Experimental study on combined natural and gas-injection enhanced circulation

Abstract

The paper summarises the experimental results obtained in the frame of a research concerning natural and gas-injection enhanced circulation. These phenomena, having an interest for cooling accelerator driven subcritical reactor core systems (ADSs), are addressed making use of a downscaled facility presently operating with water, as a coolant fluid, and air, as gas injected to obtain gas-lifting. Previously published data from the research addressed separately the phenomena of natural circulation and of gas-injection enhanced circulation, comparing the experimental data with RELAP5 code predictions. After a description of the experimental facility and a summary of the previous experimental results, the present work discusses data obtained in experiments in which buoyancy due to temperature differences and voiding generated by air injection are combined. Different air injection flow rates and heating powers are used in this purpose. The quantitative trends obtained in the experiments are analysed and discussed. The expected overwhelming effect of gas-injection enhanced circulation with respect to natural circulation is one of the outcomes of the experimental data in the investigated range of parameters.