Consider a regenerative steam rankine cycle with a single open feedwater heater. at the entrance to the turbine the steam is at 17.5 mpa and 650°c. 20% of the steam is extracted from the turbine at 1.4 mpa and directed to the open feedwater heater directly, while the remaining steam is further expanded to 20 kpa before being sent to the condenser unit. the steam is condensed at 20 kpa to saturated liquid conditions before being pumped to higher pressure and directed to the open feedwater heater. after mixing in the open feedwater heater, the combined stream is pumped to high pressure and directed to the boiler to vaporize the steam.

(a) what is the degree of sub-cooling of the liquid at the exit to the open feedwater heater (i. e. what is the temperature difference between the liquid leaving the open feedwater heater and a saturated liquid at the same pressure)?

(b) what is the total work output from the turbine (report per unit mass flowing through the boiler)?

(c) what is the overall thermal efficiency?