Patent Publication Number: US-2023152014-A1

Title: Heat exchange system, air conditioning apparatus and control method for air conditioning apparatus

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present disclosure is a national phase application of International Application No. PCT/CN2020/138496, filed on Dec. 23, 2020, which claims priority to Chinese Patent Application No. 202010577788.8 and No. 202010577789.2 filed with China National Intellectual Property Administration on Jun. 23, 2020, the entireties of which are herein incorporated by reference. 
    
    
     FIELD 
     The present disclosure relates to the field of air conditioning, in particular, to heat exchange system, air conditioning apparatus and control method for air conditioning apparatus. 
     BACKGROUND 
     In the air-cooled heat pump unit, the refrigeration cycle and the heating cycle are inconsistent due to the inconsistent demand of the system for the amount of refrigerant, and the excess refrigerant needs to be stored in the accumulator for heating. This part of the refrigerant does not participate in the system circulation, preventing too much refrigerant from entering the system circulation and causing high pressure to rise, power to increase, and energy efficiency to decrease. 
       FIG.  1    is a diagram of a commonly used heat pump unit  100 ′, omitting irrelevant gas-liquid separators and oil separators. 
     When the unit is operating for cooling, the circulation process is compressor  110 ′→four-way valve  120 ′→fin type heat exchanger  130 ′→electronic expansion valve  140 ′→shell tube type heat exchanger  150 ′→four-way valve  120 ′→compressor  110 ′. When the unit is operating for heating, the circulation process is compressor  110 ′→four-way valve  120 ′→shell tube type heat exchanger  150 ′→electronic expansion valve  140 ′→fin type heat exchanger  130 ′→four-way valve  120 ′→compressor  110 ′. 
     For example, during the heating cycle, the connection between the accumulator  200 ′ and the shell tube is before the electronic expansion valve  140 ′ is throttled. Here is under high pressure, the pressure is higher than the internal pressure of the accumulator  200 ′, and the refrigerant will fill the accumulator  200 ′. During the refrigeration cycle, the connection between the accumulator  200 ′ and the shell tube is after the electronic expansion valve  140 ′ is throttled. Here is under the low pressure, the pressure is lower than the accumulator  200 ′, the refrigerant will automatically flow out from the accumulator  200 ′ and enter the system circulation. 
     However, when the heat pump unit  100 ′ is in the heating cycle, the accumulator  200 ′ is completely filled with refrigerant. After the capacity of the accumulator  200 ′ is determined, the amount of refrigerant stored is further fixed. Then, during the heating operation, the amount of refrigerant entering the system circulation is further determined, which cannot be adjusted according to the difference of the working conditions. It may lead to heavy load conditions, large refrigerant demand, insufficient liquid supply to the system, and reduced energy efficiency. For light load conditions, the demand for refrigerant is relatively small, resulting in increased power and reduced energy efficiency. 
     SUMMARY 
     The present disclosure aims to improve at least one of the problems existing in the prior art. 
     Embodiment of the present disclosure provides a heat exchange system. 
     Embodiment of the present disclosure provides an air conditioning apparatus. 
     Embodiment of the present disclosure provides a control method for air conditioning apparatus. 
     In view of this, according to an embodiment of the present disclosure, the present disclosure provides a heat exchange system, including a compressor, including an exhaust port and a suction port; a four-way valve, and a first end port of the four-way valve is communicated with the suction port, and a second end port of the four-way valve is communicated with the exhaust port; a first heat exchanger, and one end of the first heat exchanger is communicated with a third end port of the four-way valve; a throttle device, and one end of the throttle device is communicated with another end of the first heat exchanger; a second heat exchanger, and one end of the second heat exchanger is communicated with another end of the throttle device, and another end of the second heat exchanger is communicated with a fourth end port of the four-way valve; a fluid reservoir, including a first communication port and a second communication port, and the first communication port is communicated with the suction port, and the second communication port is communicated with one end of the second heat exchanger; a first valve body, being arranged on a flow path between the fluid reservoir and the compressor; a second valve body, being arranged on a flow path between the second communication port of the fluid reservoir and the throttle device; and a detection device, being used to detect the refrigerant amount for heat exchange cycle in the heat exchange system, and, when the heat exchange system operates in a heating condition, working states of the first valve body and the second valve body are controlled according to the refrigerant amount in the heat exchange system. 
     The heat exchange system provided by the present disclosure includes a refrigerant circuit consisting of a compressor, a four-way valve, a first heat exchanger, a throttle device, and a second heat exchanger. In addition, it further includes a fluid reservoir, a first valve body, and a second valve body. The fluid reservoir includes a first communication port and a second communication port, and one end of the first valve body is communicated to the first communication port, and another end of the first valve body is communicated to the suction port of the compressor. One end of the second valve body is communicated with the second communication port, and another end of the second valve body is communicated with the second heat exchanger. It further includes a detection device, which is used to detect the refrigerant amount for heat exchange cycle in the heat exchange system, that is, the refrigerant in the fluid reservoir does not enter the circuit to circulate and exchange heat, and this part of the refrigerant amount is not within the detection range of the detection device. Furthermore, when the heat exchange system operates under the heating condition, the working states of the first valve body and the second valve body are controlled according to the refrigerant amount for heat exchange system. Furthermore, it is possible to flexibly control the refrigerant amount of refrigerant in the fluid reservoir entering the heat exchange cycle, that is, the refrigerant amount for heat exchange cycle in the heat exchange system can be increased or decreased according to the actual situation, and to reduce the power of the heat exchange system and increase the energy efficiency of the heat exchange system. 
