An oil-cooled heat recovery air preheating type heat pump unit

Abstract

An oil-cooled heat recovery air preheating type heat pump unit includes a compressor, a four-way valve, a first heat exchanger and a second heat exchanger, and also includes an oil circulation system and a water circulation system. The oil circulation system includes an oil separator and an oil cooler. The oil separator is installed between the fourth interface of the four-way valve and the compressor. The oil separator is also connected to the oil cooler. The water circulation system includes a water tank, a liquid distributor, an air preheating heat exchanger, a first water pump and a second water pump. The water in the water tank can be pumped to the oil cooler by the first water pump for heat exchange and then transported back to the water tank. The water tank outlet is connected to the second water pump. The water flow to the air preheating heat exchanger or the liquid distributor is controlled by a switch behind the second water pump. The heat pump unit can use the heat energy generated by the lubrication system and other heat energy to provide a preheating function for the heat pump unit in winter to improve the performance of the unit and save energy.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pumps, and in particular to an oil-cooled heat recovery air preheating type heat pump unit. Background Art

[0002] In existing technologies, air-source heat pumps absorb heat from the outdoor air through their finned heat exchange evaporators in low winter temperatures. This frost can reduce heat exchange efficiency and compressor suction temperatures, leading to excessively high compressor pressure ratios and negatively impacting compressor and system operation. Frequently activating defrost mode can impact system operation and heating comfort, and in severe cases, can even cause the heat pump to stop functioning.

[0003] Moreover, the existing fin evaporative heat exchanger only exchanges heat with the air and has no other heat source input. In the low temperature environment of northern winter, the heat exchange temperature difference of the heat exchanger becomes smaller, further reducing the heat exchange efficiency of the heat exchanger, thereby affecting the heating effect of the user and failing to achieve the ideal heating effect.

[0004] The lubrication system is a crucial component of a heat pump system. Heat pump systems require continuous high pressure during compressor operation, generating significant heat and gradually increasing the temperature of the lubricating oil. Calculations show that extended operation of a screw compressor can produce exhaust temperatures of 85°C to 102°C. This elevated oil temperature, which stores significant heat energy, is a crucial component of any heat pump system. However, if this heat is not dissipated promptly, the system oil's viscosity decreases as the temperature rises, and the oil pressure falls below operating requirements. To ensure safe and reliable operation of the unit, the oil temperature must be kept within a specified range. Summary of the Invention

[0005] The purpose of the present invention is to address the problems that frequent defrosting of existing heat pump units in winter will affect the system operation and heating comfort, and the increase in oil temperature after the lubrication system has worked for a long time will affect the safe operation of the unit. An oil-cooled heat recovery air preheating heat pump unit is proposed, which utilizes the heat energy generated by the lubrication system and other heat energy to provide a preheating function for the heat pump unit in winter, thereby improving the performance of the unit and saving energy.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0007] An oil-cooled heat recovery air preheating heat pump unit includes a compressor, a four-way valve, a first heat exchanger, a second heat exchanger, an oil circulation system, and a water circulation system. The compressor's exhaust port is connected to the first port of the four-way valve, and the second and third ports of the four-way valve are connected to the first and second heat exchangers, respectively. A bidirectional throttling device is provided between the first and second heat exchangers. The four-way valve can be used to switch between summer cooling mode and winter heating mode. In cooling mode, the first heat exchanger serves as a condenser and the second heat exchanger serves as an evaporator. In heating mode, the second heat exchanger serves as a condenser and the first heat exchanger serves as an evaporator.

[0008] The oil circulation system includes an oil separator and an oil cooler. The oil separator is installed between the fourth interface of the four-way valve and the compressor, and can separate the lubricating oil in the high-pressure steam discharged by the compressor. An oil cooler is also connected to the back of the oil separator, and the oil cooler is connected to the compressor.

[0009] The water circulation system includes a water tank, a liquid distributor, an air preheating heat exchanger, a first water pump and a second water pump. The water in the water tank can be pumped to the oil cooler by the first water pump to exchange heat with the high-temperature lubricating oil and then transported back to the water tank. The water tank outlet is connected to the second water pump, and the air preheating heat exchanger and the liquid distributor are respectively connected to the back of the second water pump. Switches are respectively provided on the water pipes between the water tank and the air preheating heat exchanger and the liquid distributor. The air preheating heat exchanger is arranged at the air inlet.

