In the porous media model, the heat transfer coefficient, [h.sub.fs], between the fluid and the solid in the energy conservation equation was specified by the empirical Dittus-Boelter equation
For laminar flow, the Nusselt number is Nu = 3.66, while for turbulent flow, the Nusselt number can be calculated by the Dittus-Boelter equation
For a single-phase flow, we use the Dittus-Boelter equation
for the heat transfer coefficient [[alpha].sub.In] in the pipe.
The CFD analysis of Nusselt number for pure water inside flat tube was compared with Dittus-Boelter equation
(9) for water inside circular tube was shown as black solid line.
Nus represents Nusselt number for smooth duct of a solar air heater and can be obtained by the Dittus-Boelter equation
Heat transfer coefficient is calculated from a Dittus-Boelter equation
(2002) for two-phase flow, enhanced tube Heat-transfer coefficient Dittus-Boelter equation
(Shah 1979) for single-phase flow Goto et al.