本文選題：汽油機 + 摻氫�。� 參考：《吉林大學》2017年博士論文

【摘要】：在我國經(jīng)濟快速發(fā)展的背景下,汽車的保有量逐年攀升,這就使我國的石油需求量不斷增加,而對于我國這樣一個石油資源貧乏的國家來說已成為限制國家發(fā)展的一個重要因素。同時,汽車尾氣帶來的空氣污染已嚴重的影響了人們的生活。因此,全世界都在致力于開發(fā)代用燃料和減少汽車尾氣排放的研究。而氫氣既可以作為代用燃料,又可以將其加入汽油機中來調(diào)節(jié)汽油機的性能及排放。目前為止所查閱到的關(guān)于摻氫汽油機的文獻中大多以氫氣和汽油都為進氣道噴射的研究為主,而本文所進行的試驗采用了氫氣缸內(nèi)直噴、汽油進氣道噴射的方式,其最大的優(yōu)勢是可以有效的避免回火現(xiàn)象的產(chǎn)生。本文首先對噴氫過程進行了仿真以確定最佳的噴氫時刻。然后,進行了氫氣汽油混合燃料火花點火發(fā)動機的臺架試驗,并分析了摻氫比,過量空氣系數(shù)、點火提前角和EGR率對摻氫汽油機性能和排放的影響。利用臺架試驗所得的數(shù)據(jù)通過灰色關(guān)聯(lián)度計算方法求出了每個影響因素與摻氫汽油機各個性能及排放參數(shù)之間的灰色關(guān)聯(lián)度,并使用灰色關(guān)聯(lián)分析法分析了摻氫汽油機性能和排放的各個參數(shù)受哪些因素的影響及影響程度。最后建立了神經(jīng)網(wǎng)絡(luò)模型,并對摻氫汽油機的性能和排放進行了預測。本文主要的結(jié)論總結(jié)如下:隨著點火提前角的增大,NOX、HC和CO排放都隨之增加。最佳點火提前角隨著摻氫體積分數(shù)的增加而減小。隨著過量空氣系數(shù)的增加有效功逐漸降低,壓力升高率持續(xù)減小,平均指示壓力的循環(huán)變動系數(shù)增大,且壓力升高率和平均指示壓力的循環(huán)變動系數(shù)都隨摻氫體積分數(shù)的增加而減小。摻氫體積分數(shù)的增加使熱效率增大,NOX排放增加,未燃HC排放減少。汽油機加氫可以同時降低缸內(nèi)最大壓力的循環(huán)變動系數(shù)和平均指示壓力的循環(huán)變動系數(shù),而且缸內(nèi)最大壓力的循環(huán)變動系數(shù)和平均指示壓力的循環(huán)變動系數(shù)都隨著點火提前角的增加而減小。在加入EGR后,EGR率的增加使NOX排放顯著降低,HC排放升高,瞬時放熱率的峰值降低,其峰值所對應(yīng)的相位也逐漸推遲,平均指示壓力的循環(huán)變動系數(shù)先減小后增大,而摻氫能量分數(shù)對降低平均指示壓力的循環(huán)變動系數(shù)的效果更加明顯。在不使用EGR的條件下,過量空氣系數(shù)是影響扭矩和功率的主要因素。摻氫比、過量空氣系數(shù)和點火提前角對CO排放的影響作用基本相同且都較大。對于CO2排放和HC排放來說都是過量空氣系數(shù)的影響作用最大。而摻氫比是3因素中對NOX排放影響最大的。加入EGR后摻氫比是影響扭矩和功率的主要因素。摻氫比、EGR率和點火提前角對CO排放的影響作用都很大。摻氫比和點火提前角對CO2排放的影響基本相同,但比EGR率的影響略大。對于HC和NOX排放來說都是點火提前角的影響最大,但對于NOX排放EGR率的影響相對于摻氫比和點火提前角有一定的差距。利用BP神經(jīng)網(wǎng)絡(luò)模型對摻氫汽油機性能及排放的分析結(jié)果為:在過量空氣系數(shù)為1.5時,摻氫汽油機的扭矩隨著摻氫比的增加和點火提前角的減小而增大,HC排放量隨著摻氫比的減少和點火提前角的增大而增加,NOX排放量隨著摻氫比的增加和點火提前角的增大而增加。在加入EGR后,摻氫比為25%時點火提前角較小的情況下扭矩隨EGR率的增加而降低,而在點火提前角較大的情況下扭矩隨EGR率的增加呈現(xiàn)出上升的趨勢。HC排放隨著點火提前角和EGR率的增大而增加,NOX排放量隨著點火提前角的減小和EGR率的增加而減少。
[Abstract]:In the background of China's rapid economic development, the number of cars keeps rising year by year, which makes the demand for oil in our country increasing, and it has become an important factor restricting the development of the country as a country with poor oil resources. At the same time, the air pollution caused by automobile exhaust has seriously affected people's life. As a result, the world is working on developing alternative fuels and reducing exhaust emissions. Hydrogen can be used as a substitute fuel and can be added to a gasoline engine to regulate the performance and emissions of gasoline engines. The main advantages of this paper are the direct injection of hydrogen in the cylinder and the injection of gasoline intake, which can effectively avoid the occurrence of tempering. In this paper, the simulation of hydrogen injection process is carried out to determine the best time for hydrogen injection. Then, the spark ignition of hydrogen gasoline mixture fuel is carried out. The effect of hydrogen doping ratio, excess air coefficient, ignition advance angle and EGR rate on the performance and emission of hydrogen doped gasoline engine was analyzed. The grey correlation degree between each influence factor and each performance and emission parameter of the hydrogenated gasoline engine was calculated by the data of the bench test. The influence and influence degree of the parameters of the performance and emission of the hydrogen doped gasoline engine are analyzed by the grey correlation analysis method. Finally, the neural network model is established, and the performance and emission of the hydrogen doped gasoline engine are predicted. The main conclusions are as follows: with the increase of the point fire advance angle, the NOX, HC and CO emissions are all followed. The optimum ignition advance angle decreases