JP4258425B2 - Refrigeration and air conditioning equipment - Google Patents

Description

  The present invention relates to a refrigeration / air conditioning apparatus that performs air conditioning or the like by circulating a heat medium such as cold / hot water on a load side. In particular, the present invention relates to an apparatus having two or more load-side heat exchangers that supply heat from a heat source to a load and exchanging heat with a load-side heat medium at different refrigerant pressures.

  In this type of conventional refrigeration / air-conditioning apparatus, a two-stage compression single-stage expansion refrigeration cycle is used to generate an air-conditioning heat source with a high-stage evaporator and a refrigeration heat source with a low-stage evaporator. (For example, refer to Patent Document 1). In addition, a technique is known in which the number of compressors is controlled in series with an evaporator provided in each of a plurality of compressors, cold water passing through a condenser, and cooling water in series. (For example, refer to Patent Document 2).

JP 2002-235960 A (pages 1-8, FIGS. 1 to 4) JP-A-5-93550 (pages 1-5, FIGS. 1 to 3)

However, when different loads are handled by the high-stage evaporator and the low-stage evaporator, when the target temperature is different and the target temperature is far away, or each load ratio is extremely biased, either load exists. Even when it is lost, only the heat exchanger connected to the load can be used, and there is a problem that sufficient heat exchange capability cannot be obtained.

In addition, when the heat exchangers provided in each of the plurality of compressors are used in series to save energy, the optimum efficiency cannot be obtained for the combination of the heat source and the load that changes depending on the outside air, and many compressors can be selected by selecting the stage. In the case of providing a work load on the installation site such as a plurality of pipe connections and power supply wiring connections increases.

  An object of the present invention is to solve the above-described problems, and is to obtain a highly efficient and reliable refrigeration / air conditioning apparatus for each load. In addition, a heat source for refrigeration and air conditioning is obtained with high efficiency by cooling or heating the heat medium in stages using a plurality of heat exchangers in one heat source unit.

An object of the present invention is to realize a more efficient operation by cooling and heating a heat medium in stages, by taking out the intermediate temperature heat medium in the middle stage and performing refrigeration and air conditioning. It is another object of the present invention to obtain a highly efficient refrigeration air conditioner that can be handled easily and flexibly according to the load or according to a load change or expansion.

The refrigeration / air-conditioning apparatus according to the present invention sequentially connects a first compressor, an outdoor heat exchanger, a first decompression unit, and a first load-side heat exchanger that performs heat exchange between the refrigerant and the heat medium. performing a first refrigeration cycle for returning the refrigerant discharged from the first compressor to the first compressor, the outdoor heat exchanger, the second pressure reducing means, heat exchange between the refrigerant and the heat medium second load-side heat exchanger, a second compressor are sequentially connected, and a second refrigeration cycle for combining inhaled refrigerant discharged from the second compressor to the first compressor, the A heat medium inlet and a heat medium outlet arranged so that the heat medium flows in the order of the first load side heat exchanger, the second load side heat exchanger, the first load side heat exchanger, and the first A heat medium intermediate outlet through which a part of the heat medium branched from between the two load side heat exchangers and the load side space are arranged. A first indoor unit having one end connected to the heat medium outlet are arranged on the load side space, includes a second indoor unit having one end connected to said load-side medium intermediate outlet, a first The heat medium flowing out of the indoor unit joins the heat medium flowing out of the second indoor unit and flows into the heat medium inlet .

  The present invention also provides a first refrigeration cycle for sequentially connecting a first compressor, an outdoor heat exchanger, an ejector, a first load-side heat exchanger, and a gas-side outflow passage of a gas-liquid separator, and the gas-liquid A liquid side outflow path of the separator, a second pressure reducing means, a second load side heat exchanger, and a suction side of the ejector are sequentially connected to mix refrigerant from the second load side heat exchanger with the ejector. 2 refrigeration cycles, and the load side medium is circulated in series with the first load side heat exchanger and the second load side heat exchanger.

The present invention also provides a first compressor, an outdoor heat exchanger, a first pressure reducing means, a first load-side heat exchanger that performs heat exchange between the refrigerant and the heat medium during cooling operation or simultaneous cooling and heating operation , Are connected sequentially to return the refrigerant discharged from the first compressor to the first compressor, and during the cooling operation , the outdoor heat exchanger, the second decompression means, the refrigerant and the A second load-side heat exchanger that performs heat exchange with the heat medium and a second compressor are sequentially connected, and the refrigerant discharged from the second compressor is sucked into the first compressor and joined. During the heating operation , the refrigerant flow direction of the first refrigeration cycle is switched in the order of the first compressor, the first load-side heat exchanger, the first pressure reducing means, and the outdoor heat exchanger. The first flow path switching means and the second flow path during heating operation or simultaneous cooling / heating operation Second flow path switching means for switching the refrigerant flow direction of the refrigeration cycle in the order of the second compressor, the second load side heat exchanger, and the second pressure reducing means, and the first load side heat exchanger A first indoor unit connected to the second load side heat exchanger and a pipe through which the heat medium circulates, and performs heat exchange between air in the load side space and the heat medium; and a second indoor unit; The heat medium is provided between the first load-side heat exchanger and the second load-side heat exchanger, and is connected in series with the first and second load-side heat exchangers during cooling operation or heating operation. And the entire amount of the heat medium circulates in the first indoor unit, and a part of the heat medium branches and circulates in the second indoor unit. Between the side heat exchanger and the first indoor unit and before In which the heating medium and a flow channel setting means for switching to circulate independently between the second load-side heat exchanger and the second indoor unit.

In the refrigeration / air-conditioning apparatus of the present invention, the load-side heat medium is cooled step by step with each heat exchanger that generates a plurality of different evaporation pressures and condensation pressures, so that more efficient operation can be performed. it can.

  In the present invention, since the first refrigeration cycle and the second refrigeration cycle have the flow path switching means, the heating medium can be heated with high efficiency at two different evaporation temperatures and condensation temperatures. Furthermore, flexible refrigeration and air conditioning such as cooling in the first refrigeration cycle and heating operation in the second refrigeration cycle can be made possible.

  In the present invention, when the heat medium of the load side circuit is cooled or heated in stages, the intermediate temperature heat medium is taken out and the refrigeration air-conditioning is performed, so it can be easily applied to various systems. A highly efficient refrigeration air conditioner that can be obtained.

