1、Aircraft Thermal Management: Integrated Energy Systems AnalysisOther SAE books of interest: Aircraft Thermal Management: Systems Architectures By Mark F. Ahlers (Product Code: PT-177) Icing Acretion and Icing Technologies By Robert J. Flemming (Product Code: PT-163) Integrated Vehicle Health Managem
2、ent: Essential Reading By Ian K. Jennions (Product Code: PT-162) For more information or to order a book, contact: SAE INTERNATIONAL 400 Commonwealth Drive Warrendale, PA 15096 Phone: +1.877.606.7323 (U.S. and Canada only) or +1.724.776.4970 (outside U.S. and Canada) Fax: +1.724.776.0790 Email: Cust
3、omerServicesae.org Website: books.sae.orgAircraft Thermal Management: Integrated Energy Systems Analysis By Mark F. Ahlers Warrendale, Pennsylvania, USA Copyright 2016 SAE International eISBN: 978-0-7680-8304-0Copyright 2016 SAE International. All rights reserved. No part of this publication may be
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5、g; phone: 724-772-4028; fax: 724-772- 9765. Printed in the United States of America Library of Congress Catalog Number 2016930157 SAE Order Number PT-178 http:/dx.doi.org/10.4271/pt-178 Information contained in this work has been obtained by SAE International from sources believed to be reliable. Ho
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9、00 Commonwealth Drive Warrendale, PA 15096 E-mail: CustomerServicesae.org Phone: +1.877.606.7323 (inside USA and Canada)+1.724.776.4970 (outside USA) Fax: +1.724.776.0790v Table of Contents Introduction . 1 1. An Exergy-Based Methodology for Decision-Based Design of Integrated Aircraft Thermal Syste
10、ms (2000-01-5527) . 3Figliola, R., and Tipton, R. 2. Dynamic Thermal Management System Modeling of a More Electric Aircraft (2008-01-2886). 13McCarthy, K., Walters, E., Heltzel, A., Elangovan, R., et al. 3. Facilitating the Energy Optimization of Aircraft Propulsion and Thermal Management Systems th
11、rough Integrated Modeling and Simulation (2010-01-1787) 21Maser, A., Garcia, E., and Mavris, D. 4. Power Thermal Management System Design for Enhanced Performance in an Aircraft Vehicle (2010-01-1805) . 35Bodie, M. 5. Integrated Electrical and Thermal Management Sub-system Optimization (2010-01-1812
12、) 45Bodden, D., Eller, B., and Clements, S. 6. Thermal Management Investigations for Fuel Cell Systems On-Board Commercial Aircraft (2013-01-2274) 51Vredenborg, E., and Thielecke, F. 7. Advantages of the Dynamic Simulation for the Thermal Management Systems Design (2014-01-2152) 63Del Valle, P., and
13、 Blazquez Munoz, P. 8. A Thermal Management Assessment Tool for Advanced Hypersonic Aircraft (921941) . 71Issacci, F., Wassel, A., Farr, J., Wallace, C., et al. 9. Model-Based Thermal Management Functions for Aircraft Systems (2014-01-2203) . 89Schlabe, D., and Lienig, J.10. A Modeling Approach for
14、lntegrated Thermal Management System Analysis of Aircraft (971242) . 99Van Griethuysen, V. J., lssacci, F., and Farr, J., Jr. About the Editor 1091 Introduction The simultaneous operation of all systems generating, moving, or removing heat on an aircraft is simulated using integrated analysis, which
15、 is called Integrated Energy System Analysis (IESA) for this book. Multiple terms are used in the literature to describe this type of analysis, The purpose of this analytical modeling is to understand, optimize, and validate more efficient system architectures for removing or harvesting the increasi
16、ng amounts of waste heat generated in commercial and military aircraft. In the commercial aircraft industry, IESA is driven by the desire to minimize airplane operating costs associated with increased system weight, power consumption, drag, and lost revenue as cargo space is devoted to expanded cool
17、ing systems. In military aircraft, IESA is also considered to be a key enabler for the successful implementation of the next-generation jet fighter weapons systems and countermeasures. In 2014, the Aerospace Systems Directorate of the U.S. Air Force Research Laboratory launched the Center for Integr
18、ated Thermal Management of Aerospace Vehicles due to concerns over thermal issues being a limiting factor in the performance of future military aircraft. This book contains a selection of papers relevant to aircraft thermal management IESA published by SAE. The papers cover both recently developed g
19、overnment and industry- funded thermal management IESA, such as the Integrated Vehicle Energy Technology (INVENT) program, and older published papers still relevant today, which address modeling approaches. While the modeling discussed primarily refers to military aircraft, the same tools and method
