Forced convection type refrigerator heat exchanger performance measurement and control platform

Abstract

The invention discloses a refrigerator heat exchanger performance measurement and control platform in a forced convection mode. The refrigerator heat exchanger performance measurement and control platform comprises an air pretreatment device, a measured piece box, an air volume measurement device, a frequency conversion fan, a hot water system, a cold water system and a measurement and control system. One end of the air pretreatment device is a fresh air inlet, and the other end is connected with an air inlet of the tested piece box; the air outlet of the measured piece box is connected with the air inlet of the air volume measuring device, and the air outlet of the air volume measuring device is connected with the frequency conversion fan. A surface air cooler connected with a cold water system in the air pretreatment device can provide stable low-temperature air, external temperature interference is reduced, and it is ensured that test conditions are stable and reliable; the measured piece box and the air volume measuring device are effectively matched, so that the air flowing state is accurately monitored; the hot water system meets hot water requirements of different temperature flows; the variable-frequency fan flexibly adjusts the air flow; all the parts are electrically connected with the measurement and control system, intelligent control is achieved, and the accuracy, comprehensiveness and testing efficiency of performance testing of the refrigerator heat exchanger are improved.

Description

Technical Field

[0001] The present invention relates to the field of detection technology, and particularly to a performance measurement and control platform for a refrigerator heat exchanger in a forced convection manner. Background Art

[0002] Since the advent of refrigerators, the early user requirements mainly focused on whether the device could achieve the basic refrigeration function, and the attention to its specific performance indicators was relatively low. However, with the progress of society and the development of technology, consumers' requirements for refrigerator performance have gradually increased. Especially in the context of the country's advocacy of energy conservation and emission reduction, the overall efficiency and energy use of refrigerators have become the focus of people's attention. Therefore, it has become particularly crucial to develop a test system that can accurately evaluate the performance of refrigerator heat exchangers.

[0003] As one of the core components of the refrigeration system, the heat exchange efficiency of the refrigerator heat exchanger directly affects the operation effect of the entire refrigerator system. Although there are currently various test platforms for measuring the performance of heat exchangers on the market, and most of them use the refrigerant liquid flow method to determine the refrigeration capacity of the heat exchanger - that is, under standard operating conditions, by measuring the change in the specific enthalpy of the refrigerant entering and leaving the heat exchanger under test and the mass flow rate of the refrigerant flowing through the heat exchanger, the standard refrigeration capacity of the heat exchanger is calculated. However, for the evaporator and condenser in the refrigerator, due to the relatively small heat exchange amount involved, it is still a challenge to accurately measure the performance of these components. Summary of the Invention

[0004] The purpose of the present invention is to provide a performance measurement and control platform for a refrigerator heat exchanger in a forced convection manner, which can create various temperature and air volume conditions to simulate different test environments, is suitable for the performance evaluation of refrigerator heat exchangers, and thus provides reliable data support for improving the heat exchange performance.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] Performance measurement and control platform for a refrigerator heat exchanger in forced convection mode, comprising an air pretreatment device, a test piece box for placing the test piece to be measured, an air volume measurement device, a variable-frequency fan, a hot water system, a cold water system and a measurement and control system; the air pretreatment device includes a section of pretreatment air duct, the inlet of the pretreatment air duct is a fresh air inlet, and at the fresh air inlet, there is a surface cooler connected to the cold water system for obtaining flowing air with a temperature lower than the ambient temperature, and the outlet of the pretreatment air duct is connected to the air inlet of the test piece box; the test piece box includes a section of test piece box duct, the air inlet of the test piece box duct is connected to the outlet of the pretreatment air duct, and the outlet is connected to the air inlet of the air volume measurement device; the air volume measurement device includes a section of air volume measurement channel, the air inlet of the air volume measurement channel is connected to the outlet of the test piece box, and the outlet is connected to the variable-frequency fan, and the variable-frequency fan communicates with the external environment through an air outlet; the cold water system provides circulating cold water with stable temperature and flow for the surface cooler in the air pretreatment device; the hot water system provides circulating hot water with different temperatures and different flows for the test piece in the test piece box; the variable-frequency fan extracts air from the outlet of the air volume measurement device and blows it into the external environment; the air pretreatment device, the air volume measurement device, the variable-frequency fan, the cold and hot water systems are respectively electrically connected to the measurement and control system, and the air pretreatment device, the variable-frequency fan and the cold and hot water systems jointly provide different working conditions for the performance measurement and control platform of the refrigerator heat exchanger.

