A Train of Open Feed Water Heaters

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A Train of Open Feed Water Heaters

• P M V Subbarao
• Associate Professor
• Mechanical Engineering Department
• I I T Delhi

A Better Medicine for Carnot Diagnosis !!!
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Analysis of ith OFWH
Availability of Bleed steam extracted from ith
extraction
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Benefit from Bleed steam extracted from ith
extraction
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Benefit /Availability of Bleed steam extracted
from ith extraction
Fraction of Bleed steam extracted from ith
extraction
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To Find Efficiency of Regeneration cycle
Total work done by Bleed Streams
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THE OBJECTIVE FUNCTION For the present case,
the efficiency of the cycle has been taken as the
objective function to be maximized. The
efficiency of regenerative cycle depends on the
pressure at which steam is extracted for
bleeding. Maximize
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• OPTIMIZATION PROCEDURE
• Suitable method to find the value of the variable
  that maximize the objective function.
• The design variables and the constraints show
  that the system optimization is a non-linear
  programming problem.
• For such problems, a Monte Carlo simulation
  technique has been found to be quite efficient.

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Monte Carlo Method

• A Random Walk Method.
• Solve a problem using statistical sampling
• Name comes from Monacos gambling resort city

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Example of Monte Carlo Method
D
D
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Example of Monte Carlo Method
Area D2
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Increasing Sample Size Reduces Error
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Flow Chart for optimisation
Go to 1
INPUT n, Tmax , Pmax, Pmin, max no. of
generation
NO
YES
Calculate hbi, hfi at each pressure Pi and
hboi, ht1, hc1, hc2.
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Number of generation and Efficiency
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Pmax8 MPa,480oC , Pc0.04 MPa
Reheat-Regeneration cycle
Regeneration cycle
Improvement in efficiency due to reheating in a
reheat-regeneration cycle
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Thermal Efficiency
Specific Work output
Effect of no of feed water heaters on thermal
efficiency and work output of a regeneration cycle
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A Train of Closed Feed Water Heaters

• P M V Subbarao
• Associate Professor
• Mechanical Engineering Department
• I I T Delhi

A Trade of between Irreversibility and
Reliability !!!
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Closed Feed Water Heater (Throttled Condensate)
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Analysis of Regeneration through CFWH
Define y as fraction of mass extraction
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Energy Balance for CFWH
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Work done by Bleed Steam
Work done by bleed (extracted) steam
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Closed Feed Water Heaters (Throttled Condensate)
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Analysis of Regeneration through Two CFWH
Define y as fraction of mass extraction
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Energy Balance for LP-CFWH
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Energy Balance for HP-CFWH