JP2015178921A - Refrigeration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve space efficiency and stability while improving heat exchanging efficiency in a gas cooler of each refrigerant circuit, in a refrigeration device in which a high stage-side refrigerant circuit and a low stage-side refrigerant circuit are cascade-connected.SOLUTION: A low stage-side gas cooler is composed of first low stage-side gas coolers 23A, 23B positioned at an upstream side with respect to a refrigerant flow, and second low stage-side gas coolers 26A, 26B positioned at the downstream side. A first air channel 68 and a second air channel 69 in which air is ventilated by blowers 51, 52 for gas coolers, are disposed in a refrigerator unit 3. The first low stage-side gas cooler and high stage-side gas coolers 11A, 11B are disposed in the first air channel, and the second low stage-side gas cooler is disposed in the second air channel.

Description

  The present invention relates to a refrigeration apparatus in which a high-stage refrigerant circuit and a low-stage refrigerant circuit are cascade-connected and carbon dioxide is sealed as a refrigerant in each refrigerant circuit.

  Conventionally, for example, in stores such as convenience stores and supermarkets, a plurality of showcases that display and sell products while cooling products in a display room are installed. Each showcase is provided with an evaporator for cooling the display room, and refrigerant is supplied to the evaporator from a refrigerator unit installed outside the store (for example, Patent Document 1). reference).

  Also, carbon dioxide has come to be used as a refrigerant in this kind of showcase due to recent global environmental problems, but a relatively large compressor is required to compress this carbon dioxide. Therefore, the high stage side refrigerant circuit (high temperature side refrigerant circulation circuit) and the low stage side refrigerant circuit (low temperature side refrigerant circulation circuit) that constitute independent refrigerant closed circuits are cascade-connected, and the R410A refrigerant of the high stage side refrigerant circuit is connected. Has been developed to cool the high-pressure side carbon dioxide refrigerant in the low-stage refrigerant circuit to obtain a required refrigeration capacity in the evaporator of the low-stage refrigerant circuit (for example, Patent Document 2). reference).

JP-A-9-145230 JP 2012-193866 A

  However, in Patent Document 2, the condenser of the high stage side refrigerant circuit and the intermediate cooler of the low stage side refrigerant circuit are installed separately in separate casings, or the condenser of the high stage side refrigerant circuit is divided. As a result, a part of the space is installed in the housing on the intermediate cooler side, which increases the installation space. This becomes a significant problem when a plurality of low-stage refrigerant circuits are used for one high-stage refrigerant circuit.

  Further, in such a configuration, there is a risk that air cooling of the intermediate cooler of the low-stage refrigerant circuit before the cascade capacitor becomes insufficient, and carbon dioxide is used as a refrigerant in both the high-stage refrigerant circuit and the low-stage refrigerant circuit. When used, there is a problem in that the heat radiation performance of both carbon dioxide refrigerants (the heat radiation performance of each refrigerant circuit) is insufficient, resulting in a decrease in operating efficiency.

  The present invention has been made in order to solve the conventional technical problem, and in a refrigeration apparatus in which a high-stage refrigerant circuit and a low-stage refrigerant circuit are cascade-connected, heat exchange in a gas cooler of each refrigerant circuit The purpose is to improve space efficiency and stability while improving efficiency.

  In order to solve the above problems, the present invention provides a high stage side compressor including a high stage side compressor, a high stage side gas cooler, a high stage side expansion valve, a high stage side evaporator, and a low stage side compressor. A low stage side gas cooler, a supercooling heat exchanger, a low stage side expansion valve, a low stage side refrigerant circuit including a low stage side evaporator, a high stage side evaporator and a supercooling heat exchanger And a cascade heat exchanger configured to evaporate the refrigerant in the high-stage evaporator and cool the refrigerant flowing through the supercooling heat exchanger, and each refrigerant circuit is filled with carbon dioxide as a refrigerant. Each compressor, each gas cooler, a cascade heat exchanger, and a refrigerator unit in which a gas cooler blower for air-cooling each gas cooler is installed, and the low-stage gas cooler is disposed upstream of the refrigerant flow A first low-stage gas cooler located in the And a first air passage and a second air passage that are ventilated by a gas cooler blower in the refrigerator unit, and the first low-stage gas cooler and the high-stage side. The gas cooler is installed in the first air passage, and the second low-stage gas cooler is installed in the second air passage.

  A refrigeration apparatus according to a second aspect of the present invention is characterized in that, in the above invention, the first low-stage gas cooler is disposed on the air downstream side in the first air passage with respect to the high-stage gas cooler.

  A refrigeration apparatus according to a third aspect of the present invention includes the first and second gas cooler fans in each of the above-described inventions, the first gas cooler fan is installed in the first air passage, and the second gas cooler fan is disposed in the first air passage. It is characterized by having been installed in 2 air passages.

  According to a fourth aspect of the present invention, there is provided a refrigeration apparatus comprising a partition plate for partitioning the inside of the refrigerator unit into an upper machine chamber and a lower machine chamber in each of the above inventions, wherein the first air passage is in the lower machine chamber and the second air passage is Is constructed in the upper machine room.

  A refrigeration apparatus according to a fifth aspect of the present invention is characterized in that in the above invention, each compressor is installed in the lower machine room, and a cascade heat exchanger is installed in the upper machine room.