[0007] Furthermore, in the pretreatment air duct, starting from the fresh air inlet, there are sequentially arranged an air electric heater, a first flow equalizing grid, a first platinum resistor and a relative humidity sensor; the air electric heater and the first platinum resistor are electrically connected to the first controller of the measurement and control system, the input end and the output end of the first controller are respectively electrically connected to the first platinum resistor and the first power regulator, and the first controller of the measurement and control system obtains the value of the first platinum resistor, compares it with the set value, and then adjusts the first power regulator according to the result to control the air electric heater to adjust the inlet air temperature of the test piece box.

[0008] Furthermore, in the test piece box duct, starting from the air inlet, there are sequentially arranged a first static pressure ring, an inlet air thermocouple matrix, the test piece, a second flow equalizing grid, an outlet air thermocouple matrix and a second static pressure ring; the first static pressure ring and the second static pressure ring are connected by pipelines to a first differential pressure transmitter; the measurement and control system is electrically connected to the first differential pressure transmitter to obtain the air resistance of the test piece, and the measurement and control system obtains the temperatures before and after flowing through the test piece through the inlet air thermocouple matrix and the outlet air thermocouple matrix.

[0009] Further, the air volume measurement channel is sequentially provided with a second platinum resistor, a third flow equalizing grid, a third static pressure ring, a nozzle device, a fourth static pressure ring, and a fourth flow equalizing grid starting from the air inlet; the third static pressure ring and the fourth static pressure ring are connected to the second differential pressure transmitter through pipelines, and the third static pressure ring is also connected to the pressure sensor through a pipeline. The pressure sensor and the second platinum resistor are electrically connected to the measurement and control system; the input end and the output end of the second controller are electrically connected to the second differential pressure transmitter and the first frequency converter respectively, and the first frequency converter is electrically connected to the variable frequency fan. The second controller of the measurement and control system is electrically connected to the second differential pressure transmitter to obtain the pressure difference before and after the nozzle device and compare it with the set value, and then adjust the first frequency converter according to the result to control the variable frequency fan to change the air volume.

[0010] Further, the chilled water system is provided with a chiller that can provide chilled water with a stable temperature, and the chiller is connected to the surface cooler through a pipeline.

[0011] Further, the hot water system is provided with a hot water tank. A water pump, a water-side electric heater, a flow meter, a pressure measuring point at the inlet of the measured component, and a third platinum resistor are sequentially arranged at the outlet of the hot water tank, and a fourth platinum resistor and a pressure measuring point at the outlet of the measured component are sequentially arranged at the inlet of the hot water tank; the water-side electric heater and the third platinum resistor are electrically connected to the third controller of the measurement and control system. The input end and the output end of the third controller are electrically connected to the third platinum resistor and the second power regulator respectively; the third controller of the measurement and control system obtains the value of the third platinum resistor and compares it with the set value, and then adjusts the second power regulator according to the result to control the water-side electric heater; the flow meter and the water pump are electrically connected to the fourth controller of the measurement and control system. The input end and the output end of the fourth controller are electrically connected to the flow meter and the second frequency converter respectively; the fourth controller of the measurement and control system obtains the value of the flow meter and compares it with the set value, and then adjusts the second frequency converter according to the result to control the water pump to change the hot water flow; the pressure measuring point at the inlet of the measured component and the pressure measuring point at the outlet of the measured component are connected to the third differential pressure transmitter through pipelines to obtain the water resistance of the measured component, and the fourth platinum resistor is electrically connected to the measurement and control system.

