超臨界二氧化碳在微通道氣體冷卻器內的熱傳及壓降特性研究

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Title:	超臨界二氧化碳在微通道氣體冷卻器內的熱傳及壓降特性研究
Authors:	廖崑傑;Liao,Kun-Chieh
Contributors:	機械工程學系
Keywords:	二氧化碳;超臨界;微通道;熱傳;壓降;carbon dioxide;supercritical;microchannel;heat transfer;pressure drop
Date:	2013-07-16
Issue Date:	2013-08-22 12:16:18 (UTC+8)
Publisher:	國立中央大學
Abstract:	本文以實驗的方法分析超臨界二氧化碳，在0.5 mm×0.5 mm多管並排方形微通道中穿越超臨界區域冷卻的熱傳及壓降特性。結果顯示在離臨界點遠處，壓降與傳統經驗式的預估值差異在3.5 %以內；在接近臨界點時，與以局部性質估算值有30 %偏差，但若以入出口溫度範圍內積分後的性質代入計算，與傳統經驗式預測的差異值可降至10 %以內。在穿越超臨界區域過程中，靠近臨界點時二氧化碳性質變化劇烈，因此計算穿越超臨界過程的熱傳係數時，所使用的氣體性質非常重要，以冷媒入出口之間溫度積分性質計算所得之熱傳係數會比直接使用入出口平均溫對應之性質所得之熱傳係數更加準確。 This thesis presents the experimental data for the heat transfer and pressure drop characteristics during the gas cooling process of carbon dioxide in a 37-channel horizontal extruded aluminum micro-tube, each channel with inside dimension of 0.5mm x 0.5mm. The results showed that data at the distant from critical point the pressure drop agree very well with those calculated by the traditional correlation using local property within a deviation of 3.5 %, however the result deviates up to 30 % close to critical points, when the integration property in the temperature range of inlet and outlet is used, the deviation closing to the critical point can be reduced to be within 10 %. Crossing the supercritical region, the carbon dioxide gas property changes very dramatically, so the used property for heat transfer coefficient calculation near the critical point region is very important, the heat transfer coefficient calculated by using the integration property in the temperature range of inlet and outlet is better than that calculated by using the property of average temperature of inlet and outlet.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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