Gas heat pump unit for achieving ultra-low temperature refrigeration and control method thereof

Abstract

The application relates to the technical field of gas heat pump, in particular to a gas heat pump unit realizing extremely low-temperature refrigeration and a control method thereof, which comprises a cooling water system, an electromagnetic control system and a heat recovery device, the electromagnetic control system is used for controlling the flow direction of refrigerant, the electromagnetic control system is connected with the heat recovery device, when the ambient temperature is lower than a set threshold value and the exhaust pressure is lower than a set threshold value, the refrigerant is branched to the heat recovery device and the cooling water system for heat exchange through the electromagnetic control system, so that the condensing pressure is improved. The high pressure of the refrigeration system is improved by using the engine cooling water heat, and the air conditioning system can safely operate in the extremely low ambient temperature.

Description

Technical Field

[0001] This application relates to the field of gas heat pump technology, and in particular to gas heat pump units and control methods for achieving ultra-low temperature cooling. Background Technology

[0002] A gas-fired heat pump is an air conditioning system that uses a gas engine to drive a compressor for both cooling and heating. By recovering waste heat from the engine, the heating effect of a gas-fired heat pump is far superior to that of a conventional electric heat pump. During cooling operation, the waste heat from the engine is directly released into the air. Air-cooled units typically cannot operate in low ambient temperatures because excessively low condensing pressure prevents the throttling components from obtaining sufficient pressure differential, rendering the evaporator ineffective and ultimately causing the compressor to become liquid-cooled.

[0003] Existing gas-fired heat pumps, when operating in low-temperature cooling conditions, suffer from insufficient pressure differential due to low condensing pressure. This prevents the throttling components from achieving adequate pressure differential, rendering the evaporator ineffective and ultimately causing liquid compression in the compressor. This makes it impossible to solve the low-temperature cooling problem. Therefore, a minimum ambient temperature is typically set for cooling; when the temperature falls below this limit, the unit will malfunction and shut down. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a gas-fired heat pump unit that achieves extremely low temperature refrigeration. By utilizing the heat from the engine cooling water to increase the high pressure of the refrigeration system, the air conditioning system can safely operate in extremely low ambient temperatures.

[0005] The technical solution provided by this invention is as follows:

[0006] A gas-fired heat pump unit for achieving ultra-low temperature cooling is characterized by comprising a cooling water system, an electromagnetic control system, and a heat recovery unit. The electromagnetic control system is used to control the refrigerant flow direction. The electromagnetic control system is connected to the heat recovery unit. When the ambient temperature is lower than a set threshold and the exhaust pressure is lower than a set threshold, the refrigerant is diverted through the electromagnetic control system to the heat recovery unit to exchange heat with the cooling water system, thereby increasing the condensing pressure.

[0007] Furthermore, the gas heat pump unit also includes a compressor, an oil separator, an air heat exchanger, a water-fluorine heat exchanger, a gas-liquid separator, an engine, and a four-way valve. The four-way valve is connected to the exhaust port of the oil separator, the inlet of the air heat exchanger, the fluorine-side outlet of the water-fluorine heat exchanger, and the inlet of the gas-liquid separator, respectively.

[0008] Furthermore, the cooling water system includes a radiator, a water pump, a first three-way valve, and a second three-way valve. The first three-way valve is connected to the engine's cooling water outlet, the water pump's inlet, and the second three-way valve. The second three-way valve is connected to the water-side inlet of the heat recovery unit, the radiator's inlet, and the first three-way valve. The electromagnetic control system includes a first solenoid valve and a second solenoid valve. The inlet of the first solenoid valve is located between the oil separator and the four-way valve. The outlet of the first solenoid valve is located between the heat recovery unit and the second solenoid valve. The second solenoid valve is located between the refrigerant-side inlet of the water-refrigerant heat exchanger and the inlet of the gas-liquid separator.

[0009] Furthermore, the outlet of the air heat exchanger is connected to the fluorine-side inlet of the water-fluorine heat exchanger, and a first electronic expansion valve is provided on the connecting pipe between the two.

[0010] Furthermore, the outlet of the gas-liquid separator is connected to the inlet of the compressor; a copper pipe is installed between the fluorine side inlet of the water-fluorine heat exchanger and the inlet of the gas-liquid separator, and a second electronic expansion valve, a heat recovery unit, and a second solenoid valve are installed sequentially on the copper pipe.

[0011] Furthermore, a pressure sensor is connected to the compressor's exhaust port to detect the exhaust pressure.

