Air source heat pump system and control method thereof

Abstract

The invention relates to the technical field of air source heat pumps, and discloses an air source heat pump system and a control method thereof.The air source heat pump system is suitable for application of a single low-temperature-stage refrigerant and comprises a compressor, a first heat exchanger, a second heat exchanger, a mixing pipe set and heat dissipation equipment; a refrigerant circularly flows among the compressor, the first heat exchanger and the second heat exchanger to form a gas circulation loop, heat exchange fluid circularly flows in the second heat exchanger, the mixing pipe set and the heat dissipation equipment to form a liquid circulation loop, heat exchange of the gas circulation loop and the liquid circulation loop is cut off in the second heat exchanger, and the mixing pipe set is provided with a temperature return pipe. The temperature return pipe and the second heat exchanger are arranged in parallel, various supply and return water temperature differences are achieved, and therefore the requirements in various temperature environments are met, and the air source heat pump system can achieve application of a single low-temperature-stage refrigerant, simplify the system structure, reduce the failure rate and improve the stability.

Description

Technical Field

[0001] The present invention relates to the technical field of air source heat pumps, and in particular to an air source heat pump system and a control method thereof. Background Art

[0002] Carbon dioxide (CO) is a recognized environmentally friendly refrigerant with many excellent properties and characteristics. Its global warming potential (GWP) is 1, its ozone depletion potential (ODP) is 0, it does not require artificial synthesis, and it has excellent physical properties, making it one of the ideal choices in future refrigerant replacement plans. Especially in low temperature environments (such as -30°C), heat pump systems using CO as refrigerant can still provide high-temperature hot water over 90°C, which is enough to meet various civil and industrial heating needs.

[0003] However, CO has a low critical temperature (31°C), and can only effectively exert its unique advantages under transcritical large temperature difference circulation conditions. This characteristic has led to the current CO air source heat pump being mainly used in the field of large temperature difference direct heating hot water, while in small temperature difference heating applications such as heating and circulating hot water, its energy saving effect is poor.

[0004] To overcome this limitation, the industry often uses low-temperature CO and high-temperature R134a (or other high-temperature refrigerants) to form a cascade system to expand application scenarios. However, the implementation of this solution has brought about problems such as increased system complexity, increased failure rate, and decreased stability. In addition, the use of high-temperature refrigerants partially offsets the environmental friendliness of the CO system, which is not conducive to energy conservation and environmental protection. Summary of the invention

[0005] In view of this, the present invention provides an air source heat pump system and a control method thereof to solve the problems of complex structure, high failure rate and poor stability of the heat pump system in the prior art.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides an air source heat pump system, which is suitable for a single low-temperature refrigerant, and includes: a compressor, a first heat exchanger, a second heat exchanger, a mixing tube group and a heat dissipation device; the compressor is suitable for compressing and heating the refrigerant; the compressor is arranged between the first heat exchanger and the second heat exchanger, the first port of the compressor is connected to the first heat exchanger, the second port of the compressor is connected to the second heat exchanger, the first heat exchanger and the second heat exchanger are connected, and the refrigerant circulates between the compressor, the first heat exchanger and the second heat exchanger to form a gas circulation loop; the heat dissipation device is connected to the second heat exchanger through the mixing tube group, the heat exchange fluid circulates in the second heat exchanger, the mixing tube group and the heat dissipation device to form a liquid circulation loop, the mixing tube group is provided with a temperature return pipe, one end of the temperature return pipe is connected to the water outlet end of the second heat exchanger, and the other end flows back to the water inlet end of the second heat exchanger, and the temperature return pipe is arranged in parallel with the second heat exchanger; the gas circulation loop and the liquid circulation loop are isolated for heat exchange in the second heat exchanger.

[0008] The invention has the following advantages: the refrigerant circulates between the compressor, the first heat exchanger and the second heat exchanger to form a gas circulation loop, the heat exchange fluid circulates in the second heat exchanger, the mixing tube group and the heat dissipation device to form a liquid circulation loop, the gas circulation loop and the liquid circulation loop are separated for heat exchange in the second heat exchanger, the mixing tube group is provided with a temperature return pipe, and the temperature return pipe is arranged in parallel with the second heat exchanger. Through the arrangement of the temperature return pipe, a variety of supply and return water temperature differences can be achieved, thereby meeting the needs under various temperature environments, overcoming the condition that low-temperature refrigerants need to be used in a cascade heat pump system. The air source heat pump system can realize the application of a single low-temperature refrigerant, simplify the system structure, reduce the failure rate and improve stability.

