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Abstract
Convective drying of rectangular-shaped moist object has been analyzed both experimentally and numerically. Transient mass of the potato sample is measured experimentally. Moisture content, diffusivity, and density of the object are calculated at different drying air temperatures from 40°C to 70°C with an air velocity of 2 m/s. A three-dimensional (3D) finite volume method (FVM) based numerical model is developed to predict the temperature and moisture distribution. A computational fluid dynamics (CFD) code is used for predicting heat and mass transfer coefficients required in the boundary conditions of the heat and mass transfer model. The experimental and numerical data are compared and good agreement is observed.
ACKNOWLEDGMENT
The author acknowledges with thanks the support received by way of proof reading from Dr. M. R. Vishwanathan, Assistant Professor of English, Humanities and Social Science Department, NIT Warangal, India.
NOMENCLATURE
| B | = | breadth of the rectangular potato sample [m] |
| db | = | dry basis |
| dL | = | change in length [%] |
| dB | = | change in breadth [%] |
| dH | = | change in width [%] |
| D | = | moisture diffusivity [m2/s] |
| DAB | = | moisture diffusivity of gas phase [m2/s] |
| D0 | = | preexponential factor [m2/s] |
| h | = | heat transfer coefficient [W/(m2K)] |
| H | = | width of the rectangular potato sample [m] |
| hm | = | mass transfer coefficient [m/s] |
| k | = | thermal conductivity [W/(mK)] |
| L | = | length of the rectangular potato sample[m] |
| Le | = | Lewis number |
| M | = | moisture content [kg/kg of db] |
| p | = | pressure [N/m2] |
| T | = | temperature [°C] |
| t | = | time [s] |
| u,v,w | = | velocities in X, Y, and Z direction [m/s] |
| X,Y,Z | = | coordinate axes/directions |
Greek symbols
| α | = | thermal diffusivity [m2/s] |
| ρ | = | density [kg/m3] |
| μ | = | viscosity [kg/(m.s)] |
| Φ | = | nondimensional moisture content |
Subscripts
| a | = | air |
| c | = | characteristic |
| eq | = | equilibrium |
| eff | = | effective |
| w | = | surface |
| m | = | mass, mean |
| n | = | normal to surface |
| s | = | coordinate along the surface |
| 0 | = | initial condition |
| ∞ | = | supplied air condition |