JP7424425B1 - dual refrigeration equipment - Google Patents

Abstract

An object of the present invention is to provide a binary refrigeration system that can suppress a decrease in heating capacity due to deterioration of the startup operation by quickly performing the startup operation. [Solution] A high-temperature side refrigerant circuit 2 in which high-temperature side refrigerant circulates, a first circulation path 23 in which heat is exchanged with the high-temperature side refrigerant in a cascade heat exchanger 13, and a low-temperature side heat exchanger 24 generate heat. The low source refrigerant circuit 3 includes a second circulation path 26 that exchanges heat with the medium and circulates the low source refrigerant, and the high source heat exchanger 11 exchanges heat with the high source refrigerant to generate low source heat. The heat medium circuit 4 includes a heat medium circuit 4 in which a heat medium that exchanges heat with a low source side refrigerant circulates in an exchanger 24, and a heat medium circuit 4 in which a heat medium circulates between a high source side heat exchanger 11 and a low source side heat exchanger 24. It includes a first heat medium circulation path 35 in which the heat medium circulates, and a second heat medium circulation path 36 in which the heat medium circulates through the high-side heat exchanger 11. [Selection diagram] Figure 1A

Description

The present invention relates to a binary refrigeration system, and particularly to a binary refrigeration system that can suppress a decrease in heating capacity.

A conventional binary refrigeration system includes a high-base refrigerant circuit and a low-base refrigerant circuit, and a cascade heat exchanger (intermediate heat exchanger) that is shared by the high-base refrigerant circuit and the low-base refrigerant circuit. A cascade heat exchanger exchanges heat between the refrigerant circulating in the high-temperature refrigerant circuit and the refrigerant circulating in the low-temperature refrigerant circuit, and the water is heated by the high-temperature refrigerant circulating in the high-temperature refrigerant circuit, producing hot water. is being generated.

In such a binary refrigeration system, there is an imbalance in the time from startup to steady state due to differences in refrigerant characteristics and temperature conditions at startup between the high-power side refrigeration circuit and the low-side refrigeration circuit. This may cause the compressor in the low-source refrigerant circuit to come to a protective stop. Therefore, in the binary refrigeration system disclosed in Patent Document 1, high pressure overflow occurs in the low-side refrigeration circuit during the period from startup of the dual refrigeration system to transition to steady operation (hereinafter referred to as "start-up operation"). In order to prevent protection from stopping due to rising temperatures, the ratio of the rotation speed of the compressor in the high-power side refrigeration circuit to the speed of the compressor in the low-power side refrigeration circuit during start-up operation is set to be larger than the ratio in steady-state operation. .

Japanese Patent Application Publication No. 2013-213590

However, in the binary refrigeration system disclosed in Patent Document 1, the ratio of the rotation speed of the compressor of the high-power side refrigeration circuit to the rotation speed of the compressor of the low-power side refrigeration circuit during start-up operation is lower than the ratio during steady-state operation. Since the rotation speed of the compressor of the low-source side refrigeration circuit is set to be large, the number of rotations during start-up operation of the compressor of the low-source side refrigeration circuit is limited, so there is a problem that it takes time to demonstrate sufficient heating capacity during start-up operation.

In view of the above problems, an object of the present invention is to provide a binary refrigeration system that can suppress a decrease in heating capacity due to rapid start-up operation.

One aspect of the present invention is a high-temperature compressor, a high-temperature heat exchanger, a high-temperature decompression mechanism, and a cascade heat exchanger that are sequentially connected by refrigerant piping, and the high-temperature side refrigerant circulates. The source side refrigerant circuit, the low source side compressor, the cascade heat exchanger, the low source side first pressure reduction mechanism, and the heat source side heat exchanger are sequentially connected by refrigerant piping, and the low source side refrigerant circulates. A first circulation path in which the high-side refrigerant and the low-side refrigerant exchange heat in the cascade heat exchanger; 1. Connect the pressure reduction mechanism and the heat source side heat exchanger with refrigerant piping provided with the low source side heat exchanger and the low source side second pressure reducing mechanism, and connect the low source side compressor and the low source side heat exchanger. A low source side refrigerant circuit comprising a second circulation path in which the exchanger, the low source side second pressure reduction mechanism, and the heat source side heat exchanger are sequentially connected by refrigerant piping, and in which the low source side refrigerant circulates; 1 The circulation pump, the user side heat exchanger, the low source side heat exchanger, and the high source side heat exchanger are connected in sequence with piping to circulate the heat medium, and the high source side heat exchanger A first heat medium circulation path in which a side refrigerant and a heat medium exchange heat, and a low source side refrigerant and a heat medium exchange heat in a low source side heat exchanger, and a user side heat exchange in the first heat medium circulation path. a first bypass path connecting between the heat exchanger and the low-side heat exchanger, and between the low-side heat exchanger and the high-side heat exchanger; A heat medium circuit including an exchanger, a first bypass path, and a second heat medium circulation path in which the heat medium circulates, in which the heat exchanger is connected in sequence with piping, and a cascade heat exchanger. The high source side refrigerant and the low source side refrigerant exchange heat, and in the heat medium circuit, the first heat medium is switched to flow into the first heat medium circulation path or the second heat medium circulation path. This is a two-way refrigeration system that includes a switching means and a control unit that controls a high-base refrigerant circuit, a low-base refrigerant circuit, and a heat medium circuit.

According to the present invention, it is possible to provide a binary refrigeration system that can suppress a decrease in heating capacity due to rapid start-up operation.

1 is a refrigerant circuit diagram of a binary refrigeration device according to an embodiment of the present invention. It is a figure showing the flow of the refrigerant of the 1st mode operation of the binary refrigeration system concerning an embodiment of the present invention. It is a figure showing the flow of the refrigerant in the second mode operation of the binary refrigeration system concerning an embodiment of the present invention. FIG. 1 is a control block diagram of a binary refrigeration system according to an embodiment of the present invention. FIG. 3 is a control flow diagram of the dual refrigeration device according to the embodiment of the present invention. FIG. 3 is a refrigerant circuit diagram of a binary refrigeration device according to another embodiment of the present invention. It is a figure which shows the flow of the refrigerant|coolant in the 1st mode operation of the binary refrigeration apparatus based on other embodiment of this invention. It is a figure which shows the flow of the refrigerant|coolant in the 2nd mode operation of the binary refrigeration apparatus based on other embodiment of this invention. FIG. 3 is a control block diagram of a binary refrigeration device according to another embodiment of the present invention. FIG. 7 is a control flow diagram of a binary refrigeration device according to another embodiment of the present invention.

EMBODIMENT OF THE INVENTION Below, embodiment of the binary refrigeration apparatus based on this invention is described in detail based on drawing. Note that the present invention is not limited to this embodiment.

FIG. 1A is a refrigerant circuit diagram of the binary refrigeration device 1 of this embodiment. FIG. 2 is a control block diagram in the binary refrigeration system 1 of this embodiment.