[0009] According to the first aspect of the present invention, the second heat exchanger is provided with a first inlet, a second inlet, a first outlet and a second outlet, the first inlet is connected to the first outlet, and the second inlet is connected to the second outlet;

[0010] The mixing pipe group includes a water supply pipe and a return pipe, one end of the water supply pipe is connected to the second outlet, the other end of the water supply pipe is connected to the water inlet end of the heat dissipation device, one end of the return pipe is connected to the second inlet, and the other end of the return pipe is connected to the water outlet end of the heat dissipation device; one end of the temperature return pipe is connected to the return pipe through the first valve body, and the other end of the temperature return pipe is connected to the water supply pipe;

[0011] The heat exchange fluid circulates in the second heat exchanger, the water supply pipe, the heat dissipation device and the return pipe to form a first loop, and the heat exchange fluid circulates between the temperature return pipe, the water supply pipe, the heat dissipation device and the return pipe to form a second loop.

[0012] According to the first aspect of the present invention, the mixing tube group also includes a first valve body, which is arranged on the return pipe, and the first valve body includes a first passage that allows the return pipe to be connected, and a second passage that allows the temperature return pipe and the return pipe to be connected.

[0013] According to an embodiment of the first aspect of the present invention, the air source heat pump system also includes a communicatively connected controller and a first temperature detection component, wherein the first temperature detection component is arranged on the liquid circulation loop, and the first temperature detection component is suitable for detecting the temperature of the heat exchange fluid in the first loop and the second loop, and feeding back to the controller to control the opening of the first valve body.

[0014] According to an embodiment of the first aspect of the present invention, the first temperature detection component includes a first temperature sensor, a second temperature sensor and a third temperature sensor, the first temperature sensor and the second temperature sensor are both arranged on the water supply pipe, the third temperature sensor is arranged on the return pipe, the first temperature sensor is arranged close to the second heat exchanger, the second temperature sensor is arranged close to the water inlet end of the heat dissipation device, and the third temperature sensor is arranged close to the water outlet end of the heat dissipation device and is located between the first valve body and the heat dissipation device.

[0015] According to an embodiment of the first aspect of the present invention, the air source heat pump system further comprises a driving pump arranged in the liquid circulation loop, and the driving pump is arranged close to the water outlet end of the heat dissipation device.

[0016] According to an embodiment of the first aspect of the present invention, the air source heat pump system also includes a second temperature detection component communicatively connected to the controller, the second temperature component is arranged on the gas circulation loop, the second temperature detection component includes an ambient temperature sensor and a fourth temperature sensor, the ambient temperature sensor is suitable for detecting the ambient temperature of the first heat exchanger, and the fourth temperature sensor is suitable for detecting the temperature parameters of the refrigerant in the first heat exchanger.

[0017] According to an embodiment of the first aspect of the present invention, a gas-liquid separator is provided between the first heat exchanger and the compressor, a low-pressure control module is provided between the first port of the compressor and the gas-liquid separator, the low-pressure control module includes an intake temperature sensor, a low-pressure control valve and a first pressure sensor which are arranged in sequence from far to near close to the first port; a high-pressure control module is provided between the second port of the compressor and the second heat exchanger, the high-pressure control module includes a second pressure sensor, a high-pressure control valve and an exhaust temperature sensor which are first arranged in sequence from far to near close to the second port.

[0018] In a second aspect, the present invention further provides a control method for an air source heat pump system, comprising the following steps:

[0019] According to the use environment, set the target supply and return water temperature difference and target water supply temperature;

[0020] The third temperature sensor and the second temperature sensor detect the return water temperature and the supply water temperature during the operation of the system and feed them back to the controller, and the controller calculates and obtains the instantaneous supply and return water temperature difference;

[0021] When the instantaneous supply and return water temperature difference is greater than the target supply and return water temperature difference, the controller controls the driving pump to increase its speed;

[0022] When the instantaneous supply and return water temperature difference is less than the target supply and return water temperature difference, the controller controls the driving pump to reduce its speed;

[0023] The instantaneous supply and return water temperature difference is equal to the target supply and return water temperature difference, and the controller controls the driving pump speed to remain unchanged.

