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在压力p=19.0～22.5 MPa,管内质量流速G=540～1 200 kg/(m2·s),内壁热流密度q=150～650 kW/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/pcr=0.96～0.98的区域内最易发生膜态沸腾(departure from nucleate boiling,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。
Under the conditions of the pressure p = 19.0-22.5 MPa, the mass flow rate in the pipe G = 540-1 200 kg / (m2 · s) and the inner wall heat flux q = 150-650 kW / m2, District heat transfer deterioration of a more systematic experimental study. Based on the experiments and the data from previous studies, a comparatively comprehensive comparison and analysis of the boiling heat transfer deterioration of water in the vertical rising light pipe and the female pipe in the critical pressure area are carried out. It is found that the departure from nucleate boiling (DNB) occurs most easily in the critical pressure zone (p / pcr = 0.96 ~ 0.98), ie, the critical dryness Minimum; with the pressure close to the critical pressure, the heat transfer characteristics of the female screw tube tends to deteriorate, and its ability to inhibit the DNB is reduced; the ability of the female screw tube to inhibit DNB mainly depends on the structural parameters of the female screw tube, Greater swirling thread construction helps to improve heat transfer.