     For example, the heat exchange system can realize the cooling or heating of the heat exchange system by adjusting the communication state of the four-way valve. 
     When the heat exchange system is under heating condition, the refrigerant circulation path is compressor→four-way valve→second heat exchanger→throttle device→first heat exchanger→four-way valve→compressor. 
     When the heat exchange system is under cooling condition, the refrigerant circulation path is compressor→four-way valve→first heat exchanger→throttle device→second heat exchanger→four-way valve→compressor. 
     In the heating condition, the first valve body and the second valve body are closed or opened according to the refrigerant amount for heat exchange cycle in the heat exchange system, and the refrigerant in the fluid reservoir can enter the heat exchange cycle, or the refrigerant in the heat exchange cycle can enter the fluid reservoir, or keep the refrigerant amount in the fluid reservoir unchanged. Therefore, the on-demand access of the refrigerant to the heat exchange cycle is realized, and the refrigerant amount for the heat exchange cycle is always kept in an appropriate state, to reduce the power of the heat exchange system and improving the energy efficiency of the heat exchange system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments of the present disclosure will become apparent and readily understood from the description of embodiments in conjunction with the following drawings: 
         FIG.  1    shows a schematic structural diagram of a heat pump unit in the related art; 
         FIG.  2    shows a schematic structural diagram of a heat exchange system provided by an embodiment of the present disclosure; 
         FIG.  3    shows a flow chart of a control method for air conditioning apparatus provided by embodiments of the present disclosure; 
         FIG.  4    shows a flow chart of a control method for air conditioning apparatus provided by embodiments of the present disclosure; 
         FIG.  5    shows a partial flow chart of a control method for air conditioning apparatus provided by embodiments of the present disclosure; and 
         FIG.  6    shows a partial flow chart of a control method for air conditioning apparatus provided by embodiments of the present disclosure. 
     
    
    
     Wherein, the corresponding relationship between the reference signs and component names in  FIG.  1    is as follows: 
       100 ′ heat pump unit,  110 ′ compressor,  120 ′ four-way valve,  130 ′ fin type heat exchanger,  140 ′ electronic expansion valve,  150 ′ shell tube type heat exchanger,  200 ′ accumulator. 
     The corresponding relationship between the reference signs and component names in  FIG.  2    is as follows: 
       100  heat exchange system,  110  compressor,  112  exhaust port,  114  suction port,  120  four-way valve,  122  first end port,  124  second end port,  126  third end port,  128  fourth end port,  130  first heat exchanger,  140  throttle device,  150  second heat exchanger,  160  first valve body,  170  second valve body,  180  one-way valve,  190  fan,  200  fluid reservoir,  202  first communication port,  204  second communication port,  210  detection device. 
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Some embodiments of the present disclosure will be described in further detail with reference to the accompanying drawings and detailed description. It should be noted that the embodiments and features in the embodiments of the present disclosure may be combined with one another without conflicts. 
     In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure, but the present disclosure may be practiced otherwise than as described herein, and therefore, the protection scope of the present disclosure is not limited to the exemplary embodiments disclosed below. 
     A heat exchange system  100 , an air conditioning apparatus and a control method for air conditioning apparatus provided according to some embodiments of the present disclosure are described below with reference to  FIGS.  2  to  6   . 
     As shown in  FIG.  2   , according to an embodiment of the present disclosure, the present disclosure provides a heat exchange system  100 , including a circulation loop composed of a compressor  110 , a four-way valve  120 , a first heat exchanger  130 , a throttle device  140 , and a second heat exchanger  150 . Wherein, the first end port  122  of the four-way valve  120  is connected to the suction port  114  of the compressor  110 , the second end port  124  of the four-way valve  120  is connected to the exhaust port  112  of the compressor  110 . The third end port  126  of the four-way valve  120  is connected to the first heat exchanger  130 ; the fourth end port  128  of the four-way valve  120  is connected to the second heat exchanger  150 . The first heat exchanger  130  and the second heat exchanger  150  are further connected through the throttle device  140 . 
     Furthermore, by changing the communication state of the four-way valve  120 , the switching between cooling and heating of the heat exchange system  100  can be realized. For example, as shown in  FIG.  2   , when the four-way valve  120  works according to the hollow arrow, the heat exchange system  100  is in heating condition. The refrigerant circulation path is compressor  110 →four-way valve  120 →second heat exchanger  150 →throttle device  140 →first heat exchanger  130 →four-way valve  120 →compressor  110 ; when the four-way valve  120  works according to the solid arrow, the heat exchange system  100  is in cooling condition, the refrigerant circulation path is compressor  110 →four-way valve  120 →first heat exchanger  130 →throttle device  140 →second heat exchanger  150 →four-way valve  120 →compressor  110 . 
