Transcritical COheat pump oil return system

Abstract

The utility model relates to the technical field of COheat pump oil return, in particular to a transcritical COheat pump oil return system which comprises a COcompressor, an air cooler and a gas-liquid separator. The COcompressor is communicated and fixed with an auxiliary air cooler through an exhaust pipe, the auxiliary air cooler is communicated and fixed with an air cooler through an exhaust pipe, an air cooler oil return pipe to a liquid pipe is additionally arranged at the bottom of a liquid collecting pipe of the air cooler, the end part of the liquid pipe is communicated and fixed with a heat regenerator, and an oil filter is additionally arranged in front of an air return port of the COcompressor. The heat regenerator is communicated and fixed with the oil filter through a gas return pipe; and an electromagnetic valve and a gas-liquid separator oil return pipe are additionally arranged at the bottom of the gas-liquid separator and are connected to a gas return port of the COcompressor. Lubricating oil in the air cooler is recycled through the air cooler oil return pipe, the lubricating oil enters the evaporator through the liquid pipe section, and the liquid refrigerant and the liquid lubricating oil return to the COcompressor for refrigeration after being separated and collected by the gas-liquid separator, so that liquid impact of the COcompressor is prevented, and normal operation of a refrigeration system is guaranteed. And meanwhile, the liquid level is monitored through the oil level sensor, the electromagnetic valve is opened to recover the lubricating oil when the set height is reached, and therefore it is guaranteed that enough lubricating oil is used for mechanical lubrication in the operation process of the COcompressor.

Description

TECHNICAL FIELD

[0001] The utility model relates to CO2 heat pump oil return technical field, concretely is a kind of transcritical CO2 heat pump oil return system. BACKGROUND

[0002] Because of its efficient electric heat conversion performance, heat pump is an energy equipment that can effectively "decarbonize". The demand for hydrofluorocarbon (HFC) refrigerants in heat pump heating brings environmental problems such as greenhouse effect and ozone layer depletion. Therefore, the development of heat pump is challenged by the problem of refrigerant replacement. Among the many alternative working substances, CO2, as a natural working substance, has an ozone depletion potential (ODP) value of 0 and a global warming potential (GWP) value of 1. It is low-cost, easy to obtain, non-toxic and stable. Compared with traditional freon working substance heat pump system, CO2 heat pump has the advantages of wide heating water temperature range and less environmental temperature restriction. It can effectively reduce the consumption of fossil energy and improve energy utilization efficiency, thereby helping to achieve carbon neutrality. However, the transcritical CO2 heat pump system currently has the problem of lack of lubricating oil in the compressor after a long time of operation, which leads to excessive noise, vibration or current in the compressor, and even causes wear of internal mechanical components, causing irreversible damage to the compressor. The common design on the market is to set an oil separator on the exhaust side of the CO2 heat pump system for oil return. Its working principle is as follows: after the refrigerant is compressed into high-pressure high-temperature gas by the compressor, it enters the oil separator. The oil separator separates the lubricating oil mixed in the gas refrigerant under the action of gravity through the principle of reducing the flow of exhaust refrigerant and changing the direction of airflow. Generally, when the airflow speed is below 1 m / s, the oil particles with a diameter of more than 0.2 mm in the steam can be separated out and dropped to the bottom of the container. The bottom is provided with an oil return pipeline to the compressor and is equipped with an electromagnetic valve or a float valve to control the return of the lubricating oil to the compressor.

[0003] However, some CO2 compressors now work in the transcritical region, with exhaust temperature as high as 120-140 degrees Celsius and pressure of 100 bar. Therefore, the diameter of the lubricating oil particles mixed in the gas refrigerant is much smaller than 0.2 mm, and the oil cannot be effectively separated, resulting in poor oil return effect and lack of oil in the compressor, which reduces the working efficiency of the compressor and even causes equipment damage, increased power consumption and unit shutdown. To ensure sufficient lubricating oil in the compressor during operation, some maintenance personnel add a large amount of lubricating oil to the compressor, which causes a large amount of lubricating oil particles mixed in the gas refrigerant to form an oil film on the surface of the heat transfer wall of the gas cooler and evaporator. Because the heat transfer coefficient of lubricating oil is much lower than that of copper pipe, the formation of oil film increases the heat transfer resistance of the gas cooler and evaporator, resulting in reduced heat transfer effect of the gas cooler and evaporator and affecting the refrigeration effect of the system. The high temperature on the exhaust side of the transcritical CO2 heat pump system accelerates the oxidation of the lubricating oil and even carbonization, resulting in the formation of sediment and reducing the stability of the oil, which affects the lubricating performance and the service life of mechanical components. Therefore, we propose a transcritical CO2 heat pump oil return system to solve the above problems. Utility model content

[0004] The utility model discloses a cross critical CO2 heat pump oil return system to solve the problem in the foregoing background art.

