Heat Transfer Enhancement Techniques. With Special Attention to Passive Methods of Heat Transfer Enhancement

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Chapter 3.1 THEORY OF HEAT TRANSFER ENHANCEMENT TECHNIQUES:
Several heat transfer enhancement (HTE) techniques have been used in many engineering applications such as nuclear reactor, chemical reactor, chemical process, automotive cooling, refrigeration, and heat exchanger, etc. HTE techniques are powerful tools to increase heat transfer rate and thermal performance as well as to reduce of the size of heat transfer system in installing and operating costs. However, the need for miniaturization of thermal equipment has shifted the focus to the development of new high performance fluids with thermal conductivities higher than those of the conventional liquids. These high performance fluids can contribute to the evolution of space-saving yet cost effective thermal equipment with higher competitiveness in the global market.
Heat transfer enhancements can be achieved through active and passive methods as suggested by Ahuja [15] and Bergles [16]. Active heat transfer enhancement is achieved by the application of external energy on the fluid. Passive enhancement is attained by increasing the fluid surface area, providing artificially roughed surface, by turbulence promoter (such as special surface geometries, twisted tape, propeller, tangential inlet nozzle, snail entry, axial/radial guide vane, spiral fin) or fluid additives (such as nanofluid), of the passive methods, the heat transfer enhancement with nanofluid is highly encouraging. Due to ist easy installation/operation and cost saving, passive method has drawn great attention.
Generally speaking, tube flow can be divided into two parts [17] the boundary flow and the core flow. The boundary flow is a fluid region near the wall in the tube, beyond which in the tube the core flow is defined. Heat transfer enhanced tubes such as [18-21] spiral grooved tube, longitudinal troughed tube, corrugated tube, inner-finned tube, spiral-ribbed tube, micro-ribbed tube and so on, are mainly considered to

Prof. Md. Sadique Chakole is currently working as an Assistant Professor at G.H. Raisoni College of Engineering and Management, Ahmednagar, which is one of the best reputed institutes in India. He completed his master's degree with distinction and special awards from the institute. He completed his bachelor's degree with distinction in each semester and he has secured the first rank for a number of times. His project was awarded as best project in various national and international competitions. He has won more than ten prices at national events for his paper presentations.