摘要
为探究超(超)临界锅炉机组内螺纹管水冷壁的传热特性,在倾角5°~90°的ϕ35 mm×7.75 mm倾斜上升内螺纹管中进行了实验研究,实验参数为压力15~28 MPa,质量流速600~1000 kg∙m^(-2)∙s^(-1),热通量300~500 kW∙m^(-2)。实验对比了内螺纹管与ϕ25 mm×3 mm光管的壁温特性;讨论了倾斜角度、质量流速和压力的变化对内螺纹管中亚临界、近临界和超临界水传热的影响;拟合了不同倾斜角度下超临界水的传热关联式。结果表明:所用内螺纹管有明显的推迟传热恶化、强化传热的性能;不同倾斜角度的内螺纹管传热特性存在差异;亚临界压力下质量流速对气液两相区传热系数影响很小,近临界和超临界压力下,随质量流速的增加,整体上传热系数增大;压力为15 MPa时的传热系数最大。超临界压力下,随压力的增大,大比热容区的传热系数减小。
To explore the heat transfer characteristics of rifled tube water wall in the supercritical(ultrasupercritical)boiler,an experiment was carried out in aϕ35 mm×7.75 mm upwards inclined rifled tube at different inclination angles from 5°to 90°.The experimental parameters are as follows:pressures from 15 to 28 MPa,mass flow rate from 600 to 1000 kg∙m^(-2)∙s^(-1),heat flux from 300 to 500 kW∙m^(-2).The wall temperature characteristics were compared between the rifled tube and theϕ25 mm×3 mm smooth tube.The effects of inclination angles,mass flow rate and pressures on the heat transfer characteristics of subcritical,near-critical and supercritical water in the rifled tube were discussed.The heat transfer correlations of supercritical water in the rifled tube at different inclination angles were developed.The results revealed that the rifled tube used in the experiment had the property of delaying heat transfer deterioration and enhancing heat transfer.The heat transfer characteristics of the rifled tube at different inclination angles were different.The mass flow rate had little influence on the heat transfer coefficients in the two-phase region at subcritical pressure.And with the increase of mass flow rate,the heat transfer coefficients increased at near-critical and supercritical pressure.The heat transfer coefficients at 15 MPa were higher than those at other pressures.Under supercritical pressure,as the pressure increases,the heat transfer coefficient of the large specific heat zone decreases.
作者
张鑫
刘朝晖
毕勤成
吕海财
杨冬
ZHANG Xin;LIU Zhaohui;BI Qincheng;LYU Haicai;YANG Dong(State Key Laboratory of Power Engineering Multiphase Flow,Xi’an Jiaotong University,Xi’an 710049,Shaanxi,China;College of Materials Science and Engineering,Shenzhen University,Shenzhen 518071,Guangdong,China)
出处
《化工学报》
EI
CAS
CSCD
北大核心
2021年第2期945-955,共11页
CIESC Journal
基金
国家重点研发计划项目(2018YFB0604403)。
关键词
内螺纹管
传热
倾斜角度
质量流速
压力
超临界水
两相流
rifled tube
heat transfer
inclination angles
mass flow rate
pressures
supercritical water
two-phase flow