MODELING OF REFRACTANCE WINDOW FILM DRYER FOR LIQUIDS

Abstract

The aim of the present study is to develop mathematical analysis of a film dryer or refractance type dryer that helps in design, operation, modification, evaluating drying time and rates, improving quality and increasing energy efficiency. Strawberries juice was used as an example of liquid foods. For justifying this purpose a pilot plant refractance window dryer was designed. A film of juice with an initial thickness of approximately 3 mm, was applied on a hot glass plate heated by water underneath, that continuously contacts it. Nine experiments were conducted, namely: three variable flow rates per unit surface area of the dryer, 0.25, 0.21 and 0.18 m 3 /m 2 .s , and also three different levels of heating rates for each flow rate were also applied, i.e. 15.2 , 24.3 and 36.6kW/m 2 respectively. Liquid strawberries drying time ranged between