Experimental characterization of a foldable solar cooker with a trapezoidal cooking chamber and adjustable reflectors

In this study, a portable and easy-to-construct solar cooker is presented as an alternative to traditional cooking methods to be used in humanitarian contexts in order to face the issue of humanitarian goods transport and storage. The prototype consists of a trapezoidal cooking chamber and adjustable reflector panels made of inexpensive and readily available materials. The solar cooker was designed to be foldable and transportable by using lightweight materials. In fact, the folded prototype is compact, having a mass of 7 kg. The thermal performance and optical performance of the proposed cooking appliance were evaluated through several experiments conducted without load and with load. The tests were done by using a black pot enclosed with a glass bowl or a plastic bag. During the tests without load, the highest recorded temperature was 149.38 °C. The time needed to bring 1 kg of water from 40 °C until 90 °C was on average 114 min for the glass enclosure tests and 132 min for the plastic enclosure tests. The prototype loaded with 1 kg of glycerin took the same average time of 121 min to reach 105 °C from 40 °C for both glass and plastic enclosure tests. The average values of cooking power, derived using Hottel-Whillier-Bliss formulation with a reference global normal solar irradiance for the clear sky condition, are estimated as 26.0 W for the water tests using the glass enclosure and 31.8 W for the glycerin tests with the glass enclosure. Finally, the cooking performance of the prototype was evaluated by cooking common foods (i.e., tomatoes, rice, potatoes). The average cooking times for tomatoes, rice, and potatoes were always lower than two hours, a value consistent with the cooking times of different box solar cookers.