     The heat exchange system  100  provided by the present disclosure further includes a fluid reservoir  200 , a first valve body  160  and a second valve body  170 , and the fluid reservoir  200  comprises a first communication port  202  and a second communication port  204 . The first communication port  202  is communicated with the suction port  114  of the compressor  110  through the first valve body  160 ; the second communication port  204  is communicated with the second heat exchanger  150  through the second valve body  170 , and it further comprises a detection device  210  for detecting the refrigerant amount for heat exchange cycle in the heat exchange system  100 . In addition, when the heat exchange system  100  operates under heating conditions, the side of second heat exchanger  150  has high-pressure refrigerant. Since the refrigerant on the side of second heat exchanger  150  is in a high-pressure state, if the second valve body  170  is opened and the first valve body  160  is closed, the refrigerant for heat exchange cycle will enter the fluid reservoir  200 . If the first valve body  160  and the second valve body  170  are closed, the refrigerant amount in the fluid reservoir  200  and the refrigerant amount for heat exchange cycle remain unchanged. Moreover, the suction port  114  of the compressor  110  is in a low-pressure state, and if the first valve body  160  is opened and the second valve body  170  is closed, the refrigerant in the fluid reservoir  200  will enter the compressor  110  to perform a heat exchange cycle. 
     Based on the above principle, in heating condition, the first valve body  160  and the second valve body  170  are closed or opened according to the refrigerant amount for heat exchange cycle in the heat exchange system  100 , and the refrigerant in the fluid reservoir  200  can enter the heat exchange cycle, or the refrigerant in the heat exchange cycle can enter the fluid reservoir  200 , or keep the refrigerant amount in the fluid reservoir  200  unchanged. Therefore, the on-demand access of the refrigerant to the heat exchange cycle is realized, and the refrigerant amount for the heat exchange cycle is always kept in an appropriate state, to reduce the power of the heat exchange system  100  and improving the energy efficiency of the heat exchange system  100 . 
     Furthermore, by setting the first refrigerant amount threshold and the second refrigerant amount threshold, the first refrigerant amount threshold is less than the second refrigerant amount threshold. If the refrigerant amount for the heat exchange cycle in the heat exchange system  100  is less than the first refrigerant amount threshold, it means that the refrigerant amount for the heat exchange cycle in the heat exchange system  100  is insufficient. At this time, the first valve body  160  is opened, and the second valve body  170  is closed, and the refrigerant in the fluid reservoir  200  enters the compressor  110  under the influence of the compressor  110  suction port  114 , to increase the refrigerant amount for heat exchange in the heat exchange system  100 . 
     If the refrigerant amount for heat exchange cycle in the heat exchange system  100  is greater than or equal to the first refrigerant amount threshold and less than the second refrigerant amount threshold. It means that the refrigerant amount for heat exchange cycle in the heat exchange system  100  is appropriate. At this time, the first valve body  160  and the second valve body  170  are closed, and the refrigerant for heat exchange cycle in the heat exchange system  100  remains unchanged. 
     If the refrigerant amount for heat exchange cycle in the heat exchange system  100  is greater than or equal to the second refrigerant amount threshold. It means that the refrigerant amount for heat exchange cycle in the heat exchange system  100  is excessive. At this time, when the first valve body  160  is closed and the second valve body  170  is opened, the refrigerant for heat exchange cycle in the heat exchange system  100  can enter the fluid reservoir  200 , to reduce the refrigerant amount for heat exchange in the heat exchange system  100 . 
     As mentioned above, the refrigerant amount for heat exchange cycle in the heat exchange system  100  is dynamically controlled, and the refrigerant amount for heat exchange cycle in the heat exchange system  100  is always in an appropriate state. Therefore, the power of the heat exchange system  100  is reduced, and the energy efficiency of the heat exchange system  100  is improved. 
     More furthermore, both the first valve body  160  and the second valve body  170  are solenoid valves, and the working states of the first valve body  160  and the second valve body  170  can be controlled by a program. 
     Wherein, the fluid reservoir  200  may be an accumulator. 
     It should be noted that the first refrigerant amount threshold and the second refrigerant amount threshold can be set according to actual conditions such as the power of the compressor  110 , the total refrigerant amount in the heat exchange system  100 , and the heat exchange efficiency of the heat exchanger. 
     Furthermore, in the heat exchange system  100 , a gas-liquid separator and an oil separator are further connected, but both are not relevant to the present disclosure. Therefore, it will not be described here, and can be determine the connection mode of the gas-liquid separator and the oil separator according to related technologies. 
     For example, the heat exchange system  100  may be a heat pump unit. 
     In some embodiments, the detection device  210  comprises a liquid level sensor, being arranged at the second heat exchanger  150  for detecting the refrigerant liquid level in the second heat exchanger  150 . 
     In this embodiment, a first liquid level height threshold and a second liquid level height threshold may be set, and the first liquid level height threshold is less than the second liquid level height threshold. If the refrigerant amount for heat exchange in the heat exchange system  100  is insufficient, the liquid level in the second heat exchanger  150  will be lower than the first liquid level height threshold. If the refrigerant amount for heat exchange in the heat exchange system  100  is appropriate, then the liquid level in the second heat exchanger  150  will be greater than or equal to the first liquid level height threshold and less than the second liquid level height threshold. If the refrigerant amount for heat exchange in the heat exchange system  100  is insufficient, the liquid level in the second heat exchanger  150  will be greater than or equal to the second liquid level height threshold. This detection method is simple and effective, and easy to implement. 
     It is worth noting that the first liquid level height threshold and the second liquid level height threshold can be set according to the actual conditions such as the power of the compressor  110 , the total refrigerant amount in the heat exchange system  100  and the heat exchange efficiency of the heat exchanger. 
     In one embodiment, the detection device  210  comprises a pressure sensor, being arranged at the second heat exchanger  150 , for detecting the refrigerant pressure in the second heat exchanger  150 . 
