| Abstract: | Liquid foods are often partially dehydrated to reduce their water content so as to enhance their storage stability. Evaporation, which consumes large amounts of energy, is the most widely used operation for concentrating liquid foods. The paper describes a novel system to concentrate liquid foods by using liquid desiccants. In the proposed system, water vapour, evaporated from the liquid food at reduced pressure, passes to the liquid desiccant, where it is absorbed while liberating its latent heat. The liquid desiccant temperature thereby increases. The warm liquid desiccant can then be used to provide a portion of the thermal energy for the evaporation of the water in the liquid food. A vertical, double-falling-film evaporator which uses calcium chloride solution was built and was used to concentrate liquid foods. The experimental set-up was tested to study the influence of the liquid-desiccant flow rate, the liquid-food flow rate, and the liquid-desiccant concentration and temperature. Some of the experimental results are discussed in this paper. |
