Synergistic refrigerator system with self-oil-return ejector

Abstract

The invention discloses a self-oil-return ejector synergistic refrigerator system which comprises a compressor, a condenser, a drying filter, an oil return pipe set, an ejector, a gas-liquid separator, a throttling device, an evaporator, an oil return bend and a one-way valve. A high-pressure working medium after condensation and heat regeneration ejects a low-pressure working medium of the evaporator in the ejector, gas-liquid separation is performed after mixing and diffusion, intermediate pressure gas enters the compressor, the pressure ratio and power consumption are reduced, saturated liquid enters the evaporator for heat exchange after being throttled by the throttling device, the unit refrigerating capacity is improved, and meanwhile the system performance is improved through heat regeneration of an air return pipe and an outlet of the condenser. The one-way valve is connected with the evaporator and the compressor inlet, low pressure is formed at the compressor inlet during starting, the one-way valve is opened, lubricating oil accumulated in the evaporator returns to the compressor, and oil return difficulty caused by a gas-liquid separator is solved. By means of the time difference established by pressure at different positions when the system is started, the oil return difficulty is solved, the operation reliability is improved, and the novel refrigerator system is simple and efficient.

Description

Technical Field

[0001] The invention belongs to the field of refrigeration and cryogenic technology, and in particular relates to a self-return oil ejector efficiency-enhancing refrigerator system. Background Art

[0002] The current society has an increasing demand for efficient and environmentally friendly energy utilization solutions. How to improve the performance coefficient of refrigeration equipment and effectively develop energy-saving technologies for refrigeration equipment is the primary development direction of the refrigeration industry. Most of the household and commercial refrigerators currently in widespread use adopt a vapor compression refrigeration cycle, and the throttling device is a capillary tube. When the refrigerator refrigeration temperature is low, the throttling loss is large, the system refrigeration performance decreases, and the refrigerator consumes more power, which needs further improvement. The ejector has been commercially applied in CO2 supermarket refrigeration systems due to its simple structure, no moving parts, low cost, high expansion work recovery efficiency, and significant energy-saving effects. It also shows great energy-saving potential and development prospects in many refrigeration heat pump circulation systems.

[0003] For the compressor in the refrigeration system, lubricating oil is usually required for lubrication and cooling to reduce the risk of damage to its moving parts due to long-term operation. However, lubricating oil can be dissolved in any proportion of refrigerant. Lubricating oil is usually transported to the system pipeline along with high-pressure steam. Its viscosity is relatively high and it is easy to be adsorbed and accumulated on the inner surface of the evaporator, reducing the heat exchange effect of the evaporator. In addition, in the traditional ejector efficiency-enhancing refrigeration system, the low-pressure circuit usually contains a gas-liquid separator. The lubricating oil will follow the liquid phase into the evaporator in the gas-liquid separator and cannot return to the compressor, which will cause the compressor to lack oil and the evaporator to store oil after long-term operation. Seriously reduce the application of ejector efficiency-enhancing cycle in refrigeration systems. Although adding an oil separator to the compressor exhaust port can alleviate this problem to a certain extent, it cannot achieve 100% oil separation efficiency. There are still reliability issues in long-term operation. In addition, the oil separator is large in size, which is also a challenge for the compact compressor compartment structure layout of freezers and refrigerators. Moreover, for price-sensitive refrigeration equipment such as refrigerators and freezers, the economic efficiency of adding an oil separator is unacceptable; in addition, although adding a dedicated electric control valve to return oil regularly can achieve oil return, the increase of electric control valves will increase the cost of the valve body and the cost of electric control, and the economic efficiency is poor. Therefore, it is necessary to develop a solution that can automatically, reliably and cost-effectively recover the lubricating oil in the evaporator during the start-stop cycle of the freezer system, improve the reliability of the compressor, and ensure the long-term stable and efficient operation of the ejector-enhanced freezer refrigerator system. Summary of the invention

