A control method for increasing suction superheat degree of a system by recovering waste heat of a compressor

Abstract

The application discloses a control method for increasing system suction superheat degree by recovering waste heat of a compressor, wherein an auxiliary electronic expansion valve is controlled according to the temperature difference between the suction port of the compressor and the outlet of the auxiliary electronic expansion valve, so as to control the flow of refrigerant in the waste heat micro-channel. The micro-channel heat exchanger is arranged on the surface of the compressor, absorbs the heat generated during the operation of the compressor through radiation transmission, and uses the heat to perform secondary heating on the frozen oil and liquid refrigerant at the bottom of the gas-liquid separator, so that the frozen oil and liquid refrigerant are returned to the suction port of the compressor, the low-pressure pressure of the compressor is obviously increased, the liquid refrigerant at the bottom of the gas-liquid separator is prevented from returning to the compressor through the oil return pipe and causing damage to the compressor, the suction superheat degree of the compressor is improved, the scope of the system main electronic expansion valve is increased, and the refrigerating capacity and the heating capacity of the system are improved.

Description

Technical Field

[0001] The invention relates to a control method for increasing the system suction superheat by recovering compressor waste heat. Background Art

[0002] At present, all heat pump units and air conditioners use compressors. Whether they are working for cooling in the summer or heating in the winter, the heat generated by the compressor will be dissipated into the outdoor air through the surface of the compressor itself. If this part of the waste heat can be utilized, it will not only ensure the reliability of the unit and improve the performance of the unit, but also reduce the greenhouse effect on the outside world. Summary of the Invention

[0003] In response to the above problems, the present invention provides a control method for increasing the system suction superheat by recovering compressor waste heat, which effectively solves the problems pointed out in the background technology.

[0004] The technical solution adopted in the present invention is:

[0005] A control method for increasing the system suction superheat by utilizing compressor waste heat recovery. The system includes an indoor unit and an outdoor unit. The outdoor unit includes a compressor, a four-way valve, an outdoor heat exchanger, a main electronic expansion valve, a liquid reservoir, a gas-liquid separator, and an auxiliary electronic expansion valve. The bottom of the gas-liquid separator is provided with an oil return pipe. The surface of the compressor is provided with a microchannel heat exchanger. One end of the microchannel heat exchanger is connected to the oil return pipe, and the other end is connected to the suction port of the compressor. The temperature of the auxiliary electronic expansion valve inlet is defined as TH4, the temperature of the compressor suction port is defined as TH5, and the ambient temperature is defined as T 环 , the control method is as follows: a) In heating mode: when the compressor frequency is greater than 35Hz and the compressor exhaust temperature is greater than T 环 When the temperature is +25℃, the auxiliary electronic expansion valve is controlled to open according to the initial opening, and the auxiliary electronic expansion valve is controlled as follows: a1) When TH5> TH4+3, the auxiliary electronic expansion valve is controlled to increase the opening by x, until the auxiliary electronic expansion valve reaches the maximum opening; a2) When TH5< TH4+3, the auxiliary electronic expansion valve is controlled to decrease the opening by y, until the auxiliary electronic expansion valve reaches the minimum opening; a3) When TH5= TH4+3, the auxiliary electronic expansion valve is controlled to maintain the current opening unchanged; When the compressor frequency is lower than 35Hz and the compressor exhaust temperature is lower than T 环 +25℃, the auxiliary electronic expansion valve is controlled to close; b) In cooling mode: when the compressor frequency is greater than 35Hz and the compressor exhaust temperature is greater than T 环When the temperature is +15℃, the auxiliary electronic expansion valve is controlled to open according to the initial opening, and the auxiliary electronic expansion valve is controlled as follows: b1) When TH5> TH4+3, the auxiliary electronic expansion valve is controlled to increase the opening by x, until the auxiliary electronic expansion valve reaches the maximum opening; b2) When TH5< TH4+3, the auxiliary electronic expansion valve is controlled to decrease the opening by y, until the auxiliary electronic expansion valve reaches the minimum opening; b3) When TH5= TH4+3, the auxiliary electronic expansion valve is controlled to maintain the current opening unchanged; When the compressor frequency is lower than 35Hz and the compressor exhaust temperature is lower than T 环 When the temperature is +15℃, the auxiliary electronic expansion valve is controlled to close.

[0006] Preferably, the x = TH5-(TH4+3), and the y = TH4+5- TH5.

[0007] Preferably, the initial opening of the auxiliary electronic expansion valve is 100 steps.

[0008] Preferably, the oil return pipe is provided with a fourth temperature sensor at the inlet of the auxiliary electronic expansion valve, and the detected temperature is TH4. The fifth temperature sensor is provided at the suction port of the compressor, and the detected temperature is TH5. The auxiliary electronic expansion valve is controlled by the temperature difference between the two temperature sensors, thereby controlling the flow of the refrigerant inside the waste heat microchannel.

