Single-stage and cascade cycle free conversion heat pump system

Abstract

The present invention provides a heat pump system with single-stage and cascade cycle free conversion, including a first single-stage circulation system, a second single-stage circulation system and an intermediate heat exchanger system, the first single-stage circulation system includes a first outdoor unit module and at least one first indoor unit module; the second single-stage circulation system includes a second outdoor unit module and at least one second indoor unit module; the intermediate heat exchanger system is connected to the first single-stage circulation system and the second single-stage circulation system respectively; the first single-stage circulation system, the second single-stage circulation system and the intermediate heat exchanger system are combined into a cascade circulation system, and in the cascade circulation system, the first single-stage circulation system or the second single-stage circulation system can be used as a high-temperature stage. In the present invention, the system can efficiently meet the heat requirements of different temperature grades.

Description

Technical Field

[0001] The invention relates to the technical field of refrigeration heat pumps, and in particular to a single-stage, cascade cycle free-conversion heat pump system. Background Art

[0002] As an important heating and cooling equipment, heat pump has the advantages of high efficiency, energy saving, safety and reliability. It plays an important role in heating civil buildings, domestic hot water, and the production of hot air and hot water in industrial processes. For heat pump systems with large temperature differences between the heat source side and the user side, such as low-temperature heat pump systems operating in low-temperature environments, or industrial heat pumps that need to produce high-temperature hot air and hot water, the use of ordinary single-stage compression cycle systems is often difficult to adapt to large pressure ratios, which leads to the attenuation of heating capacity and reduced energy efficiency; while the use of multi-stage compression systems will be limited by aspects such as the performance of the refrigerant itself and the pressure bearing capacity of the unit. Therefore, for such low-temperature heat pumps and industrial heat pumps that need to adapt to large pressure ratios, the use of cascade cycles will effectively improve the performance of heat pump products. The cascade cycle can divide the large total temperature difference into two or several sections, select the appropriate refrigerant cycle according to the temperature zone of each section, and then superimpose them, which can reduce the pressure ratio at both ends of the heat source side and the user side and improve the operating performance of each section.

[0003] Taking industrial high-temperature heat pumps as an example, since industrial loads often change, different products have different requirements for process temperatures, and the use of single-stage compression systems and cascade systems alone cannot meet the temperature change requirements at the same time. In addition, for cold and extremely cold areas in northern my country, low-temperature air source heat pumps used to produce normal temperature hot water and wind also need to face the needs of different terminal temperatures, such as different needs for heating and domestic hot water, and changes in the temperature of the outdoor heat source side. Single-stage compression systems and cascade systems alone cannot meet the above changes at the same time. The multi-connected heat pump system only requires one host and can deliver refrigerant to multiple terminals to meet the needs of multiple user-side terminals. It also has the advantages of energy saving, intelligent regulation and control of different terminals.

[0004] In order to meet different temperature requirements, adapt to a large pressure ratio range, and meet the differences of different terminals, such as the low temperature, small temperature difference, and low pressure ratio of the heat pump heating terminal in winter; while the hot water temperature is high when producing domestic hot water, it is necessary to meet the heating requirements of a large pressure ratio, and the required temperature for different users and terminals is different. Therefore, it is urgent to develop an efficient variable temperature multi-connected heat pump system that meets the large temperature difference between the heat source side and the user side and can adapt to the pressure ratio requirements of different user sides. Summary of the invention

[0005] The embodiment of the present invention provides a single-stage, cascade cycle freely convertible heat pump system, which is used to solve the problem that the heat pump system in the prior art cannot adapt to the end of different heating temperatures.

[0006] The embodiment of the present invention provides a single-stage, cascade cycle free-conversion heat pump system, comprising:

[0007] A first single-stage circulation system includes a first outdoor unit module and at least one first indoor unit module;

[0008] A second single-stage circulation system includes a second outdoor unit module and at least one second indoor unit module;

[0009] The intermediate heat exchanger system is connected to the first single-stage circulation system and the second single-stage circulation system respectively; wherein,

[0010] The first single-stage circulation system and the second single-stage circulation system can operate independently or be combined with the intermediate heat exchanger system to form a cascade circulation system. In the cascade circulation system, the first single-stage circulation system or the second single-stage circulation system can serve as the high-temperature stage.

