Bench-Scale Demonstration Test and Design of a Moving Bed Counter-Flow Heat Charger for Unused Energy from a Sugar Mill

To achieve a decarbonized society and sustainable goals, there is an urgent need to expand the use of industrial unused heat and renewable energy. In order to expand the flexibility of utilization of unused heat, it is necessary to devel-op a thermal energy storage and transport system that can resolve the spatiotemporal gap between generating unused heat and heat demand. In this study, we focused on the heat storage side in the system and devised a counter-flow type moving bed reactor that stores unused heat continuously. A demonstration test on a scale of about 1/400 of the full scale under actual conditions at a sugar mill was conducted, and a full-scale model was designed by a validated numerical model. In the test, 0.75 kW of continuous heat storage was successfully demonstrated. A numerical model was developed to predict the performance of the heat storage system, and it was found that the test results could be simulated by a steady-state one-dimensional model considering the radial effective thermal conductivity of the packed bed. A full-scale storage system was designed using the validated steady-state one-dimensional numerical model. The design parameters were organized, and a method was established to determine the variable parameters, i.e., packing layer height and inlet gas flow rate, to minimize the auxiliary power required for heat storage at each zeolite flow rate.