     In this embodiment, a first pressure threshold and a second pressure threshold may be set, and the first pressure threshold is less than the second pressure threshold. If the refrigerant amount for heat exchange in the heat exchange system  100  is insufficient, the pressure in the second heat exchanger  150  will be less than the first pressure threshold. If the refrigerant amount for heat exchange in the heat exchange system  100  is appropriate, then the pressure in the second heat exchanger  150  will be greater than or equal to the first pressure threshold and less than the second pressure threshold. If the refrigerant amount for heat exchange in the heat exchange system  100  is insufficient, the pressure in the second heat exchanger  150  will be greater than or equal to the second pressure threshold. This detection method is simple and effective, and easy to implement. 
     It is worth noting that the first pressure threshold and the second pressure threshold can be set according to the actual conditions such as the power of the compressor  110 , the total refrigerant amount in the heat exchange system  100 , and the heat exchange efficiency of the heat exchanger. 
     As shown in  FIG.  2   , on the basis of any one of the embodiments, furthermore, the heat exchange system  100  further includes a one-way valve  180 . The one-way valve  180  is located on the flow path between the second communication port  204  of the fluid reservoir  200  and the second heat exchanger  150 , and the conduction direction of the one-way valve  180  is the direction from the second heat exchanger  150  to the fluid reservoir  200 . For example, the one-way valve  180  can be arranged on the flow path between the second communication port  204  of the fluid reservoir  200  and the second valve body  170 ; the one-way valve  180  can further be arranged on the flow path between the second valve body  170  and the second heat exchanger  150 . 
     In this embodiment, the guided conduction function of the one-way valve  180  is used, and the refrigerant entering the fluid reservoir  200  will not flow back to the side of second heat exchanger  150 , to ensure the recovery effect of the refrigerant on the side of second heat exchanger  150  and ensuring the antifreeze protection for the second heat exchanger  150 . 
     As shown in  FIG.  2   , on the basis of any one of the embodiments, furthermore, the first communication port  202  of the fluid reservoir  200  is communicated to the suction port  114  of the compressor  110  and the first end port  122  of the four-way valve  120  through a three-way pipeline. 
     In this embodiment, there is no need to set up another pipeline at the suction port  114  of the compressor  110 , and it is only necessary to use a three-way pipeline to access the fluid reservoir  200  at an appropriate position. Therefore, it is more conducive to the layout of pipelines, reducing the amount of pipelines and saving costs. 
     As shown in  FIG.  2   , on the basis of any one of the embodiments, furthermore, the second communication port  204  of the fluid reservoir  200  is connected with the throttle device  140  and the second heat exchanger  150  through a three-way pipeline. 
     In this embodiment, there is no need to set up another pipeline at the end port of the second heat exchanger  150 , and it is only necessary to use a three-way pipeline to access the fluid reservoir  200  at an appropriate position. Therefore, it is more conducive to the layout of pipelines, reducing the amount of pipelines and saving costs. 
     As shown in  FIG.  2   , on the basis of any one of the embodiments, furthermore, the first heat exchanger  130  adopts a fin type heat exchanger. 
     In the embodiment, the first heat exchanger  130  adopts a fin type heat exchanger, which is more conducive to the thermal circulation when the air flows between the first heat exchangers  130 , to facilitate the cooling or heating effect of the heat exchange system  100 . 
     As shown in  FIG.  2   , on the basis of any one of the embodiments, furthermore, the second heat exchanger  150  adopts a shell tube type heat exchanger. 
     In this embodiment, the second heat exchanger  150  adopts a shell tube type heat exchanger; For example, it can be a full liquid type shell tube type heat exchanger or a falling film type shell tube type heat exchanger. That is, the high heat transfer coefficient of the shell tube type heat exchanger is used to facilitate the heat exchange of the refrigerant, and the setting of the fluid reservoir  200  can protect the full liquid type shell tube type heat exchanger or the falling film type shell tube type heat exchanger. Thus, the risk of freezing tubes in full liquid type shell tube type heat exchanger or the falling film type shell tube type heat exchanger is avoided. 
     As shown in  FIG.  2   , on the basis of any one of the embodiments, furthermore, the heat exchange system  100  further includes a fan  190 , being located at the periphery of the second heat exchanger  150 , to supply air to the first heat exchanger  130 , and the mode of supplying air comprises suction or blowing. 
     In this embodiment, the fan  190  is used to transmit the cooling or heat generated by the first heat exchanger  130  to the target location, and the purpose of air conditioning. 
     The first valve body  160  and the second valve body  170  in any of the above embodiments can be normally closed or normally open according to actual needs. 
     On the basis of any one of the embodiments, the throttle device  140  comprises an electronic expansion valve. The electronic expansion valve is connected between the first heat exchanger  130  and the second heat exchanger  150 , and then the heat exchange effect can be adjusted by adjusting the opening of the electronic expansion valve. In addition, after the heat exchange system  100  operates in heating condition and stops, close the electronic expansion valve, and the high-pressure refrigerant can be intercepted on the side of second heat exchanger  150 . Therefore, the recovery effect of the fluid reservoir  200  on the refrigerant is improved, and the effect of the antifreeze protection on the second heat exchanger  150  is improved. 
     The heat exchange system  100  provided by the present disclosure comprises ten main components. That is a shell tube type heat exchanger, an accumulator, a compressor  110 , an electronic expansion valve, a fin type heat exchanger, a fan  190 , a four-way valve  120 , a first solenoid valve, a one-way valve  180 , and a second solenoid valve. 
     When the unit is operating for cooling, the circulation process is compressor  110 →four-way valve  120 →fin type heat exchanger→electronic expansion valve→shell tube type heat exchanger→four-way valve  120 →compressor  110 . 