A binary refrigeration system 1 according to this embodiment will be described with reference to FIGS. 1A to 1C. FIG. 1A is a refrigerant circuit diagram of the binary refrigeration device 1 of this embodiment. The binary refrigeration system 1 is used for cooling operation when the user-side heat exchanger 31 is used as an evaporator, and for operation to produce hot water or when the user-side heat exchanger 31 is used as a condenser. , is a refrigeration device that can be used for heating operation. Hereinafter, the operation for producing hot water and the heating operation may be collectively referred to as the heating operation. In this embodiment, a binary refrigeration system used for heating operation will be described. The binary refrigeration system 1 includes a high-base refrigerant circuit 2, a low-base refrigerant circuit 3, a heat medium circuit 4, and a control section 5. The control section 5 includes a storage means for storing data such as target temperature, control software, etc., and controls the binary refrigeration apparatus 1.

The high end refrigerant circuit 2 includes a high end compressor 10, a high end heat exchanger 11, a high end expansion valve 12 as a high end pressure reduction mechanism, and a cascade heat exchanger 13 in a refrigerant pipe 6. They are connected sequentially, and the high-end refrigerant circulates. In this embodiment, the high source side heat exchanger 11 is a heat exchanger in which the high source side refrigerant and the heat medium flowing through the heat medium circuit 4 exchange heat. The cascade heat exchanger 13 is a heat exchanger in which the high-base refrigerant and the low-base refrigerant flowing through the low-base refrigerant circuit 3 exchange heat. Note that the high-side heat exchanger 11 and the cascade heat exchanger 13 may be, for example, a plate heat exchanger or a double pipe heat exchanger as long as they are heat exchangers that can exchange heat between liquids. Further, in the present embodiment, the high source side heat exchanger 11 is a heat exchanger in which the high source side refrigerant and the heat medium flowing through the heat medium circuit 4 exchange heat. It may be a heat exchanger that exchanges heat with air as a medium. The arrows in the high-base refrigerant circuit 2 indicate the flow of high-base refrigerant during heating operation.

In the high-temperature side refrigerant circuit 2, on the discharge side of the high-temperature side compressor 10, the high-temperature side refrigerant discharged from the high-temperature side compressor 10 is allowed to flow to the high-temperature side heat exchanger 11 side, or A four-way valve 14 on the high side is connected to switch whether or not the water flows to the cascade heat exchanger 13 side. In this embodiment, a case will be described in which the high-base refrigerant discharged from the high-base compressor 10 flows to the high-base heat exchanger 11 side by the high-base four-way valve 14 (heating operation). Therefore, in the high temperature side refrigerant circuit 2, the high temperature side refrigerant discharged from the high temperature side compressor 10 flows through the high temperature side heat exchanger 11, the high temperature side expansion valve 12, and the cascade heat exchanger 13. , is sucked into the high-end compressor 10.

The low-end refrigerant circuit 3 has a first circulation path 23 and a second circulation path 26 . The first circulation path 23 includes a low-base compressor 20, a cascade heat exchanger 13 connected to the high-base refrigerant circuit 2, and a low-base first expansion valve 21 as a first low-base pressure reducing mechanism. , and the heat source side heat exchanger 22 are sequentially connected through refrigerant piping 6, and the low source side refrigerant circulates. The heat source side heat exchanger 22 is a heat exchanger in which the low source side refrigerant and the outside air exchange heat. The heat source side heat exchanger 22 is provided with a condensation temperature detection sensor 22a that measures the condensation temperature of the low-end refrigerant flowing through the heat source side heat exchanger 22. The cascade heat exchanger 13 is a heat exchanger in which the low-base refrigerant and the high-base refrigerant flowing through the high-base refrigerant circuit 2 exchange heat. The cascade heat exchanger 13 includes a condensing temperature detection sensor 13a that measures the condensation temperature (refrigerant condensation temperature) of the low-base refrigerant flowing through the cascade heat exchanger 13, and an outlet temperature detection sensor that measures the outlet temperature of the low-base refrigerant. A sensor 13b is provided. The arrows in the low-base refrigerant circuit 3 indicate the flow of the low-base refrigerant.

The low source side refrigerant circuit 3 connects between the low source side compressor 20 and the cascade heat exchanger 13 and between the low source side first expansion valve 21 and the heat source side heat exchanger 22. The exchanger 24 and the low base side second expansion valve 25 as the low base side second pressure reducing mechanism are connected by a refrigerant pipe provided with the low base side compressor 20, the low base side heat exchanger 24, and the low base side second expansion valve 25 as the low base side second pressure reducing mechanism. The second side expansion valve 25 and the heat source side heat exchanger 22 are sequentially connected by refrigerant piping, and a second circulation path 26 is provided in which the low-source side refrigerant circulates. The low source side heat exchanger 24 is a heat exchanger that has a first heat storage section including a heat storage material, and in which the low source side refrigerant and the heat medium flowing through the heat medium circuit 4 exchange heat. The low source side heat exchanger 24 includes a condensation temperature detection sensor 24a that measures the condensation temperature of the low source side refrigerant flowing through the low source side heat exchanger 24, and an outlet temperature detection sensor that measures the outlet temperature of the low source side refrigerant. 24b is provided. Also provided is a heat medium return temperature detection sensor 24c that measures the heat medium return temperature, which is the temperature at which the heat medium flowing through the heat medium circuit 4 flows into the low source heat exchanger 24. Note that the low-side heat exchanger 24 may be, for example, a plate heat exchanger or a double pipe heat exchanger as long as it is a heat exchanger that can exchange heat between liquids.

In the low-base refrigerant circuit 3, the low-base refrigerant discharged from the low-base compressor 20 is connected to the cascade heat exchanger 13 side and the low-base heat exchanger 20 on the discharge side of the low-base compressor 20. A four-way valve 27 on the low source side is connected to switch whether to flow to the heat source side heat exchanger 22 or the heat source side heat exchanger 22 side. In this embodiment, when the low source side four-way valve 27 causes the low source side refrigerant discharged from the low source side compressor 20 to flow to the cascade heat exchanger 13 side and the low source side heat exchanger 24 side (heating driving). In this case, in the low source side refrigerant circuit 3, the low source side refrigerant discharged from the low source side compressor 20 passes through the cascade heat exchanger 13, the low source side first expansion valve 21, and the heat source side heat exchanger 22. The low-base refrigerant that flows and is sucked into the low-base compressor 20 and discharged from the low-base compressor 20 is passed through the low-base heat exchanger 24, the second low-base expansion valve 25, and the heat source side. It flows through the heat exchanger 22 and is sucked into the low-end compressor 20.

In the low source side refrigerant circuit 3, the low source side compressor 20, the heat source side heat exchanger 22, and the low source side four-way valve 27 are configured to be used in common in the first circulation path 23 and the second circulation path 26.

