暫態液晶顯像技術應用於肋條與溝槽表面之熱傳與壓降分析

Abstract

本文以暫態液晶法量測正方形冷卻通道內部之局部熱傳係數，通道內部表面利用複合式冷卻技術來增進熱傳效果，藉由結合兩種以上之熱傳強化方法來達成。實驗測試主要分成兩類：(一)單純肋條(二)結合肋條與溝槽之複合式表面。所測試之肋條排列方式為垂直(90°)、傾斜(45°)、交錯、V型、及倒V型。實驗測試之雷諾數在15000 到 37000之間。肋條之距離高度比(p/e)為8，而肋條高度與通道水力直徑比(e/Dh)為0.1。實驗結果顯示45°傾斜肋條及V型肋條與溝槽熱傳效果最佳，而V型及倒V型肋條有最大的壓降。在散熱特性上45°傾斜肋條及V型肋條與溝槽為最佳。

This research presents the transient liquid crystal technique for local heat transfer coefficient measurements in a square channel. Compound cooling technique, by combining more than two heat transfer enhancement techniques, is applied on the surfaces of the square channel. The rib with and without groove configurations are tested: transverse (90°), angled (45°), discrete, V-shaped, and Inverted-V shaped. Reynolds numbers in the current study are from 15000 to 37000. The rib height-to-hydraulic diameter ratio is 0.1, and the rib pitch-to-height ratio is 8. Results show that the 45° ribs and V-shaped rib with groove have the maximum heat transfer enhancement and thermal performance. V-shaped and inverted-V ribs have the maximum friction loss.