Impact of sun tracking on the performance of a high concentration ratio box solar cooker

Influence of manual sun tracking on the thermal performance of a box solar cooker with a high concentration ratio was investigated. It was found convenient to fit the measured temperature of the cooking chamber in a test without load and load temperature with both first- and second-order exponential polynomial curves to determine the maximum values of both temperatures and the reference heating time for bringing the cooking chamber and load from an initial to a final reference temperature under 1000 W m−2 of solar irradiance and 30 °C of ambient temperature. For tests without load, the results of the two regressions showed good agreement, while the effect of tracking was negligible. For tests with silicone oil, only the second-order exponential polynomial was able to describe the measurements accurately. It was found that the reference heating time needed to bring silicone oil from 30 to 240 °C was estimated to be 2.4 h by applying perfect tracking. Instead, it was 2%, 11%, and 36% higher for tracking time intervals of 5 min, 15 min, and 30 min, respectively. This analysis is important for understanding how to use this solar cooker effectively in practice.