开缝翅片流动和传热性能的实验研究及数值模拟

对2排X型双向开缝翅片管换热器空气侧的传热及阻力性能进行了实验研究, 在实验的 Re范围内得出了传热和阻力的性能关联式及特性曲线.比较得出,开缝翅片的传热性能远高于平直翅片,与单向开缝翅片相比,X型双向开缝翅片的性能更好.通过数值模拟得出了 X型双向开缝翅片的效率计算曲线.应用场协同原理,对数值模拟得到的气流在2片翅片之间的温度场、速度场、对流换热系数及压降在流动方向上的沿程变化进行了分析.结果表明,开缝翅片有效强化传热的根本原因是翅片开缝后改善了速度和温度梯度的协同性.

Experimental and Numerical Study on Heat Transfer and Fluid Flow Characteristics of Slotted Fin-and-Tube Heat Transfer Surfaces

Air side heat transfer and fluid flow characteristics of two-row slotted fin-and-tube heat transfer surface with X-type strip arrangement were studied experimentally and numerically. The heat transfer and friction factor correlations were obtained in a wide range of Reynolds number. It is found that the slotted fin-and-tube heat transfer surfaces have excellent performance compared with the plain plate fin heat transfer surfaces and the performance of X-type two-side strip fin surfaces is better than that of one-side strip fin surfaces. By numerical method, the fin efficiency curves for X-type two-side strip fin surfaces were achieved. From the viewpoint of field synergy, the air velocity and temperature fields between the two neighboring fin surfaces and the distribution of local heat transfer coefficient and pressure drop in flow direction were analyzed. The results show that the heat transfer enhancement of slotted fins is caused by the improvement of the synergy between the velocity field and the temperature gradient.