.TAeZoSysPro.HeatTransfer.Functions.ForcedConvection.internal_pipe_ASHRAE

Information

The following Dittus and Boelter (1930) correlation is applicable for a fully turbulent internal flows in pipes.
The formula is picked from the ASHRAE guide chapter 3 table 9 equation T9.5 and 9.6

The correlation is given for a Reynolds number Re > 10⁴.

The value of the exponent over the Prandtl number depends on whether the pipe wall is warmer or colder than the fluid. If the pipe is warmer (heating mode), n = 4 and n = 3 (cooling mode) otherwise.

Where :

• Nu is the Nusselt number
• Re is the Reynolds number
• Pr is the Prandtl number
• DeltaT is the temperature difference between the wall and the fluid

Interface

function internal_pipe_ASHRAE
  extends Modelica.Icons.Function;
  input Modelica.SIunits.PrandtlNumber Pr;
  input Modelica.SIunits.ReynoldsNumber Re;
  input Modelica.SIunits.TemperatureDifference dT;
  output Modelica.SIunits.NusseltNumber Nu;
end internal_pipe_ASHRAE;