Analysis And Optimization Of Heat Dissipation Performance Of Tube-fin Oil Cooler

Oil cooler is an important part to ensure the normal operation of mechanical vehicles.Its heat dissipation capability directly affects the working temperature of the engine,and then affects the dynamic performance and the safe capability of the whole vehicle.With the advantages of simple structure technique and light weight,tube-fin oil cooler has been used by more and more mechanical vehicles.This paper analyzed and studied the heat dissipation capability of the tube-fin oil cooler and optimized the finned structure to improve the heat dissipation performance of the oil cooler.The research contents of this paper are as follows:1.The oil cooler with flat fins was analyzed and studied.The 3D modeling software was used to carry on the overall modeling and the structure was simplified reasonably.The heat dissipated power under different working conditions was obtained by using ANSYS CFX to simulate it globally.The air-cooled oil test was carried out on the flat finned tube-fin oil cooler by the wind tunnel test rig,and the heat capability power under different working conditions was obtained.The test results verified the effectiveness of the simulation model.2.Based on the theory of the heat transfer enhancement,the original flat fin was optimized,and a triangular corrugated fin was proposed on the original structure.Parameterβ as the angle between the peak direction of the triangular corrugation and the direction of the wind speed was introduced,six types of corrugated fins with different β angles was designed,and the established simulation model was used to carry out global simulation on the six types of triangular corrugated fins with different β angles.Under the same working conditions,the heat transfer performance and flow resistance performance of 6 kinds of triangular corrugated fins and straight fins with different β angles were studied.By studying the heat transfer factor j, the friction factor f and the comprehensive coefficient JF,the following conclusions are obtained:when the flow rate at the oil inlet is constant,the heat transfer factor j of six types of triangular corrugated fins and straight fins with different βangles is gradually increased with the increase of the air velocity at the air inlet,the heat transfer factor of the corrugated fin is higher than that of the straight fin,and the friction factor f is also in the same trend.Combined with the comprehensive coefficient JF, the triangle corrugated fin tube fin oil cooler with β=90°has the best comprehensive heat exchange capacity.According to the optimal fin structure,the heat dissipation capability under different fin spacing was studied,and the distribution of the heat dissipation capability under different inlet wind speed was obtained.3.The temperature difference between oil and gas in different air inlet and air inlet was analyzed.The cooling power of the oil cooler under different wind speed and temperature difference between oil and gas was obtained through global simulation and air-cooled oil test,and the correlation between cooling power and wind speed and temperature difference between oil and gas was obtained through using MATLAB for fitting calculation.The correlation formula was verified by using the data under the known working conditions.Most of the error are within 5%,and the maximum error is less than 10%. It is shown that this correlation can be used to calculate the heat dissipation capability of the tube-fin oil cooler under unknown working conditions.4.Based on the MATLAB Graphic User Interface,heat dissipation performance analysis system of the tube-fin oil cooler was designed.The influence of different air inlet wind speed and oil and gas temperature difference on the cooling power of the tube-fin oil cooler can be obtained conveniently and quickly by using this system.The fitting correlation formula was also embedded in the system,which can quickly calculate the heat dissipation capability of the tube-fin oil cooler under unknown working conditions.In order to verify the accuracy of the heat dissipation capability obtained by the correlation formula,the heat dissipation capability of the tube-fin oil cooler under different working conditions can also be accurately calculated by the inlet and outlet temperature differences as well as physical parameters of the oil,a convenient heat dissipation power calculation method is provided for the design of the tube-fin oil cooler in engineering practice.