摘要
不凝性气体制约换热设备安全和系统效率,为研究不凝性气体-蒸气于水平管外自然对流凝结换热机理和特性,实验测量了不凝性气体He、N_(2)、CO_(2)质量分数分别为1.16%~18.18%、7.56%~60.86%、11.39%~70.95%,壁面过冷度为5~25 K,总压力为5~101 kPa的H_(2)O-He、H_(2)O-N_(2)、H_(2)O-CO_(2)自然对流条件下水平管外凝结换热特性,对比分析了H_(2)O-He、H_(2)O-N_(2)、H_(2)O-CO_(2)的不凝性气体质量含量、壁面过冷度以及压力因素的影响。压力和壁面过冷度一定,相同质量分数时,实验凝结传热系数与Nusselt理论解的比值(Q/Q_(Nu))由大到小依次为:H_(2)OCO_(2)、H_(2)O-N_(2)、H_(2)O-He;相同摩尔分数时,Q/Q_(Nu)由大到小依次为:H_(2)O-He、H_(2)O-N_(2)、H_(2)O-CO_(2)。相同总压力和不凝性气体质量分数时,H_(2)O-He的Q/Q_(Nu)随着壁面过冷度的增加下降最为缓慢。相同不凝性气体质量分数和壁面过冷度时,H_(2)O-He的Q/Q_(Nu)值最小,其受压力影响最为显著。
Noncondensable gas restricts the safety of heat exchange equipment and system efficiency.To study the mechanism and characteristics of free convective condensation of steam in the presence of noncondensable gas on horizontal tube,this paper experimentally studied steam condensation on horizontal tube in presence of noncondensable gas with mass fraction of He,N_(2) and CO_(2)changing of 1.16%—18.18%,7.56%—60.86%and 11.39%—70.95%,respectively.Horizontal tube surface wall subcooling ranged of 5—25 K.The total pressure varied with 5—101 kPa.The condensation characteristics Q/Q_(Nu) of H_(2)O-He,H_(2)O-N_(2),and H_(2)O-CO_(2)for different noncondensable gas mass fraction,surface subcoolings and pressures were analyzed and compared.When pressure and surface subcooling are constant,for the same mass fraction of noncondensable gas the order of Q/Q_(Nu) from large to small is H_(2)O-CO_(2),H_(2)O-N_(2),H_(2)O-He,but for the same mole fraction the order of from large to small is H_(2)O-He,H_(2)O-N_(2),H_(2)O-CO_(2).For the same total pressure and noncondensable gas mass fraction,Q/Q_(Nu) of H_(2)O-He decreased most slowly with the increase of surface subcooling.For the same noncondensable gas mass fraction and surface subcooling,the value of Q/Q_(Nu) of H_(2)O-He is the smallest,and it is most significantly affected by pressure.
作者
鲁军辉
李俊明
LU Junhui;LI Junming(School of Environment and Energy Engineering,Beijing University of Civil Engineering and Architecture.Beijing 100044,China;Key Laboratory for Thermal Science and Power Engineering of Ministry of Education,Department of Energy and Power Engineering,Tsinghua University,Beijing 100084,China)
出处
《化工学报》
EI
CSCD
北大核心
2022年第9期3870-3879,共10页
CIESC Journal
基金
国家重点研发计划项目(2016YFB0600105)
北京学者计划项目(2015 No.022)
北京市博士后工作经费资助项目(2021-ZZ-112)
北京建筑大学市属高校基本科研业务专项(X21016)。
