Falling film air-cooled screw heat pump unit system

Abstract

The utility model relates to a falling film air-cooled screw heat pump unit system. Including: high -efficient falling film evaporimeter, V type heat exchanger group, four -way reversing valve, refrigerating liquid flow direction control passageway, screw compressor, the V type heat exchanger group includes many V type heat exchangers, and the liquid collecting pipe mouth of each V type heat exchanger is connected with one end of thermal expansion valve, the high -efficient falling film evaporimeter connects four -way reversing valve, the high -efficient falling film evaporimeter is connected to refrigerating liquid flow direction control passageway, and refrigerating liquid flow direction control passageway connects thermal expansion valve, four -way reversing valve connects all V type heat exchangers, and four -way reversing valve connects screw compressor, the utility model can solve the problem that the heat exchange efficiency is limited, the refrigerant filling amount is big, the oil return is difficult and the heating attenuation and defrosting performance are not good under low temperature environment etc. of traditional air-cooled screw heat pump unit because of adopting full -liquid type or dry type evaporimeter.

Description

Technical Field

[0001] This utility model belongs to the field of heat pump technology, and in particular relates to a falling film type air-cooled screw heat pump unit system. Background Technology

[0002] Air-cooled screw heat pump units, as integrated central air conditioning equipment that combines cooling and heating functions, are widely used in various commercial complexes, office buildings, and industrial plants due to their ease of installation and wide applicability, eliminating the need for cooling towers and boilers. Among them, units using screw compressors have become one of the mainstream choices in the market due to their compact structure, stable operation, long service life, and wide capacity adjustment range.

[0003] Currently, most air-cooled screw heat pump units on the market use either flooded or dry evaporators for their water-side heat exchangers (evaporators). Flooded evaporators have a higher heat transfer coefficient, but they suffer from problems such as large refrigerant charge and difficulty in oil return; dry evaporators have a smaller charge, but they suffer from lower heat transfer efficiency and uneven refrigerant distribution.

[0004] However, existing air-cooled screw heat pump units still have many shortcomings that urgently need to be addressed. First, their water-side heat exchangers face a dilemma in selection. Second, during winter heating operation, the air-side heat exchanger is prone to frosting, requiring frequent defrosting, which not only increases energy consumption but also disrupts the continuity of indoor heating. Furthermore, maintaining the unit's high efficiency under a wide range of operating conditions and partial loads is a common challenge currently facing the technology.

[0005] Therefore, there is an urgent need to develop a new type of air-cooled screw heat pump unit that can significantly improve heat exchange efficiency and operational stability while reducing refrigerant charge, and effectively address the frosting problem, thereby achieving high-efficiency and energy-saving operation under all operating conditions. Summary of the Invention

[0006] This utility model provides a falling film air-cooled screw heat pump unit system to solve the problems of limited heat exchange efficiency, large refrigerant charge, difficult oil return, and poor heating and defrosting performance in low-temperature environments that exist in traditional air-cooled screw heat pump units due to the use of flooded or dry evaporators.

[0007] The technical solution of this utility model is as follows: a falling film air-cooled screw heat pump unit system, including: a high-efficiency falling film evaporator, a V-type heat exchanger group, a four-way reversing valve, a refrigerant flow control passage, and a screw compressor; The V-type heat exchanger group includes multiple V-type heat exchangers. The liquid collection port of each V-type heat exchanger is connected to one end of a thermal expansion valve. The two ends of the thermal expansion valve are connected in parallel with a capillary tube and a first one-way valve. The inlet end of the first one-way valve is connected to one end of the thermal expansion valve, and the outlet end of the first one-way valve is connected to the other end of the thermal expansion valve. The gas inlet and outlet of the high-efficiency falling film evaporator are connected to the first port of the four-way reversing valve, the refrigerant inlet and refrigerant outlet of the high-efficiency falling film evaporator are connected to one end of the refrigerant flow control passage, and the other end of the refrigerant flow control passage is connected to the other end of the thermal expansion valve. The second port of the four-way reversing valve is connected to the straight pipe port of all the V-type heat exchangers, the fourth port of the four-way reversing valve is connected to the exhaust port of the screw compressor, and the suction port of the screw compressor is connected to the third port of the four-way reversing valve.

