Forced convection heat transfer in narrow annulus with bilateral heating

Experiments were conducted to study the single-phase forced convection heat transfer with water in vertical narrow annulus which is simultaneously heated from inside and outside by primary water. A comparative analysis on heat transfer performance between bilateral and unilateral heating was carried out. The results indicate that double side heating enhances the heat transfer on inside surface when Reynolds number is higher and reduces the heat transfer on outside surface when Reynolds number is small, compared with single-side heating. For both heating modes, the varying trend of Nusselt number is similar and the total heat transfer rate keeps almost equal in value.