V形肋片型太阳能空气集热器换热特性的研究

本文运用数值模拟的方法,对带有多重V形肋片的平板型太阳能空气集热器的换热与流动特性进行了研究。在雷诺数5 000~20 000范围内,采用RNG k-ε湍流模型,研究了相对肋宽比(W/w)对集热器换热特性的影响规律,并对集热器内部流场进行了分析。研究结果表明,V形肋片增强了空气的对流换热。这是由于流体掠过肋片后,产生旋涡和回流,加强了流体扰动,从而使换热增强。相对其它肋宽比而言,W/w=6时,集热器具有较好的换热效果,努塞尔数为光滑壁面的2.54倍,但肋片的存在导致摩擦损失增加,换热性能因数最大为1.55。

Study on Heat Transfer Characteristics of Solar Air Collector with V-shaped Ribs

A numerical simulation is conducted for the flow and heat transfer characteristics in solar air collector with multi v-shaped fins.Effects of the relative roughness width ratio （W/w） on the heater transfer performance and flow field were investigated adopting the RNG k-ε turbulence model for the Reynolds number range from 5 000 to 20 000.The results show that usage of the v-shaped fins can enhance the convective heat transfer as a result of the disturbance of the vortex and the backflow that form during the air flow pasts the v-shaped fins.Compared with other values of W/w,air collector has better heat transfer enhancement at W/w =6 and the Nusselt number is 2.54 times of that without fins.However,using the fins leads to the increase of the friction loss.The maximum thermal enhancement factor is 1.55.