Heat transfer to newtonian and non newtonian fluids flowing across tube banks

Abstract

Heat is a form of energy and heat transfer is a thermal phenomenon from one region to another region as a result of temperature difference between them. In many cases, involving either a liquid or a gas, convection is an important and prime mode of heat transfer. Fluids used in transport operations in convection may have either a simple Newtonian flow characteristics or may be a more complex non-Newtonian fluid. newlineThe power generation field, the chemical industry, and other technology based industries increasingly employ heat exchangers involving tubes in cross-flow. The cross-flow over the bank of tubes represents the true picture of the flow encountered in the shell of heat exchangers. Most of the fluids encountered in chemical and allied processing applications do not adhere to the classical Newtonian postulate and are accordingly known as non-Newtonian. Frequent occurrence of such fluids in industries has created considerable interest in the study of bahaviour of these fluids in various process equipments where these are subjected to heating and /or cooling in heat exchangers. Therefore, the need of an appropriate model describing the real flow situation within the heat exchanger cannot be overlooked. newlineIt is appropriate to mention here that a bulk of the literature relates to the prediction of pressure drop, and only limited theoretical work has been reported on heat transfer even with Newtonian fluids. It is really surprising that despite such a widespread occurrence of non-Newtonian behaviour, the subject of convective heat transfer from non-Newtonian media flowing past bank of tubes have not been dealt adequately in most of the currently available literature. It thus seems desirable to undertake such a study with a view to explore these interesting details and to obtain the data for realistic situation. newline