缸內直噴點燃式甲醇發(fā)動機非常規(guī)排放仿真研究

發(fā)布時間：2018-07-06 10:28

本文選題：缸內直噴 + 甲醇發(fā)動機��；參考：《吉林大學》2015年碩士論文

【摘要】：隨著能源危機和環(huán)境危機日益加劇，尋求一種清潔的可替代燃料迫在眉睫。經過多年的探索，人們開始將目光轉向了甲醇。甲醇,化學分子式為CH3OH，具有和汽油、柴油媲美的儲存運輸和應用方面的優(yōu)勢，同時在常規(guī)排放性能方面比傳統(tǒng)燃料更優(yōu)，所以甲醇被公認為是21世紀最具發(fā)展?jié)摿Φ拇萌剂�。除了以上種種優(yōu)勢，甲醇燃料的應用也面臨不少問題亟待解決，，特別是甲醇燃料帶來的非常規(guī)排放問題，嚴重制約了甲醇燃料的大規(guī)模應用。本文以一臺經柴油機改裝的缸內直噴點燃式甲醇發(fā)動機為原型，通過三維建模軟件Pro/E對模型進行精簡優(yōu)化并將模型以*.stl格式導出，采用AVL-FIRE軟件對模型進行前處理，使用AVL-FIRE軟件耦合甲醇詳細氧化機理進行模擬計算，用仿真計算得到的缸壓曲線與實驗所測的缸壓曲線進行對比驗證以確保仿真計算的準確性。通過模擬計算研究進氣溫度（過量空氣系數(shù)）、點火正時、噴油正時對冷啟動和穩(wěn)態(tài)工況非常規(guī)排放影響，得到以下結論：一、冷啟動工況： 1.提高進氣溫度能促進甲醇霧化及蒸發(fā)，改善缸內混合氣分布，提高缸內混合氣燃燒質量，有效降低未燃甲醇和甲醛排放；當進氣溫度從283K提高到313K未燃甲醇和甲醛的排放能夠得到極大改善；當進氣溫度達到313K繼續(xù)提高進氣溫度對降低未燃甲醇和甲醛的排放效果不明顯。 2.推遲點火正時，缸內混合氣分布惡化，燃燒惡化，未燃甲醇和甲醛排放升高；當點正時由20°CA BTDC推遲到11°CA BTDC未燃甲醇和甲醛排放增加不明顯；當點火正時由11°CA BTDC推遲到8°CABTDC時未燃甲醇和甲醛排放會急劇增加。 3.推遲噴油正時，缸內混合氣分布得到優(yōu)化，燃燒更加充分，有效降低未燃甲醇和甲醛排放；當噴油正時為57°CA BTDC時未燃甲醇和甲醛排放最高，隨著噴油正時推遲未燃甲醇和甲醛排放呈遞減趨勢；但是當噴油正時為49°CA BTDC時由于缸內燃燒溫度維持在1000K左右會促進未燃甲醇不完全氧化成甲醛使得甲醛排放達到峰值，當噴油正時進一步推遲甲醛排放明顯下降。二、穩(wěn)態(tài)工況： 1.增大過量空氣系數(shù)，不利于混合氣形成，燃燒惡化，未燃甲醇和甲醛排放增加；當過量空氣系數(shù)由λ=1.5增加到λ=2.5未燃甲醇甲醛排放增加不明顯；當過量空氣系數(shù)增加到λ=3.0未燃甲醇和甲醛排放急劇增加。 2.推遲點火正時，缸內混合氣分布惡化，燃燒惡化，未燃甲醇和甲醛排放增加；當點火正時由20°CA BTDC推遲到11°CA BTDC未燃甲醇和甲醛排放有輕微增加；當點火正時推遲到8°CABTDC未燃甲醇和甲醛排放急劇增加。 3.推遲噴油正時，能有效改善缸內混合氣分布，燃燒質量提高，未燃甲醇和甲醛排放顯著降低；當噴油正時為57°CA BTDC時未燃甲醇和甲醛排放十分高；當噴油正時推遲到53°CA BTDC未燃甲醇和甲醛排放有顯著降低；當噴油正時進一步推遲未燃甲醇和甲醛排放降輕微降低。
[Abstract]:With the increasing of energy crisis and environmental crisis , it is urgent to seek a clean alternative fuel . After many years of exploration , people have begun to turn their attention to methanol . Methanol and chemical molecular formula CH3OH have the advantages of storage transportation and application as well as gasoline and diesel oil . At the same time , methanol is recognized as a substitute fuel with the most development potential in the 21st century . In addition to the above advantages , the application of methanol fuel has many problems to be solved , especially the problem of unconventional discharge caused by methanol fuel , which seriously restricts the large - scale application of methanol fuel .

