General defrosting device for air conditioner heat exchanger defrosting experiment

Abstract

This invention discloses a universal defrosting device for defrosting experiments on air conditioner heat exchangers, comprising a low-temperature defrosting system, a high-temperature defrosting system, and a control system. The low-temperature defrosting system and the high-temperature defrosting system are connected in parallel. Both systems use ethylene glycol solution as a medium. The solution outlets of both systems are connected to the inlet of the air conditioner heat exchanger, and their inlets are connected to the outlet of the heat exchanger. The control system controls the operation of the entire device and can switch the connection between the low-temperature defrosting system, the high-temperature defrosting system, and the air conditioner heat exchanger, thereby allowing for separate defrosting or defrosting experiments on the heat exchanger. This device has a simple structure, is easy to operate, stable and fast, highly versatile, and has a wide range of applications.

Description

Technical Field

[0001] This invention relates to experimental equipment for air conditioning heat exchangers, specifically a general-purpose defrosting device for defrosting experiments on air conditioning heat exchangers. Background Technology

[0002] In recent years, both domestic and international air conditioning industries have begun to study the changes in heat exchange efficiency of heat exchangers during frosting and the impact on operating conditions during defrosting. Their methods for studying frosting and defrosting phenomena typically include using simulation software to analyze the phenomena or directly building air conditioning systems for actual observation.

[0003] The simulation experiment is an idealized state based on the energy heat transfer conservation formula and the molecular diffusion model. It requires a lot of prior model accumulation and ignores the influence of actual environmental factors and the condition of the heat exchanger itself.

[0004] Directly building a refrigerant system requires consideration of the selection of components such as compressors, expansion valves, and condensers, as well as the design of system piping dimensions. This cannot meet the testing requirements of heat exchangers with a wide range of capabilities. Furthermore, the stabilization process of parameters such as refrigerant temperature and pressure at the inlet and outlet of the tested component during defrosting experiments is relatively slow. Therefore, building a refrigerant system has certain limitations and is time-consuming and material-intensive. Summary of the Invention

[0005] The purpose of this invention is to provide a universal defrosting device for defrosting experiments of air conditioning heat exchangers. The device has a simple structure, is easy to operate, stable and fast, highly versatile, and has a wide range of applications. It can be used for defrosting or defrosting experiments of air conditioning heat exchangers.

[0006] The above-mentioned objective of the present invention is achieved through the following technical solution: a universal defrosting device for defrosting experiments of air conditioning heat exchangers, characterized in that: the device includes a low-temperature defrosting system, a high-temperature defrosting system, and a control system; the low-temperature defrosting system and the high-temperature defrosting system are arranged in parallel; both the low-temperature defrosting system and the high-temperature defrosting system use ethylene glycol solution as a medium; the solution outlets of both the low-temperature defrosting system and the high-temperature defrosting system are connected to the inlet of the air conditioning heat exchanger; the solution inlet of both the low-temperature defrosting system and the high-temperature defrosting system is connected to the outlet of the air conditioning heat exchanger; the control system is used to control the operation of the entire device and can switch the connection between the low-temperature defrosting system, the high-temperature defrosting system, and the air conditioning heat exchanger, thereby conducting defrosting experiments or defrosting experiments on the air conditioning heat exchanger respectively.

[0007] The defrosting device of the present invention is a universal device for both defrosting and defrosting. The device integrates a low-temperature defrosting system and a high-temperature defrosting system into one unit. In use, by switching the low-temperature defrosting system or the high-temperature defrosting system to be connected to the air conditioner heat exchanger, a defrosting test or a defrosting test can be performed on the air conditioner heat exchanger respectively.

[0008] In this invention, the low-temperature frosting system includes a low-temperature ethylene glycol solution tank and a low-temperature tank outlet pipe, a low-temperature tank inlet pipe, a low-temperature tank circulation outlet pipe, and a low-temperature tank circulation inlet pipe connected to the low-temperature ethylene glycol solution tank. The low-temperature ethylene glycol solution tank contains ethylene glycol solution. A first solenoid valve is installed on the low-temperature tank outlet pipe, and a second solenoid valve is installed on the low-temperature tank inlet pipe. The outlet end of the low-temperature tank outlet pipe is connected to the inlet end of the liquid inlet pipe of an air conditioning heat exchanger, and the inlet end of the low-temperature tank inlet pipe is connected to the outlet end of the liquid outlet pipe of the air conditioning heat exchanger. The low-temperature tank circulation outlet pipe... Both the outlet pipe and the low-temperature chamber circulation inlet pipe are connected to the evaporator of the refrigerant system. The ethylene glycol solution from the low-temperature ethylene glycol solution tank exchanges heat with the evaporator after passing through the low-temperature chamber circulation outlet pipe, thereby lowering the solution temperature. Then, it flows back into the low-temperature ethylene glycol solution tank through the low-temperature chamber circulation inlet pipe. A first shut-off valve and a first circulation pump are installed on the low-temperature chamber circulation outlet pipe. The low-temperature ethylene glycol solution tank also has a built-in first electric heater. The first electric heater works together with the refrigerant system to control the solution temperature in the low-temperature ethylene glycol solution tank to reach the target temperature.

