Measurement of Condensation Heat Transfer Coefficient inside a Vertical Tube in the Presence of Noncondensable Gas.

Abstract Degradation of condensation HTC (Heat Transfer Coefficient) under an air presence in a vertical tube was explored both experimentally and analytically, with the aim of developing evaluation methods for the design of passive containment cooling systems in the next generation reactors. Measurements were done using a stainless steel tube of 49.5 mm I. D. and 2.0 m length, enclosed by a cooling jacket. Flow rates of steam, air and cooling water, and the system pressure were varied as the experimental parameters. First, condensation HTC was correlated to a function of mixture Reynolds number and air partial pressure ratio, in which thermal resistance of the condensate film was excluded. Secondly, an analogy between heat and mass transfer was applied. The calculated values agreed well with the measured values of condensation HTCs in turbulent flow, while an obvious underestimation was observed for the flow in which mixture Reynolds number was lower than 2.300. Finally, ratios of calculated to experimental HTCs. which include thermal resistances of the condensate film, averaged 1.01 for turbulent steam flow. KEYWORDS: nuclear power plantspassive containment cooling systemdegradationcondensationheat transfer coefficientvertical tubepassive safetypartial pressurenoncondensable gasanalogycorrelationsexperimental data