Triple heat pump system

Abstract

The invention belongs to the technical field of heat pumps, and particularly relates to a triple heat pump system which comprises a compressor, a first heat exchanger, a second heat exchanger and a third heat exchanger. The control unit is used for communicating the other refrigerant inlet and outlet of the target heat exchanger in the first heat exchanger, the second heat exchanger and the third heat exchanger with the air suction pipeline so as to switch the target heat exchanger into an evaporator; and the other refrigerant inlet and outlet of the target heat exchanger communicates with an exhaust pipeline, so that the target heat exchanger is switched into a condenser. The system comprises the three heat exchangers, heating operation and water heating operation can be carried out at the same time, heating operation and refrigerating operation can also be carried out at the same time, and when refrigerating and heating are carried out at the same time, the problems that the temperature change of the heat exchangers is large, waiting time is long, and faults are prone to being generated due to switching of the refrigerating mode and the heating mode can be solved; the three heat exchangers work simultaneously, so that the energy efficiency of the heat pump system can be improved.

Description

Technical Field

[0001] The present application belongs to the field of heat pump technology, and specifically relates to a triple heat pump system. Background Art

[0002] A heat pump is a device that transfers heat from a low-level heat source to a high-level heat source. It is currently widely used in refrigeration, heating, and hot water production.

[0003] The heat pump system generally includes a compressor and two heat exchangers: an evaporator and a condenser. Generally, one of the two heat exchangers is located outdoors and the other is located indoors. The heat pump cycle is as follows: the compressor sucks in gaseous refrigerant from the evaporator, compresses it, and discharges the high-temperature and high-pressure refrigerant to the condenser. The refrigerant evaporates and absorbs heat in the evaporator, and condenses and releases heat in the condenser. Therefore, during cooling operation, the indoor heat exchanger is the evaporator to lower the indoor temperature, and the outdoor heat exchanger is the condenser; during heating operation, the outdoor heat exchanger is the evaporator, and the indoor heat exchanger is the condenser to raise the indoor temperature.

[0004] However, since the existing heat pump system only includes one evaporator and one condenser, it cannot operate heating and hot water at the same time, nor can it operate cooling and heating at the same time. If the user switches between cooling and heating modes, the temperature of a single heat exchanger changes greatly, the waiting time is long, and it is easy to cause the heat pump system to malfunction. Summary of the invention

[0005] The present application provides a triple heat pump system to solve the technical problems of the existing heat pump system: it cannot operate heating and hot water at the same time, nor can it perform cooling and heating at the same time; if the user switches the cooling and heating modes, the temperature of a single heat exchanger changes greatly, the waiting time is very long, and it is easy to cause the heat pump system to malfunction.

[0006] The present application provides a triple heat pump system, the system comprising:

[0007] A compressor, a first heat exchanger, a second heat exchanger, and a third heat exchanger, wherein the compressor inhales refrigerant through an air intake pipeline and discharges refrigerant through an air discharge pipeline, a refrigerant inlet and outlet of the first heat exchanger is connected to each other through a first pipeline, a refrigerant inlet and outlet of the second heat exchanger is connected to each other through a second pipeline, and a refrigerant inlet and outlet of the third heat exchanger is connected to each other through a third pipeline;

[0008] The system further comprises a control unit, which is configured to:

[0009] Connecting another refrigerant inlet and outlet of the target heat exchanger among the first heat exchanger, the second heat exchanger and the third heat exchanger to the air intake pipeline to switch the target heat exchanger to an evaporator;

[0010] The other refrigerant inlet and outlet of the target heat exchanger is connected to the exhaust pipeline to switch the target heat exchanger to a condenser.

[0011] In the above preferred technical solution of the triple heat pump system, the control unit is also used for:

[0012] Connecting another refrigerant inlet and outlet of the first heat exchanger and another refrigerant inlet and outlet of the second heat exchanger to the exhaust pipe, and connecting another refrigerant inlet and outlet of the third heat exchanger to the suction pipe, so that the system can perform heating operation and hot water operation at the same time;

[0013] Connect another refrigerant inlet and outlet of the first heat exchanger to the intake pipe, and connect another refrigerant inlet and outlet of the third heat exchanger and another refrigerant inlet and outlet of the second heat exchanger to the exhaust pipe, so that the system can perform cooling and heating operations simultaneously.

[0014] In the above-mentioned preferred technical solution of the triple heat pump system, the system further includes a four-way reversing valve, the exhaust pipeline is connected to the first refrigerant inlet and outlet of the four-way reversing valve, the suction pipeline is connected to the second refrigerant inlet and outlet of the four-way reversing valve, another refrigerant inlet and outlet of the third heat exchanger is connected to the third refrigerant inlet and outlet of the four-way reversing valve, and another refrigerant inlet and outlet of the first heat exchanger is connected to the fourth refrigerant inlet and outlet of the four-way reversing valve through a fourth pipeline;

[0015] Another refrigerant inlet and outlet of the second heat exchanger is connected to the exhaust pipeline through a fifth pipeline;

[0016] The control unit is specifically used for:

[0017] Controlling the reversing of the four-way reversing valve to connect another refrigerant inlet and outlet of the third heat exchanger with the exhaust pipeline to switch the third heat exchanger into a condenser, and connecting another refrigerant inlet and outlet of the first heat exchanger with the suction pipeline to switch the first heat exchanger into an evaporator;

[0018] Control the reversing of the four-way reversing valve to connect the other refrigerant inlet and outlet of the third heat exchanger with the intake pipeline to switch the third heat exchanger to an evaporator, and connect the other refrigerant inlet and outlet of the first heat exchanger with the exhaust pipeline to switch the first heat exchanger to a condenser.

