Exergetic Performance Comparison between Steam-Heated and Closed-Cycle Heat Pump Applications for Lumber-Drying

Exergy analysis is a very strong method to evaluate the performance of energy-related systems from the thermodynamic point of view. Because, unlike the energy analysis, exergy analysis enables to determine the location and amount of the irreversibilities, which cause inefficiencies in the system and its components. In this study, the results of exergetic performances of two various heating systems, namely a steam- heated system and a closed-cycle heat pump system, for lumber- drying are considered and compared for the first time to the best of the authors' knowledge. The thermodynamic inefficiencies of the system components are evaluated in parts. The results show that the condenser in the closed-cycle heat pump is the most important system component for efficiency improvement. By comparison, various investigators reported in their similar studies that exergy efficiency values varied between 76-97%.