The potential of arc-shaped fins for expedited solidification in triplex-tube latent heat storage: Parametric investigation

Phase change materials (PCMs) enable efficient thermal energy storage (TES) but suffer from poor thermal response. This study introduces and optimizes a novel arc-shaped fin configuration to improve heat recovery during PCM solidification in a horizontal triplex-tube TES unit. The effects of fin base length and inter-fin angle on solidification time, temperature distribution, and heat recovery rate are systematically analyzed. An asymmetric base length of 15 mm for internal fins and 10 mm for external fins substantially expedites solidification. This is attributed to enhanced heat conduction from the larger surface area of longer internal fins and increased natural convection from reduced external fin blockage. Furthermore, compact 0 degrees inter-fin angles create extensive fin-free zones that encourage convection. The optimized arc-shaped fins reduce solidification time by about 75 % and elevate heat recovery rate by 284 % versus no fins. They also significantly outperform conventional longitudinal fins, which only achieved 47 % faster solidification and 80 % greater heat recovery over no fins. This highlights the profoundly favorable solidification enhancement and temperature uniformity offered by properly designed arc-shaped fins.