Design and measured performance of a plane reflector augmented box-type solar-energy cooker

The design philosophy, construction and measured performances of a plane-reflector augmented box-type solar-energy cooker are presented. The experimental solar cooker consists of an aluminum plate absorber painted matt black and a double-glazed lid. The bottom and sides are lagged with fibreglass wool insulator. The reflector consists of a wooden-framed commercially available specular plane mirror which is sized to form a cover for the box when not in use. Provision is made for four cooking vessels, each capable of holding upto 1 kg of water. Results of thermal performance tests show stagnation absorber plate temperatures of 138°C and 119°C for the cooker with and without the plane reflector in place respectively. Boiling times of 60 min (3600 s) and 70 min (4200 s) for 1 kg of water, for the cooker with and without the plane reflector in place, respectively, were recorded. The solar cooker performance has been rated using the first figure of merit (F 1) on the no-load test and the second figure of merit (F 2) on the sensible heat tests. Predicted water boiling times using the two figures of merit compared favourably with measured values. The performance of the cooker with the plane reflector in place was improved tremendously compared to that without the reflector in place.