Thermal performance investigation of concentric and eccentric shell and tube heat exchangers with different fin configurations containing phase change material

The aim of this study is to evaluate the combined effect of fin configuration and eccentricity of heat transfer tube on melting behavior of phase change material (PCM) inside the shell and tube heat exchanger (HX). Two unfinned HXs with concentric and eccentric heat transfer tubes and six other HXs with different arrangements of straight and bifurcated fins were fabricated while the total fin mass was kept constant. The shells of heat exchangers were made of transparent Plexiglas and the melting process was photographed to enable the analysis of the solid-liquid interface evolution. Experimental findings of the unfinned HXs showed that applying the eccentric tube HX leads to a 54% reduction in melting time compared to the concentric tube HX. Among all the cases considered, bifurcated fin configuration outperforms the straight fin configuration. The maximum melting time reduction compared to the HX with concentric unfinned tube was 85% obtained by eccentric tube HX with a long upper bifurcated fin and a short lower straight fin. Transient numerical simulations using a control volume approach were carried out for three tube wall temperatures of 75, 85 and 95 °C. Numerical results showed that the bifurcations increase the total heat transfer rate while the convective heat transfer coefficient decreases.