Critical heat flux in narrow tubes under uniform heating condition

The critical heat flux in narrow tubes with 1-3 mm inside diameter was investigated for the exit equilibrium qualities from subcooled to quality regions using water at ambient pressure. In the subcooled region, critical heat flux increased with the decrease of the tube inside diameter, and in the quality region, vice versa. Further, the critical heat flux for the 2 and 3 mm inside diameter tubes was confirmed to increase with the increase of qualities in the near zero quality region. This means the existence of a minimum in the critical heat flux in the region. These characteristics were explained qualitatively with the difference of the mechanisms of the critical heat flux between subcooled and quality regions. (author)