[0019] In the above preferred technical solution of the triple heat pump system, the first pipeline is provided with a first expansion valve, and the control unit is further used for:

[0020] If the system performs heating operation and cooling operation at the same time, detecting the refrigerant temperatures at two refrigerant inlet and outlet of the first heat exchanger, and adjusting the opening of the first expansion valve according to the refrigerant temperatures at two refrigerant inlet and outlet of the first heat exchanger;

[0021] If the system performs heating operation and hot water heating operation at the same time, the exhaust pipeline refrigerant saturation temperature and the first refrigerant temperature of the refrigerant inlet and outlet connected to the first heat exchanger and the first pipeline are detected, and the opening of the first expansion valve is adjusted according to the difference between the exhaust pipeline refrigerant saturation temperature and the first refrigerant temperature.

[0022] In the above-mentioned preferred technical solution of the triple heat pump system, the control unit is specifically used for:

[0023] The first superheat is calculated according to a first superheat calculation formula, which is:

[0024] SH1=T g1 -T l1

[0025] Wherein, SH1 is the first superheat, T l1 is the first refrigerant temperature of the refrigerant inlet and outlet of the first heat exchanger connected to the first pipeline, T g1 is the refrigerant temperature of another refrigerant inlet and outlet of the first heat exchanger;

[0026] calculating a first superheat difference between the first superheat and the first superheat target value;

[0027] The first expansion valve opening is adjusted according to the numerical range of the first superheat difference. The larger the upper limit of the numerical range of the first superheat difference is, the larger the first expansion valve opening is.

[0028] In the above preferred technical solution of the triple heat pump system, the control unit is also used for:

[0029] If the system performs heating operation and hot water operation at the same time, detecting the exhaust pipe refrigerant saturation temperature and the first refrigerant temperature;

[0030] Calculate a first degree of subcooling by subtracting the first refrigerant temperature from the exhaust pipe refrigerant saturation temperature;

[0031] calculating a first subcooling difference between the first subcooling degree and the first subcooling degree target value;

[0032] The opening of the first expansion valve is adjusted according to the numerical range of the first subcooling difference. The larger the upper limit of the numerical range of the first subcooling difference is, the larger the opening of the first expansion valve is.

[0033] In the above-mentioned preferred technical solution of a triple heat pump system, when the system is in heating operation or cooling operation, the connection between the second heat exchanger and the system is disconnected, and the opening of the first expansion valve is adjusted according to the numerical range of the first superheat difference. The larger the upper limit value of the numerical range of the first superheat difference, the larger the opening of the first expansion valve.

[0034] In the above preferred technical solution of the triple heat pump system, the second pipeline is provided with a second expansion valve, and the control unit is further used for:

[0035] detecting the saturated temperature of the refrigerant in the exhaust pipeline, and detecting the second refrigerant temperature of the refrigerant inlet and outlet of the second heat exchanger connected to the second pipeline;

[0036] Subtracting the second refrigerant temperature from the exhaust pipe refrigerant temperature to calculate a second degree of subcooling;

[0037] calculating a second subcooling difference between the second subcooling degree and the second subcooling degree target value;

[0038] The opening of the second expansion valve is adjusted according to the numerical range of the second subcooling difference. The larger the upper limit of the numerical range of the second subcooling difference is, the larger the opening of the second expansion valve is.

[0039] In the above preferred technical solution of the triple heat pump system, the third pipeline is provided with a third expansion valve, and the control unit is further used for:

[0040] If the system performs heating operation and hot water operation at the same time, adjusting the opening of the third expansion valve according to the suction superheat of the compressor;

[0041] If the system performs heating and cooling operations simultaneously, the exhaust pipeline refrigerant saturation temperature and the third refrigerant temperature of the refrigerant inlet and outlet connected to the third heat exchanger and the third pipeline are detected, and the opening of the third expansion valve is adjusted according to the difference between the exhaust pipeline saturation temperature and the third refrigerant temperature.

[0042] In the above-mentioned preferred technical solution of the triple heat pump system, the control unit is specifically used for:

[0043] If the system performs heating operation and hot water operation at the same time, detecting the refrigerant temperature of the suction pipeline and the saturation temperature of the refrigerant of the suction pipeline;

[0044] Calculate the suction superheat by subtracting the suction pipeline refrigerant saturation temperature from the suction pipeline refrigerant temperature;

[0045] calculating a suction superheat difference between the suction superheat and the suction superheat target value;

[0046] The opening of the third expansion valve is adjusted according to the numerical range of the intake superheat difference. The larger the upper limit of the numerical range of the intake superheat difference is, the larger the opening of the third expansion valve is.

[0047] In the above-mentioned preferred technical solution of the triple heat pump system, the control unit is specifically used for:

[0048] If the system performs heating operation and cooling operation at the same time, detecting the exhaust pipe refrigerant saturation temperature and the third refrigerant temperature;

[0049] Subtracting the third refrigerant temperature from the exhaust pipe refrigerant saturation temperature to calculate a third degree of subcooling;

[0050] calculating a third subcooling difference between the third subcooling degree and the third subcooling degree target value;

[0051] The opening of the third expansion valve is adjusted according to the numerical range of the third subcooling difference. The larger the upper limit of the numerical range of the third subcooling difference is, the larger the opening of the third expansion valve is.

[0052] In the above preferred technical solution of the triple heat pump system, a valve is provided on the fifth pipeline, and the control unit is further used for:

[0053] When the system performs heating operation, cooling operation or hot water operation, the valve and the second expansion valve are controlled to be closed.

[0054] In the above-mentioned preferred technical solution of the triple heat pump system, the first heat exchanger and the second heat exchanger are both single-stage heat exchangers.

