A simulation test method based on the condensation heat transfer law of refrigerant in a calorimeter

Abstract

The present application belongs to the technical field of refrigeration compressor testing, and particularly relates to a simulation testing method for condensation heat transfer law of refrigerant in a calorimeter. The present application comprises the following steps: S1. performing a testing of calibrating the heat leakage of a calorimeter simulation device; S2. performing a testing of heat leakage heat transfer of the calorimeter simulation device under a set working condition; and S3. calculating the heat leakage ratio. The present application can realize accurate measurement of key parameter values such as heat exchange capacity of a cold coil, heat leakage of a calorimeter, heat leakage coefficient of a calorimeter, and heat leakage ratio of a calorimeter, and finally provides a basic guarantee for improvement of the testing precision of the overall performance of a compressor.

Description

Technical Field

[0001] This invention belongs to the field of refrigeration compressor testing technology, specifically relating to a simulation test method based on the condensation heat transfer law of refrigerant in a calorimeter. Background Technology

[0002] Currently, the second refrigerant calorimeter method is the most widely used performance testing method for volumetric refrigerant compressors. This method mainly uses the heat generated by an electric heater to balance the compressor's cooling capacity after the test condition, and then corrects the measured electric heating amount according to the corresponding method to obtain the compressor's cooling capacity under the test condition. In the process of testing the compressor's cooling capacity, the existing standards for calibrating the heat leakage and heat leakage coefficient of the calorimeter are not perfect, resulting in many unstable factors such as different measurement methods, different instrument accuracy, environmental fluctuations and deviations, and interference factors, which will cause many uncertainties in the measured parameter values. At the same time, because this method contains a second refrigerant, there are problems such as high operating pressure, high pressure resistance of the container, large cylinder mass and large heat storage, and large temperature inertia. In addition, when the evaporation temperature is low, the cooling capacity of the compressor under test is small, but the heat leakage is larger, which has a significant impact on the stability of the system and the accuracy of the cooling capacity measurement of the tested compressor. This also makes the accurate measurement of parameters such as actual heat leakage and heat leakage coefficient a persistent problem that needs to be improved. However, if the accuracy of the measured parameter values, especially the key parameter values, decreases, the uncertainty of heat leakage correction will inevitably increase, which will naturally hinder the rapid and accurate measurement of the compressor's cooling capacity. Therefore, this issue urgently needs to be addressed. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a simulation test method for the condensation heat transfer law of refrigerant in a calorimeter. This method can accurately measure key parameters such as the heat exchange of the cold coil, the heat loss of the calorimeter, the heat loss coefficient of the calorimeter, and even the heat loss ratio of the calorimeter, ultimately providing a fundamental guarantee for improving the accuracy of the overall performance test of the compressor.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for simulating and testing the condensation heat transfer law of refrigerant in a calorimeter, characterized by the following steps:

[0006] S1. Conduct a test to calibrate the heat loss of the calorimeter simulation device:

[0007] The calorimeter simulation device has a built-in cold coil, and the outlet of the cold coil is connected to the first inlet of the water tank. The second outlet of the water tank is connected to the inlet of the cold coil via a water pump and a flow meter. It also includes an air-cooled chiller unit, whose inlet and outlet sides are respectively connected to the second inlet and the second outlet of the water tank.

[0008] First, turn on the electric heater of the calorimeter simulation device and adjust the heating power of the electric heater. Then, adjust and stabilize the electric heating power to make the internal pressure P1 of the calorimeter simulation device reach a stable state. Record the power Q1 of the electric heater, the second refrigerant saturation temperature Ts, and the ambient temperature T of the calorimeter simulation device under this stable state.

[0009] The calibrated heat loss Q and heat loss coefficient F of the calorimeter simulation device are calculated using the following formula:

[0010]

[0011] F = Q / (Ts-T);

[0012] S2. Conduct heat leakage and heat transfer tests on the calorimeter simulation device under set operating conditions:

[0013] S21. Turn on the water pump and set the inlet flow rate q using the flow meter;

[0014] S22. Adjust the inlet water temperature T1 of the cold coil in the calorimeter simulation device, turn on the air-cooled chiller unit to provide the water tank with cold water that is lower than the inlet water temperature T1 of the cold coil, and turn on the electric heater of the water tank to make the inlet water temperature T1 of the cold coil reach the set inlet water temperature.

