Gas Power Cycles Prof. U.S.P. Shet , Prof. T. Sundararajan and Prof. J.M . Mallikarjuna

Indian Institute of Technology Madras

4.9 Lenoir Cycle:

Volume

1

2

3

(a)

Entropy

1

2

3

(b)

Fig.4.9. Lenoir cycle on p-v and T-s diagrams

Gas Power Cycles Prof. U.S.P. Shet , Prof. T. Sundararajan and Prof. J.M . Mallikarjuna

Indian Institute of Technology Madras

The Lenoir cycle consists of the following processes:

• Process 1-2: Constant volume heat addition

• Process 2-3: Reversible adiabatic expansion

• Process 3-4: Constant pressure heat rejection.

• No compression process.

The thermal efficiency can be derived as follows:

( ) ( )( )

v 2 1 p 3 1th

v 2 1

C T - T - C T - THeat added - Heat rejected = = Heat added C T - T

η

3 1th

2 1

T - T = 1 -

T - T⎛ ⎞

η γ ⎜ ⎟⎝ ⎠

( )

2p

1

2 p 1

- 1 - 1 - 11 - 13 3 1

p2 2 2 1

PLet, = r = Pressure ratio

PT = r T

T P P 1 = = = r T P P

γ γ γγ γ γ

γ⎛ ⎞ ⎛ ⎞ ⎛ ⎞

=⎜ ⎟ ⎜ ⎟ ⎜ ⎟α⎝ ⎠ ⎝ ⎠ ⎝ ⎠

( ) ( ) ( )1 1 1 - 1 - 1

3 2 p 1 p p 1 pT = T r = T r r = T rγ γ γ

( )

1

p

thp

r - 1

= 1 - r - 1

γ⎛ ⎞⎜ ⎟γ⎜ ⎟⎝ ⎠η