Question

hi please provide the graph and calculation. design an appropriate plot, show that it's not practical to have more than two reheat stages (take at least three reheat pressures between 2 to 12 MPa).reheated Rankine power cycle uses water as working fluid. The first stage turbine 's inlet conditions are 14MPa, and 600oC.All turbines are known as isentropic 85 percent efficiency,the pump is assumed as an isentropic pump.If the maximum temperature is maintained at 600oC and the condenser pressure is 6 kPa

Answer 1

The single reheat in a modern power
plant improves the cycle efficiency by 4 to
5% by increasing the average
temperature at which heat is transferred
to the steam.
The average temperature during the
reheat process can be increased by
increasing the number of expansion and
reheat stages. As the number of stages is
increased, the expansion and reheat
processes approach an isothermal
process at the maximum temperature.
The use of more than two reheat stages
is not practical. The theoretical
improvement in efficiency from the
second reheat is about half of that which
results from a single reheat.

Let us see

For two stages of reheating

The efficiency comes out to be 33.690%

For three stages of reheating