[0015] S23. Adjust the heating power of the electric heater of the calorimeter simulation device so that the outlet water temperature T2 of the cold coil reaches the set outlet water temperature;

[0016] S24. Once the inlet water flow rate q, the inlet water temperature T1 of the cold coil, and the outlet water temperature T2 of the cold coil are all stable, record the power Q1, internal pressure P1, internal temperature T4, wall temperature T3, ambient temperature T, as well as the inlet water flow rate q, inlet water temperature T1, and outlet water temperature T2 of the cold coil in the calorimeter simulation device.

[0017] The actual heat loss Qs and actual heat loss coefficient Fs of the calorimeter simulation device are calculated using the following formula:

[0018] Qs=qCρ(T2-T1)-Q1

[0019] Fs = Qs / (T4-T)

[0020] Where C is the specific heat capacity of water, and ρ is the density of water;

[0021] S3. The heat leakage ratio ξ is calculated using the following formula:

[0022] ξ = 100% * |(Q-Qs) / Q|.

[0023] Preferably, an observation hole is provided on the outer wall of the calorimeter simulation device; during the operation of step S2, a high-speed photography device is arranged at the observation hole to observe the condensation process of the second refrigerant vapor on the wall of the cold coil.

[0024] Preferably, it also includes a refrigerant recovery device for changing the type of refrigerant within the calorimeter simulation device.

[0025] Preferably, the cooling coil is a copper tube or a condenser tube with a pore-refined surface treatment.

[0026] Preferably, in step S1, the stable state further includes: the second refrigerant saturation temperature Ts is 15°C higher than the ambient temperature T, and the ambient temperature T < 43°C, with temperature fluctuation ≤ ±1°C.

[0027] The beneficial effects of this invention are as follows:

[0028] 1) Through the above scheme, this invention can achieve the maximum simulation of the internal working conditions of a specified calorimeter. By simultaneously controlling the inflow rate and temperature of the water entering the cold coil inside the calorimeter simulation device, and in conjunction with the electric heater inside the calorimeter simulation device, precise control of the pressure and temperature distribution within the calorimeter simulation device can be achieved, thereby maximizing the elimination of the influence of unstable factors such as measurement methods, instruments, environmental fluctuations and deviations, and interference factors. Furthermore, the operation steps of this invention are extremely simple and effective, and easy to use, ensuring the feasibility of testing the internal condensation heat transfer law of a specified calorimeter. The stability of the test system operation can also be effectively guaranteed, achieving the goal of accurate measurement of various key parameter values, ultimately providing a fundamental guarantee for improving the accuracy of compressor overall performance testing.

[0029] 2) This invention can be used with observation holes and high-speed photography equipment to observe, photograph and record the condensation mechanism of the cold coil wall in the calorimeter simulation device; this is not only beneficial for later review, but also can be used to reveal the condensation mechanism of the second refrigerant currently used by comparing with the current phenomenon, providing a theoretical basis for the accurate selection of the second refrigerant in the future. Attached Figure Description

[0030] Figure 1 This is a pipeline layout diagram of the present invention.

[0031] The actual correspondence between the reference numerals and component names in this invention is as follows:

[0032] 10-Calligrapher simulation device; 11-Cold coil; 12-Observation port;

[0033] 20 - Water tank; 30 - Water pump; 40 - Air-cooled chiller unit. Detailed Implementation

[0034] For ease of understanding, this section combines... Figure 1The specific structure and operation of the present invention are further described below:

[0035] The testing work of this invention is based on, as follows Figure 1 The test was conducted based on the system shown. This system includes a calorimeter simulation device 10 with a built-in cold coil 11. The outlet of the cold coil 11 is connected to the first inlet of the water tank 20, and the second outlet of the water tank 20 is connected to the inlet of the cold coil 11 via a water pump 30 and a flow meter. The system also includes an air-cooled chiller unit 40, whose inlet and outlet are connected to the second inlet and second outlet of the water tank 20, respectively. Several thermometers are arranged in the system to facilitate temperature measurements at designated points; similarly, pressure gauges are used.