[0011] According to a single-stage, cascade cycle free conversion heat pump system of one embodiment of the present invention,

[0012] The intermediate heat exchanger system comprises an evaporative condenser, and a first tube body, a second tube body, a third tube body and a fourth tube body connected to the evaporative condenser;

[0013] The first outdoor unit module and the first indoor unit module have opposite sides connected to the first pipe body and the third pipe body;

[0014] The second outdoor unit module and the second indoor unit module have opposite sides connected to the second pipe body and the fourth pipe body.

[0015] According to a single-stage, cascade cycle free conversion heat pump system of one embodiment of the present invention,

[0016] The first indoor unit module includes a first indoor heat exchanger and a first throttling device connected to the first indoor heat exchanger and in communication with the third pipe body;

[0017] The second indoor unit module includes a second indoor heat exchanger and a second throttling device connected to the second indoor heat exchanger and communicated with the fourth pipe body.

[0018] According to a single-stage, cascade cycle free conversion heat pump system of one embodiment of the present invention,

[0019] The first outdoor unit module includes a third throttling device, a first outdoor heat exchanger connected to the third throttling device, a first four-way reversing valve, a first compressor, and a first gas-liquid separation device connected to the first compressor;

[0020] The second outdoor unit module includes a fourth throttling device, a second outdoor heat exchanger connected to the fourth throttling device, a second four-way reversing valve, a second compressor, and a second gas-liquid separation device connected to the second compressor box.

[0021] According to a single-stage, cascade cycle free conversion heat pump system of one embodiment of the present invention,

[0022] The first tube body includes a first flow tube, a second flow tube, a third flow tube and a fourth flow tube;

[0023] The gas in the first flow pipe flows from the first indoor unit module to the intermediate heat exchanger system; the second flow pipe is connected to the first flow pipe and flows through the first four-way reversing valve and the first gas-liquid separation device; the third flow pipe is connected to the second flow pipe and flows to the first outdoor heat exchanger and the third throttling device; the fourth flow pipe is connected to the second flow pipe and the third flow pipe and flows to the intermediate heat exchanger system;

[0024] The second tube body includes a fifth flow tube, a sixth flow tube, a seventh flow tube and an eighth flow tube;

[0025] The gas in the fifth flow pipe flows from the second indoor unit module to the intermediate heat exchanger system, the sixth flow pipe is connected to the fifth flow pipe and flows through the second four-way reversing valve and the second gas-liquid separation device; the seventh flow pipe is connected to the sixth flow pipe and flows to the second outdoor heat exchanger and the fourth throttling device; the eighth flow pipe is connected to the sixth flow pipe and the seventh flow pipe and flows to the intermediate heat exchanger system.

[0026] According to a single-stage, cascade cycle free conversion heat pump system of one embodiment of the present invention,

[0027] The intermediate heat exchanger system further includes a fifth throttling device, a sixth throttling device, a third four-way reversing valve and a fourth four-way reversing valve;

[0028] The fifth throttling device is arranged on the third pipe body, and the third four-way reversing valve is connected to the first flow pipe and the fourth flow pipe respectively;

[0029] The sixth throttling device is arranged on the fourth pipe body, and the fourth four-way reversing valve is connected to the fifth flow pipe and the eighth flow pipe respectively.

[0030] According to a single-stage, cascade cycle free conversion heat pump system of one embodiment of the present invention,

[0031] The first single-stage circulation system further includes a first defrost passage, the first defrost passage being connected to the second flow pipe and the outlet side of the first outdoor heat exchanger respectively;

[0032] The second single-stage circulation system further includes a second defrost passage, which is respectively connected to the sixth flow pipe and an outlet side of the second outdoor heat exchanger.

[0033] According to a heat pump system with free conversion between single-stage and cascade cycles according to one embodiment of the present invention, in the cascade cycle system, the first single-stage cycle system or the second single-stage cycle system can be the high-temperature side or the low-temperature side.

[0034] According to a single-stage and cascade cycle free conversion heat pump system according to one embodiment of the present invention, in the cascade cycle system, the high-temperature stage side is used to maintain a condensing temperature higher than that maintained when the first single-stage cycle system or the second single-stage cycle system operates alone.

[0035] According to a single-stage and cascade cycle free conversion heat pump system according to one embodiment of the present invention, in the cascade cycle system, the evaporative condenser includes an evaporation side and a condensation side; the evaporation side or the condensation side corresponds to the evaporation end and the condensation end in the first single-stage cycle system or the second single-stage cycle system respectively.

