【摘要】：太陽(yáng)能熱發(fā)電廠一般建在缺水的華北、東北、西北等“三北”地區(qū),而復(fù)合循環(huán)空冷技術(shù)可以解決缺水的問(wèn)題,而且比直接空冷技術(shù)更加有優(yōu)勢(shì)。本文基于復(fù)合循環(huán)空冷(復(fù)間冷)系統(tǒng)的組成和傳熱過(guò)程,定性分析了雙相變換熱器(凝汽器)的管壁溫度、液氨進(jìn)口流速、入口溫度對(duì)凝汽器換熱的影響,確定了復(fù)間冷凝汽器換熱的影響因素,建立了復(fù)間冷機(jī)組變工況特性下凝汽器換熱器的計(jì)算模型,并以凝汽器最佳換熱為目標(biāo),給出運(yùn)行工況復(fù)間冷系統(tǒng)最佳換熱面積的計(jì)算方法。以張北地區(qū)某50MW太陽(yáng)能熱發(fā)電復(fù)間冷系統(tǒng)機(jī)組參數(shù)為基準(zhǔn),通過(guò)分析計(jì)算,揭示了復(fù)間冷機(jī)組凝汽器最佳換熱規(guī)律,所得結(jié)果可為復(fù)間冷系統(tǒng)設(shè)計(jì)和運(yùn)行優(yōu)化提供可靠理論依據(jù)。(1)對(duì)電站空冷雙相變換熱器換熱管內(nèi)氨進(jìn)行汽液兩相流蒸發(fā)沸騰的數(shù)值模擬,將換熱器簡(jiǎn)化為研究單根水平換熱管,分析了不同管壁溫度、液氨進(jìn)口流速、入口溫度對(duì)沸騰傳熱性能的影響。研究表明:隨著管壁溫度的升高,會(huì)導(dǎo)致管內(nèi)換熱系數(shù)變小;隨著液氨進(jìn)口流速的增加,管內(nèi)換熱性能在增加,同時(shí)管內(nèi)壓力也在降低;隨著液氨進(jìn)口溫度的增加,管內(nèi)換熱性能在下降,而壓力幾乎沒(méi)有變化。(2)確定雙相變換熱器的最優(yōu)管壁溫度、進(jìn)口流速、入口溫度的組合形式。結(jié)果表明:壁面溫度為302.96K、進(jìn)口流速為0.1m/s、入口溫度為278.15K時(shí)換熱管的換熱效果最佳。確定了凝汽器最優(yōu)管壁溫度、液氨進(jìn)口流速、入口溫度組合方式結(jié)合電站實(shí)際運(yùn)行環(huán)境可以確定換熱器的最佳換熱面積。(3)本文建立了逆制冷循環(huán)空冷系統(tǒng)發(fā)電模型,并采用EES(Engineering Equation Solver)軟件編程,對(duì)逆制冷系統(tǒng)模型進(jìn)行模擬計(jì)算。通過(guò)系統(tǒng)的性能分析和熱力優(yōu)化研究。本文從朗肯系統(tǒng)的性能指標(biāo)作為出發(fā)點(diǎn),分別分析不可逆損失、膨脹機(jī)輸出功率、系統(tǒng)熱效率和?效率對(duì)系統(tǒng)的影響,選取了蒸發(fā)溫度、冷凝溫度、過(guò)熱度、冷凝度、環(huán)境溫度、膨脹機(jī)等熵效率這幾個(gè)影響參數(shù)作為系統(tǒng)存在的自變量。對(duì)系統(tǒng)有利的自變量是蒸發(fā)溫度、環(huán)境溫度、膨脹機(jī)等熵效率,對(duì)系統(tǒng)不利的自變量是冷凝溫度,過(guò)熱度對(duì)系統(tǒng)性能的影響不大,過(guò)冷度對(duì)整個(gè)系統(tǒng)是有利的,但是受益并不是很大。(4)建立了正制冷循環(huán)空冷系統(tǒng)模型,運(yùn)用EES進(jìn)行模擬計(jì)算,計(jì)算得到蒸發(fā)溫度和環(huán)境溫度對(duì)系統(tǒng)是有利因素;冷凝溫度和過(guò)熱度對(duì)系統(tǒng)是不利因素;過(guò)冷度對(duì)系統(tǒng)是沒(méi)有影響的。
[Abstract]:Solar thermal power plants are generally built in the "three northern" regions, such as North China, Northeast, Northwest, etc. The composite cycle air cooling technology can solve the problem of water shortage, and has more advantages than direct air cooling technology. Based on the composition and heat transfer process of the compound cycle air cooling system, the effects of the tube wall temperature, the inlet velocity of ammonia and the inlet temperature on the heat transfer of the double phase change heat exchanger (condenser) are qualitatively analyzed in this paper. The factors affecting the heat transfer of the complex intercooler condenser are determined, and the calculation model of the condenser heat exchanger under the variable working condition characteristic of the complex intercooler unit is established, and the optimum heat transfer of the condenser is taken as the goal. The calculation method of optimum heat transfer area of complex intercooling system under operating condition is given. Based on the parameters of a 50MW solar complex cooling system in Zhangbei area, the optimum heat transfer law of the condenser is revealed through analysis and calculation. The results can provide a reliable theoretical basis for the design and operation optimization of the complex intercooling system. (1) numerical simulation of vapor-liquid two-phase flow evaporation boiling of ammonia in the heat exchanger tube of air-cooled double-phase heat exchanger in power station. The heat exchanger was simplified into a single horizontal heat exchanger. The effects of different tube wall temperature, inlet flow rate of ammonia and inlet temperature on boiling heat transfer performance were analyzed. The results show that the heat transfer coefficient decreases with the increase of the temperature of the tube wall, the heat transfer performance increases with the increase of the inlet velocity of ammonia, and the pressure in the tube decreases. With the increase of the inlet temperature of liquid ammonia, the heat transfer performance of the tube is decreasing, but the pressure is almost unchanged. (2) the optimal wall temperature, inlet velocity and inlet temperature of the double phase change heat exchanger are determined. The results show that the heat transfer efficiency of the tube is the best when the wall temperature is 302.96K, the inlet velocity is 0.1m / s, and the inlet temperature is 278.15K. The optimal tube wall temperature, inlet ammonia flow rate and inlet temperature combination of condenser can be used to determine the optimal heat transfer area of the heat exchanger combined with the actual operating environment of the power station. (3) in this paper, a power generation model of the inverse refrigeration cycle air cooling system is established. The inverse refrigeration system model is simulated and calculated by using EES (Engineering Equation Solver) software. Through the system performance analysis and thermodynamic optimization research. In this paper, the irreversible loss, output power of expander, thermal efficiency and thermal efficiency of Rankine system are analyzed respectively from the point of view of Rankine system performance index. The effect of efficiency on the system is studied. The influence parameters such as evaporation temperature, condensation temperature, superheat degree, condensation degree, ambient temperature and entropy efficiency of expander are selected as independent variables of the system. The favorable independent variables to the system are evaporation temperature, ambient temperature, entropy efficiency of expander, and the unfavorable independent variable to the system is the condensation temperature. The superheat has little effect on the system performance, and the undercooling is beneficial to the whole system. But the benefit is not very great. (4) the air cooling system model of the positive refrigeration cycle is established, and the evaporation temperature and the ambient temperature are the favorable factors to the system. Condensation temperature and superheat are unfavorable factors to the system, while undercooling has no effect on the system.
【學(xué)位授予單位】：東北電力大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TM621

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