Internal Pipe Flow Convection Coefficient

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The equation used here for the average convection heat transfer coefficient along the inside wall of a pipe with fluid flowing inside:
H = .023 * Re(D).8 * Pr n * k / D
units are shown in the table below.

Notes:

  • The units of input variable Cp are kJ/kg/deg K. For example Cp(air) = 1.005
  • Gas constant R for air is .287 kJ/kg/deg K
  • The external, or pipe wall temperature is needed to determine the Prandlt number exponent (which will be .4 if the Twall>Tfluid inlet and will be .3 if Twall>Tfluid).
  • The inlet enhancement effect on convection coefficient (as the boundary layer builds up) is not accounted for.
  • Internal fluid density is calculated using the Ideal Gas equation.
  • Turbulent flow is assumed.
  • Re(D) = 4 * massflow / pi / D / mu
  • D and L are input in mm and converted to meters internally.
  • For non-round pipes and ducts, use the hydraulic diameter for D.

    • Input Data
    Pipe Length L (mm)
    Pipe Diameter D (mm)
    Mass Flow (kg/s)
    Gas Constant, R
    Gas Conductivity, k (W/m/k)
    Gas Cp (kJ/kg/degK)
    Gas Viscosity mu (kg/m/s)
    Gas Inlet Temperature T (deg C)
    Gas Inlet Static Pressure P (kPa)
    External (or pipe wall) Temperature T (deg C)
    Output Data
    Density
    Prandtl
    Re(D)
    Mean Velocity (m/s)
    HTC(average)