Parallel ultralow-temperature variable-frequency air conditioning unit system

Abstract

The utility model discloses a parallel ultralow-temperature variable-frequency air conditioning unit system which comprises a first press, a second press, a first oil separator, a second oil separator, a first valve, a second valve, a third valve, a four-way valve, a first heat exchanger, a fourth valve, a fifth valve, a sixth valve, a first filter, a second heat exchanger, a seventh valve and a third heat exchanger. By adopting the design of the double-frequency-conversion parallel compressors, each compressor is independently provided with the oil separator and the economizer, so that accurate oil return and efficient air supply and enthalpy increase of each compressor are ensured, and the performance of the unit is improved; the evaporator, the condenser and the gas-liquid separator adopt a shared parallel system, so that sufficient heat exchange of a refrigerant and uniform and stable air suction are ensured; on the other hand, by arranging different electromagnetic valves, on one hand, whether the refrigerant flows through the economizer system of the corresponding press or not is switched, so that the system energy adjustment range and the refrigerant circulation amount are guaranteed; and secondly, the economizer is bypassed during defrosting of the unit so as to reduce the pressure drop of the system, and quick defrosting of the system is guaranteed.

Description

Technical Field

[0001] This utility model relates to the field of air conditioning system technology, and in particular to a parallel ultra-low temperature inverter air conditioning unit system. Background Technology

[0002] For heating and air conditioning projects in northern regions, the heating capacity demand of a single unit is increasing, requiring multiple compressors to meet the heating needs. However, for air-cooled heat pump water heaters, the water-side heat exchanger typically has no more than four processes. For a 25hp enthalpy-increasing compressor, to achieve a heating capacity of over 300kW at -12℃, at least six compressors are needed. The design of a six-process water-side shell-and-tube heat exchanger is quite complicated, and the system piping is also complex. Furthermore, with the promulgation of the latest national energy efficiency standards, the energy efficiency requirements for central air conditioning are becoming increasingly stringent. The comprehensive consideration includes the seasonal energy efficiency coefficients IPLV and APF. For units composed of multiple fixed-frequency compressors, the compressors cannot be unloaded, resulting in a low COP during partial load operation, making it almost impossible to meet the first-level energy efficiency standard. On the other hand, for parallel ultra-low temperature air conditioning heat pump systems, the common setup of an oil separator and economizer may lead to inaccurate and inefficient oil return and high-performance operation of the compressor. Therefore, a parallel ultra-low temperature inverter air conditioning system is needed to solve the above problems. Utility Model Content

[0003] The purpose of this utility model is to provide a parallel ultra-low temperature variable frequency air conditioning unit system to solve the defects of the common practice of setting up an oil separator and an economizer in parallel ultra-low temperature air conditioning heat pump unit systems, which may lead to the compressor not being able to accurately and efficiently return oil and operate at high performance.

[0004] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a parallel ultra-low temperature variable frequency air conditioning unit system, including a first compressor, a second compressor, a first oil separator, a second oil separator, a first valve, a second valve, a third valve, a four-way valve, a first heat exchanger, a fourth valve, a fifth valve, a sixth valve, a first filter, a second heat exchanger, a seventh valve, a third heat exchanger, an eighth valve, a ninth valve, a tenth valve, an eleventh valve, a twelfth valve, a thirteenth valve, a second filter, a balance tank, a fourth heat exchanger, a fourteenth valve, a gas-liquid separator, a fifteenth valve, and a first capillary... The first compressor's exhaust management system, consisting of the first compressor exhaust port, the first oil separator, and the first valve, is connected in parallel with the second compressor's exhaust port, the second oil separator, and the second valve. The exhaust then flows through the third valve and connects to the D port of the four-way valve. The first oil separator's bottom return port, the first capillary tube, and the second oil separator's bottom return port, the second capillary tube, are connected in parallel and return to the gas return port of the gas-liquid separator. The first compressor and the second compressor are connected to the outlets of the second heat exchanger and the third heat exchanger, respectively.

[0005] Preferably, the first compressor and the second compressor are both 25hp variable frequency scroll / piston / screw compressors, the first oil separator and the second oil separator are both vertical oil separators, the first valve, the second valve, the fifth valve and the thirteenth valve are all one-way valves, and the third valve and the fourteenth valve are all manual ball valves.

[0006] Preferably, the first heat exchanger is an air-cooled finned tube heat exchanger, and the fourth, seventh, eleventh, and twelfth valves are all electronic expansion valves, wherein the fourth and twelfth valves have a diameter of 5.5 mm, and the seventh and eleventh valves have a diameter of 2.2 mm.

