Thermal-hydraulic characteristics of supercritical pressure CO2 in vertical tubes under cooling and heating conditions. (1st March 2019)

• Record Type: Journal Article
• Authors: Guo, Jiangfeng; Xiang, Mengru; Zhang, Haiyan; Huai, Xiulan; Cheng, Keyong; Cui, Xinying
• Is Part Of: Energy. Volume 170(2019)
• Page Start: 1067
• Page End: 1081
• Publication Date: 2019-03-01
• Subjects: Supercritical pressure CO2 (SCO2) -- Buoyancy effect -- Heat transfer deterioration -- Heat exchanger -- Heat transfer -- Pressure drop; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2018.12.177
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: The thermal-hydraulic properties of supercritical pressure CO2 (SCO2 ) in vertical tubes under cooling and heating conditions were numerically investigated by using SST turbulent model with variable turbulent Prandtl number model. Under cooling condition, the peak of heat transfer coefficient appears near the pseudo-critical point, the buoyancy effect enhances local heat transfer for upward flow while deteriorates that for downward flow, and the criterion G r ¯ / R e 27 is more accurate than Bo ∗ in the evaluation of buoyancy effect. Under heating condition, the buoyancy effect improves local heat transfer for downward flow while deteriorates that for upward flow. The local heat transfer deterioration only occurs in the case of T b, in < T pc for upward flow, and the increasing T b, in may alleviate the local heat transfer deterioration. The decreasing heat flux and tube diameter could reduce or even eliminate the local heat transfer deterioration for upward flow. The present work may provide a practical guidance on mechanism acknowledge of thermal-hydraulic properties of SCO2 and optimization design of heat exchanger. Highlights: Buoyancy effect is advantageous to upward flow under cooling condition. Buoyancy effect enhances heat transfer for downward flow under heating condition. G r ¯ / Re 2.7 has better performance than Bo ∗ in description of buoyancy effect. The heat transfer mechanism can be attributed to the distributions of properties.