Single and Multi-phase Change Materials Used in Cooling Systems

The use of refrigerators and air conditioners has been increasing in domestic and commercial buildings constantly over the last century, resulting in a significant increase in energy demand. Thermal energy storage (TES) system may be able to reduce energy and temperature fluctuations and enhance the overall need or the performance of cooling systems. Application of phase change materials (PCMs) in TES systems can be beneficial for balancing supply and demand in energy, minimizing and shifting the peak cooling loads, reducing the temperature fluctuations. This article presents an overview of TES systems incorporating PCMs for air conditioning, refrigerators, and freezers. Literature shows different ways to incorporate PCMs in air conditioning systems. PCM use in compartments and evaporators and PCM as a heat storage medium in condensers prevail in the present review. Organic-based PCMs are the most widely used materials in air conditioning systems. Then, this study compares the applications of single and multi-PCMs in cooling systems. The results showed that, compared to a single PCM configuration, multi-PCM configurations improved heat transfer rates, reduced the gap between peak and off-peak loads of electricity demand, and shifted electricity consumption from peak to off-peak times. In conclusion, this study indicates that the potential for using PCM in refrigerators and air conditioners still requires further investigation on improving the PCMs properties and the PCM container materials and developing analytical methods for accurately predicting the PCM behavior.