ABSTRACT
Phase change materials (pcm) have the ability to store a certain amount of heat without a temperature change, i.e. at the temperature where they change between a liquid and solid. This is of course also the case with water, but a pcm can be chemically composed so that it changes state at a useful temperature, for example 30°C. Thus pcm can store more heat in a given volume within a limited temperature interval than materials that store only sensible heat. Figure IV.8.1 shows this advantage for two salt hydrates in comparison with rock and water.