In the heat medium circuit 4, a first circulation pump 30, a usage side heat exchanger 31, a low source side heat exchanger 24, and a high source side heat exchanger 11 are sequentially connected via piping 32, and a heat exchanger 31 is connected to the heat exchanger 31 as a heat refrigerant. Water circulates. Note that antifreeze may be used instead of water as the heat medium. The user-side heat exchanger 31 is provided in an indoor unit (not shown) installed indoors, and indoor air flows into the user-side heat exchanger 31 by an airflow generated by a blower fan (not shown). In the user-side heat exchanger 31, water as a heat medium and air in the room where the indoor unit is installed exchange heat, and the air that has exchanged heat with the water as a heat medium is used for heating. The high end heat exchanger 11 is a heat exchanger in which water as a heat medium and the high end refrigerant flowing through the high end refrigerant circuit 2 exchange heat. The low-base heat exchanger 24 is a heat exchanger in which water as a heat medium and the low-base refrigerant flowing through the low-base refrigerant circuit 3 exchange heat. Arrows in the heat medium circuit 4 indicate the flow of water as a heat medium.

In addition, one end of the heat medium circuit 4 is connected to piping between the usage side heat exchanger 31 and the low source side heat exchanger 24, and the other end is connected to the piping between the low source side heat exchanger 24 and the high source side heat exchanger. 11 is provided. A first three-way valve 34 (first switching means) is provided on one side of the first bypass path 33, and the first three-way valve 34 is configured to allow water as a heat medium to flow between the first circulation pump 30, the user-side heat exchanger 31, and the user-side heat exchanger 30. , the low source side heat exchanger 24, the high source side heat exchanger 11, the first heat medium circulation path 35 that circulates with the first circulation pump 30, the first circulation pump 30, the usage side heat exchanger 31, and the first bypass. The circuit 33, the high-side heat exchanger 11, the first circulation pump 30, and the circulating second heat medium circulation path 36 are switched.

The binary refrigeration system 1 operates in a first mode in which the heat medium flows through the first heat medium circulation path 35 and in a second mode in which the heat medium does not flow through the low-side heat exchanger 24 but flows in the second heat medium circulation path 36. Have driving. FIG. 1B shows a state in which the heat medium circulates through the first heat medium circulation path 35 in the first mode of operation. FIG. 1C shows a state in which the heat medium circulates through the second heat medium circulation path 36 in the second mode of operation. In the first mode of operation, heat absorbed from outside air by the heat source side heat exchanger 22 of the low source side refrigerant circuit 3 is transferred to the high source side heat exchanger 11 of the high source side refrigerant circuit 2 and the low source side heat exchanger 22 of the low source side refrigerant circuit 3. This is a heating operation in which heat is radiated to the indoor air via the source heat exchanger 24. In the second mode operation, the heat medium return temperature measured by the heat medium return temperature detection sensor 24c, which is the temperature of the heat medium flowing out from the utilization side heat exchanger 31 and flowing into the low source side heat exchanger 24, is When the temperature approaches the condensation temperature of the low-base refrigerant flowing into the low-base heat exchanger 24 measured by the temperature detection sensor 24a, the heat medium does not flow through the low-base heat exchanger 24 and the second heat medium circulation is started. This is an operation that circulates around road 36.

The binary refrigeration system 1 utilizes the latent heat of the high temperature side refrigerant in the high temperature side refrigerant circuit 2, the latent heat of the low temperature side refrigerant in the low temperature side refrigerant circuit 3, and the heat medium (water) in the heat medium circuit 4. ) is a refrigeration system that uses sensible heat. In this embodiment, the high-temperature side refrigerant in the high-temperature side refrigerant circuit 2 and the low-temperature side refrigerant in the low-temperature side refrigerant circuit 3 are the same refrigerant, but they do not necessarily have to be the same. It may be used as a low-source refrigerant that has a lower boiling point than the side refrigerant. Furthermore, a refrigerant that can utilize changes in latent heat may be used in the heat medium circuit. In that case, the first circulation pump 30 of the heat medium circuit 4 is replaced with a compressor, and an expansion valve or the like is provided as a pressure reduction mechanism in the path between the utilization side heat exchanger 31 and the low source side heat exchanger 24.

In the binary refrigeration system 1, the low source refrigerant, which absorbs heat from the outside air in the heat source side heat exchanger 22 of the low source side refrigerant circuit 3 and becomes a low temperature, low pressure gas phase refrigerant, is compressed by the low source side compressor 20. It becomes a high-temperature, high-pressure gas-phase refrigerant, and radiates heat to the high-end refrigerant circulating in the high-end refrigerant circuit 2 via the cascade heat exchanger 13, thereby becoming a high-temperature, high-pressure liquid-phase refrigerant. The low-pressure high-side refrigerant that has absorbed heat from the low-side refrigerant in the cascade heat exchanger 13 is compressed by the high-side compressor 10 to become a high-temperature, high-pressure gas-phase refrigerant, and the heat is transferred to the high-side heat exchanger 11. Heat is radiated to water, which is a heat medium, circulating through the medium circuit 4 to produce hot water. In the binary refrigeration system 1, the low-source refrigerant, which has absorbed heat from the outside air in the heat source-side heat exchanger 22 of the low-source refrigerant circuit 3 and has become a low-temperature, low-pressure gas phase refrigerant, is compressed in the low-source compressor 20. The refrigerant is converted into a high-temperature, high-pressure gas-phase refrigerant, and radiates heat to water, which is a heat medium, circulating through the heat medium circuit 4 via the low-source heat exchanger 24. Therefore, the low-base refrigerant circulating in the low-base refrigerant circuit 3 can be condensed by water, which is a heat medium circulating in the heat medium circuit 4.

In the conventional dual refrigeration system, the ratio (R1/R2) of the rotation speed (R1) of the compressor of the high-side refrigeration circuit to the rotation speed (R2) of the compressor of the low-side refrigeration circuit during start-up operation is: By setting the ratio higher than the ratio in steady operation, it is possible to prevent the compressor of the low source side refrigerant circuit from stopping for protection due to high pressure overrise due to no condensation in the low source side refrigerant circuit. However, in the conventional technology, the rotational speed of the compressor in the low-source refrigeration circuit during start-up operation is limited, so it takes time to demonstrate sufficient heating capacity during start-up operation. On the other hand, the binary refrigeration system 1 in this embodiment includes a high-base refrigerant circuit 2 and a low-base refrigerant circuit 3 having a first circulation path 23 and a second circulation path 26, and in the first mode operation, The heat medium circulating in the heat medium circuit 4 and the heat exchanger 11 of the high source side refrigerant circuit 2 and the low source side heat exchanger 24 in the second circulation path 26 of the low source side refrigerant circuit 3 Exchange. Therefore, since the low-base refrigerant circulating in the low-base refrigerant circuit 3 and the heat medium circulating in the heat transfer medium circuit 4 can be directly exchanged and condensed, the compressor of the low-base refrigerating circuit Start-up operation can be performed quickly while suppressing the protective stoppage of the system.

