Abstract
This study evaluated boiling heat transfer in a quasi-two dimensional space by visualizing both flow structure near a heat transfer surface using particle image velocimetry and liquid film beneath bubbles using back light method, simultaneously. In isolated bubble region at low heat flux, a single bubble pushed aside superheated liquid near a heat transfer surface and a rising bubble formed a wake and a vortex to enhanced convection on the surface. In coalesced bubble region at high heat flux, the evaporation of liquid film took place mainly while detaching coalesced bubbles induced relatively fast downward flow occasionally. Estimated liquid film thickness decreases as heat flux increases in agreement with earlier studies.