     When the unit is operating for heating, the circulation process is compressor  110 →four-way valve  120 →shell tube type heat exchanger→electronic expansion valve→fin type heat exchanger→four-way valve  120 →compressor  110 . 
     The inlet of the accumulator is located between the electronic expansion valve and the shell tube type heat exchanger, the heating is operating, and the inlet is under high pressure. The outlet of the accumulator is connected to the suction port  114  of the compressor  110 , which is always under low pressure. 
     During heating operation, if the refrigerant amount in the shell tube is appropriate, close the first solenoid valve and the second solenoid valve. If the refrigerant in the shell tube is insufficient, open the first solenoid valve and close the second solenoid valve to discharge the refrigerant in the accumulator and enter the system circulation. If there is too much refrigerant in the shell tube, close the second solenoid valve, open the second solenoid valve, and discharge the refrigerant in the shell tube type heat exchanger into the accumulator. 
     During cooling operation, the demand of refrigerant increases, the entire refrigerant needs to be discharged from the accumulator. The actions are as follows: open the first solenoid valve, close the second solenoid valve, discharge the refrigerant in the accumulator, and enter the system circulation. 
     As shown in  FIG.  2   , according to an embodiment of the present disclosure, the present disclosure provides a heat exchange system  100 , including a circulation loop composed of a compressor  110 , a four-way valve  120 , a first heat exchanger  130 , a throttle device  140 , and a second heat exchanger  150 . Wherein, the first end port  122  of the four-way valve  120  is connected to the suction port  114  of the compressor  110 , the second end port  124  of the four-way valve  120  is connected to the exhaust port  112  of the compressor  110 . The third end port  126  of the four-way valve  120  is connected to the first heat exchanger  130 ; the fourth end port  128  of the four-way valve  120  is connected to the second heat exchanger  150 . The first heat exchanger  130  and the second heat exchanger  150  are further connected through the throttle device  140 . 
     Furthermore, by changing the communication state of the four-way valve  120 , the switching between cooling and heating of the heat exchange system  100  can be realized. For example, as shown in  FIG.  2   , when the four-way valve  120  works according to the hollow arrow, the heat exchange system  100  is in heating condition. The refrigerant circulation path is compressor  110 →four-way valve  120 →second heat exchanger  150 →throttle device  140 →first heat exchanger  130 →four-way valve  120 →compressor  110 ; when the four-way valve  120  works according to the solid arrow, the heat exchange system  100  is in cooling condition, the refrigerant circulation path is compressor  110 →four-way valve  120 →first heat exchanger  130 →throttle device  140 →second heat exchanger  150 →four-way valve  120 →compressor  110 . 
     The heat exchange system  100  provided by the present disclosure further includes a fluid reservoir  200 , a first valve body  160  and a second valve body  170 , and the fluid reservoir  200  comprises a first communication port  202  and a second communication port  204 . The first communication port  202  is communicated with the suction port  114  of the compressor  110  through the first valve body  160 ; the second communication port  204  is communicated with the second heat exchanger  150  through the second valve body  170 . Moreover, after the heat exchange system  100  is operating under heating conditions and stopped, a large amount of high-pressure refrigerant will remain on the side of second heat exchanger  150 , and the refrigerant on the side of second heat exchanger  150  is in a high-pressure state. At this time, by opening the second valve body  170  and closing the first valve body  160 , the refrigerant on the side of second heat exchanger  150  can be discharged into the fluid reservoir  200 , to realize the recovery of the high-pressure refrigerant on the side of second heat exchanger  150 . Since the refrigerant amount on the side of second heat exchanger  150  is reduced, the following problems are avoided: that is, due to a large amount of refrigerant remaining on the side of second heat exchanger  150 , the refrigerant is cooled on the side of second heat exchanger  150 , to cause the freezing tube of the second heat exchanger  150 . This provides antifreeze protection for the second heat exchanger  150  and improves the performance of the heat exchange system  100 . And after the heat exchange system  100  is restarted, the first heat exchanger  130  can be turned on, and the second heat exchanger  150  can be turned off, because the pressure at the suction port  114  of the compressor  110  is low, the refrigerant stored in the fluid reservoir  200  can be re-inhaled into the compressor  110 , and the refrigerant circulation can be continued to ensure the refrigerant amount for heat exchange cycle in the heat exchange system  100 . 
     Furthermore, both the first valve body  160  and the second valve body  170  are solenoid valves, and the working states of the first valve body  160  and the second valve body  170  can be controlled by a program. 
     In some embodiments, the throttle device  140  comprises an electronic expansion valve. The electronic expansion valve is connected between the first heat exchanger  130  and the second heat exchanger  150 , and then the heat exchange effect can be adjusted by adjusting the opening of the electronic expansion valve. In addition, after the heat exchange system  100  operates in heating condition and stops, close the electronic expansion valve, and the high-pressure refrigerant can be intercepted on the side of second heat exchanger  150 . Therefore, the recovery effect of the fluid reservoir  200  on the refrigerant is improved, and the effect of the antifreeze protection on the second heat exchanger  150  is improved. 
     As shown in  FIG.  2   , on the basis of any embodiments, furthermore, the heat exchange system  100  further includes a one-way valve  180 . The one-way valve  180  is located on the flow path between the second communication port  204  of the fluid reservoir  200  and the second heat exchanger  150 , and the conduction direction of the one-way valve  180  is the direction from the second heat exchanger  150  to the fluid reservoir  200 . For example, the one-way valve  180  can be arranged on the flow path between the second communication port  204  of the fluid reservoir  200  and the second valve body  170 ; the one-way valve  180  can further be arranged on the flow path between the second valve body  170  and the second heat exchanger  150 . 
