Abstract
Flow boiling heat transfer in a vertical capillary tube, ID=1.45mm, is experimentally investigated using water for a sub-atmospheric and an atmospheric pressure condition in a range of mass flux from 20 to 100 kg/m^2s and a range of heat flux from 10 to 750 kW/m^2. The dominant flow pattern is found to be slug-annular and annular flow. It is found that heat transfer coefficient is not so dependent on heat flux, but dependent on quality. Therefore, heat transfer mechanism is primarily due to the convective boiling. The heat transfer coefficient is enhanced at a low heat flux and is underpredicted by Chen correlation. However, the correlation gives good prediction at a high heat flux.