[0008] Furthermore, an oil separator is provided between the exhaust port of the screw compressor and the fourth port of the four-way reversing valve. The inlet of the oil separator is connected to the exhaust port of the screw compressor, the return oil outlet of the oil separator is connected to the suction port of the screw compressor, and the gas outlet of the oil separator is connected to the fourth port of the four-way reversing valve.

[0009] Furthermore, a gas-liquid separator is provided between the suction port of the screw compressor and the third port of the four-way reversing valve. The inlet of the gas-liquid separator is connected to the third port of the four-way reversing valve, and the outlet of the gas-liquid separator is connected to the suction port of the screw compressor.

[0010] Furthermore, it also includes an ejector pump, the power source inlet of which is connected to the oil return outlet of the oil separator through a first solenoid valve, the suction port of the ejector pump is connected to the oil suction port of the high-efficiency falling film evaporator through a second solenoid valve, and the outlet of the ejector pump is connected to the suction port of the screw compressor.

[0011] Furthermore, the refrigerant flow control passage includes: a second check valve, a third check valve, an electronic expansion valve, a fourth expansion valve, a fifth check valve, and a sixth check valve; The inlet end of the third one-way valve is connected to the other end of the thermal expansion valve and the outlet end of the second one-way valve. The outlet end of the third one-way valve is connected to one end of the electronic expansion valve, the outlet end of the fourth expansion valve, and the inlet end of the second one-way valve. The inlet end of the fourth expansion valve is connected to the other end of the electronic expansion valve, the inlet end of the fifth one-way valve, and the outlet end of the sixth one-way valve. The outlet end of the fifth one-way valve is connected to the liquid inlet of the high-efficiency falling film evaporator. The inlet end of the sixth one-way valve is connected to the liquid outlet of the high-efficiency falling film evaporator.

[0012] Furthermore, a liquid storage tank and a drying filter are sequentially connected between the outlet end of the third one-way valve and one end of the electronic expansion valve.

[0013] The beneficial effects of this utility model are as follows: 1. This utility model adopts a high-efficiency falling film evaporator. The falling film technology uses a spray device to make the refrigerant uniformly form a liquid film on the surface of the high-efficiency heat exchange tube, realizing film evaporation. Compared with traditional flooded or dry evaporators, this method has higher heat exchange efficiency, can effectively reduce the amount of refrigerant charged, and at the same time, the liquid level is stable, ensuring better oil return performance of the unit.

[0014] 2. The heat exchanger of this utility model (acting as a condenser during cooling and an evaporator during heating) adopts a multi-V-shaped structural layout. This design increases the heat exchange area, improves airflow organization, reduces air resistance, and enables more uniform frosting (during heating), thus helping to improve heat exchange efficiency and defrosting effect.

[0015] 3. In this utility model, each V-type heat exchanger has three parallel branches on its refrigerant pipeline: a thermostatic expansion valve on the first branch, a capillary tube on the second branch, and a one-way valve on the third branch. This structure allows the unit to automatically select the optimal throttling path in different modes: during cooling, the refrigerant flows smoothly through the one-way valve; during heating, the flow rate is precisely adjusted according to the superheat of each unit by the thermostatic expansion valve and the capillary tube; during defrosting, the refrigerant circulates through the one-way valve.

