Experimental Study on Subcooled Pool Boiling in Microgravity Utilizing

<br /><div class="s1listtd6r" style="width: 700px; float: left; min-height: 18px; height: auto; display: table; padding: 3px 1px; font-family: Simsun">A temperature-controlled <span style="color: red">pool</span><span style="color: red">boiling</span> (TCPB) device was developed to perform <span style="color: red">pool</span><span style="color: red">boiling</span> heat transfer studies at both normal gravity and <span style="color: red">microgravity</span>. A platinum wire of 60 μm <span style="color: red">in</span> diameter and 30 mm <span style="color: red">in</span> length was simultaneously used as heaters and thermometers. The heater resistance, and thus the heater temperature, was kept constant by a feedback circuit. The fluid was R113 at 0.1 Mpa and <span style="color: red">subcooled</span> by 24 nominally for all cases. The results of the experiments at both normal gravity and <span style="color: red">microgravity</span><span style="color: red">in</span> the Drop Tower Beijing were presented. Nucleate and two-mode transition <span style="color: red">boiling</span> were observed. For nucleate <span style="color: red">boiling</span>, the heat transfer was slightly enhanced, namely no more than 10% increase of the heat flux was obtained <span style="color: red">in</span><span style="color: red">microgravity</span>, while the bubble pattern is dramatically altered by the variation of the acceleration. For two-mode transition <span style="color: red">boiling</span>, about 20% decrease of the heat flux was obtained, although the part of film <span style="color: red">boiling</span> was receded <span style="color: red">in</span><span style="color: red">microgravity</span>. A scale analysis <span style="color: red">on</span> the Marangoni convection surrounding bubble <span style="color: red">in</span> the process of <span style="color: red">subcooled</span> nucleate <span style="color: red">pool</span><span style="color: red">boiling</span> was also presented. The characteristic velocity of the lateral motion and its observability were obtained approximately. The predictions consist with the<span style="color: red">experimental</span> observations.</div>