A Discussion on a Generalized Correlation for Drying Rate Modeling

Abstract

In this article, a model generalized for drying prediction in literature has been examined critically using an analogy between heating or cooling of a solid object and drying. It can be shown that the generalized model is more appropriate to be considered as an empirical fit as it does not seem to yield the liquid water diffusivity in the correct range as reported in previous laboratory studies. The model equation can be seen to be more suitable for describing the second period of drying, which is after an induction time period that may cover the warming up or cooling down start-up period and sometimes the constant rate period when the rate is considered to be based on unit surface area. On the other hand, it is interesting to observe in the current analysis that it is possible to deduce the order of magnitude of the effective liquid water diffusivity from an appropriately formulated penetration time model.

Keywords:

• Drying model
• Heating and cooling
• Mass transfer coefficient
• Moisture diffusivity