[0024] In a second aspect, the present invention further provides another control method for an air source heat pump system, comprising the following steps:

[0025] According to the use environment, the third temperature sensor detects the return temperature during the operation of the system and feeds back to the controller, and the controller sets the target water outlet temperature according to the ambient temperature and the return temperature;

[0026] The first temperature sensor detects the instantaneous outlet water temperature during the operation of the system and feeds back to the controller, and the controller controls the opening of the valve in the first valve body connecting the second heat exchanger and the heat dissipation device;

[0027] The instantaneous outlet water temperature is equal to the target outlet water temperature, and the opening of the valve in the first valve body connecting the second heat exchanger and the heat dissipation device remains unchanged;

[0028] The instantaneous outlet water temperature is lower than the target outlet water temperature, and the opening of the valve in the first valve body connecting the second heat exchanger and the heat dissipation device increases;

[0029] The instantaneous outlet water temperature is greater than the target outlet water temperature, and the opening of the valve in the first valve body connecting the second heat exchanger and the heat dissipation device is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A schematic diagram of the principle of an air source heat pump system provided in an embodiment of the first aspect of the present invention;

[0032] Figure 2 This is a schematic structural diagram of the second heat exchanger provided in the embodiment of the first aspect of the present invention.

[0033] Description of reference numerals:

[0034] 1. Compressor; 2. First heat exchanger; 3. Second heat exchanger; 31. First inlet; 32. First outlet; 33. Second inlet; 34. Second outlet; 4. Mixing pipe group; 41. Water supply pipe; 42. Reflux pipe; 43. Temperature return pipe; 5. Heat dissipation device; 6. First valve body; 7. Drive pump; 8. First temperature detection component; 81. First temperature sensor; 82. Second temperature sensor; 83. Third temperature sensor; 9. Gas-liquid separator. DETAILED DESCRIPTION

[0035] 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0036] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] Reference Figure 1 As shown, in the first aspect, the present invention provides an air source heat pump system, which is suitable for a single low-temperature refrigerant, comprising: a compressor 1, a first heat exchanger 2, a second heat exchanger 3, a mixing tube group 4 and a heat dissipation device 5; the compressor 1 is suitable for compressing and heating the refrigerant; the compressor 1 is arranged between the first heat exchanger 2 and the second heat exchanger 3, the first port of the compressor 1 is connected to the first heat exchanger 2, the second port of the compressor 1 is connected to the second heat exchanger 3, the first heat exchanger 2 and the second heat exchanger 3 are connected, and the refrigerant is in the compressor 1 and the first heat exchanger 2. The heat exchange fluid circulates between the second heat exchanger 3 and the second heat exchanger 3 to form a gas circulation loop; the heat dissipation device 5 is connected with the second heat exchanger 3 through the mixing tube group 4, and the heat exchange fluid circulates in the second heat exchanger 3, the mixing tube group 4 and the heat dissipation device 5 to form a liquid circulation loop. The mixing tube group 4 is provided with a temperature return pipe 43, one end of the temperature return pipe 43 is connected with the water outlet end of the second heat exchanger 3, and the other end flows back to the water inlet end of the second heat exchanger 3. The temperature return pipe 43 is arranged in parallel with the second heat exchanger 3; the gas circulation loop and the liquid circulation loop are isolated for heat exchange in the second heat exchanger 3.

[0040] It should be noted that the condensing pressure of high-temperature refrigerants is Pk≤2~3kg / cm, and the evaporation temperature T0>0℃. Our common high-temperature refrigerants include R11 (Freon 11, CFCL3, its T0=23.7℃), R21, R114, R-245fa, R-142b, R124, its T0=23.7℃. This type of refrigerant is suitable for centrifugal refrigeration compressor 1 of air-conditioning system. Usually when the working environment is 30℃, Pk≤3.06kg / cm. R124 is widely used in high-temperature air-conditioning systems. High-temperature air-conditioning system: specially designed for high-temperature working environment, mainly used in metallurgical industry, steel mills, field operation driving and four major vehicles in coking industry, cabs, equipment operation rooms and electrical rooms with ambient temperature below 80℃, which can control the indoor temperature between 20℃-35℃. The product has the characteristics of anti-vibration, anti-dust, high temperature resistance and anti-corrosion.

[0041] The condensing pressure of medium-temperature refrigerants Pk≤20kg / cm, 0℃>T0>-60℃. Our common medium-temperature refrigerants such as R717 (ammonia, NH3), R12, R22 (Freon 22, CHClF2, difluorochloromethane), R502 (an azeotropic refrigerant composed of R22 and R115 (pentafluorochloroethane, C2F5CL)), R404A, R407C, R410A, etc., are generally used in ordinary single-stage compression and two-stage compression piston refrigeration compressors1.