[0012] Further, water inlet holes and water outlet holes for corresponding connection of the measured component and the inlet and outlet of the hot water tank are opened on the side surface of the measured component box.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] Through the organic combination of an air pretreatment device, a test piece box, an air volume measurement device, a variable-frequency fan, a cold and hot water system, and a measurement and control system, the present invention can accurately simulate various actual working conditions to achieve high-precision testing of the performance of refrigerator heat exchangers. The surface cooler connected to the cold water system in the air pretreatment device can provide stable low-temperature air, reduce the interference of the external temperature, ensure the stability and reliability of the test conditions, and create a good start for accurate measurement; the test piece box and the air volume measurement device cooperate effectively to achieve accurate monitoring of the air flow state; the hot water system meets the hot water requirements of different temperatures and flows; the variable-frequency fan flexibly adjusts the air flow; each part is electrically connected to the measurement and control system to achieve intelligent control, and overall greatly improves the accuracy, comprehensiveness, and test efficiency of the performance test of refrigerator heat exchangers.

[0015] By setting a surface cooler connected to the cold water system, the present invention can obtain flowing air with a temperature lower than the ambient temperature, ensuring that the air entering the subsequent test links has a stable low-temperature starting point. This design not only provides a basis for accurately controlling the final air temperature but also reduces the influence of external ambient temperature fluctuations on the test conditions, ensuring the consistency and controllability of the air temperature during the test, thereby significantly improving the reliability and accuracy of the test results. In addition, the presence of the surface cooler expands the range of test conditions, enabling the measurement and control platform to simulate various temperature situations that may be encountered in the actual use environment, especially those far lower than the ambient temperature. This helps to more comprehensively evaluate the performance of the refrigerator heat exchanger under different working conditions and ensures the accuracy and practicality of the test data.

[0016] Furthermore, the present invention provides stable test conditions for the test piece by setting four controllers, each of which is responsible for the adjustment of different parts. The first controller obtains the resistance value of the first platinum resistor, compares it with the set value, and adjusts the first power regulator according to the signal output to control the air electric heating device, thereby providing flowing air with a stable set temperature. The second controller obtains the differential pressure value through the second differential pressure transmitter, compares it with the set value, and adjusts the first frequency converter according to the signal to control the variable-frequency fan to provide flowing air with a stable air volume. The third controller obtains the resistance value of the third platinum resistor, compares it with the set value, and outputs a signal to adjust the second power regulator to control the water-side electric heating device to ensure the supply of a circulating water flow with a stable set temperature. The fourth controller obtains the water flow data of the flowmeter, compares it with the set value, and adjusts the second frequency converter according to the signal to control the water pump to provide a circulating water flow with a stable flow rate. Through the collaborative work of these multiple controllers, the present invention can provide different working conditions for the measurement of the test piece.

[0017] Furthermore, the present invention obtains key data through multiple sensors and controllers to accurately evaluate the heat exchange performance. Specifically, the air temperature flowing into the box of the device under test is obtained through the inlet air thermocouple matrix, and the air temperature flowing through the device under test is obtained through the outlet air thermocouple matrix; the air flow rate is calculated based on the values obtained by the nozzle device and the second differential pressure gauge, thereby obtaining the enthalpy value of the air. At the same time, the third controller measures the water flow temperature flowing into the device under test by obtaining the resistance value of the third platinum resistor; measures the water flow temperature flowing out of the device under test by obtaining the resistance value of the fourth platinum resistor; in addition, the water pressure difference between the water flowing into and out of the device under test is obtained through the third differential pressure transmitter. Finally, the fourth controller measures the flow rate value through the flowmeter. The comprehensive utilization of these data provides a reliable basis for improving the heat exchange performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of the present invention;

[0019] Figure 2 is a schematic control diagram of the wind tunnel system of the present invention;

[0020] Figure 3 is a schematic control diagram of the hot water system of the present invention;

[0021] Figure 4 is a schematic diagram of data acquisition and control of the performance parameters of the heat exchanger of the present invention;

