Heat transfer comparison between branching and non-branching fins in a latent heat energy storage system

Thermal energy from sustainable sources is a growing percentage of the global energy budget, one which requires storage technologies for effective use. For thermal energy, latent heat energy storage systems (LHESSs) offer the potential for significantly improved energy density and quality compared to traditional sensible storage systems. Most materials suitable for use in LHESSs, however, have very low thermal conductivities leading to limited heat transfer rates and requiring advances in heat exchanger design for these systems. Therefore, the first ever experimental study was performed comparing a heat exchanger using bifurcated fins and heat exchangers with straight fins within a shell-and-pipe LHESS. The bifurcated fins transferred less energy than the straight fins during charging tests due to their reduced ability to form convective cells of molten phase change material. During discharge the bifurcated geometry provided a lower but steadier rate of heat transfer, exchanging slightly more energy over an 8-h period than the straight fins. With the additional manufacturing cost required to obtain the bifurcated fins, it was found that their implementation in this shell-and-pipe LHESS offers no energetic nor economic advantages.