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Unformatted text preview: ME 200: Thermodynamics I Lecture 23: Temperature Scales and
Maximum Performance Measures
Prof. Sojka
Summer 2011 In this Lecture …
• We will study: ME 200 – Temperature scales and Maximum
performance measures 8 July 2011 2 Temperature Scale • For reversible cycles, Carnot showed
for absolute temperatures Q
T C
=C TH QH rev
cycle ME 200 • Absolute temperature scale is
independent of the properties of the
substance.
8 July 2011 3 Carnot
efficiency Maximum performance measures
(reversible processes)
• Power cycles
T
η max = 1 − C
TH • Refrigeration cycles ME 200 TH
γ max =
TH − TC TC
β max =
TH − TC • Heat pump cycles 8 July 2011 4 Example TC
β max =
TH − TC ME 200 QC
β=
Wcycle QC = 1500 kJ, Wcycle = 150 kJ.
QC = 1400 kJ, QH = 1600 kJ.
QH = 1600 kJ, Wcycle = 400 kJ.
β = 5. Wcycle = QH − QC irreversible reversible impossible A refrigeration cycle operating between two
reservoirs receives energy QC from the one at TC =
280 K and rejects energy QH to one at TH = 320 K.
For each of the following cases determine whether
the cycle operates reversibly, irreversibly, or is
impossible:
–
–
–
– 8 July 2011 5 Closure
• In this lecture, we talked about: ME 200 – Temperature scales
– Maximum performance measures 8 July 2011 6 Next Lecture • In the next lecture, we are going to talk
about: ME 200 – Carnot Cycle
– Clausius Inequality October 20th, 2010 7 ...
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This note was uploaded on 09/26/2011 for the course ME 200 taught by Professor Gal during the Summer '08 term at Purdue.
 Summer '08
 GAL

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