[0004] In order to improve the overall performance of the refrigerator system, reduce energy consumption, and realize automatic and efficient oil return of the system, the present invention proposes a self-return oil ejector efficiency-enhancing refrigerator system, which adopts an ejector to recover the expansion work of the high-pressure working fluid, and injects the low-pressure working fluid vapor from the evaporator and mixes and expands the pressure, so as to increase the suction pressure of the compressor and reduce the compressor pressure ratio and power consumption; a gas-liquid separator is used to separate the saturated liquid phase for further throttling, reduce the evaporator inlet dryness and specific enthalpy, increase the evaporator unit mass refrigeration capacity and heat exchange efficiency, and improve the overall performance of the system; a return air pipe and a condenser outlet are used for heat recovery to increase the flow of the evaporator and prevent liquid hammer in the compressor, and at the same time, the overall performance improvement effect caused by the performance attenuation of the ejector under some working conditions can be alleviated; an oil return bend and a one-way valve are used to connect the evaporator outlet and the compressor inlet, and during the short time when the compressor is started in the system start-stop cycle, the pressure difference formed by the low-pressure side of the compressor and the shutdown pressure of the evaporator is used to recover the lubricating oil accumulated in the evaporator to the compressor, so as to ensure long-term reliable operation of the system.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is:

[0006] A self-return oil ejector efficiency-enhancing refrigerator system, which uses an ejector to recover expansion work to achieve performance improvement; a one-way valve branch realizes efficient oil return during the refrigerator start-stop cycle to ensure the operating reliability of the refrigerator system; the refrigerator system includes a compressor 101, a condenser 102, a drying filter 103, a heat recovery pipe group 104, an ejector 105, a gas-liquid separator 106, a throttling device 107, an evaporator 108, an oil return bend 109 and a one-way valve 110;

[0007] The outlet of the compressor 101 is connected to the inlet of the condenser 102; the outlet of the condenser 102 is connected to the inlet of the filter drier 103; the outlet of the filter drier 103 is connected to the high-pressure side inlet of the heat recovery pipe group 104; the high-pressure side outlet of the heat recovery pipe group 104 is connected to the working flow inlet of the ejector 105; the outlet of the ejector 105 is connected to the inlet of the gas-liquid separator 106; the saturated gas phase outlet and the saturated liquid phase outlet of the gas-liquid separator 106 are respectively connected to the low-pressure side inlet of the heat recovery pipe group 104 and the inlet of the throttling device 107; the low-pressure side outlet of the heat recovery pipe group 104 is connected to the inlet of the compressor 101; the outlet of the throttling device 107 is connected to the inlet of the evaporator 108; the outlet of the evaporator 108 is respectively connected to the secondary flow inlet of the ejector 105 and the inlet of the return oil bend 109; the outlet of the return oil bend 109 is connected to the inlet of the one-way valve 110; the outlet of the one-way valve 110 is connected to the inlet of the compressor 101, so as to form a complete refrigerator system.

[0008] When the ejector 105 is in efficient refrigeration operation, the ejector recovers the expansion work of the high-pressure working fluid at the high-pressure side outlet of the heat recovery pipe group 104, and ejects the low-pressure working fluid vapor from the evaporator 108, which enters the gas-liquid separator 106 after mixing and expanding, thereby increasing the suction pressure of the compressor, reducing the compressor pressure ratio, and thus reducing the exhaust temperature and power consumption; the gas-liquid separator 106 separates the saturated liquid phase and enters the throttling device 107, which can reduce the inlet dryness and specific enthalpy of the evaporator 108, improve the heat exchange efficiency of the evaporator, and increase the unit mass refrigeration capacity; the heat recovery pipe group 104 The higher temperature liquid working medium at the outlet of the condenser 102 is exchanged with the lower temperature return air of the compressor 101 to achieve liquid supercooling, reduce the dryness of the two-phase working medium entering the gas-liquid separator 106, increase the flow rate on the evaporator side, and improve the cooling capacity. At the same time, the return air of the compressor 101 is moderately overheated to prevent liquid hammer. In addition, the increase in heat recovery alleviates the decline in the overall performance improvement effect caused by the performance attenuation of the ejector under some working conditions. In short, the reasonable configuration of the ejector 105, the gas-liquid separator 106 and the heat recovery pipe group 104 can improve the overall performance of the system.

