.

  Further, as shown in FIG. 3, by providing the internal heat exchanger 320, it is possible to exchange heat between the liquid refrigerant before being supercooled in the cascade heat exchanger 305 and the supercooled liquid refrigerant. Become. Thereby, since the temperature difference of the liquid refrigerant between the inlets and outlets on the main refrigeration cycle side of the cascade heat exchanger 305 can be reduced, the life of the cascade heat exchanger 305 can be extended.

  The operation control method of the supercooling unit 3 will be described.

(1) Supercooling degree constant operation mode In the supercooling unit 3, the refrigerant pressure at the outlet of the main refrigeration cycle side of the cascade heat exchanger 305 is measured by the pressure sensor 319, and the refrigerant saturation temperature (refrigerant saturation temperature) at the refrigerant pressure. ST is calculated. In this embodiment, the refrigerant saturation temperature ST is calculated by previously storing a correspondence table between the refrigerant pressure and the refrigerant saturation temperature ST in a control device (not shown), and obtaining an approximate value of the refrigerant saturation temperature ST from the correspondence table. Note that the refrigerant saturation temperature ST may be calculated from an approximate expression that represents the relationship between the refrigerant pressure and the refrigerant saturation temperature ST.

  The refrigerant temperature T1 at the outlet of the main refrigeration cycle side of the cascade heat exchanger 305 is measured by the temperature sensor 318, and the degree of supercooling of the refrigerant at the outlet of the main refrigeration cycle side of the cascade heat exchanger 305 is measured from the refrigerant temperature T1 and the refrigerant saturation temperature ST. SC is calculated from Equation 1 below.

  The supercooling degree required by the indoor equipment is set in the control device in advance as a predetermined supercooling degree CSC, and the refrigerant supercooling degree SC and the predetermined supercooling degree CSC are compared. A difference DSC between the refrigerant supercooling degree SC and the predetermined supercooling degree CSC is calculated from Equation 2 below.

  When the refrigerant supercooling degree SC is larger than the predetermined supercooling degree CSC, that is, when DSC is larger than 0, the main refrigeration cycle side of the cascade heat exchanger 305 is excessively supercooled. Therefore, the cooling in the cascade heat exchanger 305 is suppressed by closing the expansion valve 304. In this embodiment, the opening degree of the expansion valve 304 corresponds to DSC, and the opening degree of the expansion valve 304 decreases as the DSC increases. The expansion valve 304 is closed when the DSC exceeds a predetermined value.

  When the refrigerant supercooling degree SC is smaller than the predetermined supercooling degree CSC, that is, when DSC becomes 0 or less, the main refrigeration cycle side of the cascade heat exchanger 305 is insufficiently supercooled. Therefore, the cooling in the cascade heat exchanger 305 is promoted by opening the expansion valve 304. As described above, in this embodiment, the opening degree of the expansion valve 304 corresponds to the DSC, and the opening degree of the expansion valve 304 increases as the DSC becomes smaller.

  When the refrigerant supercooling degree SC is equal to the predetermined supercooling degree CSC, the required degree of supercooling is realized, so that the valve opening degree of the expansion valve 304 is not changed. The valve opening degree control of the expansion valve 304 is not limited to this method, and a ratio between the refrigerant supercooling degree SC and the predetermined supercooling degree CSC may be used.

  Further, the temperature of the refrigerant at the inlet and outlet of the main refrigeration cycle side of the cascade heat exchanger 305 is measured by the temperature sensors 317 and 318, and the temperature difference between the inlet side temperature and the outlet side temperature is controlled as the refrigerant supercooling degree SC. May be performed.

(2) More than dew point operation mode Indoor humidity is measured by an indoor humidity sensor (not shown) that measures the humidity around the indoor piping, and a water vapor saturation temperature (water vapor saturation temperature) WT at the indoor humidity is calculated. In this embodiment, the water vapor saturation temperature WT is calculated by storing a correspondence table between the indoor humidity and the water vapor saturation temperature WT in advance in a control device (not shown), and obtaining an approximate value of the water vapor saturation temperature WT from the correspondence table. In addition, about calculation of water vapor saturation temperature WT, you may obtain | require from the approximate expression showing the relationship between indoor humidity and water vapor saturation temperature WT.

  As for the method for calculating the water vapor saturation temperature WT, an indoor temperature sensor (not shown) for measuring the ambient temperature of the indoor piping is provided, and a correspondence table between the indoor temperature and the water vapor saturation temperature WT is previously stored in a control device (not shown). An approximate value of the water vapor saturation temperature WT may be obtained from the measured indoor temperature. In addition, about calculation of water vapor saturation temperature WT, you may obtain | require from the approximate expression showing the relationship between indoor temperature and water vapor saturation temperature WT.