[0010] In the heat pump unit described above, the water tank is further connected to a solar collector to further heat the water in the water tank. A control switch is provided between the water tank and the solar collector. The control switch is turned on in winter heating mode and turned off in summer cooling mode.

[0011] In the heat pump unit as described above, the air preheating heat exchanger can be disassembled from the air inlet. It can be temporarily removed when used in the summer and installed again when used in the winter.

[0012] As described above, the heat pump unit has a detachable water tank cover on the water tank, which can be covered on the water tank to keep the hot water in the water tank warm during winter operation and can be removed during summer operation.

[0013] In the heat pump unit as described above, the first heat exchanger is located indoors, the second heat exchanger is located outdoors, and the second heat exchanger includes a fin-tube heat exchanger and an evaporative cooling coil.

[0014] In the heat pump unit as described above, the throttling device includes a first throttle valve and a second throttle valve.

[0015] In the heat pump unit described above, the water line between the water tank and the air preheating heat exchanger and liquid distributor is controlled by a solenoid valve. When the four-way valve is set to cooling mode, the water line between the water tank and the liquid distributor is open. When the four-way valve is set to heating mode, the water line between the water tank and the air preheating heat exchanger is open.

[0016] In the heat pump unit described above, a first insulation layer is provided on the outside of the water tank, and a second insulation layer is provided on the heat pump unit housing except for the air inlet and outlet. This allows the interior of the heat pump unit to function as a preheating tank, with heat dissipated by various devices within the unit within the insulation layer. This heat can then be used to assist in preheating the air, improving winter heating efficiency.

[0017] Preferably, the thermal insulation materials of the first thermal insulation layer and the second thermal insulation layer include polyurethane thermal insulation materials.

[0018] The beneficial effects of the present invention are:

[0019] 1. The heat pump unit disclosed in the present invention adopts multi-energy complementary technology to recover the waste heat from the compressor and combine it with solar energy to produce hot water. The air is preheated by setting an air preheating heat exchanger at the air inlet, which indirectly increases the ambient temperature of the heat pump operation in winter, improves the performance of the unit, and saves energy.

[0020] 2. The heat pump unit disclosed in this invention can fully recover waste heat generated by the screw unit in summer, providing a heat source for nearby domestic hot water supply, achieving multi-purpose use. Furthermore, the unit utilizes evaporative cooling technology in summer, rapidly removing heat from the condenser through phase change evaporation, resulting in high unit efficiency.

[0021] 3. The heat pump unit disclosed in the present invention, through innovative unit structure, achieves insulation at the unit's air inlet and outlet. The inlet and outlet preheating heat exchangers and the upper cover of the insulated water tank are removable, facilitating switching between winter and summer operating modes. In winter, the insulated water tank is used to store heat for stable air preheating. In summer, it serves as a water pool for the evaporative cooling condenser. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] By reading the detailed description of the preferred embodiment below, the solutions and advantages of the present application will become clear to those skilled in the art. The accompanying drawings are only for illustrating the preferred embodiment and are not to be considered as limiting the present invention.

[0023] In the attached figure:

[0024] Figure 1 This is a structural diagram of the heat pump unit of Example 1;

[0025] Figure 2 This is the operating principle diagram of the heat pump unit in Example 1;

[0026] The components represented by the reference numerals in the figure are:

[0027] 1. Axial-flow fan, 2. First heat exchanger, 3. Second heat exchanger, 4. Liquid distributor, 5. Evaporative cooling coil, 6. Air preheating heat exchanger, 7. Water inlet, 8. Water tank cover, 9. Water tank, 10. First insulation layer, 11. Second insulation layer, 12. First throttle valve, 13. Second throttle valve, 14. Four-way valve, 15. Oil separator, 16. Screw compressor, 17. Oil cooler, 18. First water pump, 19. Second water pump, 20. Third water pump, 21. Solar collector. DETAILED DESCRIPTION

[0028] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. It should be noted that these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. The present disclosure can be implemented in various forms and should not be limited by the embodiments described herein.

