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Liquefied Petroleum Gas
Published in Arumugam S. Ramadhas, Alternative Fuels for Transportation, 2016
Mohamed Younes El-Saghir Selim
The nitrogenous oxides (NOx) concentration versus engine load for dual fuel mode and diesel engine is illustrated in Figure 7.13 (Saleh 2008). As the load on the engine was increased, NOx emissions also increased for both dual fuel operation and diesel engine because of an increase in the cylinder combustion temperature and pressure with load. This is considered to be the main reason for the increase in NOx emissions through the Zeldovich mechanism. It would be expected that the fuels with the highest in-cylinder temperature levels would have the highest NOx. Since diesel fuel was a higher combustion chamber temperature as indicated from measured exhaust gas temperature, as shown in Figure 7.13, higher NOx emissions were observed with diesel fuel engine. At full load NOx emissions reached a value of 575 ppm for diesel engine operation and 450 ppm for dual fuel operation. At 25% load, the NOx were 243 ppm and 200 ppm for diesel engine and dual fuel operation, respectively. It can be noticed that the difference of NOx emissions between diesel engine and dual fuel operation is amplified with increase of the engine load, however, the gas fueling fraction increases in dual fuel operation. The main reason is that the propane acts as a diluent in the unburned mixture, increasing the heat capacity of the cylinder charge and reducing effectively the amount of free oxygen that can react with nitrogen to produce NOx.
Experimental and Numerical Investigation of NOx Formation and its Basic Interdependencies on Pulverized Coal Flame Characteristics
Published in Maria da Graça Carvalho, Woodrow A. Fiveland, F. C. Lockwood, Christos Papadopoulos, Combustion Technologies for a Clean Environment, 2021
U. Schnell, M. Kaess, H. Brodbek
In addition to this source of NOx, there is a relatively high portion of NOx formed out of atmospheric nitrogen according to the Zeldovich mechanism in this high-temperature flame. In the first slab at 0.18 m after the burner, the discrepancies between measurement and prediction can be attributed to some deficiencies in the formulation of the pyrolysis reaction. The single one-step reaction does not account for a staged evolution of nitrogeneous intermediates. For that reason the conversion of HCN and ammonia species to NOx is underestimated.
Catalytic Combustion as a Pollution Prevention Technology to Achieve Ultra-Low Emissions in Power Generating Ground-Based Gas Turbine Engines
Published in Nada Assaf-Anid, Hazardous and Industrial Wastes Proceedings of the Thirty-Third Mid-Atlantic Industrial and Hazardous Waste Conference, 2001
Mitchell O. Stokes, Marco J. Castaldi, Lance L. Smith, Hasan Karim, Shahrokh Etemad, William C. Pfefferle
On the other hand, with high temperatures also come drawbacks. For example, the mechanism by which much of the resulting NOx in standard gas turbine combustors - in the form of nitric oxide or NO - is produced, is highly sensitive to temperature. This mechanism, sometimes called “thermal NOx” (or the “Zeldovich mechanism”), begins to rapidly produce NO at temperatures above 1525°C/2780°F.1
Prototype development of a new self-aspirating liquid-fueled microcombustor
Published in Combustion Science and Technology, 2023
Mohammed Asad Khan, Sudarshan Kumar
The exhaust gas temperature remains almost two times higher than the combustor wall temperature. This implies that most of the heat from combustion is lost to the atmosphere through exhaust gases. Since the air entrainment into the combustor is fixed, the fuel flow rate is proportional to the total flow rate and inversely proportional to the residence time in the combustor. As the ethanol flow rate decreases with the pressure head, the residence time of ethanol vapors increases, resulting in an effective kinetic conversion of CO to CO2. At a low fuel flow rate, the fuel-air mixture undergoes lean and complete combustion. Therefore, the CO emission decreases with pressure head, as shown in Figure 9(b). The reduction in CO emissions indicates that the combustion efficiency increases with decreases in pressure head. The CO emissions were observed to vary between 224 and 423 ppm for the operational range of the combustor. In the combustion of fuel that contains no nitrogen, NOx formation dominates at high temperatures via the Zeldovich mechanism. The ethanol diffusion flames have relatively lower flame temperatures (see Figure 7); therefore, no NOx emissions were detected in the exhaust gases. The low temperature of ethanol diffusion flame reflects in terms of partial oxidation of ethanol and leads to considerable CO formation.
Experimental assessment of dibutyl ether on the performance, combustion and emission characteristics of the diesel engine fuelled with Indian Blackberry biodiesel
Published in International Journal of Ambient Energy, 2022
Nitin Kamitkar, Basavaraju Alenahally Ningegowda, V. Dhana Raju
According to the Zeldovich mechanism, NOx emissions are formed because of a reaction between oxygen and nitrogen at elevated temperatures. It is found that more NOx emissions are formed for the IBME blends when compared to the diesel fuel throughout engine operation. This is due to the inherent oxygen of biodiesel and higher cetane number. However, the additions of dibutyl ether to the IBME 20 blend showed a decrease in NOx emissions. The oxides of nitrogen emissions for diesel, IBME10, IBME20, IBME30, IBME 20 DBE 5 and IBME 20 DBE 10 at full load are 1652, 1687, 1698, 1649, 1584 and 1552 ppm, respectively. The NOx emissions are found to be minimum for the diesel and higher for the IBME blends at all load conditions. However, the addition of dibutyl ether revealed a decrement in NOx emissions with an increase in its concentration. The dibutyl ether has a predominant latent heat of vaporisation that brought about lower ignition chamber temperature and consequently lowers NOx emissions. The NOx emissions are reduced by 6.05% and 8.59% for the IBME 20 DBE 10 when compared to diesel and IBME 20 at full load, respectively. Also, the high latent heat of vaporisation of DEE and DBE may reduce the combustion temperature, and hence decreased NOx emissions (Kumari et al. 2020).
Performance, combustion and emission analysis of internal combustion engines fuelled with acetylene – a review
Published in International Journal of Ambient Energy, 2022
Sumit Sharma, Dilip Sharma, Shyam Lal Soni, Digambar Singh, Amit Jhalani
Kannan, Viswabharathy, and Dinesh Kumar (2017) have observed that NOx emission is 1866ppm at maximum output with neat petrol fuel operation. In dual fuel operation with acetylene induction, NOx emission is increased by 17%when compared to baseline petrol operation. According to zeldovich mechanism model, the formation of NOx is attributed to the reaction temperature, reaction duration, and the availability of oxygen. When acetylene is inducted, the increase in NOx may be attributed to the increased peak cycle temperature level because of faster energy release, which is confirmed by increased peak cycle pressure.