ABSTRACT
Humidification and dehumidification are generic terms related to air and water vapour systems, but can be generalized as a gas–liquid system involving two-phase mass transfer operations. The magnitudes of the concentrations across the interface decide the process of either humidification or dehumidification to occur. Since, in humidification and dehumidification processes, only liquid migrates across the gas–liquid interface, all properties of gas–liquid mixture are dependent on the quantity of liquid vapour present per unit mass of vapour-free gas. Humidified and dehumidified air is used in various practical processes dealing with foods. Dehumidified air is used in various drying and dehydration, for the maintenance of free-flowing characteristics of hygroscopic materials, extension of storage life of processed foods, solvent recovery system, evaporative cooling of air. In industry, continuous dehumidification is carried out by rotary desiccant wheel. Liquid desiccant dehumidification system contains two separate chambers: one performs the dehumidification, and the other is in the process of reactivation.
