**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.[37%]

__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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Engineering Thermodynamics by
Israel Urieli is licensed under a
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