A quick calculation method for determining air volume configuration of oil-immersed transformer cooling system

Abstract

The application discloses a kind of quick calculation method for determining the air volume configuration of oil-immersed transformer cooling system, the method considers that transformer develops to "lightweight, miniaturization" direction, cooling system intensification is a kind of inevitable trend, accurately configure cooling fan diameter can both ensure efficient heat dissipation, and can avoid problems such as high cost, heavy quality and large wind loss, and is in harmony with the concept of "light" and "small". The method comprises establishing a thermal hydraulic model considering the correlation of air volume change, introducing air leakage parameters and performing conjugate heat transfer calculation between the oil domain and the air domain, obtaining characteristic parameters reflecting the dynamic behavior of the heat exchanger coupled fluid. This method is to quickly obtain the thermal characteristic factors and wind loss of the heat exchanger under oil-immersed air cooling mode during the design and development stage to ensure reasonable and efficient heat dissipation of the transformer cooling system.

Description

Technical Field

[0001] This invention relates to a rapid calculation method for determining the airflow configuration of an oil-immersed transformer cooling system. It is used to quickly and accurately obtain important heat flow characteristic parameters within the transformer radiator, providing key information on the global design parameters of the transformer radiator at a relatively low cost. It belongs to the field of high-efficiency cooling optimization design for power transformers. Background Technology

[0002] As a core supporting device in the power system, transformers play a vital role in voltage transformation and power transmission. In recent years, transformers have rapidly developed towards miniaturization, lightweighting, and intensification. Efficient and rationally optimized cooling configurations can prevent transformer temperatures from exceeding limits and causing insulation breakdown. Therefore, the importance of researching external cooling systems to effectively extend insulation life and ensure long-term reliable operation is self-evident.

[0003] Current research on cooling systems for oil-immersed transformers mainly focuses on internal control and external structural optimization. Internal control often employs finite element numerical simulation calculations, which locally affect the overall oil temperature by altering the structure of any segment of the oil circuit, thus improving the transformer's heat dissipation performance. External optimization involves modifying the radiator structure or fan arrangement to maximize heat dissipation. However, there is a lack of literature on the efficient and rational utilization of external cooling air in transformers. Considering the confined internal structure of high-speed trains, a single fan with an excessively small diameter will only effectively dissipate heat from a small portion of the thin fins, leaving the overall oil temperature still too high. Conversely, if the fan diameter is too large, while the internal oil temperature may be cooled to a limited value, the fan will face issues such as high cost, heavy weight, and excessive wasted airflow, contradicting the "lightweight" concept. Therefore, including airflow loss as an evaluation factor is a crucial aspect of ensuring the efficient operation of the cooling system.

[0004] This invention comprehensively considers the balance between wind loss and the temperature difference between the top and bottom layers of oil, and proposes a quick calculation method for determining the airflow configuration of the cooling system of an oil-immersed transformer. Its purpose is to efficiently obtain key parameters of the coupled thermal fluid dynamic behavior of the radiator in the oil-immersed air-forced (ONAF) mode during the design and development stages. Summary of the Invention

[0005] The purpose of this invention is to provide a quick calculation method for determining the airflow configuration of an oil-immersed transformer cooling system. By establishing a thermal-hydraulic calculation model that takes into account airflow loss, the internal heat flow characteristic parameters of the radiator can be quickly obtained, avoiding the need to spend a lot of time and money on experiments and simulations during the design and development stages. This provides a new idea and method for cooling optimization design.

[0006] This invention is achieved through the following technical approach:

[0007] A rapid calculation method for determining the airflow configuration of an oil-immersed transformer cooling system, characterized by comprising the following steps:

[0008] Step 1: Record the nameplate information of a specific oil-immersed transformer, the structural characteristic parameters of the radiator, the oil passage and air passage parameters of the heat sink, the initial wind speed and air volume of the cooling fan, the ambient temperature, the inlet oil temperature and oil flow rate of the top layer of the radiator, and establish a thermal-hydraulic model of the transformer radiator that takes into account the dynamic loss correlation of air volume.