     In this embodiment, the guided conduction function of the one-way valve  180  is used, and the refrigerant entering the fluid reservoir  200  will not flow back to the side of second heat exchanger  150 , to ensure the recovery effect of the refrigerant on the side of second heat exchanger  150  and ensuring the antifreeze protection for the second heat exchanger  150 . 
     As shown in  FIG.  2   , on the basis of any embodiments, the first communication port  202  of the fluid reservoir  200  is communicated to the suction port  114  of the compressor  110  and the first end port  122  of the four-way valve  120  through a three-way pipeline. 
     In this embodiment, there is no need to set up another pipeline at the suction port  114  of the compressor  110 , and it is only necessary to use a three-way pipeline to access the fluid reservoir  200  at an appropriate position. Therefore, it is more conducive to the layout of pipelines, reducing the amount of pipelines and saving costs. 
     As shown in  FIG.  2   , on the basis of any embodiments, furthermore, the second communication port  204  of the fluid reservoir  200  is connected with the throttle device  140  and the second heat exchanger  150  through a three-way pipeline. 
     In this embodiment, there is no need to set up another pipeline at the end port of the second heat exchanger  150 , and it is only necessary to use a three-way pipeline to access the fluid reservoir  200  at an appropriate position. Therefore, it is more conducive to the layout of pipelines, reducing the amount of pipelines and saving costs. 
     As shown in  FIG.  2   , on the basis of any embodiments, furthermore, the first heat exchanger  130  adopts a fin type heat exchanger. 
     In the embodiment, the first heat exchanger  130  adopts a fin type heat exchanger, which is more conducive to the thermal circulation when the air flows between the first heat exchangers  130 , to facilitate the cooling or heating effect of the heat exchange system  100 . 
     As shown in  FIG.  2   , on the basis of any embodiments, furthermore, the second heat exchanger  150  adopts a shell tube type heat exchanger. 
     In this embodiment, the second heat exchanger  150  adopts a shell tube type heat exchanger; For example, it can be a full liquid type shell tube type heat exchanger or a falling film type shell tube type heat exchanger. That is, the high heat transfer coefficient of the shell tube type heat exchanger is used to facilitate the heat exchange of the refrigerant, and the setting of the fluid reservoir  200  can protect the full liquid type shell tube type heat exchanger or the falling film type shell tube type heat exchanger. Thus, the risk of freezing tubes in full liquid type shell tube type heat exchanger or the falling film type shell tube type heat exchanger is avoided. 
     As shown in  FIG.  2   , on the basis of any embodiments, furthermore, the heat exchange system  100  further includes a fan  190 , being located at the periphery of the second heat exchanger  150 , to supply air to the first heat exchanger  130 , and the mode of supplying air comprises suction or blowing. 
     In this embodiment, the fan  190  is used to transmit the cooling or heat generated by the first heat exchanger  130  to the target location, and the purpose of air conditioning. 
     The first valve body  160  and the second valve body  170  in any of the above embodiments can be normally closed or normally open according to actual needs. 
     The heat exchange system  100  provided by the present disclosure comprises ten main components. That is a shell tube type heat exchanger, an accumulator  200 , a compressor  110 , an electronic expansion valve, a fin type heat exchanger, a fan  190 , a four-way valve  120 , a first solenoid valve, a one-way valve  180 , and a second solenoid valve. 
     When the system is operating for cooling, the circulation process is compressor  110 →four-way valve  120 →fin type heat exchanger→electronic expansion valve→shell tube type heat exchanger→four-way valve  120 →compressor  110 . 
     When the system is operating for heating, the circulation process is compressor  110 →four-way valve  120 →shell tube type heat exchanger→electronic expansion valve→fin type heat exchanger→four-way valve  120 →compressor  110 . 
     The inlet of the accumulator  200  is located between the electronic expansion valve and the shell tube type heat exchanger, the heating is operating, and the inlet is under high pressure. The outlet of the accumulator  200  is connected to the suction port  114  of the compressor  110 , which is always under low pressure. 
     Heating mode shutdown: after the compressor  110  stops, the electronic expansion valve is closed, the first solenoid valve is closed, the second solenoid valve is opened, and the refrigerant in the shell tube type heat exchanger flows through the second solenoid valve and the one-way valve  180 , and is discharged into the fluid reservoir  200 , and through the one-way valve  180  to prevent the refrigerant from flowing back to the shell tube type heat exchanger. 
     Wherein, the fluid reservoir may be an accumulator. 
     Furthermore, in the heat exchange system  100 , a gas-liquid separator and an oil separator are further connected, but both are not relevant to the present disclosure. Therefore, it will not be described here, and can determine the connection mode of the gas-liquid separator and the oil separator according to related technologies. 
     For example, the heat exchange system  100  may be a heat pump unit. 
     Furthermore, it further comprises a detection device  210 , being located at the second heat exchanger  150 , for detecting the refrigerant amount in the heat exchange system  100 , and to increase or decrease the refrigerant according to the actual situation to improve the energy efficiency of the heat exchange system  100 . 
     According to an embodiment of the present disclosure, the present disclosure provides an air conditioning apparatus, including the heat exchange system  100  as provided in any one of the above-mentioned embodiments. 
