双层玻璃盖板平板太阳能集热器数值模拟

Numerical simulation on thermal performance of flat plat solar collector with double glass covers

基于有限容积法建立了双层玻璃盖板平板太阳能集热器的数学模型,对该集热器网格和物理模型进行了有效性验证分析了环境温度、进口水温、太阳辐射强度及下层玻璃盖板位置对集热器热性能的影响,并与单层玻璃盖板平板集热器对比。结果表明:当环境温度低于18℃时,双层玻璃盖板集热器更具优势,当环境温度为-10℃时,双层玻璃盖板集热器瞬时效率比普通平板集热器高0.26;进口水温和太阳辐射强度的提高均可导致集热器内部温度上升,此时双层玻璃盖板的保温效果更加明显,当进口水温为50℃时,双层玻璃盖板集热器比单层玻璃盖板平板集热器的瞬时效率高0.27;当下层玻璃盖板距吸热板上方18mm时,集热器瞬时效率最高可达0.678。本文研究结果有利于对平板式太阳能集热器的工程应用和优化设计。

On the basis of finite volume method, numerical simulation on steady-state thermal performance of flat-plate solar collector with double glass covers were carried out. The physical model of the collector was established and the validation of this model and its grid independence test were both performed. Moreover, through comparison with the conventional plat heat collector, the effects of ambient temperature, inlet water temperature, solar radiate intensity and lower glass cover position on thermal performance of the heat collector were investigated. The results show that,when the ambient temperature is below 18 ℃, the collector with double glass covers shows advantages. When the ambient temperature is - 10 ℃, the instantaneous efficiency of the fiat-plate solar collector with double glass covers is 0.26 higher than that of the conventional plat heat collector. The increase of the inlet water temperature and the solar radiate intensity both result in an increase in the temperature inside the collector, which enhances the insulation effect of the double glass covers. When the inlet water temperature is 50 ℃ ,the instantaneous efficiency difference between the flat-plate solar collector with double glass covers and the conventional one increases to O. 27. When the lower glass cover is located 18 mm over the absorber plate and the solar radiate intensity is 1 000 W/m^2 , the instantaneous efficiency of the flat-plate solar collector with double glass covers can reach up to 0. 678.