GAS POWER CYCLES 619

dharm
\M-therm\Th13-2.pm5

For the constant volume process 2-3 :

p

T

p

T

p pT

T

2

2

3

3

3 23

2

12 3^1842

614 4

=⇒= =×.

. = 36.9 bar

Fig. 13.8

For the expansion process 3-4 :

T

T

v

v

3

4

4

3

1

=F 6 14 1

HG

I

KJ

=

−

−

γ

(). = 2.048

∴ T 4 = T^3

2 048.

=

1842

2048. = 900 K. (Ans.)

Also pv pv p p

v

(^334443) v
3
4
γγ
γ
=⇒=×
F
HG
I
KJ
or p 4 = 36.9 ×
1
6
F^14
HG
I
KJ
.
= 3 bar. (Ans.)
(ii)Process required to complete the cycle :
Process required to complete the cycle is the constant pressure scavenging.
The cycle is called Atkinson cycle (Refer Fig. 13.9).
(iii)Percentage improvement/increase in efficiency :
ηOtto = 1 –
1
()rγ−^1 = 1 –
1
() 6 14 1.− = 0.5116 or 51.16%. (Ans.)
ηAtkinson =
Work done
Heat supplied
Heat supplied Heat rejected
Heat supplied
= −

cT T c T T
cT T
cT T
cT T
TT
TT
v p
v
p
v
()()
()
()
()
()
()
32 51
32
51
32
51
32
11
−− −
−
=−
−
−
=− −
−
γ