Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.
Thermal dehydration processes are highly energy-intensive
and are found in almost all industrial sectors, accounting for 10
to 20 percent on national industrial energy consumption in
developed countries. With escalating energy costs and need to
mitigate environmental pollution due to emissions from
combustion of fossil fuels, it is increasingly important to
develop innovative drying technologies. Furthermore, drying
also affects quality of the dried product due to physical and/or
chemical transformations that may occur during the heat and
mass transfer operation. With tens of thousands of products that
are dried in hundreds of dryer types, it is a formidable task
indeed to develop design and scale-up procedures of wide
applicability. Attempts have been made over the past three
decades to make fundamental and applied contributions to
transport phenomena and material science aspects in drying of
various forms of wet solids, pastes and liquids. This
presentation will attempt to summarize the state-of-the-art as
far as theoretical understanding of drying processes and provide
examples of some new technologies being developed.
Opportunities for challenging fundamental and modeling
studies to enhance drying technologies will be identified.
Illustrative results will be presented to show how mathematical
modeling of spray, spouted bed and heat pump dryers can be
utilized to develop new conceptual designs and to optimize
operating conditions as a cost-effective route to intensify
innovation in thermal dryer design.