ABSTRACT
Authors of a book such as this must answer a fair question. It is true that we already have scores of conventional dryers with well-established records of performance for drying most materials. However, not all of these drying technologies are necessarily optimal in terms of energy consumption, quality of dried product, safety in operation, ability to control the dryer in the event of process upsets, ability to perform optimally even with large changes in throughput, ease of control, and minimal environmental impact due to emissions or combustion of fossil fuels used to provide energy for drying. Most drying technologies were developed empirically over sustained periods of time, often by small vendors of drying equipment with little access to research and development (R&D) resourceshuman or fi nancial. They were also designed at a time when energy and environmental considerations as well as quality demands were not very stringent. Indeed, many have been upgraded satisfactorily to meet the legislative and competitive restrictions. Perhaps most are already designed and operated at their asymptotic limit of performance. However, if for any reason we wish to exceed their current performance in a cost-effective way, we need to look for alternative technologies with a higher asymptotic limit to performance, which is necessarily below the maximum defi ned by thermodynamic constraints.
