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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
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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?