开孔折流板型太阳能空气集热器流动传热特性研究

Study of the Flow and Heat Transfer Characteristics of a Hole-opened Type Deflection Plate Solar Power Air Heat Collector

对开孔型折流板太阳能空气集热器内部流动和传热特性进行了数值模拟研究。结果表明:开孔射流与主流的相互作用使折流板背侧分离涡范围变小,同时产生更多小范围涡旋,使得流体掺混更加充分,腔内气流温度分布更为均匀,集热板和玻璃盖板的温度有不同程度降低。对一个含4块折流板,每块折流板开3个孔的集热器,在入口流量为0.013kg/(s·m^2)的条件下,与原型集热器相比,开孔型集热器进出口总压损失下降8.8%,集热板平均辐射散热损失下降12.29%,玻璃盖板总热损失下降9.1%,折算成集热效率提高3.6%。同时,发现折流板开孔对集热器第一腔的流动和换热特性没有显著影响,如要提高进一步集热效率,还应设法改善第一腔室的气流组织。

A numerical and simulation study was performed of the internal flow and heat transfer characteristics of a holeopened type deflection plate solar power air heat collector. It has been found that the interactions between the jet going out from the holes and the main stream will force the range of the vortex separated from the back of the deflection plate to become small and at the meantime,produce more vortexes in small ranges,therefore,making the jet and the main stream fulfill a sufficient dilution and mixing,the air temperature distribution in the cavity more uniform and the temperatures of the heat collection plate and glass cover drop to different extents. For a heat collector with four deflection plates,each of which has three holes,under the condition of the flow rate at the inlet equaling to 0. 013 kg/( s·m^2),compared with the prototype heat collector,the total pressure loss between the inlet and outlet of the hole-opened type heat collector will decrease by 8. 8%,the average radiation-caused heat dissipation loss of the heat collecting plates will go down by 12. 29%,the total heat loss of the glass cover will be down by9. 1% and the heat collection efficiency will increase by 3. 6% after a conversion has been made. Simultaneously,it has been found that the holes opened on the deflection plates have no obvious influence on the flow and heat exchange characteristics of the first cavity in the heat collector. To further enhance the heat collection efficiency,efforts shall be made to improve the air distribution inside the first cavity.