板翅式换热器平直翅片表面流动及传热特性

为了提高板翅式换热器的换热性能,采用CFD数值模拟方法,研究了翅片结构参数和入口Re数对板翅式换热器平直翅片的表面传热与流动阻力特性的影响。研究结果表明:当流体被加热时,翅片通道内部靠近固体壁面的流体温度较高,通道中心主流体区温度较低。流体在翅片通道内的温度分布呈一定梯度,靠近一次表面的流体温度梯度较大,而靠近二次表面的流体温度梯度较小。随着翅片高度和翅片间距的增加,平直翅片的表面传热因子和摩擦因子增大。而且,增加翅片的厚度,可在一定程度提高其换热性能,但翅片厚度存在一个最优值。研究结果可为板翅式换热器的优化设计提供理论指导。

Fluid flow and heat transfer characteristics in plain fins of plate-fin heat exchanger

In order to improve the performance of plate-fin heat exchanger,a three-dimensional numerical investigation of fluid flow and heat transfer characteristics in plain fins of plate-fin heat exchanger was performed using CFD software.The effect of configuration and average inlet Re number on the characteristics in plain fins was studied.The results show that the temperature of fluid adjacent to the wall is higher while that of central fluid is lower when fluid is heated.There is obvious temperature gradient in the fluid.It is higher near the wall while lower in the central fluid.The values of j-factor and f-factor all increase with the height and spacing of plain fins.With the increase in fin thickness,the heat transfer performance of plain fins is intensified to some extent while there is an optimum value.The numerical results are in good accordance with the reported experimental values.The results provide the theoretical basis for the optimum design of plate-fin heat exchangers.