  The refrigerant temperature T1 at the main refrigeration cycle side outlet of the cascade heat exchanger 305 is measured by the temperature sensor 318, and the refrigerant temperature T1 is compared with the calculated water vapor saturation temperature WT. A difference DWT between the refrigerant temperature T1 and the water vapor saturation temperature WT is calculated from Equation 3 below.

  When the refrigerant temperature T1 is higher than the water vapor saturation temperature WT, that is, when the DWT is larger than 0, it is considered that condensation does not easily occur in the indoor piping, and the refrigerant temperature is high and the refrigerating capacity is insufficient. The refrigeration capacity is increased by increasing the valve opening degree of the expansion valve 304 and cooling the main refrigeration cycle side of the cascade heat exchanger 305. The valve opening degree of the expansion valve 304 corresponds to DWT, and the valve opening degree of the expansion valve 304 increases as the DWT increases.

  On the other hand, when the refrigerant temperature T1 is lower than the water vapor saturation temperature WT, that is, when the DWT is smaller than 0, dew condensation occurs in the indoor piping. Therefore, the opening degree of the expansion valve 304 is reduced to reduce the cascade heat exchanger. Condensation is prevented by suppressing the cooling on the main refrigeration cycle side of 305 and increasing the refrigerant temperature T1. As described above, the valve opening degree of the expansion valve 304 corresponds to DWT. The smaller the DWT, the closer the expansion valve 304 is. When the DWT is smaller than a predetermined value, the expansion valve 304 is closed.

(3) Refrigerant temperature constant operation mode The refrigerant temperature T1 at the main refrigeration cycle side outlet of the cascade heat exchanger 305 is measured by the temperature sensor 318. A refrigerant temperature capable of outputting the refrigeration capacity required by the indoor equipment is stored in advance in a control device (not shown) as a predetermined temperature CT, and a difference DCT between the refrigerant temperature T1 and the predetermined temperature CT is calculated from the following Equation 4.

  When the refrigerant temperature T1 is lower than the predetermined temperature CT, that is, when the DCT is 0 or less, the refrigeration capacity is excessive. Therefore, the main valve of the cascade heat exchanger 305 is reduced by reducing the valve opening degree of the expansion valve 304. Suppresses cooling on the refrigeration cycle side. The valve opening degree of the expansion valve 304 corresponds to DCT. The smaller the DCT, the more the expansion valve 304 is closed. When the DCT is smaller than a predetermined value, the expansion valve 304 is closed.

  On the other hand, when the refrigerant temperature T1 is higher than the predetermined temperature CT, that is, when the DCT is 0 or more, the refrigeration capacity is insufficient. Therefore, the cascade heat exchanger 305 is increased by increasing the valve opening degree of the expansion valve 304. The cooling of the main refrigeration cycle side is promoted. As described above, the opening degree of the expansion valve 304 corresponds to DCT, and the expansion valve 304 opens as the DCT increases.

  In any of the above operation modes, the compressor 300 is controlled by the low pressure measured by the pressure sensor 316. The operating frequency of the compressor 300 is controlled so that the low pressure is within a predetermined range, and increases in proportion to the increase in the low pressure, and decreases in proportion to the decrease in the low pressure.

  Further, the operation control of the compressor 300 is not limited to this method, and the operating frequency increases and the valve opening decreases when the valve opening increases in conjunction with the valve opening of the expansion valve 304 in each operation mode. The operating frequency may be reduced when the operation is performed.

  When the compressor 300 is a constant speed compressor, the compressor 300 is stopped when the low-pressure pressure becomes equal to or lower than the lower limit value of the predetermined range, and is started when the low pressure becomes equal to or higher than the lower limit value of the predetermined range. Further, the operation control of the compressor 300 is not limited to this method, and operates when the valve opening degree of the expansion valve 304 in each operation mode becomes a predetermined value or more and stops when the valve opening degree becomes a predetermined value or less. The method to do is also good.

  Next, linkage operation control of the refrigeration apparatus 1 and the supercooling unit 3 will be described. When the refrigeration capacity becomes excessive in the indoor facilities of the main refrigeration cycle, the compressors 100 and 101 of the refrigeration apparatus 1 are stopped because the suction side pressure of the compressor of the refrigeration apparatus 1 is greatly reduced. The refrigerant is not circulated.