On the other hand, if the first mode operation continues, the air that has exchanged heat with the heat medium in the user-side heat exchanger 31 becomes warmer, so it eventually flows out of the user-side heat exchanger 31 and is exchanged for low-source heat exchange. The temperature of the heat medium flowing into the heat exchanger 24 (heat medium return temperature) approaches the condensation temperature of the low-side refrigerant flowing into the low-side heat exchanger 24. In this state, the low source side refrigerant cannot be condensed in the low source side heat exchanger 24. By distributing a large amount of uncondensed gas-phase refrigerant in the low-source heat exchanger 24, where a large amount of low-source refrigerant in a liquid phase is originally distributed, the refrigerant in the low-source side refrigeration circuit is instead transferred to other paths ( For example, an excessive amount of the low-base refrigerant in a liquid phase accumulates in an accumulator (not shown) provided on the suction side of the low-base compressor 20. Therefore, there is a possibility that liquid compression will occur in the low-base compressor 20. Furthermore, if the rotation speed of the low-base compressor 20 is increased in order to allow the low-base refrigerant to be condensed in the low-base heat exchanger 24, the reliability of the low-base compressor 20 may decrease.

However, the binary refrigeration system 1 in this embodiment has a second mode operation in which the heat medium does not flow into the low-side heat exchanger 24 but flows through the second heat medium circulation path 36. In the second mode of operation, when the heat medium return temperature of the heat medium becomes high and approaches the condensation temperature of the low source side refrigerant, the heat medium does not flow through the low source side heat exchanger 24 and the second heat medium circulation path 36 This is a cycle operation. By performing the second mode operation, the high-temperature heat medium does not flow into the low-base heat exchanger 24, so the low-base refrigerant passes through the low-base heat exchanger 24 and the refrigerant piping 6 to the surroundings. exchange heat with the air. As a result, it is possible to suppress the inability of the low-base refrigerant flowing into the low-base heat exchanger 24 to condense. can be used as a condenser. In addition, since the binary refrigeration apparatus 1 in this embodiment has the second mode of operation, the low source side heat exchanger 24 is a double pipe heat exchanger having an outer circumferential side flow path and an inner circumferential side flow path. Preferably, the structure is such that the low-base refrigerant flows in the outer circumferential flow path, and water, which is a heat medium, flows in the inner circumferential flow path. This makes it easier for the low-base refrigerant to dissipate heat and facilitate condensation.

Next, with reference to FIG. 2, a control block in the binary refrigeration system 1 of this embodiment will be described. The control unit 5 includes a first degree of supercooling calculation means 45 , a second degree of supercooling calculation means 46 , and a storage means 47 . The first degree of subcooling calculation means 45 calculates the degree of subcooling of the lower-side refrigerant in the cascade heat exchanger 13 . The second degree of subcooling calculation means 46 calculates the degree of subcooling of the low-base refrigerant in the low-base heat exchanger 24 . Further, the storage means 47 stores, for example, data such as target temperature, control software, a program for calculating the degree of supercooling, and the like. The first subcooling degree calculating means 45 includes the condensation temperature of the lower side refrigerant flowing through the cascade heat exchanger 13 measured by the condensation temperature detection sensor 13a and the cascade heat exchanger 13 measured by the outlet temperature detection sensor 13b. The outlet temperature of the flowing low-side refrigerant is input. The second supercooling degree calculation means 46 includes the condensation temperature of the low-base refrigerant flowing through the low-base heat exchanger 24 measured by the condensation temperature detection sensor 24a and the low-base heat measured by the outlet temperature detection sensor 24b. The outlet temperature of the low-side refrigerant flowing through the exchanger 24 is input. Further, the target heat medium temperature is input to the control unit 5 . The target heat medium temperature is the target temperature of water as a heat medium flowing out from the first circulation pump 30 in the heat medium circuit 4 . The target heat medium temperature is changed, for example, depending on the air conditioning load (difference between the room temperature of the air-conditioned space and the set temperature determined by the user) during heating operation using the user-side heat exchanger 31. The larger the air conditioning load, the larger the target heat medium temperature is set.

Further, the control unit 5 receives input of the heat medium return temperature measured by the heat medium return temperature detection sensor 24c and the condensation temperature of the low source side heat exchanger 22 measured by the condensation temperature detection sensor 22a. The first three-way valve 34 is controlled based on the heat medium return temperature and the condensation temperature of the low source heat exchanger 22 that are input to the control unit 5.

The control unit 5 determines the rotation speeds of the high-temperature side compressor 10 and the low-temperature side compressor 20 based on the target heat medium temperature. Furthermore, the first expansion valve 21 on the low base side is controlled based on the degree of subcooling of the low base refrigerant in the cascade heat exchanger 13 calculated by the first degree of supercooling calculating means 45 . Furthermore, the second low-base expansion valve 25 is controlled based on the degree of subcooling of the low-base refrigerant in the low-base heat exchanger 24 calculated by the second subcooling degree calculating means 46 .

Next, control of the binary refrigeration system 1 according to this embodiment will be described with reference to the control flow diagram shown in FIG. 3.

The control unit first starts the first operation mode (ST1). In the first operation mode, the first three-way valve 34 is switched so that the heat medium flows through the first heat medium circulation path 35 . Next, the first circulation pump 30 is started (ST2). Next, start-up operation is performed (ST3). In the start-up operation, the high-base compressor 10 and the low-base compressor 20 are started, and the opening degrees of the high-base expansion valve 12, the low-base first expansion valve 21, and the low-base second expansion valve 25 are set to a predetermined value. Maintaining the initial opening degree, the high-base refrigerant is circulated through the high-base refrigerant circuit 2, and the low-base refrigerant is circulated through the first circulation path 23 and the second circulation path 26 of the low-base refrigerant circuit 3. . The initial opening degree is the degree of opening of the high-temperature side expansion valve 12 and the low-temperature side first expansion valve from when the binary refrigeration system 1 starts operation until the high-temperature side refrigerant circuit 2 and the low-temperature side refrigerant circuit 3 are stabilized. 21 and the opening degree of the second low-base expansion valve 25, which is determined by the performance of the high-base compressor 10 and the low-base compressor 20 and is set in advance.