with the increase of the volume fraction of hydrogen. With the increase of the excess air coefficient, the effective work gradually decreases, the pressure increase rate decreases continuously, the cyclic variation coefficient of the mean indicator pressure increases, and the pressure rise rate and the average indicator pressure cyclic variation coefficient decrease with the increase of the volume fraction of hydrogen. The increase of the volume fraction of hydrogen makes the thermal efficiency increase, the NOX emission increases and the unburned HC emission decreases. The gasoline engine hydrogenation can simultaneously reduce the cyclic variation coefficient of the maximum pressure in the cylinder and the cyclic variation coefficient of the mean indicator pressure, and the cyclic variation coefficient of the maximum pressure in the cylinder and the cyclic variation coefficient of the mean indicator pressure are all along with the coefficient of variation of the cyclic variation coefficient of the average pressure and the mean pressure. The increase of ignition advance angle decreases. After adding EGR, the increase of EGR rate makes the emission of NOX significantly lower, the emission of HC increases, the peak value of instantaneous exothermic rate decreases, the phase corresponding to the peak value gradually postpones, and the cyclic variation coefficient of the mean indicator pressure decreases first and then increases, and the hydrogen doping energy fraction can reduce the cyclic variation of the mean indicator pressure. The effect of dynamic coefficient is more obvious. Excessive air coefficient is the main factor affecting torque and power without using EGR. The effect of hydrogen ratio, excess air coefficient and ignition advance angle on CO emission is basically the same and larger. For CO2 emission and HC emission, the effect of excess air coefficient is the greatest. The ratio of hydrogen is the most important factor affecting the NOX emission in the 3 factor. The ratio of hydrogen doping is the main factor affecting the torque and power after the addition of EGR. The ratio of hydrogen doping, EGR and ignition advance angle have great influence on the CO emission. The effect of hydrogen doping ratio and ignition advance angle on CO2 emission is basically the same, but it has a little influence on the EGR rate. For HC and NOX emissions are all The effect of ignition advance angle is the greatest, but there is a gap between the effect of NOX emission EGR ratio and ignition advance angle. The analysis results of the performance and emission of hydrogen doped gasoline engine by BP neural network model are as follows: when the excess air coefficient is 1.5, the torsional moment of the hydrogen doped gasoline engine increases with the ratio of hydrogen and ignition advance angle. With the decrease of the hydrogen ratio and the increase of ignition advance angle, the emission of HC increases with the increase of hydrogen doping ratio and the increase of ignition advance angle. When the ratio of hydrogen is added to EGR, the torque of the ignition advance angle decreases with the increase of the ignition advance angle when the ratio of hydrogen is 25%, and the ignition advance angle is larger. The downward torque increases with the increase of EGR rate and increases with the increase of ignition advance angle and EGR rate. The emission of NOX decreases with the decrease of ignition advance angle and the increase of EGR rate.

【學位授予單位】：吉林大學
【學位級別】：博士
【學位授予年份】：2017
【分類號】：TK411

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