用于碟式太阳能接收器中高温热管工质的选择

Selection of working fluids for high temperature heat pipes used in dish solar receivers

分析碟式太阳能接收器特点及运行条件,由聚焦后太阳能的特点决定了接收器工作温度范围700-850℃,焦平面处热流密度30-75 W/cm^2。针对接收器目前存在受热面热流量和温度分布不均等问题,将高温热管引入接收器中。高温热管具有极高的传热性能和良好的等温性能,将其用于碟式太阳能接收器中可解决现行接收器受热不均、局部过热等问题。结合碟式太阳能接收器自身特点,从热管内部工质传输系数,工质热物理性能,不同工质高温热管的启动性能以及传热功率等角度分析用于接收器中高温热管常用碱金属工质锂、钠、钾、钠钾合金等。综合考虑以上因素,得出适用于碟式太阳能接收器高温热管工质为钠。

The dish solar receiver＇s working conditions are 700 -850℃ in temperature and 30 -75 W/cm^2 in heat flux, which are determined by the performance of focused solar energy. Since the high temperature heat pipe has the advantages of effective heat transfer performance and ideal isothermal property, it was applied to the receiver to solve the problem of uneven heating and local temperature exceeding. Various working fluids for the high temperature heat pipe, i.e. Li, Na, K, and Na-K, were investigated in the aspects of their transmission coefficient, thermo-physical property, start-up characteristics, and heat transfer performance. The results showed that the suitable working fluid for high temperature heat pipes of dish solar receivers is Na.