Semiempirical modeling of a traditional wood-fired pizza oven in quasi-steady-state operating conditions

Abstract

Wood-fired ovens are mandatorily used to bake the Neapolitan pizza. Unfortunately, they are still empirically operated. In this work, a pilot-scale wood-fired oven was kept operating in quasi-steady-state conditions. Once the combustion reaction of oak logs had been modeled, the composition of flue gas measured, and the external oven wall and floor temperatures thermographically scanned, it was possible to check for the material and energy balances and, thus, assess that the heat loss rates through flue gas and insulated oven chamber were, respectively, equal to 46% and 26% of the energy supplied by burning firewood. The enthalpy accumulation rate in the internal fire brick oven chamber amounted to about 3.4 kW, this being adequate to keep not only the temperatures of the oven vault and floor practically constant but also to bake one or two pizzas at the same time. Such a rate was predicted by contemplating the simultaneous heat transfer mechanisms of radiation and convection between the oven vault and floor surface areas. The efficacy of the semiempirical modeling developed here was further tested by reconstructing quite accurately the time course of water heating in aluminum trays with a diameter near to that of a typical Neapolitan pizza. The heat flow from the oven vault to the water-containing tray was of the radiative and convective types for about 73% and 15%, whereas the residual 12% was of the conductive type from the oven floor. PRACTICAL APPLICATION: Despite wood-fired ovens are largely used in the restaurant and food service industry, their operation is highly dependent on the operator's ability. This study shows how the heat loss rates through flue gas and insulated oven chamber can be assessed, and how the enthalpy accumulation rate in the internal fire brick oven chamber can be predicted by accounting for the simultaneous heat transfer mechanisms of radiation and convection between the oven vault and floor surface areas. The efficacy of this semi-empirical modelling was further checked for via some water heating tests.

Keywords: energy losses through flue gas and insulated oven chamber; energy supplied by wood combustion; material and energy balances; pseudo-steady-state regime performance; thermal efficiency; water heating test; wood-fired pizza oven.