[0007] Preferably, the second and third heat exchangers are both brazed plate heat exchangers, the sixth, eighth, ninth, tenth and sixteenth valves are all solenoid valves, the first filter is a copper filter with a diameter of 28.6 mm and a mesh size of 80; the second filter is a copper filter with a diameter of 15.88 mm and a mesh size of 60; and the balance tank is a vertical structure with an internal volume of 4 L.

[0008] Preferably, the fourth heat exchanger is a dry shell-and-tube heat exchanger / plate heat exchanger / coil-and-tube heat exchanger, the gas-liquid separator volume is ≥15L, the internal oil return hole diameter is 4mm, the fifteenth valve is a pressure relief valve with a pressure relief pressure ≥45bar, and the first capillary tube and the second capillary tube are both copper tubes with a diameter of 4mm, which are spirally wound and have a total length of 800mm.

[0009] Preferably, the four-way valve operates in a power-on heating mode and a power-off cooling mode. Under defrosting conditions, the sixteenth valve is energized and opens, and the twelfth valve is energized and fully open. The fourth, sixth, seventh, eighth, ninth, tenth, and eleventh valves are not energized. Furthermore, the sixteenth valve is energized only in defrosting mode. When only the first compressor is running in the system, the ninth, tenth, and eleventh valves are not energized. When only the second compressor is running in the system, the sixth, seventh, and eighth valves are not energized.

[0010] Preferably, in normal cooling and heating mode, the seventh valve and the eleventh valve are controlled by the compressor frequency. The seventh valve and the eleventh valve are allowed to be energized and opened only when the compressor operating frequency is ≥30HZ and lasts for 10 seconds.

[0011] Preferably, in the cooling mode, the fourth valve must not be electrically closed, and in the heating mode, the twelfth valve must not be electrically closed.

[0012] Preferably, when the compressor needs to be repaired, the third and fourteenth valves can be manually closed, requiring only the discharge of a portion of the refrigerant, thus saving on maintenance costs.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] By adopting a dual-frequency parallel compressor design, with each compressor having its own oil separator and economizer, precise oil return and efficient gas replenishment and enthalpy enhancement are ensured for each compressor to improve unit performance. The evaporator, condenser, and gas-liquid separator adopt a shared parallel system to ensure sufficient heat exchange of the refrigerant and uniform and stable gas intake. On the other hand, by setting different solenoid valves, firstly, the refrigerant is switched to flow through the economizer system of the corresponding compressor to ensure the system's adjustable range and the amount of refrigerant circulating; secondly, the economizer is bypassed during unit defrosting to reduce system pressure drop and ensure rapid defrosting. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the parallel high-efficiency variable frequency air conditioning system of this utility model;

[0016] Figure 2 This is a schematic diagram of the cooling mode structure of the parallel high-efficiency variable frequency air conditioning system of this utility model;

[0017] Figure 3 This is a schematic diagram of the heating mode structure of the parallel high-efficiency variable frequency air conditioning system of this utility model;

[0018] Figure 4 This is a schematic diagram of the defrosting mode structure of the parallel high-efficiency variable frequency air conditioning system of this utility model.

[0019] In the diagram: 1. First press; 2. Second press; 3. First oil separator; 4. Second oil separator; 5. First valve; 6. Second valve; 7. Third valve; 8. Four-way valve; 9. First heat exchanger; 10. Fourth valve; 11. Fifth valve; 12. Sixth valve; 13. First filter; 14. Second heat exchanger; 15. Seventh valve; 16. Third heat exchanger; 17. Eighth valve; 18. Ninth valve; 19. Tenth valve; 20. Eleventh valve; 21. Twelfth valve; 22. Thirteenth valve; 23. Second filter; 24. Balance tank; 25. Fourth heat exchanger; 26. Fourteenth valve; 27. Gas-liquid separator; 28. Fifteenth valve; 29. ​​First capillary tube; 30. Second capillary tube; 31. Sixteenth valve. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] This utility model embodiment provides a parallel ultra-low temperature inverter air conditioning unit system, the system flowchart of which is as follows: Figure 1 The aforementioned structure comprises a first press 1, a second press 2, a first oil separator 3, a second oil separator 4, a first valve 5, a second valve 6, a third valve 7, a four-way valve 8, a first heat exchanger 9, a fourth valve 10, a fifth valve 11, a sixth valve 12, a first filter 13, a second heat exchanger 14, a seventh valve 15, a third heat exchanger 16, an eighth valve 17, a ninth valve 18, a tenth valve 19, an eleventh valve 20, a twelfth valve 21, a thirteenth valve 22, a second filter 23, a balance tank 24, a fourth heat exchanger 25, a fourteenth valve 26, a gas-liquid separator 27, a fifteenth valve 28, a first capillary tube 29, a second capillary tube 30, and a sixteenth valve 31, all connected sequentially by copper pipes.

