Abstract
First ideas of applications design using magnesium (hydro) carbonates mixed with silica gel for day/night and seasonal thermal energy storage are presented. The application implies using solar (or another) heat source for heating up the thermal energy storage (dehydration) unit during daytime or summertime, of which energy can be discharged (hydration) during night-time or winter. The applications can be used in small houses or bigger buildings. Experimental data are presented, determining and analysing kinetics and operating temperatures for the applications. In this paper the focus is on the hydration part of the process, which is the more challenging part, considering conversion and kinetics. Various operating temperatures for both the reactor and the water (storage) tank are tested and the favourable temperatures are presented and discussed. Applications both using ground heat for water vapour generation and using water vapour from indoor air are presented. The thermal energy storage system with mixed nesquehonite (NQ) and silica gel (SG) can use both low (25–50%) and high (75%) relative humidity (RH) air for hydration. The hydration at 40% RH gives a thermal storage capacity of 0.32 MJ/kg while 75% RH gives a capacity of 0.68 MJ/kg.
Highlights
A number of renewable heat sources are not available when needed or do not meet the fluctuating demand for heating
In district heating systems, the seasonal storage possibility lowers the investment costs for plants in use during peak hours, and more thermal solar heating can be introduced to the system
Studies showed that a COP of 1.7–6.8 can be achieved in an open system adsorption thermal energy storage (TES), using a simple electrified humidifier [18]
Summary
A number of renewable heat sources are not available when needed or do not meet the fluctuating demand for heating. The thermal solar heat output great exceeds the heating demand. Solving this problem requires seasonal storage, in the form of thermal energy storage (TES), within affordable boundaries. In district heating systems, the seasonal storage possibility lowers the investment costs for plants in use during peak hours, and more thermal solar heating can be introduced to the system. Using reversible chemical reactions for storage gives the highest energy density. This requires heat sources at 200–1000 ◦ C, which is not applicable in most heating systems [1]. Chemical sorption reactions require lower temperatures and are more energy dense compared to water storage tanks and require temperatures of 50–150 ◦ C in a TES system
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