Embodiment 1 FIG.
FIG. 1 shows an example of the entire configuration of a refrigeration / air-conditioning apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a heat source unit, and 2 is a load side space. The heat source unit 1 includes a high-stage compressor 3 and a low-stage compressor 4 at least one of which can adjust the operation capacity, which are connected in series to form a two-stage compression cycle. 5 is an air heat exchanger, 6 is a blower, and the heat exchange amount in the air heat exchanger 5 is adjusted by the blower 6. Reference numerals 7 and 8 respectively denote a high stage expansion valve and a low stage expansion valve, which are variable throttles so that the heat exchange amounts of the high stage heat exchanger 9 and the low stage heat exchanger 10 can be adjusted. Further, a heat medium inlet port 12 and a heat medium outlet port 13 are arranged so that the load-side heat medium flows in the order of the high stage heat exchanger 9 and the low stage heat exchanger 10, and the high stage heat exchanger 9 and the low stage heat exchanger 9 A flow rate adjustment valve 11 is provided between the stage heat exchanger 10 and a heat medium intermediate outlet port 14 serving as a third heat medium connection port is disposed.

In the load side space 2, a plurality of indoor units 15 (not shown) each having an indoor unit 15 whose one end is connected to the heat medium outlet 13 and an indoor unit 16 whose one end is connected to the heat medium intermediate outlet 14 are installed. The other ends of these indoor units 15 and 16 are connected to a heat medium transport pump 17 and are configured so that the heat medium circulates between the load side space 2 and the heat source unit 1. The working refrigerant of the refrigeration cycle, which is the heat source side of the refrigeration / air conditioning apparatus, is R407C, which is a non-azeotropic refrigerant mixture, and water is used as the heat medium of the load side cycle.

  In the refrigeration / air conditioning apparatus of the first embodiment configured as described above, the cooling operation using only the indoor unit 15 or the cooling operation using both the indoor units 15 and 16 is performed according to the magnitude of the load and the load characteristics. Do.

First, the refrigeration cycle operation in the heat source unit 1 that is the primary circuit will be described with reference to FIGS. 1 and 2. FIG. 2 is a Ph diagram showing the refrigeration cycle operation, in which the horizontal axis represents specific enthalpy [kJ / kg] and the vertical axis represents refrigerant pressure [MPa].

  The high-temperature and high-pressure gas refrigerant (state A) discharged from the compressor 3 dissipates heat to the outside air in the air heat exchanger 5 and condenses to become a high-pressure liquid refrigerant (state B). This high-pressure liquid refrigerant is depressurized to a medium pressure (state C) of about 10 ° C. at the saturation temperature by the high stage expansion valve 7, and is evaporated by exchanging heat with water as the load side medium by the high stage heat exchanger 9. On the other hand, the low-stage expansion valve 8 is decompressed to a low pressure (state E) of about 5 ° C. at the saturation temperature, and evaporates by exchanging heat with water by the low-stage heat exchanger 10. This low-pressure gas refrigerant (state F) is boosted to medium pressure by the low-stage compressor 4 and merges with the medium-pressure two-phase refrigerant (state D) that has flowed out of the high-stage heat exchanger to medium-pressure saturated gas (state H). Then, it is sucked into the high stage compressor 3 again. As described above, the heat source unit 1 forms a two-stage compression / di-evaporation temperature cycle. This refrigeration cycle operation is the same when both the indoor unit 15 and the indoor unit 15 and 16 are used for cooling.

  Next, the secondary side circuit that is the load side cycle will be described. First, the load side operation when only the indoor unit 15 is used will be described. On the load side, after processing the air conditioning load, water at about 17 ° C. sent from the heat medium transport pump 17 returns to the heat source unit 1 from the heat medium inlet port 12, and the high-stage heat that is the first load side heat exchanger It flows into the exchanger 9. Here, heat exchange is performed with a medium pressure refrigerant at a saturation temperature of 10 ° C., and it flows out as cold water of about 12 ° C. The flow control valve 11 has a flow path set to flow into the 100% low-stage heat exchanger 10, and 12 ° C. cold water is mixed with 5 ° C. refrigerant in the low-stage heat exchanger 10, which is the second load-side heat exchanger. Heat exchange is performed, and the water becomes cold water of about 7 ° C. and exits the heat medium outlet port 13. The 7 ° C. cold water exchanges heat with the air in the load-side space 2 in the indoor unit 15, and again becomes 17 ° C. water and is sucked into the heat medium transport pump 17.

  As the control operation of the refrigeration cycle at this time, the water temperature flowing out of the high stage heat exchanger 9 has a target temperature (for example, 7 ° C.) flowing out of the heat medium outlet port 13 and a water temperature flowing in from the heat medium inlet port 12 ( For example, the capacity ratio of each of the high stage compressor 3 and the low stage compressor 4 is controlled so as to be an intermediate temperature of 17 ° C., and heat exchange processing is performed in each load side heat exchanger. The coefficient of performance is maximized with such a capacity ratio.

  As described above, in the cooling operation in the indoor unit 15, the evaporating pressure of the refrigerant flowing through the high stage heat exchanger 9 (about half of the total refrigerant circulation amount) generates 7 ° C. cold water at a saturation temperature of about 10 ° C. Therefore, the refrigeration cycle coefficient of performance corresponding to the evaporating pressure side refrigerant flow rate at the saturation temperature of about 10 ° C. is more efficient than the operation at the saturation temperature of 5 ° C., and energy-saving cooling operation is possible.

  When the cooling load is smaller than the indoor unit capacity, the transfer flow rate of the heat medium transfer pump 17 can be reduced, and the heat medium temperature after the air conditioning load process can be controlled to a temperature higher than 17 ° C. By doing in this way, it becomes possible to produce | generate cold water of 7 degreeC with the saturation temperature of high stage side evaporation pressure still higher than 10 degreeC, and much more efficient operation is attained.

  At this time, since the pressure increase width of each of the high-stage compressor 3 and the low-stage compressor 4 is smaller than that when the pressure is increased by one compressor, the volume efficiency and the mechanical efficiency are improved, and a highly efficient cooling operation is possible. It becomes. That is, since the compressor input is proportional to the high-low pressure difference * volume flow rate, a higher low pressure is advantageous to obtain the same refrigeration capacity. If the low pressure is low, the density is small and the volume flow is large even at the same mass flow rate, and the efficiency is deteriorated.

