These single-phase flow experiments were the first to be conducted
to check the validity of the experimental system. The energy
balance of the test section is illustrated in Fig. 4, indicating
the test section, which was well insulated. The single-phase Nusselt
numbers were also compared with the prediction methods of
Gnielinski [24] and Lee and Garimella [25], which were applied
for laminar developing flow. The comparisons presented in Fig. 5
indicate that the experimental results tended to agree fairly with
the predictions, corresponding to a uniform heat flux boundary
condition.
The following sections present the two-phase flow results,
including flow pattern and heat transfer.