  According to a sixth aspect of the present invention, there is provided a refrigeration apparatus comprising the first and second low-stage refrigerant circuits and the first and second cascade heat exchangers provided in the low-stage refrigerant circuits, respectively. Any two of the high stage compressor of the high stage refrigerant circuit and the low stage compressor of each low stage refrigerant circuit are installed in the lower machine room, and one is installed in the upper machine room It is characterized by.

  ADVANTAGE OF THE INVENTION According to this invention, the high stage side refrigerant circuit provided with the high stage side compressor, the high stage side gas cooler, the high stage side expansion valve, and the high stage side evaporator, the low stage side compressor, and the low stage side gas cooler. A high-stage heat exchanger, a low-stage side expansion valve, a low-stage side refrigerant circuit including a low-stage side evaporator, a high-stage evaporator and a supercooling heat exchanger, And a cascade heat exchanger that cools the refrigerant flowing in the supercooling heat exchanger by evaporating the refrigerant in the side evaporator, and in each refrigerant circuit, carbon dioxide is encapsulated as a refrigerant. Each of the gas coolers, the cascade heat exchanger, and a refrigerator unit in which a gas cooler blower for air-cooling each gas cooler is installed, and the low-stage gas cooler is positioned upstream of the refrigerant flow. Low-stage gas cooler and a second low-stage gas cooler located downstream thereof And the first air passage and the second air passage that are ventilated by the gas cooler blower in the refrigerator unit, and the first low-stage gas cooler and the high-stage gas cooler are provided in the first air passage. Since the second low-stage gas cooler is installed in the air path and the second low-stage gas cooler is installed in the second air path, the second low-stage gas cooler located downstream of the refrigerant flow is used as the second air path. Air can be effectively cooled by the ventilated air.

  On the other hand, the first low-stage gas cooler located on the upstream side is installed in the first air passage together with the high-stage gas cooler, so that the high-stage gas cooler is separated from the first low-stage gas cooler. The refrigerator unit can be downsized as compared with the case where it is installed on the road. This is particularly effective when a plurality of (first and second) low-stage refrigerant circuits are provided as in the sixth aspect of the invention.

  In this case, if the first low-stage gas cooler is arranged on the downstream side of the air in the first air passage with respect to the high-stage gas cooler as in the second aspect of the invention, the first air passage is ventilated. The high stage side gas cooler can be first air-cooled by air, and the high stage side gas cooler can be effectively cooled. In addition, air that has passed through the high-stage gas cooler is vented to the first low-stage gas cooler, but the first low-stage gas cooler is located upstream of the refrigerant of the second low-stage gas cooler. Thus, the refrigerant flowing into the second low-stage gas cooler can be pre-cooled by the first low-stage gas cooler. As a result, the heat exchange efficiency in the gas coolers of the high stage side refrigerant circuit and the low stage side refrigerant circuit as a whole can be remarkably improved.

  According to a third aspect of the present invention, the first and second gas cooler fans are provided, the first gas cooler fan is installed in the first air passage, and the second gas cooler fan is installed in the second air passage. If installed, each air passage can be independently ventilated by each gas cooler blower, and the high stage gas cooler and each low stage gas cooler can be air-cooled more effectively.

  Further, as in the invention of claim 4, the inside of the refrigerator unit is divided into an upper machine room and a lower machine room by a partition plate, and the first air passage is formed in the lower machine room and the second air passage is formed in the upper machine room. By doing so, the installation space of the refrigerator unit can be reduced as compared with the case where the air paths are arranged in parallel. At this time, the high stage side gas cooler and the first low stage side gas cooler are installed in the first wind path of the lower machine room, and the second low stage side gas cooler is installed in the second wind path of the upper machine room. As a result, the weight distribution in the lower part of the refrigerator unit can be increased, and the stability is improved.

  In this case, if each compressor is installed in the lower machine room and a cascade heat exchanger is installed in the upper machine room as in the invention of claim 5, each heavy compressor is arranged in the lower part of the refrigerator unit. As a result, the stability is further improved.

  In particular, the refrigeration apparatus as in the invention of claim 6 includes first and second low-stage refrigerant circuits and first and second cascade heat exchangers provided in the low-stage refrigerant circuits, respectively. If there is, install two of the high-stage compressor in the high-stage refrigerant circuit and the low-stage compressor in each low-stage refrigerant circuit in the lower machine room, and install one in the upper machine room Even when the first and second low-stage refrigerant circuits are included, the refrigerator unit can be reduced in size and stability can be improved.

It is a refrigerant circuit figure of the refrigerating device of one example to which the present invention is applied. It is a front view which shows the internal structure of the refrigerator unit of the freezing apparatus of FIG. It is a figure explaining the 1st and 2nd air path in the refrigerator unit of FIG.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a refrigerant circuit diagram of a refrigerating apparatus 1 according to an embodiment to which the present invention is applied.

(1) Refrigerant circuit configuration of refrigeration apparatus 1 The refrigeration apparatus 1 of the embodiment is installed outside the store in a plurality of showcases 2A and 2B (two in the embodiment) installed in a store such as a convenience store or a supermarket. The refrigerant is supplied from the refrigerating machine unit 3, and includes one high-stage refrigerant circuit 4 and a plurality of (two systems in the embodiment) low-stage refrigerant circuits (first low-stage refrigerant circuit 6A). And a second low-stage refrigerant circuit 6B).