  Next, the cooling operation using both the indoor units 15 and 16 that are loads of the present invention will be described. Water of about 17 ° C. sent from the heat medium transport pump 17 returns to the heat source unit 1 from the heat medium inlet port 12 and flows into the high stage heat exchanger 9. Here, heat exchange is performed with a medium pressure refrigerant at a saturation temperature of 10 ° C., and it flows out as cold water of about 12 ° C. In the flow rate adjusting valve 11, a flow path is set so that a predetermined amount is circulated through the indoor unit 16 at a ratio corresponding to the load characteristics, and the remainder flows into the low-stage heat exchanger 10. The 12 ° C. cold water divided into the indoor unit 16 exchanges heat with the air in the load side space 2 to treat the air conditioning load, and the 12 ° C. cold water divided into the low stage heat exchanger 10 is a 5 ° C. refrigerant. The heat exchange is performed, and the water becomes cold water of about 7 ° C. and exits the heat medium outlet port 13. The 7 ° C. cold water exchanges heat with the air in the load-side space 2 in the indoor unit 15, joins the water that has flowed out of the indoor unit 16, and is sucked into the heat medium transport pump 17 again.

  As the control operation of the refrigeration cycle at this time, the target water temperature that flows out of the high-stage heat exchanger 9 and the target water temperature that flows out of the heat medium outlet port 13 depend on the required capacities of the indoor units 15 and 16 connected thereto, respectively. Is set. The capacity ratios of the high stage compressor 3 and the low stage compressor 4 are controlled according to the respective target water temperatures.

  The load characteristics will be explained. Here, the indoor unit 16 performs, for example, outside air processing, and the air to be exchanged with heat is higher than the room temperature. Therefore, a predetermined heat exchange amount is obtained at a cold water temperature higher than the indoor unit 15 to exchange heat with the room air. It is configured to be obtained.

  Alternatively, the indoor unit 16 is also arranged so as to exchange heat with the indoor air in the same manner as the indoor unit 15, and when the cooling load is small, the flow dividing means 11 is a flow rate adjusting valve so as to increase the load ratio processed by the indoor unit 16. The heat medium flow rate ratio may be adjusted at.

  Alternatively, the air in the load side space 2 may be allowed to pass through the indoor unit 15 after passing through the indoor unit 16. With such a configuration, since the indoor heat load is processed by the indoor unit 15 after the indoor heat load is processed by the indoor unit 16, the amount of heat processed by the indoor unit 15 is further reduced and the heat medium is cooled to 7 ° C. The flow rate can be reduced.

  As described above, in the indoor unit 16, since the cooling load is treated with the cold water of 10 ° C. to 15 ° C. cooled to the intermediate temperature by the high stage heat exchanger 9, the flow rate of the heat medium to be cooled to 7 ° C. can be reduced. it can. This means that when viewed from the refrigeration cycle side, the refrigerant flow rate ratio at a high evaporation pressure increases, and a more efficient operation is possible than when the entire amount of the heat medium is cooled to 7 ° C.

That is, in this refrigeration / air-conditioning apparatus, the heat medium is cooled at two evaporation pressures of a saturation temperature of 5 ° C. and a saturation temperature of 10 ° C. or more, so the coefficient of performance is higher than that of all the refrigerants at the evaporation temperature of the saturation temperature of 5 ° C. Get higher. Furthermore, since it became possible to process the load of the load side space 2 directly using a heat medium cooled at an evaporation pressure of a saturation temperature of 10 ° C. or higher,
The refrigerant flow rate ratio at which the evaporation pressure becomes a saturation temperature of 10 ° C. or higher can be increased.

  The refrigeration / air-conditioning apparatus according to the present invention includes a first refrigeration cycle in which a first compressor, an outdoor heat exchanger, a first pressure reducing means, and a first load-side heat exchanger are sequentially connected, and an outdoor A heat exchanger, a second pressure reducing means, a second load side heat exchanger, and a second compressor are connected in order, and a second compressor discharge is joined to the first compressor suction. A multi-stage compressor having a refrigeration cycle and joining the second compressor discharge to the first compressor suction is used, and the load-side heat exchanger is connected in series so that the load-side medium is the first The load side heat exchanger and the second load side heat exchanger are circulated in series in this order. As a result, the refrigeration capacity corresponding to the load can be met by selecting the capacity of the multistage compressor, that is, the rotational speed. The selection of the heat medium corresponding to each of the plurality of loads as the secondary circuit can be performed by adjusting the opening degree of the expansion valves 7 and 8. The opening degree of the expansion valves 7 and 8 can adjust not only the temperature state of the heat medium but also the load side heat exchanger refrigerant outlet state of the primary circuit. In addition, if the individual capacity of each compressor and the heat exchange capacity of each load-side heat exchanger, that is, the heat exchange area is approximately the same, it is not only effective at the partial load but also the refrigeration air conditioner Can be easily installed, arranged, etc., and can be flexibly handled by increasing / decreasing the load or combining with a special load. However, the adjustment of the opening degree of the expansion valves 7 and 8 can cover the difference in the capacity of the compressor and the area of the load side heat exchanger, and a configuration considering efficiency measures may be selected. Further, all the compressors are driven at a constant speed by, for example, induction motor driving, that is, the rotational speed need not be variable. In this case, the load capacity can be changed by adjusting the amount of the heat medium circulating in the secondary circuit such as the pump 17 or stopping some of the plurality of compressors.

  FIG. 3 shows the configuration of another refrigeration / air-conditioning apparatus of the present invention. FIG. 4 is a Ph diagram showing the operation of this other refrigeration cycle. The same or corresponding parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 3, 18 is an ejector. It has a variable throttle mechanism, and further has a function of sucking a refrigerant having a pressure lower than the refrigerant pressure after depressurization by expansion power at the time of depressurization. Reference numeral 19 denotes a gas-liquid separator, which has a function of separating the two-phase refrigerant flowing into the liquid and gas by gravity and allowing the two-phase refrigerant to flow out from the respective outlets. The ejector introduces the high-pressure liquid refrigerant B to the needle part that is moved by the electromagnetic coil, and decompresses and expands it at the nozzle part that performs pressure reduction. At this time, the low-pressure gas refrigerant F is sucked from the surroundings and mixed to form a gas-liquid two-phase refrigerant C. It is. The ejector boosts the low-pressure gas F to the medium pressure by the expansion power when the high-pressure liquid state B is decompressed to the medium-pressure two-phase state C.

