Experimental study on thermal performance of a solar chimney combined with PCM

Abstract

The thermal performance of a PCM based solar chimney is experimentally investigated in this paper. The research is carried out within a laboratory condition with three different heat fluxes of 500W/m2, 600W/m2 and 700W/m2. The results show that for a same charge period of 7h 10min though the PCM does not fully melts in the cases of 600W/m2 and 500W/m2, the absorber surface temperature variations for the three heat fluxes are the same during the phase change transition period. Contrary to the sensible heat discharge period, during the phase change period, the surface temperatures descend very slowly till the latent heat releases completely. The phase change periods are nearly 13h 50min for all cases investigated. The air flow rates vary corresponding to the absorber surface temperature. The air flow rate of 0.04kg/s for the case of 700W/m2 is slightly higher than 0.039kg/s for 600W/m2 and followed by 0.038kg/s for 500W/m2. Unlike to air flow rate, the air outlet average temperature of 19.6°C for the case of 700W/m2 is the lowest amongst three cases, and then followed by 20.1°C for 600W/m2 and 20.5°C for 500W/m2. The peak thermal efficiencies of the solar chimney are observed to be about 80% for all cases at the early ventilation period. 500W/m2 however drives the highest minimum efficiency of 63%.