[0036] The heat pump system with free conversion between single-stage and cascade cycles provided by the present invention comprises a first single-stage circulation system, a second single-stage circulation system and an intermediate heat exchanger system, and thus the first single-stage circulation system and the second single-stage circulation system can both work independently for cooling or heating, and when the first single-stage circulation system, the second single-stage circulation system and the intermediate heat exchanger system together form a cascade circulation system, the first single-stage circulation system or the second single-stage circulation system can both serve as the high-temperature side, thereby being able to adapt to heat requirements of different temperature grades. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 It is a structural schematic diagram of an embodiment of a heat pump system with single-stage and cascade cycle free conversion according to the present invention;

[0039] Figure 2 It is a structural schematic diagram of another embodiment of the heat pump system with single-stage and cascade cycle free conversion according to the present invention;

[0040] Figure 3It is a structural schematic diagram of a third embodiment of a heat pump system with single-stage and cascade cycle free conversion according to the present invention;

[0041] Reference numerals:

[0042] 10: first single-stage circulation system; 110: first outdoor unit module; 1110: third throttling device; 1120: first outdoor heat exchanger; 1130: first four-way reversing valve; 1140: first compressor; 1150: first gas-liquid separation device

[0043] 120: first indoor unit module; 1210: first indoor heat exchanger; 1220: first throttling device; 130: first defrosting channel; 20: second single-stage circulation system; 210: second outdoor unit module; 2110: fourth throttling device; 2120: second outdoor heat exchanger;

[0044] 2150: second gas-liquid separation device; 2130: second four-way reversing valve; 2140: second compressor;

[0045] 220: second indoor unit module; 2210: second indoor heat exchanger; 2220: second throttling device; 230: second defrosting channel; 30: intermediate heat exchanger system; 310: evaporative condenser;

[0046] 3110: evaporation side; 3120: condensation side; 320: first tube body;

[0047] 3210: first flow tube; 3220: second flow tube; 3230: third flow tube;

[0048] 3240: fourth flow tube; 330: second tube body; 3310: fifth flow tube;

[0049] 3320: sixth flow tube; 3330: seventh flow tube; 3340: eighth flow tube;

[0050] 340: the third tube body; 350: the fourth tube body; 360: the fifth throttling device;

[0051] 370: sixth throttling device; 380: third four-way reversing valve; 390: fourth four-way reversing valve; 40: defrost valve. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Combine the following Figure 1 and Figure 3 The present invention provides a heat pump system with free conversion between single-stage and cascade cycles, comprising a first single-stage circulation system 10, a second single-stage circulation system 20 and an intermediate heat exchanger system 30, wherein the first single-stage circulation system 10 comprises a first outdoor unit module 110 and at least one first indoor unit module 120; the second single-stage circulation system 20 comprises a second outdoor unit module 210 and at least one second indoor unit module 220; the intermediate heat exchanger system 30 is respectively connected to the first single-stage circulation system 10 and the second single-stage circulation system 20; wherein the first single-stage circulation system 10 and the second single-stage circulation system 20 can be operated independently or combined with the intermediate heat exchanger system 30 to form a cascade circulation system, and in the cascade circulation system, the first single-stage circulation system 10 or the second single-stage circulation system 20 can be used as the high-temperature stage side. That is, when the first single-stage circulation system 10 or the second single-stage circulation system 20 is operating alone, the temperature of the room temperature maintained by the first indoor unit module 120 or the second indoor unit module 220 is lower than the temperature of the room temperature maintained by the first indoor unit module 120 or the second indoor unit module 220 in the cascade circulation system. It should be noted that when the first single-stage circulation system 10 or the second single-stage circulation system 20 is working alone, the first single-stage circulation system 10 or the second single-stage circulation system 20 can be heated or cooled respectively. When the first single-stage circulation system 10, the second single-stage circulation system 20 and the intermediate heat exchanger system 30 are combined into a cascade circulation system, the first single-stage circulation system 10 or the second single-stage circulation system 20 can be a high-temperature stage. Taking the first single-stage circulation system 10 as an example of a high-temperature stage, the temperature of the room temperature maintained by the first indoor unit module 120 of the first single-stage circulation system 10 is higher than the temperature of the room temperature maintained when the first single-stage circulation system 10 is working alone. Therefore, when the cascade circulation system is running, the system can provide high-temperature hot water to users to meet different grades of heat needs. Specifically, Figure 1 It is a structural schematic diagram of an embodiment of a heat pump system with single-stage and cascade cycle free conversion according to the present invention; Figure 2 It is a structural schematic diagram of another embodiment of the heat pump system with single-stage and cascade cycle free conversion according to the present invention; Figure 3 This is a schematic diagram of the structure of the third embodiment of the heat pump system with single-stage and cascade cycle free conversion according to the present invention. It should be noted that: Figure 2 and Figure 3 All in Figure 1 Based on the improvements made Figure 2 Zhongzai Figure 1 On the basis of adding a defrost channel, Figure 3 exist Figure 1 On the basis of the invention, a plurality of four-way reversing valves are added, so that the first single-stage circulation system 10 and the second single-stage circulation system 20 can be combined into a cascade circulation system to further meet the heat requirements of different grades.