[0042] The condensing pressure of high-pressure low-temperature refrigerant Pk ≥ 20kg / cm, T0 ≤ -70℃. Our common low-temperature refrigerants such as R23 (Freon 23, CHF3, trifluoromethane), R13 (CF3CL), R14 (CF4), carbon dioxide (CO2), R503, R116, ethane, ethylene, etc., this type of refrigerant is suitable for the low-temperature part of cascade refrigeration equipment or low-temperature equipment below -70℃.

[0043] Specifically, the present application is applicable to the application of a single low-temperature refrigerant in a heat pump system. Specifically, carbon dioxide (CO2) is selected as the refrigerant of the present application. The refrigerant circulates between the compressor 1, the first heat exchanger 2 and the second heat exchanger 3 to form a gas circulation loop, and the heat exchange fluid circulates in the second heat exchanger 3, the mixing tube group 4 and the heat dissipation device 5 to form a liquid circulation loop. In the present application, the heat exchange fluid is water, and the gas circulation loop and the liquid circulation loop are isolated for heat exchange in the second heat exchanger 3. The mixing tube group 4 is provided with a temperature return pipe 43, and the temperature return pipe 43 is arranged in parallel with the second heat exchanger 3. Through the arrangement of the temperature return pipe 43, a variety of supply and return water temperature differences are achieved, thereby meeting the needs under various temperature environments, overcoming the condition that the low-temperature refrigerant needs to be used in a cascade heat pump system. The air source heat pump system can realize the application of a single low-temperature refrigerant, simplify the system structure, reduce the failure rate, and improve stability.

[0044] Here’s how this application works:

[0045] After passing through the first heat exchanger 2, the refrigerant becomes a low-temperature, low-pressure gaseous refrigerant. After the compressor 1 compresses the low-temperature, low-pressure gaseous refrigerant, it forms a high-temperature, high-pressure liquid refrigerant. The high-temperature, high-pressure liquid refrigerant enters the second heat exchanger 3 to exchange heat with the heat exchange fluid, thereby increasing the temperature of the heat exchange fluid from the second heat exchanger 3. The high-temperature heat exchange fluid flows out of the second heat exchanger 3 and enters the heat dissipation device 5. After the heat is dissipated by the heat dissipation device 5, the temperature of the heat exchange fluid is reduced and then circulates through the second heat exchanger 3 to exchange heat with the heat exchange fluid again. The refrigerant exchanges heat to form a liquid circulation loop; by setting a temperature return pipe 43, one end of the temperature return pipe 43 is connected to the water outlet of the second heat exchanger 3, and the other end flows back to the water inlet of the second heat exchanger 3, and the temperature return pipe 43 is set in parallel with the second heat exchanger 3; so that a part of the medium-temperature heat exchange fluid flowing out of the heat dissipation device 5 is mixed with the high-temperature heat exchange fluid flowing out of the second heat exchanger 3, and then re-enters the heat dissipation device 5, and the other part of the medium-temperature heat exchange fluid flowing out of the heat dissipation device 5 is heated and pressurized in the second heat exchanger 3. The refrigerant that completes the heat exchange in the second heat exchanger 3 flows back to the first heat exchanger 2 and changes back to a low-temperature and low-pressure gaseous refrigerant after heat exchange, and flows back to the compressor 1 to form a gas circulation loop.

[0046] The provision of the return pipe 43 solves the problem that a single low-temperature refrigerant in a heat pump system has limitations in large temperature difference application scenarios and low efficiency in small temperature difference application scenarios, and realizes the adjustment of multiple temperature differences. Specifically, the adjustment of multiple temperature differences can be achieved by setting the pipe diameter of the return pipe 43 or by setting the valve opening.

[0047] Reference Figure 2 As shown, in the embodiment of the first aspect of the present invention, the second heat exchanger 3 is provided with a first inlet 31, a second inlet 33, a first outlet 32 ​​and a second outlet 34, the first inlet 31 is connected to the first outlet 32, and the second inlet 33 is connected to the second outlet 34;

[0048] The mixing tube group 4 includes a water supply pipe 41 and a return pipe 42. One end of the water supply pipe 41 is connected to the second outlet 34, and the other end of the water supply pipe 41 is connected to the water inlet end of the heat dissipation device 5. One end of the return pipe 42 is connected to the second inlet 33, and the other end of the return pipe 42 is connected to the water outlet end of the heat dissipation device 5. One end of the return pipe 43 is connected to the return pipe 42 through the first valve body 6, and the other end of the return pipe 43 is connected to the water supply pipe 41.

