Write a computer program or use an equation solver or spreadsheet to carry out a parametric study of the isentropic Rankine cycle with regeneration given in given Example, part b. Allow the regenerator pressure p5s to vary from 1.00 to 200. psia (this simulates opening a valve in the regenerator steam line from the turbine). Maintain the regenerator outlet state as a saturated liquid (i.e., set h6 = hf(p5s)), because if h6 f(p5s), the regenerator is not operating as effectively as possible; and if h6 > hf(p5s), there will be vapor at the entrance of the boiler feed pump and its performance will be seriously degraded.
a. Determine the values of p5s and mass fraction y that maximize the cycle efficiency.
b. Produce a plot of cycle efficiency ηT and mass fraction y on the y-axis vs. regenerator pressure p5s on the x-axis. As part of this solution, note that, when p5s is equal to the turbine inlet pressure (200. psia) or the condenser inlet pressure (1.00 psia), the regenerator has no effect and the cycle efficiency is the same as without regeneration (i.e., 29.7%).
Example :
A two-stage steam turbine receives dry saturated steam at 200. psia. It has an interstage pressure of 80.0 psia and a condenser pressure of 1.00 psia. Determine
a. The isentropic Rankine cycle thermal efficiency of the system without regeneration present.
b. The isentropic Rankine cycle thermal efficiency of the system and the mass fraction of regeneration steam required with an open loop boiler feedwater regenerator at a pressure of 80.0 psia.