[0009] This low-temperature frosting system exchanges temperature between the ethylene glycol solution and the refrigerant circulation system, and also incorporates electric heating for auxiliary heating, which can ensure that the temperature of the ethylene glycol solution is precisely controlled at ±0.2℃.

[0010] In this invention, the high-temperature defrosting system includes a high-temperature ethylene glycol solution tank and a high-temperature tank outlet pipe and a high-temperature tank inlet pipe connected to the high-temperature ethylene glycol solution tank. The high-temperature ethylene glycol solution tank contains ethylene glycol solution. A third solenoid valve is installed on the high-temperature tank outlet pipe, and a fourth solenoid valve is installed on the high-temperature tank inlet pipe. The high-temperature tank outlet pipe and the low-temperature tank outlet pipe are connected in parallel. The outlet end of the high-temperature tank outlet pipe is connected to the inlet end of the liquid inlet pipe of the air conditioner heat exchanger. The high-temperature tank inlet pipe and the low-temperature tank inlet pipe are connected in parallel. The inlet end of the high-temperature tank inlet pipe is connected to the outlet end of the liquid outlet pipe of the air conditioner heat exchanger. The high-temperature ethylene glycol solution tank also has a built-in second electric heater to control the solution temperature in the high-temperature ethylene glycol solution tank to reach the target temperature.

[0011] The high-temperature defrosting system is electrically heated and controlled to achieve a temperature control accuracy of ±0.2℃.

[0012] In this invention, the air conditioning heat exchanger is connected to the test piece pipeline, which is connected to the inlet pipe and the outlet pipe respectively. A liquid supply pump is installed on the inlet pipe, a flow meter and a third shut-off valve are installed at the inlet end of the test piece pipeline, and a fourth shut-off valve is installed at the outlet end of the test piece pipeline.

[0013] As an improvement of the present invention: the test piece pipeline is further branched by a choke pipe. The inlet of the choke pipe is connected to the pipe section between the liquid supply pump and the flow meter, and the outlet of the choke pipe is connected to the pipe section located downstream of the fourth shut-off valve. A regulating valve is also provided on the choke pipe to control the flow rate through the choke pipe. When the refrigerant flow rate of the test piece cannot be reduced by adjusting the water pump, the flow rate of the choke pipe can be adjusted by the regulating valve to ensure that the flow rate meets the test requirements.

[0014] As an improvement of the present invention, the high-temperature ethylene glycol solution tank is further equipped with a heat exchange coil, which is connected to the low-temperature refrigerant side of the refrigerant system, so as to introduce the residual cold of the low-temperature refrigerant at the rear end of the evaporator of the refrigerant system into the high-temperature ethylene glycol solution tank and provide a cold source for the ethylene glycol solution in the tank.

[0015] This invention incorporates a heat exchange coil within a high-temperature ethylene glycol solution tank. The waste heat from the refrigerant exiting the evaporator of the refrigerant system is introduced into the tank through the heat exchange coil. This fully utilizes energy, saving energy and protecting the environment, while also ensuring sufficient superheat for the refrigerant system compressor return gas, thus protecting the compressor.

[0016] As an improvement of the present invention, the high-temperature ethylene glycol solution tank also includes a return pipe, the two ends of which are connected to the high-temperature ethylene glycol solution tank. A second shut-off valve and a second circulation pump are installed on the return pipe. The return pipe allows for circulation of the ethylene glycol solution, resulting in a more uniform solution temperature.