  The operation of this refrigeration cycle will be described with reference to FIG. 3 and FIG. The high-temperature and high-pressure gas refrigerant (state A) discharged from the compressor 3 dissipates heat to the outside air in the air heat exchanger 5 and condenses to become a high-pressure liquid refrigerant (state B). The high-pressure liquid refrigerant is decompressed by the ejector 18 and sucks the low-pressure gas refrigerant in the state F to a medium pressure (state C) of about 10 ° C. at the saturation temperature. Thereafter, heat is exchanged with water by the high-stage heat exchanger 9 to evaporate to become an intermediate pressure gas-liquid two-phase refrigerant (state D).

This gas-liquid two-phase refrigerant is separated into a liquid refrigerant (state G) and a gas refrigerant (state H) in the gas-liquid separator 19, and the gas refrigerant is sucked into the compressor 3 again with medium pressure. On the other hand, the liquid refrigerant is decompressed to a low pressure (state E) of about 5 ° C. at the saturation temperature by the low stage expansion valve 8, and is evaporated by exchanging heat with water by the low stage heat exchanger 10. The low-pressure gas refrigerant (state F) evaporated here is sucked into the ejector 18 as described above, becomes the state C, and circulates again to the high stage heat exchanger 9. The operation on the load side is the same as in FIG.

  As described above, by using the ejector, two evaporating pressures can be generated even in one compressor, and chilled water can be generated at an evaporating pressure with a saturation temperature higher than the final chilled water temperature. Is possible. Further, in this embodiment, since expansion power is used to generate the low-stage side evaporation pressure, an input for driving the low-stage compressor is unnecessary, and a great energy saving effect is obtained. The functions of the compressor 4 and the high stage expansion valve 7 are performed by an ejector 18 that can adjust the throttle opening using a needle whose position can be changed with respect to the configuration of FIG. The refrigerant flow rate, that is, the refrigeration capacity of the refrigeration cycle is determined by the rotational speed of the compressor 3, and the ratio of the heat exchange amount between the high stage heat exchanger 9 and the low stage heat exchanger 10 is determined by the throttle opening of the ejector. The expansion valve 8 determines the amount of heat exchange of the low stage heat exchanger 10 and the refrigerant outlet state of the low stage heat exchanger 10.

  Here, the principle of high efficiency in the present invention will be described in detail with reference to FIG. FIG. 5A shows the operation of a conventional refrigeration / air-conditioning apparatus when the cooling operation is performed with one evaporating pressure. However, the load-side heat exchangers 9 and 10 are provided in series, and water as the load-side medium sequentially flows through both heat exchangers, but heat is not exchanged in the second load-side heat exchanger. FIG. 5B illustrates the operation of the present invention for generating two evaporation pressures, and shows a case where the operation is performed only with the indoor unit 15. FIG. 5C and FIG. 5D are operations when both indoor units 15 and 16 are used. FIG. 5E is a Ph diagram illustrating the operation of the refrigeration cycle having two evaporation pressures. In FIG. 5 (e), Gr 1 indicates the refrigerant flow rate through the low stage heat exchanger 10, and Gr 2 indicates the refrigerant flow rate through the high stage heat exchanger 9. W1 represents the input of the low-stage compressor 4, and W2 represents the input of the high-stage compressor 3. These are represented by W1 = Gr1 × Δh1, and W2 = (Gr1 + Gr2) × Δh2, respectively.

  First, FIG. 5A showing the operation of a conventional refrigeration / air-conditioning apparatus will be described. In the refrigeration cycle (not shown), only an evaporation pressure with a saturation temperature of 5 ° C. is generated, and is distributed and evaporated in the high stage heat exchanger 9. Here, the heat medium on the load side is cooled from 17 ° C. to 7 ° C. and circulates in the indoor unit 15. In the indoor unit 15, 27 ° C. air in the load side space 2 is sucked, cooled to 12 ° C. and blown out to the load side space 2 to process the load. In this operation, since it operates only in the refrigeration cycle at the evaporating pressure with a saturation temperature of 5 ° C. shown by the solid line in FIG. 5 (e), the low-stage compressor input W1 = (Gr1 + Gr2) × Δh1 It becomes.

  Next, FIG. 5B will be described. In the refrigeration cycle, an evaporation pressure having a saturation temperature of 5 ° C. and an evaporation pressure having a saturation temperature of 10 ° C. are generated to cool the load-side heat medium. The load-side heat medium is cooled from 17 ° C. to 12 ° C. by the high stage heat exchanger 9 and from 12 ° C. to 7 ° C. by the low stage heat exchanger 10. The flow rate adjusting valve 11 has a flow path on the 100% low stage heat exchanger 10 side, and no heat medium flows through the indoor unit 16. That is, the high-stage heat exchanger 9 and the low-stage heat exchanger 10 have the same heat medium flow rate, the heat medium inlet / outlet temperature difference is the same as 5 [deg], and the heat exchange amount is also equal. Therefore, the refrigerant flow rates Gr1 and Gr2 on the refrigeration cycle side are also substantially equal.

  Since the low-stage compressor input W1 at this time is W1 = Gr1 × Δh1, it is smaller by Gr2 × Δh1 than the above-described FIG. This is the efficiency improvement effect when the two evaporation pressures are used. According to this, it is possible to obtain a greater efficiency improvement effect by increasing the high stage refrigerant flow rate Gr2 as much as possible and by increasing Δh1, that is, by increasing the high stage evaporation pressure.

  As one means for improving the efficiency, a method as shown in FIG. A part of the heat medium that has flowed out of the high-stage heat exchanger 9 is branched by the flow rate adjusting valve 11, is directly circulated from the heat medium intermediate outlet port 14 to the load side space 2, and the load is processed by the indoor unit 16. is there. In FIG. 5 (c), when the ratio of the heat medium flow rate of 12 ° C. indicated by the one-dot chain line to the total heat medium flow rate becomes large, the heat exchange amount in the high stage heat exchanger 9 is the low stage heat exchanger 10. The amount of heat exchange becomes larger, and Gr2 becomes larger on the refrigeration cycle side. Therefore, increasing the heat medium flow rate of 12 ° C. leads to an improvement in efficiency.

