Fundamental Characteristics of Combined Impingement and Through Air Drying of Paper

An experimental facility was developed to determine fundamental characteristics of combined impingement and through air drying of paper. Removal of impingement boundary layer humidity by through flow makes both components of the combined process nonadiabatic, complicating the analysis. Water removal rate curves for both the impingement exhaust and the through flow exhaust are strikingly different from pure impingement and pure through drying rate curves, with the through flow water removal rate curve having at times a unique, secondary increasing rate period. Total drying rate is enhanced substantially by removal of a small fraction of the drying air as through flow exhaust.