a modern approach to selecting capillary tubes andy · pdf filea modern approach to selecting...

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A Modern Approach to Selecting Capillary Tubes

Andy Schoen

Manager, Technical Services Tecumseh Products Co.

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Expansion Devices

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Hand Expansion Valve

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Short Tube Restrictor

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Automatic Expansion Valve

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Thermostatic Expansion Valve

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Electric Expansion Valve

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Capillary Tube

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Capillary Tube Flow

Bubble Point

Flow

Low ∆P High ∆P

High to Low Side ∆P

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Henry Ehrens

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Lower Ambient Temperature

Bubble Point

Flow

Low ∆P High ∆P

High to Low Side ∆P

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Higher Ambient Temperature

Bubble Point

Flow

Low ∆P High ∆P

High to Low Side ∆P

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Supco Cap Tube Chart

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J/B Cap Tube Chart

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Cap Tube Sizing Problem

• Refrigerant R-134a • Medium Temp Cooler • 1/4 HP Compressor

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Supco Cap Tube Chart

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Compressor HP vs Rating

Model Btu/h

TPA0421YXA 2050

TPA9421YXA 2075

TPA9423YXA 2320

AEA9423YXA 2390

TPB9423YAA 2675

1/4 HP R-134a Commercial Temp Compressors

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Supco Cap Tube Chart

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Wolf and Pate Correlations

1995

2002

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Characteristics Considered

• Capillary Tube Length and ID • Pressure (liquid and vapor) • Density (liquid and vapor) • Viscosity (liquid and vapor) • Specific Heat (liquid and vapor) • Surface Tension (liquid) • Amount of Subcooling • Latent Heat of Vaporization • Heat Exchange Length

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Edgar Buckingham

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Buckingham π Correlation

( )

( )

)1(23

121

321

21

...

, ... ,,

0, ... ,,

−−−

−

⋅⋅⋅=

=

=

mnamn

aa

mn

n

f

qqqf

ππππ

ππππ

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15 Different Parameters

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Wolf and Pate 2002 Correlation

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Characteristics To Determine

• Capillary Tube Length and ID • Pressure (liquid and vapor) • Density (liquid and vapor) • Viscosity (liquid and vapor) • Specific Heat (liquid and vapor) • Amount of Subcooling • Latent Heat of Vaporization • Heat Exchange Length

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NIST Refprop

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Tecumseh Web App Site

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Capillary Tube Sizing Web App

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Capillary Tube Sizing Web App

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Capillary Tube Sizing Web App

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Capillary Tube Sizing Web App

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Capillary Tube Sizing Web App

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Adiabatic vs Non-adiabatic

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Heat Exchange Length

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Heat Exchange Length

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Why use heat exchange length?

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Web App Selection using HP

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Supco Cap Tube Chart

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Web App Selection using HP

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R401A Selection using HP

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R401A Selection using HP

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R401A Selection using HP

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TPA9423YXA

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TPA9423YXA Selection at AHRI CBP

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TPA9423YXA

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TPA9423YXA Selection @ 25°F/110°F

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Cap Tube Selection using Comp Model

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Cap Tube Selection using Comp Model

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Cap Tube Selection using Comp Model

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Cap Tube Selection using Comp Model

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Supco Cap Tube Chart

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Cap Tube Selection using Comp Model

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Cap Tube Chart using Btu/h

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Questions?