Modification%20of%20Capacity%20Ratio%20in%20Simple%20HXs

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Modification of Capacity Ratio in Simple HXs

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

Split the flows for better Perfromance.
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Annular flow in series Tubular Flow in Parallel
Counter Flow
HX-
HX-
Tubular stream mass flow is equally split between
the two units.
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Flow Parameters
Annular flow Hot Fluid Tubular flow Cold
Fluid.
Parameter HX 1 HX 2
Hot fluid inlet temperature Th,in1 Th,in2
Hot fluid outlet temperature Th,ex1 Th,ex2
Cold fluid inlet temperature Tc,in1 Tc,in2
Cold fluid outlet temperature Tc,ex1 Tc,ex2
Hot fluid flow rate
Cold fluid flow rate
Surface area A/2 A/2
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Temperature Variation
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Analysis of HX1
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Analysis of HX2
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Analysis of Global ASTP HX
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New Dimensionless Parameters
For same value of U in both the HXs
Cold (Tubular) stream in parallel
Hot (annular) stream in series
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For simple counter flow heat exchanger
For HX1 of ASTP
For HX2 of ASTP
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Mean Temperature of Global ASTP
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For two level ASTP
For n level ASTP
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Two level Annular flow in series Tubular Flow
in Parallel
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n level Annular flow in series Tubular Flow in
Parallel
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For simple counter flow heat exchanger
For n level ASTP
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n
F
Pavg
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Comparison