In contact dryers, the product is brought into contact with a hot surface. The solvent is evaporated by the transfer of heat from wall to product. It is the most suitable drying process for difficult–to–handle pastes, sludge or liquids. It is also highly recommended for drying in inert atmospheres, and for solvents recovery.
The low flow of solvent-saturated exhaust vapor and the high energetical efficiency are two of the main advantages of contact drying. These dryers require a relatively high initial investment, since they are generally more complex to manufacture.