[0009] Step 2: Based on the aforementioned transformer radiator thermal-hydraulic model that takes into account the dynamic loss correlation of air volume, input the basic structural parameters of the transformer radiator and the diameter, initial wind speed and air volume of the cooling fan;

[0010] Step 3: Calculate the thermal characteristic parameters of the oil flow side and the air side based on the aforementioned thermal-hydraulic model;

[0011] Step 4: Based on the obtained transformer oil flow thermal characteristic parameters, use them as the basis for judging the efficient cooling of the radiator and determine that the temperature difference between the top and bottom layers of the radiator oil is greater than the expected value; if not, adjust the diameter of a single fan and return to step 3.

[0012] Furthermore, under the excitation of a single fan, the Y1 portion of the heatsink undergoes natural convection (N), at which point the heat dissipation power is ∑P. Nx (x=1,2…Y1), where Y2 is forced convection (F), and the heat dissipation power is ∑P Fy (y=1,2…Y2), the total heat dissipation power is P, and the thermo-hydraulic model of the transformer radiator is based on the energy conservation equation:

[0013]

[0014]

[0015]

[0016]

[0017] In the formula, ρ air Cp air Q air For the specific heat capacity, density, and mass flow rate of air, ρ oil Cp oil Q oil For the specific heat capacity, density, and mass flow rate of the oil, α coef The overall heat transfer coefficient is given by r, which is the coordinate height perpendicular to the heat sink, and θ is a calculated quantity determined by parameters such as fluid properties and heat transfer coefficient. T oil_in With T oil_out These are the top-level inlet oil temperature and the bottom-level outlet oil temperature, T air1It is the inlet air temperature, T air2 It is the outlet air temperature, ΔT oil-air It is the temperature difference between the cooling oil and the air, r ra It refers to the height of the radiator;

[0018] Furthermore, the heat transfer coefficient in the thermal-hydraulic model is calculated as follows:

[0019]

[0020] T oil_in =T oil_inF =T oil_inN

[0021]

[0022]

[0023]

[0024] In the formula, α oil Oil zone heat transfer coefficient, α air It is the air domain heat transfer coefficient, α Al It is the heat transfer coefficient of the aluminum heat sink, T oil_inN and T oil_inF These are the top inlet oil temperatures under natural convection and forced convection, respectively, ∑Q oilNx (x=1,2…Y1), ∑Q oilFy (y=1,2…Y2), ∑Q airNx (x=1,2…Y1), ∑Q airFy (y = 1, 2, ..., Y2+1) represent the mass flow rates of cooling oil and cooling air, respectively, under natural convection and forced convection.

[0025] The thermal characteristic parameters of the cooling oil are solved using the laws of conservation of mass, momentum, and energy on the oil flow side. The calculation formula is as follows:

[0026]

[0027]

[0028] In the formula, ΔN oil For the thermal buoyancy force of oil flow circulation, β oil Let g be the coefficient of thermal expansion of the oil, g be the acceleration due to gravity, and r be the acceleration due to gravity. w-r T represents the height difference between the winding and the heat sink. env For ambient temperature, ΔT L v is the logarithmic mean temperature difference between the oil and air in the radiator. oil Let be the kinematic viscosity of the oil, s be the area of ​​the oil flow channel, and p be the area of ​​the flow channel. e Let η be the circumference of the oil passage.oil These are empirical constants related to the channel shape;

[0029] The cooling air distribution characteristics between the heat sinks are solved using the laws of conservation of mass and momentum on the air side, and the airflow leakage parameter is introduced. The calculation formula is as follows:

[0030]

[0031]

[0032] In the formula, i is the number of local air ducts of the radiator (i = 1, 2, 3), Δp i W represents the total pressure drop difference in the heatsink airflow channel. path_loss For losses along the path, W partial_loss For local losses, λ is the friction loss coefficient, and l s The length of the initial wind development stage, l e The length of the attenuation wind phase, Let D be the average wind speed of the cooling air in the i-th air duct. i Let Re be the hydraulic diameter of the i-th heat sink air duct. airF The Reynolds number of air;

[0033] The local loss coefficient τ caused by the change in cross-sectional area in the cooling airflow i The calculation formula is as follows:

[0034]

[0035] In the formula, D is the average velocity of the initial cooling airflow. fan d is the fan diameter. fron This is the distance the initial airflow travels into the heatsink's airflow channel;

[0036] The formula for calculating the initial air volume of cooling air is as follows:

[0037]

[0038] In the formula, Q air w represents the total mass flow rate of the initial cooling air. air It is the total height of the air duct, μ air Let s be the kinematic viscosity of air. air d is the area of ​​the air duct, β is the perimeter of the air duct, and β is the circum air These are empirical constants related to the shape of the air passage;

[0039] Input the structural characteristic parameters of the radiator, the oil passage and air passage parameters of the heat sink, the initial wind speed of the cooling fan, the ambient temperature, the oil temperature and oil flow rate at the top inlet of the radiator, adjust the fan diameter, and use the wind loss correlation to obtain the air volume loss and the bottom oil temperature.