Next, after a predetermined period of time has elapsed, the start-up operation is ended (ST4). The predetermined time is, for example, 10 minutes. The predetermined time is the minimum required time until the binary refrigeration system 1 reaches a stable operating state converged according to the load, and is determined in advance through experiments or the like. After the start-up operation is completed, the operation is switched to normal operation (ST5). In normal operation, the low-side refrigerant at the outlet of the cascade heat exchanger 13 and the low-side refrigerant at the outlet of the low-side heat exchanger 24 are heated to a predetermined degree of supercooling (a preset fixed value, and each The first low-base expansion valve 21 and the second low-base expansion valve 25 are controlled so that the low-base refrigerant in the two-phase state does not flow into the expansion valve (a value of at least 1 degree or more). In addition, the high-end expansion valve 12 sets the degree of suction superheat of the high-end compressor 10 to a target value (a fixed value set in advance), so that the high-end refrigerant sucked into the high-end compressor 10 is properly controlled. The suction superheat degree is controlled to a value of 1 degree or more so as to be in a refrigerant state. Note that the high-end expansion valve 12 may perform target discharge temperature control or subcooling degree control instead of suction superheating degree control. Next, it is determined whether the return temperature of the heat medium after flowing out from the utilization side heat exchanger 31 is lower than a predetermined value (first predetermined temperature) (ST6). The predetermined value (first predetermined temperature) is a variable, and is, for example, a temperature 2° C. lower than the condensation temperature of the low-source refrigerant. The conditions of ST6 are the return temperature of the heat medium after flowing out from the utilization side heat exchanger 31 and the low source side flowing into the low source side heat exchanger 24 measured by the condensation temperature detection sensor 24a of the low source side refrigerant circuit 3. The determination may be made based on whether the difference from the condensation temperature of the refrigerant is equal to or higher than a second predetermined temperature. The second predetermined temperature is a value below which the low-base refrigerant will not condense in the low-base heat exchanger 24 and liquid compression may occur in the low-base compressor 20. If the heat medium return temperature is not lower than the predetermined value (No in ST6), the second operation mode is started (ST7). In the second operation mode, the first three-way valve 34 is switched so that the heat medium flows through the second heat medium circulation path 36. If the heat medium return temperature is not lower than a predetermined value, the low source refrigerant in the high temperature and high pressure gas phase state passing through the low source side heat exchanger 24 cannot radiate heat, but by performing the second operation mode. The high-temperature heat medium no longer flows into the low-side heat exchanger 24. Therefore, the low-base refrigerant flowing into the low-base heat exchanger 24 exchanges heat with the surrounding air via the low-base heat exchanger 24 and the refrigerant piping 6 and radiates heat, making it impossible for the low-base refrigerant to condense. This can be suppressed. Next, target subcooling degree control is performed so that the degree of subcooling of the low source side refrigerant at the outlet of the low source side heat exchanger 24 becomes the target degree of supercooling (ST8). When the target supercooling degree control is performed, the opening degree of the low-side second expansion valve 25 is controlled in the closing direction so that supercooling can be achieved, and eventually it is closed or slightly opened. The target degree of supercooling control is control of the second expansion valve 25 on the lower side through the second degree of supercooling calculation means 46 .

Next, it is determined whether the defrosting start conditions are satisfied (ST9). Defrosting start conditions include, for example, when the outside temperature is 5° C. or lower and the heating operation is continued for 3 hours, or when the temperature detected by the condensing temperature detection sensor 22a of the heat source side heat exchanger 22 becomes -15° C. or lower. This is the case. When the defrosting start condition is satisfied (Yes in ST9), the low-side four-way valve 27 is switched to the so-called cooling cycle side to start defrosting operation (ST14), and after a predetermined period of time, the defrosting operation is ended. (ST15). The predetermined time is a preset time, and is a sufficient time (for example, 10 minutes) to melt the frost attached to the heat source side heat exchanger 22 during the defrosting operation. On the other hand, if the defrosting start condition is not satisfied (No in ST9), it is determined whether the heat medium return temperature is lower than a predetermined value (ST10). If the heat medium return temperature is not lower than the predetermined value (No in ST10), the process returns to before ST9 and target supercooling degree control is continued. If the heat medium return temperature is lower than the predetermined value (Yes in ST10), the mode is switched to the first operation mode (ST11). In the first operation mode, the first three-way valve 34 is switched so that the heat medium flows through the first heat medium circulation path 35. As a result, the opening degree of the low-side second expansion valve 25 is controlled from the closed or slightly open state to the open direction by target supercooling degree control (ST12). After switching to the first operation mode, when target supercooling degree control is performed, the high temperature and high pressure gas phase low source refrigerant passing through the low source heat exchanger 24 can radiate heat and condense. The opening degree is controlled in the direction of opening the second expansion valve 25 so that the degree of subcooling of the low source refrigerant after passing through the low source heat exchanger 24 becomes the target degree of supercooling. The target degree of supercooling control is control of the second expansion valve 25 on the lower side through the second degree of supercooling calculation means 46 . The target supercooling degree control is continued and the process returns to before ST6.

If the heat medium return temperature is lower than the predetermined value (Yes in ST6), it is determined whether the defrosting start condition is satisfied (ST13). The defrosting start condition is determined based on the outside air temperature and the temperature detected by the condensing temperature detection sensor 22a of the heat source side heat exchanger 22. When the defrosting start condition is satisfied (Yes in ST13), the defrosting operation is started (ST14), and the defrosting operation is ended after a predetermined time has elapsed (ST15). On the other hand, if the defrosting start condition is not satisfied (No in ST13), the process returns to before ST6 and it is determined whether the heat medium return temperature is lower than a predetermined value (ST6).

Next, a binary refrigeration device 50 as another embodiment will be described with reference to FIGS. 4A to 4C. FIG. 4A is a refrigerant circuit diagram of a binary refrigeration device 50 according to another embodiment. FIG. 4B is a diagram illustrating the flow of refrigerant in the first mode operation of the binary refrigeration system 50 according to another embodiment of the present invention. Moreover, FIG. 4C is a diagram showing the flow of refrigerant in the second mode operation of the binary refrigeration apparatus 50 according to another embodiment of the present invention. The difference between the binary refrigeration system 1 of the first embodiment and the binary refrigeration system 50 of other embodiments is that one end is connected to the piping 32 between the first three-way valve 34 and the low-side heat exchanger 24, The other configuration is the same except that a second bypass passage 37 is provided, the other end of which is connected to the piping 32 between the low-side heat exchanger 24 and the other end of the first bypass passage 33. , Therefore, a detailed description of the same configuration as that of the binary refrigeration apparatus 1 of the first embodiment will be omitted. In addition, the same reference numerals are used for the same configurations.

The binary refrigeration system 50 is used for cooling operation when the user-side heat exchanger 31 is used as an evaporator, and for operation for producing hot water when the user-side heat exchanger 31 is used as a condenser. , is a refrigeration device that can be used for heating operation. Hereinafter, the operation for producing hot water and the heating operation may be collectively referred to as the heating operation. In this embodiment, a binary refrigeration system used for heating operation will be described.

The binary refrigeration system 50 includes a high-temperature side refrigerant circuit 2, a low-temperature side refrigerant circuit 3, a heat medium circuit 4, and a control section 5, and the control section 5 controls the binary refrigeration system 50. The heat medium circuit 4 includes a first bypass path 33 and a second bypass path 37. The first bypass path 33 has one end connected to the piping 32 between the utilization side heat exchanger 31 and the low source side heat exchanger 24, and the other end connected to the low source side heat exchanger 24 and the high source side heat exchanger. It is connected to the piping between 11 and 11. The second bypass path 37 has one end connected to the piping 32 between the first three-way valve 34 and the low-side heat exchanger 24, and the other end connected to the piping 32 between the low-side heat exchanger 24 and the first bypass path 33. It is connected to the piping 32 between the two ends.

