Application of CFD for the analysis of medium-scale LHTS for district heating

Abstract

The Finite Volume method has been used to analyse the behaviour of a medium-scale latent heat thermal storage system. The shell-and-tube storage system is filled with phase change material (RT100) in the shell and heat transfer fluid flows through the tube of the storage system. Normally, Organic PCM has low thermal conductivity. Numerous studies from the literature have been reviewed which discuss the enhancement of thermal conductivity of the PCM. The addition of graphite in the PCM is considered an effective way of improving the thermal conductivity of PCM. In this thesis, the major focus is to analyse the performance of the storage system with variation in the volumetric content of graphite in RT100. The four cases of a storage system having 0 %, 7,5 %, 15 %, and 30 % volumetric content of graphite in RT100 was investigated. The purpose of designing the graphite-paraffin-based LHTS was to transfer the heat from district heating to the building heating network. The solidification/melting fraction and variation of the temperature inside PCM and fluid at different time-period have been presented. The heat transfer rate and total heat extracted by fluid from the PCM have been calculated. The results show that the heat transfer rate becomes many folds of the pure PCM with increasing the amount of graphite in the PCM. The timewise variation of outlet heat transfer fluid has been shown for different Reynolds numbers and Stefan number.