摘要
在低质量流率条件下,对垂直上升内螺纹管在亚临界和近临界压力区的传热特性进行了实验研究。实验参数范围为压力p=12-22.5 MPa,质量流率G=170-420 kg/（m^2·s）,内壁热负荷q=150-366 k W/m^2。实验结果表明：在亚临界压力区,垂直上升内螺纹管发生了第二类传热恶化,即干涸（dryout）。内壁热负荷和压力的增大,均会导致干涸点的提前以及干涸后内壁温度的峰值增大。质量流率对干涸点的影响呈现非单调性,存在一界限质量流率。当质量流率小于界限质量流率时,干涸点随质量流率的增加而提前;当质量流率大于界限质量流率时,干涸点随质量流率的增加而推迟。在近临界压力区的亚临界压力部分,内壁热负荷较高时容易发生第一类传热恶化,即膜态沸腾（DNB）。内壁热负荷的增大和质量流率的减小,均会导致传热恶化的提前以及膜态沸腾后的温度飞升值增加。在近临界压力区的超临界压力部分,内螺纹管传热良好,在拟临界区域出现一定程度的传热强化,其传热特性和亚临界压力区的传热特性相似。
Within the range of pressure from 12 to 22.5 MPa, mass flux from 170 to 420 kg/（m^2·s） and inner heat flux from 150 to 366 k W/m^2, an experiment was conducted to investigate on the heat transfer characteristics of vertical upward internally ribbed tube. The experimental results show that dryout occurs at subcritical pressure. With the increase of inner wall heat flux and pressure, dryout occurs ahead and the peak wall temperature after dryout goes up. The effect of mass flux is non-monotonic and there exists a critical mass flux. When mass flux goes up, dryout appears ahead if it is lower than the critical mass flux and is delayed if it is above the critical mass flux. At subcritical pressure in near critical pressure region, departure from nucleate boiling（DNB） occurs at high heat flux. The increase of inner wall heat flux and the decrease of mass flux can delay the DNB and lead to higher peak wall temperature after heat transfer deterioration. At supercritical pressure in near critical pressure region, the heat transfer performs well and the heat transfer is enhanced in the pseudo-critical enthalpy region. The heat transfer characteristic is similar to that in subcritical pressure region.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2015年第8期1947-1953,共7页
Proceedings of the CSEE
基金
中国科学院战略性先导科技专项项目(XDA07030100)~~
关键词
低质量流率
亚临界及近临界压力
内螺纹管
传热特性
干涸
膜态沸腾
环形炉膛锅炉
low mass flux
subcritical and near critical pressure
internally ribbed tube
heat transfer characteristic
dryout
departure from nucleate boiling
annular furnace boiler