[0054] The intermediate heat exchanger system includes an evaporative condenser 310, and a first tube body 320, a second tube body 330, a third tube body 340 and a fourth tube body 350 connected to the evaporative condenser 310; the first outdoor unit module 110 and the first indoor unit module 120 are connected to the first tube body 320 and the third tube body 340 on opposite sides; the second outdoor unit module 210 and the second indoor unit module 220 are connected to the second tube body 330 and the fourth tube body 350 on opposite sides.

[0055] For the first single-stage circulation system 10, the first indoor unit module 120 includes a first indoor heat exchanger 1210 and a first throttling device 1220 connected to the first indoor heat exchanger 1210 and connected to the third pipe body 340. The first outdoor unit module 110 includes a third throttling device 1110, a first outdoor heat exchanger 1120 connected to the third throttling device 1110, a first four-way reversing valve 1130, a first compressor 1140, and a first gas-liquid separation device 1150 connected to the first compressor 1140. The first pipe body 320 includes a first flow pipe 3210, a second flow pipe 3220, a third flow pipe 3230, and a fourth flow pipe 3240. The gas in the first circulation pipe 3210 flows from the first indoor unit module 120 to the intermediate heat exchanger system 30, the second circulation pipe 3220 is connected to the first circulation pipe 3210 and flows through the first four-way reversing valve 1130 and the first gas-liquid separation device 1150; the third circulation pipe 3230 is connected to the second circulation pipe 3220 and flows to the first outdoor heat exchanger 1120 and the third throttling device 1110; the fourth circulation pipe 3240 is connected to the second circulation pipe 3220 and the third circulation pipe 3230 and flows to the intermediate heat exchanger system 30.

[0056] For the second single-stage circulation system 20, the second indoor unit module 220 includes a second indoor heat exchanger 2210 and a second throttling device 2220 connected to the second indoor heat exchanger 2210 and in communication with the fourth pipe body 350. The second outdoor unit module 210 includes a fourth throttling device 2110, a second outdoor heat exchanger 2120 connected to the fourth throttling device 2110, a second four-way reversing valve 2130, a second compressor 2140, and a second gas-liquid separation device 2150 connected to the second compressor 2140 box. The second pipe body 330 includes a fifth flow pipe 3310, a sixth flow pipe 3320, a seventh flow pipe 3330 and an eighth flow pipe 3340; the gas in the fifth flow pipe 3310 flows from the second indoor unit module 220 to the intermediate heat exchanger system 30, the sixth flow pipe 3320 is connected to the fifth flow pipe 3310 and flows through the second four-way reversing valve 2130 and the second gas-liquid separation device 2150; the seventh flow pipe 3330 is connected to the sixth flow pipe 3320 and flows to the second outdoor heat exchanger 2120 and the fourth throttling device 2110; the eighth flow pipe 3340 is connected to the sixth flow pipe 3320 and the seventh flow pipe 3330 and flows to the intermediate heat exchanger system 30.

[0057] Furthermore, the intermediate heat exchanger system 30 also includes a fifth throttling device 360, a sixth throttling device 370, a third four-way reversing valve 380 and a fourth four-way reversing valve 390; the fifth throttling device 360 ​​is arranged on the third pipe body 340, and the third four-way reversing valve 380 is respectively connected to the first flow pipe 3210 and the fourth flow pipe 3240; the sixth throttling device 370 is arranged on the fourth pipe body 350, and the fourth four-way reversing valve 390 is respectively connected to the fifth flow pipe 3310 and the eighth flow pipe 3340.