[0017] The defrosting device of this invention can replace the conventional method of building a complex and single refrigerant system for defrosting experiments on heat exchangers, enabling rapid and accurate defrosting experimental operations and procedures. This platform allows for defrosting experiments with different combinations of control parameters, greatly facilitating researchers in exploring optimal defrosting methods and approaches for heat exchangers from various perspectives. Furthermore, improvements to the device's control system allow users to obtain real-time parameters such as temperature, flow rate, flow resistance, and heat exchange capacity during experiments more intuitively, and automatically or manually output necessary reports during and after the experiment. Additionally, the device can be connected to an infrared high-definition visualization system for remote observation of the defrosting condition on the heat exchanger surface during experiments, with screenshots saved at any time. Attached Figure Description

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0019] Figure 1 This is a schematic diagram of the overall structure of the universal defrosting device used in the defrosting experiment of the air conditioner heat exchanger of the present invention.

[0020] Figure 2This is a schematic diagram of the low-temperature defrosting system in the universal defrosting device used for defrosting experiments of air conditioning heat exchangers according to the present invention.

[0021] Figure 3 This is a schematic diagram of the high-temperature defrosting system in the universal defrosting device used for defrosting experiments of air conditioning heat exchangers according to the present invention.

[0022] Explanation of reference numerals in the attached figures

[0023] 101. Low-temperature ethylene glycol solution tank; 102. Low-temperature tank outlet pipe; 103. First solenoid valve; 104. Low-temperature tank inlet pipe; 105. Second solenoid valve; 106. Low-temperature tank circulation outlet pipe; 107. First shut-off valve; 108. First circulation pump; 109. Low-temperature tank circulation inlet pipe; 110. First electric heater;

[0024] 201. High-temperature ethylene glycol solution tank; 202. High-temperature tank outlet pipe; 203. Third solenoid valve; 204. High-temperature tank inlet pipe; 205. Fourth solenoid valve; 206. Second electric heater; 207. Return pipe; 208. Second shut-off valve; 209. Second circulation pump;

[0025] 301. Inlet pipe; 302. Supply pump; 303. Flow meter; 304. Third shut-off valve; 305. Measuring element pipeline; 306. Fourth shut-off valve; 307. Cut-off pipe; 308. Regulating valve; 309. Outlet pipe;

[0026] 400. Refrigerant system; 401. Evaporator; 402. Heat exchange coil;

[0027] 500. Air conditioning heat exchanger. Detailed Implementation

[0028] like Figures 1 to 3 The universal defrosting device for air conditioning heat exchanger defrosting experiments shown includes a low-temperature defrosting system, a high-temperature defrosting system, and a control system. The low-temperature defrosting system and the high-temperature defrosting system are connected in parallel. Both the low-temperature defrosting system and the high-temperature defrosting system use ethylene glycol solution as a medium. The solution outlets of both the low-temperature defrosting system and the high-temperature defrosting system are connected to the inlet of the air conditioning heat exchanger 500, and the solution inlets of both the low-temperature defrosting system and the high-temperature defrosting system are connected to the outlet of the air conditioning heat exchanger 500. The control system is used to control the operation of the entire device and can switch the connection between the low-temperature defrosting system, the high-temperature defrosting system, and the air conditioning heat exchanger 500, thereby conducting defrosting experiments on the air conditioning heat exchanger 500 respectively.

[0029] In this embodiment, the low-temperature frosting system includes a low-temperature ethylene glycol solution tank 101 and a low-temperature tank outlet pipe 102, a low-temperature tank inlet pipe 104, a low-temperature tank circulation outlet pipe 106, and a low-temperature tank circulation inlet pipe 109 connected to the low-temperature ethylene glycol solution tank 101. The low-temperature ethylene glycol solution tank 101 contains ethylene glycol solution. A first solenoid valve 103 is installed on the low-temperature tank outlet pipe 102, and a second solenoid valve 105 is installed on the low-temperature tank inlet pipe 104. The outlet end of the low-temperature tank outlet pipe 102 is connected to air. The inlet end of the liquid inlet pipe 301 of the heat exchanger 500 is connected to the inlet end of the low temperature box inlet pipe 104, and the outlet end of the liquid outlet pipe 309 of the air conditioning heat exchanger 500 is connected to the outlet end of the low temperature box inlet pipe 106 and the low temperature box outlet pipe 109. The low temperature box circulation outlet pipe 106 and the low temperature box circulation inlet pipe 109 are both connected to the evaporator 401 of the refrigerant system 400. The refrigerant system 400 adopts the existing refrigerant system and includes the evaporator 401, compressor, condenser, heat exchange coil 402 and corresponding connecting pipes and control valves.

