Entropy production for cylinder drying of linerboard and newsprint

Abstract

For industrial paper drying, the entropy production from heat and mass transfer irreversibilities was determined by combining principles of irreversible thermodynamics with information from a dryer simulator. Transport irreversibilities depend on sheet and dryer characteristics. Entropy production for multi-cylinder paper dryer sections was compared for 5 paper machines, producing 3 grades of linerboard, 2 of newsprint. The three major contributions to entropy production were evaluated: entropy production for evaporation of water, for convective heat transfer between the sheet and ambient air, and for cylinder-to-sheet heat conduction. Effects on entropy production from paper basis weight and drying cylinder steam pressure were examined.