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The chemical reactions leading to the destruction of NO and CO in the engine combustion gases are temperature dependent and it has been observed that they change over from 'shifting' equilibrium to 'frozen' equilibrium as the temperature drops during the expansion phase. Application of reaction rate theories to the prediction of exhaust emissions is complex and can at best be an approximation owing to uncertainties of the engine combustion reaction mechanism, the assumed rate constants and the estimated combustion temperatures. An attempt was made to correlate the computed equilibrium concentrations during the expansion phase to the measured emission levels of NO and CO to estimate the temperatures at which nonequilibrium effects become apparent. Comparison of the measured emission levels from a single cylinder spark ignition engine with the computed equilibrium concentrations for several engine operating conditions has shown that the concentration of NO freezes near its peak equilibrium value, whereas the destruction of CO continues during the subsequent expansion phase until the temperature has dropped to an effective 'frozen equilibrium temperature' at which the computed equilibrium CO corresponds to the measured level in the exhaust. This temperature is dependent on the time rate of expansion and was determined to be 1250°K at 600 rpm and 1300°K at 900 rpm for the steady state operating conditions considered in the present series of tests.; An attempt has been made to correlate the computed equilibrium concentrations during the expansion phase to the measured emission levels of NO and CO to estimate the temperatures at which nonequilibrium effects become apparent. Comparison of the measured emission levels from a single cylinder spark ignition engine with the computed equilibrium concentrations for several engine operating conditions has shown that the concentration of NO freezes near its peak equilibrium value, whereas the destruction of CO continues during the subsequent expansion phase until the temperature has fallen down to an effective 'frozen-equilibrium temperature' at which the computed equilibrium CO corresponds to the measured level in the exhaust.
(Exhaust emission characteristics correlated to a chemically equilibrating gaseous system in an SI engine) Samaga, B.S.
1976
Electrochemical corrosion study of Mg-Al-Zn-Mn alloy in aqueous ethylene glycol containing chloride ions
(Elsevier Editora Ltda, 2017) Medhashree, H.; Nityananda Shetty, A.N.
Nowadays most of the automobiles use magnesium alloys in the components of the engine coolant systems. These engine coolants used are mainly composed of aqueous ethylene glycol along with some inhibitors. Generally the engine coolants are contaminated by environmental anions like chlorides, which would enhance the rate of corrosion of the alloys used in the coolant system. In the present study, the corrosion behavior of Mg-Al-Zn-Mn alloy in 30% (v/v) aqueous ethylene glycol containing chloride anions at neutral pH was investigated. Electrochemical techniques, such as potentiodynamic polarization method, cyclic polarization and electrochemical impedance spectroscopy (EIS) were used to study the corrosion behavior of Mg-Al-Zn-Mn alloy. The surface morphology, microstructure and surface composition of the alloy were studied by using the scanning electron microscopy (SEM), optical microscopy and energy dispersion X-ray (EDX) analysis, respectively. Electrochemical investigations show that the rate of corrosion increases with the increase in chloride ion concentration and also with the increase in medium temperature. © 2016 Brazilian Metallurgical, Materials and Mining Association.
Influence of Magneto-combustion on regulated emissions of an automotive engine under variable speed operation
(MechAero Found. for Techn. Res. and Educ. Excellence office@mechaero.org, 2020) Oommen, L.P.; Kumar, G.N.
The present study investigates the influence of magneto-combustion on the macro pollutants emitted from a multi point fuel injection (MPFI) automotive engine. The regulated emissions of an auto engine include carbon monoxide, un-burnt hydrocarbon (UBHC)and oxides of nitrogen (NOx) which are the by-products of internal combustion of the hydrocarbon fuel used. Depending upon the physiochemical characteristics of pollutants and their concentrations, these pollutants result in numerous physical ailments and mortality. Magneto-combustion is an under investigated technology which effectively reduces the emission of toxic vehicular exhaust. The exposure to an external magnetic field realigns the hydrocarbon structure and alters its combustion properties. The tests conducted on a Maruthi Zen MPFI engine under two different patterns of magnetisation resulted in a maximum reduction of carbon monoxide by 23.97%, UBHC by 13.1% and NOx by 5.23%, thereby reduced the cumulative negative impact on the environment. © 2020. MechAero Foundation for Technical Research & Education Excellence.
