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Diesel Emissions and Approaches to their Mitigation
Published in Ozcan Konur, Petrodiesel Fuels, 2021
I. M. Rizwanul Fattah, Hwai Chyuan Ong, T. M. Indra Mahlia, M. Mofijur
Water injection is one of the methods for introducing water to the diesel combustion chamber which helps in reducing the emissions of NOx and particulates simultaneously. There are various ways of injecting water into a combustion chamber, directly into the combustion chamber and by emulsifying fuel (Tauzia et al., 2010). The emulsion is the more practical way of injecting water. The emulsion is created when water is dispersed throughout the fuel, usually in the form of spherical droplets. With the use of emulsions, an improvement in the mixing process is usually observed due to two confirmed phenomena. The first one is added momentum in the jet’s behavior due to water addition (Andrews et al., 1988). The second one is the internal droplet micro-explosions of water induced by the volatility difference between the water and the fuel. This violent disintegration disperses the fine droplets, producing a secondary atomization and consequently enhancing the fuel–air mixing in the combustion chamber (Kadota and Yamasaki, 2002). This increases the premixed combustion duration as well as the ignition delay period, which in turn allows more time for fuel–air mixing, leading to a reduction in PM formation. In addition, water droplet evaporation also reduces peak cycle temperature, which leads to the reduction of NOx emissions.
Application of oxygen enrichment and adiabatic humidification to suction air for reducing exhaust emissions in a gasoline engine
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Murat Kapusuz, Abdülvahap Çakmak, Hakan Özcan
Mingrui et al. (2016) investigated the water injection for low loads in a direct injection gasoline engine. The water was sprayed into the cylinder before fuel injection at 640 °CA (crank angle), with the duration for water injection ending at 650 °CA. The results showed that 15% of water injection by mass to fuel gives the best results. Also, the average effective pressure and efficiency increased while NOX emissions decreased depending on the cooling of certain engine parts. Golzari et al. (2019) investigated the effect of intake port water injection on the efficiency and emissions of a downsized gasoline direct-injection engine. They observed that the indicated efficiency improved by 5–15% with injecting water due to the increasing heat capacity of the charge and cooling effect of injected water, which decreased combustion temperature and pressure. Besides, they found that this led to a reduction in knock sensitivity. In this study, water injection was found useful in reducing NOX emissions by up to 60%. However, HC emissions increased as the injected fuel/water ratio increased. Besides, water injection decreased particle emissions and exhaust gas temperature.
Experimental and Numerical Investigation of Laminar Flame Characteristics of Isooctane/air Mixtures at High Preheating Temperatures and H2O Dilution Ratios
Published in Combustion Science and Technology, 2020
Yejian Qian, Ziyang Yu, Shun Meng, Changfa Tao, Yuan Zhuang, Yang Hua, Chunmei Wang, Jiangquan Wu
New clean combustion technologies for gasoline engines have attracted increasing attention due to the growing number of vehicles and the associated environmental problems. Liquid water injection technology is an effective method to increase the efficiency and reduce the harmful emissions of gasoline and diesel engines. Water (liquid) can be mixed with air for port water injection or be injected into the fuel/air mixture for direct in-cylinder water injection. Because of the larger latent heat of vaporization, the process of liquid water vaporization can produce a cooling effect on the intake air. Moreover, in the combustion process, water vapor acts as a diluent to suppress knocking and reduce NOx emissions (Hoppe et al. 2016; Zhu et al. 2019). It is believed that H2O injection not only helps to control the cylinder temperature evolution but also ensures stoichiometric combustion over the full range of engine operation maps (Falfari et al. 2018).
Enhancing Liquefied Petroleum Gas utilization in Compression-Ignition engine powered with Renewable Fuel under Dual Fuel concept- An Experimental Study
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Shenbagaraj Rajendran, SureshKannan Gurusamy, Vellingiri Sakthivel, Hariharan Natarajan
The authors conducted the experiment in Kirloskar AV-1 single-cylinder engine as it yields a rated output of 3.7 kW with 35 N-m torque at 1,500 rpm constant speed. Table 4 lists out the test engine’s specifications, whereas Figure 4 illustrates the schematic of the test bench. This test bench comprises of performance measurement system, combustion measuring system, emission measuring system, LPG induction system, and water injection system. The performance system includes an eddy current dynamometer, fuel measurement system, and thermocouples for monitoring the temperatures of inlet and exhaust coolants. The engine’s combustion behavior was required from AVL indismart-made combustion analyzer. This acquisition system was used to measure the in-cylinder pressure, heat release rate patterns, ignition delay, and combustion duration. Kistler 6117B type sensor was used to determine the pressure. The emission measurement system comprises of Di-gas analyzer and smoke meter whereas AVL digas 444 analyzer was used to measure HC, CO, and NO emission from the engine exhaust. AVL smoke meter was used to measure smoke in opacity. The uncertainty of emission measurement instruments has listed in Table 5. LPG induction system comprises of LPG cylinder, pressure relief valve, flame trap, and flow meter. The flame trap was used to chunk the misfire at the time of abnormal combustion. The study deployed a Bronkhorst-made digital flowmeter to measure the flow of LPG in a wide range of 0–100 LPM. The water injection system comprises of the water reservoir, flow control valves, water injector, and microcontroller to precisely adjust the start and end injection timings.