[0005] To realize the above-mentioned purpose, the utility model provides the following technical scheme: a cross critical CO2 heat pump oil return system, including CO2 compressor, gas cooler and gas-liquid separator, the CO2 compressor is connected with the auxiliary gas cooler through the exhaust pipe and is fixed, the auxiliary gas cooler is connected with the gas cooler through the exhaust pipe and is fixed, the gas cooler liquid collecting pipe bottom additionally sets up the gas cooler oil return pipe to the liquid pipe, the end of the liquid pipe is connected with the heat regenerator and is fixed, and the oil filter is additionally set before the CO2 compressor gas inlet, the heat regenerator is connected with the oil filter through the gas pipe and is fixed, the gas-liquid separator bottom additionally sets up the electromagnetic valve and the gas-liquid separator oil return pipe is connected with the CO2 compressor gas inlet.

[0006] Further preferably, the auxiliary gas cooler is fixedly connected with an auxiliary cooling fan on one side.

[0007] Further preferably, the heat regenerator is communicated and fixed with a drying filter through a pipeline.

[0008] Further preferably, the drying filter is communicated and fixed with an electronic expansion valve through a pipeline, and the electronic expansion valve is communicated and fixed with an evaporator through a pipeline.

[0009] Further preferably, the gas-liquid separator is communicated and fixed with the evaporator through a pipeline.

[0010] Compared with the prior art, the utility model has the beneficial effects that: the utility model recovers the lubricating oil in the gas cooler through the gas cooler oil return pipe, makes it to the evaporator through the liquid pipe section, then separates and collects the evaporator return CO2 compressor refrigeration liquid refrigerant and liquid lubricating oil through the gas-liquid separator, prevents CO2 compressor liquid strike to guarantee the normal operation of the refrigeration system, monitors the liquid level through the oil level sensor, opens the electromagnetic valve to recover the lubricating oil when reaching the set height, thereby guaranteeing that there is enough lubricating oil for mechanical lubrication during the operation of the CO2 compressor, the application has little change to the original system, low new construction or reconstruction cost, convenient to use, reliable control, meets the normal oil return demand of the cross critical CO2 heat pump system under the condition of not increasing additional energy consumption and not wasting the service life of the system components. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is the front view three-dimensional structure schematic diagram of the utility model.

[0012] In the figure: 1, CO2 compressor; 2, auxiliary cooling fan; 3, auxiliary air cooler; 4, air cooler; 5, regenerator; 6, dry filter; 7, electronic expansion valve; 8, evaporator; 9, gas-liquid separator; 10, oil filter; 11, exhaust pipe; 12, air cooler oil return pipe; 13, liquid pipe; 14, solenoid valve; 15, gas-liquid separator oil return pipe; 16, gas return pipe. DETAILED DESCRIPTION

[0013] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0014] Embodiment, please refer to Figure 1The utility model provides a kind of technical scheme: a kind of transcritical CO2 heat pump oil return system, including CO2 compressor 1, gas cooler 4 and gas-liquid separator 9, CO2 compressor 1 is connected with and fixed with auxiliary gas cooler 3 by exhaust pipe 11, auxiliary gas cooler 3 is connected with and fixed with gas cooler 4 by exhaust pipe 11, high-temperature gas refrigerant is heat-exchanged after gas cooler 4, according to the characteristics that the lubricating oil particles mixed in gas are increased with temperature reduction according to their own viscosity, easy to gather in the bottom of gas cooler 4 collecting pipe, the bottom of gas cooler 4 collecting pipe is additionally provided with gas cooler oil return pipe 12 to liquid pipe 13, when lubricating oil gathers in the bottom of gas cooler 4 collecting pipe to gas cooler oil return pipe 12, liquid level forms liquid seal, according to the pressure balance characteristics of connected pipe section, lubricating oil is sent into liquid pipe 13 by gas cooler oil return pipe 12 and participates in refrigerant circulation, and finally returns to CO2 compressor 1, reaches the purpose of returning oil, the end of liquid pipe 13 is connected with and fixed with regenerator 5, CO2 compressor 1 is additionally provided with oil filter 10 before gas inlet, prevents that impurity or carbonized lubricating oil in pipeline enters compressor, causes compressor mechanical damage, regenerator 5 is connected with and fixed with oil filter 10 by return gas pipe 16, the bottom of gas-liquid separator 9 is additionally provided with solenoid valve 14 and gas-liquid separator oil return pipe 15 is connected to CO2 compressor 1 gas inlet, gas-liquid separator 9 separates the refrigerant returned to CO2 compressor 1 into gas and liquid, only makes gas return to CO2 compressor 1, to avoid liquid state refrigerant to enter CO2 compressor 1 and cause liquid strike;The liquid separated by gas-liquid separator 9 is composed of liquid state refrigerant and lubricating oil, by setting oil level sensor control solenoid valve 14, when liquid in gas-liquid separator 9 exceeds the set liquid level, oil level sensor transmits signal to control system and opens solenoid valve 14, liquid is through Q type gas-liquid separator oil return pipe 15 to CO2 compressor 1 suction port, Q type gas-liquid separator oil return pipe 15 selects 3 / 8 '' copper pipe, it is found during unit test that Q type gas-liquid separator oil return pipe 15 has throttling effect to liquid state refrigerant in liquid, and suction temperature is increased after gaseous refrigerant is heat-exchanged by regenerator 5, can guarantee that liquid state refrigerant in reflux liquid is changed into gaseous state and prevents compressor liquid strike, liquid lubricating oil returns to CO2 compressor 1 with gaseous refrigerant and reaches the purpose of returning oil.