On the other hand, in the load side space 2, the blown air temperature is about 17 ° C. in the indoor unit 16. When the cooling load generated in the load side space 2 is relatively large, for example, in the daytime in summer or when the dehumidification load is large, it is essential to treat the load with a heat medium having a blown air temperature of 12 ° C., that is, 7 ° C. Even when there is a relatively small cooling load such as in the middle period or after the evening, the load can often be processed with a heat medium of 12 ° C. even at a blown air temperature of 17 ° C. The embodiment of the present invention is very effective under such a load condition. Under load conditions that allow load treatment even when the blown air temperature is 17 ° C. or higher, control is performed such that the intermediate heat medium temperature is 12 ° C. or higher, that is, the saturation temperature of the high stage evaporation pressure is higher than 10 ° C. With this, it is possible to increase the efficiency further.

  Furthermore, as a configuration for increasing the refrigerant flow rate Gr2 flowing through the high stage heat exchanger 9, for example, a method as shown in FIG. In FIG. 5D, in the load side space 2, 27 ° C. air is cooled to 17 ° C. by the indoor unit 16 and then cooled to 12 ° C. by the indoor unit 15. In such a configuration, the operation for cooling the air temperature from 27 ° C. to 17 ° C. in the indoor unit 16 is the same as that in FIG. 5C, but the air temperature in the indoor unit 15 can be cooled from 17 ° C. to 12 ° C. In FIG. 5 (c), the heat exchange amount becomes small while cooling from 27 ° C. to 12 ° C. This means that the ratio of the amount of heat processed by the indoor unit 15 to the amount of heat processed by the indoor unit 16 is reduced compared to the operation of FIG. 5 (c). It shows that the flow rate ratio of Gr2 increases with respect to the stage refrigerant flow rate Gr1.

  Thus, in the configuration in which two evaporation pressures are generated and each has an independent heat exchanger, increasing the high-stage side refrigerant flow rate ratio and increasing the high-stage side evaporation pressure improve the efficiency. .

  FIG. 6 shows the configuration of another refrigeration / air-conditioning apparatus of the present invention. The same or corresponding parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 6, 20 a and 20 b are four-way valves that switch the refrigerant flow path between cooling and heating, and are arranged in the high-stage compressor 3 and the low-stage compressor 4, respectively. One end of the four-way valve 20 a is connected to the air heat exchanger 5, and the other end is connected to the high stage heat exchanger 9. One end of the four-way valve 20b is connected to the suction pipe of the high stage compressor 3, and the other end is connected to the low stage heat exchanger 10. 21 is a flow path switching means for making the flow direction of the receiver 22 and the high stage expansion valve 7 the same for cooling and heating, and 23a and 23b are also a high stage heat exchanger 9 and a low stage heat exchanger for cooling and heating. The flow path switching means is arranged so that the ten distribution directions are the same. In this embodiment, since the non-azeotropic refrigerant mixture R407C is used as the refrigerant, the temperature rises during the evaporation process and the temperature falls during the condensation process. In the refrigerant having such characteristics, heat exchange performance can be improved by counterflow.

  On the load side, flow rate adjusting valves 11 a and 11 b are arranged in the heat source unit 1, and the flow rate adjusting valve 11 a transfers the heat medium flowing out of the high stage heat exchanger 9 to each of the low stage heat exchanger 10 and the indoor unit 16. The flow rate adjusting valve 11b has a function of selecting the heat medium flowing out of the indoor unit 15 to flow into either the high stage heat exchanger 9 or the low stage heat exchanger 10.

  The heat source unit 1 is provided with four inlet / outlet ports, ie, heat medium inlet ports 12a and 12b and heat medium outlet ports 13a and 13b, so that the heat medium can be circulated independently of the indoor unit 15 and the indoor unit 16, respectively. The heat medium transport pumps 17a and 17b are also arranged so that the heat medium can flow independently.

  First, the operation during the cooling operation will be described as the operation of the refrigeration cycle for the two indoor units arranged in the load side space 2. The cooling operation of the present invention performs substantially the same operation as the configuration of FIG. This will be briefly described with reference to the Ph diagram of FIG. 2 and FIG.

  The high-temperature and high-pressure gas (state A) discharged from the high-stage compressor 3 is radiated to the outside air by the air heat exchanger 3 to become a high-pressure liquid refrigerant (state B). The two-phase refrigerant (state C) that has passed through the receiver 22 and has been depressurized to a medium pressure by the high stage expansion valve 7 flows into the high stage heat exchanger 9 and partly to the low pressure by the low stage expansion valve 8. The pressure is reduced to a low-pressure two-phase refrigerant (state E). The refrigerant flowing into the high stage heat exchanger 9 exchanges heat with the heat medium to become a medium pressure two-phase refrigerant (state D), while the refrigerant flowing into the low stage heat exchanger 10 also exchanges heat with the heat medium to reduce the pressure. It becomes a gas refrigerant (state F). This low-pressure gas refrigerant is pressurized to the medium pressure by the low-stage compressor 4 and enters the state G, and then merges with the refrigerant in the state D to become the medium-pressure gas refrigerant (state H) and is sucked into the high-stage compressor 3 again. Is done.

  Also on the load side, as described with reference to FIG. 1, in the case of cooling only with the indoor unit 15, the flow rate adjusting valve 11 a, so that the heat medium flows in the order of the high stage heat exchanger 9 and the low stage heat exchanger 10. 11b sets the flow path. When both the indoor units 15 and 16 are cooled, the flow rate adjusting valve 11a diverts the intermediate temperature heat medium flowing out of the high stage heat exchanger 9 to the indoor unit 15 and the low stage heat exchanger 10. The heat medium cooled to a low temperature by the low stage heat exchanger 10 is subjected to the cooling load by the indoor unit 15, and then merged with the heat medium that has been processed the cooling load by the indoor unit 16, and again to the high stage heat exchanger 9. And flows in.

  Next, the operation during the heating operation will be described with reference to FIGS. 6 and 7 in the operation of the refrigeration cycle during the heating operation. FIG. 7 is a Ph diagram showing the refrigeration cycle operation during the heating operation in the configuration of FIG. Moreover, in FIG. 6, the flow path is set in the direction of the broken line in both the four-way valves 20a and 20b.

