中文摘要：

摘要本文在压力P=19．0～22．5MPa、质量流速G=600～1000kg／（㎡s）、内壁热流密度q=300～500kW／㎡的参数范围内，对水在新型垂直上升内螺纹管内的传热特性进行了实验研究。研究发现，在近临界压力区，内螺纹管的内壁温随质量流速的增加而降低，随热流密度的增大而升高。在本文研究参数范围内，近临界压力区的水在内螺纹管内传热时并未出现明显的传热恶化。通过实验数据的对比发现，近临界压力区的亚临界压力部分水的传热特性与超临界压力部分水的传热特性具有相似性。

英文摘要：

The heat transfer of water in vertically upward new type internally ribbed tubes was investigated experimentally. The experimental parameters are as follows. The pressure at the inlet of the test section ranged from 19.0 to 22.5 MPa, the mass velocity of the fluid was from 600 to 1 000 kg/（㎡s）, and the heat flux on the internal wall of the tube was varied from 300 to 500 kW/㎡. It was shown that in near critical pressure region, with the increase of mass velocity, the internal wall temperature of the internally ribbed tube decrease, while with the increase of heat flux, the internal wall temperature increase. Within the parameter range in this paper, there was no significant heat transfer deterioration to water in near critical pressure region in internally ribbed tubes. According to experimental data, the heat transfer characteristic of subcritical water in near critical pressure region was considered to be similar to that of supercritical water in near critical pressure region.