Entropy Generation for Free and Forced Convection in a Porous Cavity and a Porous Channel

Abstract

The concept of irreversibility is based on the second law of thermodynamics which serves to optimise the design of thermal, fluid and energy systems. The theories of reversibility and irreversibility are important in thermodynamics and crucial to the exergy method. Understanding the nature of irreversibility and how to minimise them in practice is essential for an engineering thermodynamicist. Contemporary engineering thermodynamics uses the rate of entropy generation as a parameter to quantify the significance of these irreversibilities. The local values of entropy generation due to viscous and thermal effects can be mapped to detect, by inspection, the key areas that requires a design modification. This emerging technology is viewed to have a meaningful potential for improving thermal systems design. In the thermal design decisions the utilisation of the second law of thermodynamics is very well referenced, see Bejan [5, 7]. Drost and White [8] studied numerical calculations of local entropy generation maps in an impinging jet whilst San et al. [15] studied entropy generation in convective heat and mass transfer within a smooth channel under some specific thermal boundary conditions. Baytas [2, 3] studied the optimisation in an inclined enclosure for minimum entropy generation in natural convection and Baytas and Pop [4] investigated the thermodynamic analysis of flow and heat transfer inside a trapezoidal cavity filled with a porous medium. Nag and Mukherjee [13]] studied thermodynamic optimisation of connective heat transfer through a duct with constant wall temperature