[0049] The heat exchange fluid circulates in the second heat exchanger 3, the water supply pipe 41, the heat dissipation device 5 and the return pipe 42 to form a first loop, and the heat exchange fluid circulates between the temperature return pipe 43, the water supply pipe 41, the heat dissipation device 5 and the return pipe 42 to form a second loop.

[0050] Specifically, the first inlet 31 of the second heat exchanger 3 is connected to the first outlet 32, the second inlet 33 and the second outlet 34 are connected, wherein the first port of the compressor 1 is connected to the outlet end of the first heat exchanger 2, the second port of the compressor 1 is connected to the first inlet 31 of the second heat exchanger 3, and the air inlet end of the first heat exchanger 2 is connected to the first outlet 32 ​​of the second heat exchanger 3 to form a gas circulation loop; the mixing pipe group 4 includes a water supply pipe 41 and a return pipe 42, wherein one end of the water supply pipe 41 is connected to the second outlet 34 The other end of the water supply pipe 41 is connected with the water inlet end of the heat dissipation device 5, one end of the return pipe 42 is connected with the second inlet 33, the other end of the return pipe 42 is connected with the water outlet end of the heat dissipation device 5, the return pipe 43 connects the water supply pipe 41 and the return pipe 42, the heat exchange fluid circulates in the second heat exchanger 3, the water supply pipe 41, the heat dissipation device 5 and the return pipe 42 to form a first loop, and the heat exchange fluid circulates among the return pipe 43, the water supply pipe 41, the heat dissipation device 5 and the return pipe 42 to form a second loop.

[0051] In the first aspect of the embodiment of the present invention, the mixing tube group 4 also includes a first valve body 6, which is arranged on the return pipe 42, and the first valve body 6 includes a first passage that makes the return pipe 42 conductive, and a second passage that makes the return pipe 43 and the return pipe 42 conductive.

[0052] Specifically, the first valve body 6 is a three-way valve, wherein the first passage is connected to the return pipe 42, and the second passage is connected to the return pipe 42 and the temperature return pipe 43. The supply and return water temperature difference is adjusted by adjusting the opening of the first passage and the second passage.

[0053] In the first aspect of the embodiment of the present invention, the air source heat pump system also includes a controller and a first temperature detection component 8 that are communicatively connected. The first temperature detection component 8 is arranged on the liquid circulation loop. The first temperature detection component 8 is suitable for detecting the temperature of the heat exchange fluid in the first loop and the second loop, and feeding back to the controller to control the opening of the first valve body 6.

[0054] Specifically, the controller is communicatively connected with the first temperature detection component 8, wherein the first temperature detection component 8 is arranged on the liquid circulation loop, and the first temperature detection component 8 detects the temperature of the heat exchange fluid in the first loop and the second loop, including the initial outlet water temperature flowing out of the second heat exchanger 3, the supply water temperature before entering the heat dissipation device 5, and the return temperature flowing out of the heat dissipation device 5 respectively; through the detected temperature of the heat exchange fluid, combined with the ambient temperature and the required supply and return water temperature difference, the opening of the first valve body 6 is adjusted by the controller, including adjusting the opening of the first passage and the opening of the second passage, thereby realizing the adjustment of the supply and return water temperature difference, so that the air source heat pump system using a single low-temperature refrigerant can automatically adjust between application environments with large temperature difference and small temperature difference, thereby improving the stability and applicability of the system.

[0055] The first temperature detection component 8 includes a first temperature sensor 81, a second temperature sensor 82 and a third temperature sensor 83. The first temperature sensor 81 and the second temperature sensor 82 are both arranged on the water supply pipe 41, and the third temperature sensor 83 is arranged on the return pipe 42. The first temperature sensor 81 is arranged close to the second heat exchanger 3, the second temperature sensor 82 is arranged close to the water inlet end of the heat dissipation device 5, and the third temperature sensor 83 is arranged close to the water outlet end of the heat dissipation device 5 and is located between the first valve body 6 and the heat dissipation device 5.

[0056] Specifically, the first temperature detection component 8 includes a first temperature sensor 81, a second temperature sensor 82 and a third temperature sensor 83, wherein the first temperature sensor 81 and the second temperature sensor 82 are both arranged on the water supply pipe 41, the first temperature sensor 81 is arranged close to the second heat exchanger 3 to detect the initial water outlet temperature, the second temperature sensor 82 is arranged close to the heat dissipation device 5 to detect the water supply temperature, wherein the other end of the return pipe 43 is located between the first temperature sensor 81 and the second temperature sensor 82; the third temperature sensor 83 is arranged on the return pipe 42 and close to the water outlet end of the heat dissipation device 5, and the third temperature sensor 83 is located at the rear end of the first valve body 6 to accurately detect the reflux temperature.

