摘要
超临界CO_(2)-Xe混合工质在新型超临界布雷顿循环发电系统中具有潜在应用前景,然而其传热行为并未受到广泛关注。该文通过数值方法探究超临界CO_(2)-Xe混合工质在内径8 mm垂直圆管内的换热特性,并讨论氙气(Xe)质量分数、热流密度和质量流速对传热的影响规律。根据超临界流体跨越类临界温度Tpc发生类相变的观点,将圆管内流体域划分为两层结构,即近壁类气膜和核心类液区,两层结构过渡于Tpc。基于类气膜和类液区引起的传热阻力及二者对传热影响的相对重要性阐述CO_(2)-Xe混合工质传热机理。结果表明:类气膜的热阻显著高于类液相,是控制对流换热系数及传热恶化发生的决定性因素;ω(Xe)越大,相同运行参数下CO_(2)-Xe混合工质热阻越大,换热能力越差。研究结果对超临界CO_(2)-Xe混合工质换热器设计具有一定指导意义。
Supercritical CO_(2)-Xe mixture has a potentialapplication prospect in the innovative supercritical Braytoncycle system. In contrast to supercritical CO_(2), heat transfercapability of supercritical CO_(2)-Xe mixture has not been widelyconcerned. The characteristics of supercritical CO_(2)-Xe mixtureflow and heat transfer in a vertical circular tube with an internaldiameter of 8 mm are explored through numerical method.Then, the effects of Xe mass fraction ω(Xe), heat flux, and massflux on the heat transfer of the mixture are discussed. Based onthe perspective of pseudo-phase transition during supercriticalfluid crossing pseudo-critical temperature, the fluid domainwithin the circular tube is divided into a two-layer structure: avapor-like film near the tube wall and a liquid-like region in thecore, with a transition occurring at the pseudo-criticaltemperature Tpc. The heat transfer mechanism is illustratedbased on the heat transfer resistance caused by vapor-like filmregion and liquid-like region, and the relative importance of theabove factors on the heat transfer. It is found that the heattransfer resistance of vapor-like film, which is significantlyhigher than that of the liquid-like, is the key factor controllingthe convective heat transfer coefficient and occurrence of heattransfer deterioration. Furthermore, the larger the ω(Xe) is, thehigher the heat transfer resistance of the CO_(2)-Xe mixture at thesame operating parameters, so that the heat transfer capabilityis worse. The research result is of significance to the design ofheat transfer equipment for supercritical CO_(2)-Xe mixture.transfer equipment for supercritical CO_(2)-Xe mixture.
作者
武文华
张鑫奕
闫晨帅
赵亚莹
张炎
吴熙
WU Wenhua;ZHANG Xinyi;YAN Chenshuai;ZHAO Yaying;ZHANG Yan;WU Xi(School of Energy and Power Engineering,Northeast Electric Power University,Jilin 132012,Jilin Province,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2024年第22期8948-8956,I0021,共10页
PROCEEDINGS OF THE CHINESE SOCIETY FOR ELECTRICAL ENGINEERING
基金
国家自然科学基金项目(52206132)
吉林省教育厅科学研究项目(JJKH20230116KJ)
吉林省自然科学基金项目(20230101341JC)。
关键词
超临界传热
混合工质
类相变
传热阻力
数值模拟
supercritical heat transfer
mixture
pseudo-phase transition
heat transfer resistance
numerical simulation