[0009] When the refrigerator system is operating normally, the lubricating oil of the compressor 101 continuously flows through the ejector 105 with the working fluid and enters the gas-liquid separator 106. Since the lubricating oil is liquid, it cannot return to the inlet of the compressor 101 with the gas phase working fluid. Long-term operation will cause the lubricating oil to accumulate in the evaporator 108, resulting in oil shortage in the compressor 101, increased flow resistance in the evaporator 108, and severe flow attenuation, which in turn affects the reliability and performance of the refrigerator system. Therefore, at the end of the shutdown cycle of the refrigerator system, when the compressor 101 is started, the inlet of the compressor 101 forms the lowest pressure in the refrigerator system. The one-way valve 110 opens due to the pressure difference, and part of the working fluid and lubricating oil in the evaporator will quickly return to the compressor 101 through the oil return bend 109 in a short time; after running for a period of time, the pressure-boosting effect of the ejector 105 is obvious, and the pressure difference between the evaporator 108 outlet and the compressor 101 inlet is reduced, and the one-way valve 110 is closed; in this way, the oil return is realized by rationally utilizing the periodic start-stop operation characteristics of the refrigerator system, so that the refrigerator system does not need to add an oil separator or an oil return electric control valve, and automatic oil return is realized, which reduces the cost while ensuring the long-term operation reliability of the refrigerator system.

[0010] The gas-liquid separator 106 is arranged at the upper part of the refrigerator body, and the liquid phase outlet passes through the throttling device 107 and enters the evaporator 108.

[0011] The gas-liquid separator 106 adopts a cyclone type, a collision type or a gravity sedimentation type. The cyclone type has high separation efficiency and a simple structure; the collision type has a small volume and stable operation; the gravity sedimentation type has simple equipment and small resistance.

[0012] The outside of the gas-liquid separator 106 is wrapped with vacuum insulation material or high insulation material to prevent condensation on the outside of the refrigerator due to cold leakage.

[0013] The evaporator 108 is wound around the inner tank of the refrigerator from top to bottom, and each circle of the evaporator is tilted downward at an angle of not less than 3 degrees, which is conducive to the flow of lubricating oil; the outlet of the evaporator 108 is divided into two paths, and an insulating sleeve is added to the branch returning to the ejector inlet to prevent two-phase injection and cause pressure fluctuations; the other branch is first connected to the return oil bend 109, and the lubricating oil is accumulated here during operation to prepare for oil return; the outlet of the return oil bend 109 is connected to the inlet of the check valve 110; the minimum opening pressure of the check valve 110 is less than 50kPa, which ensures that the check valve can open normally and last for a sufficient time when a pressure difference is formed between the compressor 101 inlet and the evaporator 108.

[0014] The throttling device 107 is a capillary tube, a throttling short tube or an expansion valve. The capillary tube and the throttling short tube have low cost, simple and reliable structure; the expansion valve has high precision and good control effect.

[0015] The check valve 110 type adopts float type or piston type, which has simple design, reliable structure and high sensitivity.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] The present invention adopts an ejector 105 to recover the expansion work of the supercooled high-pressure working fluid at the outlet of the heat recovery pipe group 104, so as to increase the suction pressure of the compressor 101 and reduce the compressor pressure ratio and power consumption; the gas-liquid separator 106 separates the saturated liquid phase and enters the throttling device 107 for throttling, which can reduce the inlet dryness and specific enthalpy of the evaporator 108, and increase the evaporator's unit mass cooling capacity and heat exchange efficiency; the heat recovery pipe group 104 allows the return air of the compressor 101 and the outlet of the condenser 102 to recover heat, increase the evaporator flow and prevent liquid hammer, alleviate the overall performance improvement effect caused by the performance degradation of the ejector under some working conditions, and improve the overall performance of the system.

