不同冷却方式下换热系数的测量与计算

The Measurement and Calculation of Heat Transfer Coefficient under Different Cooling Conditions

为了研究不同冷却方式下的换热系数,设计了一套可以测量空冷、水淬以及不同压力下喷气淬火下冷却曲线的试验装置,试验中测量的探头采用120mm×120mm×20mm奥氏体不锈钢方板。该探头经有限元(FEM)计算验证了其一维传热特性后,用来测量上述几种冷却方式下的冷却曲线,并用反传热法(IHCM)和集中热容法(LHCM)进行换热系数的计算与分析,比较了不同压力下喷气淬火的换热系数。实验结果表明,当毕欧数Bi<0.1时集中热容法是适用的,反之则不适用;在喷气淬火时,压力越大,表面换热系数也越大。

In order to determine the heat transfer coefficient under different cooling conditions, an experiment apparatus is designed to measure the cooling curves of air, water and different-pressure air spray cooling. A 120mm×120mm×20mm flat sample, proved to be one-dimension heat conduction by finite element method(FEM), is adopted for the measurement in this experiment. Both the Inverse Heat Conduction Method (IHCM) and Lumped Heat Capacity Method (LHCM) are used in the calculation of heat transfer coefficient. The results of air spray cooling are also discussed based on different pressures. The experiment results indicate that LHCM is applicable only when Bi<0.1 and also indicate that during air spray cooling, the higher the pressure is, the greater the heat transfer coefficient is.