EGR 334 ThermodynamicsChapter 4: Review

Lecture 19: Integrated Systems and System Analysis Quiz Today?

Today’s main concepts:Review of Mass balance equationReview of Continuity equationReview of Energy balance equationReview of Control Volume applications

Reading Assignment:

Homework Assignment:

• Read Chapter 5, All Sections• Come prepared to participate in a classroom discussion.

Problems from Chap 4: 94, 100, 106

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Terms for Chap 5 Class Discussion :

• Spontaneous Heat Transfer•Clausius Statement•Kelvin-Planck Statement• Entropy Statement• Irreversible vs. Reversible• Internally Reversible Process•Carnot Corollaries•Carnot Efficiency•Max. heat pump efficiency•Max. refrigeration cycle COP•Carnot Cycle•Clausius Inequality

You may want to create a summary sheet to help you discuss each of the concepts.

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em

CVdm

dtim

Mass Rate Balance:

Energy Rate Balance:

e em e

CVdE

dti ime

Q W

Review: For a Control Volume:

2 2cv V V

2 2i e

cv cv i i i e e e

dEQ W m h gz m h gz

dt

cvin exit

i i

dmm m

dt

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em

CVdm

dtim

Mass Rate Balance:

Energy Rate Balance:

e em e

CVdE

dti ime

Q W

Review: For a Control Volume:

2 2V V0

2 2i e

cv cv i i i e e eQ W m h gz m h gz

0 in exiti i

m m SS

SS

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Simplified CV Models:

Nozzles Diffuser

PumpCompressor

Throttling Valve

2 210 ( ) (V V )

2i e i eh h

eiCV hhmW

ei hh

Turbine

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Control Volume Applications:

BoilerDirect Contact Heat Exchanger

Tube Heat Exchanger

1 1fluid fluidi em m

1 1 1 2 2 20

fluid fluid fluid fluid fluid fluidi e i em h h m h h 0Hot Hot Cold Coldi i i i e em h m h m h

Hot Coldi i em m m Mass balance:

Energy balance:

Mass balance:

Energy balance:

2 2fluid fluidi em m

Integrated Systems:

Power Plant Cycle

1. Condenser

2. Throttling valve/ Expander

3. Evaporator4. Compressor

WCV

QCV

QCV

Refrigeration Cycle

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Workout Problem 1:A residential air conditioning system operates at steady state. Refrigerant-22 circulates through the components of the system. Property data at key locations are given on the figure. If the evaporator removes energy by heat transfer from the room air at a rate of 600 Btu/min, determinea) the rate of heat transfer between the compressor and the surroundings in Btu/min b) the rate of heatreleased to the outside airc) the coefficient of performance.

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end of Lecture 19 Slides