[0022] In the figure: 1 - air pretreatment device; 2 - pretreatment air duct; 3 - box of the device under test; 4 - air duct of the box of the device under test; 5 - air flow rate measuring device; 6 - air flow rate measuring channel; 7 - surface cooler; 8 - air electric heater; 9 - first flow equalizing grid; 10 - first platinum resistor; 11 - relative humidity sensor; 12 - first static pressure ring; 13 - inlet air thermocouple matrix; 14 - device under test; 15 - second flow equalizing grid; 16 - outlet air thermocouple matrix; 17 - second static pressure ring; 18 - second platinum resistor; 19 - third flow equalizing grid; 20 - third static pressure ring; 21 - nozzle device; 22 - fourth static pressure ring; 23 - fourth flow equalizing grid; 24 - variable frequency fan; 25 - chiller; 26 - hot water tank; 27 - water pump; 28 - water side electric heater; 29 - flowmeter; 30 - pressure measuring point of the water inlet of the device under test; 31 - third platinum resistor; 32 - fourth platinum resistor; 33 - pressure measuring point of the water outlet of the device under test; fresh air inlet 34; 35 - air outlet; 36 - first controller; 37 - first power regulator; 38 -; 39 - second differential pressure transmitter; 40 - second controller; 41 - first frequency converter; 43 - third controller; 44 - second power regulator; 45 - fourth controller; 46 - second frequency converter; 47 - pressure sensor. DETAILED DESCRIPTION OF THE INVENTION

[0023] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] As Figure 1 , 2 , 3, and 4 show, the performance measurement and control platform for the refrigerator heat exchanger in the forced convection mode described in this embodiment includes an air pretreatment device 1, a test piece box 3 for placing the test piece 14, an air volume measurement device 5, a variable frequency fan 24, a hot water system, a cold water system, and a measurement and control system. The air pretreatment device 1, the test piece box 3, the air volume measurement device 5, and the variable frequency fan 24 are respectively supported by brackets. The measurement and control system mainly consists of devices such as a PLC, a data collector, an industrial control computer, and a printer. The operator can input the set values of the inlet air temperature, the test air volume, the inlet water temperature of the test piece, and the water flow rate of the test piece. The industrial control computer reads the data obtained by the measurement and control system and can perform operations such as viewing, saving, extracting, and printing.

[0025] The air pretreatment device 1 includes a section of pretreatment air duct 2 with an inlet at the fresh air inlet 34 and an outlet connected to the inlet of the test piece box 3; the test piece box 3 includes a section of test piece box duct 4, the inlet of the test piece box duct 4 is connected to the outlet of the pretreatment air duct 2, and the outlet is connected to the inlet of the air volume measurement device 5; the air volume measurement device 5 includes a section of air volume measurement channel 6, the inlet of the air volume measurement channel 6 is connected to the outlet of the test piece box 3, and the outlet is connected to the variable frequency fan 24, and the variable frequency fan 24 is connected to the external environment through the air outlet 35. The air pretreatment device 1, the air volume measurement device 5, the variable frequency fan 24, and the cold and hot water systems are respectively electrically connected to the measurement and control system. The air pretreatment device 1, the variable frequency fan 24, and the cold and hot water systems jointly provide different working conditions for the performance measurement and control platform of the refrigerator heat exchanger.

[0026] In the pretreatment air duct 2, a surface cooler 7, an air electric heater 8, a first uniform flow grid 9, a first platinum resistor 10, and a relative humidity sensor 11 are sequentially arranged starting from the inlet. The surface cooler 7 is connected to the chiller 25 provided in the cold water system through a pipeline to provide stable cooling capacity for the air pretreatment device 1; the air electric heater 8 and the first platinum resistor 10 are electrically connected to the first controller 36 of the measurement and control system. The input end and the output end of the first controller 36 are respectively electrically connected to the first platinum resistor 10 and the first power regulator 37. The first controller 36 of the measurement and control system obtains the value of the first platinum resistor 9, compares it with the set value, and then outputs a signal according to the result to adjust the first power regulator 37 to control the air electric heater 8 to adjust the inlet air temperature of the test piece box 3.

