Experimental Investigation On A2-D Scaled IVR Heat Transfer Characteristics

The limiting factor for the In-Vessel Retention IVR is the Critical Heat Flux CHF,which terminate the External Reactor Vessel Cooling.The cooling mechanism is the combination of flow boiling and national convection forced convection.In This study,IVR heat transfer characteristics is investigated via two approaches.First,an experimental investigation on the flow nucleate boiling to assess the heat transfer coefficient in the ULPU-like facility under power of 9kW and the step up resistant corresponding power shape.The overall approach based on the measured temperatures of the flow channel,the metal temperature,loop flow rate and a high-speed camera records.Second,numerical simulation for the flow subcooled nucleate boiling by using ANSYS Fluent coupled with the wall boiling model,to examine the impact of geometry and orientation on vapor volume fraction.This was performed by running two models,one is a vertically oriented upward flow channel and the other is curved like the ULPU channel.The experiment results showed that the cooling mechanisms,convection and nucleation boiling are sufficient to maintain the heater surface temperature at constant level and the critical heat flux was not reached.The numerical simulation proved that the curved channel experienced relatively high vapor volume fractions along its curve length more than the vertically oriented channel.