[0016] 4. This utility model includes an ejector pump oil return system. The power source inlet of the ejector pump is connected to the oil return outlet of the oil separator via a pipeline and a first solenoid valve to obtain high-pressure oil as power. Its suction inlet is connected to a high-efficiency falling film evaporator via a pipeline and a second solenoid valve to draw in the accumulated oil-liquid mixture. Its outlet is connected to the suction pipe of the screw compressor. This design achieves active and efficient recovery of oil accumulated in the high-efficiency falling film evaporator. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. The described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0019] In the technical solution of this utility model, Figure 1 This is a structural diagram illustrating the specific structure of a falling film air-cooled screw heat pump unit system according to this utility model, as shown below. Figure 1 As shown, this utility model includes: 2. High-efficiency falling film evaporator, 12. V-type heat exchanger group, 6. Four-way reversing valve, refrigerant flow control passage, 1. Screw compressor; The V-type heat exchanger group 12 includes multiple V-type heat exchangers 12-1. The liquid collection port of each V-type heat exchanger 12-1 is connected to one end of a thermal expansion valve 8. The two ends of the thermal expansion valve 8 are connected in parallel to a capillary tube 10 and a first one-way valve 9-1. The inlet end of the first one-way valve 9-1 is connected to one end of the thermal expansion valve 8, and the outlet end of the first one-way valve 9-1 is connected to the other end of the thermal expansion valve 8. The gas inlet and outlet of the high-efficiency falling film evaporator 2 are connected to the first port of the four-way reversing valve 6. The refrigerant inlet and refrigerant outlet of the high-efficiency falling film evaporator 2 are connected to one end of the refrigerant flow control passage, and the other end of the refrigerant flow control passage is connected to the other end of the thermal expansion valve 8. The second port of the four-way reversing valve 6 is connected to the straight pipe port of all the V-type heat exchangers 12-1, the fourth port of the four-way reversing valve 6 is connected to the exhaust port of the screw compressor 1, and the intake port of the screw compressor 1 is connected to the third port of the four-way reversing valve 6.

[0020] In one embodiment of this utility model, an oil separator 3 is provided between the exhaust port of the screw compressor 1 and the fourth port of the four-way reversing valve 6. The inlet of the oil separator 3 is connected to the exhaust port of the screw compressor 1, the oil return outlet of the oil separator 3 is connected to the suction port of the screw compressor 1, and the gas outlet of the oil separator 3 is connected to the fourth port of the four-way reversing valve 6.

[0021] In one embodiment of this utility model, a gas-liquid separator 4 is provided between the suction port of the screw compressor 1 and the third port of the four-way reversing valve 6. The inlet of the gas-liquid separator 4 is connected to the third port of the four-way reversing valve 6, and the outlet of the gas-liquid separator 4 is connected to the suction port of the screw compressor 1.

[0022] In one embodiment of the present invention, an ejector pump 14 is also included. The power source inlet of the ejector pump 14 is connected to the oil return outlet of the oil separator 3 through a first solenoid valve 13-1. The suction port of the ejector pump 14 is connected to the oil suction port of the high-efficiency falling film evaporator 2 through a second solenoid valve 13-2. The outlet of the ejector pump 14 is connected to the air suction port of the screw compressor 1.

[0023] In one embodiment of this utility model, the refrigerant flow control passage includes: a second one-way valve 9-2, a third one-way valve 9-3, an electronic expansion valve 7, a fourth expansion valve 9-4, a fifth one-way valve 9-5, and a sixth one-way valve 9-6; The inlet end of the third one-way valve 9-3 is connected to the other end of the thermal expansion valve 8 and the outlet end of the second one-way valve 9-2. The outlet end of the third one-way valve 9-3 is connected to one end of the electronic expansion valve 7, the outlet end of the fourth expansion valve 9-4, and the inlet end of the second one-way valve 9-2. The inlet end of the fourth expansion valve 9-4 is connected to the other end of the electronic expansion valve 7, the inlet end of the fifth one-way valve 9-5, and the outlet end of the sixth one-way valve 9-6. The outlet end of the fifth one-way valve 9-5 is connected to the liquid inlet of the high-efficiency falling film evaporator 2. The inlet end of the sixth one-way valve 9-6 is connected to the liquid outlet of the high-efficiency falling film evaporator 2.

[0024] In one embodiment of this utility model, a liquid storage tank 5 and a drying filter 11 are sequentially connected between the outlet end of the third one-way valve 9-3 and one end of the electronic expansion valve 7.

