A set of 14 K-type thermocouples was embedded in the copper
block. For each side of the test section presented in Fig. 2, there
were seven thermocouples inserted at equal distances of 16 mm
along the channel length and 4.3 mm along the direction perpendicular
to the channel length. These temperature measurements
were done to determine surface temperatures at six positions
using linear extrapolation. The arithmetic mean of these surface
temperatures was used to calculate the average heat transfer coef-
ficient. In addition, T-type thermocouples were installed at the inlet
and outlet of the test section to measure the fluid temperature.
All thermocouples and relevant instruments installed in the experimental
apparatus were well calibrated