[0022] Figure 2This is a flowchart illustrating the cooling mode of a parallel high-efficiency variable frequency air conditioning system according to an embodiment of the present invention. In this mode, the four-way valve 8, the fourth valve 10, and the sixteenth valve 31 are all de-energized, and the C port of the four-way valve is tangential to the first heat exchanger 9. The main refrigerant flow is as follows: the high-temperature and high-pressure gaseous refrigerant discharged from the first compressor 1 flows sequentially through the first oil separator 3, and the high-temperature and high-pressure gaseous refrigerant discharged from the second compressor 2 flows sequentially through the second oil separator 4. The two refrigerant lines are connected in parallel and then merged, passing through the third valve 7 and the four-way valve 8 to enter the first heat exchanger 9 for condensation and heat dissipation. The gaseous refrigerant mixed with lubricating oil is also present in this flow. In the first oil separator 3 and the second oil separator 4, the lubricating oil returns from the bottom to the inlet of the gas-liquid separator 27 via copper pipes, the first capillary tube 29, and the second capillary tube 30. After entering the gas-liquid separator 27, the lubricating oil returns to the compressor's interior along with the compressor's suction gas for lubrication, ensuring normal oil return of the compressor. The main refrigerant, after being condensed and cooled in the first heat exchanger 9, becomes a medium-temperature, medium-pressure liquid refrigerant. Then, it passes through the fifth valve 11 and is divided into two main paths: the first main path flows through the sixth valve 12 and the first filter 13, and before entering the second heat exchanger 14, it bypasses an auxiliary refrigerant path that flows through the seventh valve. After valve 15, the refrigerant becomes a low-temperature, low-pressure gas-liquid two-phase refrigerant. The main refrigerant and auxiliary refrigerant exchange heat in the second heat exchanger 14. The main refrigerant releases heat for further subcooling to increase the unit's cooling capacity, while the auxiliary refrigerant absorbs heat and becomes superheated gaseous refrigerant, returning to the first compressor 1 to reduce the exhaust temperature. The second main refrigerant flows through the ninth valve 18 and enters the third heat exchanger 16. Before entering the third heat exchanger 16, an auxiliary refrigerant bypasses and flows through the eleventh valve 20, becoming a low-temperature, low-pressure gas-liquid two-phase refrigerant. The main refrigerant and auxiliary refrigerant exchange heat in the third heat exchanger 16. The main refrigerant releases heat... The hot refrigerant is further subcooled to increase the unit's cooling capacity. The auxiliary refrigerant absorbs heat and becomes superheated gaseous refrigerant, returning to the second compressor 2 to reduce the exhaust temperature. The first main refrigerant, after being subcooled, flows through the eighth valve 17, and the second main refrigerant, after being subcooled, flows through the tenth valve 19. Then, the two refrigerants are combined into one, entering the twelfth valve 21 for throttling, becoming a low-temperature, low-pressure two-phase refrigerant. This portion of the refrigerant then passes through the second filter 23 and enters the fourth heat exchanger 25 for evaporation and heat absorption to produce chilled water. Because the ambient temperature is generally high and the refrigerant pressure is high during refrigeration, it will not enter the balance tank 24. The main refrigerant absorbs heat in the fourth heat exchanger 25, becoming a low-temperature, low-pressure superheated gaseous refrigerant, and then flows sequentially through the four-way valve 8 and the fourteenth valve 26 back to the gas-liquid separator 27, completing the entire refrigeration cycle.

[0023] Because the system is adjustable, when a compressor needs to be shut down under low load: when only the first compressor 1 is running, valves 18 (ninth), 19 (tenth), and 20 (eleventh) should not be energized; when only the second compressor 2 is running, valves 12 (sixth), 15 (seventh), and 17 (eighth) should not be energized.

