LAUSR

Abstract In this study, an experimental and numerical performance analysis of a new solar water heating thermosyphon design is proposed. The heat losses during the night (off-sunshine hours) are studied by investigating the efficacy of including the phase change materials in the cylindrical storage tank to enhance the utilized fraction of solar energy. The thermal performance of the heating system with a cylindrical thermosiphon tank with phase change materials is experimentally and numerically investigated. The experimental setup consisted of a flat plate solar collector of an area of ​​2 m2 and a storage tank of a volume of 280 liters. The numerical model of the system is simulated by TRNSYS and FLUENT Software and it is validated by experimental and published data. It was found that with the new design, the water temperature inside the tank remains approximately constant at around 35 °C and 25 °C overnight on a summer and winter day, respectively. In the new design, the water temperature was maintained at a value almost double that of the classic one with a maximum value of 67 °C and 55 °C in July and January, respectively. The payback period of the new system estimated by the economic study was 7.39 years with a net present value of $4265 over its lifetime. The energy savings in different zones in Tunisia was found to be in the range of 60–75%, depending on the intensity of the solar radiation.