  The high-stage side refrigerant circuit 4 of the embodiment includes a high-stage side compressor 7 composed of a scroll compressor, first and second (plural) high-stage side gas coolers 11A and 11B, a high-stage side expansion valve 13, and the like. , First and second (plural) high-stage evaporators 16A and 16B. In this case, the first and second high-stage gas coolers 11A and 11B are connected to the branch pipes 9A and 9B branched from the discharge pipe 8 of the high-stage compressor 7, respectively, and are parallel to each other. Further, the outlet pipe 12A of the first high-stage side gas cooler 11A and the outlet pipe 12B of the second high-stage side gas cooler 11B are merged and connected to the inlet of the high-stage side expansion valve 13 via the inlet pipe 20. . That is, the high stage side gas coolers 11A and 11B are connected in parallel between the high stage side compressor 7 and the high stage side expansion valve 13.

  The outlet of the high stage side expansion valve 13 is connected to the inlet of the second high stage side evaporator 16B via the outlet pipe 15. The outlet pipe 17B of the second high stage evaporator 16B is connected to the inlet of the first high stage evaporator 16A, and the outlet pipe 17A of the first high stage evaporator 16A is connected to the high stage side. The suction pipe 18 of the compressor 7 is connected. That is, each of the high-stage evaporators 16A and 16B is connected in series to the outlet of the high-stage side expansion valve 13, thereby constituting the refrigeration cycle of the high-stage side refrigerant circuit 4. The high-stage refrigerant circuit 4 contains a predetermined amount of carbon dioxide as a refrigerant.

  On the other hand, the low-stage refrigerant circuits 6A and 6B have the same configuration. First, the low-stage refrigerant circuit 6A of the embodiment includes a low-stage compressor 21A, which is also a scroll compressor, and a first low-stage gas cooler connected to the discharge pipe 22A of the low-stage compressor 21A. 23A, a second low-stage gas cooler 26A connected to the outlet pipe 24A and downstream of the first low-stage gas cooler 23A, and an outlet pipe 27A of the second low-stage gas cooler 26A The subcooling heat exchanger 28A, the pressure adjusting expansion valve 31A connected to the outlet pipe 29A of the subcooling heat exchanger 28A, and the outlet 35A to the outlet pipe 32A of the pressure adjusting expansion valve 31A And a series circuit of a low stage side expansion valve 34A and a low stage side evaporator 36A of the showcase 2A connected to the connecting pipe 33A.

  The low stage side expansion valve 34A and the low stage side evaporator 36A are installed in the showcase 2A. An electromagnetic valve 37A is connected to the outlet side of the low-stage evaporator 36A in the showcase 2A, and the outlet of the electromagnetic valve 37A is connected to the accumulator 39A via the crossover piping 38A, the connection port 40A, and the inlet piping 42A. The outlet side of the accumulator 39A is connected to the suction pipe 41A of the low stage compressor 21A to constitute a refrigeration cycle. The accumulator 39A is a tank having a predetermined capacity.

  On the other hand, the low-stage refrigerant circuit 6B includes a low-stage compressor 21B, which is also a scroll compressor, a first low-stage gas cooler 23B connected to the discharge pipe 22B of the low-stage compressor 21B, A second low-stage gas cooler 26B connected to the outlet pipe 24B and downstream of the first low-stage gas cooler 23B, and a supercooling connected to the outlet pipe 27B of the second low-stage gas cooler 26B. The heat exchanger 28B for pressure, the pressure adjusting expansion valve 31B connected to the outlet pipe 29B of the subcooling heat exchanger 28B, and the outlet pipe 32B of the pressure adjusting expansion valve 31B are connected via the connection port 35B. And a series circuit of a low stage side expansion valve 34B and a low stage side evaporator 36B of the showcase 2B connected to the transition pipe 33B.

  The low stage side expansion valve 34B and the low stage side evaporator 36B are installed in the showcase 2B. An electromagnetic valve 37B is connected to the outlet side of the low-stage evaporator 36B in the showcase 2B, and the outlet of the electromagnetic valve 37B is connected to the accumulator 39B via the crossover piping 38B, the connection port 40B, and the inlet piping 42B. The outlet side of the accumulator 39B is connected to the suction pipe 41B of the low-stage compressor 21B to constitute a refrigeration cycle. This accumulator 39B is also a tank having a predetermined capacity. Note that a predetermined amount of carbon dioxide is sealed as a refrigerant in each of the low-stage refrigerant circuits 6A and 6B.

  Then, the first high-stage evaporator 16A of the high-stage refrigerant circuit 4 and the supercooling heat exchanger 28A of the low-stage refrigerant circuit 6A are provided in a heat exchange relationship so that the first cascade heat exchanger 43A The second cascade heat exchanger is configured such that the second high-stage evaporator 16B of the high-stage refrigerant circuit 4 and the supercooling heat exchanger 28B of the low-stage refrigerant circuit 6B are provided in a heat exchange relationship. 43B is configured. Further, the above-described crossover pipes 33A and 33B and the crossover pipes 38A and 38B are pipes extending from the refrigerator unit 3 to the showcases 2A and 2B.

  In the figure, 44A and 44B are pressure sensors attached to the discharge pipes 22A and 22B of the low-stage compressors 21A and 21B of the low-stage refrigerant circuits 6A and 6B, respectively, from the low-stage compressors 21A and 21B. The pressure of the discharged high-pressure refrigerant is detected. Reference numeral 46 in the figure denotes a pressure sensor that is attached to the discharge pipe 8 of the high-stage compressor 7 and detects the high-pressure side pressure of the high-stage refrigerant circuit 4. Further, in the figure, 47 is a temperature sensor that detects the temperature of the refrigerant that is attached to the outlet pipe 17A and exits the first high-stage evaporator 16A.

