椭圆管开缝翅片换热表面特性的三维数值分析

研究了平片圆管表面,开缝片圆管和开缝片椭圆管表面的流动和换热特性。翅片表面的缝为辐射布置,下游布置较多的缝。椭圆管的长短轴之比为2.25,与圆管具有相同的周长。研究结果表明,两种开缝片的换热量远大于平片,椭圆管开缝片的压降低于圆管开缝表面。在泵功消耗减少2.5%时,椭圆管开缝的换热量比圆管开缝高7%。椭圆管虽不能改善温度梯度和速度场的协同,然而压降远低于圆管开缝片,使其具有较好的综合特性。

THREE DIMENSIONAL NUMERICAL ANALYSIS FOR SLOTTED FIN-AND-TUBE HEAT TRANSFER SURFACES HAVING OVAL TUBE CONFIGURATION

Fluid flow and heat transfer characteristics of three types of plate fin-and-tube surfaces are numerically investigated, plain plate fin-and-round tube, slotted plate fin-and-round tube, and slotted plate fin-and oval tube. The ratio of the long axis over the short one of the oval tube is 2.25 with the same perimeter length as the round tube. The strips in the slotted fin surfaces are arranged radially, with more strips located in the downstream part of the fin surfaces. It is found that the heat transfer rate of the two slotted fin surfaces is appreciably higher than that of the plain one, and the pressure drop of the oval tube slotted fin surface is much lower than that of the round tube slotted surface. When the pumping power of the oval tube surface is 2.5% lower than that of the round tube surface, the heat transfer rate of the oval slotted fin surface is 7% higher than that of the round tube surface. It is found that the pressure drop of the oval tube is significantly lower than that of slotted round-tube fin surface, leading to its superiority in the thermal-hydraulic performance.