中文摘要：

在压力p=19.0-22．5MPa，管内质量流速（7=540-1200kg／（m2·s），内壁热流密度q=150-650kW／m2的参数范围内，对垂直上升管内水在临界压力区的传热恶化进行了比较系统的试验研究。在试验的基础上，结合前人研究数据，对临界压力区内，水在垂直上升光管和内螺纹管内的沸腾传热恶化进行了比较全面的对比、分析。研究发现，不论是光管还是内螺纹管，在临界压力区p／p。r=0．96-0．98的区域内最易发生膜态沸腾（departurefromnucleateboiling，DNB），即发生传热恶化的临界干度最小；随着压力接近临界压力，内螺纹管的传热特性有变坏的趋势，其抑制DNB的能力有所降低：内螺纹管抑制DNB的能力主要取决于内螺纹管的结构参数，采用具有更大旋流作用的螺纹结构，有助于改善其传热性能。

英文摘要：

The heat transfer deterioration of water in near critical pressure region in vertically upward tubes was investigated experimentally. The pressure at the inlet of the test section ranged from 19.0 to 22.5 MPa, the mass flux of the fluid was from 540 to 1 200 kg/（m2-s）, and the heat flux on the inside wall of the tube was varied from 150 to 650 kW/m2. According to the experimental data, a systematic analysis and comparison was made on the heat transfer deterioration in the near critical pressure region inside the vertically upward internally ribbed tubes and the smooth tubes. It is suggested that the critical steam quality of the heat transfer deterioration is the smallest at the ratio p/pcr=0.96-0.98 whether in the internally ribbed tubes or in the smooth tubes. With the pressure close to the critical pressure of water, the capacity of the internally ribbed tube for enhancing heat transfer and inhibiting DNB decrease. The capacity of the internally ribbed tube for inhibiting DNB mainly depends on the structure parameters of the internally-ribbed tube.