**Problem 8.1 - A 10 MPa Steam Power Plant with an
Open Feedwater Heater**

Consider the steam power plant with an open 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 9 stations on the
diagram.

Using
the conditions shown on the diagram above and values obtained from
the **Steam
Tables**:

a) determine the enthalpy values at all nine stations. Indicate these values on the axis of the

*P-h*diagram above and check them for feasibility.b) determine the mass fraction [y] of steam bled from the turbine set at station (2).[y = 0.207]

c) determine the thermal efficiency [η

_{th}] of this power plant. (You may neglect the pump work for this evaluation.) [39%]d) Consider the condition that the throttling valve is completely shut off, and that the state at station (9) is reduced to 10 MPa, 40C. Determine the thermal efficiency [η

_{th}] under this condition.[35%]

__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.
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