Diffuser and Nozzle Design Optimization by Entropy Generation Minimization

Abstract: Diffusers and nozzles within a flow system are optimized with respect to theirwall shapes for a given change in cross sections. The optimization target is a low value ofthe head loss coefficient K, which can be linked to the overall entropy generation due to theconduit component. First, a polynomial shape of the wall with two degrees of freedom isassumed. As a second approach six equally spaced diameters in a diffuser are determinedby a genetic algorithm such that the entropy generation and thus the head loss is minimized.It turns out that a visualization of cross section averaged entropy generation rates along theflowpathshouldbeusedtoidentifysourcesofhighentropygenerationbeforeandduringtheoptimization. Thusit willbe possibleto decide whether a givenparametric representation ofa component’s shape only leads to a redistribution of losses or (in the most-favored case) tominimal values for K. Keywords: second law analysis; entropy generation; optimization;diffuser 1. Introduction

[1]  Peter Atkins.  The Second Law , 1984 .

[2]  Jung-Yang San,et al.  Second-law analysis of a wet crossflow heat exchanger , 2000 .

[3]  Zhen-Xiang Gong,et al.  Entropy Generation Minimization , 1996 .

[4]  Mohammad Hassan Saidi,et al.  Exergy model of a vortex tube system with experimental results , 1999 .

[5]  Adrian Bejan,et al.  Thermodynamic optimization of geometric structure in the counterflow heat exchanger for an environmental control system , 2001 .

[6]  K. Ting,et al.  Entropy generation and optimal analysis for laminar forced convection in curved rectangular ducts : A numerical study , 2006 .

[7]  Richard A. Gaggioli,et al.  Second law analysis for process and energy engineering , 1983 .

[8]  J. S. Dugdale,et al.  Entropy And Its Physical Meaning , 1996 .

[9]  Raphael T. Haftka,et al.  Response Surface Techniques for Diffuser Shape Optimization , 2000 .

[10]  H. Herwig,et al.  Direct and indirect methods of calculating entropy generation rates in turbulent convective heat transfer problems , 2006 .

[11]  A. Bejan.  The Concept of Irreversibility in Heat Exchanger Design: Counterflow Heat Exchangers for Gas-to-Gas Applications , 1977 .

[12]  DUSáAN P. SEKULICá.  Entropy Generation in a Heat Exchanger , 1986 .

[13]  Heinz Herwig,et al.  Internal Flow Losses: A Fresh Look at Old Concepts , 2011 .

[14]  F. Menter.  Improved two-equation k-omega turbulence models for aerodynamic flows , 1992 .

[15]  G. Janiga,et al.  Optimization and Computational Fluid Dynamics , 2008 .

[16]  J. E. Hesselgreaves.  Rationalisation of second law analysis of heat exchangers , 2000 .

[17]  H. Herwig,et al.  Local entropy production in turbulent shear flows: a high-Reynolds number model with wall functions , 2004 .

[18]  D. K. Anand,et al.  Second Law Analysis of Solar Powered Absorption Cooling Cycles and Systems , 1984 .

[19]  A. Bejan,et al.  Entropy Generation Through Heat and Fluid Flow , 1983 .

[20]  Heinz Herwig,et al.  The Role of Entropy Generation in Momentum and Heat Transfer , 2012 .

[21]  A. Bejan.  A Study of Entropy Generation in Fundamental Convective Heat Transfer , 1979 .

[22]  Mamdouh El Haj Assad,et al.  Thermodynamic analysis of an irreversible MHD power plant , 2000 .

[23]  H. Göhr,et al.  G. Falk und W. Ruppel: Energie und Entropie, eine Einführung in die Thermodynamik. Springer-Verlag, Berlin, Heidelberg, New York 1976. XIV, 411 Seiten, 189 Abbildungen, Preis: DM 58,—. , 1977 .

[24]  R. Y. Nuwayhid,et al.  On entropy generation in thermoelectric devices , 2000 .

[25]  Dilip Kumar Pratihar,et al.  An evolutionary optimization of diffuser shapes based on CFD simulations , 2009 .

[26]  Elliott H. Lieb,et al.  A Fresh Look at Entropy and the Second Law of Thermodynamics , 2000 .