Energy, exergy and economic analysis of ceramic foam-enhanced molten salt as phase change material for medium- and high-temperature thermal energy storage

Abstract

This study carried out comprehensive energy, exergy and economic analysis of ceramic foam/molten salt composite phase change material (CPCM) for use in medium- and high-temperature thermal energy storage systems. Ceramic foams with various pore configurations were fabricated and integrated with molten salt. A visualised experimental setup was built and a numerical model was developed to experimentally and numerically investigate the melting performance of ceramic foam-enhanced molten salt. It is found that compared to pure PCM, the melting rate of 10 PPI (Pores Per Inch), 15 PPI and 20 PPI CPCMs is increased by 51.5%, 51.5% and 39.4% respectively. Moreover, the porosity has a more remarkable effect on the enhancement in melting rate than pore density. The total stored energy is slightly decreased but the energy storage rate is greatly improved. The energy storage rate of CPCM with 0.80 porosity is increased by 73.2%. Exergy analysis indicates that the exergy efficiency of all CPCMs is more than 50% higher than that of pure PCM. At the benchmark price of ceramic foam, CPCMs with 0.80 and 0.85 porosities are economically feasible. The effective thermal energy stored per unit time and unit price can be increased by up to 58.0% and CPCMs with low porosity are more cost-effective. This study provides a comprehensive evaluation of ceramic foam in terms of enhancing the heat transfer performance of molten salt for the potential large-scale applications in medium- and high-temperature thermal energy storage.