PV/T集热器冷却技术的研究进展

Research Progress of PV/T Collector Cooling Technology

太阳能光伏光热一体化组件由光伏与光热两个部分组成,其中光伏面板能够提供各领域所需电能.由于光伏温度的升高会影响光伏组件的电效率及电池寿命,所以在光伏系统中加入光热部分,将多余的热量转移并加以利用,进而提高太阳能的综合利用效率.以液体和空气作为传热介质的太阳能光伏光热(PV/T)系统是通过对流的方式将光伏进行冷却,为了提高工作流体的均温性及系统在高电池温度峰值下的稳定性,可在水基PV/T中增加纳米颗粒.为了提高纳米流体的稳定性及热导率,可以使用混合纳米流体或者在单一纳米流体中加入相变材料(PCM).通过PCM进行冷却的PV/T系统是通过传导的方式将光伏进行冷却,可通过调整PCM的厚度实现控制温度的下降速率,或者在PCM内填充纳米颗粒增大组件的导热系数,以提高PV/T系统的热/电效率.通过总结目前相关的研究可知,PV/T集热器冷却技术还需深入研究的方面包括:混合纳米流体颗粒的浓度和工作温度对其热导率的影响、两相流传热理论及粒子间相互作用对纳米流体稳定性的影响、外界影响因素的波动对PV/T系统影响的动态理论研究、PCM自身特性对充放热速率和循环使用的影响、考虑经济性的热管数量对PV/T系统性能的影响以及适用于太阳能PV/T热泵系统的动态预测.

Solar photovoltaic photothermal integrated module is composed of photovoltaic and solar thermal two parts,of which photovoltaic panels can provide the required electric energy in various fields,because the increase of photovoltaic temperature will affect the electrical efficiency and battery life of photovoltaic modules,so add solar thermal part in the photovoltaic system,the excess heat is transferred and utilized,thereby improving the comprehensive utilization efficiency of solar energy.Solar photovoltaic photothermal(PV/T)systems that use liquid and air as heat transfer media are convection to cool photovoltaics,and nanoparticles can be added to water-based PV/T to improve the temperature uniformity of the working fluid and the stability of the system at high cell temperature peaks.In order to improve the stability and thermal conductivity of nanofluids,hybrid nanofluids can be used or phase change materials can be added to a single nanofluid.PV/T systems cooled by phase change materials(PCM)are cooled by conduction,and the temperature drop rate can be controlled by adjusting the thickness of the PCM,or the thermal conductivity of the components can be increased by filling the PCM with nanoparticles,so as to improve the thermal/electrical efficiency of the PV/T system.Through the analysis,the directions of further research can be carried out as follows:the influence of the concentration and working temperature of mixed nanofluidic particles on their thermal conductivity,the theory of two-phase flow heat transfer and the influence of particle interaction on the stability of nanofluids,the dynamic theoretical study of the influence of fluctuations of external influencing factors on PV/T systems,the influence of PCM itself on the charging and releasing heat rate and cycling time,the influence of the number of heat pipes considering economy on the performance of PV/T systems,and the dynamic prediction of solar PV/T heat pump systems.