[0058] In addition, the first single-stage circulation system 10 also includes a first defrost channel 130, which is respectively connected to the second circulation pipe 3220 and the outlet side of the first outdoor heat exchanger 1120; the second single-stage circulation system 20 also includes a second defrost channel 230, which is respectively connected to the sixth circulation pipe 3320 and the outlet side of the second outdoor heat exchanger 2120.

[0059] The first four-way reversing valve 1130S side is connected to the inlet of the first gas-liquid separation device 1150, the first four-way reversing valve 1130D side is connected to the outlet of the first compressor 1140, the first four-way reversing valve 1130C side is connected to the inlet side of the first outdoor heat exchanger 1120, and the first four-way reversing valve 1130E side is connected to the inlet of the first indoor unit module 120. The second four-way reversing valve 2130S side is connected to the inlet of the second gas-liquid separation device 2150, the second four-way reversing valve 2130D side is connected to the outlet of the second compressor 2140, the second four-way reversing valve 2130E side is connected to the inlet of the second indoor unit module 220, and the second four-way reversing valve 2130C side is connected to the inlet side of the second outdoor heat exchanger 2120. The third four-way reversing valve 380S side is connected to the outlet side of the first compressor 1140, the third four-way reversing valve 380C side is closed, the third four-way reversing valve 380E side is connected to the evaporative condenser 310, and the third four-way reversing valve 380D side is connected to the first indoor unit module 120. The fourth four-way reversing valve 390S side is connected to the outlet side of the second compressor 2140, the fourth four-way reversing valve 390C side is closed, the fourth four-way reversing valve 390E side is connected to the evaporative condenser 310, and the fourth four-way reversing valve 390D side is connected to the second indoor unit module 220.

[0060] In one embodiment of the present invention, the first single-stage circulation system 10 or the second single-stage circulation system 20 can both be used for refrigeration. Here, the first single-stage circulation system 10 is taken as an example: Please continue to refer to Figure 1 , the first four-way reversing valve 1130E side is connected to the first four-way reversing valve 1130S side, the first four-way reversing valve 1130D side is connected to the first four-way reversing valve 1130C side, and the third throttling device 1110 is opened. In the intermediate heat exchanger system 30, the third four-way reversing valve 380S side is connected to the third four-way reversing valve 380C side, the third four-way reversing valve 380E side is connected to the third four-way reversing valve 380D side, the fourth four-way reversing valve 390S side is connected to the fourth four-way reversing valve 390C side, and the fourth four-way reversing valve 390E side is connected to the fourth four-way reversing valve 390D side. The evaporative condenser 310 is closed. In the first single-stage cycle system 10, the refrigerator completes a single-stage compression cycle through the first compressor 1140, the first four-way reversing valve 1130, the first outdoor heat exchanger 1120, the third throttling device 1110, the first throttling device 1220, the first indoor heat exchanger 1210 and the first gas-liquid separation device 1150. The first indoor unit module 120 of the first single-stage cycle system 10 acts as an evaporator to provide cooling capacity to the room for cooling.

[0061] The first single-stage circulation system 10 or the second single-stage circulation system 20 can also generate heat. Here, the first single-stage circulation system 10 is taken as an example: the first four-way reversing valve 1130D side is connected to the first four-way reversing valve 1130E side, and the first four-way reversing valve 1130S side is connected to the first four-way reversing valve 1130C side. The third throttling device 1110 is opened. In the intermediate heat exchanger system 30, the third four-way reversing valve 380D side is connected to the third four-way reversing valve 380C side, and the third four-way reversing valve 380E side is connected to the third four-way reversing valve 380S side; the fourth four-way reversing valve 390D side is connected to the fourth four-way reversing valve 390C side, and the fourth four-way reversing valve 390E side is connected to the fourth four-way reversing valve 390S side. The fifth throttling device 360 ​​and the sixth throttling device 370 are closed, and the evaporative condenser 310 is closed. For the first single-stage circulation system 10, the refrigerator sequentially passes through the first compressor 1140, the first four-way reversing valve 1130, the first indoor heat exchanger 1210, the first throttling device 1220, the third throttling device 1110, the first outdoor heat exchanger 1120, the first four-way reversing valve 1130 and the first gas-liquid separation device 1150 to complete a single-stage compression cycle. The first indoor unit module 120 of the first single-stage circulation system 10 acts as a condenser to provide heating to the room for heating.

