Low Cost Domestic Solar Water Heater with Parabolic Dish Concentrator: Thermal Analysis, Design and Performance Evaluation

The high cost of solar thermal collectors and installation constraints highlight the need for a simple, affordable, and urban-friendly domestic solar water heater (DSWH)—specifically, based on a parabolic dish concentrator (PDC). This study aims to investigate the thermal-hydraulic system of such a DSWH, determine its parameters, and identify an effective control method to ensure high thermal performance. The primary research method involved mathematical modeling of the thermal-hydraulic processes within a solar thermal receiver, heat storage tank, and connecting piping. Given the specific nature of the processes, different modeling approaches—using both lumped and distributed parameters—were applied to each component under two water-transfer control modes: continuous and periodic. Periodic pumping demonstrated significantly better thermal efficiency across a wide range of fluctuating operating conditions. A prototype of the DSWH was constructed, and its testing identified key areas for design improvement. Finally, the annual thermal output of the PDC-based DSWH was compared with that of a conventional DSWH utilizing two flat-plate solar collectors. Despite having an aperture area less than half that of the two solar collectors, the experimental DSWH provides a greater total volume of warm water than a traditional DSWH, as well as significantly better uniformity of water heating throughout the year. The results confirm the viability of developing, manufacturing, and using a simple, low-cost DSWH design incorporating a PDC.