Cryogenic chilldown process under low flow rates

Transient cryogenic chill down process in horizontal and inclined pipes

“…The non-dimensional parameter T Ã is defined as: et al [32] and Yuan et al [13] using liquid nitrogen. The measurement sections were located at 90 mm and 76.2 mm away from inlet of the test section, for the studies conducted by Jackson et al [32] and Yuan et al [13], respectively. In general, trend of wall temperature reaching the chill down state is similar for all studies.…”

“…He stated that the mass flow rate does not affect the chill down time very significantly. However the studies conducted by Chi [9], Krishnamurthy et al [11], Dresar [12], and Yuan et al [13] demonstrated that an increase in liquid mass flow resulted decrease in chill down time. The prediction of rewetting temperature is also important in applications such as lighter water reactor (LWR) after a loss of coolant accident.…”

“…The visual observations captured the transition from film boiling to nucleate boiling, and revealed rewetting front shape. Yuan et al [13] investigated chill down process of a horizontal tube using liquid nitrogen with mass flux varying from 3.6 kg m À2 s À1 to 23 kg m À2 s À1 . Correlating the visual observations with circumferential temperature gradients, he suggested that the liquid filament-wall interaction was the major contributor to the chilling of bottom wall of transfer line.…”

Effect of Gravity on Film Boiling Heat Transfer and Rewetting Temperature during Quenching

“…2 and proposed a modification of the mass flow rate term: for 2 kg/m 2 s < G < 400 kg/m 2 s, it could be written 1 + 0.1G 0.4 . Recently, numerous models have been developed with a local approach (Ben David et al 1999;Yuan et al 2007), based on the local vapor quality or void fraction.…”

“…As we know, no correlation exists for a tube quenching under microgravity. Some analytical studies have been performed (Yuan et al 2007), some correlations have been built but not for our configuration. Xu (1998) and AdhamKhodaparast et al (1995) observed a decrease in the rewetting temperature in 0 g during the quenching of an horizontal plate by a parallel flow.…”