PHASE CHANGE MATERIALS

    Phase Change Materials (PCMs) are chemicals (organic and inorganic) that have been engineered to change from solid to liquid and back to solid as a function of specific temperature ranges based on applications.  During these processes, significant amounts of heat are absorbed, stored, and released. 

    In building applications, for example, provided that the PCMs are held in place within building enclosure (envelope) components (i.e., walls, ceiling, roofs, and/or floors), this absorption of heat, its storage, and its release would make it possible for the space cooling and/or space heating demand from the enclosure to be reduced and/or a portion of such load shifted to other times of the day, all the while the building’s indoor air temperature remains relatively stable.

    Other benefits of increasing the thermal mass of the building enclosure via the high latent heat of the PCMs include reducing the short on/off cycling of air conditioners and heaters, which in turn could increase their performance and equipment life.

    Organic PCMs have a low temperature range and low density. Most of them are combustible in nature. Moreover, they have a wider range of melting point plus they are more expensive. Inorganic PCMs are generally hydrated salt based materials. They have a narrower range of melting point and are corrosive.

    Because of their unique structure and characteristics these materials main application is in thermal energy storage. Currently, various investigations are been done to find new ways to incorporate PCMs into the conditioning of buildings or shelters to reduce energy demand (peak reduction) and consumption, and to improve extremely poor load factors inherent in space cooling and space heating applications, and to make air conditioning and heating systems more cost-effective loads to serve.

     At the University of Kansas, we have investigated the use of PCM, both organic and inorganic, in standard frame walls (residential), structural insulated panels (SIPs), and in commercial transportation.  We have used experimental set ups under full weather conditions and under laboratory conditions.  In addition, we have develped transient heat and mass transfer thermal simulation models undergoing phase change.

     Our research has been supported by grants from the National Science Foundation (NSF), the US Department of Transportation (DOT), the California Energy Commission (CEC), the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE), the Energy Research Center (ERC) of the Kansas Geological Survey (KGS), and the University of Kansas (KU) Center for Research (KUCR) through the General Research Fund (GRF).