Low-temperature air source heat pump system

Abstract

The utility model discloses a low-temperature air source heat pump system which comprises a compressor, a liquid storage device, an air side heat exchanger, a water side heat exchanger, a four-way valve, an indoor unit electronic expansion valve and an outdoor unit electronic expansion valve. The four-way valve is connected with a refrigerant input air pipe of the liquid storage device, the air side heat exchanger, the water side heat exchanger and the exhaust side of the compressor, the air side heat exchanger is connected with the outdoor unit electronic expansion valve, the outdoor unit electronic expansion valve is connected with a refrigerant discharge liquid pipe of the liquid storage device, and the water side heat exchanger is connected with the indoor unit electronic expansion valve. The indoor unit electronic expansion valve is connected with a refrigerant input liquid pipe of the liquid storage device. The migration of the refrigerant to the low-pressure side when the external environment temperature is low and the unit is standby is reduced, the liquid return amount of the system during starting and defrosting is reduced, the liquid refrigerant in the low-pressure cavity of the liquid storage device during heating operation is reduced, the supercooling degree and the evaporation temperature of the system are increased, and the heating operation energy efficiency ratio is increased.

Description

Technical Field

[0001] The utility model belongs to the technical field of air conditioners, and particularly relates to a low-temperature air source heat pump system. Background Art

[0002] For the low ambient temperature air source heat pump units on the current market, when the unit is in the standby state and the outdoor ambient temperature is relatively low, the temperature of the water-side heat exchanger is high, and the temperature of the air-side heat exchanger is low. The refrigerant migrates from the high-pressure side to the low-pressure side through the gas pipe and is cooled on the low-pressure side. At this time, when the unit starts, a liquid return phenomenon occurs, increasing the risk of liquid slugging of the compressor; during heating operation at a low external ambient temperature, the liquid supply amount on the evaporation side is adjusted by an electronic expansion valve. The adjustment of the electronic expansion valve has hysteresis, which will cause too much refrigerant to accumulate in the low-pressure accumulator, resulting in insufficient refrigerant circulation in the system and a high system exhaust temperature, leading to failures; at the initial stage of defrosting operation, the four-way valve switches, causing the evaporator and condenser of the system to be interchanged. At this time, there is a large amount of liquid refrigerant in the evaporator that cannot evaporate, and the system has liquid return, increasing the risk of liquid slugging of the compressor; when the external ambient temperature is relatively low, the air heat capacity is small, and it is difficult to absorb heat, resulting in a low heating coefficient of performance. Summary of the Utility Model

[0003] The utility model provides a low-temperature air source heat pump system, which solves the problems of liquid return phenomenon of the unit in the existing low-temperature air source heat pump system under low-temperature environment and standby state, insufficient refrigerant circulation during heating operation in low-temperature environment, high system exhaust temperature, and resulting in failures.

[0004] To achieve the above object, the utility model provides the following technical solution: A low-temperature air source heat pump system includes a compressor, a liquid storage device, an air-side heat exchanger, a water-side heat exchanger, a four-way valve, an indoor electronic expansion valve, and an outdoor electronic expansion valve. The suction side of the compressor is connected to the refrigerant discharge gas pipe of the liquid storage device. The four-way valve is connected to the refrigerant input gas pipe of the liquid storage device, the air-side heat exchanger, the water-side heat exchanger, and the exhaust side of the compressor. The air-side heat exchanger is connected to the outdoor electronic expansion valve, and the outdoor electronic expansion valve is connected to the refrigerant discharge liquid pipe of the liquid storage device. The water-side heat exchanger is connected to the indoor electronic expansion valve, and the indoor electronic expansion valve is connected to the refrigerant input liquid pipe of the liquid storage device.

[0005] Preferably, the liquid storage device consists of an outer shell and an inner shell, forming two inner and outer cavities. The outer cavity is a high-pressure cavity with a pressure range of 1.6 - 4.4 MPa, and the inner cavity is a low-pressure cavity with a pressure range of 0.05 - 1.5 MPa.

[0006] Preferably, the high-pressure cavity is composed of an inner shell and an outer shell, and the low-pressure cavity is formed by the inner shell alone.