In this paper , a diesel engine modified in - cylinder direct injection ignition methanol engine is used as a prototype , and the model is optimized by three - dimensional modeling software Pro / E and the model is derived in the form of * . stl . The simulation calculation is carried out on the model by using the software Pro / E . The cylinder pressure curve obtained by the simulation is compared with the cylinder pressure curve measured by the experiment to ensure the accuracy of the simulation calculation .

I . Cold start working condition :

1 , increasing the intake air temperature , promoting methanol atomization and evaporation , improving the distribution of the in - cylinder mixture , improving the combustion quality of the in - cylinder mixture , and effectively reducing unburned methanol and formaldehyde emission ;
When the inlet temperature is increased from 283K to 313K , the discharge of unburned methanol and formaldehyde can be greatly improved ;
When the intake air temperature reaches 313K , the effect of increasing the intake air temperature on reducing unburned methanol and formaldehyde is not obvious .

2 . When the ignition timing is retarded , the distribution of the in - cylinder mixture deteriorates , the combustion deteriorates , the unburned methanol and the formaldehyde emission increase ;
When the ignition timing was retarded from 20 擄 CA BTDC to 11 擄 CA BTDC unburned methanol and formaldehyde emission increased obviously ;
Unburned methanol and formaldehyde emissions increase sharply when the ignition timing is retarded from 11 擄 CA BTDC to 8 擄 CABTDC .

3 . When the fuel injection timing is delayed , the distribution of the in - cylinder mixture is optimized , the combustion is more fully , the unburned methanol and formaldehyde emission are effectively reduced ;
When the fuel injection timing was 57 擄 CA BTDC , unburned methanol and formaldehyde were the highest , and the emission of unburned methanol and formaldehyde was decreased with the fuel injection timing .
However , when the fuel injection timing is 49 擄 CA BTDC , the combustion temperature in the cylinder is maintained around 1000K to promote the incomplete oxidation of unburned methanol to formaldehyde so that the formaldehyde emission reaches the peak value , and the emission of formaldehyde is further delayed when the injection timing is positive .

II . Steady - state operating conditions :

1 . Increasing the excess air coefficient is not conducive to the formation of the mixed gas , the combustion deteriorates , the unburned methanol and the formaldehyde emission increase ;
When the excess air coefficient increases from 位 = 1.5 to 位 = 2.5 , the formaldehyde emission of unburned methanol is not obvious ;
When the excess air factor increases to 位 = 3.0 unburned methanol and formaldehyde emissions sharply increase .

2 . When the ignition timing is retarded , the distribution of the in - cylinder mixture deteriorates , combustion deteriorates , unburned methanol and formaldehyde emission increase ;
When the ignition timing was retarded from 20 擄 CA BTDC to 11 擄 CA BTDC unburned methanol and formaldehyde emissions slightly increased ;
When the ignition timing was retarded to 8 擄 CABTDC unburned methanol and formaldehyde emissions sharply increased .

3 . When the fuel injection timing is delayed , the in - cylinder mixed gas distribution can be effectively improved , the combustion quality is improved , the unburned methanol and the formaldehyde emission are obviously reduced ;
Unburned methanol and formaldehyde emissions were very high when the fuel injection timing was 57 擄 CA BTDC ;
When the injection timing was retarded to 53 擄 CA BTDC unburned methanol and formaldehyde emission decreased significantly ;
A slight decrease in unburned methanol and formaldehyde emissions was further delayed when the injection timing was positive .
【學位授予單位】：吉林大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TK401

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