非均匀受热条件下螺旋管内流动沸腾换热特性

目前对螺旋管在其管外表面均匀受热，管内两相流动换热的研究已十分丰富；但是在其管外表面非均匀受热条件下，管内两相流动沸腾换热特性的研究鲜有报道。为了解决螺旋管在实际运用中遇到的非均匀受热问题、得到其换热特性，本文采用了实验的方法研究了卧式螺旋管周向非均匀受热条件下管内流动沸腾换热特性。其中实验工况范围为系统压力P=0.7~1.0MPa，质量流速G=181~364kg/(m²·s)，质量干度χ=0.07~0.69。实验考察了螺旋管管外壁在两种非均匀受热条件下管内的两相流动沸腾换热系数与热流密度、质量流速、质量干度的关系，并与管周向均匀受热工况进行了比较。结果表明，在螺旋管外壁面“外半周绝热、内半周受热”情况下管内流动沸腾换热系数值最大，而管外壁面“内半周绝热、外半周受热”情况下最小。

Flow boiling heat transfer characteristics in helically coiled tube with circumferentially non-uniform heating

At present,researches on coiled tube,about internal flow and heat transfer characteristics,are only limited under the condition of uniformly heated,at the same time,non-uniform heating are rarely reported. But in practice,spiral tube is heated non-uniformly most of the time. To solve the problem,flow boiling heat transfer characteristics in horizontal helically coiled tube with circumferentially non-uniform heating,under the range of system pressure 0.7—1.0MPa,mass flux 181—364kg/(m²·s) and mass quality 0.07—0.69,were experimentally studied in this paper. The in-tube flow boiling heat transfer coefficient variations with surface heat flux,fluid mass flux,and mass quality were examined under two different non-uniform heating modes and also compared with the data of circumferentially uniform heating condition. Results showed that the in-tube flow boiling heat transfer coefficient was the highest under the condition of the inner half wall heated and outer half wall adiabatic,while it was the lowest with the inner wall heated and outer wall adiabatic.