Convential exergy aspect of heat transfer and fluid flow through spiral passage subjected to consant wall temperature

Abstract

Exergy destruction of heat transfer and turbulent convective fluid flow through spiral passage subjected to constant wall temperature is analyzed. Constant and temperature dependent thermo physical properties models of process fluid have been adopted. Heat transfer characteristics and both thermal as well viscous fluid friction exergy destruction are investigated. The local variation of total (thermal and viscous dissipation) exergy destruction was studied along the spiral passage. Some of second law of thermodynamic dimensionless parameters, such as Bejan (Be) and entropy generation (Ngen) numbers were considered. It is found that De (Dean Number) with its magnitude is a measure of the secondary flow, and has opposite influence on these two numbers along the passage. The study concluded that total exergy destruction was dominated by thermal effects due to temperature difference. But the influence of irreversibility due to pressure drop was found less significant. This effect is of a particular interest in the heat transfer and fluid flow in spiral passages where secondary flow phenomenon plays an important role in thermal mixing and conversion of viscous dissipation into thermal energy through narrowing passage.