EXPERIMENTAL-STUDY OF SIMULTANEOUS HEAT AND MOISTURE TRANSFER AROUND SINGLE SHORT POROUS CYLINDERS DURING CONVECTION DRYING BY A PSYCHROMETRY METHOD

This paper presents results of theoretical and experimental studies on heat and moisture transfer around single short porous cylinders durin g forced convective drying. Air was passed across saturated coal logs, varying air humidity, temperature and velocity, as well as log aspect ratio and diameter. After considering the transport coupling effects, experimental results from loss of moisture and surface temperature in dicate that calculated heat transfer coefficients are twice coefficien ts for systems with only heat transfer. The coupled heat and mass tran sfer results are correlated in terms of the dimensionless Nusselt and Sherwood numbers, Nu = 0.056 Re-0.65 Gu(-0.43) and Sh = 0.047 Re-0.67 Gu(-0.42), where Re is the Reynolds number and Gu the Gukhman number. The surface temperatures during drying were well estimated using a mod ified energy balance formula. The new correlation is useful to predict the initial drying rates for short cylinders with an aspect ratio fro m 1.2 to 2.0. Copyright (C) 1996 Elsevier Science Ltd.