Visualization of microbubble dynamic behaviors in open rectangular microgrooves heat sinks under saturated boiling condition

Abstract

The development of the bubbles under saturated boiling condition was investigated by a high speed camera with shooting speed of 4301 frames per second and a macro lens with the combination of VERSION and MATLAB software. Oscillation of the triple-phase contact line caused by bubble-burst, geometrical characteristics of triple-phase contact line under different heat fluxes condition, effect of heat flux on the oscillation time of the triple-phase contact line, influence of heat flux on the bubble period, impact of the superheat on the bubble departure frequency, effect of heat flux on the equivalent diameter of bubble-burst and surface temperature distribution of the microgrooves heat sink were all discussed. Experimental results show that bubble-burst makes the triple-phase contact line oscillate periodically. Oscillation time of the triple-phase contact line first increases and then decreases with the increasing heat flux, and there exists a time peak; bubble period reduces as heat flux increases; equivalent diameter of bubble-burst increases with the increase of heat flux; under the condition of the same heat flux and depth of the microgroove, equivalent diameter increases as the width of the microgroove increases. The surface temperature distribution of the microgrooves heat sink under saturated boiling condition is fluctuant, and there exist wave crest and trough on the surface of the microgrooves heat sink, corresponding to the temperature of the liquid and top wall between adjacent microgrooves, respectively. With the increase of the heat flux, the mean surface temperature of the microgrooves heat sink increases. There exists a temperature peak in 3D temperature distribution of the nucleate site when bubble bursts.