[0030] The ethylene glycol solution from the low-temperature ethylene glycol solution tank 101 exchanges heat with the evaporator 401 after passing through the low-temperature tank circulation outlet pipe 106. The evaporator 401 lowers the solution temperature, and then the solution flows back into the low-temperature ethylene glycol solution tank 101 through the low-temperature tank circulation inlet pipe 109. A first shut-off valve 107 and a first circulation pump 108 are installed on the low-temperature tank circulation outlet pipe 106. A first electric heater 110 is also built into the low-temperature ethylene glycol solution tank 101. The first electric heater 110 works together with the refrigerant system 400 to control the solution temperature in the low-temperature ethylene glycol solution tank 101 to reach the target temperature.

[0031] In this embodiment, the high-temperature defrosting system includes a high-temperature ethylene glycol solution tank 201 and a high-temperature tank outlet pipe 202 and a high-temperature tank inlet pipe 204 connected to the high-temperature ethylene glycol solution tank 201. The high-temperature ethylene glycol solution tank 201 contains ethylene glycol solution. A third solenoid valve 203 is installed on the high-temperature tank outlet pipe 202, and a fourth solenoid valve 205 is installed on the high-temperature tank inlet pipe 204. The high-temperature tank outlet pipe 202 and the low-temperature tank outlet pipe 102 are connected in parallel. The outlet end of the high-temperature tank outlet pipe 202 is connected to the inlet end of the liquid inlet pipe 301 of the air conditioning heat exchanger 500. The high-temperature tank inlet pipe 204 and the low-temperature tank inlet pipe 104 are connected in parallel. The inlet end of the high-temperature tank inlet pipe 204 is connected to the outlet end of the liquid outlet pipe 309 of the air conditioning heat exchanger 500. A second electric heater 206 is also built into the high-temperature ethylene glycol solution tank 201 to control the solution temperature in the high-temperature ethylene glycol solution tank 101 to reach the target temperature.

[0032] The air conditioning heat exchanger 500 is connected to the test pipe 305 as the test object. The test pipe 305 is connected to the inlet pipe 301 and the outlet pipe 309 respectively. The inlet pipe 301 is equipped with a liquid supply pump 302. The inlet end of the test pipe 305 is equipped with a flow meter 303 and a third shut-off valve 304 respectively. The outlet end of the test pipe 305 is equipped with a fourth shut-off valve 306.

[0033] In order to control the on / off state of the measuring element pipeline 305, a bypass pipe 307 is also branched off from the measuring element pipeline 305. The inlet of the bypass pipe 307 is connected to the pipeline section between the liquid supply pump 302 and the flow meter 303, and the outlet of the bypass pipe 307 is connected to the pipeline section located at the rear end of the fourth shut-off valve 306. A regulating valve 308 is also provided on the bypass pipe 307, and the excess flow of the measuring element pipeline 305 is controlled by controlling the regulating valve 308.

[0034] Two ethylene glycol solutions are connected through inlet and outlet solenoid valves, a variable frequency pump, and a flow meter in the pipeline. This allows for flexible and rapid switching between the high and low temperature solutions required for defrosting experiments, enabling precise and rapid control of the ethylene glycol solution flow rate with a flow accuracy of 1%.

[0035] In this embodiment, the high-temperature ethylene glycol solution tank 201 also has a built-in heat exchange coil 402, which is connected to the evaporator 401 of the refrigerant system 400. This coil further introduces the cooling energy contained in the low-temperature refrigerant exiting the evaporator 401 into the high-temperature ethylene glycol solution tank 201, fully utilizing energy to provide a cooling source for the tank. Together with the second electric heater 206, it controls the temperature of the ethylene glycol solution within the tank. By bypassing the high-temperature refrigerant system into the high-temperature ethylene glycol solution circulation system, energy conservation, emission reduction, and carbon neutrality are achieved.

[0036] The high-temperature ethylene glycol solution tank 201 also has a return pipe 207, the two ends of which are connected to the high-temperature ethylene glycol solution tank 201 respectively, and a second shut-off valve 208 and a second circulation pump 209 are installed on the return pipe 207.

[0037] In this embodiment, the defrosting device operates by controlling the actions of various pumps, valves, and components through a control system. The air conditioning heat exchanger 500, as the test object, undergoes defrosting or frost-forming experiments under the control of the control system. The control system accurately monitors and collects the entire online experimental process, outputting complete experimental data and reports, and allowing for real-time observation of the curve changes of various parameters during the experiment.