[0009] The present invention sets a microchannel heat exchanger on the surface of the compressor, absorbs the heat generated by the compressor when it is working through radiation transfer, and uses the heat to secondary heat the refrigeration oil and liquid refrigerant at the bottom of the gas-liquid separator, and then returns them to the compressor suction port, thereby significantly improving the low-pressure pressure of the compressor. It can not only prevent the liquid refrigerant at the bottom of the gas-liquid separator from returning to the compressor through the return oil pipe and causing damage to the compressor, but also increase the suction superheat of the compressor, thereby increasing the range of action of the system's main electronic expansion valve and improving the system's cooling capacity and heating capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural diagram of the heat pump system of the present invention. DETAILED DESCRIPTION

[0011] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0012] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0013] In addition, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0014] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise explicitly specified.

[0015] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0016] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0017] The present invention will be further described in detail below through specific embodiments with reference to the accompanying drawings.

[0018] like Figure 1 As shown, the structure of the heat pump system of the present invention is shown. The system includes an indoor unit 1 and an outdoor unit 2. The outdoor unit 2 includes a compressor 21, a four-way valve 22, an outdoor heat exchanger 23, a main electronic expansion valve 24, a liquid reservoir 25, a gas-liquid separator 26 and an auxiliary electronic expansion valve 27. The bottom of the gas-liquid separator 26 is provided with an oil return pipe 28, and the oil return pipe 28 is provided with a fourth temperature sensor 210 at the inlet of the auxiliary electronic expansion valve 27. The surface of the compressor 21 is provided with a microchannel heat exchanger 29, and the surface of the microchannel heat exchanger 29 can be provided with thermal insulation cotton to improve the microchannel heat exchanger. 29 is the utilization rate of the waste heat of the compressor 21. One end of the microchannel heat exchanger 29 is connected to the return oil pipe 28, and the other end is connected to the intake port of the compressor 21. The intake port of the compressor 21 is provided with a fifth temperature sensor 211. For such a heat pump system, the present invention discloses a control method for increasing the system intake superheat by recovering the waste heat of the compressor. The temperature of the inlet of the auxiliary electronic expansion valve 27 is defined as TH4, which is detected by the fourth temperature sensor 210. The temperature of the intake port of the compressor 21 is defined as TH5, which is detected by the fifth temperature sensor 211. The ambient temperature is T 环 , the control method is as follows: a) In heating mode: when the frequency of the compressor 21 is greater than 35Hz and the exhaust temperature of the compressor 21 is greater than T 环 When the temperature is +25℃, the auxiliary electronic expansion valve 27 is controlled to open according to the initial opening, and the initial opening is preferably 100 steps, and the auxiliary electronic expansion valve 27 is controlled as follows: a1), when TH5> TH4+3, the auxiliary electronic expansion valve 27 is controlled to increase the opening, and the increase value is x, until the auxiliary electronic expansion valve 27 reaches the maximum opening; a2), when TH5< TH4+3, the auxiliary electronic expansion valve 27 is controlled to decrease the opening, and the decrease value is y, until the auxiliary electronic expansion valve 27 reaches the minimum opening; a3), when TH5= TH4+3, the auxiliary electronic expansion valve 27 is controlled to maintain the current opening unchanged; When the frequency of the compressor 21 is lower than 35Hz and the exhaust temperature of the compressor 21 is lower than T 环 When the temperature is +25℃, the auxiliary electronic expansion valve 27 is controlled to close.

[0019] The present invention recovers the waste heat released by the compressor during work and heat production, reheats the refrigeration oil and liquid refrigerant at the bottom of the gas-liquid separator, and then returns them to the compressor suction port, thereby significantly increasing the low-pressure pressure of the compressor. This not only prevents the liquid refrigerant at the bottom of the gas-liquid separator from returning to the compressor through the return oil pipe and causing damage to the compressor, but also increases the suction superheat of the compressor, thereby increasing the range of the system's main electronic expansion valve and increasing the heating capacity of the system. b) In cooling mode: When the frequency of compressor 21 is greater than 35Hz and the exhaust temperature of compressor 21 is greater than T 环 When the temperature is +15℃, the auxiliary electronic expansion valve 27 is controlled to open according to the initial opening, and the initial opening is preferably 100 steps, and the auxiliary electronic expansion valve 27 is controlled as follows: b1) When TH5>TH4+3, the auxiliary electronic expansion valve 27 is controlled to increase the opening, and the increase value is x, until the auxiliary electronic expansion valve 27 reaches the maximum opening; b2) When TH5< TH4+3, the auxiliary electronic expansion valve 27 is controlled to decrease the opening, and the decrease value is y, until the auxiliary electronic expansion valve 27 reaches the minimum opening; b3) When TH5= TH4+3, the auxiliary electronic expansion valve 27 is controlled to maintain the current opening unchanged; When the frequency of the compressor 21 is lower than 35Hz and the exhaust temperature of the compressor 21 is lower than T 环 When the temperature is +15℃, the auxiliary electronic expansion valve 27 is controlled to close.

