During the process of binding substances onto the surface of a material (adsorption) and the taking in of a substance through liquids (absorption) heat is released. These processes cause the sorption materials to heat up. The generated thermal energy can be used for heating purposes.
Adsorption heat pumps for instance raise the temperature level of heat in order to cover residential heating demands. A sorption material such as zeolite can be used in adsorption heat pumps as it dries at high temperatures (desorption). The extracted substance, i.e. water vapor, condenses at medium temperatures and provides useful thermal energy. After condensation the water can evaporate at a low temperature due to the low inside pressure. During adsorption of water vapor onto the zeolite heat is again released that can be used.
Solar thermal collectors can supply the heat for evaporation. The temperature level can be close to freezing point. This allows us to extend the useful operation of solar thermal collectors so that they can be used at lower outside temperatures during winter.