[0055] A triple heat pump system provided in the present application includes three heat exchangers, so that the first heat exchanger and the second heat exchanger can be used as condensers at the same time to perform heating and hot water operations at the same time, or the first heat exchanger and the second heat exchanger can be used as a condenser and an evaporator respectively to perform heating and cooling operations at the same time. When cooling and heating are performed at the same time, the problems of large temperature changes of the heat exchanger, long waiting time, and easy failure caused by switching between cooling and heating modes can be avoided. Compared with the existing heat pump system with two heat exchangers, the simultaneous operation of three heat exchangers can increase the heat that can be utilized by the heat pump system, thereby improving the energy efficiency of the heat pump system. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0057] Figure 1is a schematic diagram of a triple heat pump system provided in an embodiment of the present application;

[0058] Figure 2 is a schematic diagram of another triple heat pump system provided in an embodiment of the present application;

[0059] Figure 3 It is a schematic diagram of a triple heat pump system with a single expansion valve provided in an embodiment of the present application;

[0060] Figure 4 It is a schematic diagram of another triple heat pump system with a single expansion valve provided in an embodiment of the present application;

[0061] Figure 5 A schematic diagram of another triple heat pump system with a single expansion valve provided in an embodiment of the present application;

[0062] Figure 6 It is a schematic diagram of a triple heat pump system with three expansion valves provided in an embodiment of the present application;

[0063] Figure 7 It is a schematic diagram of a double-valve triple heat pump system provided in an embodiment of the present application.

[0064] Reference numerals:

[0065] 101- a first heat exchanger;

[0066] 102- second heat exchanger;

[0067] 103 - third heat exchanger;

[0068] 104-suction line;

[0069] 105-exhaust pipe;

[0070] 106-first pipeline;

[0071] 107-second pipeline;

[0072] 108-third pipeline;

[0073] 201-four-way reversing valve;

[0074] 202- the fourth pipeline;

[0075] 203-Fifth pipeline;

[0076] 301-first expansion valve;

[0077] 401 - second expansion valve;

[0078] 501- third expansion valve;

[0079] 701-Valve.

[0080] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0081] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0082] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in sequences other than those illustrated or described herein, for example.

[0083] In the embodiments of the present application, the words "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0084] Existing heat pump systems generally include a compressor and two heat exchangers: an evaporator and a condenser. These two heat exchangers are generally located one outdoors and one indoors. The heat pump cycle is as follows: the compressor sucks in gaseous refrigerant from the evaporator, compresses it, and discharges the high-temperature and high-pressure refrigerant to the condenser. The refrigerant evaporates and absorbs heat in the evaporator, and condenses and releases heat in the condenser. Therefore, during cooling operation, the indoor heat exchanger is the evaporator, the refrigerant absorbs heat by evaporation to lower the indoor temperature, and the outdoor heat exchanger is the condenser, and the high-temperature refrigerant releases heat into the air by condensation; during heating operation, the outdoor heat exchanger is the evaporator, the refrigerant evaporates and absorbs heat from the outdoor air, and the indoor heat exchanger is the condenser, and the refrigerant condenses and releases heat to increase the indoor temperature.

[0085] However, since the existing heat pump system only includes one evaporator and one condenser, it cannot operate heating and hot water at the same time, nor can it operate cooling and heating at the same time. If the user switches between cooling and heating modes, the temperature of a single heat exchanger changes greatly, the waiting time is long, and it is easy to cause the heat pump system to malfunction.

[0086] In order to solve the above problems, the technical concept of the present application is: on the basis of the original two heat exchangers of the heat pump system, another heat exchanger is added, that is, including the first heat exchanger, the second heat exchanger, and the third heat exchanger, and one refrigerant inlet and outlet of the three heat exchangers are connected to each other through pipelines. The control unit switches the target heat exchanger to a condenser by connecting another refrigerant inlet and outlet of the target heat exchanger among the three heat exchangers with the exhaust pipeline of the compressor, and switches the target heat exchanger to an evaporator by connecting another refrigerant inlet and outlet of the target heat exchanger with the suction pipeline of the compressor.

[0087] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0088] The present application provides a triple heat pump system. Figure 1 is a schematic diagram of a triple heat pump system provided in an embodiment of the present application, such as Figure 1 As shown, the system includes:

[0089] The compressor, the first heat exchanger 101, the second heat exchanger 102, and the third heat exchanger 103, the compressor sucks in the refrigerant through the suction pipe 104 and discharges the refrigerant through the exhaust pipe 105, a refrigerant inlet and outlet of the first heat exchanger 101 is connected to each other through the first pipe 106, a refrigerant inlet and outlet of the second heat exchanger 102 is connected to each other through the second pipe 107, and a refrigerant inlet and outlet of the third heat exchanger 103 is connected to each other through the third pipe 108;

[0090] The system further comprises a control unit, which is configured to:

[0091] Connect another refrigerant inlet and outlet of the target heat exchanger among the first heat exchanger 101, the second heat exchanger 102, and the third heat exchanger 103 to the suction pipeline 104 to switch the target heat exchanger to an evaporator;

[0092] The other refrigerant inlet and outlet of the target heat exchanger is connected to the exhaust pipe 105 to switch the target heat exchanger to a condenser.

[0093] It should be noted that Figure 1The connection mode of the first heat exchanger 101, the second heat exchanger 102, the third heat exchanger 103 and the suction pipeline 104, the exhaust pipeline 105 shown is one of the multiple connection modes of the first heat exchanger 101, the second heat exchanger 102, the third heat exchanger 103 and the suction pipeline 104, the exhaust pipeline 105. In practical applications, the other refrigerant inlet and outlet of the three heat exchangers can be connected to the suction pipeline 104 or the exhaust pipeline 105 to switch the evaporator-condenser, as long as there is at least one evaporator and one condenser in the system. The control unit can switch the connection between the first heat exchanger 101, the second heat exchanger 102, the third heat exchanger 103 and the suction pipeline 104, the exhaust pipeline 105 by controlling the action of the mechanical structure.

[0094] In this embodiment, when the other refrigerant inlet and outlet of any two heat exchangers among the first heat exchanger 101, the second heat exchanger 102, and the third heat exchanger 103 are connected to the exhaust pipe 105, and the other refrigerant inlet and outlet of the remaining heat exchanger are connected to the suction pipe 104, since the system includes two condensers and one evaporator, the two condensers can perform heating and hot water operations at the same time, and the other evaporator performs heat exchange with outdoor air; or one condenser operates heating or hot water, one evaporator operates cooling, and one condenser performs heat exchange with outdoor air. It can be seen that the three-heat exchanger design of the present application can perform heating and cooling operations at the same time. When the user needs to cool and heat at the same time, there is no need to wait for a long time. The temperature of a single heat exchanger is relatively stable, which reduces the probability of failure.

