Enhancing PCM melting in a triple tube heat exchanger by utilizing innovative fins configurations

Using phase-change materials (PCMs) for latent heat thermal energy storage holds great potential for addressing the mismatch between energy supply and demand. However, a key drawback in utilizing PCMs in thermal energy storage is their poor thermal conductivities, leading to prolonged energy storage and discharge durations. This study aims to enhance the thermal performance of PCMs by introducing an innovative fin shape in a triple tube heat exchanger to reduce energy storage time. Three types of extended surfaces (fins) in a triple tube heat exchanger (TTHX) were examined through numerical simulations. These fins, comprising longitudinal, tee, and plus fins, were affixed to the outer surface of the inner heat transfer fluid tube. The simulations employed comprehensive two-dimensional numerical models encompassing conduction and convection heat transfer techniques. Various design parameters, such as fin size, shape, and quantity, were systematically investigated. The findings revealed a notable enhancement in PCM thermal performance when employing the plus fins shape compared to longitudinal and tee fin configurations. Specifically, the plus fins demonstrated the shortest total melting time in comparison with the longitudinal and tee fins. Substituting longitudinal fins with plus fins resulted in a roughly 22% reduction in total melting time. The findings revealed that augmenting the number of plus fins from 4 to 6 resulted in a decrease in the overall melting duration. Furthermore, the examination suggested that elongating the fins led to a reduction in the total melting time. Specifically, when the length of the plus fins was extended from 25 to 42 mm, the total phase-change material (PCM) melting time decreased by around 33%. The primary inference drawn from the study is that the use of plus fins expedites the PCM melting process in comparison with the utilization of conventional longitudinal fins.