發(fā)布時(shí)間：2018-03-23 10:46

  本文選題：蒸發(fā)器和冷凝器　切入點(diǎn)：夾點(diǎn)溫差　出處：《重慶大學(xué)》2014年碩士論文

【摘要】：能源問(wèn)題已經(jīng)成為全球經(jīng)濟(jì)發(fā)展的最大壓力之一�，F(xiàn)代工業(yè)生產(chǎn)中造成了大量低溫余熱的排放，因此回收低溫余熱能源將其用來(lái)發(fā)電有很大的意義。目前應(yīng)用最廣泛的低溫余熱發(fā)電系統(tǒng)主要是有機(jī)朗肯循環(huán)系統(tǒng)(Organic Rankine CycleSystem，ORCs)。作為ORCs中的關(guān)鍵部件，蒸發(fā)器和冷凝器的性能對(duì)整個(gè)系統(tǒng)有很大影響，而其中重要的操作參數(shù)夾點(diǎn)溫差的選擇和匹配，成為ORCs研究的又一新問(wèn)題。因此，本課題運(yùn)用熱經(jīng)濟(jì)學(xué)原理，擬對(duì)有機(jī)朗肯循環(huán)系統(tǒng)中的蒸發(fā)器和冷凝器夾點(diǎn)溫差進(jìn)行優(yōu)化和匹配。研究的主要內(nèi)容如下： ①以R600a為工質(zhì)，構(gòu)建亞臨界ORCs的蒸發(fā)器熱經(jīng)濟(jì)性模型，分別從火用回收和火用損失兩個(gè)角度來(lái)探討蒸發(fā)器夾點(diǎn)溫差對(duì)蒸發(fā)器性能的影響，并對(duì)夾點(diǎn)溫差進(jìn)行優(yōu)化，分析相關(guān)操作參數(shù)和經(jīng)濟(jì)參數(shù)等對(duì)優(yōu)化結(jié)果的影響。結(jié)果表明：存在最佳的蒸發(fā)器夾點(diǎn)溫差ΔTe,opt，使蒸發(fā)器的性能最佳；從火用回收的角度優(yōu)化的蒸發(fā)器夾點(diǎn)溫差與從火用損失的角度優(yōu)化的結(jié)果相比略大；本部分優(yōu)化的蒸發(fā)器夾點(diǎn)溫差的范圍為5 12K，優(yōu)化結(jié)果與經(jīng)濟(jì)因素有關(guān)；最優(yōu)蒸發(fā)器夾點(diǎn)溫差隨余熱煙氣與工質(zhì)的熱容率之比R的增大而增大，隨蒸發(fā)器預(yù)熱段換熱系數(shù)KeA、蒸發(fā)段與預(yù)熱段換熱系數(shù)比1、熱量火用價(jià)ce的增大而減��；流動(dòng)火用損失對(duì)最優(yōu)蒸發(fā)器夾點(diǎn)溫差的影響很小，，可以忽略。 ②以采用純工質(zhì)R601a、R245fa，混合工質(zhì)R13I1/R601a、R245fa/R601a的亞臨界ORCs為研究對(duì)象，分析蒸發(fā)器和冷凝器夾點(diǎn)溫差對(duì)系統(tǒng)性能的影響，通過(guò)分析影響因素，對(duì)二者進(jìn)行優(yōu)化和匹配。結(jié)果表明：存在最優(yōu)的蒸發(fā)器夾點(diǎn)溫差ΔTe,opt和最優(yōu)的冷凝器與蒸發(fā)器夾點(diǎn)溫差比yopt；ΔTe,opt范圍為3 6K，與其他文獻(xiàn)中提到的范圍相比偏��；yopt優(yōu)化結(jié)果范圍為0.8 1.5；優(yōu)化結(jié)果受以下幾個(gè)參數(shù)如冷凝器與蒸發(fā)器換熱系數(shù)之比2、混合工質(zhì)在冷凝器中的露點(diǎn)溫度T1a、混合工質(zhì)的組分變化的影響較大；而工質(zhì)在蒸發(fā)器中的泡點(diǎn)溫度T3a、余熱煙氣的質(zhì)量流量mg、進(jìn)口溫度Tgi等對(duì)優(yōu)化的結(jié)果影響很小。并對(duì)四種不同工質(zhì)R601a、R245fa，R13I1/R601a、R245fa/R601a的優(yōu)化結(jié)果進(jìn)行了比較分析。 ③以采用R143a為工作流體的跨臨界ORCs為研究對(duì)象，分析蒸發(fā)器和冷凝器夾點(diǎn)溫差對(duì)系統(tǒng)性能的影響及影響二者優(yōu)化的因素，并將優(yōu)化的結(jié)果與亞臨界ORCs的結(jié)論進(jìn)行比較分析。結(jié)果表明：跨臨界ORCs中也存在ΔTe,opt和yopt；冷凝器與蒸發(fā)器換熱系數(shù)之比2、工質(zhì)在膨脹機(jī)的出口壓力P1、煙氣的質(zhì)量流量mg和進(jìn)口溫度Tgi都會(huì)影響ΔTe,opt和yopt。
[Abstract]:Energy has become one of the biggest pressures on global economic development. At present, the most widely used low temperature waste heat power generation system is organic Rankine cycle system ORCs, which is a key component in ORCs. The performance of evaporator and condenser has a great influence on the whole system, and the choice and matching of the temperature difference of the important operating parameters become another new problem in the research of ORCs. The temperature difference between evaporator and condenser in organic Rankine circulatory system is optimized and matched. The main contents of the study are as follows:. 