  Since the supercooling unit 3 is operated and controlled by measuring the temperature or pressure on the main refrigeration cycle side of the cascade heat exchanger 305, the refrigeration required by the main refrigeration cycle when the refrigerant in the main refrigeration cycle is not circulating. The ability cannot be measured, and there is a possibility of driving alone (idling).

  In order to cope with this, the supercooling unit 3 is used for operation control of the refrigerating apparatus 1 when the compressors 100 and 101 of the refrigerating apparatus 1 are stopped although the compressor 300 of the subcooling unit 3 is not stopped. The predetermined pressure I is reset to a value lower than the original value, and the stop of the compressor of the refrigeration apparatus 1 is suppressed. Accordingly, since the refrigerant circulates through the main refrigeration cycle, the supercooling unit 3 can perform an operation corresponding to the refrigeration capacity currently required by the main refrigeration cycle. When the suction side pressure of the compressor of the refrigeration apparatus 1 becomes larger than the original predetermined pressure I, the value of the predetermined pressure I is returned to the original value.

  Similarly, when the compressor 300 of the supercooling unit 3 is not stopped, but the compressors 100 and 101 of the refrigeration apparatus 1 are stopped, the supercooling unit 3 has a low pressure pressure used for operation control of the compressor 300. The predetermined range is shifted to a higher range. Thereby, since the output of the compressor 300 is lower than usual, the supercooling of the refrigerant in the main refrigeration cycle by the supercooling unit 3 is suppressed, and the operation of the main refrigeration cycle is promoted. Therefore, since the refrigerant circulates through the main refrigeration cycle, the supercooling unit 3 can perform an operation corresponding to the refrigeration capacity currently required by the main refrigeration cycle. When the compressor 300 low pressure becomes larger than the upper limit of the original predetermined range, the value in the predetermined range is returned to the original value.

  When the compressor of the main refrigeration cycle is stopped, there are many situations where the refrigeration capacity of the main refrigeration cycle is excessive. Therefore, it is determined that the refrigeration capacity is excessive and the compressor regardless of the operation status of the supercooling unit 3. Operation control may be performed to stop 300.

It is a refrigerant circuit figure of the conventional freezing apparatus. It is a refrigerant circuit diagram of the refrigerating device to which the present invention is applied. It is a refrigerant circuit figure of a refrigerating device provided with an internal heat exchanger to which the present invention is applied.

Explanation of symbols

100, 101 Compressor 102 Oil separator 103 Liquid receiver 104 Strainer 105 Accumulator 106 Strainer (for oil)
107,108 Solenoid valve (for oil)
109, 112 Strainer (for liquid injection)
110, 113 Expansion valve (for liquid injection)
111, 114 Solenoid valve (for liquid injection)
200 Condenser 300 Compressor 301 Oil separator 302 Condenser 303 Receiving device 304 Expansion valve 305 Cascade heat exchanger 306 Accumulator 307 Strainer (for oil)
308 Solenoid valve (for oil)
309 Strainer (for liquid injection)
310 Expansion valve (for liquid injection)
311 Solenoid valve (for liquid injection)
312 High pressure sensor 313 High pressure sensor 314 Sub refrigeration cycle side inlet temperature sensor 315 Sub refrigeration cycle side outlet temperature sensor 316 Low pressure sensor 317 Main refrigeration cycle side inlet temperature sensor 318 Main refrigeration cycle side outlet temperature sensor 319 Main refrigeration cycle side outlet Pressure sensor 320 Internal heat exchanger

Claims (5)

In the main refrigeration cycle consisting of a compressor, a refrigeration apparatus equipped with a condenser, a decompression apparatus, and an indoor facility equipped with an evaporator,
A sub-refrigeration cycle provided with a supercooling heat exchanger that supercools the refrigerant flowing out of the condenser between the condenser and the pressure reducing device,
The sub-refrigeration cycle includes a compressor, a decompression device, a supercooling device including the supercooling heat exchanger, and a condensing unit including a condenser. The refrigeration system of claim 1,
The refrigeration system, wherein the condensing unit is installed outdoors. In the refrigeration system according to claim 1 and claim 2,
Provided with indoor piping for connecting the indoor equipment by piping,
The indoor piping is designed to meet the HCFC refrigerant specifications,
The refrigerant used by the main refrigeration cycle and the sub refrigeration cycle is an HFC refrigerant. The refrigeration system according to any one of claims 1 to 3,
The refrigeration system, wherein an evaporation temperature of the main refrigeration cycle is lower than an evaporation temperature of the sub refrigeration cycle. The refrigeration system according to any one of claims 1 to 4,
The refrigeration system, wherein the condenser of the main refrigeration system is provided separately from the refrigeration apparatus.