Improvement solar box cooker thermal performance using metal fibers

This study presents an experimental investigation aimed at improving the thermal performance of a solar box cooker using metallic fibers and a booster mirror. Three identical cookers were fabricated and tested under two operating conditions: without and with a reflective mirror. Each cooker contained an equal mass of copper, aluminum, or steel fibers distributed around the cooking pot to enhance internal heat transfer. Experiments were conducted under natural solar radiation from 7:00 a.m. to 5:00 p.m., and temperatures were monitored continuously. The cooker containing copper fibers and equipped with a booster mirror achieved the best overall performance, reaching a maximum water temperature of 92.2 °C, and maintaining temperatures above 90 °C for nearly 1 h under peak solar conditions, with a second figure of merit of 0.303, a thermal efficiency of 27.34 %, and an exergy efficiency of 3.07 %. These results confirm the strong influence of copper’s high thermal conductivity on energy absorption and temperature uniformity. The addition of the booster mirror increased heat gain and reduced cooking time by approximately 17 % compared with the non-reflective case. The proposed modification demonstrates that combining conductive enhancement and optical intensification can substantially improve the thermal behavior of solar box cookers, providing an effective and sustainable option for clean energy cooking applications.