[0027] After the air enters from the fresh air inlet 34, it is first cooled to a temperature lower than the ambient temperature by the surface cooler 7. Subsequently, the air is accurately heated by the air electric heater 8 to reach the set test temperature. The heated air passes through the first flow-equalizing network 9, which rectifies the air into an airflow with uniform speed and consistent direction to ensure the accuracy of subsequent measurements. The rectified air flows through the first platinum resistor 10 and the relative humidity sensor 11. The relative humidity sensor 11 is used to accurately measure the air temperature and humidity. The resistance value of the first platinum resistor 10 corresponds to its temperature, so the measurement and control system can determine the air temperature by obtaining the resistance value. Finally, the air processed by the flow-equalizing process enters the inside of the test piece box 3 from the pre-treated air outlet to ensure that the air flows through the outer surface of the test piece 14 at a uniform speed and temperature, which is conducive to subsequent measurements.

[0028] The air duct 4 of the test piece box is provided with the first static pressure ring 12, the air inlet thermocouple matrix 13, the test piece 14, the second flow equalizing network 15, the air outlet thermocouple matrix 16 and the second static pressure ring 17 in sequence starting from the air inlet. The heat exchanger test piece 14 is placed in the middle of the test piece box 3, and the gap between the test piece 14 and the test piece box 3 is tightly filled with thermal insulation material. The side of the test piece box 4 is provided with a water inlet hole and a water outlet hole for corresponding connection of the test piece 14 and the water inlet and outlet of the hot water tank 26. The first static pressure ring 12 and the second static pressure ring 17 are connected to the first differential pressure transmitter 38 by pipeline, and the measurement and control system is electrically connected to the first differential pressure transmitter 38 to obtain the wind resistance of the test piece 14. The measurement and control system obtains the temperature before and after the flow through the test piece 14 through the air inlet thermocouple matrix 13 and the air outlet thermocouple matrix 16.

[0029] The air volume measurement channel 6 is sequentially provided with the second platinum resistor 18, the third flow balancing net 19, the third static pressure ring 20, the nozzle device 21, the fourth static pressure ring 22 and the fourth flow balancing net 23 starting from the air inlet. The third static pressure ring 20 and the fourth static pressure ring 22 are connected to the second differential pressure transmitter 39 through a pipeline. The third static pressure ring 20 is also connected to the pressure sensor 47 through a pipeline. The pressure sensor 47 and the second platinum resistor 18 are electrically connected to the measurement and control system. The input and output ends of the second controller 40 are electrically connected to the second differential pressure transmitter 39 and the first frequency converter 41 respectively. The first frequency converter 41 is electrically connected to the variable frequency fan 24. The second controller 40 of the measurement and control system is electrically connected to the second differential pressure transmitter 39 to obtain the comparison between the pressure difference before and after the nozzle device 21 and the setting, and then adjust the first frequency converter 41 according to the result output signal to control the variable frequency fan 24 to change the air volume.

[0030] The air coming out of the DUT box 3 enters through the air volume measurement air duct and undergoes temperature measurement through the second platinum resistor 18; the measured air then passes through the third flow equalizing grid 19, which rectifies the air flow into a state of uniform velocity and consistent direction. This step ensures that the air flow has stable characteristics when entering the differential pressure measurement device, thereby improving the measurement accuracy of the air. The rectified air flows through the nozzle device 21. The nozzle device is used in conjunction with the second differential pressure transmitter 39 to calculate the air flow rate by measuring the pressure difference before and after the air passes through the nozzle; finally, the measured air flows out from the outlet of the air volume measurement channel 6.