20、s may be adapted for commercial aircraft simulations following minor modifications. Additional information on the closely related topic of Aircraft Thermal Management is available from SAE AIR 5744 issued by the AC-9 Aircraft Environmental System Committee and the book, Aircraft Thermal Management:
21、Systems Architectures. SAE AIR 5744 defines the discipline of aircraft thermal management system engineering, while Aircraft Thermal Management: Systems Architectures discusses the more efficient means of managing aircraft heat generation being developed using the types of analysis methods and progr
22、ams discussed in this book.23 2000-01-5527 An Exergy-Based Methodology for Decision-Based Design of Integrated Aircraft Thermal Systems R. S. Figliola Clemson University Robert Tipton Lockheed-Martin Copyright 2000 by SAE International, and the American Institute in Aeronautics and Astronautics, Inc
23、. All rights reserved. ABSTRACT This paper details the concept of using an exergy-based method as a thermal design methodology tool for integrated aircraft thermal systems. An exergy-based approach was ap- plied to the design of an environmental control system (ECS) of an advanced aircraft. Concurre
24、ntly, a traditional energy- based approach was applied to the same system. Simplified analytical models of the ECS were developed for each method and compared to determine the validity of using the exergy approach to facilitate the design process in optimizing the overall system for a minimum gross
25、takeoff weight (GTW). The study identified some roadblocks to assessing the value of using an exergy-based approach. Energy and exergy methods seek answers to somewhat different questions making direct comparisons awkward. Also, high entropy generating devices can dominate the design objective of th
26、e exergy approach. Nonetheless, exergy methods do provide information to aid design providing a ready estimate for efficiency on a compo- nent and system basis. The results from the two analyses did provide similar while not exact solutions. While the paper will illustrate the methodology and its im
27、plementation, further progress is necessary to validate the hypothesis that exergy- based methods are advantageous for the design of integrated systems. INTRODUCTION In thermal systems, decisions are based in part on the thermo- dynamic behavior of the component or system. Traditional design procedu
28、res use an energy-based approach for decision- making. Essentially this is a thermodynamic first law analysis. Exergy-based methods deal with the simultaneous application of the thermodynamic principles of the first law and second law to component or system design. Exergy analysis yields an optimal
29、solution based on an objective of entropy generation minimization. Energy-based methods are built on the funda- mental concept that energy flows into and out of a system through heat transfer, work, and mass flow. That energy must be conserved is the basic premise of the first law. On the other hand
30、, exergy represents the ability to do work or, put in a different way, the ability to bring about a desired change. Exergy is not conserved and, in fact, is partially or totally de- stroyed. The amount of exergy destroyed is proportional to the amount of entropy generated. It is the destroyed exergy
31、 that brings about the component or system inefficiency. Hence, a design process based on minimizing entropy generation re- duces exergy destruction to improve efficiency. Exergy-based methods applied to the design of aircraft inte- grated systems have been discussed as being advantageous to traditi
32、onal methods. The approach has been applied to com- ponents and to land-based power plant design e.g. 1-3. Tip- ton et al. 4 first applied exergy methods to the environmental control system of an aircraft and this paper follows up on that study. By looking at the irreversibilities associated with th
33、e entropy generation of each component, an attempt is made to meet design objectives that make best use of available energy. An attractive feature of the method comes from entropy as a property. Irreversibility within a system is related to the sum of the entropy generated by each component in the s
34、ystem. Constraints, such as size or weight, are readily imposed. How- ever, the demonstration of a complete optimized design of an aircraft system using exergy methods has not been docu- mented. The original motivation for this work was prompted by a study to evaluate the aircraft-level impact of us
