Modeling Condensation and Evaporation on Fruit Surface

Abstract

Rewarming of fruits and vegetables after cooling is characterized by heat and mass transfer processes, which leads commonly to condensation of water on the produce surface at temperatures below the dew point. This effect may affect the produce quality due to microbial growth at unfavorable environmental conditions. The amount of condensed water is a function of the produce surface temperature and of the surrounding conditions as air temperature, air humidity, and air flow. Under practical conditions, both the warming and the condensation are strongly affected by the packaging system used. Depending on the flow conditions close to the produce surface, parameters of heat and mass transfer under laboratory conditions were measured. A mathematical model was developed for the determination of the amount of condensed water on fruit surfaces, its reevaporation, and its total dwell time dependent on the environment air conditions. The model describes the heat and mass transfer processes on single fruits. The process of diffusion of humidity in air and proceed of surface temperature is the basis for the model.

Keywords:

• Fruit drying
• Modeling mass transfer
• Surface drying
• Water evaporation

ACKNOWLEDGEMENTS

The authors gratefully acknowledge financial support of the German-Hungarian TÉT D-5/03 and BMVEL 7/04 foundation; Cs.M. also acknowledges support of the Bolyai Fellowship BO/00192/05-2005.