[0095] In addition, the three heat exchangers work simultaneously, which can effectively utilize more heat than the two heat exchangers in the existing heat pump system. Therefore, the triple heat pump system provided in this embodiment is more energy efficient than the existing two-heat pump system.

[0096] In a possible embodiment of the present application, the control unit is further used for:

[0097] Connect the other refrigerant inlet and outlet of the first heat exchanger 101 and the other refrigerant inlet and outlet of the second heat exchanger 102 to the exhaust pipe 105, and connect the other refrigerant inlet and outlet of the third heat exchanger 103 to the suction pipe 104, so that the system can perform heating operation and hot water operation at the same time;

[0098] The other refrigerant inlet and outlet of the first heat exchanger 101 is connected to the suction pipe 104, and the other refrigerant inlet and outlet of the third heat exchanger 103 and the other refrigerant inlet and outlet of the second heat exchanger 102 are connected to the exhaust pipe 105, so that the system can perform cooling and heating operations at the same time.

[0099] In this embodiment, the third heat exchanger 103 can be an outdoor heat exchanger with a fan, and the third heat exchanger 103 performs heat exchange with outdoor air. The first heat exchanger 101 and the second heat exchanger 102 are indoor heat exchangers that play a role in making hot water or adjusting indoor temperature.

[0100] Optionally, the first heat exchanger 101 and the second heat exchanger 102 are both primary heat exchangers, that is, the refrigerant directly exchanges heat with the water or indoor air used by the user. Existing heat pump systems generally have secondary heat exchangers, that is, the refrigerant first exchanges heat with water, and the water after the heat exchange is then exchanged with the water or indoor air used by the user. In this embodiment, the primary heat exchange of the first heat exchanger 101 and the second heat exchanger 102 has less heat loss than the secondary heat exchange.

[0101] In a possible embodiment of the present application, another triple heat pump system is provided. Figure 2 is another schematic diagram of a triple heat pump system provided in an embodiment of the present application, such as Figure 2 As shown, the system further includes a four-way reversing valve 201, the exhaust pipeline 105 is connected to the first refrigerant inlet and outlet of the four-way reversing valve 201, the suction pipeline 104 is connected to the second refrigerant inlet and outlet of the four-way reversing valve 201, another refrigerant inlet and outlet of the third heat exchanger 103 is connected to the third refrigerant inlet and outlet of the four-way reversing valve 201, and another refrigerant inlet and outlet of the first heat exchanger 101 is connected to the fourth refrigerant inlet and outlet of the four-way reversing valve 201 through the fourth pipeline 202;

[0102] Another refrigerant inlet and outlet of the second heat exchanger 102 is connected to the exhaust pipe 105 through the fifth pipe 203;

[0103] The control unit is specifically used for:

[0104] Control the reversing of the four-way reversing valve 201 to connect the other refrigerant inlet and outlet of the third heat exchanger 103 with the exhaust pipe 105 to switch the third heat exchanger 103 to a condenser, and connect the other refrigerant inlet and outlet of the first heat exchanger 101 with the suction pipe 104 to switch the first heat exchanger 101 to an evaporator;

[0105] Control the reversing of the four-way reversing valve 201 to connect the other refrigerant inlet and outlet of the third heat exchanger 103 with the suction line 104 to switch the third heat exchanger 103 to an evaporator, and connect the other refrigerant inlet and outlet of the first heat exchanger 101 with the exhaust line 105 to switch the first heat exchanger 101 to a condenser.

[0106] In this embodiment, the control unit switches the three heat exchangers to evaporators or condensers by controlling the four-way reversing valve 201 .

[0107] In a possible embodiment of the present application, a triple heat pump system with a single expansion valve is provided. Figure 3Schematic diagram of a triple heat pump system with a single expansion valve provided in an embodiment of the present application. Figure 3 The first pipeline 106 is shown to be provided with a first expansion valve 301. In this embodiment, the control unit executes different control strategies on the first expansion valve 301 according to whether the system performs heating and cooling operations simultaneously or heating and hot water operations simultaneously.

[0108] In the first aspect, the control unit in this embodiment is also used for:

[0109] If the system performs heating operation and cooling operation at the same time, the refrigerant temperatures at the two refrigerant inlet and outlet of the first heat exchanger 101 are detected, and the opening degree of the first expansion valve 301 is adjusted according to the refrigerant temperatures at the two refrigerant inlet and outlet of the first heat exchanger 101;

[0110] Optionally, the control unit is specifically used for:

[0111] The first superheat degree is calculated according to the first superheat degree calculation formula. The first superheat degree calculation formula is:

[0112] SH1=T g1 -T l1

[0113] Among them, SH1 is the first superheat, T l1 is the first refrigerant temperature of the refrigerant inlet and outlet of the first heat exchanger 101 connected to the first pipeline 106, T g1 is the refrigerant temperature of another refrigerant inlet and outlet of the first heat exchanger 101;

[0114] It should be noted that when the system performs heating and cooling operations at the same time, the first heat exchanger 101 is an evaporator, and the fourth pipeline 202 is connected to the suction pipeline 104, that is, the refrigerant enters the first heat exchanger 101 from the first pipeline 106, and flows out of the first heat exchanger 101 from another refrigerant inlet and outlet of the first heat exchanger 101. According to the first superheat calculation formula, it can be known that SH1 reflects how much heat the refrigerant takes away through the first heat exchanger 101. The higher the first superheat, the more heat the refrigerant takes away through the first heat exchanger 101.

