Optimisation du processus de chauffage et de cuisson dans un four à pain à combustible solide : étude théorique et expérimentale

Abstract

In this work, we propose a mathematical model describing thermal behavior, and heating process optimization of solid fuel bread ovens. Numerical simulation leads to tem perature pro les inside the oven. The design and implementation of an operating prototype permits us to obtain, with type K thermocouples, experimental temperature pro les in the set points indicated. There is a good agreement between the experimental results and those obtained from the numerical simulation of the proposed model. A permanent temperature value of 220◦C is reached in the baking chamber. It is obtained that the energy e ciency of the oven is 49%. Making use of the objective gain function, it is found that the optimal parameters of the oven are the following : 50W, as optimum operating value of electric power blower; 3.2m2, as optimum operating value of total surface of baking chamber; and, 0.67 as optimum operating value of lling factor between the heating chamber and the ba king chamber.The mathematical model describing our baking model is solved by the nite di erences method. Using a functional data acquisition device, we obtained the evolution of temperatures at indicated points in the bread during the entire baking process. The use of the results obtained from the model allowed us to have, for a temperature in the baking chamber of 220◦C, a minimum baking time of 1600s, corresponding to a temperature of 94◦C in the center of bread and satisfying quality constraints such as gelatinization degree equal to 1.0, Browning equal to 30, for the Kumba bread. The simulated energy studies showed that a value of 600kJ (400kJ/kg) is required to bake campaign (Kumba) bread, and there was a sign cant impact of the heart during the baking process. During baking process, the dough received mostly radiative heat ux (about 61%). The conductive heat transfer from the heart had 23% of the total contribution. The convec-tive heat transfer was always under 17% of the total heat ux.