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Pressure drop prediction models

Pressure drop prediction models. Garimella et al. (2005) Considered parameters Single-phase pressure gradients Martinelli parameter Surface tension parameter Fluid and geometric properties. Pressure drop prediction models. Garimella et al. (2005).

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Pressure drop prediction models

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  1. Pressure drop prediction models • Garimella et al. (2005) • Considered parameters • Single-phase pressure gradients • Martinelli parameter • Surface tension parameter • Fluid and geometric properties Heat and Mass Transfer Laboratory

  2. Pressure drop prediction models • Garimella et al. (2005) Void fraction is calculated using the Baroczy (1965) correlation: Liquid and vapor Re values are given by: Heat and Mass Transfer Laboratory

  3. Pressure drop prediction models Liquid and vapor friction factors: Therefore, the single-phase pressure gradients are given and the Martinelli parameter is calculated: • Garimella et al. (2005) Heat and Mass Transfer Laboratory 3

  4. Pressure drop prediction models Liquid superficial velocity is given by: This velocity is used to evaluate the surface tension parameter: • Garimella et al. (2005) Heat and Mass Transfer Laboratory 4

  5. Pressure drop prediction models Interfacial friction factor: Laminar region: Turbulent region (Blasius): • Garimella et al. (2005) Heat and Mass Transfer Laboratory 5

  6. Pressure drop prediction models The pressure gradient is determined as follows: • Garimella et al. (2005) Heat and Mass Transfer Laboratory 6

  7. Heat transfer prediction models • Bandhauer et al. (2005) • Considered parameters • Pressure drop • Dimensionless film thickness • Turbulent dimensionless temperature • Pr • Fluid and geometric properties • Range / applicability • 0.4 < D < 4.9 mm • R134a • 150 < G < 750 kg/m2s Heat and Mass Transfer Laboratory

  8. Heat transfer prediction models Interfacial shear stress: Friction velocity is now calculated: • Bandhauer et al. (2005) Heat and Mass Transfer Laboratory 8

  9. Heat transfer prediction models Film thickness is directly calculated from void fraction: This thickness is used to obtain the dimensionless film thickness: • Bandhauer et al. (2005) Heat and Mass Transfer Laboratory 9

  10. Heat transfer prediction models Turbulent dimensionless temperature is given by: Therefore, the heat transfer coefficient is: • Bandhauer et al. (2005) Heat and Mass Transfer Laboratory 10

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