[0012] Furthermore, the air heat exchanger is equipped with a fan motor.

[0013] Furthermore, the water-side outlet of the heat recovery unit and the outlet of the radiator are both connected to the inlet of the water pump; the outlet of the water pump is connected to the engine.

[0014] Furthermore, the air inlet of the air heat exchanger is equipped with a temperature sensor for detecting the ambient temperature.

[0015] This invention also provides a control method for the above-mentioned gas-fired heat pump unit that achieves ultra-low temperature refrigeration, comprising:

[0016] Monitor ambient temperature and exhaust pressure;

[0017] When the ambient temperature is below the set threshold and the exhaust pressure is below the set threshold, the electromagnetic control system is activated, and the refrigerant is diverted through the electromagnetic control system to the heat recovery unit to exchange heat with the cooling water, thereby increasing the condensing pressure.

[0018] Beneficial effects

[0019] This invention employs an electromagnetic control system to control the refrigerant flow. During low-temperature cooling, the heat recovery unit is connected to the high-pressure side. When the condensing pressure is too low, a portion of the high-temperature, high-pressure refrigerant is diverted to the heat recovery unit to exchange heat with the cooling water, thereby increasing the condensing pressure. During heating operation, the heat recovery unit is connected to the low-pressure side, and the heat recovery unit acts as a secondary evaporator to increase the system's heating capacity. This invention utilizes the heat from the engine cooling water to increase the high pressure of the refrigeration system, enabling the air conditioning system to operate safely in extremely low ambient temperatures. Existing technologies have a minimum operating temperature of 0–5°C for cooling, while the technical solution provided by this invention can reduce the minimum operating temperature to -10°C. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the process of the present invention;

[0021] Figure 2 This is a diagram of the high-temperature refrigeration system of the present invention (To > 0°C);

[0022] Figure 3 This is a diagram of the cryogenic refrigeration system of the present invention (To≤0℃);

[0023] Figure 4 This is a diagram of the heating operation system of the present invention.

[0024] 1. Compressor; 2. Oil separator; 3. Four-way valve; 4. Air heat exchanger; 5. First electronic expansion valve (EXV1); 6. Water-fluorine heat exchanger; 7. Gas-liquid separator; 8. Engine; 9. First three-way valve (3SV1); 10. Second three-way valve (3SV2); 11. Radiator; 12. Water pump; 13. Heat recovery unit; 14. Second electronic expansion valve (EXV2); 15. First solenoid valve (SV1); 16. Second solenoid valve (SV2); 17. Fan motor; 18. Pressure sensor; 19. Temperature sensor; 20. Pulley. Detailed Implementation

[0025] Example 1

[0026] like Figures 1-4 As shown, a gas-fired heat pump unit for achieving ultra-low temperature refrigeration includes a cooling water system, an electromagnetic control system, and a heat recovery unit 13. The electromagnetic control system is used to control the flow of refrigerant. The electromagnetic control system is connected to the heat recovery unit 13. When the ambient temperature is lower than a set threshold and the exhaust pressure is lower than a set threshold, the refrigerant is diverted to the heat recovery unit 13 through the electromagnetic control system to exchange heat with the cooling water system, thereby increasing the condensing pressure.

[0027] The gas heat pump unit also includes a compressor 1, an oil separator 2, an air heat exchanger 4, a water-fluorine heat exchanger 6, a gas-liquid separator 7, an engine 8, and a four-way valve 3. The four-way valve 3 is connected to the exhaust port of the oil separator 2, the inlet of the air heat exchanger 4, the fluorine-side outlet of the water-fluorine heat exchanger 6, and the inlet of the gas-liquid separator 7, respectively.

[0028] The exhaust port of compressor 1 is connected to the inlet of oil separator 2. The exhaust port of oil separator 2 is connected to port D of four-way valve 3. The oil outlet of oil separator 2 is connected to the outlet of gas-liquid separator 7. Port E of four-way valve 3 is connected to the inlet of air heat exchanger 4. The outlet of air heat exchanger 4 is connected to the refrigerant side inlet of water-refrigerant heat exchanger 6. A first electronic expansion valve 5 is provided on the connecting pipe. The refrigerant side outlet of water-refrigerant heat exchanger 6 is connected to port C of four-way valve 3. Port S of four-way valve 3 is connected to the inlet of gas-liquid separator 7.

