GAS POWER CYCLES 681

dharm

\M-therm\Th13-6.pm5

∴ ηcycle = Net

Heat

work

added

()()

()

=

−− −

−

mc T T mc T T

mc T T

p p

p

34 21

32

= ()(.)

(.)

1251 750 500 4 300

1251 500 4

−− −

−

= 0.4 or 40%. (Ans.)

L

N

M

M

M

Check;

() ()

cycle .4

.4

η γ

γ

=− F − =− =

HG

I

KJ

(^1) −
1
1
1
6
1 11
1
rp
0.4 or 40%. (Ans. )
O
Q
P
P
P
Example 13.33. A gas turbine is supplied with gas at 5 bar and 1000 K and expands it
adiabatically to 1 bar. The mean specific heat at constant pressure and constant volume are
1.0425 kJ/kg K and 0.7662 kJ/kg K respectively.
(i) Draw the temperature-entropy diagram to represent the processes of the simple gas
turbine system.
(ii)Calculate the power developed in kW per kg of gas per second and the exhaust gas
temperature. (GATE, 1995)
Solution. Given : p 1 = 1 bar ; p 2 = 5 bar ; T 3 = 1000 K ; cp = 1.0425 kJ/kg K ;
cv = 0.7662 kJ/kg K
γ =
c
c
p
v

1. .7662
   0425
   0 = 1.36
   (i)Temperature-entropy (T-s) diagram :
   Temperature-entropy diagram representing the processes of the simple gas turbine system
   is shown in Fig. 13.53.
   Expansion
   in turbine
   p = 5 bar 2
   p = 1 bar 1
   3
   4
   2
   1
   Air
   compression
   T
   s
   Hea
   taddition
   Fig. 13.53