[0025] This invention equips each V-type heat exchanger 12-1 with an independent thermal expansion valve 8. In heating mode, the superheat of each V-type heat exchanger 12-1 is monitored. Based on the superheat of each V-type heat exchanger 12-1, the opening of its corresponding thermal expansion valve 8 is independently adjusted to match the refrigerant flow rate with the actual heat exchange requirements of the V-type heat exchanger 12-1. The superheat is adapted according to the oncoming wind speed or frosting conditions. For V-type heat exchangers 12-1 with high wind speed and strong heat exchange, their thermal expansion valve 8 is opened wider to supply more refrigerant. For V-type heat exchangers 12-1 with low wind speed and weak heat exchange, their thermal expansion valve 8 is closed to prevent incomplete refrigerant evaporation.

[0026] This invention monitors the outlet temperature or pressure parameters of each V-type heat exchanger 12-1 and determines the degree of frost based on the parameters.

[0027] Based on the assessment of the degree of frost formation, the opening of the thermal expansion valve 8 corresponding to the severely frost-covered V-type heat exchanger 12-1 is independently controlled to achieve precise defrosting flow control.

[0028] Controlling the four-way reversing valve 6 to switch the system from heating mode to refrigeration cycle, and using the high-temperature refrigerant discharged from the screw compressor 1 to defrost the frosted air-side heat exchanger 12.

[0029] The refrigerant completes the defrosting cycle by flowing through the bypass throttling path formed by the one-way valve 9-1.

[0030] This invention can control multiple V-type heat exchangers 12-1 to defrost simultaneously, achieving rapid defrosting.

[0031] This utility model provides an ejector pump 14, whose power source inlet is connected to the oil return outlet of the oil separator 3, whose suction inlet is connected to the falling film evaporator 2, and whose outlet is connected to the suction pipe of the screw compressor 1.

[0032] Open the solenoid valves 13 on the power source line and the oil suction line, and use the high-pressure oil drawn from the oil return port of the oil separator 3 as the power source to pump the mixture of oil and refrigerant accumulated at the bottom of the falling film evaporator 2 back to the screw compressor 1 via the ejector pump 14. The following are specific implementations of this utility model: During refrigeration, the four-way reversing valve 6 is de-energized. The high-temperature, high-pressure refrigerant and lubricating oil mixture discharged from the screw compressor 1 first enters the oil separator 3. The oil separator 3 separates most of the lubricating oil from the refrigerant gas by reducing the flow rate, changing the flow direction, impacting the baffle, or filtering through the filter element. The high-temperature, high-pressure refrigerant gas then enters the air-side heat exchanger 12 via the four-way reversing valve 6, where it acts as a condenser. The air driven by the fan carries away the heat, and the refrigerant condenses into a high-pressure liquid. The high-pressure liquid refrigerant then flows through the one-way valve 9-1, one-way valve 9-3, the dryer filter 11, and the liquid receiver 5 before flowing to the electronic expansion valve 7. The electronic expansion valve 7 throttles and reduces the pressure, turning it into a low-temperature, low-pressure gas-liquid two-phase mixture. The low-temperature, low-pressure refrigerant then enters the falling film evaporator 2 via the one-way valve 9-5, where it acts as an evaporator, absorbing heat from the circulating water outside the heat exchange tubes and evaporating, thus providing chilled water to the user. The evaporated low-temperature, low-pressure refrigerant gas passes through the four-way reversing valve 6 to the gas-liquid separator 4. The dried low-temperature, low-pressure refrigerant gas in the gas-liquid separator 4 returns to the suction port of the screw compressor 1, completing the refrigeration cycle.

[0033] When heating, the four-way reversing valve 6 is energized to switch the flow direction. The high-temperature, high-pressure refrigerant and lubricating oil mixture discharged from the screw compressor 1 first enters the oil separator 3. The oil separator 3 separates most of the lubricating oil from the refrigerant gas by reducing the flow rate, changing the flow direction, impacting the baffle, or filtering through the filter element. The high-temperature, high-pressure refrigerant gas then enters the high-efficiency falling film evaporator 2 via the four-way reversing valve 6, where it acts as a condenser, releasing heat to the circulating water in the pipes to produce hot water. The high-pressure liquid refrigerant, after condensation in the falling film evaporator 2, flows to the electronic expansion valve 7 for throttling and pressure reduction after passing through the one-way valve 9-6. The low-temperature, low-pressure refrigerant then enters the air-side heat exchanger 12 via the one-way valve 9-2 and the thermostatic expansion valve 8, where it acts as an evaporator, absorbing heat from the outdoor air and evaporating. The evaporated refrigerant gas passes through the four-way reversing valve 6 to the gas-liquid separator 4. The dried, low-temperature, low-pressure refrigerant gas from the gas-liquid separator 4 returns to the suction port of the screw compressor 1, completing the heating cycle.

