Low-order diffusive heat and mass transfer model for convective–radiative heating of a wet brick during energy investigation of an electric oven: Static mode

Abstract

Electric ovens typically belong to the low-efficiency category among electric appliances, exhibiting efficiencies typically ranging from 10% to 12%. To enhance efficiency, the home appliance industry focuses primarily on integrating advanced technologies. The energy efficiency index (EEI) for these appliances is in accordance with the testing standards specified in the EN 60350-1 standard. During testing, a standard wet brick inside the oven undergoes controlled heating from its initial temperature to a specified level, underscoring the need for precise modelling techniques. In this study, we propose a low-order dynamic model designed to predict the transient thermo-fluid behaviour of a domestic electric oven during energy consumption tests conducted in natural convective mode. This model accounts for simultaneous heat and mass transfer between the cavity air and the wet brick, employing a lumped model approach that optimizes computational efficiency. The oven is systematically divided into five subsystems: door, cavity, ventilation, cabinet, and wet brick, modelled using fundamental equations. Boundary conditions are calibrated using empirical correlations derived from experimental data, imparting a grey-box characterization to the system. Model parameters are meticulously tuned and calibrated based on available physical data. Following calibration, the model undergoes verification against additional experimental data to ensure its accuracy. The model effectively predicts transient variables such as cavity wall temperature, brick core temperature, and ventilation flows well within permissible error margins. Furthermore, it forecasts oven energy consumption, brick heating duration, and water evaporation, all within acceptable error limits of 15%. This comprehensive approach not only enhances our understanding of oven performance dynamics but also contributes to optimizing energy efficiency in domestic electric appliances.