[0020] Where x and y can be set as constants or according to TH 5和 Calculation of TH4 yields: x = TH5-(TH4+3), y = TH4+5- TH5.

[0021] The present invention recovers the waste heat released by the compressor during refrigeration work and provides a certain amount of superheated gas refrigerant to the compressor, thereby preventing damage to the compressor due to liquid return, ensuring the reliability of the compressor and achieving the purpose of energy saving and consumption reduction.

[0022] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and is subject to numerous variations. All variations that can be directly derived or conceived by a person of ordinary skill in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A control method for increasing the system suction superheat by utilizing compressor waste heat recovery, characterized in that: The system includes an indoor unit (1) and an outdoor unit (2), wherein the outdoor unit (2) includes a compressor (21), a four-way valve (22), an outdoor heat exchanger (23), a main electronic expansion valve (24), a liquid reservoir (25), a gas-liquid separator (26) and an auxiliary electronic expansion valve (27), wherein the bottom of the gas-liquid separator (26) is provided with an oil return pipe (28), and the surface of the compressor (21) is provided with a microchannel heat exchanger (29), one end of the microchannel heat exchanger (29) is connected to the oil return pipe (28), and the other end is connected to the air intake of the compressor (21), and the temperature at the inlet of the auxiliary electronic expansion valve (27) is defined as TH4, and the oil return pipe (28) is provided with a fourth temperature sensor (210) at the inlet of the auxiliary electronic expansion valve (27), and the detected temperature is TH4, the temperature at the air intake of the compressor (21) is TH5, and the ambient temperature is T 环 , and its control method is as follows: a) In heating mode: when the frequency of the compressor (21) is greater than 35Hz and the exhaust temperature of the compressor (21) is greater than T 环 When the temperature is +25℃, the auxiliary electronic expansion valve (27) is controlled to open according to the initial opening, and the auxiliary electronic expansion valve (27) is controlled as follows: a1), when TH5> TH4+3, the auxiliary electronic expansion valve (27) is controlled to increase the opening, the increase value is x, until the auxiliary electronic expansion valve (27) reaches the maximum opening; a2), when TH5< TH4+3, the auxiliary electronic expansion valve (27) is controlled to decrease the opening, the decrease value is y, until the auxiliary electronic expansion valve (27) reaches the minimum opening; a3), when TH5= TH4+3, the auxiliary electronic expansion valve (27) is controlled to maintain the current opening unchanged; when the frequency of the compressor (21) is lower than 35Hz and the exhaust temperature of the compressor (21) is lower than T 环 +25℃, the auxiliary electronic expansion valve (27) is controlled to close; b) In cooling mode: when the frequency of the compressor (21) is greater than 35Hz and the exhaust temperature of the compressor (21) is greater than T 环 When the temperature is +15℃, the auxiliary electronic expansion valve (27) is controlled to open according to the initial opening, and the auxiliary electronic expansion valve (27) is controlled as follows: b1), when TH5> TH4+3, the auxiliary electronic expansion valve (27) is controlled to increase the opening, the increase value is x, until the auxiliary electronic expansion valve (27) reaches the maximum opening; b2), when TH5< TH4+3, the auxiliary electronic expansion valve (27) is controlled to decrease the opening, the decrease value is y, until the auxiliary electronic expansion valve (27) reaches the minimum opening; b3), when TH5= TH4+3, the auxiliary electronic expansion valve (27) is controlled to maintain the current opening unchanged; when the frequency of the compressor (21) is lower than 35Hz and the exhaust temperature of the compressor (21) is lower than T 环 When the temperature is +15℃, the auxiliary electronic expansion valve (27) is controlled to close.

2. A control method for increasing system suction superheat by utilizing compressor waste heat recovery according to claim 1, characterized in that: The x = TH5-(TH4+3), the y = TH4+5- TH5.

3. The control method for increasing system suction superheat by utilizing compressor waste heat recovery according to claim 1, characterized in that: The initial opening of the auxiliary electronic expansion valve (27) is 100 steps.

4. The control method for increasing system suction superheat by utilizing compressor waste heat recovery according to claim 1, characterized in that: A fifth temperature sensor (211) is provided at the air intake of the compressor (21), and the detected temperature is TH5.

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