Behaviors of Micro-layer in Micro-channel Boiling System Applying Laser Extinction Method

摘要

To elucidate the mechanism and characteristics of boiling heat transfer in a micro-channel vaporizer, the experimental investigation of the micro-layer thickness that formed between the heating surface and vapor generated was important. The micro-layer thickness was measured applying the laser extinction method for channel gap sizes of 0.5, 0.3, and 0.15 mm. It was clarified that the gap size, the rate of bubble growth, and the distance from the incipient bubble site have an effect on the micro-layer thickness in a micro-channel boiling system. The initial micro-layer thickness grew with an increase of the velocity of bubble forefront to moderate the value of the velocity. In the region of greater velocity, the thickness was constant for each gap. The distributions of the initial thickness of micro-layer on the heat transfer surface were shown.