[0007] Preferably, the bottom height difference between the high-pressure cavity and the low-pressure cavity is greater than 35 mm.

[0008] Preferably, the refrigerant inlet pipe and the refrigerant discharge pipe are inserted into the low-pressure cavity and fixedly connected to the top of the high-pressure cavity.

[0009] Preferably, the refrigerant inlet liquid pipe and the refrigerant outlet liquid pipe are respectively fixedly connected to the bottom of the high-pressure cavity.

[0010] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0011] When the outdoor ambient temperature is low and the unit is on standby, the refrigerant exchanges heat through the high-pressure cavity and the low-pressure cavity of the liquid receiver, reducing the temperature of the refrigerant on the high-pressure side and increasing the temperature of the refrigerant on the low-pressure side, so that as much refrigerant as possible is stored on the high-pressure side while reducing the migration of the refrigerant to the low-pressure side;

[0012] When the outdoor ambient temperature is low and the system starts up and defrosts, the refrigerant exchanges heat through the high-pressure cavity and the low-pressure cavity of the liquid receiver, reducing the liquid return volume of the system and reducing the risk of liquid slugging of the compressor;

[0013] When the outdoor ambient temperature is low and the system is in heating operation, the refrigerant exchanges heat through the high-pressure cavity and the low-pressure cavity of the liquid receiver, reducing the liquid accumulation in the low-pressure cavity and ensuring the refrigerant circulation volume of the system; increasing the system subcooling degree and evaporation temperature, and improving the energy efficiency ratio of the heating operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a structural diagram of the low-temperature air source heat pump system of the present utility model;

[0015] Figure 2 is a schematic structural diagram of the liquid receiver of the low-temperature air source heat pump system of the present utility model;

[0016] In the figure: compressor 1, liquid receiver 2, air-side heat exchanger 3, water-side heat exchanger 4, four-way valve 5, indoor electronic expansion valve 6, outdoor electronic expansion valve 7, refrigerant discharge pipe 21, refrigerant inlet pipe 22, refrigerant discharge liquid pipe 23, refrigerant inlet liquid pipe 24, high-pressure cavity 25, low-pressure cavity 26, outer shell 250, inner shell 260. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0018] Please refer to Figure 1, this embodiment provides the following technical solution: A low-temperature air source heat pump system, including a compressor 1, a liquid receiver 2, an air-side heat exchanger 3, a water-side heat exchanger 4, a four-way valve 5, an indoor electronic expansion valve 6, and an outdoor electronic expansion valve 7. The suction side of the compressor 1 is connected to the refrigerant discharge gas pipe 21 of the liquid receiver 2. The four-way valve 5 is connected to the refrigerant input gas pipe 22 of the liquid receiver 2, the air-side heat exchanger 3, the water-side heat exchanger 4, and the discharge side of the compressor 1. The air-side heat exchanger 3 is connected to the outdoor electronic expansion valve 7. The outdoor electronic expansion valve 7 is connected to the refrigerant discharge liquid pipe 23 of the liquid receiver 2. The water-side heat exchanger 4 is connected to the indoor electronic expansion valve 6. The indoor electronic expansion valve 6 is connected to the refrigerant input liquid pipe 24 of the liquid receiver 2.

[0019] As a preferred embodiment of this embodiment, the liquid receiver 2 is composed of an outer shell and an inner shell, forming two inner and outer cavities. The outer cavity is a high-pressure cavity 25, with a pressure range of 1.6 - 4.4 MPa. The inner cavity is a low-pressure cavity 26, with a pressure range of 0.05 - 1.5 MPa.

[0020] As a preferred embodiment of this embodiment, the high-pressure cavity 25 is composed of an inner shell 260 and an outer shell 250. The low-pressure cavity 26 is solely constituted by the inner shell 260. It can be seen from Figure 1 that the inner shell 260 is disposed inside the outer shell 250 and fixedly connected to the top of the outer shell 250. The outer shell 250 is divided into two parts, the upper half is the upper shell, and the lower half is the lower shell. The bottom of the lower shell is also connected with legs.

