Special Topics in Heat Transfer

A number of specialized subjects in heat transfer are important in modern technology. In this chapter we shall present a brief introduction to five such topics. The treatment here is not intended to be comprehensive, but rather to indicate the basic physical mechanism of the processes involved. It would be possible, of course, to include these topics in other chapters of the book, but we choose to group them together in order to focus more specialized attention on the subject matter. Since the discussions which follow represent only cursory treatments of the subjects, the serious reader will wish to consult the appropriate references for additional information. 

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M9. Metzner, A. B., Lecture Notes in Chemical Engineering 564 (Special Topics in Heat Transfer), University of Delaware, Newark, 1953. 

Topics that acquire special importance on the industrial scale are the quality of mixing in tanks and the residence time distribution in vessels where plug flow may be the goal. The information about agitation in tanks described for gas/liquid and slurry reactions is largely apphcable here. The relation between heat transfer and agitation also is discussed elsewhere in this Handbook. Residence time distribution is covered at length under Reactor Efficiency. A special case is that of laminar and related flow distributions characteristic of non-Newtonian fluids, which often occiu s in polymerization reactors. 

Convective heat transfer has become a subject of very wide extent and the selection of material for inclusion in a book of the present type requires careful consideration. In this book, heat transfer during boiling and solidification have not been considered. This is not in any way meant to suggest that these topics are of lesser importance than those included in the book. Rather, it is felt that the student needs a good grounding in the topics covered in the present book before approaching the analysis of heat transfer with boiling and solidification. The book thus lays the foundation for more advanced courses on specialized aspects of convective heat transfer. 

Recent inventions in micro and nano-scale systems and the development of micro and nano-scale devices continues to pose new challenges, and the understanding of the fluid flow and heat transfer at such scales is becoming more and more important. In Chapter 6, microscale heat transfer is presented as a Topic of Special Interest. 

Most chapters contain a real world application, end-of-chapler optional section called Topic of Special Interest where interesting applications of heat transfer are discussed such as Thermal Comfort in Chapter 1, A Brief Review of Differential Equations in Chapter 2, Heat Transfer through the Walls and Roofs in Chapter 3, and Heat Transfer through Windows in Chapter 9. 

The topic of transport effects in catalysis is revisited in Chapter 9. The structure of porous catalysts is discussed, and the internal and external resistances to heat and mass transfer are quantified. Special attention is devoted to helping the student understand the influence of transport effects on overall reaction behavior, including reaction selectivity. Experimental and computational methods for predicting the presence or absence of transport effects are discussed in some detail. The chapter contains examples of reactor sizing and analysis in the presence of transport effects. 

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