[0018] The freezer system with self-oil return capability can automatically and efficiently complete the oil return during the start-stop cycle of the freezer, and the oil return time is short, which does not affect the normal operation and refrigeration of the system. At the same time, only a one-way valve 110 needs to be added, which is suitable for the narrow space in the refrigerator and freezer compartment. There is no need to add an oil separator or an oil return electric control valve, and automatic oil return is achieved, which reduces the system cost while ensuring the long-term operation reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a system schematic diagram of the present invention.

[0020] Figure 2 It is the pressure-enthalpy diagram ph diagram of the system working process of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer and more concise, the present invention is further described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] The present invention provides a self-return oil ejector efficiency-enhancing refrigerator system, which uses an ejector to recover expansion work to achieve performance improvement; the one-way valve branch realizes efficient oil return during the refrigerator start-stop cycle to ensure the operational reliability of the refrigerator system; the refrigerator system includes a compressor 101, a condenser 102, a drying filter 103, a heat recovery pipe group 104, an ejector 105, a gas-liquid separator 106, a throttling device 107, an evaporator 108, an oil return bend 109 and a one-way valve 110; the outlet of the compressor 101 is connected to the inlet of the condenser 102; the outlet of the condenser 102 is connected to the inlet of the drying filter 103; the outlet of the drying filter 103 is connected to the high-pressure side inlet of the heat recovery pipe group 104; The high-pressure side outlet of the tube group 104 is connected to the working flow inlet of the ejector 105; the outlet of the ejector 105 is connected to the inlet of the gas-liquid separator 106; the saturated gas phase outlet and the saturated liquid phase outlet of the gas-liquid separator 106 are respectively connected to the low-pressure side inlet of the heat recovery tube group 104 and the inlet of the throttling device 107; the low-pressure side outlet of the heat recovery tube group 104 is connected to the inlet of the compressor 101; the outlet of the throttling device 107 is connected to the inlet of the evaporator 108; the outlet of the evaporator 108 is respectively connected to the secondary flow inlet of the ejector 105 and the inlet of the return oil bend 109; the outlet of the return oil bend 109 is connected to the inlet of the one-way valve 110; the outlet of the one-way valve 110 is connected to the inlet of the compressor 101, forming a complete refrigerator system. The high-pressure working fluid after condensation and heat recovery is injected into the low-pressure working fluid of the evaporator in the ejector, and the gas and liquid are separated after mixing and expanding. The intermediate-pressure gas enters the compressor, reducing the pressure ratio and power consumption. The saturated liquid enters the evaporator for heat exchange after being throttled by the throttling device, thereby increasing the unit refrigeration capacity. At the same time, the system performance is improved through heat recovery through the return air pipe and the condenser outlet. The one-way valve connects the evaporator and the compressor inlet. When starting, a low pressure is formed at the compressor inlet. The one-way valve opens, and the lubricating oil accumulated in the evaporator returns to the compressor, solving the oil return difficulty caused by the gas-liquid separator. The present invention utilizes the time difference between the pressures established at different positions when the system is started to solve the oil return difficulty and improve the operational reliability. It is a simple and efficient new refrigerator system.