  The medium pressure gas refrigerant (state A) of about 40 ° C. to 45 ° C. at the saturation temperature discharged from the high stage compressor 3 passes through the flow path switching means 23a and flows into the high stage heat exchanger 9, Heat exchange and condensation (state D). At this time, the temperature is raised to 35 ° C. to 40 ° C. on the heat medium side. On the other hand, in the low-stage compressor 4, a higher pressure than the high-stage compressor 3, for example, a high-pressure gas refrigerant (state G) whose pressure is increased to about 50 ° C. at the saturation temperature is discharged and passes through the flow path switching unit 23b. Into the low-stage heat exchanger 10. The high-pressure liquid refrigerant (state F) condensed by exchanging heat with the heat medium in the low-stage heat exchanger 10 is reduced to an intermediate pressure by the low-stage expansion valve 8 and merged with the intermediate-pressure refrigerant in the state D. It becomes a liquid refrigerant (state C). The heat medium here is heated to about 45 ° C. This medium-pressure liquid refrigerant is reduced in pressure by the high stage expansion valve 7 after passing through the receiver 22 to become a low-pressure two-phase refrigerant (state B). Further, the air heat exchanger 5 absorbs heat from outside air and evaporates to become a low-pressure gas refrigerant (state H), and is sucked again into both the high-stage compressor 3 and the low-stage compressor 4.

  On the load side, switching is performed between the heating mode using only the indoor unit 15 and the heating mode using both the indoor units 15 and 16 by switching the flow path in the same manner as in the cooling operation.

  As described above, in the heating operation with only the indoor unit 15, the heat medium in which the condensation pressure of the refrigerant (about half of the total refrigerant circulation amount) flowing through the high stage heat exchanger 9 is about 40 ° C. and 45 ° C. Therefore, the coefficient of performance of the refrigeration cycle in this part is more efficient than the operation at the saturation temperature of 50 ° C., and energy-saving heating operation is possible.

  Furthermore, when the indoor unit 16 is used, since the heating load is directly treated with the heat medium of 35 ° C. to 40 ° C. heated to the intermediate temperature by the high stage heat exchanger 9, the heat medium flow rate heated to 45 ° C. Can be reduced. This means that when viewed from the refrigeration cycle side, the refrigerant flow rate ratio at a low condensing temperature increases, which is higher than when the entire heat medium is heated to 45 ° C., that is, when heating operation is performed only by the indoor unit 15. Efficient operation is possible.

  Of course, when the load can be processed in the indoor unit 16 at a lower heat medium temperature, the intermediate pressure saturation temperature can be further reduced, and a more efficient heating operation can be performed.

  Moreover, by circulating the air after passing through the indoor unit 16 to the indoor unit 15, the heat exchange amount in the indoor unit 15, that is, the flow rate of hot water heated at the saturation temperature of 50 ° C. can be reduced, More efficient heating operation becomes possible.

  Further, the operation of the simultaneous cooling and heating operation will be described with reference to FIGS. 6 and 8 in the operation of the refrigeration cycle during the simultaneous cooling and heating operation. FIG. 8 is a Ph diagram showing the refrigeration cycle operation during the simultaneous cooling and heating operation of the configuration of FIG. In FIG. 6, the four-way valve 20a has a flow path in the solid line direction, and 20b has a flow path in the broken line direction.

  The medium-pressure gas refrigerant (state A) discharged from the high stage compressor 3 flows into the air heat exchanger 5 and is condensed by exchanging heat with the outside air. This medium-pressure liquid refrigerant (state B) passes through the flow path switching means 21 and the receiver 22 and is decompressed to a low pressure by the high stage expansion valve 7. On the other hand, in the low stage compressor 4, high-pressure gas refrigerant (state G) whose pressure has been increased to about 50 ° C. at the saturation temperature is discharged, and flows into the low stage heat exchanger 10 through the flow path switching unit 23b. The high pressure liquid refrigerant (state F) condensed by exchanging heat with the heat medium in the low stage heat exchanger 10 is decompressed to a low pressure by the low stage expansion valve 8 and merged with the refrigerant decompressed by the high stage expansion valve, It becomes a low-pressure two-phase refrigerant (state C). The low-pressure two-phase refrigerant passes through the flow path switching unit 23a and flows into the high stage heat exchanger 9, and is evaporated by exchanging heat with the heat medium. This low-pressure gas refrigerant (state H) is again sucked into both the high-stage compressor 3 and the low-stage compressor 4.

  On the load side, independent heat medium flow paths are formed by the flow rate adjusting valves 11a and 11b. That is, the flow rate adjusting valve 11a guides the heat medium flowing from the high stage heat exchanger 9 to the 100% heat medium outlet port 13a, and the flow rate adjusting valve 11b converts the heat medium flowing from the heat medium inlet port 12b to 100% low stage heat. Guide to exchanger 10.

  As described above, the air heat exchanger 5 and the low-stage heat exchanger 10 function as a condenser, the high-stage heat exchanger 9 functions as an evaporator, and the heat medium flow path is low with the high-stage heat exchanger 9. By switching so that each of the stage heat exchangers 10 circulates independently, it is possible to perform a cooling and heating simultaneous operation such as a heating operation in the indoor unit 15 and a cooling operation in the indoor unit 16.

  At this time, the condensation heat obtained by the low stage heat exchanger 10 uses the cooling load processed by the high stage heat exchanger 9 as a heat source, and the operation efficiency when the simultaneous cooling and heating load is mixed is greatly improved.

  In contrast to the above description in the configuration of FIG. 6, the flow operation of the load-side heat medium will be specifically described with reference to FIG. FIG. 9 (a) shows a configuration in the case of operation with only the indoor unit 15, and the flow rate adjusting valves 11a and 11b have the load side heat exchangers 9 and 10 so that the water as the heat medium becomes the flow shown in the figure. Are opened and closed in series so that the flow rate adjusting valve 11a is not diverted to the indoor unit 16. FIG. 9 (b) shows the configuration in the operation state in both the indoor units 15 and 16, and the flow rate adjusting valves 11a and 11b are load-side heat exchangers so that water as a heat medium has a flow shown in the figure. 9 and 10 are flown in series, and the flow rate adjusting valve 11a is diverted to the indoor unit 16 to perform opening and closing to flow to both loads. For the above configuration, a pump for circulating water as a heat medium may be provided corresponding to each load as shown in FIG. 6, or only one pump may be provided at a position where it can be circulated to both loads. Is also clear from the figure. FIG. 9C shows an example in which both loads are operated independently. For example, an operation state in which cooling and heating are simultaneously performed in each indoor unit is shown. From the primary cycle on the heat source side to the load side heat exchanger 9. 10 shows a configuration in which water that is a load-side heat medium becomes hot water and cold water because of the hot and cold heat supplied to 10, and the secondary circuit is completely separated according to the demand of the load. As shown in the figure, the pump 17 is provided according to each load, and opens and closes the flow rate adjusting valves 11a and 11b that make the load circuit independent.