[0024] Figure 3 This is a flowchart of the heating mode of a parallel high-efficiency variable frequency air conditioning system according to an embodiment of the present invention. In this mode, the four-way valve 8 is energized to switch the refrigerant flow direction, so that the high-temperature and high-pressure gaseous refrigerant enters the fourth heat exchanger 25 to produce high-temperature hot water. In this mode, the twelfth valve 21 and the sixteenth valve 31 are not energized. The specific process is as follows: the high-temperature and high-pressure gaseous refrigerant discharged from the first compressor 1 flows through the first oil separator 3 in sequence, and the high-temperature and high-pressure gaseous refrigerant discharged from the second compressor 2 flows through the second oil separator 4 in sequence. The two refrigerants are connected in parallel and then merged and enter the fourth heat exchanger 25 through the third valve 7 and the four-way valve 8 for condensation and heat release to produce hot water. After condensation, the refrigerant becomes a medium-temperature and high-pressure liquid refrigerant. Since the ambient temperature is low during heating, the pressure in the balance tank 24 is low. At this time, some liquid refrigerant will enter the balance tank 24 under the action of pressure difference to balance the refrigerant quantity in the system and avoid the system exhaust temperature from being too high or tripping the high pressure. After condensation, the refrigerant in the main pipeline flows sequentially through the second filter 23 and the thirteenth valve 22, then splits into two paths. The first path flows through the eighth valve 17 into the downstream of the second heat exchanger 14, releasing heat and exiting from the upstream outlet of the heat exchanger. At the outlet, the liquid refrigerant bypasses to an auxiliary path, which is throttled by the seventh valve 15, becoming a low-temperature, low-pressure two-phase refrigerant. This absorbs heat from the medium-temperature, high-pressure refrigerant flowing through the second heat exchanger 14, becoming a low-temperature, low-pressure superheated gaseous refrigerant, which returns to the first compressor 1 to reduce the exhaust temperature. This is suitable for operating conditions with low ambient temperatures in extremely cold weather. Similarly, the second refrigerant branching from the main pipeline flows through the tenth valve 19 into the downstream of the third heat exchanger 16, releasing heat and exiting from the upstream outlet of the heat exchanger. The refrigerant bypass at the outlet flows out through an auxiliary path, which is throttled by the eleventh valve 20 and becomes a low-temperature, low-pressure two-phase refrigerant. It absorbs the heat from the medium-temperature, high-pressure refrigerant flowing through the third heat exchanger 16 and becomes a low-temperature, low-pressure superheated gaseous refrigerant. It then returns to the second compressor 2 to reduce the exhaust temperature, thus making it suitable for operating conditions with low ambient temperature in extremely cold weather. The two refrigerant streams flow out from the sixth valve 12 and the ninth valve 18 respectively and then merge into one stream. It then enters the fourth valve 10 for throttling and pressure reduction, becoming a low-temperature, low-pressure two-phase refrigerant. It then enters the first heat exchanger 9 for evaporation and heat absorption, becoming a low-temperature, low-pressure superheated refrigerant. Finally, it flows through the four-way valve 8 back to the gas-liquid separator 27 to complete the entire heating cycle.

[0025] Figure 4This is a flow chart of a parallel high-efficiency variable frequency air conditioning system defrosting mode according to an embodiment of the present invention. In this mode, to avoid liquid carryover in the compressor suction and to avoid a large pressure drop in the refrigerant flow economizer that would affect the defrosting effect, all economizer systems are bypassed. That is, valves 18, 19, 20, 12, 15, and 17 are not energized; valve 31 is energized and opened. Apart from this, the specific refrigerant flow is the same as in the cooling mode. The difference is that after the high-temperature and high-pressure gaseous refrigerant releases heat in the first heat exchanger 9 to melt the frost layer, the refrigerant becomes a two-phase gas-liquid refrigerant. Then, it flows sequentially through valve 11, valve 21, and filter 23 into the fourth heat exchanger 25 for system heating before defrosting. At this time, the water temperature in the fourth heat exchanger 25 is high, and the two-phase refrigerant will quickly evaporate and absorb heat to become a low-temperature and low-pressure superheated gaseous refrigerant. Then, it flows sequentially through the four-way valve 8 back to the gas-liquid separator 27 to complete the entire defrosting cycle.