[0031] The hot water system is equipped with a hot water tank 26. A water pump 27, a water-side electric heater 28, a flow meter 29, a pressure measurement point 30 at the water inlet of the DUT, and a third platinum resistor 31 are sequentially arranged at the water outlet of the hot water tank 26. A fourth platinum resistor 32 and a pressure measurement point 33 at the water outlet of the DUT are sequentially arranged at the water inlet of the hot water tank 26. The water-side electric heater 28 and the third platinum resistor 31 are electrically connected to the third controller 43 of the measurement and control system. The input and output ends of the third controller 43 are respectively electrically connected to the third platinum resistor 31 and the second power regulator 44; the third controller 43 of the measurement and control system obtains the value of the third platinum resistor 31, compares it with the set value, and then outputs a signal according to the result to adjust the second power regulator 44 to control the water-side electric heater 28. The flow meter 29 and the water pump 27 are electrically connected to the fourth controller 45 of the measurement and control system. The input and output ends of the fourth controller 45 are respectively electrically connected to the flow meter 29 and the second frequency converter 46; the fourth controller 45 of the measurement and control system obtains the value of the flow meter 29, compares it with the set value, and then outputs a signal according to the result to adjust the second frequency converter 46 to control the water pump 27 to change the hot water flow rate; the pressure measurement point 30 at the water inlet of the DUT and the pressure measurement point 33 at the water outlet of the DUT are connected by a pipeline to the third differential pressure transmitter 42 to obtain the water resistance of the DUT 14; the fourth platinum resistor 32 is electrically connected to the measurement and control system.

Claims

1. The forced convection refrigerator heat exchanger performance measurement and control platform is characterized by: It comprises an air pre-treatment device (1), a test piece box (3) for placing a test piece (14), an air volume measuring device (5), a variable frequency fan (24), a hot water system, a cold water system and a measurement and control system; The air pretreatment device (1) comprises a pretreatment air duct (2), the inlet of the pretreatment air duct (2) is a fresh air inlet (34), a surface cooler (7) connected to a cold water system for obtaining flowing air with a temperature lower than that of the ambient temperature is arranged at the fresh air inlet (34), and the outlet of the pretreatment air duct (2) is connected to the air inlet of the test piece box (3); The test piece box (3) comprises a section of the test piece box air duct (4), the air inlet of the test piece box air duct (4) is connected to the outlet of the pre-processed air duct (2), and the air outlet is connected to the air inlet of the air volume measuring device (5); The air volume measuring device (5) comprises an air volume measuring channel (6), the air inlet of the air volume measuring channel (6) is connected to the air outlet of the measured component box (3), the air outlet is connected to the variable frequency fan (24), and the variable frequency fan (24) is connected to the external environment through the air outlet (35); The cold water system provides circulating cold water with stable temperature and flow rate to the surface cooler (7) in the air pretreatment device (1); the hot water system provides circulating hot water with different temperatures and flow rates to the test object (14) in the test box (3); the variable frequency fan (24) draws air from the outlet of the air volume measuring device (5) and blows it to the external environment; The air pretreatment device (1), the air volume measurement device (5), the variable frequency fan (24), and the cold and hot water systems are electrically connected to the measurement and control system respectively. The air pretreatment device (1), the variable frequency fan (24), and the cold and hot water systems jointly provide different working conditions for the refrigerator heat exchanger performance measurement and control platform.

2. The forced convection refrigerator heat exchanger performance measurement and control platform according to claim 1, characterized in that: The pre-processed air duct (2) is also provided with an air electric heater (8), a first current balancing network (9), a first platinum resistor (10) and a relative humidity sensor (11) in sequence starting from the fresh air inlet (34); the air electric heater (8) and the first platinum resistor (10) are electrically connected to a first controller (36) of a measurement and control system; the input end and the output end of the first controller (36) are electrically connected to the first platinum resistor (10) and the first power regulator (37) respectively; the first controller (36) of the measurement and control system obtains the value of the first platinum resistor (9) and compares it with a set value, and then adjusts the first power regulator (37) according to the result output signal to control the air electric heater (8) to adjust the air inlet temperature of the measured component box (3).

