非均匀加热立式螺旋管内沸腾传热恶化特性研究

本文主要开展非均匀加热螺旋管内沸腾传热恶化特性实验研究。实验参数范围为:热流密度15~55 kW·m^-2;质量流速190~400 kg·m^-2·s^-1;压力0.8~1.1 MPa。实验包括一个均匀加热实验段及两个非均匀加热实验段,三个实验段尺寸一致,不均匀度分别为1.0,1.2和1.4。实验过程中共获得三种壁温飞升现象,而且发现随着质量流速及不均匀度的增大传热恶化位置逐渐向内侧管圈偏移,并由此导致非均匀加热螺旋管内初始烧干干度随着质量流速的变化规律与均匀加热螺旋管恰好相反。

Dry-out Characteristics of Boiling Flow in the Circumferentially Non-uniformly Heated Helically Coiled Tubes

The dry-out characteristics of boiling flow in the circumferentially non-uniformly heated helically coiled tubes are studied.The experimental parameters are as follows:the heat flux is 15~55 kW·m^-2,the mass flux is 190~400 kg·m^-2·s^-1,the pressure is 0.8~1.1 MPa.The experiments were performed with one uniformly heated tube and two non-uniformly heated tubes.Three helically coiled tubes have the same size and the rations between the maximum and the average heat flux are 1.0,1.2 and 1.4 respectively.Three differernt kinds of temperature distribution are obtained in present study.The initial dryout position gradually shift to the inner side of the tube with increase of the qmax/qavg and mass flux,and thus cause the initial dry-out quality changes with the mass flux in the non-uniformly heated tubes just opposite to that in the uniform heating tube.