In pan bread production, convective and radiant heat is absorbed by the pan, which also serves as the mechanism to conduct heat to the product. dT/dx is the temperature gradient between to points (in the case of pan bread baking, these two points can be the pan and dough).A is the area of the pan or product through heat flows (m2).k is the thermal conductivity of air, pan or dough (in W/m.According to Fourier’s law, the heat flux by conduction is deduced from the following formula: 1,2 Or, at the interface between the oven hearth and the dough piece when the product is placed directly onto the hearth. Transfer of heat to a dough or batter by conduction occurs at the dough surface level in a baking pan (or tin). The h coefficient depends on oven conditions, product geometry and air properties, mainly: h is the convective heat transfer coefficient (in W/m2.Heat flux by convection can be calculated as: 1,2 the temperature difference between hot air and product). 3įorced convection devices recirculate the air and/or combustion gases surrounding the product to provide driving force to maintain as high heat transfer as possible (i.e. For example, the absence of of fans, blowers and other air-movement devices like color-aiders. Natural or forced convection is a function of flow characteristics. It represents the heat transferred by means of a moving fluid, like hot air in the baking chamber. ε is the emissivity of the object (typically between 0 and 1).σ is the Stefan–Boltzmann constant, 5.67 x 10-8 W/(m2.The energy flux (Q) depends mainly on the temperature of the object.Īccording to Stefan–Boltzmann’s law, heat flux radiation to the dough is proportional to the difference between baking chamber wall temperature (TW) to the power of four and dough temperature (TD) to the power of four: 1,2 Heating elements and oven walls emit energy in the form of electromagnetic waves.

It occurs between two surfaces or materials at different temperatures by the emission of energy in the form of electromagnetic waves and subsequent absorption. Analyzing and controlling these aspects are fundamental to product quality. This information helps explain why one oven bakes differently from another. Knowing the total heat experienced by the product, and the contribution of individual heat fluxes is critical to understanding finished product characteristics. Therefore, they’ll have their own heat flux profile. It is important to recognize that different products have their unique mix of heat flux components.

Heat flux equation