【摘要】：在全球化石能源緊缺、環(huán)境日益惡劣的大形勢(shì)下,新能源開發(fā)、余熱利用成為解決當(dāng)下日趨惡劣的能源狀況的必要舉措。利用有機(jī)朗肯循環(huán)技術(shù)(Organic Rankine Cycle,ORC)對(duì)地?zé)崮苓M(jìn)行高效利用,將極大地緩解當(dāng)下的能源緊張情況。向心式渦輪膨脹機(jī)作為有機(jī)朗肯循環(huán)系統(tǒng)的核心部件,擁有良好的發(fā)展前景,對(duì)于中低溫?zé)嵩椿厥绽玫膱?chǎng)合,采用向心式渦輪膨脹機(jī)可實(shí)現(xiàn)較高的轉(zhuǎn)換效率。本文利用有機(jī)朗肯循環(huán)技術(shù)對(duì)95℃低溫地?zé)崮苓M(jìn)行機(jī)理分析,設(shè)計(jì)地?zé)崮躉RC發(fā)電系統(tǒng),對(duì)低溫地?zé)崮苡袡C(jī)朗肯循環(huán)發(fā)電系統(tǒng)進(jìn)行熱力學(xué)分析,并對(duì)系統(tǒng)蒸發(fā)溫度、過熱度及過冷度等主要參數(shù)進(jìn)行優(yōu)化分析。結(jié)果表明對(duì)于基本有機(jī)朗肯循環(huán),系統(tǒng)循環(huán)熱效率和膨脹機(jī)輸出功隨蒸發(fā)溫度的升高成遞增趨勢(shì),膨脹機(jī)進(jìn)出口溫差的增大可顯著提高系統(tǒng)的循環(huán)熱效率;過熱溫度對(duì)ORC系統(tǒng)的影響與普通朗肯循環(huán)的影響不同,它與有機(jī)工質(zhì)的熱物性和系統(tǒng)工況有關(guān)。隨著過熱溫度的增大,系統(tǒng)循環(huán)熱效率先增加后減小,出現(xiàn)最大循環(huán)熱效率及最優(yōu)過熱溫度。根據(jù)系統(tǒng)參數(shù)對(duì)50kW渦輪膨脹機(jī)進(jìn)行熱力學(xué)計(jì)算,導(dǎo)葉和葉輪的三維設(shè)計(jì),利用Ansys軟件中CFX模塊對(duì)導(dǎo)葉及葉輪內(nèi)部流場(chǎng)進(jìn)行分析,最后采用均勻設(shè)計(jì)試驗(yàn)方法,對(duì)渦輪膨脹機(jī)葉輪進(jìn)行優(yōu)化。模擬結(jié)果顯示在葉輪葉片前緣及尾緣存在沖擊損失及尾跡損失,在葉輪30%相對(duì)弦長(zhǎng)處存在過度膨脹,產(chǎn)生局部低壓區(qū),同時(shí)存在由輪轂至輪緣的二次流流動(dòng)。在合理的取值范圍內(nèi)采用較小的輪徑比可以減少葉輪流道流動(dòng)損失;在相對(duì)弦長(zhǎng)30%左右靠近輪緣區(qū)域,工質(zhì)流動(dòng)方向發(fā)生較大轉(zhuǎn)折,與輪緣壁面產(chǎn)生局部低能團(tuán),存在較大熵增區(qū);在葉輪出口尾緣處,由于尾跡損失存在低速流動(dòng)氣流,并且低速流體與主流體發(fā)生混摻效應(yīng),部分機(jī)械能轉(zhuǎn)化為工質(zhì)的熱能,造成損失的進(jìn)一步加大;輪緣與輪轂側(cè)由于附面層的存在,較中間區(qū)域熵增明顯;在取值范圍內(nèi)采用較大的子午面流道寬度,葉輪對(duì)出口氣流控制作用增大,有利于減少葉輪流道流動(dòng)損失,提高膨脹機(jī)效率。
[Abstract]:Under the situation of global fossil energy shortage and increasingly bad environment, the development of new energy and the utilization of surplus heat become the necessary measures to solve the worsening energy situation. Using organic Rankine cycle technology (Organic Rankine Cycle,ORC) to utilize geothermal energy efficiently will greatly alleviate the current energy stress. As the core component of organic Rankine cycle system, the centripetal turbine expander has a good prospect of development. In the case of heat source recovery and utilization at medium and low temperature, the use of the concentric turbine expander can achieve higher conversion efficiency. In this paper, the mechanism of low temperature geothermal energy at 95 鈩，

本文編號(hào)：2380628