functionconvectionResistance
Thermal resistance between the fluid and the tube
Information
This model computes the convection resistance in the pipes of a borehole segment with heigth hSeg.
The correlation of Dittus-Boelter (1930) is used to find the convection heat transfer coefficient as
Nu = 0.023 Re0.8 Prn,
where Nu is the Nusselt number, Re is the Reynolds number and Pr is the Prandlt number. We selected n=0.35, as the reference uses n=0.4 for heating and n=0.3 for cooling. Dittus-Boelter's correlation is valid for turbulent flow in cylindrical smooth pipe.
+References
Dittus P.W. and L.M.K Boelter, (1930). Heat transfer in automobile radiators of the tubular type. Univ Calif Pub Eng, 2(13):443-461. (Reprinted in Int. J. Comm. Heat Mass Transf. 12 (1985), 3:22). DOI:10.1016/0735-1933(85)90003-X.
Inputs
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.Height | hSeg | Height of the element | |
| Modelica.Units.SI.Radius | rTub | Tube radius | |
| Modelica.Units.SI.ThermalConductivity | kMed | Thermal conductivity of the fluid | |
| Modelica.Units.SI.DynamicViscosity | mueMed | Dynamic viscosity of the fluid | |
| Modelica.Units.SI.SpecificHeatCapacity | cpMed | Specific heat capacity of the fluid | |
| Modelica.Units.SI.MassFlowRate | m_flow | Mass flow rate | |
| Modelica.Units.SI.MassFlowRate | m_flow_nominal | Nominal mass flow rate |
Outputs
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.ThermalResistance | R | Thermal resistance between the fluid and the tube |
Revisions
-
February 14, 2014, by Michael Wetter:
Removed unused inputrBor. Revised documentation. -
January 24, 2014, by Michael Wetter:
Revised implementation. ChangedcpFluidtocpMedto use consistent notation. Added regularization for computation of convective heat transfer coefficient to avoid an event and a non-differentiability. -
January 23, 2014, by Damien Picard:
First implementation.