  In the figure, reference numerals 51 and 52 denote first and second gas cooler blowers. The first gas cooler blower 51 includes, as will be described in detail later, the high-stage gas coolers 11A and 11B and the low-stage refrigerant circuits 6A and 6B. The first low-stage gas coolers 23A, 23B are ventilated to cool them, and the second gas cooler blower 52 is ventilated to the second low-stage gas coolers 26A, 26B of the low-stage refrigerant circuits 6A, 6B. And air cool. In the figure, reference numeral 53 denotes a temperature sensor for detecting the outside air temperature. Furthermore, in the figure, 48 is a control device on the refrigerator unit 3 side, and the operating frequency of the high stage compressor 7 of the high stage refrigerant circuit 4 based on the output of each sensor 44A, 44B, 46, 47, 53, etc. , The opening degree of the high stage side expansion valve 13, the operating frequency of the low stage side compressors 21A and 21B of the low stage side refrigerant circuits 6A and 6B, the valve opening degree of the pressure adjusting expansion valves 31A and 31B, and for each gas cooler The operation of the blowers 51 and 52 is controlled.

  The showcases 2A and 2B side low-stage expansion valves 34A and 34B and the solenoid valves 37A and 37B are based on the temperature in the display room and the temperature of the cold air blown out there by the control device of each showcase 2A and 2B. The control devices of the showcases 2A and 2B and the control device 48 of the refrigerator unit 3 are centrally controlled by an integrated control device provided in the store, and operate in cooperation with each other.

(2) Operation of the refrigeration apparatus 1 With the above configuration, the control device 48 controls the high stage compressor 7 of the high stage refrigerant circuit 4 and the low stage compressors 21A, 21B of the low stage refrigerant circuits 6A, 6B, When each of the gas cooler blowers 51 and 52 is operated, after the high-temperature and high-pressure refrigerant (carbon dioxide) compressed by the high-stage compressor 7 is discharged to the discharge pipe 8 and divided into the branch pipes 9A and 9B, It flows into each high stage side gas cooler 11A, 11B. The refrigerant that has flowed into the high-stage gas coolers 11A and 11B is cooled in a supercritical state by the gas cooler blower 51, and the temperature decreases.

The high-temperature and high-pressure refrigerant (carbon dioxide) compressed by the high-stage compressor 7 is discharged to the discharge pipe 8 and divided into the branch pipes 9A and 9B, and then flows into the high-stage gas coolers 11A and 11B. The refrigerant that has flowed into the high-stage gas coolers 11A and 11B is cooled in a supercritical state by the gas cooler blower 51, and the temperature decreases.

  Then, the refrigerant cooled by the high-stage gas coolers 11A and 11B merges through the outlet pipes 12A and 12B, and then flows into the high-stage expansion valve 13 where it is throttled (decompression), and then the outlet pipe 15 First, the refrigerant flows into the second high-stage evaporator 16B constituting the second cascade heat exchanger 43B, evaporates, and flows through the supercooling heat exchanger 28B of the second low-stage refrigerant circuit 6B. Is cooled (supercooled).

  The refrigerant that has exited the second high-stage evaporator 16B flows into the first high-stage evaporator 16A that constitutes the first cascade heat exchanger 43A through the outlet pipe 17B, and then evaporates. The refrigerant flowing through the supercooling heat exchanger 28A of the first low-stage refrigerant circuit 6A is cooled (supercooling). And the refrigerant | coolant which came out of this 1st high stage side evaporator 16A repeats the circulation sucked into the high stage side compressor 7 from the suction piping 18 via the exit piping 17A.

  On the other hand, the high-temperature and high-pressure refrigerant (carbon dioxide) compressed by the low-stage compressor 21A of the first low-stage refrigerant circuit 6A is discharged to the discharge pipe 22A and flows into the first low-stage gas cooler 23A. The refrigerant that has flowed into the first low-stage gas cooler 23A is cooled in a supercritical state by the gas cooler blower 51, decreases in temperature, and then flows into the second low-stage gas cooler 26A through the outlet pipe 24A. To do. The refrigerant that has flowed into the second low-stage gas cooler 26A is cooled in a supercritical state by the gas cooler blower 52 and further drops in temperature, and then constitutes the first cascade heat exchanger 43A via the outlet pipe 27A. It flows into the supercooling heat exchanger 28A.

  The refrigerant that has flowed into the supercooling heat exchanger 28A is cooled (supercooled) by the refrigerant of the high-stage refrigerant circuit 4 that evaporates in the first high-stage evaporator 16A, and the temperature further decreases. The pressure adjustment expansion valve 31A is reached via the outlet pipe 29A.

  The high pressure side refrigerant in the low stage side refrigerant circuit 6A is throttled by the pressure adjusting expansion valve 31A, and exits from the refrigerator unit 3 through the outlet pipe 32A through the connection port 35A. The refrigerant discharged from the refrigerator unit 3 enters the showcase 2A through the crossover pipe 33A. Then, the low-stage expansion valve 34A is reached, throttled there, and then flows into the low-stage evaporator 36A to evaporate. The display chamber of each showcase 2A is cooled to a predetermined temperature by the endothermic action at this time.

