本文選題：水平管內(nèi)蒸汽凝結(jié)　切入點：傳熱系數(shù)　出處：《大連理工大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：隨著我國經(jīng)濟的發(fā)展,淡水的需求量越來越大,水資源短缺日益嚴重�！秶摇笆濉笨茖W(xué)和技術(shù)發(fā)展規(guī)劃》中要求加快海水淡化技術(shù)的發(fā)展,特別是低溫多效蒸發(fā)(MED)海水淡化技術(shù)。水平管內(nèi)凝結(jié)現(xiàn)象是低溫多效蒸發(fā)海水淡化裝置中的主要傳熱過程之一,低溫多效蒸發(fā)海水淡化裝置中的管內(nèi)凝結(jié)現(xiàn)象具有小傳熱溫差、低質(zhì)量流率和較嚴格的流動阻力要求等特點,開展對水平管內(nèi)凝結(jié)的研究,探索強化傳熱方式,將為開發(fā)具有自主知識產(chǎn)權(quán)的海水淡化設(shè)備提供重要的技術(shù)依據(jù)和理論基礎(chǔ)。 水平管內(nèi)凝結(jié)廣泛存在于人們的生產(chǎn)和生活中。研究水平管內(nèi)凝結(jié)傳熱,對提高換熱器性能具有重要意義。為系統(tǒng)深入地研究水平管內(nèi)凝結(jié)過程,本文對水平管內(nèi)流型、傳熱系數(shù)分布和流動阻力進行了實驗研究和理論分析。主要研究內(nèi)容包括： (1)建立水平管內(nèi)凝結(jié)流動與傳熱實驗臺,對入口質(zhì)量流率0-8kg/(m2.s)、入口蒸汽飽和溫度45～70℃的水平管內(nèi)凝結(jié)流動與傳熱進行了實驗研究。 (2)根據(jù)對凝結(jié)液流動的觀測實驗,分析了蒸汽流量、干度、蒸汽飽和溫度對液位角的影響；對空隙率和液位角的計算模型進行了探討,并歸納出空隙率和液位角計算的經(jīng)驗公式。 (3)根據(jù)對水平管內(nèi)凝結(jié)傳熱系數(shù)的實驗研究,分析了分層流型對水平管內(nèi)傳熱的影響；討論了傳熱溫差、蒸汽飽和溫度、入口質(zhì)量流率和不凝結(jié)氣體含量等因素對傳熱過程的影響；分析了管內(nèi)傳熱系數(shù)沿管圓周方向的分布與液位角之間的關(guān)系；探討管內(nèi)凝結(jié)傳熱系數(shù)沿管長方向下降的原因；并分析了凝結(jié)液側(cè)和蒸汽側(cè)管內(nèi)傳熱系數(shù)的變化規(guī)律。 (4)根據(jù)對水平管內(nèi)流動阻力的實驗研究。分析了入口質(zhì)量流率、蒸汽雷諾數(shù)、蒸汽飽和溫度和傳熱溫差對管內(nèi)摩擦系數(shù)的影響；討論了蒸汽與凝結(jié)液界面表面粗糙度與氣液間剪切力的關(guān)系。 (5)綜合流型觀測、傳熱系數(shù)和流動阻力測量結(jié)果,討論了入口質(zhì)量流率、傳熱溫差和蒸汽飽和溫度對水平管凝結(jié)傳熱量的影響,分析最優(yōu)出口干度的變化規(guī)律。 (6)本文在雙極坐標系下,采用低雷諾數(shù)模型,計算了水平管內(nèi)的液位高度、流動阻力和速度場分布,并分析了氣相和液相的物性變化對液位高度和流動阻力的影響。
[Abstract]:With the development of China's economy, the demand for fresh water is increasing, and the shortage of water resources is becoming more and more serious. The 12th Five-Year Plan for Scientific and technological Development of China calls for speeding up the development of seawater desalination technology. The condensation phenomenon in horizontal tube is one of the main heat transfer processes in low temperature multi-effect evaporative seawater desalination unit, and the condensation phenomenon in low temperature multi-effect evaporation seawater desalination device has small heat transfer temperature difference. With the characteristics of low mass flow rate and strict flow resistance, the study of condensation in horizontal pipe and the exploration of enhanced heat transfer mode will provide important technical and theoretical basis for the development of seawater desalination equipment with independent intellectual property rights. Condensation in horizontal tube is widely existed in people's production and life. It is very important to study condensation heat transfer in horizontal tube to improve the performance of heat exchanger. In order to study the condensation process in horizontal tube systematically, the flow pattern in horizontal tube is studied in this paper. The distribution of heat transfer coefficient and flow resistance are studied experimentally and theoretically. The condensation flow and heat transfer in a horizontal tube are studied experimentally at the inlet mass flow rate of 0 ~ 8 kg / m ~ 2 路s ~ 2 路s ~ (-1) and the inlet vapor saturation temperature at 4570 鈩，

本文編號：1615318