[0062] When the cascade circulation system is in operation, the first single-stage circulation system 10 and the second single-stage circulation system 20 can both be used as a low-temperature stage or a high-temperature stage. Figure 1, taking the first single-stage circulation system 10 as a high-temperature stage as an example: the first four-way reversing valve 1130D side is connected to the first four-way reversing valve 1130E side, the first four-way reversing valve 1130C side is connected to the first four-way reversing valve 1130S side, and the third throttling device 1110 is closed. In the intermediate heat exchanger system 30, the third four-way reversing valve 380D side is connected to the third four-way reversing valve 380C side, the third four-way reversing valve 380E side is connected to the third four-way reversing valve 380S side, the fourth four-way reversing valve 390D side is connected to the fourth four-way reversing valve 390E side, the fourth four-way reversing valve 390C side is connected to the fourth four-way reversing valve 390S side, the fifth throttling device 360 ​​and the sixth throttling device 370. In the second single-stage circulation system 20, the second four-way reversing valve 2130E side is connected to the second four-way reversing valve 2130D side, and the second four-way reversing valve 2130C side is connected to the second four-way reversing valve 2130S side. The fourth throttling device 2110 is opened, and the second indoor unit module 220 is completely closed. For the high-temperature stage operation of the first single-stage circulation system 10, the first indoor unit module 120 releases heat to the environment, and the evaporative condenser 310 serves as the evaporator of the first single-stage circulation system 10. The second single-stage circulation system 20 is a low-temperature machine operation, the evaporative condenser 310 serves as the condenser of the second single-stage circulation system 20, and the second outdoor heat exchanger 2120 serves as the evaporator of the second single-stage circulation system 20. In the cascade circulation system, the evaporative condenser 310 includes an evaporation side 3110 and a condensation side 3120, that is, the specific details can be referred to. Figure 3 , when the first single-stage circulation system 10 is at the low temperature side, the side of the evaporative condenser 310 close to the first single-stage circulation system 10 is the condensation side 3120, which also corresponds to the evaporative condenser 310 being a condenser in the first single-stage circulation system 10 and being an evaporator in the second single-stage circulation system 20. Therefore, the side of the evaporative condenser 310 close to the second single-stage circulation system 20 is the evaporation side 3110. It should be noted that, by the same token, when the second single-stage circulation system 20 is at the low temperature side, the evaporation side 3110 and the condensation side 3120 are arranged in the opposite positions to those when the first single-stage circulation system 10 is at the low temperature side, which will not be described in detail here.

[0063] For further information, please refer to Figure 2 and Figure 3The present invention also provides a hot gas bypass defrosting mode. When the first outdoor heat exchanger 1120 in the first single-stage circulation system 10 or the second outdoor heat exchanger 2120 in the second single-stage circulation system 20 is frosted, the hot gas bypass defrosting mode can be used for defrosting. Taking the first single-stage circulation system 10 as an example, when the first outdoor heat exchanger 1120 is frosted, the defrost valve 40 and the third throttling device 1110 are opened, and the high-temperature exhaust gas enters the first outdoor heat exchanger 1120 from the first compressor 1140 through the defrost valve 40 and the defrost pipe for defrosting, and then returns to the first compressor 1140 through the first gas-liquid separation device 1150.

[0064] In another embodiment, the first indoor heat exchanger 1210 and the second indoor heat exchanger 2210 are refrigerant-water heat exchangers, and the water side is connected to the heat user through a water distributor, a water collector and a water pump to deliver high-temperature hot water to the heat user.