[0040] The benefits and results achieved by utilizing the above technical approach are as follows:

[0041] 1. Based on the heat flow characteristics of oil-immersed transformers, this invention proposes a low-cost and high-accuracy analytical equation model. This model solves a set of coupled nonlinear equations for natural and forced convection heat dissipation, introduces simplified equations for the airflow characteristics of fluid mechanics fans, and solves the calculation of various flow and thermal characteristic parameters of the cooling circuit.

[0042] 2. This invention saves on expensive experimental costs and avoids spending a lot of time on mesh simulation, saving computer resources and reproducing important design variable values ​​with high-precision results, which provides new ideas and methods for cooling optimization design. Attached Figure Description

[0043] Figure 1 This is a technical flowchart of an embodiment of the present invention;

[0044] Figure 2 This is a plan view of the coupling of natural convection and forced thermal convection in an oil-immersed transformer according to an embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of the airflow inside the radiator according to an embodiment of the present invention;

[0046] Figure 4 This is a graph showing the ratio of temperature difference to wind loss under different fan diameters in embodiments of the present invention. Detailed Implementation

[0047] The present invention will now be described in conjunction with specific embodiments and the accompanying drawings. It should be emphasized that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the scope of the invention's concept or claims.

[0048] In recent years, transformers have rapidly developed towards miniaturization, lightweighting, and intensification. Efficient and rational cooling optimization can prevent transformer temperatures from exceeding limits and causing insulation breakdown. To effectively extend insulation life and ensure long-term reliable operation, the importance of research on external cooling systems is self-evident. Considering the trend towards "lighter" and "smaller" transformers, a fan with too small a diameter will only provide good heat dissipation for a small portion of the thin fins, leaving the overall oil temperature too high. Conversely, if the fan diameter is too large, while the internal oil temperature may be cooled to the limit, the fan will face problems such as high cost, heavy weight, and excessive airflow waste, contradicting the "lightweight" concept. Therefore, including airflow loss as an evaluation factor is crucial for ensuring efficient operation of the cooling system. This invention comprehensively considers the balance between airflow loss and the temperature difference between the top and bottom layers of oil, proposing a rapid calculation method for determining the airflow configuration of an oil-immersed transformer cooling system. Its purpose is to efficiently obtain key parameters of the coupled thermal fluid dynamic behavior of the radiator in oil-immersed air-forced (ONAF) mode during the design and development stages. The specific technical roadmap is as follows: Figure 1 As shown;

[0049] Specifically, the present invention provides a rapid calculation method for determining the airflow configuration of an oil-immersed transformer cooling system, characterized by comprising the following steps:

[0050] Step 1: Record the nameplate information of a specific oil-immersed transformer, the structural characteristic parameters of the radiator, the oil passage and air passage parameters of the heat sink, the initial wind speed and air volume of the cooling fan, the ambient temperature, the inlet oil temperature and oil flow rate of the top layer of the radiator, and establish a thermal-hydraulic model of the transformer radiator that takes into account the dynamic loss correlation of air volume.

[0051] Step 2: Based on the aforementioned transformer radiator thermal-hydraulic model that takes into account the dynamic loss correlation of air volume, input the basic structural parameters of the transformer radiator and the diameter, initial wind speed and air volume of the cooling fan;

[0052] Step 3: Calculate the thermal characteristic parameters of the oil flow side and the air side based on the aforementioned thermal-hydraulic model;

[0053] Step 4: Based on the obtained transformer oil flow thermal characteristic parameters, use them as the basis for judging the efficient cooling of the radiator and determine that the temperature difference between the top and bottom layers of the radiator oil is greater than the expected value; if not, adjust the diameter of a single fan and return to step 3.

