基于槽式聚光集热的腔体吸收器热损失特性研究

HEAT LOSS PROPERTIES OF CAVITY ABSORBER IN SOLAR COLLECTING SYSTEM WITH PARABOLIC TROUGH CONCENTRATOR

针对太阳能槽式聚光集热系统设计一种三角形腔体吸收器,对其热损失特性建立基于能量衡算和热网络方法的理论分析模型,并进行实验验证。考察腔体吸收器光口倾角、环境风速、保温层厚度、工质流速、工质与环境温差等对各分项热损失和总热损失的影响规律,通过敏感性分析近似拟合出4个二元影响因素对总热损的影响关联式。总热损随工质与环境温差、环境风速呈幂函数正增加趋势,影响较大;与保温层厚度呈对数反增加趋势;与过渡流范围的工质流速呈多项式变化,影响较小;随光口倾角的变化也不大。理论计算值与实测值吻合度高,理论分析模型较准确。结果表明腔体吸收器在无风环境下热损失大小与真空管集热器相当。

A triangle cavity absorber was designed for the solar parabolic trough concentrator system; the theoretical analysis model for heat losses and thermal performance was set up based on energy balance and thermal network method, and then was validated by experimental study. The influences of the inclination angle of absorber cavity, ambient wind speed, thickness of insulation layer, flow rate of working fluid, working fluid and ambient temperature on the heat loss of each item and total heat loss were investigated. The influence of four binary factors on total heat loss was fitted by sensitivity analysis. The total heat loss rose in power function following the increase of temperature difference between the working fluid and the environment, also and the ambient wind speed; being logarithmic inverse increase trend for the thickness of the thermal insulation layer; exhibiting the polynomial change for the flow speed of the working fluid in the transitional flow range with smaller influence; being relatively small for influence of opening tilt angle. The theoretical calculation value agreed well with the measured value, and the theoretical analysis model was more accurate. The results show that the heat loss of cavity absorber is close to that of the vacuum tube collector when there is nearly no wind.