Numerical investigation of Scheffler parabolic solar ovens: thermal performance and bread baking application

Abstract

• Comparative analysis of the performance of traditional parabolic solar cookers and a Scheffler-type parabolic cooker. • Baking bread using a solar oven with a Scheffler reflector. • Variations in Temperature and Water Content During Bread Baking in a Solar Oven. • Finite Element Model for Bread Baking using a Scheffler Parabolic Reflector. Access to clean cooking has advanced in recent years with the development of solar thermal technologies; however, the thermal performance and scalability of advanced solar concentrators for community-scale food processing remain insufficiently assessed. This study proposes a concise two-part methodological framework to analyze the optical and thermal performance of parabolic solar cookers and their application to solar bread baking. In the first part, a finite-element model is validated by comparing simulated results with published experimental measurements for two configurations: a Scheffler concentrator and a segmented conventional parabolic dish. The validated model is then extended to perform a comparative analysis of four parabolic concentrator geometries. The results show that the Scheffler cooker exhibits the highest performance ( F 1 = 0.30 (m 2 ·K)/W, F 2 = 0.85, P SC = 434 W, η op = 0.899) and the shortest cooking time among the four parabolic configurations, all remaining faster than box- or panel-type cookers, due to its shading-free geometry and fixed-focus quasi-planar reflector. In the second part, a coupled heat- and mass-transfer model is implemented to simulate solar bread baking in a solar oven equipped with a Scheffler-type reflector. The model incorporates the thermophysical properties of the dough and predicts both temperature and moisture evolution during baking. For a batch of 32 cylindrical loaves (16 cm radius, 5 cm height; total mass 15 kg), the oven reaches 90 °C in 110 minutes using a 3.914 m2 reflector, and in 85 minutes with a 5.324 m2 reflector. The findings confirm the system’s efficiency under solar-noon conditions and underscore its strong potential as a sustainable cooking solution for rural and developing regions.