  The refrigerant that has exited the low-stage evaporator 36A of the showcase 2A passes through the solenoid valve 37A (when the showcase 2A is cooled, the solenoid valve 37A is open) and the connecting pipe 38A via the transition pipe 38A. The refrigerator unit 3 is entered from 40A. Then, it flows into the accumulator 39A from the inlet pipe 42A. The refrigerant flowing into the accumulator 39A is gas-liquid separated there and repeats circulation in which the gas refrigerant is sucked into the low-stage compressor 21A via the suction pipe 41A.

  On the other hand, the high-temperature and high-pressure refrigerant (carbon dioxide) compressed by the low-stage compressor 21B of the second low-stage refrigerant circuit 6B is discharged to the discharge pipe 22B and flows into the first low-stage gas cooler 23B. The refrigerant that has flowed into the first low-stage gas cooler 23B is cooled in a supercritical state by the gas cooler blower 51. After the temperature has dropped, the refrigerant flows into the second low-stage gas cooler 26B through the outlet pipe 24B. To do. The refrigerant that has flowed into the second low-stage gas cooler 26B is cooled in a supercritical state by the gas cooler blower 52, and further drops in temperature, and then constitutes the second cascade heat exchanger 43B via the outlet pipe 27B. It flows into the supercooling heat exchanger 28B.

  The refrigerant that has flowed into the supercooling heat exchanger 28B is cooled (supercooled) by the refrigerant in the high-stage refrigerant circuit 4 that evaporates in the second high-stage evaporator 16B, and the temperature further decreases. The pressure adjustment expansion valve 31B is reached via the outlet pipe 29B.

  The high pressure side refrigerant in the low stage side refrigerant circuit 6B is throttled by the pressure adjusting expansion valve 31B, and exits the refrigerator unit 3 through the outlet pipe 32B and through the connection port 35B. The refrigerant discharged from the refrigerator unit 3 enters the showcase 2B through the crossover pipe 33B. After reaching the low stage side expansion valve 34B and being throttled there, it flows into the low stage side evaporator 36B and evaporates. The display chamber of each showcase 2B is cooled to a predetermined temperature by the endothermic action at this time.

  Then, the refrigerant that has exited the low-stage evaporator 36B of the showcase 2B passes through the solenoid valve 37B (when the showcase 2B is cooled, the solenoid valve 37B is open) and the connecting pipe 38B via the transition pipe 38B. The refrigerator unit 3 is entered from 40B. And it flows into the accumulator 39B from the inlet piping 42B. The refrigerant flowing into the accumulator 39B is gas-liquid separated there and repeats circulation in which the gas refrigerant is sucked into the low-stage compressor 21B through the suction pipe 41B.

  The control device 48 controls the operating frequency of the high-stage compressor 7 based on the temperature of the refrigerant that has exited the first high-stage evaporator 16 </ b> A detected by the temperature sensor 47. At this time, the control device 48 controls the operating frequency of the high-stage compressor 7 so that the required supercooling of the high-pressure refrigerant in the low-stage refrigerant circuits 6A and 6B can be obtained in the cascade heat exchangers 43A and 43B. .

  Further, in the embodiment, the control device 48 calculates the optimum high-pressure side pressure of the low-stage refrigerant circuits 6A and 6B based on the outside air temperature detected by the temperature sensor 53, and uses it as a target value for each pressure adjusting expansion valve. The valve opening degree of 31A, 31B is controlled. In this case, the control device 48 holds in advance information indicating the relationship between the outside air temperature and the optimum high-pressure side pressure of the low-stage refrigerant circuit 6A (6B) at that time, and based on this information, the low-stage refrigerant The optimum value of the high-pressure side pressure of the circuit 6A (6B) is calculated, and the expansion valve 31A, 31B for pressure adjustment is controlled using this value as a target value. Here, the optimum value of the high-pressure side pressure means the high-pressure side pressure of the low-stage refrigerant circuit 6A (6B) at which the operating efficiency COP is maximized or close to it.

  Further, the control device 48 determines the valve opening degree of the expansion valve 13 based on the high-pressure side pressure of the high-stage refrigerant circuit 4 detected by the pressure sensor 46. The expansion valve for pressure adjustment of the low-stage refrigerant circuits 6A and 6B described above. By controlling in the same manner as 31A and 31B, the high pressure side pressure of the high stage side refrigerant circuit 4 is controlled to an appropriate value similar to the above (the target value of the high pressure side pressure of the high stage side refrigerant circuit 4).

  As described above, the refrigerant in the high-stage side refrigerant circuit 4 is evaporated in the high-stage evaporators 16A and 16B of the cascade heat exchangers 43A and 43B, and the low-stage refrigerants flowing through the supercooling heat exchangers 28A and 28B. Even when carbon dioxide is used as a refrigerant by supercooling the high-pressure side refrigerant of the circuits 6A and 6B, the compressors 7, 21A and 21B of the refrigerant circuits 4, 6A and 6B are relatively large (high capacity). The required cooling capacity can be obtained in the low-stage evaporators 36A and 36B of the showcases 2A and 2B without using the compressor.

