Analysis of Different Heat Transfer Mechanisms Portions during Traditional Flatbreads Baking to Improve Quality of Breads and Reducing Fuel Consumption

Accurate cognition of the portions of different mechanisms of heat transfer during the baking process is important and it can introduce useful solutions to improve quality of breads and reduce energy (fuel) consumption of oven. In this study, by experimental measurements and mathematical equations, portions of different mechanisms of heat transfer during the baking process of traditional hand-baking flatbreads are calculated. Then, based on results optimization is carried out for ovens. The optimization includes modification of geometry of oven, control of excess air, and improvement of thermo-physical and radiant properties of oven walls. The obtained results showed that in Sangak and Barbari bakeries portions of convection heat transfer mechanism (natural and forced convection) and volume radiation are negligible against of conduction and surface radiation mechanisms. The results of thermal diffusivity and emissivity optimization illustrated that fuel consumption for Sangak, Barbari and Taftun bakeries can be reduced about 26%, 28% and 8% respectively. Also in optimal conditions for all bakeries, reduction of excess air from current values to 10% is leading to reduction of more than 90% of excess air losses.