近临界及超临界压力区垂直光管和内螺纹管传热特性的试验研究

阐述了眚上升布置的内螺纹管和光管在近临界及超临界压力区的传热牧场 生的试验结果。在近临界压力区。随着压力向临界压力造近，光管的传热特性变差，传热恶化的临界干度下降得很厉害，甚至在过冷区就会发生壁温飞升；内螺纹管在近临界压力区可以消除传热恶化，但是随着靠近临界压力其抑制传热恶化的能力下降。传热恶化后的光管和内螺纹管的最小传热系数分别在压力为21．0MPa和22．0MPa。超过临界压力后，光管和内螺纹管的传热特性得到改善，内螺纹管在高焓值区可以降低壁温。

Experimental Investigation of Heat Transfer Characteristics of Vertical Smooth Tubes and Internally Ribbed Ones in Near-critical and Supercritical Pressure Zones

Presented in this paper are the test results of the heat transfer characteristics of vertical smooth tubes and internally ribbed ones in near critical and supercritical pressure zones. In the near critical pressure zone the heat transfer characteristics of the smooth tubes will deteriorate when the pressure increases to approach the critical pressure. The critical dryness of heat transfer deterioration will experience a drastic reduction. In extreme cases there emerges a dramatic rise in wall temperature even in a sub cooled zone. As for an internally ribbed tube, its heat transfer deterioration in the near critical pressure zone can be eliminated. However, with the pressure approaching a critical one the capacity of the internally ribbed tube to suppress heat transfer deterioration will decrease. The minimum heat transfer factor of the smooth tube and internally ribbed tube after a heat transfer deterioration will occur respectively at a pressure of 21.0 MPa and 22.0 MPa. After surpassing the critical pressure the smooth tube and the internally ribbed one will have their respective heat transfer characteristics improved. In a high enthalpy zone the internally ribbed tube can experience a reduction in wall temperature.