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Emission Studies of Direct-Injection Diesel Engines Running on Biodiesel 0 Introduction 2 Test Fuels The impact of diesel engine emissions on human health has received widespread attention worldwide, and various countries have established strict emission regulations accordingly. Research institutions and diesel engine manufacturers are also continuously researching and developing new technologies to control diesel engine emissions. Biodiesel refers to an ester fuel produced by the chemical reaction of fatty acids with alcohols, using plant oils such as rapeseed oil, soybean oil, cottonseed oil, palm oil, oils from wild plants, peanut oil, or their by-products, under the action of a catalyst. Since its properties are similar to those of diesel, it is called biodiesel. Biodiesel has a different chemical structure from vegetable oils; it contains oxygen atoms, which is why it is an oxygen-containing fuel. This paper conducts experimental research and analysis on the emission characteristics of combustion in biodiesel engines. 1 Test instruments The instruments used for the test are shown in Table 1. The diesel engine used in the experiment is the YZ4102OF direct-injection diesel engine, with a rated speed of 3200 r/min. The maximum torque speed is 2200 r/min. During the tests, the original fuel supply system and other parameters of the engine were not altered. The C0, HC, and NOx emissions of the diesel engine were measured using a Horiba MEXA 7200D gas emission analyzer, while its light transmittance smoke density was measured using an AVL439 smoke meter. Table 1 Instruments used in the experiment. Date of receipt: 2005–05–03. Author’s profile: Sun Ping (born 1963), male, from Runié, Jiangsu; professor, Ph.D. (Email: sunping@ujc.edu.cn). The biodiesel used in the experiment was methyl oleate biodiesel produced by Hainan Zhenghe Bioenergy Co., Ltd. The physicochemical properties of this biodiesel were analyzed at Jiangsu University of Technology, and it was compared with 0# diesel. Table 2 shows a comparison of the physicochemical properties of biodiesel and diesel. As can be seen from Table 2, biodiesel and diesel have similar properties; the main difference is that biodiesel contains 10.8% oxygen, while diesel contains no oxygen, and this will have an impact on emissions. 2 Comparison of the physicochemical properties of the two types of fuels 3 Test plan In accordance with GB17961-2001, \"Emission limits and testing methods for exhaust pollutants from compression-ignition engines and vehicles equipped with such engines,\" the engine was operated under the 13 specified operating conditions using diesel and biodiesel. The emission levels of CO, HC, and NOx were measured, as well as the exhaust smoke opacity at each operating condition. Finally, the specific emissions of various pollutants were calculated using the methods specified by the regulations. 4 Test Results and Analysis 4.1 Test Results Figures 1 and 4 show the comparison of emissions of several pollutants under 13 operating conditions when a diesel engine uses either diesel or biodiesel as fuel. Table 3. 209.. VIP Information http://www.cqvip.com March 2006, Agricultural Mechanization Research, Issue 3: A comparison of the specific emissions of several pollutants. Pedicel: . ； . J J J J}} Kuangbao Star Braid J. Figure 1: Comparison of emissions under condition 13 between the original engine and biodiesel. 400 – I}l II]12. Limit! I500 1000 Xiang50o 0. Figure 2: Comparison of H0 emissions under condition 13 between the original engine and biodiesel. f r–] L. Curve: 1 2 3 4 5 6 7 8 9 10 11 12 13. Condition. Figure 3: Comparison of NOx emissions under condition 13 between the original engine and biodiesel. Weiyun o.zI} One day. Mouth. By one JL 1.}【 1J .l『1—.L field J. ■Lan⋯Zhu— { l 2 3 4 5 6 7 8 9 10 l1 12 13 Operating conditions: Circle 4 – Comparison of smoke emissions between the original engine and one using biodiesel under condition 13; Circle 3 – Comparison of emission levels between the original engine and one using biodiesel under condition 13. Emissions in g/kW·h: CO, HC, NOx, PH. 4.2 Analysis of emission results under condition 13: As can be seen from Figure i-4, biodiesel reduces the emissions of CO, HC, and smoke from diesel engines, while its emissions of NOx increase. This is due to the differences in their physicochemical properties; in particular, biodiesel contains oxygen, as explained in detail below. 4.2.1 CO Emissions As can be seen from Figure i, regarding CO emissions, the original machine has the highest emission levels under conditions 8 and 9 ； And the reduction in emissions from biodiesel under these two operating conditions is also the most significant. This is because these two operating conditions involve high load at rated speed; the high speed results in large intake swirls, leading to a lower charge coefficient ； Due to the high load and large amount of fuel injection, severe local oxygen deficiency occurs, leading to increased incomplete combustion of the fuel and higher CO emissions. Under most operating conditions, biodiesel can reduce CO emissions. The reduction in CO emissions is mainly due to the fact that biodiesel is an oxygen-containing fuel, which lowers the overall air-fuel ratio. Studies have shown that the oxygen present in biodiesel has a much greater impact on combustion and emissions than oxygen of the same mass in air; this increases the degree of complete combustion of the fuel in the rich fuel regions, thereby reducing the formation of CO ； Secondly, biodiesel has a higher cetane number than diesel; fuels with a high cetane number have better ignition properties, which facilitates the starting of diesel engines and ensures that more fuel burns completely, thereby reducing the production of CO. 4.2.2 HC Emissions As can be seen from Figure 2, the differences in HC emissions under various conditions are not very significant ； Biodeiesel had lower HC emissions under each T condition compared to the original engine, with a reduction rate of 7.7% to 52.5%. From Table 3, the specific discharge decreases to 40.2%. It can be seen that biodiesel is quite effective in reducing HC emissions. There are two possible explanations for this phenomenon: one is that fatty acid esters contain oxygen atoms in their molecules. But regular diesel doesn’t have it. The additional oxygen in the fuel means that it will burn more cleanly, which will allow more particles and unburned HC to burn before leaving the combustion chamber. Second, the carbon chain of biodiesel esters is relatively long. Methyl oleate biodiesel (C18:2) is composed of HC chains with a carbon chain length of 18 carbon atoms. Long-chain HC generally reduces diesel engine emissions. 4.2.3 NOx Emissions As can be seen from Figure 3, in most cases… http://www.cqvip.com March 2006 Agricultural Mechanization Research, Issue 3 4.3 Comparison of Emission Ratios The data in Table 3 show this. The original vehicle’s CO emissions are below the Euro 2 standard, its Hc and PM emissions are below the Euro 1 standard, while its NOx emissions are close to the Euro 1 limit. When used as a fuel, biodiesel results in cO and Hc emissions that are below the Euro 2 emission limits; these emissions are reduced by 34.6% and 40.2%, respectively, while the P~I emission is reduced by 19.6% ； However, N0x increased by 6.63% compared to the emission level, reaching 8.576 g/kW·h. Biodiesel is an oxygen-containing fuel. And F1 has a higher cetane number than diesel, so it burns more rapidly and completely; this is the main reason for the reduction in HC, CO, and PM emissions as well as the increase in NOx. and 19.6%. N0x is 6.63% higher than diesel.