Commercially focused strategies to enhance PCM thermal conductivity in latent thermal energy storage systems

Abstract

It is widely recognized among specialists that PCMs (Phase Change Materials) typically have low thermal conductivity, which significantly restricts their commercial use. This study presents alternative, low-cost, yet effective approaches to enhance the average thermal conductivity of a PCM system (a commercially available paraffin wax with a phase change temperature around 40 °C) intended for thermal energy storage. The system contains 600 g of PCM within an annular space around an inner tube, through which heat is either added to or removed from the PCM. Experiments were conducted to assess the effects of water flow rate and temperature, used as the heat transfer fluid, on the system's performance. The flow rate was varied from 2 to 8 L/min, and the temperature was set between 45 and 55 °C. We tested three types of aluminum-based thermal enhancers: a commercial metal foam, a wire mesh, and irregular aluminum flakes (chips) produced as waste from machining processes. The PCM-only sample required the longest time for both charging and discharging, while the PCM with metal foam had the shortest times. The intermediate solutions, using chips and wire mesh, showed moderate phase change times. To evaluate the economic feasibility, we introduced a performance metric based on cost per phase change rate, showing that these two affordable thermal conductivity enhancers could play a vital role in promoting the broader application of latent thermal energy storage technology across various fields.