Introduction to Enhanced Heat Transfer

The fundamentals of heat transfer enhancement in heat-exchanging devices have been introduced in this chapter. The classification of heat transfer technology and different heat transfer techniques has been presented. The need for augmentation and its benefits have also been discussed.

A detailed discussion on the active, passive and compound techniques has been presented in this chapter. A good number of works on single-phase and two-phase heat transfer augmentation techniques, carried out by researchers across the globe, have been reported. The commercial applications of various techniques such as ribs, corrugated tubes, three-dimensional roughness, electrohydrodynamic forces, surface vibrations, pin-fin arrays, jet impingement and bubble injection have also been discussed.

In this chapter, heat exchanger design theory has been discussed. The heat transfer coefficient and friction factor for laminar flow and turbulent flow through ducts, tube banks, thin-film condensation and nucleate boiling have been presented. Also, the concept of fin efficiency and Reynolds analogy has been explained.

Fouling on various types of enhanced heat transfer surfaces has been discussed in this chapter. Fouling fundamentals in respect of liquids and gas flow have been considered in detail. Liquid fouling in internally finned tubes, rough tubes, plate-fin geometry and fouling in plate heat exchanger is an important consideration. Modelling of fouling in enhanced tubes and correlations for fouling in rough tubes have been dealt with adequately.

In this book, introduction to enhanced heat transfer has been discussed in detail. Both passive and active techniques along with their commercial applications have been dealt with. Fundamentals of heat transfer and necessary correction for variation of fluid properties are to be understood clearly to appreciate the impact of heat transfer enhancement on the improved design of compact heat exchangers. This has been followed by complete treatment of fouling on enhanced surface. Fouling fundamentals, fouling of gases on finned surfaces, shell-side fouling of liquids, liquid fouling in internally finned tubes, rough tubes and plate-fin geometry and fouling in plate heat exchanger have been discussed at length. This book ends with the complete treatment of correlations and modelling of fouling in enhanced tubes.