INVESTIGATION OF CONVECTION-RADIATION COMBINED HEAT TRANSFER MECHANISMS AT STEADY REGIME UNDER DIFFERENT OPERATIONAL AND PHYSICAL CONDITION SCENARIOS FOR OVEN

Abstract This study numerically investigates the effect of heater geometry, distance between heater and tray, and heater power on temperature uniformity of tray surface inside a food oven with natural convection and thermal radiation. To determine the effects of specified factors, a simulation study was conducted using the CFD method in a three-dimensional, steady-state regime with three levels and a full factorial analysis. Prior to this, a validation and verification study was conducted based on an experimental study from the literature on natural convection and radiation effects in a closed volume. As a result, the S2S radiation model, RNG k-ε turbulence, and enhanced wall treatment approach were found to be successful approaches. Results show that the temperature uniformity of the tray surface is predominantly determined by changes in heater geometry and distance between the heater and the tray. Changes in these two factors affect natural convection heat flow on the surface, controlling the presence of hot and cold regions on the surface. In addition, it was observed that heating power had no effect on temperature distribution on the tray surface within the specified range, but only changed average temperature values. The uniformity index and area ratio approach proposed in this study were used to determine temperature uniformity on the tray surface. Both methods yielded similar results. These findings provide a clear physical explanation of how radiation and natural convection jointly determine thermal uniformity and establish a quantitative basis for improving heater configurations.