[0023] Figure 2 The present invention provides a pressure-enthalpy diagram of the working process of a self-return oil ejector efficiency-enhancing refrigerator system. The specific working process is: the refrigerant superheated vapor ( Figure 2 1' point) is compressed to the condensing pressure ( Figure 2 2 points), and then enter the condenser 102; after exothermic liquefaction ( Figure 23), after the water and impurities are removed by the drying filter 103, it enters the high-pressure side of the heat recovery pipe group 104 and releases heat to the supercooled state ( Figure 2 3' point); then enters the ejector 105 above the freezer as a working fluid, the refrigerant expands in the ejector 105 nozzle, and the pressure energy is converted into kinetic energy, becoming a high-speed low-pressure two-phase flow ( Figure 2 4 points), saturated steam from the outlet of evaporator 108 ( Figure 2 7) is ejected as secondary flow, and after pressure loss ( Figure 2 8) is mixed with the primary flow in the mixing section of the ejector 105 ( Figure 2 4' point), enters the diffuser section of the ejector 105 for expansion, and the kinetic energy is converted back into pressure energy, and the pressure increases ( Figure 2 4" point) and enters the gas-liquid separator 106 above the refrigerator; the saturated gas phase ( Figure 2 1 point) enters the low-pressure side of the heat recovery pipe group 104 to absorb heat to the superheated state ( Figure 2 After returning to the compressor 101 inlet, the saturated liquid phase ( Figure 2 5 o'clock) enters the throttling device 107 and throttles to the evaporation temperature ( Figure 2 6 o'clock), and then enter the evaporator 108 that winds around the inner tank of the refrigerator from top to bottom to absorb heat and vaporize to saturated vapor ( Figure 2 7), is ejected by the ejector 105, completing the entire cycle. At this time, the evaporator 108 outlet ( Figure 2 The pressure at point 7) is lower than the compressor 101 inlet ( Figure 2 The check valve 110 is in the closed state. The refrigerator adopts start-stop control. When the temperature in the refrigerator rises to the target value, the shutdown cycle ends. When the compressor 101 is just started, its inlet quickly forms a low pressure, while the pressure in the evaporator 108 is still at the system shutdown equilibrium pressure. At this time, the outlet pressure of the evaporator 108 is higher than the inlet pressure of the compressor 101. The check valve 110 is opened, and the refrigerant entrains the lubricating oil through the oil return bend 109 and the check valve 110 and returns to the compressor 101. At this time, it is an oil return condition. As the pressure of the evaporator 108 decreases, the pressure boosting effect of the ejector 105 is obvious, and the pressure difference between the outlet of the evaporator 108 and the inlet of the compressor 101 decreases. The check valve 110 is closed, and the system is transformed into a normal operating condition.

Claims

1. A self-return oil ejector efficiency-enhancing refrigerator system, characterized in that: The ejector is used to recover expansion work to improve performance; the one-way valve branch realizes efficient oil return during the start-stop cycle of the refrigerator, thereby ensuring the operational reliability of the refrigerator system; the refrigerator system comprises a compressor (101), a condenser (102), a drying filter (103), a heat recovery pipe group (104), an ejector (105), a gas-liquid separator (106), a throttling device (107), an evaporator (108), an oil return bend (109) and a one-way valve (110); The outlet of the compressor (101) is connected to the inlet of the condenser (102); the outlet of the condenser (102) is connected to the inlet of the drying filter (103); the outlet of the drying filter (103) is connected to the high-pressure side inlet of the heat recovery pipe group (104); the high-pressure side outlet of the heat recovery pipe group (104) is connected to the working flow inlet of the ejector (105); the outlet of the ejector (105) is connected to the inlet of the gas-liquid separator (106); the saturated gas phase outlet and the saturated liquid phase outlet of the gas-liquid separator (106) are respectively connected to the heat recovery pipe group (104); 04) The low-pressure side inlet is connected to the inlet of the throttling device (107); the low-pressure side outlet of the heat return pipe group (104) is connected to the inlet of the compressor (101); the outlet of the throttling device (107) is connected to the inlet of the evaporator (108); the outlet of the evaporator (108) is respectively connected to the secondary flow inlet of the ejector (105) and the inlet of the return oil bend (109); the outlet of the return oil bend (109) is connected to the inlet of the check valve (110); the outlet of the check valve (110) is connected to the inlet of the compressor (101), forming a complete refrigerator system.