  Although the example which uses hydrofluorocarbon as a heat source side refrigerant | coolant and the example which circulates water as a load side heat medium was shown in the above description, all are not limited to this. For example, a natural refrigerant such as carbon dioxide may be used on the primary side and the secondary side, or a plurality of types may be mixed. In order to operate the refrigeration and air-conditioning apparatus of the present invention with high efficiency, the variable speed compressor 3 or 4, the expansion valves 7 and 8, the flow rate adjustment valve 11, and the amount of water that can adjust the opening degree of the high stage side and the low stage side. Although an explanation has been given of using the adjustable pump 17 and adjusting each according to the type of load and the load capacity, each adjusting device is not necessarily required. It is possible to use any one of the devices set in advance according to the load without any adjustment, or to adjust only one of them. Instead of the compressor 3, the pump 17, and the expansion valve at a substantially constant speed by an induction machine or the like. Even if the expansion means 7 and 8 in a fixed state and the on-off valve 11 that does not adjust the flow rate are used, higher efficiency can be obtained than in the conventional apparatus.

  As described above, the refrigeration / air-conditioning apparatus according to the embodiment of the present invention has a high stage heat exchanger 9 and a low stage heat exchanger in the cooling operation, similar to those shown in FIGS. By making the evaporation pressure of 10 different and cooling the heat medium in stages, a highly efficient cooling operation is possible.

  Further, during the heating operation, the condensation pressures of the high stage heat exchanger 9 and the low stage heat exchanger 10 are different from each other, and the heat medium is heated stepwise so that the compression ratio in the high stage compressor 3 is increased. It can be made small, and highly efficient operation is possible.

  Further, at the time of simultaneous cooling and heating operation, since the cooling load processed by the high stage heat exchanger 9 can be used as a heating heat source, highly efficient operation is possible. Here, cooling and heating have been described as examples, but one may be an air conditioning load for cooling or dehumidification, and the other may utilize condensation heat such as hot water supply.

  The refrigeration / air-conditioning apparatus according to the present invention includes a first refrigeration cycle in which a first compressor, an outdoor heat exchanger, a first pressure reducing unit, and a first load-side heat exchanger are sequentially connected; An outdoor heat exchanger, a second pressure reducing means, a second load side heat exchanger, and a second compressor are connected in order, and the discharge of the second compressor is merged with the suction of the first compressor. A second refrigeration cycle is provided, and the load-side medium is circulated in series in the order of the first load-side heat exchanger and the second load-side heat exchanger.

  Alternatively, the first compressor, the outdoor heat exchanger, the ejector, the first load-side heat exchanger, the first refrigeration cycle formed by sequentially connecting the gas-side outflow passages of the gas-liquid separator, and the gas-liquid separation A liquid side outflow path, a second decompression means, a second load side heat exchanger, a second refrigeration cycle joined to the ejector, and a load side medium for the first load side heat exchange And the second load-side heat exchanger in series in this order.

  Alternatively, the first flow path switching means for switching the refrigerant flow direction of the first refrigeration cycle in the order of the first compressor, the first load side heat exchanger, the first pressure reducing means, and the outdoor heat exchanger. And a second flow path switching means for switching the refrigerant flow direction of the second refrigeration cycle in the order of the second compressor, the second load-side heat exchanger, and the second pressure reducing means. A heat source for air conditioning is obtained with high efficiency by cooling or heating the heat medium in stages using a plurality of heat exchangers in the heat source unit.

In the present invention, when the heat medium is cooled or heated stepwise, the heat medium having an intermediate temperature in the middle of the heat medium is taken out and air-conditioned, thereby realizing a more efficient operation.

  In the refrigeration / air-conditioning apparatus according to the present invention, two different evaporation pressures are generated by one heat source unit, and the load-side heat medium is cooled step by step by each heat exchanger. Higher efficiency operation than cooling is possible. In the present invention, the heat exchange amount of the first load side heat exchanger, the load side medium amount, and the like are made larger than those of the second load side heat exchanger. High efficiency is obtained by changing the rotation speed of the compressor. Further, the amount of refrigerant circulating through the first refrigeration cycle is made larger than the amount of refrigerant circulating through the second refrigeration cycle. Higher efficiency is achieved by changing the flow rate ratio between the high and low stages by operating the rotation speed of the compressor. For this reason, the first compressor and the second compressor, or both the first compressor and the ejector are independently set to variable speeds. In addition, efficient operation is performed by changing the throttles of the expansion valves of both refrigeration cycles. However, depending on the operating range and application, one may be fixed to a fixed value set in advance.

  Further, the expansion power is recovered by the ejector, and the compressor is sucked into the compressor at a pressure higher than the low-stage evaporation pressure, so that a more efficient operation can be performed.

  In addition, since the first refrigeration cycle and the second refrigeration cycle each have the flow path switching unit, the heating medium can be heated with high efficiency at two different condensation temperatures. Furthermore, it is possible to simultaneously perform cooling in the first refrigeration cycle and heating operation in the second refrigeration cycle.

  In the above description, the air conditioner is mainly taken as an example, but it can also be used for a refrigerator or a refrigerator having a difference in cooling temperature, or a combination of air conditioning and freezing. In the combined use, it is possible to easily cope with increasing or decreasing a specific load by changing the control contents, recombining the circuit, changing the load-side heat exchanger, or the like.

  In particular, if the first and second refrigeration cycles in the configurations of FIGS. 1 and 3 are used in a home refrigerator, a refrigeration air conditioner that is always efficient even when the storage room is switched or the load is large or small can be obtained. What is necessary is just to supply the air which circulates the inside as it is to a 1st load side heat exchanger and a 2nd load side heat exchanger as a series load. That is, instead of the aqueous medium as shown in FIGS. 1 and 3, the heat of the air circulating in the refrigerator by the internal fan becomes a load. As shown in FIG. 3, it is possible to use a single compressor and use an ejector, and the low-stage expansion means can be a capillary tube and can be constructed inexpensively. The air heat exchanger 5 in FIG. 3 may be a condenser provided on the wall surface of the refrigerator, and in that case, the blower 6 is also unnecessary.

