Abstract
A flow channel with the cross-section of a half circle was grooved on the Plexiglas plate. The length and the diameter of the flow channel were 26mm and 0.5mm, respectively. A patch electrically-heated was located at the off-set location from the center between both ends of the flow channel; at 8.5mm from the one end and at 17mm from the other end. The heating length was 0.5mm. The flow channel was filled with distilled water and the heating patch was heated periodically. One coalescent bubble was formed and condensed to disappear synchronizing with the pulse-wise heating. While this bubble formation and condensation continued periodically, flow from the short side to the long side in the flow channel was maintained. The flow rate increased as the heating rate was increased. The flow velocity and the flow rate obtained in the present experiments were 0.2∿6.5mm/s and 0.03∿1.35(mm)^3/s, respectively. The velocity of the interface between the bubble and liquid during the condensation period was much faster than that during the evaporation period. During the condensation period, the velocity of the interface at the short side was faster than that at the long side. The equation of motion of liquid in the flow channel was solved to calculate the traveling of liquid in the flow channel. Predicted velocities qualitatively agreed well with the experimental results. By applying the duration times of evaporation and condensation obtained in the present experiments to the predicted velocities during the respective evaporation and condensation period, an average flow velocity during one cycle of heating was derived. The flow velocity so obtained qualitatively agreed well with the experimental results.