  In addition, the refrigerant that has exited the low-stage evaporators 36A and 36B of the low-stage refrigerant circuits 6A and 6B does not exchange heat with the high-pressure refrigerant of the low-stage refrigerant circuits 6A and 6B. Since it is configured to be sucked into the low-stage compressors 21A and 21B of 6A and 6B, an abnormal increase in the high-pressure side pressure of the low-stage refrigerant circuits 6A and 6B is prevented, particularly in summer when the outside air temperature becomes high. In addition, the low-stage compressors 21A and 21B can suck the refrigerant having a high density, which improves the efficiency.

  In addition, since the accumulators 39A and 39B are provided on the suction side of the low-stage compressors 21A and 21B, liquid back to the low-stage compressors 21A and 21B is prevented. Further, since the accumulators 39A and 39B function as a liquid reservoir, a sufficient amount of carbon dioxide refrigerant can be sealed in the low-stage refrigerant circuits 6A and 6B.

  Further, since the cascade heat exchangers 43A and 43B supercool the refrigerant that has exited the low-stage gas coolers 26A and 26B, the low-stage refrigerant circuit 6A cooled by the low-stage gas coolers 23A, 23B, 26A, and 26B, The 6B carbon dioxide refrigerant is further supercooled by the cascade heat exchangers 43A and 43B, and the cooling capacity can be further improved.

  Further, in this embodiment, since two low-stage refrigerant circuits 6A and 6B and two cascade heat exchangers 43A and 43B respectively provided in the low-stage refrigerant circuits 6A and 6B are provided, one The high-stage side refrigerant circuit 4 can supercool the high-pressure side refrigerants of the two systems (plurality) of the low-stage refrigerant circuits 6A and 6B.

  Furthermore, in the embodiment, the high stage side refrigerant circuit 4 configures each cascade heat exchanger 43B, 43A in series with the outlet of the high stage side expansion valve 13 connected to the outlets of the high stage side gas coolers 11A, 11B. Two (plural) high-stage evaporators 16B and 16A are connected, and the operating frequency of the high-stage compressor 7 is controlled by the temperature of the refrigerant discharged from the first high-stage evaporator 16A on the downstream side. Therefore, a relatively simple configuration can be achieved, and the liquid back to the high-stage compressor 7 can be appropriately eliminated.

(3) Layout in Refrigeration Unit 3 Next, the structure of the refrigeration unit 3 of the refrigeration apparatus 1 of the embodiment and the layout of each device installed therein will be described with reference to FIGS. The refrigerator unit 3 includes an outer case 61 composed of a base 56 at the bottom, left and right side panels 57 and 58, an upper top panel 59 and the like, and each device is housed in the outer case 61. A machine room 60 is configured. A ceiling partition plate 62 is attached to the lower side of the top panel 59 with a space therebetween, and an electrical board including the control device 48 is accommodated between the ceiling partition plate 62 and the top panel 59. A substrate chamber 63 is formed.

  Further, the inside of the machine room 60 of the exterior case 61 below the top partition plate 62 is divided into left and right by a vertical partition plate 64, and the left and right machine chambers 60 of the vertical partition plate 64 are partway in the vertical direction. In this section, the upper machine room 60A and the lower machine room 60B are partitioned by the left and right partition plates 66 and 67, whereby the first wind flows into the lower machine room 60B below the partition plate 66 on the left side of the vertical partition plate 64. A path 68 is configured, and a second air path 69 independent of the first air path 68 is configured in the upper machine chamber 60A on the left side of the vertical partition plate 64 and above the partition plate 66, and the vertical partition plate A first storage chamber 71 is formed in the lower machine chamber 60B below the partition plate 67 on the right side of 64, and a second storage chamber 72 in the upper machine chamber 60A above the partition plate 67 on the right side of the vertical partition plate 64. Are each configured.

  The front and rear surfaces of the first and second storage chambers 71 and 72 are concealed by a detachable panel (with a vent) not shown. Further, as shown in FIG. 3, the rear surfaces of the first and second air passages 68 and 69 are air suction ports 73 and 74 (with a removable breathable cover (not shown) attached), and the front surfaces are similar air. The outlets 76 and 77 are provided.

  And the 1st and 2nd high stage side gas coolers 11A and 11B of the high stage side refrigerant circuit 4 are installed up and down on the air inlet 73 side (upstream side of the air flow) of this first air passage 68, On the air discharge port 76 side (downstream side of the airflow), the first low stage side gas cooler 23A of the first low stage side refrigerant circuit 6A and the first low stage side of the second low stage side refrigerant circuit 6B. Gas coolers 23B are installed up and down. A first gas cooler blower 51 is installed in the first air passage 68 on the air discharge port 76 side of the low-stage gas coolers 23A and 23B.

  Further, in the second air passage 69, there are a second low-stage gas cooler 26A of the first low-stage refrigerant circuit 6A and a second low-stage gas cooler 26B of the second low-stage refrigerant circuit 6B. It is installed up and down. A second gas cooler blower 52 is installed in the second air passage 69 on the air discharge port 77 side of the low stage side gas coolers 26A, 26B.

  The high stage compressor 7 of the high stage refrigerant circuit 4 and the low stage compressor 21B and the accumulator 39B of the second low stage refrigerant circuit 6B are the base 56 in the lower first storage chamber 71. It is installed on the top. Further, the low-stage compressor 21A and the accumulator 39A of the first low-stage refrigerant circuit 6A are installed on the partition plate 67 in the second storage chamber 72 on the upper side, and the cascade heat exchangers 43A and 43B are installed. Is also stored in the second storage chamber 72.

