ABSTRACT
Annually, total consumption of energy in the world reaches to 4.1 × 1020 joules. By twenty-first century, the demand for energy will be triple of what it is now [1]. The increase of greenhouse gases emission and high fuel prices are the main driving forces to seek various sources of renewable energies [2]. Saving of energy in suitable forms that minimize the mismatch between supply and demand is one of the important challenges for researchers. One of the new sources of energy saving is the use of phase change materials (PCMs). PCMs are the latent heat storage materials that can produce high density of energy storage at a constant temperature, which is called phase change temperature. The phase change process can be in the forms of solid-solid, solid-liquid, solid-gas, liquid-gas, and vice versa. The solid-gas and the liquid-gas phase changes have more latent heat, but the high volume change during the phase change process is an important defect. The solid-liquid phase change has lower latent heat, but the lower change in volume during the process attracts more attention for its industrial uses [3].