[0036] Furthermore, in designing the test system: the air-cooled chiller unit 40 is used to provide low-temperature chilled water, and the water tank 20 is used to store the chilled water. Two electric heaters are used to facilitate online temperature control of the water tank 20 and the cooling coil 11 inside the calorimeter simulation device 10, respectively. A flow meter is used to collect the inlet water flow rate into the calorimeter simulation device 10, and a water pump 30 is used to regulate the inlet water flow rate into the calorimeter simulation device 10. A standard platinum resistance thermometer can be used to record the temperature at each measuring point. Thermocouples can also be arranged to record the temperature distribution on the outer wall of the calorimeter simulation device 10, and a pressure sensor can be used to record the internal pressure of the calorimeter simulation device 10.

[0037] Thus, the testing system can now perform heat loss testing on a specified calorimeter and mass transfer testing on the internal second refrigerant.

[0038] Therefore, the following operational process of the present invention can be carried out:

[0039] S1. Conduct a test on the calibrated heat leakage of the calorimeter simulation device 10:

[0040] First, turn on the electric heater of the calorimeter simulation device 10, adjust the heating power of the electric heater, and then adjust and stabilize the electric heating power so that the internal pressure of the calorimeter simulation device 10 is P1 = 161 kPa, thereby reaching a stable state; record the power of the electric heater in the calorimeter simulation device 10 under this stable state as Q1 = 104 W, the second refrigerant saturation temperature as Ts = 41.26℃, and the ambient temperature as T = 24.30℃.

[0041] The calibrated heat loss Q and heat loss coefficient F of the calorimeter simulation device 10 are calculated using the following formula:

[0042] Q = Q1 = 104W

[0043] F=Q / (Ts-T)=104 / (41.26-24.30)=6.13W / ℃;

[0044] S2. Conduct heat leakage and heat transfer tests on the calorimeter simulation device 10 under set operating conditions:

[0045] S21. Turn on water pump 30 and set the inlet flow rate q = 1.51 m³ / h using the flow meter. 3 / h;

[0046] S22. Adjust the inlet water temperature T1 of the cold coil 11 in the calorimeter simulation device 10 to 4.02℃, turn on the air-cooled chiller unit 40 to provide cold water to the water tank 20 at a temperature lower than the inlet water temperature T1 of the cold coil 11, and turn on the electric heater of the water tank 20 so that the inlet water temperature T1 of the cold coil 11 reaches the set inlet water temperature.

[0047] S23. Adjust the heating power of the electric heater of the calorimeter simulation device 10 so that the outlet water temperature T2 of the cold coil 11 reaches the set outlet water temperature of 6.08℃;

[0048] S24. Once the inlet water flow rate q, the inlet water temperature T1 of the cold coil 11, and the outlet water temperature T2 of the cold coil 11 are all stable, record the following values ​​within the calorimeter simulation device 10: power Q1 = 3.651 kW, internal pressure P1 = 105.36 kPa, internal temperature T4 = 27.47℃, wall temperature T3 = 26.98℃, ambient temperature T = 25.12℃, and inlet water flow rate q of the cold coil 11 = 1.51 m³ / s. 3 / h, the inlet water temperature of cold coil 11 is T1 = 4.02℃ and the outlet water temperature of cold coil 11 is T2 = 6.08℃;

[0049] The actual heat loss Qs and actual heat loss coefficient Fs of the calorimeter simulation device 10 are calculated using the following formula:

[0050] Qs=qCρ(T2-T1)-Q1=1000*4.205*1.51*(6.08-4.02)-3.708=-0.018kWFs=Qs / (T4-T)=18 / (27.47-25.12)=7.66W / ℃

[0051] Where C is the specific heat capacity of water, which is 4.205 kJ / (kg*K); ρ is the density of water, which is 1000 kg / m³. 3 ;

[0052] S3. The heat leakage ratio ξ is calculated using the following formula:

[0053] ξ=100%*|(Q-Qs) / Q|=100%*|1-Qs / (F*(T4-T))|

[0054] =100% * |1-18 / (6.13*2.35)| = 24.95%.

[0055] From the beginning of step S2 until the parameters stabilize, that is, in steps S21 to S24, a high-speed photography device is used to photograph and record the condensation process of the second refrigerant vapor on the wall of the cold coil 11 inside the calorimeter simulation device 10 through the observation hole 12, so as to reveal the condensation mechanism of the second refrigerant.

