7-5 T-S DIAGRAM

Internally reversible process dS int rev

Q

T

δ =

( )7-4 ⇒ Qδ TdS= ( )7-14

Q

2

1

TdS= ∫ ( )7-15

q

2

1

Tds= ∫ ( )7-17

Isothermal Process

Q ( )0 2 1T S S= ⋅ − ( )7-18

q ( )0 2 1T s s= ⋅ − ( )7-19

7-4 Isentropic process ( S const= )

Example 7-6 Carnot Cycle

net ,in

Q net ,out

W=

net ,out

W H L

Q Q= −

h-s diagram (Mollier diagram, p.345) is useful for analysis of steady-flow devices

T

S

Area Q=

1S

2S

1

2

Internally

reversible

process

Heat transfer during

the internally

reversible process

reversible adiabatic

isentropic process

�

isentropic process

is associated with

internally reversible

adiabatic process

w h∆=For adiabatic steady-flow devices:

nozzles, turbines, compressors, etc.

Richard Mollier (1863 1935)−

For internally

reversible process

T

S

Q 0=

1 2S S=

1

2

T

S

net ,out H LW Q Q= −

1 4S S=

2 3S S=

1 2

HT

4 3L

T

HQ

LQ

T

S

Q

1S

2S

1 2

isothermal

process is

internally

reversible0

T

q T s∆= For isothermal processes

h

s

s∆

1s

2s

1

2

h∆measure

of work

output

measure of the

irreversibilities

1h

2h