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实验研究了脉冲加热条件下PDMS玻璃微槽(300μm×60μm)内FC-72液体的流动沸腾现象,通过研究单个气泡的核化,生长和塌陷来了解微槽内脉冲加热沸腾的机理.核态沸腾发生在加热开始后的一段时间,根据实验条件的不同,沸腾起始的过热度从84.9℃到91.2℃变化,在脉冲加热结束以后液体蒸发仍在继续直到加热片温度降低到92.0℃左右.由于微槽的高宽比非常小,快速生长的气泡迅速覆盖整个微加热片并向上下游扩展导致了加热片的传热恶化.当长气泡被往下游推离加热片上方区域后,一个连接长气泡的薄蒸汽膜将覆盖在加热片上,同时换热效果比气泡覆盖加热片时大幅增加.
The flow boiling phenomenon of FC-72 liquid in PDMS glass micro-groove (300μm × 60μm) under pulsed heating was studied experimentally, and the mechanism of pulsed heating and boiling in microchannels was studied by studying the nucleation, growth and collapse of single bubble. Boiling occurred some time after the start of heating. According to the different experimental conditions, the degree of superheat at the start of boiling changed from 84.9 ℃ to 91.2 ℃. After the end of pulse heating, the liquid evaporation continued until the temperature of the heating plate decreased to 92.0 ℃. Due to the very low aspect ratio of the microgrooves, rapidly growing bubbles quickly cover the entire microtrope and propagate upstream and downstream, leading to a deterioration of the heat transfer of the fin. As long bubbles are pushed downstream from the area above the fins, a connection A long bubble of thin vapor film will cover the heating plate, while the heat exchange effect than the bubble covered heater significantly increased.