[0029] During cooling operation, ports D and E of the four-way valve 3 are connected, and ports S and C are connected. During heating operation, ports D and C of the four-way valve 3 are connected, and ports S and E are connected. The flow direction of the refrigerant is changed by adjusting the four-way valve. The four ports of the four-way valve are arranged in a circle and are controlled to alternately connect at intervals.

[0030] The cooling water system includes a radiator 11, a water pump 12, a first three-way valve 9, and a second three-way valve 10. The first three-way valve 9 is connected to the cooling water outlet of the engine 8, the inlet of the water pump 12, and the second three-way valve 10. The second three-way valve 10 is connected to the water-side inlet of the heat recovery unit 13, the inlet of the radiator 11, and the first three-way valve 9. The electromagnetic control system includes a first solenoid valve 15 and a second solenoid valve 16. The inlet of the first solenoid valve 15 is located between the oil separator 2 and the four-way valve 3. The outlet of the first solenoid valve 15 is located between the heat recovery unit 13 and the second solenoid valve 16. The second solenoid valve 16 is located between the refrigerant-side inlet of the water-refrigerant heat exchanger 6 and the inlet of the gas-liquid separator 7.

[0031] The outlet of the air heat exchanger 4 is connected to the refrigerant-side inlet of the water-refrigerant heat exchanger 6, and a first electronic expansion valve 5 is installed on the connecting pipe between the two. The outlet of the gas-liquid separator 7 is connected to the inlet of the compressor 1; a copper pipe is installed between the refrigerant-side inlet of the water-refrigerant heat exchanger 6 and the inlet of the gas-liquid separator 7, and a second electronic expansion valve 14, a heat recovery unit 13, and a second solenoid valve 16 are sequentially installed on the copper pipe. The opening range of the first electronic expansion valve 5 and the second electronic expansion valve 14 is 0 to 480 steps.

[0032] The compressor 1 has a pressure sensor 18 connected to its exhaust port for detecting the exhaust pressure HP. The air heat exchanger 4 is equipped with a fan motor 17. The water-side outlet of the heat recovery unit 13 and the outlet of the radiator 11 are both connected to the inlet of the water pump 12; the outlet of the water pump 12 is connected to the engine 8. The air inlet of the air heat exchanger 4 is equipped with a temperature sensor 19 for detecting the ambient temperature To.

[0033] Compressor 1 compresses the refrigerant into a high-temperature, high-pressure gaseous state, which enters oil separator 2 through the inlet. The refrigerant and lubricating oil are separated in oil separator 2. The refrigerant enters air heat exchanger 4 through four-way valve 3 from the outlet of oil separator 2, while the lubricating oil enters compressor 1 from the oil drain port of oil separator 2. The high-temperature, high-pressure gaseous refrigerant exchanges heat with air in air heat exchanger 4 and condenses into a medium-temperature, medium-pressure liquid refrigerant, which is discharged from the outlet of air heat exchanger 4. After passing through the first electronic expansion valve 5, it is throttled into a low-temperature, low-pressure gas-liquid two-phase refrigerant and enters water-fluorine heat exchanger 6. In water-fluorine heat exchanger 6, it exchanges heat with water and evaporates into a low-temperature, low-pressure gaseous refrigerant, which is discharged from the fluorine side outlet of water-fluorine heat exchanger 6. After passing through four-way valve 3, it enters gas-liquid separator 7. The refrigerant is separated in gas-liquid separator 7. The gaseous refrigerant enters compressor 1, while the liquid refrigerant remains in gas-liquid separator 7.

[0034] The engine cooling water system is connected as follows: the cooling water outlet of engine 8 is connected to port A of the first three-way valve 9; port B of the first three-way valve 9 is connected to the inlet of water pump 12; and port C is connected to port A of the second three-way valve 10. Port B of the second three-way valve 10 is connected to the water-side inlet of heat recovery unit 13; and port C is connected to the inlet of radiator 11. The water-side outlet of heat recovery unit 13 and the outlet of radiator 11 are both connected to the inlet of water pump 12. The outlet of water pump 12 is connected to the engine.

[0035] The opening degree of the three-way valve from A to B and C is adjustable, typically with 10 levels, each level representing 10% of the maximum opening. For example, level 1: opening degree from A to B = 10%, opening degree from A to C = 90%. Level 2: opening degree from A to B = 20%, opening degree from A to C = 80%.