[0115] calculating a first superheat difference between a first superheat and a first superheat target value;

[0116] The opening of the first expansion valve 301 is adjusted according to the numerical range of the first superheat difference. The larger the upper limit of the numerical range of the first superheat difference is, the larger the opening of the first expansion valve 301 is.

[0117] The first superheat degree is subtracted from the first superheat degree target value to obtain the first superheat degree difference. If the first superheat degree difference is a positive number, it means that the first superheat degree is too high. A high first superheat degree may cause a high compressor exhaust temperature. The reason for the high first superheat degree is that the refrigerant flow rate flowing into the first heat exchanger 101 is too small and the heat absorbed by the unit refrigerant is too much. Therefore, the opening of the first expansion valve 301 is increased to increase the refrigerant flow rate entering the first heat exchanger 101, thereby reducing the first superheat degree.

[0118] When the cooling operation and the heating operation are performed simultaneously, the opening degree of the first expansion valve 301 can be calculated by a preset value × a first superheat difference × a preset step length, so as to achieve accurate adjustment of the opening degree according to the first superheat, for example, it can be:

[0119] When the first superheat difference is ≥2, the first expansion valve 301 is opened by 2×the first superheat difference×the preset step size; when the first superheat difference is ≤-2, the first expansion valve 301 is closed by 2×the first superheat difference×the preset step size; when -2<the first superheat difference<2, the opening of the first expansion valve 301 remains unchanged.

[0120] In a second aspect, the control unit in this embodiment is also used for:

[0121] If the system performs heating operation and hot water heating operation at the same time, the refrigerant saturation temperature of the exhaust pipe 105 and the first refrigerant temperature of the refrigerant inlet and outlet connected to the first heat exchanger 101 and the first pipe 106 are detected, and the opening of the first expansion valve 301 is adjusted according to the difference between the refrigerant saturation temperature of the exhaust pipe 105 and the first refrigerant temperature.

[0122] The saturation temperature is the temperature when the liquid and vapor are in a dynamic equilibrium state, that is, in a saturated state. When the saturation temperature is constant, the saturation pressure is also constant; conversely, when the saturation pressure is constant, the saturation temperature is also constant. Therefore, the saturation temperature of the refrigerant in the exhaust pipeline 105 can be obtained by measuring the pressure of the refrigerant in the exhaust pipeline 105. Specifically, a high-pressure switch can be set in the exhaust pipeline 105 to measure the refrigerant pressure of the exhaust pipeline 105.

[0123] It should be noted that if the system is simultaneously performing heating operation and hot water operation, the first heat exchanger 101 and the second heat exchanger 102 are both condensers, and the exhaust gas of the compressor passes through the exhaust pipe 105 and then through the fourth pipe 202 to enter the first heat exchanger 101, and then flows out from another refrigerant inlet and outlet of the first heat exchanger 101 through the first pipe 106. The refrigerant flowing through the first heat exchanger 101 will condense and release heat. According to the definition of saturation temperature, it can be understood that the difference between the saturation temperature of the refrigerant in the exhaust pipe 105 and the temperature of the first refrigerant reflects how much heat is released through the condensation process when the refrigerant flows through the first heat exchanger 101 after the temperature is lower than the saturation temperature, which is the critical point of condensation. The larger the difference, the more heat is released by the unit refrigerant. Generally speaking, if the difference is too high, it means that the unit refrigerant releases too much heat to reach the temperature set by the user, and the heating capacity of the heat pump system may be insufficient. Therefore, the opening of the first expansion valve 301 can be increased to increase the refrigerant flow entering the first heat exchanger 101, thereby improving the heat exchange capacity of the first heat exchanger 101.

[0124] Optionally, the control unit is specifically used for:

[0125] The first degree of subcooling is calculated by subtracting the first refrigerant temperature from the refrigerant saturation temperature of the exhaust pipe 105;

[0126] Calculating a first subcooling degree difference between the first subcooling degree and the first subcooling degree target value;

[0127] The opening of the first expansion valve 301 is adjusted according to the numerical range of the first subcooling difference. The larger the upper limit of the numerical range of the first subcooling difference is, the larger the opening of the first expansion valve 301 is.

[0128] When the refrigeration operation and the cooling water operation are performed simultaneously, the opening degree of the first expansion valve 301 can be calculated by a preset value × a first subcooling difference × a preset step length, so as to achieve accurate adjustment of the opening degree according to the first subcooling degree, for example, it can be:

[0129] When the first subcooling difference is ≥2, the first expansion valve 301 is opened by 2×the first subcooling difference×the preset step size; when the first subcooling difference is ≤-2, the first expansion valve 301 is closed by 2×the first subcooling difference×the preset step size; when -2<the first subcooling difference<2, the opening of the first expansion valve 301 remains unchanged.

[0130] In a possible embodiment of the present application, another triple heat pump system with a single expansion valve is provided. Figure 4 Schematic diagram of another triple heat pump system with a single expansion valve provided in an embodiment of the present application. Figure 4 As shown, the second pipeline 107 is provided with a second expansion valve 401, and the control unit is also used for:

[0131] Detecting the refrigerant saturation temperature of the exhaust pipe 105, and detecting the second refrigerant temperature of the refrigerant inlet and outlet communicating between the second heat exchanger 102 and the second pipe 107;

[0132] Subtract the second refrigerant temperature from the refrigerant temperature of the exhaust pipe 105 to calculate the second subcooling degree;

[0133] like Figure 4 As shown, a refrigerant inlet and outlet of the second heat exchanger 102 is connected to the exhaust pipe 105 through the fifth pipe 203, so the second heat exchanger 102 is a condenser, and the compressor exhaust enters the second heat exchanger 102 through the fifth pipe 203 and flows out of the second heat exchanger 102 from the second pipe 107. The relevant principle of the second subcooling is equivalent to the first subcooling, and this embodiment will not be repeated here.

