Designing and manufacturing a solar heater similar to a cake mold (CM)

Abstract

This study presents the design, fabrication, and experimental evaluation of a novel, low-cost solar water heater utilizing a compact cake mold (CM) geometry. The configuration enhances solar absorption by increasing the heat-transfer pipe's effective length. The system integrates copper tubing along the mold structure, optimized reflective mirrors to concentrate radiation, a transparent glass cover to reduce thermal losses, and an insulated 60L thermal storage tank. Testing was conducted in Basra, Iraq, from January 2017 to May 2019 across diverse climate conditions. At a constant mass flow rate of 170 ml/min, the maximum outlet temperature reached 97°C under 1024 W/m² solar intensity, and up to 70°C during cloudy conditions. The collector achieved an average experimental thermal efficiency of 81.6%, which was validated through theoretical modeling of solar angles, buoyancy-driven flow, and heat transfer. Economic analysis demonstrates that the system can be manufactured cheaply using local materials, making it a viable alternative to conventional flat plate collectors for residential and remote applications in high-irradiation regions.