Flow Boiling of a Refrigerant HCFC123 in a Mini-tube

authorThis paper presents an experimental investigation on forced convective boiling of a refrigerant HCFC123 in a mini-tube. The inner diameters of the test tubes, D are 0.51mm and 0.30mm. First, two-phase frictional pressure drops were measured in adiabatic conditions, and compared with the correlations for conventional tubes. The frictional pressure drop data were lower than the correlation for conventional tubes. However, the data were in accord with those for conventional tubes qualitatively, and correlated in the form φ_L^2/X_<tt>. Next, heat transfer coefficients were measured in conditions of constant heat flux, and compared with those for conventional tubes. The heat transfer characteristics for min-tubes were different from those for conventional tubes, and so complicated. The heat transfer coefficients for D＝0.51mm increased with heat flux, but were almost independent of mass flux. Although the heat transfer coefficients were higher than those for a conventional tube (D＝10.3mm) in low quality region, they decreased with quality. The heat transfer coefficients for D＝0.30mm were higher than those for D＝0.51mm, and almost independent of both mass flux and heat flux