近临界条件下二氧化碳自然循环沸腾临界实验研究  

Experimental Study of Carbon Dioxide Boiling Crisis in Near-critical Natural Circulation

作　　者：曾成天 周源 黄彦平[2] 罗乔 田耕源 黄家坚 ZENG Chengtian;ZHOU Yuan;HUANG Yanping;LUO Qiao;TIAN Gengyuan;HUANG Jiajian(Key Laboratory of Radiation Physics and Technology,Ministry of Education,College of Physics,Sichuan University,Chengdu 610065,China;Nuclear Power Institute of China,Chengdu 610213,China)

机构地区：[1]四川大学物理学院辐射物理及技术教育部重点实验室,四川成都610065 [2]中国核动力研究设计院,四川成都610213

出　　处：《原子能科学技术》2025年第3期513-523,共11页Atomic Energy Science and Technology

基　　金：国家自然科学基金(U2241278);中国核动力研究设计院重点实验室开放基金。

摘　　要：亚临界侧近临界二氧化碳(CO_(2))由于其饱和气相密度高、潜热低和表面张力极低等物性特点而表现出独特的沸腾传热行为。本文针对近临界条件下二氧化碳开展自然循环沸腾临界传热实验,实验结果表明:在6.8~7.2 MPa的近临界条件下,过冷沸腾条件下增加极小的热流密度(增加量仅0.6 kW/m2),出口侧的壁面温度迅速上升,并且壁面温度飞升不断向进口侧轴向传播。结合主流体处于过冷状态及临界热流密度随着流量增加而增加的特点,判断沸腾临界为偏离泡核沸腾(DNB)式沸腾临界。不同边界条件下沸腾临界实验发现,压力和进口过冷度的变化对临界热流密度影响较大。基于近临界物性畸变及DNB式沸腾临界的特性建立了一个理论假说,解释了流固耦合条件下独特气泡行为导致的传热恶化轴向自蔓延现象。Carbon dioxide is utilized as a direct coolant in micro-modular gas-cooled fast reactor cycle systems.The supercritical carbon dioxide cycle systems are attracted widespread attention for their compact design and high operating efficiency.In the case of a LOCA(loss of coolant accident)in carbon dioxide micro-modular gas-cooled fast reactors,the core pressure drops rapidly to a near-critical region.Near-critical carbon dioxide exhibits unique boiling heat transfer behavior due to its high saturation vapor density,low latent heat,and extremely low surface tension.The study of near-critical carbon dioxide heat transfer characteristics under conditions of physical distortion is critical to the design and evaluation of micro-modular gas-cooled fast reactor cycle systems.Experimental studies conducted in a closed loop under natural circulation and close to critical conditions.The boiling heat transfer characteristics of near-critical carbon dioxide was investigated.A typical experiment shows that under near-critical conditions ranging from 6.8 MPa to 7.2 MPa,the entire test section initially exhibites stable subcooled boiling.With a minimal power increase(0.6 kW/m2),the wall temperature at the outlet rises sharply and propagates upstream toward the inlet.The entire axial wall temperature rising phenomenon lasts approximately 800 s.During this period,inlet and outlet pressures,pressure differentials,and inlet temperature remain nearly constant,with a small increase in mass flux accompanying the increase in power.Enthalpy analysis indicate that subcooled boiling predominates throughout the axial bulk fluid.The low gas quality of the axial bulk fluid suggests a preliminary assessment of the departure from nucleate boiling(DNB).Subsequent analysis comprehensively examines the evolution of axial heat transfer deterioration under conditions of distorted properties and DNB-type boiling crises.The study highlights significant influences of pressure and inlet subcooling on the critical heat flux,with minimal effects observe fro

关 键 词：近临界 二氧化碳 沸腾临界 偏离泡核沸腾 

分 类 号：TL334[核科学技术—核技术及应用] TK124[动力工程及工程热物理—工程热物理]