Irreversible Expansion & Multi-staging : A Superior Match.

P M V SubbaraoProfessor

Mechanical Engineering Department

Goodness Unexplored by Sir Parson……

Typical Distribution of Losses in A Stage

Enthalpy Entropy Diagram for Multistage Turbine

h

s

Turbine Inlet

Turbine Exit

Stage 1

Stage 2

Stage 3

Stage 4

Stage 5

Losses by stage and section for a 700 MW turbine.Source: Toshiba

Enthalpy Entropy Diagram for Multistage Turbine

h

s

Turbine Inlet

Turbine Exit

Stage 1

Stage 2

Stage 3

Stage 4

Stage 5

Quasi-static Approach to Irreversible Process

inp ,0

coexp ,,0

useexp ,,0

For a infinitesimal irreversible expansion process:

0000 vdpdhdsT

Irreversible Thermodynamics

An increment of entropy along an isotherm

0

0

0

00 p

Rdp

T

vdpds

0000 vdpdhdsT

0,0,00 vdpdhdsT irrgen

0,00,0 vdpdsTdh genirr

Characterization of Infinitesimal Irreversible Process