平板型光伏/光热系统高效换热数值模拟研究

NUMERICAL INVESTIGATION ON HIGH-EFFICIENCY HEAT TRANSFER OF PLATE PHOTOVOLTAIC/THERMAL SYSTEMS

针对光伏/光热(PV/T)系统管板换热结构传热性能差、电池层温度分布不均匀的问题,采用管板连接处增加机械加固的形式强化管板导热接触,同时提出蛇形管、单向螺旋型和双向螺旋形3种换热通道分布结构。通过数值模拟方法对比不同结构的系统热性能,随后在流量、辐照度、入口水温等多工况条件下分析换热性能的变化。结果显示:系统在流量90 L/h、辐照度800 W/m~2时呈换热性能最佳状态,热效率能达71.5%;管道具体排布方式对热效率和电池层平均温度的影响不大,而双向螺旋管将冷热管交替布置,较单向螺旋管和蛇形管结构能明显提高电池层温度分布的均匀性,温度分布不均匀度最高可降低37.5%。

The traditional PV/T system has been reported with poor heat transfer performance and non-uniform PV temperature distribution respectively.In this study,the pipe-plate structure in PV/T collector was employed with mechanical reinforcement to reduce the thermal resistance at the junction.Three kinds of absorber pipe layouts including serpentine pipe,unidirectional spiral pipe and bidirectional spiral pipe were proposed and evaluated with numerical simulation under various working conditions.The results showed that the system exhibited the best thermal behavior at a flow rate of 90 L/h and solar radiation of 800 W/m2and the thermal efficiency can reach 71.5%.Different absorber pipe layouts had little effect on the thermal efficiency and PV average temperature.However,the bidirectional spiral pipe in which the cold and hot flows were alternately arranged can significantly improve the uniformity of PV temperature distribution,and the maximum temperature non-uniformity of PV can be reduced by 37.5%.