Heat transfer performance analysis of phase change material-based latent heat storage unit based on river water source

Water energy is a clean, green, and renewable energy. Phase change material (PCM) has great potential for energy storage and energy saving applications. Utilizing the river water flow to charge the energy into PCMbased latent heat storage (LHS) unit is a new attempt for energy storage. To analyze the feasibility of this novel energy storage method, a coupling model of the PCM-based LHS unit and river water flow was developed in this study. Then, the thermal performance of the PCM-based LHS unit within the river water under different working conditions were investigated. The results show that the proposed energy storage method is feasible. Modifying the geometry sizes (GS) of the unit can affect the liquid fraction and full solidification time variations of the unit. GS-4 with 15 cm x 60 cm is an optimum geometry size of the unit in the current study. A higher water flow inlet velocity can accelerate the reductions of the liquid fraction and PCM temperature. The full solidification time reduces by 13.6 % as the water flow inlet velocity rises from 0.02 to 2 m/s. Arranging fins inside the PCM-based LHS unit is an effective method to enhance the heat transfer behavior of the unit within the river water. The solidification enhancement ratio can reach 77.3 % when the number of fins rises from 0 to 7. For the same total volume of fins, the unit with thin and closely spaced fins (i.e., layout-2 fins) shows highest solidification efficiency. Moreover, thin and closely spaced fins has more superiority for the solidification performance enhancement compared with thick and widely spaced fins. The full solidification time of the unit with layout-2 fins saves by 84.8 % when the water flow temperature ( T w ) reduces by 12 degrees C. For units without fins and with layout-2 fins, the solidification time decreases exponentially with increasing temperature difference between T w and PCM melting temperature.