管翅换热器换热与流动的三维定常特性分析

为了深入了解单排管翅式换热器换热和流动特性,在雷诺数为100~600之间,翅片间空气为定常层流条件下,利用复合坐标网格系统及对流、导热相结合的数值分析方法,对5种不同几何参数平板翅紧凑管翅式换热器的流场、温度场、换热系数、传热量、压降、翅片效率进行了模拟计算和分析。结果表明:翅片越薄,单位体积、单位质量的传热量越大;在一定雷诺数条件下,存在一个最佳的翅片间距,并使得换热量最大;对所讨论的5种情况来说,当雷诺数为400时,翅片宽度较小的?热器的总传热量比其他4类高10%左右,但压力损失的降低变化不大。无论在哪种条件下,翅片后半部的传热量占全部传热量的25%以下,并且当雷诺数较低时,该比例会更低。

Flowing and heat transfer characteristics for three-dimensional steady flows of plate-fin tube heat exchangers with one row tube

For understanding of flowing and heat transfer characteristics of plate-fin tube heat exchangers with one row tube,this paper adopted the block-structured grid system and numerical calculation method of heat conduction and heat convection combine together,carried out the numerical computations of velocity field,temperature field,fin efficiency and pressure loss for three-dimensional steady flows of five different types plate-fin tube heat exchanger with one row tube in Reynolds number between 100-600.The effects of different geometric parameters on flow and heat transfer performance have been investigated.The results show that: the thinner the fin thickness,the more the heat transfer capacity of per unit volume and per unit mass.There is an optimum fin pitch in a given Reynolds number.When Reynolds number is 400,the heat exchanger with the lowest fin width has a 10% increase in the heat transfer capacity than other above-mentioned 5 types,and the change of the pressure loss is smaller.Heat transfer capacity of second half of the fin is 25% of total heat transfer capacity,and also this proportion becomes smaller in low Reynolds number.