Experimental investigation of thermal performance of flat and v-corrugated plate solar air heaters with and without PCM as thermal energy storage

The purpose of this research is to carry out an experimental investigation of flat and v-corrugated plate solar air heaters with built-in PCM as thermal energy storage material. The integrated solar air heater with paraffin wax as PCM was designed and tested under prevailing weather conditions of Tanta city (30 degrees 43'N, 31 degrees E), Egypt. The parameters affecting the thermal performance of the flat and v-corrugated plate solar air heater were presented with and without PCM. These parameters include solar radiation, the temperature difference of air across the heater, convective heat transfer coefficient between the absorber plate and the flowing air, instantaneous thermal efficiency, daily average efficiency and the PCM freezing time. The thermal performance parameters were studied when the mass flow rates were 0.062, 0.028 and 0.009 kg/s. The effect of changing the thickness of PCM below the absorber plate was also studied. From the experimental results, it was found that when using the PCM, the outlet temperature of the v-corrugated plate solar air heater was higher than ambient temperature by 1.5-7.2 degrees C during 3.5 h after sunset compared with 1-5.5 degrees C during 2.5 h after sunset for flat plate solar air heater when the mass flow rate was 0.062 kg/s. It was also concluded that the daily efficiency of the v-corrugated solar heater using PCM was 12% higher than the corresponding ones without using the PCM and it was also 15% and 21.3% higher than the corresponding values when the flat plate was used with and without PCM when the mass flow rate was 0.062 kg/s, respectively. (C) 2016 Elsevier Ltd. All rights reserved.