| Summary: | Water use as a heat storage material in solar water heaters (SWH) has disadvantages, including its low energy density, which requires a large volume of thermal energy storage. Phase-change material (PCM) is a latent type of heat storage material that has the advantage of being a high energy density. Therefore, PCM is quite interesting to be applied to SWH systems. In the operation of SWH, it is necessary to know the characteristics of hot water usage. This paper aimed to determine the characteristics of a continuous and gradual discharging method on SWH that applies PCM. This study used a thermosyphon type of SWH. The tank was placed horizontally on the top side of the collector with a volume of 60 liters. Twenty-four cylindrical capsules containing paraffin wax were inserted into the tank. Thermocouples were installed on the waterside and the PCM side. Continuous and gradual methods were carried out in the discharging experiment. Experiments using a continuous discharging method given information that water temperature decrease continuously in the tank. Experiments with a gradual discharging method showed PCM's contribution, which can transfer thermal energy to the water. The gradual discharging method explained that the SWH system produced hot water that can be used for bathing as many as five people every day with water temperatures of 45 °C at an average solar radiation intensity of 514.89 W/m2. The use of PCM makes a positive contribution to the thermal energy storage in the tank. © 2022 American Institute of Physics Inc.. All rights reserved.
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