[0029] Example 1

[0030] See also Figure 1 and Figure 2 , Figure 1 and Figure 2 This is a schematic diagram of the structure and operating principle of an oil-cooled heat recovery air preheating heat pump unit according to this embodiment. It includes a screw compressor 16, a four-way valve 14, a first heat exchanger 2, a second heat exchanger 3, an oil circulation system, and a water circulation system. The exhaust port of the screw compressor 16 is connected to the first interface of the four-way valve 14. The second and third interfaces of the four-way valve 14 are respectively connected to the first heat exchanger 2 and the second heat exchanger 3. The first heat exchanger 2 is located indoors, and the second heat exchanger 3 is located outdoors. The second heat exchanger 3 includes a fin-tube heat exchanger and an evaporative cooling coil 5. An axial fan 1 is provided on top of the fin-tube heat exchanger. A bidirectional throttling device is provided between the first heat exchanger 2 and the second heat exchanger 3, namely the first throttle valve 12 and the second throttle valve 13. The four-way valve 14 can be used to switch between summer cooling mode and winter heating mode. In cooling mode, the first heat exchanger 2 serves as a condenser and the second heat exchanger 3 serves as an evaporator. In heating mode, the second heat exchanger 3 serves as a condenser and the first heat exchanger 2 serves as an evaporator.

[0031] The oil circulation system includes an oil separator 15 and an oil cooler 17. The oil separator 15 is installed between the fourth interface of the four-way valve 14 and the screw compressor 16, and can separate the lubricating oil in the high-pressure steam discharged from the screw compressor 16. The oil separator 15 is also connected to the oil cooler 17. The oil cooler 17 is connected to the screw compressor 16 to transport the cooled lubricating oil to the screw compressor 16 for use, thereby realizing the recycling of the lubricating oil.

[0032] The water circulation system includes a water tank 9, a liquid distributor 4, an air preheating heat exchanger 6, a first water pump 18, and a second water pump 19. Water in the water tank 9 is pumped by the first water pump 18 to an oil cooler 17 for heat exchange with high-temperature lubricating oil before being returned to the water tank 9. The outlet of the water tank 9 is connected to the second water pump 19, which is then connected to the air preheating heat exchanger 6 and the liquid distributor 4. Switches are provided on the water pipes between the water tank 9, the air preheating heat exchanger 6, and the liquid distributor 4. The switches between the water tank 9, the air preheating heat exchanger 6, and the liquid distributor 4 are controlled by solenoid valves, allowing the water flow direction to be changed between summer and winter use. When the four-way valve 14 is in cooling mode, the water pipe between the water tank 9 and the liquid distributor 4 is open. When the four-way valve 14 is in heating mode, the water pipe between the water tank 9 and the air preheating heat exchanger 6 is open.

[0033] The screw compressor 16 in this embodiment can achieve exhaust temperatures as high as 85°C to 102°C when operating for extended periods. This elevated oil temperature, which stores a significant amount of thermal energy, is utilized to cool the lubricating oil in the screw compressor 16. This waste heat is then used to convert the cold water in the water tank 9 into hot water, allowing the temperature of the converted hot water to be adjusted within a range of 50°C to 85°C.

[0034] Furthermore, the water tank 9 is provided with an interface connected to a solar thermal collector 21, which can further heat the water in the water tank 9. A third water pump 20 is connected between the water tank 9 and the solar thermal collector 21 to transport the heated hot water back to the water tank 9. A control switch is provided between the water tank 9 and the solar thermal collector 21, which is open in winter heating mode and closed in summer cooling mode.

[0035] In this embodiment, Figure 1 A diagram of the heat pump unit's winter operation structure shows the air preheating heat exchanger 6, located at the air inlet. Its specific structure can employ a finned-tube heat exchanger. During winter operation, hot water can be added to the water inlet 7 of the air preheating heat exchanger 6 to preheat the air, preventing frost on the finned-tube heat exchanger when the heat pump operates in low-temperature environments. Furthermore, the air preheating heat exchanger 6 is detachable, allowing it to be temporarily removed from the air inlet during summer use and reinstalled during winter operation.

[0036] Furthermore, the water tank 9 is located at the bottom of the heat pump unit, and a detachable water tank cover 8 is provided above it to facilitate switching between winter and summer operating modes. During winter operation, the cover can be placed on the water tank 9 to store hot water in the water tank 9 for stable air preheating. During summer operation, the cover can be removed and used as a water pool for the evaporative condenser.