2. The self-return oil ejector efficiency-enhancing refrigerator system according to claim 1, characterized in that: When the ejector (105) is in high-efficiency refrigeration operation, the ejector recovers the expansion work of the high-pressure working fluid at the high-pressure side outlet of the heat recovery pipe group (104), and ejects the low-pressure working fluid vapor from the evaporator (108), and after mixing and expanding, enters the gas-liquid separator (106), thereby increasing the suction pressure of the compressor, reducing the compressor pressure ratio, and thus reducing the exhaust temperature and power consumption; the gas-liquid separator (106) separates the saturated liquid phase and enters the throttling device (107), which can reduce the inlet dryness and specific enthalpy of the evaporator (108), improve the heat exchange efficiency of the evaporator, and increase the unit mass refrigeration capacity; the heat recovery pipe group (104 ) allows the liquid working medium at the outlet of the condenser (102) with a higher temperature to exchange heat with the return air from the compressor (101) with a lower temperature, thereby achieving liquid supercooling, reducing the dryness of the two-phase working medium entering the gas-liquid separator (106), increasing the flow rate on the evaporator side, and improving the refrigeration capacity. At the same time, the return air from the compressor (101) is moderately overheated to prevent liquid hammer. In addition, the increase in heat recovery alleviates the decline in the overall performance improvement effect caused by the performance degradation of the ejector under certain working conditions. In short, through the reasonable configuration of the ejector (105), the gas-liquid separator (106) and the heat recovery pipe group (104), the overall performance of the system can be improved.

3. The self-return oil ejector efficiency-enhancing refrigerator system according to claim 1, characterized in that: When the downtime period of the refrigerator system ends and the compressor (101) is started, the lowest pressure in the refrigerator system is formed at the inlet of the compressor (101), and the one-way valve (110) is opened due to the pressure difference. In a short period of time, part of the working fluid and lubricating oil in the evaporator will quickly return to the compressor (101) through the oil return bend (109); after running for a period of time, the pressure boosting effect of the ejector (105) is obvious, the pressure difference between the outlet of the evaporator (108) and the inlet of the compressor (101) decreases, and the one-way valve (110) is closed; in this way, the periodic start-stop operation characteristics of the refrigerator system are reasonably utilized to realize oil return, so that the refrigerator system does not need to add an oil separator or an oil return electric control valve, and automatic oil return is realized, thereby ensuring the long-term operation reliability of the refrigerator system while reducing the cost.

4. The self-return oil ejector efficiency-enhancing refrigerator system according to claim 1 is characterized in that: The gas-liquid separator (106) is arranged at the upper part of the refrigerator body, and the liquid phase outlet passes through the throttling device (107) and enters the evaporator (108).

5. The self-return oil ejector efficiency-enhancing refrigerator system according to claim 1 is characterized in that: The gas-liquid separator (106) is of cyclone type, collision type or gravity sedimentation type.

6. The self-return oil ejector efficiency-enhancing refrigerator system according to claim 1 is characterized in that: The outside of the gas-liquid separator (106) is wrapped with vacuum insulation material or high insulation material to prevent condensation on the outside of the refrigerator due to cold leakage.

7. The self-return oil ejector efficiency-enhancing refrigerator system according to claim 1, characterized in that: The evaporator (108) is wound around the inner tank of the refrigerator from top to bottom, and each circle of the evaporator is tilted downward at an angle of not less than 3 degrees, which is conducive to the flow of lubricating oil; the outlet of the evaporator (108) is divided into two paths, and a thermal insulation sleeve is added to the branch returning to the ejector inlet to prevent the occurrence of two-phase injection and cause pressure fluctuations; the other branch is first connected to the return oil bend (109), and the lubricating oil is accumulated here during the operation process to prepare for the return oil; the outlet of the return oil bend (109) is connected to the inlet of the one-way valve (110); the minimum opening pressure of the one-way valve (110) is less than 50kPa.

8. The self-return oil ejector efficiency-enhancing refrigerator system according to claim 1, characterized in that: The throttling device (107) is a capillary tube, a throttling short tube or an expansion valve.

9. The self-return oil ejector efficiency-enhancing refrigerator system according to claim 1, characterized in that: The check valve (110) is a float type or a piston type.

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