[0038] During the frosting experiment, the inlet and outlet solenoid valves connecting to the low-temperature ethylene glycol solution automatically open. Based on the set inlet temperature of the test piece, the low-temperature auxiliary refrigerant system and electric heating work together to control the temperature, ensuring the low-temperature ethylene glycol solution reaches the target temperature. After the system starts running, the supply pump adjusts the flow rate of the low-temperature ethylene glycol solution according to the pre-set frosting time and outlet temperature. As ambient air flows over the test piece, the frosting process is visualized.

[0039] By measuring the inlet and outlet temperatures and flow rates of the measured component, the change in its heat exchange capacity can be calculated; simultaneously, the inlet and outlet pressures of the measured component can be used to calculate its flow resistance.

[0040] During the defrosting experiment, the inlet and outlet solenoid valves connecting to the high-temperature ethylene glycol solution automatically open. Based on the set inlet temperature of the test piece, auxiliary electric heating controls the temperature, ensuring the high-temperature ethylene glycol solution reaches the target temperature. After the system starts running, the supply pump adjusts the flow rate of the high-temperature ethylene glycol solution according to the preset defrosting time and outlet temperature. Once the high-temperature ethylene glycol solution enters the test piece, the defrosting process becomes visible.

[0041] By measuring the inlet and outlet temperatures and flow rates of the measured component, the change in its heat exchange capacity can be calculated; simultaneously, the inlet and outlet pressures of the measured component can be used to calculate its flow resistance.

[0042] In this embodiment, the defrosting device can perform one or more functions in combination as needed:

[0043] 1) Frosting and defrosting times can be set;

[0044] 2) The evaporation temperature during frosting is controllable between -15°C and 0°C;

[0045] 3) The condensation temperature during defrosting is controllable from 10℃ to 40℃;

[0046] 4) Conditions for initiating defrosting: time, air resistance, heat exchanger outlet temperature, or any combination thereof;

[0047] 5) Defrosting termination conditions: time, heat exchanger outlet temperature, or any combination thereof.

[0048] In this embodiment, the control system includes a computer system, a digital instrument control system, and a PLC automation system. The computer system automatically sets test conditions, monitors the entire test process, collects all data from the test bench, performs stability checks and calculations on the operating conditions and data, outputs complete test data and reports, and allows for convenient manual control of the entire system's equipment actions. The digital control instruments primarily control the ethylene glycol solution temperature, the inlet and outlet temperatures and pressures of the test piece, the ethylene glycol supply flow rate, and the supply pump frequency through negative feedback. The PLC automation system automatically switches between test types, functions, and equipment startup, output changes, and shutdown based on set conditions and instrument feedback parameters.

