9 depicts the progression of local Darcy friction factor along the tube length, which is defined as:
9, the single phase and two-phase models give almost quite close results of local Darcy friction factor when the maximum change is around 2.
The evolution of local convective heat transfer coefficient gives very different results for the single and two-phase modeling however the results of Darcy friction factor are considerably similar which mean that the single-phase model still needs to be modified.
The Darcy friction factor
was calculated by Equation 3.
Darcy friction factor
is defined by the following equation:
For the straight duct tests the Darcy friction factor
was calculated by Equation 1; the plane locations are depicted in Figure 1.
The Darcy friction factor was calculated by Equation 1, where the plane locations are shown in Figure 2.
Darcy friction factors were calculated from test data for each test point and plotted on the Moody diagram.
Darcy friction factors
were calculated at each test point and plotted on Moody diagrams.