Comparative Experiments on a Novel CaCl2-Based Composite Material and Zeolite 13X Inside a Sorption Reactor for Solar Heat Storage
Abstract
A novel sorbent material made of a silica matrix, polymer PEG-600 and 34% by weight of salt hydrate CaCl2 was experimentally studied for thermochemical heat storage applications and compared to zeolite 13X, which is a commonly used material in this field. Four desorption / sorption cycles were carried out using 56 g of composite sorbent in a fixed bed reactor and a dry air flow rate of about 0.14 normal liter s-1. The desorption temperature was set at 130 °C, while sorption was conducted with an air flow at 30 °C and 42% relative humidity. The resulting water sorption capacity is 0.37 g g-1 of dehydrated material, that is twice that obtained with zeolite 13X BFK in the same conditions. The energy density is also improved by 60% compared to zeolite: on average, its value was evaluated to be 782 kJ kg-1 of dehydrated material. Lastly, the sorption kinetics is much slower when using the salt composite. Saturation (𝑃𝑣,𝑜𝑢𝑡/𝑃𝑣,𝑖𝑛 = 0.95) is reached after about 12 h, instead of 2 h 30 with zeolite.