Dynamic model for convective heating of a wet brick during energy characterisation of domestic electric ovens

Abstract

Electric ovens usually represent a low-efficiency category among household appliances, influencing the overall environmental impact of buildings. The energy class of such devices is determined through a test procedure defined by the EN 60350 European standard, where a wet clay brick is heated under set conditions and accurate control of the air temperature during the test is required, which marks the importance of efficient control strategies. In this work a control-oriented dynamic model was devised to predict the transient thermal behaviour of the oven during energy consumption tests carried out in forced-convective mode, including the heat and mass transfer occurring between the wet brick and the cavity air. Model parameters were determined through an optimisation procedure based on experimental data. Comparisons with other sets of experimental data also allowed to validate the predictive capability of the model. The model predicts well the temperature of the cavity air, the Pt500 probe used as a temperature feedback and the core temperature of the brick with deviations lower than 10% after the heating phase of the cavity. The brick heating time and water loss are also captured by the model, with deviations lower than 6% for the former and 9% for the latter.