ID 1138891 1 American Institute of Aeronautics and Astronautics Implementation of a Non-Equilibrium Exergy Analysis for an Aircraft Thermal Management System Rory A. Roberts 1 Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH, 45435 John H. Doty 2 Engineering Management & Systems, The University of Dayton, Dayton, OH, 45469 System optimization and design of an aircraft is required to achieve multiple objectives. Often one of the main objectives is system efficiency for reduction in fuel use for a given mission. System efficiency can be quantified by either a 1st or 2nd law thermodynamic analysis. A 2nd law exergy analysis can provide a more robust means of accounting for all of the energy flows within and in between subsystems. These energy flows may be thermal, chemical, electrical, pneumatic, etc. The incorporation of a transient system analysis in the design process of an aircraft can provide untapped opportunities for gains in energy efficiency of the aircraft's operation. In order to quantify the efficiency gains utilizing a 2nd law exergy analysis, the non-equilibrium term of exergy generation must be accounted for in the analysis. This paper demonstrates the implementation of a non-equilibrium exergy analysis of a heat exchanger. Nomenclature S = entropy, [kJ/K] i S & = entropy rate (i=in,out,gen,) [kW/K] m & = mass flow rate, [kg/s] C p = specific heat, [kJ/kg/K] P = pressure, [kPa] V = control volume, [m 3 ] dt = time step i E & = energy rate (i=in, out), [kW] ρ = density of the air, [kg/m 3 ] T = temperature, [K] h = convective heat transfer coefficient, [kW/m 2 ] i q = heat flux, [kW] R = ideal gas constant, [kJ/kg/K] I. Introduction ONCEPTUAL design groups have traditionally designed aircraft from a subsystem-level viewpoint. Consequently, subsystems such as the propulsion, electrical and thermal management systems are often optimized without consideration of vehicle-level interaction. This could result in a final aircraft design that is not truly optimized. It is proposed that vehicle-level analysis of subsystem interactions could result in significant performance gains across the aircraft, potentially improving the overall effectiveness of future platforms 1-3 . 1 Assistant Professor, Wright State University, Dept. of Mechanical and Materials Engineering, AIAA Member 2 AFRL Researcher, University of Dayton, Department of Engineering Mgt. & Systems, AIAA Senior Member Copyright clause. C 50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 09 - 12 January 2012, Nashville, Tennessee AIAA 2012-1126 Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Downloaded by John Doty on November 30, 2015 | http://arc.aiaa.org | DOI: 10.2514/6.2012-1126