本文阐述在亚临界及近临界压力区,φ18×3不锈钢管内竖直下降汽水两相流沸腾传热特性的实验研究。实验参数为:压力 p=17.2—22.6 MPa,质量流速 G=800—2000kg/m~2·s,外壁热负荷q_0=220-460kW/m~2。实验结果表明,在亚临界及近临界压力区,竖直下降管内汽水两相流沸腾传热特性随压力提高得到改善;而在超临界压力下的传热特性比近临界压力区的差。 This paper describes the experimental study on the boiling heat transfer characteristics of two-phase flow of soda and water vertically in a φ18 × 3 stainless steel tube in subcritical and near-critical pressure zones. The experimental parameters are: pressure p = 17.2-22.6 MPa, mass flow rate G = 800-2000kg / m ~ 2 · s, outer wall thermal load q_0 = 220-460kW / m ~ 2. The experimental results show that in the subcritical and near-critical pressure zone, the boiling heat transfer characteristics of the two-phase flow in the vertical downcomer are improved with the increase of pressure, while the heat transfer characteristics at supercritical pressure are worse than the near-critical pressure zone.