Development and Performance Analyses of Thermal Energy Storage System using Shea Butter as Phase Change Material

Abstract

The focus of this study is to experimentally determine the performance of latent heat thermal energy storage using shea butter as a phase change material (PCM) in a heat exchanger (shell and tube). This involved determination of the thermo-physical properties of the PCM, design of a suitable heat exchanger (shell and tube) to serve as the storage system where the shell (mild steel) will contain the PCM in direct contact with the tube (copper), construction of the system based on the designed parameters and performance evaluation of the system through experiments (water used as heat transfer fluid), energy and exergy analyses. DSC analysis reveals a transition temperature in the range 31.260C to 40.160C and latent heat of 50.36kJ/kg. These values are low compared to other commonly used PCMs such as paraffin wax (1000C, 140kJ/kg), stearic acid (55.80C, 160kJ/kg) and Acetamide (820C, 263kJ/kg). The system is designed to heat water from 250C to 350C, however the maximum temperature achieved is 310C. Melting and solidification curves shows non uniform melting and solidification of the PCM during charging and discharging operations. The overall performance of the system based on energy and exergy analyses revealed satisfactory performance with minimum energy efficiency of 59.04% and maximum of 89.88% and minimum exergy efficiency of 20.37% and 30.44% maximum.