Collect and Store Solar Thermal Energy in Wall- Cladding System by Using Metal Foam

Abstract

Theoretical and experimental investigations have been adopted to collect and store solar energy in exterior-wall cladding by using metal foam which incorporated with a phase-change material (PCM). Copper square duct was used to heat the air flow inside the duct. Various improvements have been investigated inside and outside the duct to increase the efficiency of heating. Analysis software has been used to simulate all models under investigation. Results show that there is a good agreement between experimental and numerical results and this agreement increases as air velocity increases. The average percentage error for air inside the duct at a velocity of air 1 m/s, 3 m/s and 5 m/s is 8%, 16.5% and 5% respectively. A metal foam has been used to increase the thermal conductivity outside the duct. Also the results depict that the temperature gain for air velocity of 1, 3 and 5 m/s enhanced by about 8, 8.4 and 15.8 %, respectively. Metal foam has also been used outside the duct with both granular hollow sphere duct and vertical cylinders to increase the conduction effect. The enhancement in heat transfer for air velocity of 1, 3 and 5 m/s is found to be 29%, 34% and 35.7 % respectively for this case. Paraffin wax has been also used as a thermal storage media for enhancing the time of thermal discharge. The granular duct, with cylinders and foam, has been found as the best thermal response model (among all models under investigation). A new Nusselt number correlation equation has been developed for the best thermal response model that was found in this work.