[0037] Preferably, a first insulation layer 10 is provided on the outside of the water tank 9, and a second insulation layer 11 is provided on the heat pump unit housing except for the air inlet and outlet. This allows the interior of the heat pump unit to function as a preheating chamber, with heat dissipated by various devices within the unit within the insulation layer. This heat can be used to assist in preheating the air, improving winter heating efficiency. The insulation material for the first and second insulation layers 10, 11 can be polyurethane.

[0038] The heat pump unit in this embodiment has two modes: summer cooling and winter heating.

[0039] The summer heat exchanger is a pre-cooling evaporative cooling condenser. The pipeline switch between the water tank 9 and the liquid distributor 4 is turned on, and the water in the water tank 9 is used by the second water pump 19 and the liquid distributor 4 for falling film evaporation. At this time, the water tank cover 8 above the water tank 9 is removed, and the water sprayed from the liquid distributor 4 falls into the water tank 9 for recycling.

[0040] In winter, the heat exchanger functions as an air-cooled evaporator. The line between the water tank 9 and the air preheating heat exchanger 6 is opened, and the water in the water tank 9 is pumped by a second water pump 19 into the water inlet 7 of the fin-tube heat exchanger at the air inlet, preheating the air. At this point, the water in the water tank 9 is hot water, with heat derived from two sources: the first is the oil in the screw compressor 16, which is recovered through the oil separator 15 and oil cooler 17; the second is the hot water generated by the solar collector 21. Both sources of heat are used to raise the water temperature in the water tank 9.

[0041] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes, additions, subtractions, or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An oil-cooled heat recovery air preheating type heat pump unit, comprising a compressor, a four-way valve (14), a first heat exchanger (2) and a second heat exchanger (3), wherein the exhaust port of the compressor is connected to the first interface of the four-way valve (14), the second interface and the third interface of the four-way valve (14) are respectively connected to the first heat exchanger (2) and the second heat exchanger (3), and a bidirectional throttling device is provided between the first heat exchanger (2) and the second heat exchanger (3). It is characterized in that It also includes an oil circulation system and a water circulation system; The oil circulation system comprises an oil separator (15) and an oil cooler (17), wherein the oil separator (15) is installed between the fourth interface of the four-way valve (14) and the compressor, and the oil cooler (17) is connected to the rear of the oil separator (15), and the oil cooler (17) is connected to the compressor; The water circulation system comprises a water tank (9), a liquid distributor (4), an air preheating heat exchanger (6), a first water pump (18) and a second water pump (19); water in the water tank (9) can be pumped to an oil cooler (17) by the first water pump (18) for heat exchange and then transported back to the water tank (9); the outlet of the water tank (9) is connected to the second water pump (19); the rear of the second water pump (19) is respectively connected to the air preheating heat exchanger (6) and the liquid distributor (4); switches are respectively provided on the water pipes between the water tank (9) and the air preheating heat exchanger (6) and the liquid distributor (4); the air preheating heat exchanger (6) is arranged at the air inlet; The air preheating heat exchanger (6) can be removed from the air inlet; The water tank (9) is provided with a detachable water tank cover (8); A first thermal insulation layer (10) is arranged outside the water tank (9); The heat pump unit housing is provided with a second thermal insulation layer (11) except for the air inlet and the air outlet. The thermal insulation materials of the first thermal insulation layer (10) and the second thermal insulation layer (11) include polyurethane thermal insulation materials.

2. The oil-cooled heat recovery air preheating heat pump unit according to claim 1, It is characterized in that The water tank (9) is also connected to a solar heat collector (21) and can further heat the water in the water tank (9). A control switch is provided between the water tank (9) and the solar heat collector (21).

3. The oil-cooled heat recovery air preheating type heat pump unit according to claim 1, It is characterized in that The second heat exchanger (3) comprises a fin-tube heat exchanger and an evaporative cooling coil (5).

4. The oil-cooled heat recovery air preheating type heat pump unit according to claim 1, It is characterized in that The throttling device comprises a first throttle valve (12) and a second throttle valve (13).

5. The oil-cooled heat recovery air preheating type heat pump unit according to claim 1, It is characterized in that The water circuit switch between the water tank (9) and the air preheating heat exchanger (6) and the liquid distributor (4) is controlled by a solenoid valve.

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