Experimental study of heat transfer coefficients in ITER vacuum vessel cooling channels

The paper describes the results of thermal-hydraulic tests with single rectangular vacuum vessel (VV) channel models performed to measure heat transfer coefficients under typical VV fluid conditions. The experiments have been carried out on the thermal-hydraulic facility developed at the Central Boiler and Turbine Institute (CBTI) for wide-range tests of power plant equipment. This facility comprises a water loop 30 m in height designed for the full-scale study of nuclear reactor passive cooling. The VV test element is a rectangular channel 0.2 m in width, 3 m in total length, 2.48 m in heated length. The channel height (δch) is variable, i.e. δch=12.5, 25 or 50 mm. The heat transfer coefficients have been obtained as a function of flow rate, channel height, model inclination and heating power