1 is an overall configuration diagram of a refrigeration / air conditioning apparatus showing Embodiment 1 of the present invention. FIG. It is a Ph diagram which shows the refrigerating cycle operation | movement of Embodiment 1 of this invention. It is a whole block diagram of another freezing and air-conditioning apparatus of this invention. It is a Ph diagram which shows another refrigeration cycle operation | movement of this invention. It is explanatory drawing of the efficiency improvement effect of this invention. It is a block diagram of another freezing and air-conditioning apparatus of this invention. It is a Ph diagram which shows the refrigerating cycle operation | movement at the time of the heating operation of another refrigerating cycle of this invention. It is a Ph diagram which shows the refrigerating-cycle operation | movement at the time of simultaneous cooling-heating operation of another refrigerating cycle of this invention. It is a figure which shows the distribution | circulation operation | movement of the load side heat carrier of another refrigeration cycle of this invention.

Explanation of symbols

1 heat source unit, 2 load side space,
3 High stage compressor, 4 Low stage compressor,
5 Air heat exchanger, 6 Blower,
7 High stage expansion valve, 8 Low stage expansion valve,
9 High stage heat exchanger, 10 Low stage heat exchanger,
11a, 11b Flow rate regulating valve, 12a, 12b Heat medium inlet port,
13a, 13b Heat medium outlet port, 14 Heat medium intermediate outlet port,
15, 16 indoor unit, 17a, 17b heat transfer pump,
18 Ejector, 19 Gas-liquid separator,
20a, 20b four-way valve, 21 flow path switching means,
22 Receiver, 23a, 23b Flow path switching means.

Claims (7)

The first compressor, the outdoor heat exchanger, the first pressure reducing means, and the first load-side heat exchanger that performs heat exchange between the refrigerant and the heat medium were sequentially connected and discharged from the first compressor. A first refrigeration cycle for returning the refrigerant to the first compressor;
The outdoor heat exchanger, the second pressure reducing means, the second load side heat exchanger for exchanging heat between the refrigerant and the heat medium, and the second compressor are sequentially connected and discharged from the second compressor. A second refrigeration cycle in which the first refrigerant is sucked into the first compressor and merged;
A heat medium inlet and a heat medium outlet arranged so that the heat medium flows in the order of the first load side heat exchanger and the second load side heat exchanger;
A heat medium intermediate outlet through which a part of the heat medium branched from between the first load side heat exchanger and the second load side heat exchanger flows out;
A first indoor unit disposed in the load side space, one end of which is connected to the heat medium outlet;
A second indoor unit disposed in the load side space, one end of which is connected to the load side medium intermediate outlet,
The refrigeration / air conditioning apparatus , wherein the heat medium flowing out of the first indoor unit merges with the heat medium flowing out of the second indoor unit and flows into the heat medium inlet . A flow rate adjustment valve provided between the first load-side heat exchanger and the second load-side heat exchanger, for branching a part of the heat medium flowing out from the first load-side heat exchanger When,
And a load-side medium transport pump configured to connect the other ends of the first and second indoor units and to circulate the heat medium through the first and second load-side heat exchangers. The refrigeration / air conditioning apparatus according to claim 1 . First flow path switching means for switching the flow direction of the first refrigeration cycle in the order of a first compressor, a first load side heat exchanger, a first pressure reducing means, and an outdoor heat exchanger; And a second flow path switching means for switching the refrigerant flow direction of the second refrigeration cycle in the order of the second compressor, the second load-side heat exchanger, and the second pressure reducing means. The refrigeration / air conditioning apparatus according to claim 1 or 2 . The refrigeration according to any one of claims 1 to 3, wherein air in the load side space is configured to pass through the first indoor unit and then through the second indoor unit.・ Air conditioning equipment. During cooling operation or simultaneous cooling and heating operation, the first compressor, the outdoor heat exchanger, the first pressure reducing means, and the first load-side heat exchanger that performs heat exchange between the refrigerant and the heat medium are sequentially connected to each other. A first refrigeration cycle for returning refrigerant discharged from one compressor to the first compressor;
During the cooling operation, the outdoor heat exchanger, the second pressure reducing means, a second load side heat exchanger for exchanging heat between the refrigerant and the heat medium, and a second compressor are sequentially connected, and the second heat exchanger is connected. A second refrigeration cycle for sucking and joining the refrigerant discharged from the compressor into the first compressor;
First flow path switching means for switching the refrigerant flow direction of the first refrigeration cycle in the order of the first compressor, the first load side heat exchanger, the first pressure reducing means, and the outdoor heat exchanger during heating operation. When,
Second flow path switching for switching the refrigerant flow direction of the second refrigeration cycle in the order of the second compressor, the second load-side heat exchanger, and the second pressure reducing means during heating operation or simultaneous cooling and heating operation. Means,
A first chamber that is connected to the first load-side heat exchanger and the second load-side heat exchanger by a pipe through which the heat medium circulates and performs heat exchange between the air in the load-side space and the heat medium. A unit, a second indoor unit,
The heat medium is provided between the first load-side heat exchanger and the second load-side heat exchanger, and the heat medium is connected in series with the first and second load-side heat exchangers during cooling operation or heating operation. The total amount of the heat medium circulates in the first indoor unit, and a part of the heat medium diverges and circulates in the second indoor unit. Flow path setting means for switching the heat medium to circulate independently between the heat exchanger and the first indoor unit and between the second load side heat exchanger and the second indoor unit. And a refrigeration / air-conditioning device. During the heating operation, the refrigerant flow direction from the second switching means is in the order of the second compressor, the second load side heat exchanger, the second pressure reducing means, the first pressure reducing means, and the outdoor heat exchanger. In the simultaneous cooling and heating operation, the refrigerant flow direction from the second switching means is that of the second compressor, the second load side heat exchanger, the second pressure reducing means, and the first load side heat exchanger. 6. The refrigeration / air conditioning apparatus according to claim 5, wherein the refrigeration / air conditioning apparatus is configured to flow in order and to be sucked into both the first and second compressors. The refrigeration / air-conditioning apparatus according to any one of claims 1 to 6, wherein the refrigerant circulating through the first refrigeration cycle and the second refrigeration cycle is a non-azeotropic refrigerant mixture.

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