35、ing spray cooling technology in an avionics chassis, which was part of the envi- ronmental control system (ECS) of an advanced aircraft 4. In particular, the aircraft level impacts of this new cooling tech- nology were to be evaluated. While evaluation of this technol- ogy is not the focus of this p
36、aper, the avionics chassis remains within the model and its impact will be studied. More recently, participants from an Air Force sponsored workshop 5 identified several unresolved questions of im- portance in moving towards an innovative, fully integrated4 design methodology for air vehicles. Of th
37、ese, an unambigu- ous demonstration of exergy-based methodology advantages at the system and aircraft levels was a priority. This paper de- tails the concept of using an exergy-based method as a thermal design methodology tool for integrated aircraft thermal sys- tems. APPROACH A conventional energy
38、 analysis of an integrated system in- volves a first law, thermodynamic energy analysis performed on a component-by-component basis throughout the system. Components included consist of heat exchangers including ram air loss, turbomachine devices, throttle devices, sprayers, combustors, and plumbing
39、. Changes in the system properties are related to changes in energy. System performance is de- termined for a given set of operating conditions. The optimal design of the system is determined by variation of appropriate parameters in an effort to minimize an objective function, such as to minimize e
40、nergy usage (or equivalently for aircraft, to minimize the gross takeoff weight). For example, in aircraft systems an optimal design may correspond to minimizing fuel or weight or it can be related back to minimizing drag. The controlling variables of the design process reduce to weight, engine powe
41、r extraction to drive the necessary components, and drag, with constraints such as size imposed. A final re- view is made to ensure that the optimum design satisfies all the performance requirements of the system for a given appli- cation. Because this method is the conventional analysis, we will no
42、t go into detail on its approach. An exergy analysis of an integrated system incorporates sec- ond law concepts into the analysis on a component-by- component basis in terms of each components entropy gen- eration. Entropy generation relates to losses or energy waste, that is, irreversibility. Chang
43、es in the system can be related to changes in entropy. The attractive feature of such analysis lies in the physical attributes of entropy as a property: The total entropy generation of each subsystem is simply the sum of the individual entropy generations of each component within the particular subs
44、ystem (6). Similarly, the total entropy genera- tion of the overall system is determined from the summation of the individual entropy generations of each subsystem. Therein lies an advantage to this method in that inefficiency is readily quantified. So this type of analysis results in a common measu
45、rement of inefficiency for each of the components in the system, thus disclosing the problem areas of the system that can stand improvement. It can be expanded to include manu- facturing and maintenance efficiencies. Further, it provides a basis to compare systems that are quite different in a physi
46、cal sense. An objective for the optimal design is to minimize the entropy generation (or minimize exergy destruction) of the system. For purposes of estimating component or subsystem irreversi- bility for open systems, it is convenient to write the second law in the form of entropy generation 7 as w
47、here is mass flow rate, s is entropy, T is temperature, and Q is heat transfer rate. This defines the rate of entropy genera- tion across the component or subsystem being evaluated. Within all connecting ducts and pipes, entropy generation is related to pressure drop and friction losses and can be m
48、odeled asp T Sgen = and within heat exchangers by a form of 2 in out 1 in out 2 in out p1 in out p gen ) p p Rln( ) p p Rln( ) T T ln( c) T T ln( c S += where subscripts 1 and 2 refer to the mass streams. The rate of thermodynamic irreversibility in an engineering system is directly related to lost
49、or wasted useful power. The system irreversibility is related to the net entropy generation rate for the system and a reference temperature, T o(e.g. envi- ronment absolute temperature) 7. It will suffice to calculate the rate of entropy generation in comparing various system configurations for an optimal solution. Thus, by estimating the entropy generation of a component it is possible to determine its contribution to the total irreversibility of the system 8. To accomplish the entropy generation analysis of an overall system, an entropy generation n