     The air conditioning apparatus provided by the present disclosure comprises the heat exchange system  100  provided in any one of the above-mentioned embodiments. Therefore, it has all the beneficial effects of the heat exchange system  100  as provided in any one of the above-mentioned embodiments, which are not repeated here one by one. 
       FIG.  3    shows a flow chart of a control method for air conditioning apparatus provided by one embodiment of the present disclosure. 
     As shown in  FIG.  3   , the specific process of the control method for air conditioning apparatus provided by an embodiment of the present disclosure is as follows: 
     Step  302 : acquiring, in the case of operating heating mode, the refrigerant amount for heat exchange cycle in the heat exchange system; 
     Step  304 : controlling, the working state of the first valve body and the second valve body according to the refrigerant amount. 
     The control method for air conditioning apparatus provided by the present disclosure, based on the air conditioning apparatus provided by any one of the above-mentioned embodiments, that is, when the four-way valve works according to the hollow arrow, when the air conditioning apparatus operates in heating mode, the refrigerant circulation path is, compressor→four-way valve→second heat exchanger→throttle device→first heat exchanger→four-way valve→compressor; when the four-way valve works according to the solid arrow, when the air conditioning apparatus operates in cooling mode, the refrigerant circulation path is, compressor→four-way valve→first heat exchanger→throttle device→second heat exchanger→four-way valve→compressor. 
     When the heat exchange system  100  operates under heating conditions, the side of second heat exchanger  150  has high-pressure refrigerant. Since the refrigerant on the side of second heat exchanger  150  is in a high-pressure state, if the second valve body  170  is opened and the first valve body  160  is closed, the refrigerant for heat exchange cycle will enter the fluid reservoir. If the first valve body and the second valve body are closed, the refrigerant amount in the fluid reservoir and the refrigerant amount for heat exchange cycle remain unchanged. Moreover, the suction port of the compressor is in a low-pressure state, and if the first valve body is opened and the second valve body is closed, the refrigerant in the fluid reservoir will enter the compressor to perform a heat exchange cycle. 
     Based on the above principle, in heating condition, the first valve body and the second valve body are closed or opened according to the refrigerant amount for heat exchange cycle in the heat exchange system, and the refrigerant in the fluid reservoir can enter the heat exchange cycle, or the refrigerant in the heat exchange cycle can enter the fluid reservoir, or keep the refrigerant amount in the fluid reservoir unchanged. Therefore, the on-demand access of the refrigerant to the heat exchange cycle is realized, and the refrigerant amount for the heat exchange cycle is always kept in an appropriate state, to reduce the power of the heat exchange system and improving the energy efficiency of the heat exchange system. 
       FIG.  4    shows a flow chart of a control method for air conditioning apparatus provided by some embodiments of the present disclosure. 
     As shown in  FIG.  4   , the specific process of the control method for air conditioning apparatus provided by an embodiment of the present disclosure is as follows: 
     Step  402 : acquiring, in the case of operating heating mode, the refrigerant amount for heat exchange cycle in the heat exchange system; 
     Step  404 : in the case that the refrigerant amount is less than a first refrigerant amount threshold, opening the first valve body and closing the second valve body; 
     Step  406 : in the case that the refrigerant amount is greater than or equal to the first refrigerant amount threshold and less than a second refrigerant amount threshold, closing the first valve body and the second valve body; 
     Step  408 : in the case that the refrigerant amount is greater than or equal to the second refrigerant amount threshold, closing the first valve body and opening the second valve body. 
     The control method for air conditioning apparatus provided by embodiments of the present disclosure, by setting the first refrigerant amount threshold and the second refrigerant amount threshold, the first refrigerant amount threshold is less than the second refrigerant amount threshold. If the refrigerant amount for the heat exchange cycle in the heat exchange system is less than the first refrigerant amount threshold, it means that the refrigerant amount for the heat exchange cycle in the heat exchange system is insufficient. At this time, the first valve body is opened, and the second valve body is closed, and the refrigerant in the fluid reservoir enters the compressor under the influence of the compressor suction port, to increase the refrigerant amount for heat exchange in the heat exchange system. 
     If the refrigerant amount for heat exchange cycle in the heat exchange system is greater than or equal to the first refrigerant amount threshold and less than the second refrigerant amount threshold. It means that the refrigerant amount for heat exchange cycle in the heat exchange system is appropriate. At this time, the first valve body and the second valve body are closed, and the refrigerant for heat exchange cycle in the heat exchange system remains unchanged. 
     If the refrigerant amount for heat exchange cycle in the heat exchange system is greater than or equal to the second refrigerant amount threshold. It means that the refrigerant amount for heat exchange cycle in the heat exchange system is excessive. At this time, when the first valve body is closed and the second valve body is opened, the refrigerant for heat exchange cycle in the heat exchange system can enter the fluid reservoir, to reduce the refrigerant amount for heat exchange in the heat exchange system. 
     As mentioned above, the refrigerant amount for heat exchange cycle in the heat exchange system is dynamically controlled, and the refrigerant amount for heat exchange cycle in the heat exchange system is always in an appropriate state. Therefore, the power of the heat exchange system is reduced, and the energy efficiency of the heat exchange system is improved. 
     It should be noted that the first refrigerant amount threshold and the second refrigerant amount threshold can be set according to actual conditions such as the power of the compressor, the total refrigerant amount in the heat exchange system, and the heat exchange efficiency of the heat exchanger. 