  Each of the connection ports 35A, 35B, 40A, 40B is provided on the side panel 58 side opposite to the first air passage 68 of the first storage chamber 71 and exposed outside the outer case 61. .

  With the above configuration, when the first gas cooler blower 51 is operated, outside air is sucked from the air suction port 73 of the first air passage 68 as shown by arrows in FIG. , 11B. Thereby, the high stage side gas coolers 11A and 11B of the high stage side refrigerant circuit 4 are effectively air-cooled by fresh outside air that does not exchange heat with other devices. The air that has cooled the high-stage gas coolers 11A and 11B is then passed through the first low-stage gas coolers 23A and 23B, and then discharged from the air discharge port 76 to the heat exhaust side. As a result, the first low-stage gas coolers 23A and 23B located upstream of the refrigerant in the low-stage refrigerant circuits 6A and 6B are cooled, but the temperature of the air passes through the high-stage gas coolers 11A and 11B. This is a precooling effect because of the elevated air.

  On the other hand, when the second gas cooler blower 52 is operated, outside air is sucked from the air suction port 74 of the second air passage 69 as shown by the arrows in FIG. 3, and the second low-stage gas coolers 26A, 26B. After being ventilated, the air is discharged from the air discharge port 77 to the heat exhaust side. Thereby, in each low stage side refrigerant circuit 6A, 6B, 2nd low stage side gas cooler 26A, 26B located in the downstream of the refrigerant | coolant of 1st low stage side gas cooler 23A, 23B is also this with another apparatus. Air is effectively cooled by fresh outside air that is not heat exchanged. As a result, the refrigerant in the low-stage refrigerant circuits 6A and 6B precooled by the first low-stage gas coolers 23A and 23B is more strongly cooled in the second low-stage gas coolers 26A and 26B and is subcooled. Will flow into the heat exchangers 28A and 28B.

  Note that the air flow formed by the gas cooler blower 51 is partially ventilated also in the first storage chamber 71, so that the high-stage compressor 7 and the low-stage compressor 21B are also air-cooled. In addition, since the air flow formed by the gas cooler blower 52 is partially ventilated in the second storage chamber 72, the low-stage compressor 21A is also air-cooled.

  As described above in detail, the low-stage side gas coolers of the low-stage side refrigerant circuits 6A and 6B are disposed on the upstream side with respect to the refrigerant flow, and the first low-stage side gas coolers 23A and 23B are located on the downstream side. 2, the first air passage 68 and the second air passage 69 that are independently ventilated by the gas cooler blowers 51 and 52 are formed in the refrigerator unit 3. The first low-stage gas coolers 23A and 23B and the high-stage gas coolers 11A and 11B are installed in the first air path 68, and the second low-stage gas coolers 26A and 26B are installed in the second air path 69. Therefore, the second low-stage gas coolers 26 </ b> A and 26 </ b> B located on the downstream side with respect to the refrigerant flow can be effectively air-cooled by the air ventilated through the second air passage 69.

  On the other hand, since the first low-stage gas coolers 23A and 23B located on the upstream side are installed in the first air passage 68 together with the high-stage gas coolers 11A and 11B, the high-stage gas coolers 11A and 11B are installed in the first stage. The size of the refrigerator unit 3 can be reduced as compared with the case where the low-stage gas coolers 23A and 23B are installed in a separate air passage. This is extremely effective particularly when the first and second (plural) low-stage refrigerant circuits 6A and 6B are provided as in the embodiment.

  In this case, the first low-stage gas coolers 23A and 23B are arranged on the downstream side of the air in the first air passage 68 with respect to the high-stage gas coolers 11A and 11B. The high stage side gas coolers 11A and 11B can be initially air-cooled by the ventilated air, and the high stage side gas coolers 11A and 11B can be effectively cooled.

  On the other hand, air that has passed through the high-stage gas coolers 11A and 11B is passed through the first low-stage gas coolers 23A and 23B, but the first low-stage gas coolers 23A and 23B are the second low-stage gas coolers 23A and 23B. Since it is located on the refrigerant upstream side of the gas coolers 26A and 26B, the refrigerant flowing into the second low-stage gas coolers 26A and 26B can be pre-cooled by the first low-stage gas coolers 23A and 23B.

  As a result, the heat exchange efficiency in the gas coolers 11A, 11B, 23A, 23B, 26A, and 26B of the high-stage side refrigerant circuit 4 and the low-stage side refrigerant circuits 6A and 6B as a whole can be significantly improved.

  Further, as the gas cooler blower, first and second gas cooler blowers 51 and 52 are provided, the first gas cooler blower 51 is installed in the first air passage 68, and the second gas cooler blower 52 is installed in the second air cooler. Since the air passages 69 and 69 can be independently ventilated by the gas cooler blowers 51 and 52, the high-stage gas coolers 11A and 11B and the low-stage sides are provided. The gas coolers 23A, 23B, 26A, and 26B can be air-cooled more effectively.

  Furthermore, the inside of the refrigerator unit 3 is divided into an upper machine room 60A and a lower machine room 60B by partition plates 66 and 67, the first air path 68 is set to the lower machine room 60B, and the second air path 69 is set to the upper machine room. Since it is configured as 60A, the installation space for the refrigerator unit 3 can be reduced as compared with the case where the air paths 68 and 69 are arranged in parallel. Furthermore, with this configuration, the high-stage gas coolers 11A and 11B and the first low-stage gas coolers 23A and 23B are installed in the first air passage 68 of the lower machine room 60B, and the second air passage of the upper machine room 60A. Since the second low-stage gas coolers 26A and 26B are installed at 69, the weight distribution in the lower part of the refrigerator unit 3 can be increased, and the stability is improved.