[0036] The first electronic expansion valve 5 (EXV1) functions to throttle and reduce pressure and control flow. During cooling and heating operation, its opening is controlled by detecting the difference between the suction temperature and the evaporation temperature (suction superheat). During cooling operation, the water-refrigerant heat exchanger 6 acts as the evaporator, and the suction superheat is the difference between the suction temperature and the evaporation temperature of the water-refrigerant heat exchanger 6. During heating operation, the air heat exchanger 4 acts as the evaporator, and the suction superheat is the difference between the suction temperature and the evaporation temperature of the air heat exchanger 4. A target value for the suction superheat is typically set, for example, 5°C. When the detected value is lower than the target value, the EXV1 valve closes slightly; when the detected value is higher than the target value, the EXV1 valve opens wider.

[0037] The function of the second electronic expansion valve 14 (EXV2) is to throttle and control the flow rate. The opening degree is controlled by detecting the temperature difference between the inlet and outlet of the heat recovery unit 13. A target value is usually set, such as 10°C. When the detected value is lower than the target value, the EXV1 valve closes slightly, and when the detected value is higher than the target value, the EXV1 valve opens wider.

[0038] Example 2

[0039] A control method for a gas-fired heat pump unit that achieves ultra-low temperature refrigeration includes:

[0040] Monitor ambient temperature and exhaust pressure;

[0041] When the ambient temperature is lower than the set threshold and the exhaust pressure is lower than the set threshold, the electromagnetic control system is turned on. The refrigerant is diverted to the heat recovery unit 13 through the electromagnetic control system to exchange heat with the cooling water, thereby increasing the condensing pressure.

[0042] The control method is as follows:

[0043] 1. High-temperature cooling (To > ambient temperature threshold):

[0044] ①SV1=OFF

[0045] ②SV2=OFF

[0046] ③EXV1: Refrigeration control

[0047] ④EXV2: Close

[0048] ⑤3SV1 control:

[0049] When Tc ≤ the first water temperature threshold, 3SV1 = 10 levels; Tc is the water temperature at the engine coolant outlet.

[0050] When Tc > the first water temperature threshold, 3SV1 = 10 - (Tc - 60).

[0051] ⑥3SV2 = 0, the opening from A to C = 100%.

[0052] 2. Low-temperature refrigeration (To ≤ ambient temperature threshold)

[0053] ①SV1 control:

[0054] When HP > first exhaust pressure threshold, SV1 = OFF

[0055] When HP < the second exhaust pressure threshold, SV1 = ON

[0056] ②SV2=OFF

[0057] ③EXV1: Refrigeration control

[0058] ④EXV2 control:

[0059] When HP > first exhaust pressure threshold, EXV2 = 0 steps.

[0060] When HP < the second exhaust pressure threshold, EXV2 = 480 steps

[0061] ⑤3SV1 control:

[0062] When Tc ≤ the second water temperature threshold, 3SV1 = 10 levels.

[0063] When Tc > the second water temperature threshold, 3SV1 = 10 - (Tc - 50).

[0064] ⑥3SV2 control:

[0065] When HP > first exhaust pressure threshold and Tc ≤ first water temperature threshold, 3SV2 = 10; when Tc > first water temperature threshold, 3SV2 = 10 - (Tc - 60).

[0066] When HP < the second exhaust pressure threshold and Tc ≤ the third water temperature threshold, 3SV2 = 10; when Tc > the third water temperature threshold, 3SV2 = 10 - (Tc - 80).

[0067] During low-temperature refrigeration, the heat recovery unit is connected to the high-pressure side. When the condensing pressure is too low, a portion of the high-temperature, high-pressure refrigerant is diverted to the heat recovery unit to exchange heat with the cooling water, thereby increasing the condensing pressure.

[0068] 3. Heating Operation

[0069] ①SV1=OFF

[0070] ②SV2=ON

[0071] ③EXV1: Heating Control

[0072] ④EXV2: Heat recovery control

[0073] ⑤3SV1 control:

[0074] When Tc ≤ the first water temperature threshold, 3SV1 = 10 levels.

[0075] When Tc > the first water temperature threshold, 3SV1 = 10 - (Tc - 60).

[0076] ⑥3SV2 control:

[0077] When Tc > the fourth water temperature threshold, 3SV1 = 0.

[0078] When Tc ≤ the fourth water temperature threshold, 3SV1 = 90 - Tc.

[0079] During heating operation, the heat recovery unit is connected to the low-pressure side, and the heat recovery unit, acting as a secondary evaporator, can improve the system's heating capacity.

