脉冲加热下微尺度表面流动沸腾

利用微机电系统(MEMS)加工技术，在梯形微通道内集成特定形状(60 μm×100 μm)的Pt微加热器，通过改变脉冲加热电压及水的流速，采用高速摄像机观察并记录微加热器表面的流动沸腾现象，根据脉冲宽度2 ms下不同流速及热流时微加热器表面的核态沸腾及膜态沸腾现象得到了沸腾流型图.结果表明：在一定流速条件下，随着微加热器的热流增加，核态沸腾及膜态沸腾相继出现在微加热器表面，且核态沸腾开始向膜态沸腾转变；同时，增加水的流速，可使微加热器上发生核态沸腾及膜态沸腾所需的热流量增大.

Flow Boiling on a Microscale Surface under Pulse Heating

Using MEMS technology, a Pt microheater (60 μm×100 μm) fabricated on a glass wafer was placed in a silicon based microchannel of trapezoidal cross section. With the aid of a high speed CCD, flow boiling phenomena on the surface of the microheater in the microchannel under pulse heating were observed and recorded. At a given mass flux, nucleate boiling and film boiling began to appear on the microheater with increasing heat flux. A flow boiling map, showing the effects of heat and mass flux on the nucleate and film boiling regimes on the microheater at a pulse heating width of 2 ms, was presented. It is found that the nucleate boiling was changed to film boiling as the heat flux supplied by the microheater is increased. Furthermore, increasing mass flux increases the heat flux required for the incipience of nucleate boiling and film boiling on the microheater in the microchannel.