Experimental analysis on use of thermal conductivity enhancers (TCEs) for solar chimney applications with energy storage layer

Abstract

Solar chimney has been widely used in industry for solar heating and cooling and in power generation. Their effectiveness can further be increased for building heating/cooling applications if used along with energy storage. However, achieving good heat transfer between energy storage material and air is still a challenge. Several studies have been made on improving the heat transfer by using thermal conductivity enhancers (TCEs). However, no study provides comprehensive analysis on their complex and non-stationary heat transfer characteristics. This paper focuses on the influences of thermal conductivity enhancers (TCEs) on heat transfer performance inside the phase change material (PCM) during the melting and solidification processes for solar chimney application. Four types of TCEs namely vertical fin (VF), horizontal fin (HF), honeycomb structure (HCS) and square cell structure (SCS) have been used in the study. The experimental results show that the VF, HF, HCS and SCS reduce the melting time by 8%, 12%, 14.5% and 16%, respectively compared to the pure PCM sample. It is also being found that the VF and HF with the same volume fraction have different effects on the heat transfer inside the PCM during the melting process proving that the geometry and distribution of fins are very important for the heat transfer enhancement.