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This document discusses geothermal power plants and provides examples of calculating key metrics like turbine efficiency and power output. It includes 5 example problems calculating values like turbine inlet temperature, specific work output, turbine efficiency, and power generation based on given reservoir conditions, flow rates, and operating pressures and temperatures at different points in geothermal power systems. The examples illustrate how to model geothermal power cycles and determine performance parameters using a Mollier chart and thermodynamic calculations.

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Juan Ponce Manríquez
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233 views1 page

Page 71 PDF

This document discusses geothermal power plants and provides examples of calculating key metrics like turbine efficiency and power output. It includes 5 example problems calculating values like turbine inlet temperature, specific work output, turbine efficiency, and power generation based on given reservoir conditions, flow rates, and operating pressures and temperatures at different points in geothermal power systems. The examples illustrate how to model geothermal power cycles and determine performance parameters using a Mollier chart and thermodynamic calculations.

Uploaded by

Juan Ponce Manríquez
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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150 Geothermal Power Plants: Principles, Applications, Case Studies and Environmental Impact

of 182 C. The reservoir conditions are known to be 32.3 bar and 238 C.
The turbine exhaust pressure (condenser pressure) is 0.13 bar.
(a) Sketch the location of the reservoir and turbine-inlet state points on a
Mollier chart (h-s); the states should be placed on a scale-drawn portion
of the h-s diagram. What do you observe about the enthalpy of these two
states? What do you notice about these values relative to the maximum
enthalpy along the saturated vapor line?
(b) On the same diagram, locate the turbine exhaust state. Calculate the
turbine isentropic expansion efficiency, ηt. Calculate the overall geothermal
energy utilization efficiency, ηu, based on (i) reservoir and (ii) turbine-inlet
conditions. A sink temperature of 48 C is appropriate for Unit No. 6.
7.3 A dry-steam geothermal plant receives saturated steam at a temperature of
180 C. The condenser operates at 50 C and the local dead-state temperature
is 20 C. The turbine obeys the Baumann rule; assume 85% for the dry expan-
sion efficiency. Calculate the following:
(a) The actual turbine isentropic efficiency.
(b) The specific work output of the turbine in kJ/kg.
(c) The net utilization efficiency if 5% of the turbine output is needed for all
parasitic loads.
7.4 A dry-steam reservoir produces saturated vapor at the maximum enthalpy point.
By adjustment of the wellhead valve, the steam is throttled to lower pressures.
A pressure P1 5 0.800 MPa is chosen as the wellhead and turbine inlet pressure
(ignore pressure losses in steam piping). At this point the well produces 15 kg/s.
The turbine exhausts to a condenser at a pressure P2 5 10 kPa.
(a) Find the turbine inlet temperature in  C.
(b) Calculate the specific work output of the turbine in kJ/kg.
(c) Calculate the actual turbine isentropic efficiency.
(d) Calculate the gross power output for the turbine in MW.
7.5 A dry-steam well is characterized by a closed-in pressure of P1 5 360 lbf/in2,
a and saturated vapor. The wellhead valve is set at P2 5 150 lbf/in2, a at which
condition the well flows 200,000 lbm/h. You may assume the turbine is adiabatic
and has a constant isentropic efficiency of 75%.
(a) Calculate the power in MW that the turbine will generate under the
following two cases: (i) there is no condenser and the turbine exhausts to
the atmosphere at 1 atm, and (ii) there is a condenser that has a pressure
of 4 in Hg.
(b) Calculate the utilization efficiency in both cases, based on the closed-in
condition of the geofluid.

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