[0057] In the first embodiment of the present invention, the air source heat pump system further includes a driving pump 7 arranged in the liquid circulation loop, and the driving pump 7 is arranged close to the water outlet end of the heat dissipation device 5 .

[0058] Specifically, a driving pump 7 is provided on the reflux pipe 42, and the driving pump 7 is a circulation pump. By setting the driving pump 7 and adjusting the rotation speed of the driving pump 7, the flow rate and flow velocity of the heat exchange fluid in the liquid circulation loop can be adjusted, thereby achieving adjustment and adaptation to application environments with large temperature differences and application environments with small temperature differences.

[0059] In the first aspect embodiment of the present invention, the air source heat pump system also includes a second temperature detection component that is communicatively connected to the controller, the second temperature component is arranged on the gas circulation loop, the second temperature detection component includes an ambient temperature sensor and a fourth temperature sensor, the ambient temperature sensor is suitable for detecting the ambient temperature of the first heat exchanger 2, and the fourth temperature sensor is suitable for detecting the temperature parameters of the refrigerant in the first heat exchanger 2.

[0060] Specifically, the first heat exchanger 2 is an evaporator, a coil is provided on the outer periphery of the evaporator, and the refrigerant flows in the coil. The second temperature detection component includes an ambient temperature sensor and a fourth temperature sensor, wherein the ambient temperature sensor is provided on the outside of the first heat exchanger 2 to be suitable for detecting the ambient temperature in which the air source heat pump system works, and the fourth temperature sensor is provided on the coil to be suitable for detecting the temperature parameters of the refrigerant in the coil.

[0061] It is understandable that a fan is provided at a position opposite to the first heat exchanger 2. The fan is provided to cool the refrigerant or to avoid frost on the first heat exchanger 2, thereby improving defrosting efficiency.

[0062] In the first aspect of the embodiment of the present invention, a gas-liquid separator 9 is provided between the first heat exchanger 2 and the compressor 1, and a low-pressure control module is provided between the first port of the compressor 1 and the gas-liquid separator 9, and the low-pressure control module includes an intake temperature sensor, a low-pressure control valve and a first pressure sensor which are arranged in sequence from far to near close to the first port; a high-pressure control module is provided between the second port of the compressor 1 and the second heat exchanger 3, and the high-pressure control module includes a second pressure sensor, a high-pressure control valve and an exhaust temperature sensor which are first arranged from far to near close to the second port.

[0063] Specifically, a gas-liquid separator 9 is provided between the first heat exchanger 2 and the compressor 1 to prevent liquid from entering the compressor 1 and causing damage to the compressor 1, so as to improve the stability of the operation of the air source heat pump system. It is understandable that the operating state of the refrigerant is detected by the low-pressure control module and the high-pressure control module, thereby realizing intelligent regulation and control of the compressor 1.

[0064] In a second aspect, the present invention further provides a control method for an air source heat pump system, comprising the following steps:

[0065] According to the use environment, set the target supply and return water temperature difference and target water supply temperature;

[0066] The third temperature sensor 83 and the second temperature sensor 82 detect the return water temperature and the supply water temperature during the operation of the system and feed them back to the controller, which calculates and obtains the instantaneous supply and return water temperature difference;

[0067] When the instantaneous supply and return water temperature difference is greater than the target supply and return water temperature difference, the controller controls the driving pump 7 to increase its speed;

[0068] When the instantaneous supply and return water temperature difference is less than the target supply and return water temperature difference, the controller controls the driving pump 7 to reduce its speed;

[0069] The instantaneous supply and return water temperature difference is equal to the target supply and return water temperature difference, and the controller controls the speed of the driving pump 7 to remain unchanged.

[0070] Specifically, according to the set target water supply temperature and in combination with the use environment, the target supply and return water temperature difference is set, and the return temperature and water supply temperature during the system operation are obtained through the third temperature sensor 83 and the second temperature sensor 82. The controller obtains the parameters and calculates the instantaneous supply and return water temperature difference during the system operation. Based on the comparison between the instantaneous supply and return water temperature difference and the target supply and return water temperature difference, the operating efficiency of the drive pump 7 is controlled, and the speed of the drive pump 7 is controlled.

[0071] It should be noted that a steady-state error range can be set to avoid frequent adjustment of the driving pump 7 and provide stability in system operation. Specifically, the steady-state temperature difference range is ±0.2°C.

