In the present study the phenomenon of drying a wet substance under vacuum has been investigated numerically. At first, the environment air pressure of the sample was reduced linearly in 1 min and then became constant. In this study the effect of heat and mass transfer coefficients on the temperature and moisture rate has been considered and the temperature and moisture rate distributions in the square -shaped substance due to the reduction of vacuum chamber pressure are predicted by numerical method. It is shown that for a high heat transfer coefficient, the center temperature of the apple gets to the balanced temperature rapidly, because much more heat is transferred from the fluid to the surface, while in similar conditions, no significant change in the moisture rate is observed. While changing the mass transfer coefficient has no effect on the temperature distribution, but the sample moisture rate is changed under the same conditions.

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