New Database on Phase Change Materials for Thermal Energy Storage in Buildings to Help PCM Selection

Abstract

According to the International Energy Agency (IEA) the primary energy production was increased by 49% and CO2 emissions by 43% over the past 20 years. Furthermore, 30 - 40% of total energy consumption in developed countries comes from the private sector (housing and offices). Thermal energy storage (TES) is proposed as one way to improve the gap between energy consumption and energy supply. TES systems can store energy as sensible heat, latent heat or chemical reaction. Phase change materials (PCM) are extensively studied materials for thermal energy storage as latent heat because these materials have high phase change enthalpy in a wide variety of phase change temperature. Nowadays it is quite difficult to have all the reported information about PCM properties, not only the thermophysical ones but other relevant properties, even though there are different compilations. CES Selector is software used in material selection, besides being a materials database it permits to include new materials introducing their properties, as well as to classify them in several groups, to plot the data and combine graphs production with the material selection under the desired criteria. More than 300 substances used as PCM and reported in the literature were introduced in a new database created using CES Selector. Thermophysical properties as melting temperature (°C) and melting enthalpy (kJ·kg-1) have been plotted and PCM selections under different criteria were carried out. This database can be completed in the future with other relevant properties either than thermal such as chemical properties (durability in different media etc), reported density or viscosity at a given temperature or even cost of each material. Analyzing these plots it is observed that some PCM are represented occupying a wide range of a given thermophysical property. This is the case of CaCl2·6H2O: data came from 7 sources and the occupied area in the plot is the highest one from all the PCM reported. On the other hand, some other PCM are represented with smaller dots associated with a lower dispersion in the property values and this size may possibly be attributed to different reasons: scarce sources for experimental data or low dispersion among several experimental reported values. These results emphasize that there is a lack of standardization for the measurement of the PCM thermophysical properties.