Second law applications in modeling, design and optimization

David Michael Paulus, Marquette University

Abstract

The dissertation applies the Second Law of Thermodynamics to a variety of problems, with the ultimate goals of both improving the design process and the methods by which new technologies might be conceived and developed. It is divided into three parts, attacking basic thermal science, modeling and finally, design. The first two parts discuss topics that are ultimately relative in the third. One can think of each three as a layer; basic science forms the foundation of what we do as engineers. Modeling is how we apply this science to real problems. Design (and/or analysis) moves the exercise from the mathematical to the physical (and useful). The first article in the dissertation investigates entropy extremization in a variety of physical processes. It is noted that at (most) times this extremization is maximization, but at times a minimization occurs. The second article shows how a common performance measure, entropy production, can be used to replace a variety of equipment "efficiency" definitions. Then, it is extended to replace kinetic relations for fluid flow and heat transfer processes. In all cases it is developed in a non-dimensional form. The work in the third article originated with an Air Force Office of Research Support proposal for the optimization of aircraft energy conversion subsystems. The optimization of these subsystems proves to be more intricate than many traditional energy system design problems, as figures of merit for the vehicle as a whole are difficult to translate into values that will be meaningful to an on-board energy system (or subsystem or device). In this section, a methodology is given for writing an overall objective function. It is then shown how this overall function, through thermoeconomics, may be applied to detailed design of energy conversion systems, subsystems and devices. In addition, notes are made as to the proper method of "dead state" and exergy costing methodology; these areas are important to the proper application of thermoeconomics. The third article concludes with real case studies as applied to a light aircraft.

Recommended Citation

Paulus, David Michael, "Second law applications in modeling, design and optimization" (2000). Dissertations (1962 - 2010) Access via Proquest Digital Dissertations. AAI9991616.
https://epublications.marquette.edu/dissertations/AAI9991616

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