摘要
Energy is essential for every human activity for more comfortable life but also consumes more natural resources. In order to control human comfort, temperature usually required when the differences in temperature swing between indoor and outdoor temperatures. PCMs （phase change materials） are the high latent heat materials which can be used in building materials for energy conservation purpose. PCMs can store thermal energy and also can prevent heat to pass through temperature control areas. Paraffin has been used as PCMs are absorbed into the pore of fly ash as paraffin/fly-ash composite and mixed into the buildings materials. Paraffin is an organic material with high melting point （-59℃）, and nonflammable materials therefore paraffin can be used as the building materials for the function of PCMs for energy saving purposes. Composite PCMs can be prepared by vacuum impregnation process. Paraffin in liquid form will be impregnated into the pore of fly ash by vacuum capillary force to form paraffin/fly ash composite PCMs. Vacuum impregnation pressures, vacuum times, impregnation times of liquid paraffin in fly ash pores and temperatures for melting the solid paraffin into the liquid form are all affect on the thermal properties of paraffin/fly ash composite PCMs. Paraffin or PCMs impregnation are also relate to the physical property including the fractal dimensions of the pores of the fly ash particles and paraffin/fly ash composite PCMs. The fractal dimensions of the pore of fly ash and paraffin/fiy ash composites PCMs are between the values of 1.0 and 2.0. Fractal dimensions of paraffin/fly-ash composite PCMs have the same trend as the thermal properties for heat capacity and latent heat of melting. These fractal dimensions technique is a novel method to measure physical property of building material related to latent heat and heat capacity.
