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Educating Undergraduate Mechanical Engineering Students About Exergy Analysis

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Conference

2015 ASEE Annual Conference & Exposition

Location

Seattle, Washington

Publication Date

June 14, 2015

Start Date

June 14, 2015

End Date

June 17, 2015

ISBN

978-0-692-50180-1

ISSN

2153-5965

Conference Session

ECCD Applications in Energy and Thermodynamics

Tagged Division

Energy Conversion and Conservation

Page Count

12

Page Numbers

26.570.1 - 26.570.12

DOI

10.18260/p.23908

Permanent URL

https://peer.asee.org/23908

Download Count

166

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Paper Authors

biography

Farshid Zabihian West Virginia University Inst. of Tech.

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Farshid Zabihian, Ph.D.
Assistant Professor
Department of Mechanical Engineering
West Virginia University Institute of Technology

Education:
Ph.D., Mechanical Engineering,Ryerson University, 2011
M.S. Mechanical Engineering, Iran University of Science and Technology, 1998
B.S. Mechanical Engineering, Amir Kabir University of Technology, 1996

Authored or coauthored more than 70 papers in Journals and peer-reviewed conferences.

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Abstract

Educating Undergraduate Mechanical Engineering Students about Exergy AnalysisThe concept of availability and exergy analysis is one of the most abstract ideas inthermodynamics and undergraduate mechanical engineering students have a difficult time tounderstand it. Unfortunately usually existing textbooks cannot help students much when it comesto exergy. This paper presents the approach that the author has developed to teach concept ofexergy (not just mathematical formulation).The first law of thermodynamics deals with amount of energy transfer regardless of its form andconditions. This approach, however, is not appropriate for some applications. For instance, someforms of energy are more valuable than others. For example, work is more valuable than heatbecause work can be completely converted to heat but the efficiency of generating work fromheat is always lower than unity, with the maximum efficiency in the Carnot cycle. Similarly, thesame amount of thermal energy at high temperature is more valuable than thermal energy at lowtemperature because the thermal energy at higher temperature can be converted to work at ahigher efficiency in a thermal engine (e.g. Carnot cycle) than that of thermal energy at lowtemperature. Based on the first law of thermodynamics, 1 kJ of electricity, chemical energy offuel, thermal energy at 400°C, and thermal energy at 50°C are basically equal. But in reality theireconomic values are not the same. Electricity can be converted to mechanical work with veryhigh efficiency (higher than 90%) and fuel can be used to produce work at relatively highefficiency (up to 60% in modern power plants) but for thermal energy at 400°C and 50°C,potential to generate work is much limited and is bounded by the efficiency of the Carnot cycle(for a heat sink temperature of 27°C, this maximum theoretical efficiency is equal to 55.4% and7.1%, respectively). Therefore, it is vital to find a methodology to evaluate thermal systems notonly based on amount of energy conversion but also the actual value of energy.

Zabihian, F. (2015, June), Educating Undergraduate Mechanical Engineering Students About Exergy Analysis Paper presented at 2015 ASEE Annual Conference & Exposition, Seattle, Washington. 10.18260/p.23908

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