[0072] On the basis of increasing the steady-state temperature difference, when the instantaneous supply and return water temperature difference is greater than the target supply and return water temperature difference, the controller controls the speed of the driving pump 7 to increase; when the instantaneous supply and return water temperature difference is less than the target supply and return water temperature difference, the controller controls the speed of the driving pump 7 to decrease; when the instantaneous supply and return water temperature difference is equal to the target supply and return water temperature difference, the controller controls the speed of the driving pump 7 to remain unchanged.

[0073] In a second aspect, the present invention further provides another control method for an air source heat pump system, comprising the following steps:

[0074] According to the use environment, the third temperature sensor 83 detects the return temperature during the operation of the system and feeds it back to the controller, and the controller sets the target water outlet temperature according to the ambient temperature and the return temperature;

[0075] The first temperature sensor 81 detects the instantaneous outlet water temperature during the operation of the system and feeds back to the controller, and the controller controls the valve opening in the first valve body 6 connecting the second heat exchanger 3 and the heat dissipation device 5;

[0076] The instantaneous outlet water temperature is equal to the target outlet water temperature, and the valve opening in the first valve body 6 connecting the second heat exchanger 3 and the heat dissipation device 5 remains unchanged;

[0077] When the instantaneous outlet water temperature is lower than the target outlet water temperature, the opening of the valve in the first valve body 6 connecting the second heat exchanger 3 and the heat dissipation device 5 increases;

[0078] The instantaneous outlet water temperature is greater than the target outlet water temperature, and the opening of the valve in the first valve body 6 connecting the second heat exchanger 3 and the heat dissipation device 5 is reduced.

[0079] Specifically, the target outlet water temperature is obtained by designing a simulation table based on the ambient temperature and return water temperature. The preset value in the simulation table is the optimal value obtained by laboratory debugging. Different products are different. The following simulation table is only for illustration. When the ambient temperature and return water temperature are between the preset points, the control system automatically calculates the optimal outlet water temperature using interpolation:

[0080] Table 1: Return water temperature design calculation table (unit: °C)

[0081]

[0082] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. An air source heat pump system suitable for a single low temperature grade refrigerant, characterized in that: include: A compressor (1), adapted to compress and heat a refrigerant; a first heat exchanger (2) and a second heat exchanger (3), the compressor (1) being arranged between the first heat exchanger (2) and the second heat exchanger (3), the first port of the compressor (1) being in communication with the first heat exchanger (2), the second port of the compressor (1) being in communication with the second heat exchanger (3), the first heat exchanger (2) being in communication with the second heat exchanger (3), the refrigerant circulates between the compressor (1), the first heat exchanger (2) and the second heat exchanger (3) to form a gas circulation loop; A mixing tube group (4) and a heat dissipation device (5), wherein a heat exchange fluid flows in the mixing tube group (4), the heat dissipation device (5) is connected to the second heat exchanger (3) through the mixing tube group (4), the heat exchange fluid circulates in the second heat exchanger (3), the mixing tube group (4) and the heat dissipation device (5) to form a liquid circulation loop, the mixing tube group (4) is provided with a temperature return pipe (43), one end of the temperature return pipe (43) is connected to the water outlet end of the second heat exchanger (3), and the other end flows back to the water inlet end of the second heat exchanger (3), and the temperature return pipe (43) is arranged in parallel with the second heat exchanger (3); The gas circulation loop and the liquid circulation loop are isolated from each other for heat exchange in the second heat exchanger (3).

2. The air source heat pump system according to claim 1, characterized in that: The second heat exchanger (3) is provided with a first inlet (31), a second inlet (33), a first outlet (32) and a second outlet (34), wherein the first inlet (31) is in communication with the first outlet (32), and the second inlet (33) is in communication with the second outlet (34); The mixing tube group (4) comprises a water supply pipe (41) and a return pipe (42); one end of the water supply pipe (41) is connected to the second outlet (34), and the other end of the water supply pipe (41) is connected to the water inlet of the heat dissipation device (5); one end of the return pipe (42) is connected to the second inlet (33), and the other end of the return pipe (42) is connected to the water outlet of the heat dissipation device (5); one end of the temperature return pipe (43) is connected to the return pipe (42), and the other end of the temperature return pipe (43) is connected to the water supply pipe (41); The heat exchange fluid circulates in the second heat exchanger (3), the water supply pipe (41), the heat dissipation device (5) and the return pipe (42) to form a first loop, and the heat exchange fluid circulates between the temperature return pipe (43), the water supply pipe (41), the heat dissipation device (5) and the return pipe (42) to form a second loop.