In the second bypass path 37, a second three-way valve 38, which is a second switching means, is provided at the other end of the second bypass path 37, and the heat storage material is directed from the other end of the second bypass path 37 to one end. A heat storage section 39 (corresponding to a second heat storage section), a second circulation pump 40, and a check valve 41 are provided. The second three-way valve 38 switches water as a heat medium between flowing through the first heat medium circulation path 35 and flowing through the third heat medium circulation path 42 . The heat storage section 39 stores the heat absorbed from the low-base refrigerant by the low-base heat exchanger 24 via water as a heat medium. Further, the heat storage section 39 is provided with a temperature detection sensor 39a that measures the temperature of the heat storage section 39. The second circulation pump 40 causes water as a heat medium to flow from the other end of the second bypass path 37 to one end. The check valve 41 is a valve that allows water as a heat medium to flow from the other end of the second bypass path 37 to one end, but prevents it from flowing from one end to the other end.

The binary refrigeration device 50 operates in a first mode operation in which the heat medium flows through the first heat medium circulation path 35 and in a second mode operation in which the heat medium flows in the second heat medium circulation path 36 and the third heat medium circulation path 42. have. In the first mode of operation, the heat source side heat exchanger 22 of the low source side refrigerant circuit 3 absorbs heat from outside air, and the heat absorbed from the outside air is transferred to the high source side heat exchanger 11 of the high source side refrigerant circuit 2 and the low source side refrigerant. This is an operation in which heat is radiated to the heat medium of the heat medium circuit 4 via the low-side heat exchanger 24 of the circuit 3, and heat is radiated from the heat medium of the heat medium circuit 4 that has absorbed heat to the indoor air. The second mode operation is an operation in which heat is absorbed from the outside air by the heat source side heat exchanger 22 of the low source side refrigerant circuit 3, and heat is radiated from the heat medium of the heat medium circuit 4 to the indoor air via the high source side refrigerant circuit 2. , the heat source side heat exchanger 22 of the low source side refrigerant circuit 3 absorbs heat from the outside air, and the heat absorbed from the outside air is stored in the heat storage section 39 of the heat medium circuit 4.

In the first heat medium circulation path 35, the heat medium circulates through the first circulation pump 30, the usage side heat exchanger 31, the low source side heat exchanger 24, the high source side heat exchanger 11, and the first circulation pump 30. It is a circulation route. The second heat medium circulation path 36 is a circulation path in which the heat medium circulates through the first circulation pump 30, the utilization side heat exchanger 31, the first bypass path 33, the high source side heat exchanger 11, and the first circulation pump 30. It is. The third heat medium circulation path 42 is a circulation path in which the heat medium circulates through the second circulation pump 40 of the second bypass path 37, the check valve 41, the low-side heat exchanger 24, and the second circulation pump 40. .

Next, with reference to FIG. 5, a control block in the binary refrigeration system 50 of this embodiment will be described. The control unit 5 includes a first degree of supercooling calculation means 45 , a second degree of supercooling calculation means 46 , and a storage means 47 . The first degree of subcooling calculation means 45 calculates the degree of subcooling of the lower-side refrigerant in the cascade heat exchanger 13 . The second degree of subcooling calculation means 46 calculates the degree of subcooling of the low-base refrigerant in the low-base heat exchanger 24 . Further, the storage means 47 stores, for example, data such as target temperature, control software, a program for calculating the degree of supercooling, and the like. As described above, the first supercooling degree calculating means 45 includes the condensation temperature of the lower refrigerant flowing through the cascade heat exchanger 13 measured by the condensation temperature detection sensor 13a and the cascade temperature measured by the outlet temperature detection sensor 13b. The outlet temperature of the low-end refrigerant flowing through the heat exchanger 13 is input. The second subcooling degree calculating means 46 includes the condensation temperature of the low-base refrigerant flowing through the low-base heat exchanger 24 measured by the condensation temperature detection sensor 24a and the low-base heat measured by the outlet temperature detection sensor 24b. The outlet temperature of the low-side refrigerant flowing through the exchanger 24 is input. Further, the target heat medium temperature is input to the control unit 5 . The target heat medium temperature is the target temperature of water as a heat medium flowing out from the first circulation pump 30 in the heat medium circuit 4 . The target heat medium temperature is changed depending on, for example, the air conditioning load (the difference between the room temperature of the air-conditioned space and the set temperature determined by the user) during heating operation using the user-side heat exchanger 31. , the larger the air conditioning load, the larger the target heat medium temperature is set.

The control unit 5 also includes the heat medium return temperature measured by the heat medium return temperature detection sensor 24c, the condensation temperature of the low source side heat exchanger 24 measured by the condensation temperature detection sensor 22a, and the temperature measured by the temperature detection sensor 39a. The temperature of the heat storage section 39 is input. The first three-way valve 34, the second three-way valve 38, and the second circulation pump 40 are controlled based on the heat medium return temperature, the temperature of the low-source side heat exchanger 24, and the temperature of the heat storage section 39 input into the control unit 5. conduct. That is, in order to prevent the heat medium return temperature from becoming higher than the condensation temperature of the low-source side refrigerant flowing into the low-source side heat exchanger 24, the heat medium is caused to radiate heat in the heat storage section 39.

The control unit 5 determines the rotation speeds of the high-temperature side compressor 10 and the low-temperature side compressor 20 based on the target heat medium temperature. Further, based on the condensation temperature of the high-base refrigerant flowing through the cascade heat exchanger 13 and the outlet temperature of the high-base refrigerant flowing through the cascade heat exchanger 13, the first The expansion valve 21 is controlled. Further, based on the condensation temperature of the low-base refrigerant flowing through the low-base heat exchanger 24 and the outlet temperature of the low-base refrigerant flowing through the low-base heat exchanger 24, the subcooling degree calculation means 46 calculates the The source-side second expansion valve 25 is controlled.

In the binary refrigeration system 50 of this embodiment, the heat stored in the heat storage unit 39 in the second mode operation is used for a defrosting operation for defrosting frost formed on the heat source side heat exchanger 22. Defrosting operation is performed as follows. The high end compressor 10 of the high end refrigerant circuit 2 is stopped, and the low end four-way valve 27 in the low end refrigerant circuit 3 is switched to the so-called cooling cycle side. That is, the low source side refrigerant discharged from the low source side compressor 20 is switched to flow to the heat source side heat exchanger 22 side, the heat source side heat exchanger 22 is made to function as a condenser, and the cascade heat exchanger 13 and the lower side heat exchanger 24 function as an evaporator. The first low-base expansion valve 21 and the second low-base expansion valve 25 are opened close to fully open. The low-base refrigerant discharged from the low-base compressor 20 flows into the heat source-side heat exchanger 22 to melt frost. A part of the low source side refrigerant flowing out from the heat source side heat exchanger 22 flows into the low source side heat exchanger 24 and absorbs heat from the heat medium circulating through the third heat medium circulation path 42 in which the heat storage section 39 is provided. . The remaining low-end refrigerant that has flowed out of the heat source-side heat exchanger 22 flows into the cascade heat exchanger 13 and absorbs the heat remaining in the high-end refrigerant circuit 2 where the high-end compressor 10 has stopped. The heat-absorbed low-base refrigerant passes through the low-base compressor 20 and flows into the heat source heat exchanger 22 again to melt the frost.

Control of the binary refrigeration system 50 according to this embodiment will be described with reference to the control flow diagram shown in FIG. 6.