Impact of 1-Hexanol/diesel blends on combustion, performance and emission characteristics of CRDI CI mini truck engine under the influence of EGR
(Elsevier Ltd, 2020) Santhosh, K.; Kumar, G.N.
Biofuels are the most promising sustainable and renewable alternative to diesel fuel. In the present renewable energy world, alcohols are gaining prime importance due to their nature of production and fuel properties. The present work aims to investigate the impact of 1-Hexanol and exhaust gas recirculation (10% and 20%) on engine characteristics of the common rail direct injection compression ignition engine. The experiment is carried out on a bench engine. The fraction of 1-Hexanol is varied from 10% to 40% in a step of 10% by volume. The results demonstrate that the use of 1-Hexanol/diesel blends lowers the cylinder pressure and mean gas temperature, which is 4.25% and 1.88% lower at 60% load for 40% 1-Hexanol compared to neat diesel fuel operation. The combustion duration is increased by 2.66?CA for 40% 1-Hexanol at 60% load compared to neat diesel fuel. However, an improvement in net heat release rate is noted which is 13.95% higher at 60% load for 40% 1-Hexanol, this increment is due to prolonged ignition delay. With the use of 1-Hexanol in the engine, there is a drastic reduction in nitrogen oxide emission is observed, this is the greatest impact of 1-Hexanol. However, a slight increment in the hydrocarbon and carbon monoxide emission is also noted due to poor fuel properties like lower cetane number, higher viscosity and higher latent heat of evaporation of 1-Hexanol. Compared to all other blends in the test 10% 1-Hexanol shows comparable results with pure diesel fuel, which is only 2.37% lower in brake thermal efficiency, 3.6% higher in brake specific fuel consumption, 17.55% lower in nitrogen oxide emission, 18.18% higher in hydrocarbon and 33.33% higher in carbon monoxide emission is noted. The exhaust gas recirculation helps in reducing the NOx emission, 40% 1-Hexanol is less sensitive to exhaust gas recirculation. Up to 40% of 1-Hexanol can be used in the CI engine without any modification. It is concluded that 1-Hexanol is a sustainable renewable biofuel due to the reason that even though the use of 1-Hexanol lowers the performance which helps in reducing the NOx emission greatly; the performance can be improved by modifying the engine parameters. © 2020 Elsevier Ltd
Design and development of an experimental setup for nanofinishing of exhaust valves using magnetorheological finishing to enhance functional performance
(Springer-Verlag Italia s.r.l., 2025) Sharma, K.; Singh, V.K.; Singh Rajput, A.S.; Das, M.
Exhaust valves in high-performance and racing engines require ultra-smooth surfaces to improve durability and operational efficiency. This study investigates the application of Magnetorheological (MR) polishing for finishing exhaust valve seats. MR fluid, consisting of micron-sized magnetic particles suspended in a carrier liquid, forms a semi-solid structure under a magnetic field, enabling precise surface finishing. An in-house experimental setup was developed, and various magnet configurations were tested to optimize the polishing zone. Computational investigations were conducted to analyze magnetic field distribution for 2-bar, 3-bar, 4-bar, and 5-bar magnet systems, with results validated using a Gauss-meter. Unlike prior MR polishing studies that focused mainly on optical or biomedical components, our work emphasizes automotive engine applications and demonstrates the optimization of a 4-magnet system to achieve uniform magnetic field distribution. The novelty lies in developing a cost-effective, adaptable, and reproducible MR polishing arrangement tailored for curved valve geometries, while addressing reproducibility through detailed experimental parameters. The primary objective was to optimize process parameters for MR polishing. Under optimal conditions—spindle speed of 750 RPM, stand-off distance of 1.5 mm, and polishing time of 17.5 min—the surface roughness (Ra) improved significantly from 0.613 ?m to 0.115 ?m. Measurements were performed using a 3D profilometer. Further surface characterization via Atomic Force Microscopy (AFM) showed a reduction in surface asperities, while Field Emission Scanning Electron Microscopy (FE-SEM) revealed fewer surface scratches. These results confirm the potential of MR polishing as an effective technique for enhancing the surface finish of critical engine components. © The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature 2025.

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