[0054] Furthermore, under the excitation of a single fan, the Y1 portion of the heatsink undergoes natural convection (N), at which point the heat dissipation power is ∑P. Nx (x=1,2…Y1), where Y2 is forced convection (F), and the heat dissipation power is ∑P Fy(y=1,2…Y2), the total heat dissipation power is P, and the thermo-hydraulic model of the transformer radiator is based on the energy conservation equation:

[0055]

[0056]

[0057]

[0058]

[0059] In the formula, ρ air Cp air Q air For the specific heat capacity, density, and mass flow rate of air, ρ oil Cp oil Q oil For the specific heat capacity, density, and mass flow rate of the oil, α coef The overall heat transfer coefficient is given by r, which is the coordinate height perpendicular to the heat sink, and θ is a calculated quantity determined by parameters such as fluid properties and heat transfer coefficient. T oil_in With T oil_out These are the top-level inlet oil temperature and the bottom-level outlet oil temperature, T air1 It is the inlet air temperature, T air2 It is the outlet air temperature, ΔT oil-air It is the temperature difference between the cooling oil and the air, r ra It refers to the height of the radiator;

[0060] Furthermore, a key factor in the thermal-hydraulic model is the calculation of the heat transfer coefficient:

[0061]

[0062] T oil_in =T oil_inF =T oil_inN

[0063]

[0064]

[0065]

[0066] In the formula, α oil Oil zone heat transfer coefficient, α air It is the air domain heat transfer coefficient, α Al It is the heat transfer coefficient of the aluminum heat sink, T oil_inN and T oil_inF These are the top inlet oil temperatures under natural convection and forced convection, respectively, ∑Q oilNx (x=1,2…Y1), ∑QoilFy (y=1,2…Y2), ∑Q airNx (x=1,2…Y1), ∑Q airFy (y = 1, 2, ..., Y2+1) represent the mass flow rates of cooling oil and cooling air, respectively, under natural convection and forced convection.

[0067] The thermal characteristic parameters of the cooling oil are solved using the laws of conservation of mass, momentum, and energy on the oil flow side. The calculation formula is as follows:

[0068]

[0069]

[0070] In the formula, ΔN oil For the thermal buoyancy force of oil flow circulation, β oil Let g be the coefficient of thermal expansion of the oil, g be the acceleration due to gravity, and r be the acceleration due to gravity. w-r T represents the height difference between the winding and the heat sink. env For ambient temperature, ΔT L v is the logarithmic mean temperature difference between the oil and air in the radiator. oil Let be the kinematic viscosity of the oil, s be the area of ​​the oil flow channel, and p be the area of ​​the flow channel. e Let η be the circumference of the oil passage. oil These are empirical constants related to the channel shape;

[0071] Considering the existence of the wind loss factor, when using the law of conservation of mass and momentum on the air side to solve for the cooling air distribution characteristics between the heat sinks, it is also necessary to introduce the airflow leakage parameter. A schematic diagram of the airflow inside the heat sink is shown below. Figure 3 The calculation formula is as follows:

[0072]

[0073]

[0074] In the formula, i is the number of local air ducts of the radiator (i = 1, 2, 3), Δp i W represents the total pressure drop difference in the heatsink airflow channel. path_loss For losses along the path, W partial_loss For local losses, λ is the friction loss coefficient, and l s The length of the initial wind development stage, l e The length of the attenuation wind phase, Let D be the average wind speed of the cooling air in the i-th air duct. i Let Re be the hydraulic diameter of the i-th heat sink air duct. airF The Reynolds number of air;

[0075] The local loss coefficient τ caused by the change in cross-sectional area in the cooling airflow iThe calculation formula is as follows:

[0076]

[0077] In the formula, D is the average velocity of the initial cooling airflow. fan d is the fan diameter. fron This is the distance the initial airflow travels into the heatsink's airflow channel;

[0078] The formula for calculating the initial air volume of cooling air is as follows:

[0079]

[0080] In the formula, Q air w represents the total mass flow rate of the initial cooling air. air It is the total height of the air duct, μ air Let s be the kinematic viscosity of air. air d is the area of ​​the air duct, β is the perimeter of the air duct, and β is the circum air These are empirical constants related to the shape of the air passage;

[0081] Input the structural characteristic parameters of the radiator, the oil passage and air passage parameters of the heat sink, the initial wind speed and air volume of the cooling fan, the ambient temperature, the oil temperature and oil flow rate at the top inlet of the radiator, adjust the fan diameter, obtain the air volume loss value using the wind loss correlation formula, and calculate the bottom oil temperature.

