Fig. 2 shows a schematic diagram of the vertical test section,
which is a /25 3 mm smooth tube with a heated length of 2 m.
The tube material is 1Cr18Ni9Ti. The thermal insulator is placed
on the outer tube wall to minimize heat loss. The temperature of
the outside wall is measured using /0.2 mm NiCr–NiSi K-type
thermocouples, which are attached on the outer tube wall. The
thermocouple arrangement on the test section is also shown in
Fig. 2. The /3 mm NiCr–NiSi-armored thermocouples are inserted
into the tube to measure fluid temperature. Pressure drop over
the test section and inlet pressure are measured using a pressure
transducer and a differential pressure transducer, respectively.
Heat flux is estimated from the input electric power and heat loss.