Analysis of Power Generation Cycles P M V Subbarao Professor Mechanical Engineering Department Development of Techno-economically Feasible Thermodynamic Model

Schematic of Rankine & Brayton cycles

Global Accounting of Energy Interactions First law for a cycle:

Net Power output (Income) of A Cycle

Basic Expenditure in A cycle

First Law Analysis & Figure of Merit for the Cycle

Ideal Rankine Cycle : P-h Diagram pmax=17Mpa =42.05% 1 2 3 4 Tmax=5500C 1 2 3 4 pmax=5Mpa =37.8%

Ideal Rankine Cycle : P-h Diagram Tmax=5500C Tmax=4500C Tmax=6000C 1 2 3 4

Selection of Optimum Boiler Pressure Tmax = 450 oC h Pressure, MPa

pmax=10MPa

Parametric Study of Rankine Cycle D.S.S. 3000C h P max

Parametric Study of Rankine Cycle 23.5MPa 22MPa 18MPa 10MPa 6MPa D.S.S. 3MPa h 1MPa Tmax

Progress in Rankine Cycle Year 1907 1919 1938 1950 1958 1959 1966 1973 1975 MW 5 20 30 60 120 200 500 660 1300 p,MPa 1.3 1.4 4.1 6.2 10.3 16.2 15.9 24.1 Th oC 260 316 454 482 538 566 565 Tr oC -- FHW 2 3 4 6 7 8 Pc,kPa 13.5 5.1 4.5 3.4 3.7 4.4 5.4 h,% ~17 27.6 30.5 35.6 37.5 39.8 39.5 40

Layout of A Modern Power Plant

Brayton Cycle : Working with Single Phase –Substance Qin Qout Wout

Brayton Cycle for Power Generation 1-2 Adiabatic compression (in a compressor) 2-3 Constant pressure heat addition 3-4 IAdiabaticexpansion (in a turbine) 4-1 Constant pressure heat rejection

Thermodynamic Analysis of Adiabatic Compression For an infinitesimal compression:

Adiabatic Process by an Ideal Gas For an infinitesimal compression of perfect gas:

Model for infinitesimal Adiabatic Process by a perfect Gas