Session: 08-05: Computational Fluid Dynamics (CFD) and Applications - V

Paper Number: 135038

135038 - Numerical Investigation on the Enhancement of Steam-Air Condensation Heat Transfer Outside Spiral Pipes 

Abstract: 

When loss of coolant accident (LOCA) or main steam line break accident (MSLB) occurs in the nuclear power plant, a large amount of high pressure and temperature steam will be released into the air space, in third generation nuclear power unit of HPR1000, a Passive Containment Heat Removal System (PCS) is utilized for extracting heat from containment during reactor accident scenarios. Because the non-condensable gas in the space generates additional thermal resistance, which will deteriorate heat transfer in the condensation wall, it's crucial to enhance the heat transfer capacity of steam condensation containing non-condensable gas, thereby improving the heat transfer efficiency of PCS. Considering that previous studies on heat transfer enhancement have primarily focused on inclined tubes, nodular tubes, or special surface treatments such as chrome plating. In this study, a Computational Fluid Dynamics (CFD) method, which can simulate the heat transfer and mass transfer characteristics near the condensation wall, was employed to numerical simulate the heat transfer characteristics of steam-air condensation outside a spiral tube. The effects of different tube diameters range from 12 mm to 38 mm, different heights vary from 0.1 m to 3 m, on heat transfer characteristics were analyzed. The results indicate that the heat transfer coefficient of the spiral tube is 1.6~1.8 times higher than that of vertical tube, and certain configuration of the spiral tube exhibit higher heat transfer coefficients compared to horizontal tubes, meanwhile, there also exists a more intensive suction effect compare to vertical tube. Furthermore, it is observed that after changing the heights and diameters of spiral tube, their effects on the condensation heat transfer characteristics is consistent with that of the vertical tube, the heat transfer coefficient will increase with the diameter decreases, moreover, it exhibits exceptional heat transfer enhancement characteristics when the height of spiral tube is small, then when the height increases, there is a corresponding increase in the rotation cycles, consequently, during this period, there will be a significant decrease in the heat transfer coefficient due to the superposition of an air layer beneath the tube, the heat transfer coefficient will increase as the tube height continues to rise, owing to the suction effect. In addition, the condensation heat transfer mechanism of a spiral tube bundle structure was analyzed for a 1m high spiral pipe, and the impact of different tube pitch and radial pitch on the condensation heat and mass transfer mechanism was investigated, leading to the identification of an optimal spiral tube bundle structure.

Presenting Author: Ruihan Jing Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment

Presenting Author Biography: My name is Ruihan Jing, a master student from Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment of Harbin Engineering University, majoring in reactor thermal hydraulics and related numerical simulation.

Authors:

Ruihan Jing Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment
Lu Zhang China Nuclear Power Engineering Co., Ltd.
Haozhi Bian Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment
Xinyi Shen Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment
Xu Zhang College of Nuclear Science and Technology, Harbin Engineering University
Shuhang Zhou Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment
Xiang Peng Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment