Energy and Exergy Analysis of Paper Drying Process in Convective Type Dryer H. Basirat Tabrizi 1 , Z. Mansoori 2 and B. A. Monfared 1 1 Amirkabir University of Technology, Mech. Eng. Dept., P.O. Box 15875-4413, Tehran, Iran email: hbasirat@aut.ac.ir http://www.aut.ac.ir 2 Amirkabir University of Technology, Energy Research Center, Tehran, Iran Abstract This research is concerned with the energy and exergy analysis of drying process of paper. Analyses are mostly concentrated on efficiency variations caused by alteration of temperature and velocity of drying air. Drying experiments were conducted at inlet temperatures of 90°C and 150°C, and at drying air velocities of 1.4m/s and 0.5m/s in the convective type chamber dryer in a tray. Energy analysis using first law of thermodynamics demonstrates energy efficiency. Exergy analysis, also, is employed to determine exergy efficiency and exergy loss. It was observed that the inlet air temperature has an integral effect on exergy loss and exergetic efficiency, whereas drying air velocity affects energetic efficiency. Keywords: energy, exergy, efficiency, Drying Paper, experiment 1 Introduction Drying is one of the most important stages in production of solid materials as of paper sheets. The term drying generally refers to the process in which the moisture is removed from a wet solid in gaseous phase by heating the solid or any other procedures resulting in increase of partial pressure of moisture. Actually, the objective of a dryer is to supply the product with more heat than is available under ambient condition. The required heat for the drying process is provided by drying air heated by solar and/or electricity energy. The heat supplied is transported by convection from the surroundings to the solid particle surfaces and, from there, by conduction, further into the particle throughout the drying process. In addition, moisture is removed in the opposite direction as a liquid or vapor. On the surface, it evaporates and passes on by convection to the surrounding. Many drying processes involve vaporization of water as moisture and air as drying medium. Recently, many studies have been undertaken by several researchers to investigate thermodynamic aspects of drying systems. Kavak Akpinar et al. [1] developed the thermodynamic analyses of single layer drying process of pumpkin slices via cyclone type dryer. In addition, Kavak Akpinar et al. [2] repeated their study in which drying process of the single layer potato slices via a cyclone type dryer was undertaken. Using the first law of thermodynamics, energy analysis was performed to estimate the ratios of energy utilization. However, exergy analysis was accomplished to determine the location, type, and magnitude of exergy losses during drying process by applying the second law of thermodynamics. It was concluded that the exergy losses rose with the increase of the energy utilization in both trays and drying chamber. The most exergy losses took place during the drying of pumpkin slices on the first tray. In addition, Kavak Akpinar [3] investigated the energy and exergy analyses of the drying process of thin layer of red pepper slices. It was observed that the energy utilization ratio values decreases and the exergetic efficiency values increases with the increased drying time. Additionally, it was seen that the energy utilization ratio and the exergetic efficiency values in the drying chamber were almost equal at all the drying air temperature examined because the energy utilization, the useful energy, the exergy inflow, the exergy outflow, and the exergy losses increased with the increase of drying air temperature. Holmberg and Ahtila [4] evaluated the energy efficiency of bio-fuel drying in a pulp and paper mill based on energy and exergy analysis. The evaluation was based on the determination of the heat consumption and the irreversibility rate for energy and exergy analysis, respectively. The evaluation methods were applied to two different drying systems, single-stage-drying with partial recycle of spent air, and multi-stage-drying. Both drying systems were provided with a heat recovery unit in which the inlet air is pre-heated using the outlet air of the dryer. There were two alternative heat sources available for the drying energy, steam at a pressure of 3 bar