不同环境风下改进半球形吸热器换热特性

Heat transfer characteristics of modified hemispherical heat absorber under different ambient winds

为研究改进半球形太阳能腔式吸热器在不同环境风速下的换热性能,建立了吸热器的物理模型,利用TracePro光学模拟软件计算得到吸热管壁的能流分布,折算为体热源加载到吸热管管壁;运用Fluent软件,对倾角在0°—90°的吸热器内导热油与环境的换热特性进行了数值模拟,探究了不同风速和风温下吸热器的各项热损失、导热油出口温度及热效率的变化规律。结果表明:随着环境风速的增加,对流热损失和总热损失呈上升的趋势,出口温度及吸热器热效率呈下降趋势;在低风速下,出口温度及热效率随吸热器倾角的增大而增大,在高风速下,当吸热器倾角在30°时,出口温度和热效率最高;在相同的环境风速下,随着环境温度的升高,吸热器的各项热损失逐渐下降,出口温度呈上升的变化趋势,吸热器的热效率逐渐增大。

In order to study the heat transfer performance of the modified hemispherical solar cavity heat absorber under different ambient wind speeds,the physical model of heat absorber was established.TracePro optical simulation software was used to calculate the heat flux distribution of the heat absorber tube wall which was taken as the thermal boundary condition of the tube wall.The Fluent software was used to simulate the heat transfer between the heat conduction oil and the environment in heat absorber with inclination angles 0°to 90°,and the variation rules of the heat loss,the outlet temperature of the heat conduction oil and the thermal efficiency of the heat absorber under the different wind speeds and temperature were explored.The results show that with the increase of ambient wind speeds,the convective heat loss and total heat loss increase,while the absorber outlet temperature and thermal efficiency gradually decrease.At low wind speeds,the outlet temperature and thermal efficiency increase with the increase of the heat absorber angle.At higher wind speeds,the outlet temperature and thermal efficiency are the highest at 30°.At the same ambient wind speed,with the increase of ambient temperature,the heat loss of the heat absorber gradually decreases while the outlet temperature shows a rising trend,and the heat efficiency of the heat absorber gradually increases.