Visualization of Flow Boiling Regimes During Transfer Line Chilldown Process

The present work reports the flow visualization results for the transfer line chilldown process using a simulant fluid PF-5060 which has a boiling point of 56°C at ambient pressure. The visualization experiments are performed in a pyrex tube of outer diameter 15.875 mm and a thickness of 2.4 mm in a horizontal configuration. To mimic the cryogenic chilldown process, the outer walls of the tubes are preheated to around 210°C by wrapping Nichrome wire across the outer surface of the tube and heating up the wire by resistance heating method. The complex flow boiling regimes during the chilldown process such as the film, transition and nucleate boiling regimes were captured by the high speed imaging. Further, the heat transfer and high speed images are correlated to reveal the stratification effect in horizontal chilldown process. Overall, the flow visualization experiments revealed important transient flow boiling features during the chilldown process and will aid in future validation of predictive models