1 using R600a as working medium, the thermal economic model of subcritical ORCs evaporator is constructed. The influence of temperature difference at pinch point of evaporator on evaporator performance is discussed from exergy recovery and exergy loss respectively, and the temperature difference of pinch point is optimized. The effects of relevant operation parameters and economic parameters on the optimization results are analyzed. The results show that the optimum temperature difference between evaporator pinch points 螖 Teopt makes the evaporator performance the best. Compared with the result from exergy loss, the optimized temperature difference of evaporator from exergy recovery angle is slightly larger than that from the angle of exergy loss, the range of temperature difference of evaporator pinch point of this part is 5 ~ 12K, and the optimization result is related to economic factors. The optimal temperature difference increases with the increase of heat capacity ratio R of waste heat smoke to working fluid, and decreases with the increase of heat transfer coefficient KeA in preheating section of evaporator, the ratio of heat transfer coefficient of evaporation section to preheating section of evaporator and the heat exergy value ce of evaporator. The effect of exergy loss on the temperature difference of the optimal evaporator is negligible. (2) the subcritical ORCs with pure working fluid R601a / R245faand mixed refrigerant R13I1 / R601a / R245fa / R601a was used as the research object to analyze the effect of temperature difference between evaporator and condenser on the performance of the system. The results show that there are optimal temperature difference between condenser and evaporator, and the range of 螖 Teopt is 3 ~ 6K, which is smaller than the range mentioned in other literatures, and the optimal ratio of temperature difference between condenser and evaporator is yopt.The results show that the optimum temperature difference between evaporator and condenser is smaller than that mentioned in other literatures. The optimum results were influenced by the following parameters, such as the ratio of condenser to evaporator heat transfer coefficient 2, the dew point temperature T 1a of mixed working fluid in the condenser, and the change of composition of mixed working fluid. However, the Bubble point temperature T 3a, the mass flow rate of waste heat flue gas, and the inlet temperature Tgi have little effect on the optimized results, and the optimized results of R245fa1 / R601a / R245far / R601a of four different working fluids are compared and analyzed. Taking transcritical ORCs with R143a as working fluid as the research object, the influence of temperature difference between evaporator and condenser on the system performance and the factors influencing their optimization are analyzed. The optimized results are compared with the results of subcritical ORCs. The results show that there are 螖 Teopt and yop t in transcritical ORCs, the ratio of heat transfer coefficient between condenser and evaporator is 2, the working fluid is at the outlet pressure of expander P1, and the mass flow of flue gas is obtained. Both the dose of mg and the inlet temperature Tgi could affect 螖 Teanopt and yop _ t.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TM617

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