This study investigates heat and moisture transfer between a sweating film and a nonwoven sheet both experimentally and numerically. A mathematical model based on heat conduction and moisture diffusion in both the air gap and cloth is presented. The evaporation rate and surface temperature of the sweating film are well predicted under various conditions such as air gap height, heating conditions, and sweating film orientation by evaluating the effective thermal conductivity and diffusion coefficient from the empirical equations of the Nusselt number for a fluid layer, even though the air gap height is sufficiently large to cause natural convections. List of symbolsc p Heat capacity (J/kg K) c w Moisture concentration (kg/m 3 ) D m Diffusion coefficient (m 2 /s) f e Shape factor Gr Grashof number g Gravity acceleration (m/s 2 ) h m Mass transfer coefficient (m/s) h t Heat transfer coefficient (W/m 2 K) L Height of permeable film (m) L vapor Latent heat of vaporization (J/kg) m conv Convective mass flux of moisture vapor (kg/m 2 s) m vapor Mass flux of moisture vapor (kg/m 2 s) Nu Nusselt number Pr Prandtl number q Heat flux (W/m 2 ) Sc Schmidt number s Height of fluid layer (m) T Temperature (K) t Time (s) y Coordinate (m) Greek symbols a Porosity b Coefficient of volume thermal expansion (1/K) d Air gap height (m) e Emissivity k Thermal conductivity (W/mK) l Viscosity (Pa s) q Density (kg/m 3 ) r Stefan-Boltzmann constant (W/m 2 K 4 )

In this study ， a mathematical model of heat transfer and Huid flow in air gap between hot surface and air − permeabte sheet wit ］ 1 periodic oscillation is developed ． In the modeL an arbitrary Lagrangian − Eulerian Finite element method is used to simulate the perlodic oscillation of the sheet such as stroke distance． The effect ofperiodic motion ofthe sheet on thc heat transfer and tluid ∩ow in the air gap is discusscd ． From the results ， the osclllation ofair permeable sheet enhances the Nusselt numbcr on the hot surface ， In addition ， an increase in the stroke distance ofthe osci 珪ation inlproves the heat transfer charac し eristics ． Key Mords ；Convective heat transfer in air gap， Periodic ⊂ )sci ［ ［ ation ofair − permeable sheet ， Numerical simu ［ ation