高热流密度下R113核态沸腾中汽化核心密度的识别

1引言核态沸腾是一种被工业界广泛应用的传热技术,在冶金、化工、动力等领域有广泛的发展前景。其优点是能以较低的温差传递较多的热量。在核态沸腾中有相变发生,相变发生的地方是成核地点1],称为汽化核心。汽化核心的研究对于核态沸腾技术的发展具有非常重要的意义。传统的拍

Identification of Densities at the Nucleation Sites in a R113 Nucleate Boiling under a High Heat-flux Density

A R113 nucleate boiling experiment was conducted on a transparent ITO glass.During the experiment a high speed CCD(Charge Coupled Device) camera was placed under the ITO glass to take photos of the bubble images.The advantage of such a camera shooting consists in the elimination of the interference to the camera shooting caused by the merging of the fluid and bubbles.By the use of an image edge detection technique these bubble images were processed so that one can clearly see the boundaries of various bubbles in the bubble cluster,thus making it possible to correctly identify the quantity of bubbles.By taking account of the difference between the quantity of bubbles due to their merging and the quantity of nucleation sites under the bubbles,the actual magnitude of nucleation site quantity can be determined.Finally,a curve showing the variation of densities of the nucleation sites with heat-flux densities was plotted.