Numerical investigation of a hybrid latent-sensible thermal energy storage system for low temperature industrial applications

Thermal energy storage (TES) systems are pivotal in enabling application of renewable heat technologies. The present study proposes a hybrid latent-sensible TES system for industrial applications to provide process heat at temperatures between 333 K and 473 K. Numerical analysis of the hybrid TES system was done using ANSYS Fluent (version - 2024 R1), to analyze its techno-economic performance for different proportions of the latent and sensible heat materials (20 %, 40 %, 50 %, 65 % and 80 % of PCM). Heat transfer within the TES system was modeled using a two phase, 1-D Schumann model and a Multi-phase, Eulerian model of Fluent was used in this numerical study. Performance parameters like, storage capacity, charging and discharging rates, efficiency, energy density and capacity cost were used for analysis. Simulation results revealed that, both charging and discharging time increase with higher percentages of PCM in the hybrid TES, with a storage system having 80 % PCM taking 30 min and 73 min more to charge and discharge respectively, than a system with 20 % PCM. This was consistent with the results for efficiency, which indicated that efficiency of the hybrid TES system decreases with higher volume fractions of PCM, even though, the differences are not very significant since all the variations are within 5 %. Energy density was seen to improve from 95 kWh/m 3 to 123 kWh/m 3 while, capacity cost also rises from $40/kWh to almost $70/kWh. • Technical and financial performance of hybrid PCM-sensible systems was analyzed. • Charging/discharging efficiency of systems is affected by PCM percentage in TES tank. • Charging/discharging rates reduced with increased PCM content. • Thermal energy density of hybrid latent-sensible TES system increases with PCM content. • Increased PCM fraction raises the capacity cost of thermal energy stored in the TES systems.