  In this case, the high stage compressor 7 and the low stage compressor 21B are installed in the first storage chamber 71 of the lower machine room 60B, and the first and second cascade heat exchangers 43A and 43B are installed in the upper machine room 60A. Since the compressors 7 and 21B having a large weight are disposed in the lower part of the refrigerator unit 3, the stability is further improved. In particular, although the low-stage compressor 21A is also present in the embodiment, since it is installed in the second storage chamber 72 of the upper machine room 60A, it is more stable than when all of them are arranged in the lower part. Therefore, it is possible to reduce the size of the refrigerator unit 3 while maintaining the performance.

  In the embodiment, the low-stage compressor 21B of the second low-stage refrigerant circuit 6B is installed in the lower first storage chamber 71, and the low-stage compressor of the first low-stage refrigerant circuit 6A is installed. 21A is installed in the upper second storage chamber 72, but the low-stage compressor 21B is installed in the second storage chamber 72, and the low-stage compressor 21A together with the high-stage compressor 7 is the first storage. It may be installed in the chamber 71.

  Further, even when the low stage compressors 21A and 21B and the accumulators 39A and 39B are installed in the lower first storage chamber 71 and the high stage compressor 7 is installed in the upper second storage chamber 72, respectively. Good. Further, in the embodiment, the inside of the machine room 60 is divided up and down by the partition plates 66 and 67. However, the present invention is not limited to this, and the air passages 68, 69 may be configured, and in that case, any two of the compressors 7, 21A, 21B are installed on the base 56, and the rest are installed with a shelf-like installation section above them. You can do it.

  In the embodiment, a single high-stage refrigerant circuit and two low-stage refrigerant circuits are cascade-connected. However, the present invention is not limited to this, and one or three or more low-stage refrigerant circuits are connected to the high-stage side. The present invention is also effective for a refrigeration apparatus cascade-connected to a refrigerant circuit. In the embodiments, the present invention is applied to a refrigeration apparatus that cools a showcase. However, the present invention is not limited thereto, and the present invention is also effective for a refrigeration apparatus that cools a vending machine or the like.

DESCRIPTION OF SYMBOLS 1 Refrigeration apparatus 2 Showcase 3 Refrigerator unit 4 High stage side refrigerant circuit 6A, 6B Low stage side refrigerant circuit 7 High stage side compressor 11A, 11B High stage side gas cooler 13 High stage side expansion valve 16A, 16B High stage side evaporation 21A, 21B Low stage compressor 23A, 23B, 26A, 26B Low stage gas cooler 28A, 28B Supercooling heat exchanger 34A, 34B Low stage expansion valve 36A, 36B Low stage evaporator 43A, 43B Cascade heat exchange Unit 51, 52 Gas cooler blower 56 Base 61 Exterior case 66, 67 Partition plate 68, 69 Air passage

Claims (6)

A high stage side refrigerant circuit including a high stage side compressor, a high stage side gas cooler, a high stage side expansion valve, and a high stage side evaporator;
A low stage side refrigerant circuit including a low stage side compressor, a low stage side gas cooler, a supercooling heat exchanger, a low stage side expansion valve, and a low stage side evaporator;
A cascade heat exchanger configured by the high stage evaporator and the supercooling heat exchanger, evaporating the refrigerant in the high stage evaporator and cooling the refrigerant flowing through the supercooling heat exchanger; Prepared,
In each of the refrigerant circuits, a refrigeration apparatus in which carbon dioxide is sealed as a refrigerant,
The compressor unit, the gas cooler, the cascade heat exchanger, and a refrigerator unit in which a gas cooler blower for air-cooling the gas cooler is installed.
The low-stage gas cooler is composed of a first low-stage gas cooler located on the upstream side with respect to the refrigerant flow and a second low-stage gas cooler located on the downstream side thereof,
A first air path and a second air path that are ventilated by the gas cooler blower are configured in the refrigerator unit,
The refrigeration characterized in that the first low-stage gas cooler and the high-stage gas cooler are installed in the first air passage, and the second low-stage gas cooler is installed in the second air passage. apparatus.   The refrigeration apparatus according to claim 1, wherein the first low-stage gas cooler is disposed on the air downstream side in the first air passage with respect to the high-stage gas cooler. Comprising the first and second gas cooler blowers,
The first gas cooler blower is installed in the first air passage, and the second gas cooler blower is installed in the second air passage. Refrigeration equipment. A partition plate that partitions the inside of the refrigerator unit into an upper machine room and a lower machine room,
The refrigeration apparatus according to any one of claims 1 to 3, wherein the first air passage is configured in the lower machine chamber and the second air passage is configured in the upper machine chamber.   The refrigeration apparatus according to claim 4, wherein each of the compressors is installed in the lower machine room, and the cascade heat exchanger is installed in the upper machine room. The first and second low-stage refrigerant circuits, and the first and second cascade heat exchangers respectively provided in the low-stage refrigerant circuits,
Any two of the high-stage compressor of the high-stage refrigerant circuit and the low-stage compressor of each low-stage refrigerant circuit are installed in the lower machine room, and one is installed in the upper machine room The refrigeration apparatus according to claim 5, wherein the refrigeration apparatus is installed.

Images