A simple model and validating experiments for predicting the heat transfer to a load situated in an electrically heated oven Original Research Article

A fully predictive, algebraic method has been developed for the prediction of the timewise temperature variation of a thermal load situated in an electrically heated oven. The model which underlies the method takes into account both natural convection within the oven cavity and radiation between the thermal load and the oven walls. The model provides a complete description of heat transfer external to the thermal load. It can be used to provide boundary conditions for an analysis of thermal loads of various heat-conducting characteristics. This method is able to accommodate loads of various shapes, sizes, materials, and radiation surface finishes, as well as oven heating conditions characterized by a wide range of oven set-point temperatures. Extensive experiments were performed to validate the predictive method. These experiments encompassed thermal loads of different shapes, masses, and surface finishes. Measurements were made of the transient response of the thermal load. The results of these experiments reveal overall agreement to within about 1% between the predictions and the data, thereby validating the veracity of the assumptions that underlie the predictive model. Encompassing temperature data were collected at 170 sites on the oven walls. These data have been brought together in the form of isotherms. Among the walls, the temperatures on the oven door were the lowest, whereas the highest temperatures were encountered on the oven floor and on the top wall. Thermal symmetry was found to prevail on most of the walls, with the greatest deviations from symmetry in evidence on the sidewalls.