[0134] Calculating a second subcooling degree difference between the second subcooling degree and the second subcooling degree target value;

[0135] The opening of the second expansion valve 401 is adjusted according to the numerical range of the second subcooling difference. The larger the upper limit of the numerical range of the second subcooling difference is, the larger the opening of the second expansion valve 401 is.

[0136] The opening degree of the second expansion valve 401 can be calculated by a preset value×a second subcooling difference×a preset step length, so as to achieve accurate adjustment of the opening degree according to the second subcooling degree, for example, it can be:

[0137] When the second subcooling difference is ≥2, the second expansion valve 401 is opened by 2×the second subcooling difference×the preset step size; when the second subcooling difference is ≤-2, the second expansion valve 401 is closed by 2×the second subcooling difference×the preset step size; when -2<the second subcooling difference<2, the opening of the second expansion valve 401 remains unchanged.

[0138] In a possible embodiment of the present application, another triple heat pump system with a single expansion valve is provided. Figure 5 A schematic diagram of a triple heat pump system with a single expansion valve provided in an embodiment of the present application is shown in FIG. Figure 5 As shown, the third pipeline 108 is provided with a third expansion valve 501. In this embodiment, the control unit executes different control strategies on the third expansion valve 501 according to whether the system performs heating and cooling operations simultaneously or heating and hot water operations simultaneously.

[0139] First, if the system performs heating operation and hot water operation at the same time, the control unit is also used to:

[0140] The opening degree of the third expansion valve 501 is adjusted according to the suction superheat of the compressor;

[0141] Optionally, if the system performs heating operation and hot water operation at the same time, the control unit is specifically used to:

[0142] Detecting the refrigerant temperature of the suction pipeline 104 and the refrigerant saturation temperature of the suction pipeline 104;

[0143] By providing a temperature sensor in the air intake pipeline 104, the refrigerant temperature in the air intake pipeline 104 can be measured. A low-pressure switch can be provided in the air intake pipeline 104, and by measuring the pressure of the refrigerant at the low-pressure switch, the refrigerant saturation temperature in the air intake pipeline 104 can be calculated. Since the refrigerant evaporates and absorbs heat in the third heat exchanger 103, the refrigerant temperature in the air intake pipeline 104 is higher than the refrigerant saturation temperature in the air intake pipeline 104.

[0144] The suction superheat is calculated by subtracting the saturated temperature of the refrigerant in the suction pipeline 104 from the refrigerant temperature in the suction pipeline 104;

[0145] Calculate the suction superheat difference between the suction superheat and the suction superheat target value;

[0146] The opening of the third expansion valve 501 is adjusted according to the numerical range of the suction superheat difference. The larger the upper limit of the numerical range of the suction superheat difference is, the larger the opening of the third expansion valve 501 is.

[0147] It should be noted that if the system is in heating operation and hot water operation at the same time, the third heat exchanger 103 is an evaporator, and a refrigerant inlet and outlet of the third heat exchanger 103 is connected to the suction pipeline 104. The compressor sucks the refrigerant gas from the third heat exchanger 103 from the suction pipeline 104, compresses it and discharges it to the exhaust pipeline 105. Therefore, the higher the temperature of the refrigerant sucked into the compressor, the higher the exhaust temperature of the compressor. The suction superheat of the compressor reflects the difference between the actual temperature of the refrigerant sucked into the compressor and the saturation temperature. The suction superheat of the compressor is high, indicating that the unit refrigerant absorbs too much heat through evaporation in the third heat exchange, which is caused by insufficient refrigerant flow entering the third heat exchanger 103. Therefore, it is necessary to adjust the opening of the third expansion valve 501 according to the suction superheat to adjust the suction superheat of the compressor. The ultimate goal is to keep the exhaust temperature of the compressor within a reasonable range.

[0148] When the heating operation and the hot water operation are performed simultaneously, the opening degree of the third expansion valve 501 can be calculated by a preset value × a suction superheat difference × a preset step length, so as to achieve accurate adjustment of the opening degree according to the suction superheat, for example, it can be:

[0149] When the intake superheat difference is ≥2, the third expansion valve 501 is opened by 2×the intake superheat difference×the preset step size; when the intake superheat difference is ≤-2, the third expansion valve 501 is closed by 2×the intake superheat difference×the preset step size; when -2<the intake superheat difference<2, the opening of the third expansion valve 501 remains unchanged.

[0150] Secondly, if the system performs heating and cooling operations at the same time, the refrigerant saturation temperature of the exhaust pipe 105 and the third refrigerant temperature of the refrigerant inlet and outlet connected to the third heat exchanger 103 and the third pipe 108 are detected, and the opening of the third expansion valve 501 is adjusted according to the difference between the saturation temperature of the exhaust pipe 105 and the third refrigerant temperature.

[0151] Optionally, the control unit is specifically used for:

[0152] If the system performs heating operation and cooling operation at the same time, the refrigerant saturation temperature and the third refrigerant temperature of the exhaust pipe 105 are detected;

[0153] The third degree of subcooling is calculated by subtracting the third refrigerant temperature from the refrigerant saturation temperature of the exhaust pipe 105;

[0154] Calculate a third subcooling degree difference between the third subcooling degree and the third subcooling degree target value;

[0155] The opening of the third expansion valve 501 is adjusted according to the numerical range of the third subcooling difference. The larger the upper limit of the numerical range of the third subcooling difference is, the larger the opening of the third expansion valve 501 is.

[0156] It should be noted that when the system is performing heating and cooling operations at the same time, the third heat exchanger 103 is a condenser, and a refrigerant inlet and outlet of the third heat exchanger 103 is connected to the exhaust pipe 105. The relevant principle of the third subcooling is equivalent to the first subcooling, and this embodiment will not be repeated here.

