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C                Heat capacitance

c              Specific heat at constant pressure

m               Mass

p                Pressure

Q               Heat

r              Pressure ratio

r              Highest-to-lowest temperature ratio

S                Entropy

S*              Normalized entropy generation

s                Specific entropy

T                Temperature

TEH             Highest temperature of engine

TEL              Lowest temperature of engine

TH              Adiabatic combustion temperature

Th,in            Hot stream inlet temperature

Th,out          Hot stream outlet temperature

Tl,in             Cold stream inlet temperature

Tl,out           Cold stream outlet temperature

TL               Temperature of ambient/low temperature reservoir

W               Work

W*              Normalized wor


Greek letters

γ                 Specific heat ratio

η                 Efficiency

π                 TL/TH



CV              Carnot vapor cycle

Gen           Generation

H                High temperature reservoir

h                 Hot stream

in                Inlet

l                  Cold stream

L                 Low temperature reservoir

max           Maximum

min            Minimum

MN             Modified Novikov power plant model

N                Novikov’s power plant model

out             Outlet

opt             Optimum

SGen,min       Condition at minimum entropy generation

th               Thermal

tot              Total

Wmax           Condition at maximum work output

ηth,max        Condition at maximum thermal efficiency




Endo-reversible engines

Irreversible heat engines





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