[0082] Example

[0083] Taking an oil-immersed transformer with a rated capacity of 35MVA and a rated voltage of 220kV and its matching PC2600-22 / 520 radiator as an example, its specific parameters are shown in Table 1 below. Tables 2 and 3 are the design parameter values ​​of the oil passage and air passage of the heat sink during the calculation process. Tables 4 and 5 are the fitting functions of the thermal characteristics of the two fluids. Since convection heat dissipation is the main heat dissipation method in ONAF mode, only the heat transfer parameters of the oil domain and the air domain are considered in this embodiment of the invention.

[0084] Table 1 Transformer Parameters

[0085]

[0086] Table 2 Oilway Parameters

[0087]

[0088] Table 3 Duct Parameters

[0089]

[0090] Table 4 Set of Air Thermal Characteristic Parameters

[0091]

[0092]

[0093] Table 5. Set of oil thermal characteristic parameters

[0094]

[0095] In the thermal-hydraulic model of a transformer radiator that takes into account changes in air volume, the calculation formulas for the oil-domain heat transfer parameters are as follows:

[0096] α oil =Nu oil c oil / D oil

[0097] Pr oil =v oil Cp oil / c oil

[0098] Re oil =ρ oil U oil D oil / v oil

[0099]

[0100]

[0101] In the formula: D oil =4s / P e It is the hydraulic diameter of the oil passage, ΔT o-al It is the temperature drop from the oil to the radiator wall, c oil It is the thermal conductivity of oil; Pr oil Gr oil Re oil and Nu oil These are Prandtl number, Grachoff number, Reynolds number, and Nusselt number for pipeline oil flow;

[0102] The formulas for calculating the heat transfer parameters in the air domain are as follows:

[0103] α air =Nu airF c air / D fan

[0104] Pr air =μ air Cp air / c air

[0105]

[0106]

[0107] In the formula: Pr air Re airF and Nu air These are the Prandtl number, Reynolds number, and Nusselt number of air, respectively. oil and T air It refers to the temperature of the oil zone and the air zone, c air It is the thermal conductivity of air, Cp air It is the specific heat capacity of air;

[0108] Based on the above formula, substitute the various physical parameter expressions to calculate the fan diameter D. fan The thermal-hydraulic analytical equations for fan diameters of 155, 255, 355, 455, 555, 655, 755, 855, 955, 1055, 1155, 1255, and 1355 mm were used to calculate wind loss and top-to-bottom oil temperature difference. The data were then visualized, and the ratio of temperature difference to wind loss for different fan diameters is shown in the graph below. Figure 4 ;

[0109] The temperature difference between the top and bottom layers of oil under independent cooling air excitation exhibits a non-linear relationship with the fan diameter. When the fan diameter reaches 655mm, the ratio of temperature difference to air loss (ΔT / ΔQ) tends to level off, and the temperature difference change trend is no longer drastic. However, after 855mm, due to the continuous increase in air loss, the ΔT / ΔQ value continues to decrease. The results show that when the fan diameter is 1.2 to 1.5 times the width of the heat sink, the fan airflow loss is minimized, and the temperature difference between the top and bottom layers of oil is 18K to 20K, achieving the desired cooling effect, and the overall transformer oil temperature is within the specified range.

