槽式集热器反射镜抛物变形对允许跟踪误差的影响

Influence of reflector deformation on allowed tracking error of parabolic trough collector

为了更好地指导太阳能槽式集热系统的设计和高效运维,本文研究了反射镜抛物变形对集热器允许跟踪误差的影响。首先定义了宽焦比、焦偏比、焦点偏离率3个无量纲参数,理论分析了理想状态不同尺寸下槽式集热器允许跟踪误差,进而给出反射镜剖面抛物变形后的允许跟踪误差的变化;同时计算宽焦比、焦偏比、聚光比对允许跟踪误差的影响并作图,给出基于不同几何参数的槽式集热器在不同变形量下的允许跟踪误差变化及其最大变形量尺寸。结果表明:宽焦比为4时槽式聚光集热器理论允许跟踪误差最大;3个无量纲数耦合影响决定允许跟踪误差的大小,且"膨胀"变形更加不利于集热器聚光。基于本文给出的图表,可预测集热器聚光损失并设计适宜跟踪系统,助力槽式太阳能热利用系统的推广。

To better guide the design and efficient operation and maintennce of solar trough collector system, the influence of the reflector’s parabolic deformation on the allowed tracking error of the collector is investigated. Three dimensionless parameters, such as width focus ratio, focus deviation ratio and focus position deviation rate, are defined. The ideal allowed tracking error of the parabolic trough collector in different sizes is calculated, and the allowed tracking error variation with parabolic deformation of the reflector are given. Moreover, the effect of wide focus ratio, focal deviation ratio and concentration ratio on the allowed tracking error is calculated, and the result is drawn, then the variation of the allowed tracking error and the maximum deformation size are given based on different geometric sizes. The calculation results show that, the theoretical allowed tracking error reaches the maximum when the width focus ratio is 4, the coupling effects of the above three dimensionless parameters determine the value of the allowed tracking error, and the"expansion"deformation is unfavorable for the collector optical concentration. On the basis of the chart given in this paper, the concentrating loss of the collector can be predicted and the suitable tracking system can be designed to promote the application of the parabolic trough solar thermal utilization system.