Experimental investigation and improvement in heat transfer of paraffin PCM RT58 storage system to take advantage of low peak tariff rates for heat pump applications

This paper reports on an experimental energy storage system, consisting of a longitudinally finned concentric container incorporating 98 kg of RT58 phase change material (PCM) with a melting point of 60 degrees C. The research forms part of a wider study to explore PCMs to take advantage of off-peak electricity tariffs. The experimental study results have been reported using temperature time curves, isotherm plots, trend of heat transfer coefficients based on quantitative amounts of energy charged and discharged from the PCM. Isotherm plots indicated uneven heat distribution and the charge and discharge rates of energy averaged 0.6 and 0.2 kW, respectively, prompting the need to develop a more efficient heat transfer technique to improve charge and discharge rates. Increased average inlet heat transfer fluid temperature from 60.9 to 65.9 degrees C improved heat transfer coefficient by as much as 70% for charging and 11.3% for discharge process.