[0034] Considering that each V-type heat exchanger 12-1 is installed in different parts of the unit, its oncoming air velocity, air temperature, and frosting conditions differ. The middle V-type heat exchanger 12-1 has a high air velocity and good heat exchange; the V-type heat exchangers 12-1 on both sides have low air velocity and are prone to frosting. Therefore, each V-type heat exchanger 12-1 is equipped with an independent thermal expansion valve 8 to ensure that each V-type heat exchanger 12-1 receives a refrigerant flow rate precisely matched to its actual heat exchange requirements. For V-type heat exchangers 12-1 with high air velocity and strong heat exchange, the superheat increases, and the thermal expansion valve 8 opens wider to supply more refrigerant; for V-type heat exchangers 12-1 with low air velocity and weak heat exchange, the thermal expansion valve 8 closes less to prevent incomplete refrigerant evaporation. Simultaneously, for defrosting, in heating mode, the control system can monitor the temperature / pressure at the outlet of each V-type heat exchanger 12-1 to determine its degree of frosting. For units with severe frosting, more precise flow control can be implemented during defrosting. Reduce the impact on overall heating capacity.

[0035] During defrosting, the system briefly switches from "heating mode" to "cooling mode," utilizing the high-temperature refrigerant discharged from the screw compressor 1 to melt the frost layer on the evaporator of the air-side heat exchanger 12. The four-way reversing valve 6 switches to cooling mode, reducing the load on the screw compressor 1. The mixture of high-temperature, high-pressure refrigerant and lubricating oil discharged from the screw compressor 1 first enters the oil separator 3. The oil separator 3 separates most of the lubricating oil from the refrigerant gas by reducing flow rate, changing flow direction, impacting baffles, or filtering through a filter element. The high-temperature, high-pressure refrigerant gas then enters the air-side heat exchanger 12 via the four-way reversing valve 6, acting as a condenser. The refrigerant condenses and releases heat inside the pipes; the enormous latent and sensible heat quickly melts the frost layer on the fin surface into water, which falls down. The defrosting water is discharged from the drain trough. The condensed high-pressure liquid refrigerant then passes through a specific throttling path, capillary tube 10, and one-way valve 9-1. After passing through one-way valve 9-3, dryer filter 11, and receiver 5, it flows to the electronic expansion valve 7. The electronic expansion valve 7 throttles and reduces the pressure, turning the refrigerant into a low-temperature, low-pressure gas-liquid two-phase mixture. The low-temperature, low-pressure refrigerant enters the high-efficiency falling film evaporator 2 through the one-way valve 9-5, where it acts as an evaporator. The evaporated low-temperature, low-pressure refrigerant gas passes through the four-way reversing valve 6 to the gas-liquid separator 4. The dried low-temperature, low-pressure refrigerant gas, after passing through the gas-liquid separator 4, returns to the suction port of the screw compressor 1, completing the defrosting cycle.

[0036] In this invention, during oil return, the oil separator 3 returns oil. The mixture of high-temperature, high-pressure refrigerant and lubricating oil discharged from the screw compressor 1 first enters the oil separator 3. The oil separator 3 returns most of the separated lubricating oil to the suction port of the screw compressor 1 via auxiliary components. The ejector pump 14 also returns oil. The power source inlet of the ejector pump 14 is connected to the oil return outlet of the oil separator 3 via a pipeline and a first solenoid valve 13-1 to obtain high-pressure oil as power. Its suction port is connected to the high-efficiency falling film evaporator 2 via a pipeline and a second solenoid valve 13-2 to draw in the accumulated oil mixture. Its outlet is connected to the suction pipe of the screw compressor 1. This design achieves active and efficient recovery of oil accumulated in the falling film evaporator. It overcomes the shortcomings of traditional oil return methods under low load, ensures the lubrication safety of the compressor under any operating condition, and extends the unit's lifespan.