[0080] The ambient temperature threshold is 0±10℃; the first exhaust pressure threshold is greater than the second exhaust pressure threshold; the fourth water temperature threshold > the third water temperature threshold > the first water temperature threshold > the second water temperature threshold; the first water temperature threshold is 60±10℃; the second water temperature threshold is 50±10℃; the third water temperature threshold is 80±10℃; the fourth water temperature threshold is 90±10℃.

[0081] Example 3

[0082] This invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described in Embodiment 2.

[0083] Any part not described in this specification is prior art.

[0084] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0085] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0086] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0087] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0088] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0089] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A gas-fired heat pump unit for achieving extremely low temperature cooling, characterized in that, It includes a cooling water system, an electromagnetic control system and a heat recovery unit (13). The electromagnetic control system is used to control the flow of refrigerant. The electromagnetic control system is connected to the heat recovery unit (13). When the ambient temperature is lower than a set threshold and the exhaust pressure is lower than a set threshold, the refrigerant is diverted to the heat recovery unit (13) through the electromagnetic control system to exchange heat with the cooling water system, thereby increasing the condensing pressure. The gas heat pump unit also includes a compressor (1), an oil separator (2), an air heat exchanger (4), a water-fluorine heat exchanger (6), a gas-liquid separator (7), an engine (8), and a four-way valve (3). The four-way valve (3) is connected to the exhaust port of the oil separator (2), the inlet of the air heat exchanger (4), the fluorine side outlet of the water-fluorine heat exchanger (6), and the inlet of the gas-liquid separator (7), respectively. The cooling water system includes a radiator (11), a water pump (12), a first three-way valve (9), and a second three-way valve (10). The first three-way valve (9) is connected to the cooling water outlet of the engine (8), the inlet of the water pump (12), and the second three-way valve (10). The second three-way valve (10) is connected to the water-side inlet of the heat recovery unit (13), the inlet of the radiator (11), and the first three-way valve (9). The electromagnetic control system includes a first solenoid valve (15) and a second solenoid valve (16). The inlet of the first solenoid valve (15) is located between the oil separator (2) and the four-way valve (3). The outlet of the first solenoid valve (15) is located between the heat recovery unit (13) and the second solenoid valve (16). The second solenoid valve (16) is located between the fluorine-side inlet of the water-fluorine heat exchanger (6) and the inlet of the gas-liquid separator (7).

2. The gas-fired heat pump unit for achieving ultra-low temperature refrigeration according to claim 1, characterized in that, The outlet of the air heat exchanger (4) is connected to the fluorine side inlet of the water-fluorine heat exchanger (6), and a first electronic expansion valve (5) is provided on the connecting pipe between the two.

3. The gas-fired heat pump unit for achieving extremely low temperature refrigeration according to claim 1, characterized in that, The outlet of the gas-liquid separator (7) is connected to the inlet of the compressor (1); a copper pipe is provided between the fluorine side inlet of the water-fluorine heat exchanger (6) and the inlet of the gas-liquid separator (7), and a second electronic expansion valve (14), a heat recovery device (13) and a second solenoid valve (16) are sequentially provided on the copper pipe.

4. The gas-fired heat pump unit for achieving ultra-low temperature refrigeration according to claim 1, characterized in that, The compressor (1) is connected to a pressure sensor (18) at its exhaust port to detect the exhaust pressure.

5. The gas-fired heat pump unit for achieving ultra-low temperature refrigeration according to claim 1, characterized in that, The air heat exchanger (4) is equipped with a fan motor (17).

6. The gas-fired heat pump unit for achieving ultra-low temperature refrigeration according to claim 1, characterized in that, The water-side outlet of the heat recovery unit (13) and the outlet of the radiator (11) are both connected to the inlet of the water pump (12); the outlet of the water pump (12) is connected to the engine (8).

7. The gas-fired heat pump unit for achieving ultra-low temperature refrigeration according to claim 1, characterized in that, The air inlet of the air heat exchanger (4) is equipped with a temperature sensor (19) for detecting the ambient temperature.

8. The control method for a gas-fired heat pump unit achieving ultra-low temperature refrigeration according to claim 1, characterized in that, include: Monitor ambient temperature and exhaust pressure; When the ambient temperature is lower than the set threshold and the exhaust pressure is lower than the set threshold, the electromagnetic control system is turned on. The refrigerant is diverted to the heat recovery unit (13) through the electromagnetic control system to exchange heat with the cooling water, thereby increasing the condensing pressure.

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