The connection between the heat storage capability of PCM as a material property and their performance in real scale applications

- How to do a correct measurement of h(T) has been investigated thoroughly.
- Discussion about the observed effects and their origins when measuring thermal properties.
- To identify the conditions that affects reproducibility and transferability.
- h(T) changes at a single temperature, but this is not happening under experimental conditions.
- The main origins for getting different results have been identified and strategies are given.

Using phase change materials (PCM) for Thermal Energy Storage, the most important material property is their heat storage capability, usually given as h(T). Ideally, h(T) changes suddenly at a single temperature. However, many PCM change phase in a temperature range and show hysteresis. In addition, experience shows that even measurements with the same device on the same material can give different results when the heating rate, the amount of sample mass or the equipment device are varied. The question thus arises how to deal with different h(T) results when trying to predict the performance of a real scale application. This paper identifies the main origins of these effects and gives strategies for dealing with them.