介電液FC-72混合可溶解氣體在狹窄矩形空間的池沸騰研究

Abstract

本論文是以介電液FC-72為工作流體且溶入溶解性氣體，在一大氣壓下，探討在狹窄矩形空間的池沸騰特性。在狹窄矩形空間下方為面積10mm×10mm的水平光滑銅片加熱面，上方為壓克力板，兩端以壓克力板檔住，可調整上下板的間隙距離S，間隙分為S=0.5mm、1mm、2mm、3mm四種。所加入的溶解性氣體為純空氣，溶解率Cg為0與0.0029。實驗目的在比較間隙大小、不同可溶解氣體濃度情況下，對起始過熱度、核沸騰熱傳與臨界熱通量的變化，並相互比較。實驗結果顯示，間隙大小對於池沸騰有很大的影響，不論有無加入可溶解氣體，其臨界熱通量皆隨著間隙變大而增大。加入可溶解氣體 (Cg=0.0029)比未加入可溶解氣體(Cg=0)的熱傳係數高，且臨界熱通量都有明顯的提昇，但是對於溫度偏移現象沒有抑制作用。

The goal of this thesis is to study the characteristics of pool boiling of dielectric Fluid FC-72 with dissolved gas in a narrow rectangular space under one atmosphere. The narrow rectangular space consists of a heated surface made of a smooth copper plate with 10mm×10mm area and a parallel acrylic plate with two confined side edges. The gap spacing S between the heated surface and the parallel acrylic plate are S=3mm、S=2mm、S=1mm and S=0.5mm. The dissolve gas is pure air which is made up of nitrogen and oxygen. The dissolve rates Cg are 0 and 0.0029. The onset of boiling, nucleate heat transfer and critical heat transfer flux at different S and Cg were studied. The results showed the gap spacing laced great influence on critical heat transfer flux. Which could be increased with gap size increasing matter the air dissolved in FC-72 or not. The heat transfer coefficients of the case with Cg=0.0029 were much higher than those of the case with Cg=0, and the critical heat transfer flux would be increased as well.