Problem 8.2 - Steam Power Plant with a Closed Feedwater Heater

Consider the steam power plant with a closed feedwater heater operating under the conditions shown in the following diagram:

Carefully draw the complete cycle above on the pressure-enthalpy [P-h] diagram provided below, indicating clearly all 8 stations on the diagram.

Using the conditions shown on the diagram above and values obtained from the steam tables, determine

• a) the enthalpy values at all eight stations
• b) the mass fraction [y] of steam bled from the turbine set at station (2). (State your assumptions in developing the equation for the mass fraction.)
• c) the thermal efficiency [_th] of this power plant. (You may neglect the pump work for this evaluation.)

Note: Justify all values used and derive all equations used starting from the basic energy equation for a flow system, and basic definition of thermal efficiency of a heat engine.