Numerical study of a building integrated photovoltaic-finned phase change material panel under Tunisian climatic conditions.

Abstract

Building-integrated photovoltaic systems' electrical efficiency decreases when their operating temperature increases. To overcome this drawback, the use of the PCM as a passive method to improve the thermal and electrical performances of the system is highly recommended. Yet pure phase change materials are known for low thermal conductivity. Inserting fins in the PCM enhances its thermal conductivity leading therefore to an improvement in the heat transfer rate. The present investigation carried out the optimization of the BIPV-FPCM system to reduce BIPV system temperature at real Tunisian climatic conditions. The best inclination angle of BIPV-FPCM is carried out. Moreover, the suitable depth of the FPCM box is evaluated. BIPV, BIPV-PCM, and BIPV-FPCM systems are compared. In the present thermodynamic work, the fusion and solidification processes of the FPCM were analyzed. In addition, space between successive fin effect, fin length, and position effect on BIPV electrical and thermal performances had been investigated. Interesting findings showed that the decrease in the tilt angle of the module enhances the heat transfer rate in the FPCM due to the improvement of the convection heat transfer rate in the melted PCM. Thirty degrees is found the most optimal tilt angle with respect to the horizontal where the received solar radiation increases with the decrease of the tilt angle from 90° to 30°. Results prove that the best fin number to enhance performances of the BIPV-PCM system is 3 where 6cm is found to be the best PCM box depth. Eventually, fin positioning is so important to improve the rate of heat transfer rate by promoting natural convection in the PCM. Results reveal that "full fins" and "front fins" scenarios are the best cases for improving the melting rate and performances of the BIPV-FPCM system.