Phase change material (PCM) absorbs or releases a large amount of latent heat when it melts from a solid into a liquid or crystallizes from a liquid into a solid in material specific temperature ranges. The latent heat absorption or latent heat release of PCM is measured, for instance, by utilizing ASTM Standard Test Method E 794. When the PCM is applied to a carrier matrix, its absorption and release of latent heat regulates the heat flux through the matrix material.
In order to quantify this heat flux regulation, a new a measuring method had to be developed. This measuring method is based on a transient measuring principle in which the latent heat absorption/latent heat release of the PCM embedded in the matrix material is transferred into an insulation term, called “adaptive thermal insulation”. This adaptive thermal insulation of the PCM acts in addition to the basic thermal insulation of the matrix material. In the measuring procedure the basic thermal insulation of the matrix material and the adaptive thermal insulation of the PCM are determined in separate steps. This procedure makes direct comparisons between matrix materials with and without PCM treatment possible and quantifies the thermal performance contribution of the PCM integrated in a given matrix material.
In order to determine how long the thermal effects generated by the PCM application in a certain product will last, a modelling procedure has been developed based on these measurements. By utilizing this modelling procedure, calculations of heat transfers and heat balances under various conditions the product with the PCM treatment is used are carried out. In this way, it can be determined if, for instance, the PCM quantity applied to the matrix material is sufficient enough to provide the desired thermal effects. Furthermore, the calculations are used to quantify the improvement in the thermal performance of a given product by the PCM application.
In the presentation, the test method will be introduced, examples of test results will be presented and the modelling procedure will be discussed.