奈米流體在不同外型微流道中的對流熱傳實驗研究

Abstract

奈米流體為均勻穩定地懸浮有奈米粒子的懸浮液。對水和不同體積分率的二氧化鈦奈米流體、在不同雷諾數及在不同輸入功率的情況下，本文以實驗方法研究直和曲折流道內的熱對流。PDMS流道、加熱電極和測溫電極一併以微機電製程建構在矽晶圓基板上，本文發現傳入到流道中流體的功率在不同參數下並不相同(大約為數%至80%)，並發展出一方法以分析傳入流道和散逸至周圍功率的比例。實驗結果顯示對流熱傳係數隨雷諾數和體積分率的增加而上升，但奈米流體只較基礎流體略優，另曲折流道較直流道佳

Nanofluid is a liquid suspended uniformly and stably with nano particles. The convection heat transfer of TiO2-water nanofluid in straight and zigzag micro channels were studied for different particle volume fractions, different Reynolds number and different applied heating power. The channels were fabricated with PDMS on a silicon wafer with also both the heating and temperature sensing electrodes deposited on the substrate. It was found that a different amount of input power (from several % up to 80% ) can be delivered to the fluid (water or nanofluid) flow inside the channel, and a method was proposed for quantifying such a power fraction, with the rest lost into the surrounding. For the forced that convection inside the channel, we found that the heat transfer coefficient increased as the Reynolds number increases (a feature for all the fluid), and as the volume fraction increases. However, the increase associated with the application of nanofluids is minor. Also the heat transfer of the zigzag micro channel is higher than that of the straight micro channel.