Experimental analysis of a zeolite heat storage system

Abstract

Solar energy supply does not always match demand and it is therefore necessary to investigate efficient ways of storing thermal energy. Sorption based thermochemical heat storage provides high energy densities as well as an exceptional advantage in minimizing losses when utilised for long-term heat storage. To commercialize sorption storage systems, additional research and development is required to validate numerical models to allow for accurate design calculations. A lab-scale prototype was developed to analyse the thermal storage characteristics of zeolite 13X in an open (non-pressurised) sorption system. The experiments that were conducted involved a reversible reaction between a solid (zeolite 13X) and a gas (water vapour in air). Two charging (desorption) processes were conducted, where the zeolite pellets were dehydrated by hot air at 130 oC and 200 oC respectively. During the two corresponding discharging (adsorption) tests, humidified ambient air was supplied to the reactor bed, which rehydrated the zeolite particles, resulting in a temperature increase of between 28- 38 oC. The results obtained from this experimental work will be used to inform the design of a sorption heat storage system for a solar thermal plant.