3. The forced convection refrigerator heat exchanger performance measurement and control platform according to claim 1, characterized in that: The test piece box air duct (4) is provided with a first static pressure ring (12), an air inlet thermocouple matrix (13), a test piece (14), a second flow balancing network (15), an air outlet thermocouple matrix (16) and a second static pressure ring (17) in sequence from the air inlet; the first static pressure ring (12) and the second static pressure ring (17) are connected to a first differential pressure transmitter (38) by pipeline; the measurement and control system is electrically connected to the first differential pressure transmitter (38) to obtain the wind resistance of the test piece (14), and the measurement and control system obtains the temperature before and after the air flows through the test piece (14) through the air inlet thermocouple matrix (13) and the air outlet thermocouple matrix (16).

4. The forced convection refrigerator heat exchanger performance measurement and control platform according to claim 1, characterized in that: The air volume measurement channel (6) is provided with a second platinum resistor (18), a third flow balancing network (19), a third static pressure ring (20), a nozzle device (21), a fourth static pressure ring (22) and a fourth flow balancing network (23) in sequence from the air inlet; the third static pressure ring (20) and the fourth static pressure ring (22) are connected to the second differential pressure transmitter (39) via a pipeline, the third static pressure ring (22) is also connected to the pressure sensor (47) via a pipeline, and the pressure sensor (47) and the second platinum resistor (18) are electrically connected to the measurement and control system; The input end and the output end of the second controller (40) are electrically connected to the second differential pressure transmitter (39) and the first frequency converter (41) respectively, and the first frequency converter (41) is electrically connected to the variable frequency fan (24). The second controller (40) of the measurement and control system is electrically connected to the second differential pressure transmitter (39) to obtain the pressure difference before and after the nozzle device (21) and compare it with the setting, and then adjust the first frequency converter (41) according to the result output signal to control the variable frequency fan (24) to change the air volume.

5. The forced convection refrigerator heat exchanger performance measurement and control platform according to claim 1, characterized in that: The cold water system is provided with a water chiller (25) capable of providing cold water at a stable temperature, and the water chiller (25) is connected to the surface cooler (7) through a pipeline.

6. The forced convection refrigerator heat exchanger performance measurement and control platform according to claim 1, characterized in that: The hot water system is provided with a hot water tank (26), the water outlet of the hot water tank (26) is provided with a water pump (27), a water side electric heater (28), a flow meter (29), a water inlet pressure measuring point (30) of the measured object and a third platinum resistor (31) in sequence, and the water inlet of the hot water tank (26) is provided with a fourth platinum resistor (32) and a water outlet pressure measuring point (33) of the measured object in sequence; The water-side electric heater (28) and the third platinum resistor (31) are electrically connected to a third controller (43) of the measurement and control system, and the input end and the output end of the third controller (43) are electrically connected to the third platinum resistor (31) and the second power regulator (44) respectively; the third controller (43) of the measurement and control system obtains the value of the third platinum resistor (31) and compares it with the set value, and then adjusts the second power regulator (44) to control the water-side electric heater (28) according to the result output signal; The flow meter (29) and the water pump (27) are electrically connected to a fourth controller (45) of the measurement and control system, and the input end and the output end of the fourth controller (45) are electrically connected to the flow meter (29) and the second frequency converter (46) respectively; the fourth controller (45) of the measurement and control system obtains the value of the flow meter (29) and compares it with the set value, and then adjusts the second frequency converter (46) to control the water pump (27) according to the result output signal to change the hot water flow rate; the water inlet pressure measuring point (30) of the measured object and the water outlet pressure measuring point (33) of the measured object are connected to the third differential pressure transmitter (42) through a pipeline to obtain the water resistance of the measured object (14), and the fourth platinum resistor (32) is electrically connected to the measurement and control system.

7. The forced convection refrigerator heat exchanger performance measurement and control platform according to claim 6, characterized in that: A water inlet hole and a water outlet hole are provided on the side of the test piece box (3) for corresponding connection with the water inlet and outlet of the test piece (14) and the hot water tank (26).

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