     In some embodiments, in the case of operating the cooling mode, opening the first valve body and closing the second valve body. 
     In this embodiment, when the air conditioning apparatus operates in cooling mode, the first valve body is opened and the second valve body is closed. Therefore, the refrigerant in the fluid reservoir enters the compressor and enters the heat exchange cycle of the heat exchange system, to meet the cooling demand of the air conditioning apparatus, to reduce the power and improving the energy efficiency. 
     The connection in the present disclosure comprises connecting via pipeline; the communication comprises communicating via pipeline. 
       FIG.  5    shows a partial flow chart of a control method for air conditioning apparatus provided by some embodiments of the present disclosure. 
     As shown in  FIG.  5   , a part of the specific process of the control method for air conditioning apparatus provided by the embodiment of the present disclosure is as follows: 
     Step  502 : in the case of operating heating mode, checking operating state of the compressor; 
     Step  504 : when the compressor is stopped, closing the first valve body and opening the second valve body. 
     In some embodiments, the present disclosure provides a control method for air conditioning apparatus, based on the air conditioning apparatus provided in any one of the above-mentioned embodiments, that is, when the four-way valve works according to the hollow arrow, when the air conditioning apparatus operates in heating mode, the refrigerant circulation path is, compressor→four-way valve→second heat exchanger→throttle device→first heat exchanger→four-way valve→compressor; When the four-way valve works according to the solid arrow, when the air conditioning apparatus operates in cooling mode, the refrigerant circulation path is, compressor→four-way valve→first heat exchanger→throttle device→second heat exchanger→four-way valve→compressor. 
     Furthermore, the recovery of the refrigerant on the side of second heat exchanger is realized by using the fluid reservoir, the first valve body and the second valve body. Moreover, after the air conditioning apparatus is operating under heating conditions and stopped, a large amount of high-pressure refrigerant will remain on the side of second heat exchanger, and the refrigerant on the side of second heat exchanger is in a high-pressure state. At this time, by opening the second valve body and closing the first valve body, the refrigerant on the side of second heat exchanger can be discharged into the fluid reservoir, to realize the recovery of the high-pressure refrigerant on the side of second heat exchanger. Since the refrigerant amount on the side of second heat exchanger is reduced, the following problems are avoided: that is, due to a large amount of refrigerant remaining on the side of second heat exchanger, the refrigerant is cooled on the side of second heat exchanger, to cause the freezing tube of the second heat exchanger. This provides antifreeze protection for the second heat exchanger and improves the performance of the heat exchange system. And after the heat exchange system is restarted, the first heat exchanger can be turned on, and the second heat exchanger can be turned off, because the pressure at the suction port of the compressor is low, the refrigerant stored in the fluid reservoir can be re-inhaled into the compressor, and the refrigerant circulation can be continued to ensure the refrigerant amount for heat exchange cycle in the heat exchange system. 
     For example, in the heating mode, the refrigerant is in a high-pressure state on the side of second heat exchanger. At this time, the pressure at the connection between one side of the second valve body and the second heat exchanger is greater than the pressure in the fluid reservoir. Then, after opening the second valve body, the refrigerant will flow into the fluid reservoir under the action of pressure, and the purpose of discharging the refrigerant in the second heat exchanger. Thereby avoiding the accumulation of refrigerant in the second heat exchanger after shutdown, and causing the cooling of the side of second heat exchanger after evaporating and absorbing heat, avoiding the risk of freezing tubes. 
       FIG.  6    shows a partial flow chart of a control method for air conditioning apparatus provided by embodiments of the present disclosure. 
     As shown in  FIG.  6   , a part of the specific process of the control method for air conditioning apparatus provided by the embodiment of the present disclosure is as follows: 
     Step  602 : in the case of operating heating mode, checking operating state of the compressor; 
     Step  604 : when the compressor is stopped, closing the first valve body and opening the second valve body. 
     The present disclosure provides a control method for air conditioning apparatus, on the basis of some embodiments, furthermore, when the throttle device comprises an electronic expansion valve, after the air conditioning apparatus operates in heating mode and stops, closing the first valve body and the electronic expansion valve, open the second valve body. Therefore, the high-pressure refrigerant can be intercepted on the side of second heat exchanger to improve the recovery effect of the fluid reservoir on the refrigerant and the effect of antifreeze protection on the second heat exchanger. 
     In some embodiments, based on the condition of operating the hot and cold mode, the operating state of the compressor is detected; when the compressor stops operating, the first valve body and the second valve body are closed. 
     In this embodiment, when the air conditioning apparatus operates in cooling mode, when the compressor is stopped, the first valve body and the second valve body are closed, and there is a sufficient circulating refrigerant amount when it is convenient to turn on the air conditioning apparatus again after the cooling mode. 
     The connection in the present disclosure comprises connecting via pipeline; the communication comprises communicating via pipeline. 
     In the present disclosure, the terms “installing”, “connected”, “connection”, “fixing” and the like should be understood in a broad sense. For example, “connection” may be a fixed connection, a removable connection or an integral connection; and “connected” may refer to direct connection or indirect connection through an intermediary. Understanding of the specific meaning of the terms in the present disclosure according to specific situations. 
     In the description of the present specification, the descriptions of the terms “one embodiment”, “some embodiments” and “exemplary embodiments” and the like mean that specific features, structures, materials or characteristics described in conjunction with the embodiment(s) or example(s) are comprised in at least one embodiment or example of the present disclosure. In the specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an adapted manner in any one or more embodiments or examples.