Abstract
Boiling heat transfer experiments were performed by using ethanol as test fluid. A heat transfer surface was at the bottom wall of the flow channel. Two types of experiments were conducted; horizontal-rectangular-narrow flow channel experiments and horizontal-narrow-flat space experiments. Experiments were conducted at the pool condition and at 0.1 MPa. In the rectangular-narrow flow channel experiments, a large bubble periodically left from the heat transfer surface and moved to the both ends of the flow channel. In the experiments of the narrow-flat space experiments, when the space was wide, bubbles generated on the heat transfer surface left freely from the flat space. The heat transfer characteristics were close to those of coalesced bubble in narrow channel, h=Cq^<0.12>. The critical heat flux decreased with a decrease in the flow channel height. When the flow channel height was large, the critical heat flux was close to the pool boiling value. The dependency of the CHF on the flow channel height was similar to that of natural convection boiling in a vertical-narrow-rectangular channel.
