Experimental investigation of non-condensable gas effects in a natural circulation system

Condensation heat transfer is a crucial aspect of designing passive containment cooling systems (PCCS) for nuclear reactors. Non-condensable gases (NCG) hamper this process, and their quantitative effect has been extensively studied. However, studies regarding wall temperature distribution during condensation are scarce. Therefore, to address this gap in the literature, this study focuses on analyzing the wall temperature distribution during the condensation of an air-steam mixture inside a vertical tube. Experimental measurements were performed with a variable amount of NCG and power output of the heater. The impact of NCG on steam condensation was quantitatively analyzed, with temperature distribution data with high spatial resolution obtained using two optical fiber sensors attached to the wall exterior. Experimental results from the test facility can be used to validate the computer code for nuclear accident analysis.