Surface Evaporation and the Boundary Layer

Water must move from the interior to the surface and then from the surface into air. Either step can limit the overall drying rate.

A thin zone of air at the product surface differs from the chamber bulk air. Its humidity and temperature depend on local evaporation and air movement.

Moderate movement can reduce resistance and support uniform transfer. Strong jets or continuous fan exposure can strip moisture from one face and intensify gradients.

Temperature and relative humidity determine the vapour-pressure difference driving evaporation. Condensation reverses the intended direction by wetting the surface.

Casing, rind, fat cover, shape and surface chemistry influence evaporation. Internal diffusion must supply water as the surface loses it.

Use restrained, mapped airflow appropriate to chamber scale, and judge the product for surface-to-core uniformity rather than treating maximum air speed as the goal.