[0037] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although this utility model has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications and substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A falling film air-cooled screw heat pump unit system, characterized in that it includes: High-efficiency falling film evaporator (2), V-type heat exchanger group (12), four-way reversing valve (6), refrigerant flow control passage, screw compressor (1). The V-type heat exchanger group (12) includes multiple V-type heat exchangers (12-1). The liquid collection port of each V-type heat exchanger (12-1) is connected to one end of a thermal expansion valve (8). The two ends of the thermal expansion valve (8) are connected in parallel to a capillary tube (10) and a first one-way valve (9-1). The inlet end of the first one-way valve (9-1) is connected to one end of the thermal expansion valve (8), and the outlet end of the first one-way valve (9-1) is connected to the other end of the thermal expansion valve (8). The gas inlet and outlet of the high-efficiency falling film evaporator (2) are connected to the first port of the four-way reversing valve (6), the refrigerant inlet and refrigerant outlet of the high-efficiency falling film evaporator (2) are connected to one end of the refrigerant flow control passage, and the other end of the refrigerant flow control passage is connected to the other end of the thermal expansion valve (8). The second port of the four-way reversing valve (6) is connected to the straight port of all the V-type heat exchangers (12-1), the fourth port of the four-way reversing valve (6) is connected to the exhaust port of the screw compressor (1), and the intake port of the screw compressor (1) is connected to the third port of the four-way reversing valve (6).

2. The falling film air-cooled screw heat pump unit system as described in claim 1, characterized in that, An oil separator (3) is provided between the exhaust port of the screw compressor (1) and the fourth port of the four-way reversing valve (6). The inlet of the oil separator (3) is connected to the exhaust port of the screw compressor (1), the oil return outlet of the oil separator (3) is connected to the suction port of the screw compressor (1), and the gas outlet of the oil separator (3) is connected to the fourth port of the four-way reversing valve (6).

3. The falling film air-cooled screw heat pump unit system as described in claim 2, characterized in that, A gas-liquid separator (4) is provided between the suction port of the screw compressor (1) and the third port of the four-way reversing valve (6). The inlet of the gas-liquid separator (4) is connected to the third port of the four-way reversing valve (6), and the outlet of the gas-liquid separator (4) is connected to the suction port of the screw compressor (1).

4. The falling film air-cooled screw heat pump unit system as described in claim 3, characterized in that, It also includes an ejector pump (14), the power source inlet of which is connected to the oil return outlet of the oil separator (3) through a first solenoid valve (13-1), the suction port of the ejector pump (14) is connected to the oil suction port of the high-efficiency falling film evaporator (2) through a second solenoid valve (13-2), and the outlet of the ejector pump (14) is connected to the air suction port of the screw compressor (1).

5. The falling film air-cooled screw heat pump unit system as described in claim 1, characterized in that, The refrigerant flow control passage includes: a second check valve (9-2), a third check valve (9-3), an electronic expansion valve (7), a fourth expansion valve (9-4), a fifth check valve (9-5), and a sixth check valve (9-6). The inlet end of the third one-way valve (9-3) is connected to the other end of the thermal expansion valve (8) and the outlet end of the second one-way valve (9-2). The outlet end of the third one-way valve (9-3) is connected to one end of the electronic expansion valve (7), the outlet end of the fourth expansion valve (9-4), and the inlet end of the second one-way valve (9-2). The inlet end of the fourth expansion valve (9-4) is connected to the other end of the electronic expansion valve (7), the inlet end of the fifth one-way valve (9-5), and the outlet end of the sixth one-way valve (9-6). The outlet end of the fifth one-way valve (9-5) is connected to the liquid inlet of the high-efficiency falling film evaporator (2). The inlet end of the sixth one-way valve (9-6) is connected to the liquid outlet of the high-efficiency falling film evaporator (2).

6. The falling film air-cooled screw heat pump unit system as described in claim 5, characterized in that, The outlet end of the third check valve (9-3) is connected in sequence to one end of the electronic expansion valve (7) by a liquid storage tank (5) and a dryer filter (11).

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