| Popis: |
Phase change materials (PCMs), which melt and solidify at close to ambient temperature, offer a great advantage in reducing the energy needed for heating and air-conditioning of buildings. Energy analysis of PCM-integrated buildings strongly depends on the melting point, latent heat, location, and the amount of the PCM incorporated into the building as well as the climatic conditions and the design of the building. Therefore, for building applications, the melting temperature of PCM should lie between 18 C and 27 C depending on the type of building, season, relative humidity, clothing worn, activity levels, and other factors. Materials that have been studied during the last 40 years are hydrated salts, paraffin waxes, fatty acids, eutectics of organic and nonorganic compounds. Hydrated salts have larger energy storage density and higher thermal conductivity but experience supercooling and phase segregation, and hence, their application requires the use of some nucleating and thickening agents. |
