This paper is concerned with the withering of tea by the combined continuous belt system. It reports the energy and exergy analysis of the withering process in the less than ideal working environment of the Camli Tea Factory at Of, Trabzon, Turkey. Its focus is the investigation of withering phenomena in the trough. Using actual operating data, a mathematical model of the withering unit with irreversibilities is derived, allowing thermodynamic assessments to be made with the ultimate purpose of determining the effects of atmospheric conditions on optimising net energy input to the system and production rate. The ideal working environment for the Camli Tea Factory and second-law efficiency are obtained using graphical visualisation as well as numerical calculations. The method is well suited for analysing the thermodynamic model and identifying exergy losses in the withering process. The results provide valuable information regarding the withering process and will be useful for designers and operators of withering units.