Claims

1. A rapid calculation method for determining the airflow configuration of an oil-immersed transformer cooling system, characterized in that... It includes the following steps: Step 1: Record the nameplate information of a specific oil-immersed transformer, the structural characteristic parameters of the radiator, the oil passage and air passage parameters of the heat sink, the initial wind speed and air volume of the cooling fan, the ambient temperature, the inlet oil temperature and oil flow rate of the top layer of the radiator, and establish a thermal-hydraulic model of the transformer radiator that takes into account the dynamic loss correlation of air volume. Step 2: Based on the aforementioned transformer radiator thermal-hydraulic model that takes into account the dynamic loss correlation of air volume, input the basic structural parameters of the transformer radiator and the diameter, initial wind speed and air volume of the cooling fan; Step 3: Calculate the thermal characteristic parameters of the oil flow side and the air side based on the aforementioned thermal-hydraulic model; Step 4: Based on the obtained transformer oil flow side thermal characteristic parameters, use them as the basis for judging the efficient cooling of the radiator and determine whether the oil temperature difference between the top and bottom layers of the radiator is greater than the expected value; if not, adjust the diameter of a single fan and return to step 3. In step 1, under the excitation of a single fan, the Y1 portion of the heatsink operates under natural convection, and the heat dissipation power is ∑P. Nx (x=1,2…Y1), where Y2 is forced convection, the heat dissipation power is ∑P Fy (y=1,2…Y2), the total heat dissipation power is P, and the thermo-hydraulic model of the transformer radiator is based on the energy conservation equation: ； ； ； ； In the formula, ρ air C pair Q air For the specific heat capacity, density, and mass flow rate of air, ρ oil C poil Q oil For the specific heat capacity, density, and mass flow rate of the oil, α coef The overall heat transfer coefficient is given by r, which is the coordinate height perpendicular to the heat sink, and θ is a calculated quantity determined by combining fluid properties and heat transfer coefficient. T oil_in With T oil_out These are the top-level inlet oil temperature and the bottom-level outlet oil temperature, T air1 It is the inlet air temperature, T air2 It is the outlet air temperature, ΔT oil-air It is the temperature difference between the cooling oil and the air, r ra It refers to the height of the radiator; Furthermore, the heat transfer coefficient in the thermal-hydraulic model is calculated as follows: ； ； ； ； ； In the formula, α oil Oil heat transfer coefficient, α air It is the air domain heat transfer coefficient, α Al It is the heat transfer coefficient of the aluminum heat sink, T oil_inN and T oil_inF These are the top inlet oil temperatures under natural convection and forced convection, respectively, ∑Q oilNx (x=1,2…Y1), ∑Q oilFy (y=1,2…Y2), ∑Q airNx (x=1,2…Y1), ∑Q airFy (y=1,2…Y2+1) represent the mass flow rates of cooling oil and cooling air, respectively, under natural convection and forced convection.

2. The rapid calculation method for determining the airflow configuration of an oil-immersed transformer cooling system according to claim 1, characterized in that... In step 3, the thermal characteristic parameters of the cooling oil are solved using the laws of conservation of mass, momentum, and energy on the oil flow side. The calculation formula is as follows: ； ； In the formula, ΔN oil For the thermal buoyancy force of oil flow circulation, β oil Let g be the coefficient of thermal expansion of the oil, g be the acceleration due to gravity, and r be the acceleration due to gravity. w-r T represents the height difference between the winding and the heat sink. env For ambient temperature, ΔT L v is the logarithmic mean temperature difference between the oil and air in the radiator. oil Let be the kinematic viscosity of the oil, s be the area of ​​the oil flow channel, and p be the area of ​​the flow channel. e Let η be the circumference of the oil passage. oil These are empirical constants related to the channel shape; The cooling air distribution characteristics between the heat sinks are solved using the laws of conservation of mass and momentum on the air side, and the airflow leakage parameter is introduced. The calculation formula is as follows: ; ； In the formula, i is the number of local air ducts of the radiator (i=1, 2, 3), Δp i W represents the total pressure drop difference in the heatsink airflow channel. path_loss For friction loss, W partial_loss For local losses, λ is the friction loss coefficient, and l s The length of the initial wind development stage, l e v is the length of the attenuation wind phase. i Let D be the average wind speed of the cooling air in the i-th air duct. i Let Re be the hydraulic diameter of the i-th heatsink airflow channel. airF The Reynolds number of air; The local loss coefficient τ caused by the change in cross-sectional area in the cooling airflow i The calculation formula is as follows: ; In the formula, v airF D is the average velocity of the initial cooling airflow. fan d is the fan diameter. fron This is the distance the initial airflow travels into the heatsink's airflow channel; The formula for calculating the initial air volume of cooling air is as follows: ； In the formula, Q air w represents the total mass flow rate of the initial cooling air. air It is the total height of the air duct, μ air Let s be the kinematic viscosity of air. air d is the area of ​​the air duct, β is the perimeter of the air duct, and β is the circumference of the air duct. air These are empirical constants related to the shape of the air passage; Input the structural characteristic parameters of the radiator, the oil passage and air passage parameters of the heat sink, the initial wind speed of the cooling fan, the ambient temperature, the oil temperature and oil flow rate at the top inlet of the radiator, adjust the fan diameter, and use the wind loss correlation to obtain the air volume loss and the bottom oil temperature.

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