The control unit first starts the first operation mode (ST21). In the first operation mode, the first three-way valve 34 is switched so that the heat medium flows through the first heat medium circulation path 35 . Next, the first circulation pump 30 is started (ST22). Next, start-up operation is performed (ST23). In the start-up operation, the high-base compressor 10 and the low-base compressor 20 are started, and the opening degrees of the high-base expansion valve 12, the low-base first expansion valve 21, and the low-base second expansion valve 25 are set to a predetermined value. Maintaining the initial opening degree, the high-base refrigerant is circulated through the high-base refrigerant circuit 2, and the low-base refrigerant is circulated through the first circulation path 23 and the second circulation path 26 of the low-base refrigerant circuit 3. . The initial opening degree is the degree of opening of the high-temperature side expansion valve 12 and the low-temperature side first expansion valve from when the binary refrigeration system 1 starts operation until the high-temperature side refrigerant circuit 2 and the low-temperature side refrigerant circuit 3 are stabilized. 21 and the opening degree of the second low-base expansion valve 25, which is determined by the performance of the high-base compressor 10 and the low-base compressor 20 and is set in advance.

Next, after a predetermined period of time has elapsed, the start-up operation is ended (ST24). The predetermined time is, for example, 10 minutes. The predetermined time is the minimum required time until the binary refrigeration system 1 reaches a stable operating state converged according to the load, and is determined in advance through experiments or the like. After the start-up operation is completed, the operation is switched to normal operation (ST25). In normal operation, the low-side refrigerant at the outlet of the cascade heat exchanger 13 and the low-side refrigerant at the outlet of the low-side heat exchanger 24 are heated to a predetermined degree of subcooling (a preset fixed value, and each expansion The first low-base expansion valve 21 and the second low-base expansion valve 25 are controlled so that the low-base refrigerant in the two-phase state does not flow into the valves (a value of at least 1 degree or more). In addition, the high-end expansion valve 12 sets the degree of suction superheat of the high-end compressor 10 to a target value (a fixed value set in advance), so that the high-end refrigerant sucked into the high-end compressor 10 is properly controlled. The suction superheat degree is controlled to a value of 1 degree or more so as to be in a refrigerant state. Note that the high-end expansion valve 12 may perform target discharge temperature control or subcooling degree control instead of suction superheating degree control. Next, it is determined whether the return temperature of the heat medium after flowing out from the utilization side heat exchanger 31 is lower than a predetermined value (first predetermined temperature) (ST26). The predetermined value (first predetermined temperature) is a variable, and is, for example, a temperature 2° C. lower than the condensation temperature of the low-source refrigerant. The conditions of ST26 are the return temperature of the heat medium after flowing out from the utilization side heat exchanger 31 and the low source side flowing into the low source side heat exchanger 24 measured by the condensation temperature detection sensor 24a of the low source side refrigerant circuit 3. The determination may be made based on whether the difference from the condensation temperature of the refrigerant is equal to or higher than a second predetermined temperature. The second predetermined temperature is a value below which the low-base refrigerant will not condense in the low-base heat exchanger 24 and liquid compression may occur in the low-base compressor 20. If the heat medium return temperature is not lower than the predetermined value (No in ST26), the second operation mode is started (ST27). The second operation mode is an operation in which the first three-way valve 34 is switched so that the heat medium flows through the second heat medium circulation path 36, and the heat absorbed from the outside air is stored in the heat storage section 39 of the heat medium circuit 4. The second operation mode is performed for a predetermined period of time to complete heat storage in the heat storage section 39 (ST28). Next, target subcooling degree control is performed so that the degree of subcooling of the low source side refrigerant at the outlet of the low source side heat exchanger 24 becomes the target degree of supercooling (ST29). When the target supercooling degree control is performed, the opening degree of the low-side second expansion valve 25 is controlled in the closing direction so that supercooling can be achieved, and eventually it is closed or slightly opened. The target degree of supercooling control is control of the second expansion valve 25 on the lower side through the second degree of supercooling calculation means 46 .

Next, it is determined whether the defrosting start conditions are satisfied (ST30). Defrosting start conditions include, for example, when the outside temperature is 5°C or lower and the heating operation continues for 3 hours, or when the temperature detected by the condensing temperature detection sensor 22a of the heat source side heat exchanger 22 is -15°C or lower. This is the case. When the defrosting start condition is satisfied (Yes in ST30), the low-side four-way valve 27 is switched to the so-called cooling cycle side to start defrosting operation (ST35), and after a predetermined period of time, the defrosting operation is ended. (ST36). The predetermined time is a preset time, and is a sufficient time (for example, 10 minutes) to melt the frost attached to the heat source side heat exchanger 22 during the defrosting operation. On the other hand, if the defrosting start condition is not satisfied (No in ST30), it is determined whether the heat medium return temperature is lower than a predetermined value (ST31). If the heat medium return temperature is not lower than the predetermined value (No in ST31), the process returns to before ST30 and target supercooling degree control is continued. If the heat medium return temperature is lower than the predetermined value (Yes in ST31), the mode is switched to the first operation mode (ST32). In the first operation mode, the first three-way valve 34 is switched so that the heat medium flows through the first heat medium circulation path 35. As a result, the opening degree of the low-side second expansion valve 25 is controlled from the closed or slightly open state to the open direction by target supercooling degree control (ST33). After switching to the first operation mode, when target supercooling degree control is performed, the high temperature and high pressure gas phase low source refrigerant passing through the low source heat exchanger 24 can radiate heat and condense. The opening degree is controlled in the direction of opening the second expansion valve 25 so that the degree of subcooling of the low source refrigerant after passing through the low source heat exchanger 24 becomes the target degree of supercooling. The target degree of supercooling control is control of the second expansion valve 25 on the lower side through the second degree of supercooling calculation means 46 . The target supercooling degree control is continued and the process returns to before ST26.

If the heat medium return temperature is lower than the predetermined value (Yes in ST26), it is determined whether the defrosting start condition is satisfied (ST34). The defrosting start conditions are conditions related to the outside air temperature and the temperature detected by the condensing temperature detection sensor 22a of the heat source side heat exchanger 22 as described above. When the defrosting start condition is satisfied (Yes in ST34), it is determined whether the heat storage temperature of the heat storage section 39 is higher than a predetermined value (ST37). The predetermined value is determined in advance through a test or the like, and is a temperature at which it can be determined that a sufficient amount of heat storage that can be used for defrosting operation is obtained. If the heat storage temperature of the heat storage section 39 is higher than the predetermined value (ST37: Yes), the defrosting operation is started (ST35), and the defrosting operation is ended after a predetermined time has elapsed (ST36). On the other hand, if the heat storage temperature of the heat storage section 39 is not higher than the predetermined value (No in ST37), the second operation mode is started (ST38). The second operation mode is an operation in which the first three-way valve 34 is switched so that the heat medium flows through the second heat medium circulation path, and the heat absorbed from the outside air is stored in the heat storage section 39 of the heat medium circuit 4. The second operation mode is performed for a predetermined period of time to complete heat storage in the heat storage section 39 (ST39). Next, the defrosting operation is started (ST35), and the defrosting operation is ended after a predetermined period of time has passed (ST36).