[0049] The above embodiments of the present invention are not intended to limit the scope of protection of the present invention. The implementation of the present invention is not limited thereto. All other modifications, substitutions or alterations made to the above structure of the present invention based on the above content of the present invention, in accordance with ordinary technical knowledge and common practice in the field, without departing from the basic technical idea of ​​the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A general defrosting device for air conditioner heat exchanger defrosting experiment, characterized in that: The device includes a low-temperature frosting system, a high-temperature defrosting system, and a control system. The low-temperature frosting system and the high-temperature defrosting system are connected in parallel. Both the low-temperature frosting system and the high-temperature defrosting system use ethylene glycol solution as a medium. The solution outlets of the low-temperature frosting system and the high-temperature defrosting system are connected to the inlet of the air conditioning heat exchanger (500), and the solution inlet of the low-temperature frosting system and the high-temperature defrosting system are connected to the outlet of the air conditioning heat exchanger (500). The control system is used to control the operation of the entire device and can switch the connection between the low-temperature frosting system, the high-temperature defrosting system, and the air conditioning heat exchanger (500), so as to conduct frosting experiments or defrosting experiments on the air conditioning heat exchanger (500) respectively. The low-temperature frosting system includes a low-temperature ethylene glycol solution tank (101) and a low-temperature tank outlet pipe (102), a low-temperature tank inlet pipe (104), a low-temperature tank circulation outlet pipe (106), and a low-temperature tank circulation inlet pipe (109) connected to the low-temperature ethylene glycol solution tank (101). The low-temperature ethylene glycol solution tank (101) contains ethylene glycol solution. A first solenoid valve (103) is installed on the low-temperature tank outlet pipe (102), and a second solenoid valve (105) is installed on the low-temperature tank inlet pipe (104). The outlet end of the low-temperature tank outlet pipe (102) is connected to the inlet end of the liquid inlet pipe (301) of the air conditioning heat exchanger (500), and the inlet end of the low-temperature tank inlet pipe (104) is connected to the outlet end of the liquid outlet pipe (309) of the air conditioning heat exchanger (500). The low-temperature tank circulation outlet pipe (106) is connected to the inlet end of the outlet pipe (309) of the air conditioning heat exchanger (500). 6) Both the low-temperature chamber circulation inlet pipe (109) and the low-temperature chamber circulation outlet pipe (106) are connected to the evaporator (401) of the refrigerant system (400). The ethylene glycol solution from the low-temperature ethylene glycol solution tank (101) exchanges heat with the evaporator (401) after passing through the low-temperature chamber circulation outlet pipe (106). The evaporator (401) lowers the solution temperature, and then flows back into the low-temperature ethylene glycol solution tank (101) through the low-temperature chamber circulation inlet pipe (109). The low-temperature chamber circulation outlet pipe (106) is equipped with a first shut-off valve (107) and a first circulation pump (108). The low-temperature ethylene glycol solution tank (101) is also equipped with a first electric heater (110). The first electric heater (110) works together with the refrigerant system (400) to control the solution temperature in the low-temperature ethylene glycol solution tank (101) to reach the target temperature. The high-temperature defrosting system includes a high-temperature ethylene glycol solution tank (201) and a high-temperature tank outlet pipe (202) and a high-temperature tank inlet pipe (204) connected to the high-temperature ethylene glycol solution tank (201). The high-temperature ethylene glycol solution tank (201) contains ethylene glycol solution. A third solenoid valve (203) is installed on the high-temperature tank outlet pipe (202), and a fourth solenoid valve (205) is installed on the high-temperature tank inlet pipe (204). The high-temperature tank outlet pipe (202) and the low-temperature tank outlet pipe (102) are connected in parallel. The outlet end of the outlet pipe (202) is connected to the inlet end of the liquid inlet pipe (301) of the air conditioning heat exchanger (500). The inlet pipe (204) of the high temperature chamber is connected in parallel with the inlet pipe (104) of the low temperature chamber. The inlet end of the high temperature chamber inlet pipe (204) is connected to the outlet end of the liquid outlet pipe (309) of the air conditioning heat exchanger (500). The high temperature ethylene glycol solution tank (201) is also equipped with a second electric heater (206) to control the solution temperature in the high temperature ethylene glycol solution tank (201) to reach the target temperature.

2. The general defrosting device for defrosting experiment of an air conditioner heat exchanger according to claim 1, characterized in that: The air conditioning heat exchanger (500) is connected to the measuring pipe (305). The measuring pipe (305) is connected to the inlet pipe (301) and the outlet pipe (309) respectively. A liquid supply pump (302) is installed on the inlet pipe (301). A flow meter (303) and a third shut-off valve (304) are installed at the inlet end of the measuring pipe (305) respectively. A fourth shut-off valve (306) is installed at the outlet end of the measuring pipe (305).

3. The general defrosting device for defrosting experiment of an air conditioner heat exchanger according to claim 2, characterized in that: The measuring device pipeline (305) is also branched by a choke pipe (307). The inlet of the choke pipe (307) is connected to the pipe section between the liquid supply pump (302) and the flow meter (303). The outlet of the choke pipe (307) is connected to the pipe section located at the rear end of the fourth shut-off valve (306). A regulating valve (308) is also provided on the choke pipe (307). The excess flow of the measuring device pipeline (305) is controlled by controlling the regulating valve (308).

4. The universal defrosting device for defrosting experiments of air conditioning heat exchangers according to claim 1, characterized in that: The high-temperature ethylene glycol solution tank (201) is also equipped with a heat exchange coil (402), which is connected to the evaporator (401) of the refrigerant system (400). The heat exchange coil (402) further introduces the cold energy contained in the low-temperature refrigerant coming out of the evaporator (401) into the high-temperature ethylene glycol solution tank (201) to provide a cold source for the high-temperature ethylene glycol solution tank (201) and, together with the second electric heater (206), controls the temperature of the ethylene glycol solution in the tank.

5. The universal defrosting device for defrosting experiments of air conditioning heat exchangers according to claim 1, characterized in that: The high-temperature ethylene glycol solution tank (201) also has a return pipe (207), the two ends of which are connected to the high-temperature ethylene glycol solution tank (201) respectively. A second shut-off valve (208) and a second circulation pump (209) are installed on the return pipe (207).

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