[0065] In summary, when the first single-stage circulation system 10 and the second single-stage circulation system 20 are operated separately, they can provide cold water or low-temperature hot water to users. That is, in the cascade circulation system, the high-temperature stage side is used to maintain a condensation temperature higher than that maintained when the first single-stage circulation system 10 or the second single-stage circulation system 20 is operated separately. Therefore, in the cascade circulation system, the system can provide hot water with a higher temperature to heat users than that generated when the first single-stage circulation system 10 or the second single-stage circulation system 20 is operated separately, and the first single-stage circulation system 10 or the second single-stage circulation system 20 can be operated separately, and multiple systems can be converted to meet different grades of heat needs.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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 make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A single-stage, cascade cycle free conversion heat pump system, characterized in that: include: A first single-stage circulation system includes a first outdoor unit module and at least one first indoor unit module; A second single-stage circulation system includes a second outdoor unit module and at least one second indoor unit module; The intermediate heat exchanger system is connected to the first single-stage circulation system and the second single-stage circulation system respectively; wherein, The first single-stage circulation system and the second single-stage circulation system can be operated independently or combined with the intermediate heat exchanger system to form a cascade circulation system, and in the cascade circulation system, the first single-stage circulation system or the second single-stage circulation system can serve as a high-temperature stage; The intermediate heat exchanger system includes an evaporative condenser, and a first tube body, a second tube body, a third tube body, and a fourth tube body connected to the evaporative condenser; opposite sides of the first outdoor unit module and the first indoor unit module are connected to the first tube body and the third tube body; opposite sides of the second outdoor unit module and the second indoor unit module are connected to the second tube body and the fourth tube body; The first indoor unit module includes a first indoor heat exchanger and a first throttling device connected to the first indoor heat exchanger and communicated with the third pipe body; the second indoor unit module includes a second indoor heat exchanger and a second throttling device connected to the second indoor heat exchanger and communicated with the fourth pipe body; In the cascade cycle system, the high temperature stage is used to maintain a condensing temperature higher than that maintained when the first single-stage cycle system or the second single-stage cycle system is operated alone; The first outdoor unit module includes a third throttling device, a first outdoor heat exchanger connected to the third throttling device, a first four-way reversing valve, a first compressor, and a first gas-liquid separation device connected to the first compressor; The second outdoor unit module includes a fourth throttling device, a second outdoor heat exchanger connected to the fourth throttling device, a second four-way reversing valve, a second compressor, and a second gas-liquid separation device connected to the second compressor box; The first tube body includes a first flow tube, a second flow tube, a third flow tube and a fourth flow tube; The gas in the first flow pipe flows from the first indoor unit module to the intermediate heat exchanger system; the second flow pipe is connected to the first flow pipe and flows through the first four-way reversing valve and the first gas-liquid separation device; the third flow pipe is connected to the second flow pipe and flows to the first outdoor heat exchanger and the third throttling device; the fourth flow pipe is connected to the second flow pipe and the third flow pipe and flows to the intermediate heat exchanger system; The second tube body includes a fifth flow tube, a sixth flow tube, a seventh flow tube and an eighth flow tube; The gas of the fifth flow pipe flows from the second indoor unit module to the intermediate heat exchanger system, the sixth flow pipe is connected to the fifth flow pipe and flows through the second four-way reversing valve and the second gas-liquid separation device; the seventh flow pipe is connected to the sixth flow pipe and flows to the second outdoor heat exchanger and the fourth throttling device; the eighth flow pipe is connected to the sixth flow pipe and the seventh flow pipe and flows to the intermediate heat exchanger system; The intermediate heat exchanger system further includes a fifth throttling device, a sixth throttling device, a third four-way reversing valve and a fourth four-way reversing valve; The fifth throttling device is arranged on the third pipe body, and the third four-way reversing valve is connected to the first flow pipe and the fourth flow pipe respectively; The sixth throttling device is arranged on the fourth pipe body, and the fourth four-way reversing valve is connected to the fifth flow pipe and the eighth flow pipe respectively.

2. The single-stage, cascade cycle free conversion heat pump system according to claim 1 is characterized in that: The first single-stage circulation system further includes a first defrost passage, the first defrost passage being connected to the second flow pipe and the outlet side of the first outdoor heat exchanger respectively; The second single-stage circulation system further includes a second defrost passage, which is respectively connected to the sixth flow pipe and an outlet side of the second outdoor heat exchanger.

3. The single-stage, cascade cycle free conversion heat pump system according to claim 2 is characterized in that: In the cascade circulation system, the first single-stage circulation system or the second single-stage circulation system can be a high-temperature side or a low-temperature side.

4. The single-stage, cascade cycle free conversion heat pump system according to claim 1 is characterized in that: In the cascade circulation system, the evaporative condenser includes an evaporation side and a condensation side; the evaporation side or the condensation side corresponds to the evaporation end and the condensation end in the first single-stage circulation system or the second single-stage circulation system, respectively.

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