Visualization of Pool Boiling From Plain and Enhanced Structures

A visualization study of pool boiling at atmospheric pressure from plain and enhanced structures was conducted with PF 5060 as working fluid. The single layer enhanced structures were fabricated in copper and were 1 mm thick. The parameters investigated in the present study are heat flux, width of microchannels and overall structure width. A monochrome CCD camera with attached magnifying lens served as the main tool for observation of the boiling process from the structures. The nucleate boiling regime for a plain surface is usually divided into two sub-regimes: the isolated bubbles regime and the coalesced bubbles regime. For enhanced structures, the increase in geometric complexity leads to different flow regimes that may establish under different heat fluxes. This study evaluates these regimes using movies and still photographs. A comparison with the plain case is made and the differences highlighted.