[0015] In the embodiment, specifically: one side of the auxiliary gas cooler 3 is fixedly connected with an auxiliary cooling fan 2.

[0016] In the embodiment, specifically: the regenerator 5 is communicated and fixed with a drying filter 6 through a pipeline.

[0017] In the embodiment, specifically: the drying filter 6 is communicated and fixed with an electronic expansion valve 7 through a pipeline.

[0018] In the embodiment, specifically: the gas-liquid separator 9 is communicated and fixed with the evaporator 8 through a pipeline.

[0019] The utility model discloses a recovery of the lubricating oil in the gas cooler 4 through the setting of the gas cooler oil return pipe 12, makes it to the evaporator 8 in the liquid pipe section, and then the refrigerant and liquid lubricating oil of CO2 compressor 1 are returned to the gas-liquid separator 9 separation and collection evaporator 8 after, prevent CO2 compressor 1 liquid strike to guarantee the normal operation of refrigeration system, and the liquid level is monitored through oil level sensor, and when reaching the set height, open solenoid valve 14 and recover lubricating oil, thereby guaranteeing that there is enough lubricating oil for mechanical lubrication in the operation process of CO2 compressor 1, and satisfying the normal oil recovery demand of transcritical CO2 heat pump system.

[0020] Although the embodiments of the utility model have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the utility model, and the scope of the utility model is defined by the appended claims and their equivalents.

Claims

1. A transcritical CO2 heat pump oil return system comprising a CO2 compressor (1), an air cooler (4) and a gas-liquid separator (9), characterized in that: The CO2 compressor (1) is communicated and fixed with the auxiliary air cooler (3) through the exhaust pipe (11), the auxiliary air cooler (3) is communicated and fixed with the air cooler (4) through the exhaust pipe (11), the air cooler (4) is additionally provided with the air cooler oil return pipe (12) at the bottom of the liquid collecting pipe to the liquid pipe (13), the end of the liquid pipe (13) is communicated and fixed with the regenerator (5), the oil filter (10) is additionally provided in front of the CO2 compressor (1) gas inlet, the regenerator (5) is communicated and fixed with the oil filter (10) through the gas return pipe (16), the electromagnetic valve (14) and the gas-liquid separator oil return pipe (15) are additionally provided at the bottom of the gas-liquid separator (9) and connected to the CO2 compressor (1) gas inlet.

2. A transcritical CO2 heat pump oil return system according to claim 1, characterized in that: One side of the auxiliary air cooler (3) is fixedly connected with the auxiliary cooling fan (2).

3. A transcritical CO2 heat pump oil return system according to claim 2, characterized in that: The regenerator (5) is communicated and fixed with the drying filter (6) through the pipeline.

4. A transcritical CO2 heat pump oil return system according to claim 3, characterized in that: The drying filter (6) is communicated and fixed with the electronic expansion valve (7) through the pipeline, and the electronic expansion valve (7) is communicated and fixed with the evaporator (8) through the pipeline.

5. A transcritical CO2 heat pump oil return system according to claim 4, characterized in that: The gas-liquid separator (9) is communicated and fixed with the evaporator (8) through the pipeline.

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