Prof. Dr. Almıla Yazıcıoğlu
Methodology of Solving Thermodynamics Problems
(adapted from M.J. Moran et al., Principles of Engineering
Thermodynamics, 8th ed., Wiley, 2015)
1 Known:
Read the problem carefully and think about it.
State, in your own words, what is known.
2 Find:
State, in your own words, what is to be determined.
3 Schematic and Given Data:
Draw a sketch of the system to be considered. Is it closed or open?
Carefully identify the boundary.
Label the sketch with useful information from the problem statement.
Write all property values given or may be required for calculations.
Sketch appropriate property diagrams (p-v, T-v, p-T as necessary),
locating key state points and indicating, if possible, the processes
executed by the system.
4 Engineering Model:
List all simplifying assumptions and idealizations made to reduce the
system to one that is manageable/solvable. You may note these on the
sketches.
5 Analysis:
Using your assumptions and idealizations, reduce the appropriate
governing equations and relationships to forms that will produce the
desired results.
Work with equations (keep them in symbolic form) as long as possible
before substituting numerical data.
Think about reduced equations, to determine what additional data may
be required. Then identify the tables, charts, or property equations that
provide the required values.
Substitute numerical values into the equations and check that a
consistent and appropriate set of units is being employed.
Perform the needed calculations.
Finally, consider whether the magnitudes of the numerical values are
reasonable and the algebraic signs associated with the numerical values
are correct.