[0026] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A parallel super-low temperature variable frequency air conditioning unit system, characterized in that: The first compressor (1), the second compressor (2), the first oil separator (3), the second oil separator (4), the first valve (5), the second valve (6), the third valve (7), the four-way valve (8), the first heat exchanger (9), the fourth valve (10), the fifth valve (11), the sixth valve (12), the first filter (13), the second heat exchanger (14), the seventh valve (15), the third heat exchanger (16), the eighth valve (17), the ninth valve (18), the tenth valve (19), the eleventh valve (20), the twelfth valve (21), the thirteenth valve (22), the second filter (23), the balance tank (24), the fourth heat exchanger (25), the fourteenth valve (26), the gas-liquid separator (27), the fifteenth valve (28), the first capillary (29), the second capillary (30) and the sixteenth valve (31) are sequentially connected by copper pipelines, the exhaust management system of the first compressor (1) composed of the first compressor exhaust port-the first oil separator (3)-the first valve (5) is connected in parallel with the exhaust management system of the second compressor (2) composed of the second compressor exhaust port-the second oil separator (4)-the second valve (6), then flows through the third valve (7) and is connected with the D port of the four-way valve (8); the bottom oil return port of the first oil separator (3)-the first capillary (29) and the bottom oil return port of the second oil separator (4)-the second capillary (30) are connected in parallel and then return to the gas return port of the gas-liquid separator (27); the first compressor and the second compressor are respectively connected with the gas outlet of the second heat exchanger (14) and the third heat exchanger (16).

2. The parallel super-low-temperature variable frequency air conditioning unit system according to claim 1, characterized in that: The first compressor and the second compressor are both 25hp variable frequency scroll / piston / screw compressors, the first oil separator (3) and the second oil separator (4) are both vertical oil separators, the first valve (5), the second valve (6), the fifth valve (11) and the thirteenth valve (22) are all one-way valves, and the third valve (7) and the fourteenth valve (26) are both manual ball valves.

3. The parallel super-low-temperature variable frequency air conditioning unit system according to claim 1, characterized in that: The first heat exchanger (9) is a wind-cooled finned tube heat exchanger, the fourth valve (10), the seventh valve (15), the eleventh valve (20) and the twelfth valve (21) are all electronic expansion valves, wherein the fourth valve (10) and the twelfth valve (21) have a diameter of 5.5mm, and the seventh valve (15) and the eleventh valve (20) have a diameter of 2.2mm.

4. The parallel super-low-temperature variable frequency air conditioning unit system according to claim 1, characterized in that: The second heat exchanger (14) and the third heat exchanger (16) are both brazed plate heat exchangers, the sixth valve (12), the eighth valve (17), the ninth valve (18), the tenth valve (19) and the sixteenth valve (31) are all solenoid valves, the first filter (13) is a copper filter with a cylinder diameter of 28.6mm and a mesh number of 80 meshes, the second filter (23) is a copper filter with a cylinder diameter of 15.88 and a mesh number of 60 meshes, and the balance tank (24) is a vertical structure with a content volume of 4L.

5. The parallel super-low-temperature variable frequency air conditioning unit system according to claim 1, characterized in that: The fourth heat exchanger (25) is a dry shell and tube heat exchanger / plate heat exchanger / sleeve heat exchanger, the gas-liquid separator (27) has a volume of ≥15L, the internal oil return hole diameter is 4mm, the fifteenth valve (28) is a pressure relief valve, the pressure relief pressure is ≥45bar, the first capillary (29) and the second capillary (30) are both copper pipes with a diameter of 4mm, in a threaded winding shape, and the total length is 800mm.

6. The parallel super-low-temperature variable frequency air conditioning unit system according to claim 1, characterized in that: The four-way valve (8) is in the electric heating and power-off refrigeration mode, under the defrosting condition, the sixteenth valve (31) is powered on, and the twelfth valve (21) is powered on in the full step; the fourth valve (10), the sixth valve (12), the seventh valve (15), the eighth valve (17), the ninth valve (18), the tenth valve (19) and the eleventh valve (20) are all not powered on; and the sixteenth valve (31) is powered on only in the defrosting mode, when the system only the first compressor operates, the ninth valve (18), the tenth valve (19) and the eleventh valve (20) are all not powered on, when the system only the second compressor operates, the sixth valve (12), the seventh valve (15) and the eighth valve (17) are all not powered on.

7. The parallel super-low-temperature variable frequency air conditioning unit system according to claim 1, characterized in that: In the normal refrigeration and heating mode, the seventh valve (15) and the eleventh valve (20) are controlled by the compressor frequency, when the compressor operating frequency is ≥30HZ and lasts for 10s, the seventh valve (15) and the eleventh valve (20) are allowed to be powered on. 8.The parallel super-low-temperature variable frequency air conditioning unit system according to claim 1, wherein: In the refrigeration mode, the fourth valve (10) is not powered off, and in the heating mode, the twelfth valve (21) is not powered off. 9.The parallel super-low-temperature variable frequency air conditioning unit system according to claim 1, wherein: When the compressor needs to be repaired, the third valve (7) and the fourteenth valve (26) can be manually related, only part of the refrigerant needs to be discharged, and the maintenance cost is saved.

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