Although the embodiments have been described above with reference to a limited number of embodiments, the scope of rights is not limited thereto, and modifications of the embodiments based on the above disclosure will be obvious to those skilled in the art.

DESCRIPTION OF SYMBOLS 1... Binary refrigeration device, 2... High source side refrigerant circuit, 3... Low source side refrigerant circuit, 4... Heat medium circuit, 5... Control part, 6... Refrigerant piping, 10... High source side compressor, 11... High source side Source side heat exchanger, 12... High source side expansion valve, 13... Cascade heat exchanger, 13a... Condensing temperature detection sensor, 13b... Outlet temperature detection sensor, 14... High source side four-way valve, 20... Low source side compressor , 21...Low source side first expansion valve, 22...Heat source side heat exchanger, 22a...Condensing temperature detection sensor, 23...First circulation path, 24...Low source side heat exchanger, 24a...Condensing temperature detection sensor, 24b ...Outlet temperature detection sensor, 24c...Heat medium return temperature detection sensor, 25...Low source side second expansion valve, 26...Second circulation path, 27...Low source side four-way valve, 30...First circulation pump, 31...Usage Side heat exchanger, 32... Piping, 33... First bypass path, 34... First three-way valve, 35... First heat medium circulation path, 36... Second heat medium circulation path, 37... Second bypass path, 38... Second three-way valve, 39... Heat storage unit, 39a... Temperature detection sensor, 40... Second circulation pump, 41... Check valve, 42... Third heat medium circulation path, 45... First supercooling degree calculation means, 46... Second supercooling degree calculation means, 47... Storage means, 50... Binary refrigeration device

Claims (9)

a high-base refrigerant circuit in which a high-base compressor, a high-base heat exchanger, a high-base pressure reduction mechanism, and a cascade heat exchanger are sequentially connected by refrigerant piping, and the high-base refrigerant circulates;
a first circulation path in which a low source side compressor, the cascade heat exchanger, a first low pressure reducing mechanism, and a heat source side heat exchanger are sequentially connected by refrigerant piping, and in which the low source side refrigerant circulates;
A low source side heat exchange is performed between the low source side compressor and the cascade heat exchanger and between the low source side first pressure reduction mechanism and the heat source side heat exchanger in the first circulation path. The low source side compressor, the low source side heat exchanger, the low source second pressure reducing mechanism, and the heat source side heat a low-source refrigerant circuit, comprising a second circulation path in which the low-source refrigerant circulates, the exchanger being sequentially connected to the exchanger through refrigerant piping;
The first circulation pump, the utilization side heat exchanger, the low source side heat exchanger, and the high source side heat exchanger are sequentially connected by piping to circulate the heat medium, and the high source side heat exchanger a first heat medium circulation path in which the high-base refrigerant and the heat medium exchange heat in a heat exchanger, and the low-base refrigerant and the heat medium exchange heat in the low-base heat exchanger;
Connecting between the utilization side heat exchanger and the low source side heat exchanger and between the low source side heat exchanger and the high source side heat exchanger in the first heat medium circulation path. A first bypass path is provided, the first circulation pump, the usage side heat exchanger, the first bypass path, and the high source side heat exchanger are sequentially connected by piping, and the heat medium circulates. a heat medium circuit comprising a second heat medium circulation path;
The high-end refrigerant and the low-end refrigerant exchange heat in the cascade heat exchanger,
In the heat medium circuit, a first switching means for switching whether to flow the heat medium into the first heat medium circulation path or the second heat medium circulation path;
A binary refrigeration system comprising: a control section that controls the high-base refrigerant circuit, the low-base refrigerant circuit, and the heat medium circuit. When starting the binary refrigeration system, the control unit starts the high-temperature side compressor, the low-temperature side compressor, and the first circulation pump, and causes the heat medium to flow through the first heat medium circulation path. The binary refrigeration system according to claim 1, wherein the first switching means is switched in a fluid manner. When the temperature of the heat medium that has passed through the user-side heat exchanger exceeds a first predetermined temperature, or when the temperature of the heat medium that has passed through the user-side heat exchanger and the temperature of the low-source side refrigerant circuit If the difference from the refrigerant condensing temperature in the low source heat exchanger is less than a second predetermined temperature, the first switching means is switched so that the heat medium flows through the second heat medium circulation path. The binary refrigeration system according to claim 2. In the low-base refrigerant circuit, the low-base refrigerant circuit is connected to the discharge side of the low-base compressor, and transfers the low-base refrigerant discharged from the low-base compressor to the cascade heat exchanger side and the low-base heat exchanger. 2. The binary refrigeration system according to claim 1, further comprising a four-way valve for switching whether to flow to the side or to the heat source side heat exchanger side. 5. The binary refrigeration system according to claim 4, wherein the low-source side heat exchanger includes a first heat storage section including a heat storage material. In the heat medium circuit, a second bypass path provided with a check valve, a second circulation pump, and a second heat storage section including a heat storage material is connected in parallel with the first bypass path, and the second bypass path and the second circulation pump are connected in parallel to the first bypass path. , a third heat medium circulation path in which the check valve, the low-side heat exchanger, and the second heat storage section are sequentially connected by refrigerant piping, and the heat medium circulates;
In the heat medium circuit, a second switching means for switching whether the heat medium flows through the first heat medium circulation path or the third heat medium circulation path;
In the low-base refrigerant circuit, the low-base refrigerant circuit is connected to the discharge side of the low-base compressor, and transfers the low-base refrigerant discharged from the low-base compressor to the cascade heat exchanger side and the low-base heat exchanger. The two-way refrigeration system according to claim 1, further comprising a four-way valve for switching whether to flow to the side or to the heat source side heat exchanger side. When starting the binary refrigeration system, the control unit starts the high-temperature side compressor, the low-temperature side compressor, and the first circulation pump, and causes the heat medium to flow through the first heat medium circulation path. 7. The binary refrigeration system according to claim 6, wherein the first switching means and the second switching means are switched in a fluid manner. When the temperature of the heat medium that has passed through the user-side heat exchanger exceeds a first predetermined temperature, or when the temperature of the heat medium that has passed through the user-side heat exchanger and the temperature of the low-source side refrigerant circuit If the difference from the refrigerant condensing temperature in the low source side heat exchanger is less than a second predetermined temperature, the first switching means is switched so that the heat medium flows through the second heat medium circulation path, and the heat medium 8. The binary refrigeration system according to claim 7, wherein the second switching means is switched so that the heat medium flows through the third heat medium circulation path. When the temperature of the heat storage material reaches or exceeds a predetermined temperature when the defrosting start condition is satisfied, the control unit switches the four-way valve to the heat source side heat exchanger side so that heat is stored in the heat storage material. 9. The binary refrigeration system according to claim 8, wherein a defrosting operation is performed to defrost frost formed on the heat source side heat exchanger using the heat generated by the heat exchanger.

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