本文選題：有機朗肯循環(huán)　切入點：超臨界　出處：《華北電力大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：在低品位能源利用技術(shù)中,有機朗肯循環(huán)(ORC)發(fā)電技術(shù)具有熱效率高、設(shè)備簡單、環(huán)境友好等特點,得到了各國研究者的普遍重視。由于循環(huán)工質(zhì)物性對循環(huán)性能具有重要影響,因此工質(zhì)篩選成為ORC研究中最重要的方向之一。與亞臨界循環(huán)相比,超臨界循環(huán)中工質(zhì)無等溫沸騰段,能夠取得與熱源更優(yōu)的溫度匹配,有效提高循環(huán)熱效率。超臨界循環(huán)工質(zhì)篩選的研究中,存在三個關(guān)鍵科學(xué)問題：系統(tǒng)與熱源的耦合、運行參數(shù)對系統(tǒng)性能的影響、工質(zhì)物性的循環(huán)影響機理。 本文圍繞超臨界有機朗肯循環(huán)工質(zhì)篩選,首先提出一種系統(tǒng)與熱源耦合的熱力學(xué)計算新方法,即給定熱源的進(jìn)口溫度、出口溫度及質(zhì)量流量,在窄點約束下對工質(zhì)循環(huán)性能進(jìn)行計算分析。新方法采用Fortran語言編程尋優(yōu)并調(diào)用物性軟件Refprop9.0進(jìn)行求解。 其次,針對進(jìn)口溫度423.15K,出口溫度343.15K的低溫?zé)煔鉄嵩?選取三種典型工質(zhì)R218、R134a、R236fa,計算分析臨界溫度對循環(huán)性能的影響。提出了三種運行模式：(1)低臨界溫度工質(zhì)的靈活運行模式,即運行壓力與溫度為一矩形域；(2)中等臨界溫度工質(zhì)的分歧運行模式,即兩個運行壓力與某一運行溫度相對應(yīng)；(3)高臨界溫度的受限運行模式,即僅有一個運行壓力與某一運行溫度相對應(yīng)。提出了能夠量化蒸發(fā)器內(nèi)熱源流體與有機工質(zhì)流體溫度匹配程度的平均積分溫差。高臨界溫度工質(zhì)的蒸發(fā)器平均積分溫差較小,因此(?)效率較高,循環(huán)性能好。而低臨界溫度工質(zhì)蒸發(fā)器內(nèi)平均積分溫差大,循環(huán)性能較差。 最后,基于臨界溫度對循環(huán)性能的討論,在給定熱源下,選取高臨界溫度候選工質(zhì)進(jìn)行工質(zhì)篩選。通過比較循環(huán)熱效率、(?)效率及單位質(zhì)量凈輸出功,并綜合工質(zhì)的毒性、可燃性、環(huán)保性,發(fā)現(xiàn)在熱源溫度為423.15K的超臨界循環(huán)中,R134a為優(yōu)選工質(zhì)。R1234ze循環(huán)性能次之,但具有優(yōu)良的環(huán)保特性,建議應(yīng)用于環(huán)保要求較高的場所。 本文核心創(chuàng)新點在于在國際上最早明確了給定熱源溫度下基于工質(zhì)臨界溫度的篩選準(zhǔn)則,為超臨界ORC循環(huán)及工質(zhì)篩選提供了有價值的設(shè)計及運行依據(jù),主要工作發(fā)表在Energy上。
[Abstract]:In the low grade energy utilization technology, organic Rankine cycle (ORC) power generation technology has the advantages of high thermal efficiency, simple equipment and environmental friendly features, has received much attention of researchers all over the world. Because the circulation of refrigerants has an important effect on the cycle performance, so the refrigerant selection has become one of the most important direction in the research of ORC compared with subcritical cycle, supercritical circulating working fluid in non isothermal boiling section, and can obtain better heat source temperature, and effectively improve the thermal cycle efficiency. Research on supercritical refrigerant screening, there are three key issues: coupling system and heat source. The effects of operating parameters on the system performance. The influence mechanism of circulation of refrigerants.
This paper focuses on the supercritical organic Rankine cycle refrigerant selection, a new method to calculate the thermodynamics first proposed a system coupled with the heat source, heat source is given inlet temperature, outlet temperature and mass flow in the narrow constraints on refrigerant cycle performance are analyzed. A new method using Fortran language programming and optimization of software call Refprop9.0 is used to solve the problem.
Secondly, the inlet temperature of 423.15K outlet temperature of flue gas temperature, heat source 343.15K, select three typical refrigerants R218, R134a, R236fa, calculation and analysis of effect of critical temperature on the performance of the cycle is proposed. Three operation modes: (1) the flexible operation mode of low critical temperature of refrigerant, the operating pressure and temperature for a rectangular domain; (2) different operation mode of secondary critical temperature of refrigerant, namely two operating pressure with a corresponding operating temperature; (3) limited operation mode of high critical temperature, only one operating pressure and a corresponding operating temperature is proposed. The average temperature in the evaporator to integral quantization the heat source fluid and organic working fluid temperature matching degree. The average integral evaporator temperature smaller high critical temperature of refrigerant, so the efficiency is high, (?) and good cycling performance. The average integral temperature low critical temperature of refrigerant in the evaporator,. The ring performance is poor.
Finally, discuss the critical temperature on the performance of the cycle based on the given heat source, selection of high critical temperature of the working fluid of the candidate refrigerant selection. By comparing the thermal cycle efficiency, efficiency and quality of the unit (?) the net power output, and refrigerant toxicity, flammability, environmental protection, found in the heat source temperature is 423.15K the supercritical cycle, R134a is the preferred refrigerant.R1234ze cycle performance, but has excellent environmental protection characteristic, proposed applied to the environmental requirements of high places.
The core innovation of this paper is that the screening criteria based on working temperature critical temperature at the given heat source temperature were first identified internationally, which provided valuable design and operation basis for the supercritical ORC cycle and the selection of working fluids. The main work was published on Energy.

【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TM61

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