A schematic diagram of the experimental apparatus is given in Fig.1, which is adopted to study the boiling two-phase flow in tube-bundle channels. In the experiments, all measured

data are recorded at the intervals of 10ms. The error in the pressure drop measurement is less than ±2%. The error in flow rate measurement is less than ±3%, and for temperature measurement is less than ±1%.

The test section of tube-bundle channel is composed of four straight electrical heaters and a thimble, which is shown in Fig. 2. The thimble is made of PMMA pipe for the purpose of flow visualization, of which the inner diameter is 35mm and the length is 2100mm. The dimension of the electrical heater is Ф8шш and 1500mm long; the gap between electrical heaters is 5mm; the width between electrical heater and thimble is 4.5mm. There are, along flow direction, three pressure sensors and five thermocouples. The length between pressure sensors is 200mm and that between thermocouples is 100mm.

Plexiglas pipe

Electric heat tube P3

P2

P1

Thermocouples

Fig. 2. Structure of test section

A schematic diagram of sub-channels partition is shown in Fig. 3. There are 9 sub-channels in the present test section.