Improvement of Phase Change Materials in Thermal Energy Storage Systems: A Comprehensive Review

Phase change materials (PCMs) are highly effective in storing and releasing thermal energy during phase transitions, making them critical for thermal energy storage (TES) systems, particularly for renewable energy sources such as solar and wind.They have been reported in energy storage, especially in renewable energy systems such as solar and wind.However, despite their potential, their practical use is limited by low thermal conductivity and slow heat transfer rates.These limitations reduce the efficiency of PCMs in applications requiring rapid thermal responses, such as solar thermal storage and electric vehicle (EV) battery cooling.This review synthesizes and compares recent numerical and experimental studies on PCM enhancement techniques.A significant challenge across these studies is the lack of uniform operating conditions, which complicates the identification of the most effective methods for specific TES applications.The review highlights several strategies to improve PCM performance, including the use of metal foams (MFs), nanoparticles (NPs), and fins.MF has been shown to significantly improve thermal conductivity, increasing it by up to 200% for calcium chloride hexahydrate and 100% for paraffin, while also reducing melting times by 84.9% compared to pure paraffin.NPs, like copper oxide (CuO) and aluminum oxide (Al 2 O 3 ), can enhance thermal conductivity by up to 122% relative to pure PCM.However, higher concentrations of NPs may increase viscosity, which slightly hinders heat transfer.Fins provide a cost-effective method to enhance heat transfer.The addition of fins has been shown to reduce melting times by 65.5% at 3600 seconds, making them an ideal choice for applications where cost is a key consideration.Hybrid systems combining MFs and NPs achieve the greatest performance improvements.For instance, using 3% NPs and a 60% porosity in copper MF increases thermal conductivity by 37.7% and reduces the melting time by 87.03%.Further improvements are observed when using MF with 85-90% porosity and 10-15% NPs, achieving a 90% reduction in melting time.This demonstrates the synergistic effect of combining these two techniques.In conclusion, hybrid methods combining MFs and NPs offer an efficient and cost-effective approach for enhancing PCM performance in TES applications.By integrating the strengths of these techniques, multiple performance limitations can be addressed simultaneously, providing a viable solution for large-scale TES systems.