[0056] Furthermore, before each test, the type of the second refrigerant in the calorimeter simulation device 10 can be changed using a refrigerant recovery device; the cold coil 11 in the calorimeter simulation device 10 can be replaced, or copper tubes or condenser tubes with a ferrochemically treated surface can be used. These methods effectively increase the testing capability range of the system, facilitating a more in-depth study of the condensation heat transfer characteristics within the calorimeter simulation device 10 under different types of second refrigerants and coil surface parameters.

[0057] Of course, those skilled in the art will recognize that the present invention is not limited to the details of the exemplary embodiments described above, but also includes the same or similar structures that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0059] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

Claims

1. A method for simulating a test based on the condensation heat transfer law of a refrigerant in a calorimeter, characterized by Includes the following steps: S1. Conduct a test to calibrate the heat loss of the calorimeter simulation device (10): The calorimeter simulation device (10) has a built-in cold coil (11), and the outlet of the cold coil (11) is connected to the first inlet of the water tank (20). The second outlet of the water tank (20) is connected to the inlet of the cold coil (11) via a water pump (30) and a flow meter. It also includes an air-cooled chiller unit (40), and the inlet and outlet of the air-cooled chiller unit (40) are connected to the second inlet and the second outlet of the water tank (20) respectively. First, turn on the electric heater of the calorimeter simulation device (10), adjust the heating power of the electric heater, and then adjust and stabilize the electric heating power to make the internal pressure P1 of the calorimeter simulation device (10) reach a stable state; record the power Q1 of the electric heater in the calorimeter simulation device (10), the second refrigerant saturation temperature Ts and the ambient temperature T in this stable state. The calibrated heat loss Q and heat loss coefficient F of the calorimeter simulation device (10) are calculated using the following formula: Q = Q1 F = Q / (Ts-T); S2. Conduct heat leakage and heat transfer tests on the calorimeter simulation device (10) under set operating conditions: S21. Turn on the water pump (30) and set the inlet flow rate q using the flow meter; S22. Adjust the inlet water temperature T1 of the cold coil (11) in the calorimeter simulation device (10), turn on the air-cooled chiller unit (40) to provide the water tank (20) with cold water at a temperature lower than the inlet water temperature T1 of the cold coil (11), turn on the electric heater of the water tank (20) to make the inlet water temperature T1 of the cold coil (11) reach the set inlet water temperature; S23. Adjust the heating power of the electric heater of the calorimeter simulation device (10) so that the outlet water temperature T2 of the cold coil (11) reaches the set outlet water temperature; S24. When the inlet water flow rate q, the inlet water temperature T1 of the cold coil (11) and the outlet water temperature T2 of the cold coil (11) are all stable, record the power Q1, internal pressure P1, internal temperature T4, wall temperature T3, ambient temperature T, inlet water flow rate q, inlet water temperature T1 and outlet water temperature T2 of the cold coil (11) in the calorimeter simulation device (10) at this time. The actual heat loss Qs and actual heat loss coefficient Fs of the calorimeter simulation device (10) are calculated using the following formula: Qs=qCρ(T2-T1)-Q1 Fs = Qs / (T4-T) Where C is the specific heat capacity of water, and ρ is the density of water; S3. The heat leakage ratio ξ is calculated using the following formula: ξ = 100% * |(Q-Qs) / Q|.

2. The method according to claim 1, wherein the method is characterized in that: An observation hole (12) is provided on the outer wall of the calorimeter simulation device (10); during the operation of step S2, a high-speed photography device is arranged at the observation hole (12) to observe the condensation process of the second refrigerant vapor on the wall of the cold coil (11).

3. The method according to claim 1 or 2, wherein the method is characterized in that: It also includes a refrigerant recovery device for changing the type of refrigerant in the calorimeter simulation device (10).

4. A method for simulating and testing the condensation heat transfer law of refrigerant in a calorimeter according to claim 1 or 2, characterized in that: The cold coil (11) is a copper tube or a condenser tube with a pore-refined surface treatment.

5. A method for simulating and testing the condensation heat transfer law of refrigerant in a calorimeter according to claim 1 or 2, characterized in that: In step S1, the stable state further includes: the second refrigerant saturation temperature Ts is 15°C higher than the ambient temperature T, and the ambient temperature T < 43°C, with temperature fluctuation ≤ ±1°C.

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