3. The air source heat pump system according to claim 2, characterized in that: The mixing tube group (4) also includes a first valve body (6), which is arranged on the return pipe (42), and the first valve body (6) includes a first passage that allows the return pipe (42) to be conductive, and a second passage that allows the return pipe (43) and the return pipe (42) to be conductive.

4. The air source heat pump system according to claim 3, characterized in that: It also includes a controller and a first temperature detection component (8) that are communicatively connected. The first temperature detection component (8) is arranged on the liquid circulation loop. The first temperature detection component (8) is suitable for detecting the temperature of the heat exchange fluid in the first loop and the second loop, and feeding back to the controller to control the opening of the first valve body (6).

5. The air source heat pump system according to claim 4, characterized in that: The first temperature detection component (8) comprises a first temperature sensor (81), a second temperature sensor (82) and a third temperature sensor (83); the first temperature sensor (81) and the second temperature sensor (82) are both arranged on the water supply pipe (41); the third temperature sensor (83) is arranged on the return pipe (42); the first temperature sensor (81) is arranged close to the second heat exchanger (3); the second temperature sensor (82) is arranged close to the water inlet end of the heat dissipation device (5); and the third temperature sensor (83) is arranged close to the water outlet end of the heat dissipation device (5) and is located between the first valve body (6) and the heat dissipation device (5).

6. The air source heat pump system according to any one of claims 1 to 5, characterized in that: It also includes a driving pump (7) arranged in the liquid circulation loop, and the driving pump (7) is arranged close to the water outlet end of the heat dissipation device (5).

7. The air source heat pump system according to claim 4 or 5, characterized in that: It also includes a second temperature detection component that is communicatively connected to the controller, the second temperature detection component is arranged on the gas circulation loop, the second temperature detection component includes an ambient temperature sensor and a fourth temperature sensor, the ambient temperature sensor is suitable for detecting the ambient temperature of the first heat exchanger (2), and the fourth temperature sensor is suitable for detecting the temperature parameters of the refrigerant in the first heat exchanger (2).

8. The air source heat pump system according to claim 7, characterized in that: A gas-liquid separator (9) is provided between the first heat exchanger (2) and the compressor (1); a low-pressure control module is provided between the first port of the compressor (1) and the gas-liquid separator (9); the low-pressure control module comprises an intake temperature sensor, a low-pressure control valve and a first pressure sensor which are arranged in sequence from far to near near the first port; a high-pressure control module is provided between the second port of the compressor (1) and the second heat exchanger (3); the high-pressure control module comprises a second pressure sensor, a high-pressure control valve and an exhaust temperature sensor which are arranged first in sequence from far to near near the second port.

9. A control method for an air source heat pump system, characterized in that: The following steps are involved: According to the use environment, set the target supply and return water temperature difference and target water supply temperature; The third temperature sensor (83) and the second temperature sensor (82) detect the return water temperature and the supply water temperature during the operation of the system and feed them back to the controller, and the controller calculates and obtains the instantaneous supply and return water temperature difference; When the instantaneous supply and return water temperature difference is greater than the target supply and return water temperature difference, the controller controls the driving pump (7) to increase its speed; When the instantaneous supply and return water temperature difference is less than the target supply and return water temperature difference, the controller controls the driving pump (7) to reduce its rotation speed; The instantaneous supply and return water temperature difference is equal to the target supply and return water temperature difference, and the controller controls the rotation speed of the driving pump (7) to remain unchanged.

10. A control method for an air source heat pump system, characterized in that: The following steps are involved: According to the use environment, the third temperature sensor (83) detects the return temperature during the operation of the system and feeds back to the controller, and the controller sets the target water outlet temperature according to the ambient temperature and the return temperature; The first temperature sensor (81) detects the instantaneous outlet water temperature during the operation of the system and feeds back to the controller, and the controller controls the opening of the valve in the first valve body (6) connecting the second heat exchanger (3) and the heat dissipation device (5); The instantaneous outlet water temperature is equal to the target outlet water temperature, and the opening of the valve in the first valve body (6) connecting the second heat exchanger (3) and the heat dissipation device (5) remains unchanged; The instantaneous outlet water temperature is lower than the target outlet water temperature, and the opening of the valve in the first valve body (6) connecting the second heat exchanger (3) and the heat dissipation device (5) increases; When the instantaneous outlet water temperature is greater than the target outlet water temperature, the opening of the valve in the first valve body (6) connecting the second heat exchanger (3) and the heat dissipation device (5) is reduced.

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