[0157] When the cooling operation and the heating operation are performed simultaneously, the opening degree of the third expansion valve 501 can be calculated by a preset value × a third subcooling difference × a preset step length, so as to achieve accurate adjustment of the opening degree according to the third subcooling degree, for example, it can be:

[0158] When the third subcooling difference is ≥2, the third expansion valve 501 is opened by 2×the third subcooling difference×the preset step size; when the third subcooling difference is ≤-2, the third expansion valve 501 is closed by 2×the third subcooling difference×the preset step size; when -2<the third subcooling difference<2, the opening of the third expansion valve 501 remains unchanged.

[0159] In a possible embodiment of the present application, a triple heat pump system with three expansion valves is provided. Figure 6 Schematic diagram of a triple heat pump system with three expansion valves provided in an embodiment of the present application. Figure 6 As shown, the heat pump system is provided with a first expansion valve 301, a second expansion valve 401, and a third expansion valve 501. During operation, the three expansion valves are controlled simultaneously according to corresponding control logics so that the heat pump system can achieve the best heat exchange capacity. The corresponding control logic is the same as the above embodiment, and this embodiment will not be repeated here.

[0160] In a possible embodiment of the present application, when the system is performing heating operation or cooling operation, the connection between the second heat exchanger 102 and the system is disconnected, and the opening of the first expansion valve 301 is adjusted according to the numerical range of the first superheat difference. The larger the upper limit value of the numerical range of the first superheat difference, the larger the opening of the first expansion valve 301.

[0161] When the system is in heating operation, the first heat exchanger 101 is a condenser, and a refrigerant inlet and outlet of the first heat exchanger 101 is connected to the exhaust pipeline 105. The refrigerant flows into the first heat exchanger 101 from the exhaust pipeline 105 through the fourth pipeline 202, and flows out of the first heat exchanger 101 from the first pipeline 106. At this time, the first superheat reflects the heat released by the refrigerant flowing through the first heat exchanger 101; when the system is in cooling operation, the first heat exchanger 101 is an evaporator, and a refrigerant inlet and outlet of the first heat exchanger 101 is connected to the suction pipeline 104. The refrigerant is sucked into the compressor from the fourth pipeline 202 through the suction pipeline 104, and is discharged to the third heat exchanger 103 through the exhaust pipeline 105 after compression. After flowing out of the third heat exchanger 103, the refrigerant passes through the third pipeline 108 and the first pipeline 106 in sequence to enter the first heat exchanger 101. Therefore, when the system is in cooling operation, the first superheat reflects the heat taken away by the refrigerant flowing through the first heat exchanger 101.

[0162] Therefore, it can be understood that no matter the system is running heating or cooling alone, the first superheat in this embodiment reflects whether the heat exchange capacity of the first heat exchanger 101 is sufficient. A high first superheat indicates that too much heat is released or absorbed by a unit of refrigerant after flowing through the first heat exchanger 101, which is caused by insufficient refrigerant flow into the first heat exchanger 101. Therefore, by increasing the opening of the first expansion valve 301, the first superheat can be reduced.

[0163] In this embodiment, the relevant control logic for adjusting the first expansion valve 301 according to the first superheat is equivalent to that in the above embodiment, and this embodiment will not be described in detail here.

[0164] In a possible embodiment of the present application, a double-valve triple heat pump system is provided. Figure 7 Schematic diagram of a double-valve triple heat pump system provided in an embodiment of the present application, such as Figure 7 As shown, the fifth pipeline 203 is provided with a valve 701, the second pipeline 107 is provided with a second expansion valve 401, and the control unit is also used for:

[0165] When the system is in heating operation, cooling operation or hot water operation, the control valve 701 and the second expansion valve 401 are closed.

[0166] When the valve 701 and the second expansion valve 401 are closed, the connection between the second heat exchanger 102 and the heat pump system is disconnected, so that the first heat exchanger 101 performs heating or cooling operation.

[0167] Optionally, the valve 701 may be a solenoid valve.

[0168] In addition, in this embodiment, the heat pump system may also be provided with a first expansion valve 301 and a third expansion valve 501 to adjust the heat exchange capacity of the heat pump system.

[0169] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments, and the above embodiments are only used to illustrate the technical solution of the present application rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A triple heat pump system, characterized in that: The system comprises: A compressor, a first heat exchanger, a second heat exchanger, and a third heat exchanger, wherein the compressor inhales refrigerant through an air intake pipeline and discharges refrigerant through an air discharge pipeline, a refrigerant inlet and outlet of the first heat exchanger is connected to each other through a first pipeline, a refrigerant inlet and outlet of the second heat exchanger is connected to each other through a second pipeline, and a refrigerant inlet and outlet of the third heat exchanger is connected to each other through a third pipeline; The system further comprises a control unit, which is configured to: Connecting another refrigerant inlet and outlet of the target heat exchanger among the first heat exchanger, the second heat exchanger and the third heat exchanger to the air intake pipeline to switch the target heat exchanger to an evaporator; The other refrigerant inlet and outlet of the target heat exchanger is connected to the exhaust pipeline to switch the target heat exchanger to a condenser.

2. The system according to claim 1, characterized in that The control unit is also used for: Connecting another refrigerant inlet and outlet of the first heat exchanger and another refrigerant inlet and outlet of the second heat exchanger to the exhaust pipe, and connecting another refrigerant inlet and outlet of the third heat exchanger to the suction pipe, so that the system can perform heating operation and hot water operation at the same time; Connect another refrigerant inlet and outlet of the first heat exchanger to the intake pipe, and connect another refrigerant inlet and outlet of the third heat exchanger and another refrigerant inlet and outlet of the second heat exchanger to the exhaust pipe, so that the system can perform cooling and heating operations simultaneously.

