【摘要】：傾斜管內(nèi)有機(jī)工質(zhì)冷凝換熱在工業(yè)生產(chǎn)中廣泛應(yīng)用,掌握其傳熱規(guī)律可以優(yōu)化換熱設(shè)備,節(jié)約能源。當(dāng)前研究主要集中在小管徑的空調(diào)管等,而隨著ORC等低品位能源的興起,冷凝管徑逐漸增大,因此,本文依托北京市低品位能源與多相流動(dòng)傳熱重點(diǎn)實(shí)驗(yàn)室,通過實(shí)驗(yàn)研究較大管徑傾斜管內(nèi)R245fa冷凝傳熱。本文在內(nèi)徑14.81mm,長(zhǎng)1200mm的傾斜管內(nèi)進(jìn)行R245fa對(duì)流冷凝傳熱實(shí)驗(yàn)。實(shí)驗(yàn)工況為：R245fa質(zhì)量流速200～700 kg/m2s,入口干度0.1～0.9,相應(yīng)的弗勞德數(shù)為0.174～2.153,實(shí)驗(yàn)段入口飽和溫度55.5℃,實(shí)驗(yàn)段傾角從垂直向下變化到垂直向上,分別為θ=-0°、±4°、±8°、±15°、±30°、±45°、±60°、±900°實(shí)驗(yàn)中流型主要為分層流、間歇流和環(huán)狀流。實(shí)驗(yàn)結(jié)果表明：冷凝傳熱系數(shù)隨傾角增大有上升趨勢(shì),且在弗勞德數(shù)遠(yuǎn)小于1時(shí),上升趨勢(shì)明顯,隨著弗勞德數(shù)增大至1并繼續(xù)增大,上升趨勢(shì)逐漸消失。在水平角度及其附近微傾角范圍內(nèi),無(wú)論增大或者減小傾角,其傳熱系數(shù)相對(duì)于水平角傳熱系數(shù)均增大。在整個(gè)傾角范圍內(nèi),傳熱系數(shù)隨角度成非線性波動(dòng)趨勢(shì)。通過可視化分析傳熱規(guī)律得出結(jié)論：角度增加時(shí),汽液界面形成強(qiáng)烈的界面波,強(qiáng)化傳熱。角度下降時(shí),液位降低,熱阻減小,強(qiáng)化傳熱。在不同傾角下,界面波、液位高度、流型、重力、慣性力等多因素共同作用,相互競(jìng)爭(zhēng),引起了傳熱系數(shù)的波動(dòng)趨勢(shì)。同時(shí),針對(duì)傳熱系數(shù)隨角度的增大及波動(dòng)趨勢(shì),擬合出關(guān)于角度的冷凝傳熱關(guān)聯(lián)式,其平均誤差及均方根誤差分別為6.36%、5.97%。
[Abstract]:The condensation and heat transfer of organic working fluid in inclined tube is widely used in industrial production. To master the heat transfer law can optimize the heat transfer equipment and save energy. At present, the research is mainly focused on the air conditioning tubes with small pipe diameter, but with the rise of low-grade energy sources such as ORC, the condensing pipe diameter is gradually increasing. Therefore, this paper relies on the Beijing key Laboratory of Low-grade Energy and Multiphase flow Heat transfer. The condensation heat transfer of R245fa in inclined tube with large diameter was studied experimentally. In this paper, R245fa convection condensation heat transfer experiments are carried out in an inclined tube with an inner diameter of 14.81 mm and a long 1200mm. The experimental conditions are as follows: the inlet dryness of the R245fa mass flow rate 200,700 kg/m2s, is 0.1g / 0.9, the corresponding Froude number is 0.174n2.153, and the inlet saturation temperature of the experiment section is 55.5 鈩，

本文編號(hào)：2328098