[0021] As a preferred embodiment of this embodiment, the height difference between the bottoms of the high-pressure cavity 25 and the low-pressure cavity 26 is greater than 35 mm.

[0022] As a preferred embodiment of this embodiment, the refrigerant input gas pipe 22 and the refrigerant discharge gas pipe 21 are inserted into the interior of the low-pressure cavity 26 and fixedly connected to the top of the high-pressure cavity 25.

[0023] As a preferred embodiment of this embodiment, the refrigerant input liquid pipe 24 and the refrigerant output liquid pipe 23 are respectively fixedly connected to the bottom of the high-pressure cavity 25.

[0024] The heating operation principle of the low-temperature air source heat pump system in this embodiment: The refrigerant is compressed into a high-temperature and high-pressure gas by the compressor 1, enters the water-side heat exchanger 4 through the four-way valve 5, exchanges heat with water in the water-side heat exchanger 4, and becomes a medium-temperature and high-pressure liquid. After passing through the indoor unit electronic expansion valve 6, the liquid refrigerant enters the high-pressure chamber 25 of the liquid receiver 2 through the refrigerant input liquid pipe 24 and exchanges heat with the low-temperature and low-pressure gas-liquid mixed refrigerant in the low-pressure chamber 26 to achieve subcooling. Then, it is discharged from the liquid receiver 2 through the refrigerant discharge liquid pipe 23 and passes through the outdoor unit electronic expansion valve 7 to become a low-temperature and low-pressure liquid refrigerant. The liquid refrigerant exchanges heat with air through the air-side heat exchanger 3 (in actual operation, due to the lag in the adjustment of the outdoor unit electronic expansion valve 7, the heat exchange of the refrigerant in the air-side heat exchanger 3 is not sufficient), and becomes a low-temperature and low-pressure gas-liquid mixed refrigerant (with very little liquid refrigerant). The refrigerant passes through the four-way valve and enters the liquid receiver 2 through the refrigerant input gas pipe 22, and then exchanges heat with the high-temperature and high-pressure liquid refrigerant in the high-pressure chamber 25 to achieve secondary evaporation and become a gaseous refrigerant. Finally, it enters the suction side of the compressor 1 to complete a cycle.

[0025] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-temperature air source heat pump system, characterized in that: It includes a compressor, a liquid reservoir, an air-side heat exchanger, a water-side heat exchanger, a four-way valve, an indoor electronic expansion valve, and an outdoor electronic expansion valve. The suction side of the compressor is connected to the refrigerant discharge pipe of the liquid reservoir, the four-way valve is connected to the refrigerant input pipe of the liquid reservoir, the air-side heat exchanger, the water-side heat exchanger, and the exhaust side of the compressor. The air-side heat exchanger is connected to the outdoor electronic expansion valve, the outdoor electronic expansion valve is connected to the refrigerant discharge liquid pipe of the liquid reservoir, the water-side heat exchanger is connected to the indoor electronic expansion valve, and the indoor electronic expansion valve is connected to the refrigerant input liquid pipe of the liquid reservoir.

2. The low-temperature air source heat pump system according to claim 1, characterized in that: The liquid reservoir is composed of an outer shell and an inner shell to form two cavities, an outer cavity and an inner cavity. The outer cavity is a high-pressure cavity with a pressure range of 1.6-4.4MPa, and the inner cavity is a low-pressure cavity with a pressure range of 0.05-1.5MPa.

3. The low-temperature air source heat pump system according to claim 2, characterized in that: The high-pressure cavity is composed of an inner shell and an outer shell, and the low-pressure cavity is composed of the inner shell alone.

4. The low-temperature air source heat pump system according to claim 3, characterized in that: The height difference between the bottom of the high-pressure cavity and the bottom of the low-pressure cavity is greater than 35 mm.

5. The low-temperature air source heat pump system according to claim 4, characterized in that: The refrigerant input air pipe and the refrigerant exhaust air pipe are inserted into the low-pressure cavity and fixedly connected to the top of the high-pressure cavity.

6. The low-temperature air source heat pump system according to claim 1, characterized in that: The refrigerant input liquid pipe and the refrigerant output liquid pipe are respectively fixedly connected to the bottom of the high-pressure cavity.

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