3. The system according to claim 1, characterized in that The system further includes a four-way reversing valve, the exhaust pipeline is connected to a first refrigerant inlet and outlet of the four-way reversing valve, the suction pipeline is connected to a second refrigerant inlet and outlet of the four-way reversing valve, another refrigerant inlet and outlet of the third heat exchanger is connected to a third refrigerant inlet and outlet of the four-way reversing valve, and another refrigerant inlet and outlet of the first heat exchanger is connected to a fourth refrigerant inlet and outlet of the four-way reversing valve through a fourth pipeline; Another refrigerant inlet and outlet of the second heat exchanger is connected to the exhaust pipeline through a fifth pipeline; The control unit is specifically used for: Controlling the reversing of the four-way reversing valve to connect another refrigerant inlet and outlet of the third heat exchanger with the exhaust pipeline to switch the third heat exchanger into a condenser, and connecting another refrigerant inlet and outlet of the first heat exchanger with the suction pipeline to switch the first heat exchanger into an evaporator; Control the reversing of the four-way reversing valve to connect the other refrigerant inlet and outlet of the third heat exchanger with the intake pipeline to switch the third heat exchanger to an evaporator, and connect the other refrigerant inlet and outlet of the first heat exchanger with the exhaust pipeline to switch the first heat exchanger to a condenser.

4. The system according to claim 1, characterized in that The first pipeline is provided with a first expansion valve, and the control unit is further used for: If the system performs heating operation and cooling operation at the same time, detecting the refrigerant temperatures at two refrigerant inlet and outlet of the first heat exchanger, and adjusting the opening of the first expansion valve according to the refrigerant temperatures at two refrigerant inlet and outlet of the first heat exchanger; If the system performs heating operation and hot water heating operation at the same time, the exhaust pipeline refrigerant saturation temperature and the first refrigerant temperature of the refrigerant inlet and outlet connected to the first heat exchanger and the first pipeline are detected, and the opening of the first expansion valve is adjusted according to the difference between the exhaust pipeline refrigerant saturation temperature and the first refrigerant temperature.

5. The system according to claim 4, characterized in that The control unit is specifically used for: The first superheat is calculated according to a first superheat calculation formula, which is: SH1=T g1 -T l1 Wherein, SH1 is the first superheat, T l1 is the first refrigerant temperature of the refrigerant inlet and outlet of the first heat exchanger connected to the first pipeline, T g1 is the refrigerant temperature of another refrigerant inlet and outlet of the first heat exchanger; calculating a first superheat difference between the first superheat and the first superheat target value; The first expansion valve opening is adjusted according to the numerical range of the first superheat difference. The larger the upper limit of the numerical range of the first superheat difference is, the larger the first expansion valve opening is.

6. The system according to claim 4, characterized in that The control unit is also used for: If the system performs heating operation and hot water operation at the same time, detecting the exhaust pipe refrigerant saturation temperature and the first refrigerant temperature; Calculate a first degree of subcooling by subtracting the first refrigerant temperature from the exhaust pipe refrigerant saturation temperature; calculating a first subcooling difference between the first subcooling degree and the first subcooling degree target value; The opening of the first expansion valve is adjusted according to the numerical range of the first subcooling difference. The larger the upper limit of the numerical range of the first subcooling difference is, the larger the opening of the first expansion valve is.

7. The system according to claim 5, characterized in that When the system is in heating operation or cooling operation, the connection between the second heat exchanger and the system is disconnected, and the opening of the first expansion valve is adjusted according to the numerical range of the first superheat difference. The larger the upper limit value of the numerical range of the first superheat difference is, the larger the opening of the first expansion valve is.

8. The system according to claim 3, characterized in that The second pipeline is provided with a second expansion valve, and the control unit is further used for: detecting the saturated temperature of the refrigerant in the exhaust pipeline, and detecting the second refrigerant temperature of the refrigerant inlet and outlet of the second heat exchanger connected to the second pipeline; Subtracting the second refrigerant temperature from the exhaust pipe refrigerant temperature to calculate a second degree of subcooling; calculating a second subcooling difference between the second subcooling degree and the second subcooling degree target value; The opening of the second expansion valve is adjusted according to the numerical range of the second subcooling difference. The larger the upper limit of the numerical range of the second subcooling difference is, the larger the opening of the second expansion valve is.

9. The system according to claim 1, characterized in that The third pipeline is provided with a third expansion valve, and the control unit is further used for: If the system performs heating operation and hot water operation at the same time, adjusting the opening of the third expansion valve according to the suction superheat of the compressor; If the system performs heating and cooling operations simultaneously, the exhaust pipeline refrigerant saturation temperature and the third refrigerant temperature of the refrigerant inlet and outlet connected to the third heat exchanger and the third pipeline are detected, and the opening of the third expansion valve is adjusted according to the difference between the exhaust pipeline saturation temperature and the third refrigerant temperature.

10. The system according to claim 9, characterized in that The control unit is specifically used for: If the system performs heating operation and hot water operation at the same time, detecting the refrigerant temperature of the suction pipeline and the saturation temperature of the refrigerant of the suction pipeline; Calculate the suction superheat by subtracting the suction pipeline refrigerant saturation temperature from the suction pipeline refrigerant temperature; calculating a suction superheat difference between the suction superheat and the suction superheat target value; The opening of the third expansion valve is adjusted according to the numerical range of the intake superheat difference. The larger the upper limit of the numerical range of the intake superheat difference is, the larger the opening of the third expansion valve is.

11. The system according to claim 9, characterized in that The control unit is specifically used for: If the system performs heating operation and cooling operation at the same time, detecting the exhaust pipe refrigerant saturation temperature and the third refrigerant temperature; Subtracting the third refrigerant temperature from the exhaust pipe refrigerant saturation temperature to calculate a third degree of subcooling; calculating a third subcooling difference between the third subcooling degree and the third subcooling degree target value; The opening of the third expansion valve is adjusted according to the numerical range of the third subcooling difference. The larger the upper limit of the numerical range of the third subcooling difference is, the larger the opening of the third expansion valve is.

12. The system according to claim 8, characterized in that The fifth pipeline is provided with a valve, and the control unit is further used for: When the system performs heating operation, cooling operation or hot water operation, the valve and the second expansion valve are controlled to be closed.

13. The system according to any one of claims 1 to 12, characterized in that: The first heat exchanger and the second heat exchanger both perform primary heat exchange.

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