Development of the Ecobalsas Solar Oven Based on a CPC and Cooking Power Estimation for Several Selective Surfaces on the Absorber

Abstract

The Ecobalsas solar oven is presented as an alternative for generate economic savings for families living in dry climates, as it mitigates desertification and reduces the time people spend searching for firewood. It is an oven based on a three-dimensional compound parabolic concentrator that applies non-imaging optics and follows Trombe Meinel curves. The main materials used in its construction are: aluminum specular sheets in sections with high reflectance on the concentrator, a pressure pot (4-liter capacity) in the focal region as absorber, an acrylic panel (3 mm thick) as a cover at the opening area, polyurethane foam with a second waterproof layer as insulator on the exterior of the concentrator, and carbon steel in most of the structure and oven base. It is equipped on a rotative base that allows the hour angle path to be followed over 360° and solar altitude, and has a geometric concentration of about 4.1. Its average cost is $200 USD.Cooking power was determined following the Funk protocol. Merit factors and thermal efficiency were obtained as well [2]. The tests were repeated for four selective surfaces: resinous wood soot called “ocote,” black matte paint mixed with the aforementioned soot, copper oxide, and black matte paint, in order to determine which of these materials provides the best thermal performance and cooking power, thus allowing cooking time to be reduced.