Prediction of Wet-Bulb Globe Temperatures in Aluminum Smelters

The wet-bulb globe temperature (WBGT) is the heat stress index commonly used to evaluated heat exposure in the work-place. Presently, the heat exposure in aluminum smelters can only be measured after the start-up of the process, because no reliable method exists for its prediction during the design stage. In this study, a method is outlined that can predict the WBGT in cell rooms of aluminum smelters. The method is based on a fundamental approach using a radiation analysis of a prebake cell room and a heat transfer analysis of the WBGT instruments. The method was validated against plant measurements over a wide range of WBGT values. The difference between observed and predicted values of the area WBGT was less than 3%. Thus, heat exposure may be evaluated during the design stage of a smelter and appropriate steps may be taken to improve the design, if necessary.