Development of an Exhaust Gas Recirculation Distribution Prediction Method Using Three-Dimensional Flow Analysis and Its Application

A multidimensional computational fluid dynamics (CFD) method has been used to improve the exhaust gas recirculation (EGR) distribution in the intake manifold. Since gas flow in the intake system is affected by intake pulsation caused by the gas exchange process, a pulsation flow simulation is used. A one-dimensional gas exchange calculation is combined with three-dimensional intake gas flow calculation to simulate pulsation flow. This pulsation flow simulation makes it possible to predict the EGR distribution. The gas flow in the intake system was analyzed in detail. It was found that a reverse flow region formed downstream of the throttle valve. The size and shape of the reverse flow region greatly depend on the engine operating conditions. With a conventional EGR system, it is difficult to distribute EGR uniformly under various engine operating conditions. A new EGR system that uses a spiral flow to mix the fresh air and EGR gas has been developed to obtain a uniform EGR distribution. As a result of adopting this system, a uniform EGR distribution is obtained regardless of the engine operating conditions. This spiral flow EGR system was applied to a low-emission vehicle (LEV) put on the Japanese market.

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Development of an EGR Distribution Prediction Method Using Three-Dimensional Flow Analysis and its Application

Volume 3: Engine Systems: Lubrication, Components, Exhaust and Boosting, System Design and Simulation ◽

10.1115/2001-ice-425 ◽

2001 ◽

Author(s):

Koudai Yoshizawa ◽

Kouji Mori ◽

Yutaka Matayoshi ◽

Shuji Kimura

Keyword(s):

Gas Exchange ◽

Gas Flow ◽

Reverse Flow ◽

Three Dimensional ◽

Flow Simulation ◽

Flow Region ◽

Operating Conditions ◽

Intake Manifold ◽

Spiral Flow ◽

Intake System

Abstract A multidimensional computational fluid dynamics (CED) method has been used to improve the exhaust gas recirculation (EGR) distribution in the intake manifold. Since gas flow in the intake system is affected by intake pulsation caused by the gas exchange process, a pulsation flow simulation is used. A one-dimensional gas exchange calculation is combined with three-dimensional intake gas flow to simulate pulsation flow. This pulsation flow simulation makes it possible to predict the EGR distribution. The gas flow in the intake system was analyzed in detail. It was found that a reverse flow region formed downstream of the throttle valve. The size and shape of the reverse flow region greatly depend on the engine operating conditions. With a conventional EGR system, it is difficult to distribute EGR uniformly under various engine operating conditions. A new EGR system that uses a spiral flow to mix the fresh air and EGR gas has been developed to obtain a uniform EGR distribution. As a result of adopting this system, a uniform EGR distribution is obtained regardless of the engine operating conditions. This spiral flow EGR system was applied to a low-emission vehicle (LEV) put on the Japanese market.

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Condensation Analysis of Exhaust Gas Recirculation System for Heavy-Duty Trucks

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4004745 ◽

2011 ◽

Vol 3 (4) ◽

Cited By ~ 7

Author(s):

Bing-Jian Yang ◽

Shaolin Mao ◽

Orhan Altin ◽

Zhi-Gang Feng ◽

Efstathios E. Michaelides

Keyword(s):

Heat Exchanger ◽

Cfd Simulation ◽

Three Dimensional ◽

Exhaust Gas Recirculation ◽

Operating Conditions ◽

Condensation Process ◽

Transfer Model ◽

Exhaust Gas ◽

Heavy Duty ◽

Gas Recirculation

The exhaust gas recirculation (EGR) system has been widely used in the automotive and heavy-duty trucks to reduce NOx, SOx, and other controlled emissions. A liquid-cooled or air-cooled heat exchanger is the main constituent of the EGR system. The heat exchanger decreases the temperature of the exhaust gases mixture that flows through the EGR channels and the lower temperatures reduce the content of the controlled gas emissions. Condensation of water vapor is an undesirable by-product of the EGR systems because, in combination with the emission gases, it forms the corrosive sulfuric and nitric acids. The U.S. EPA has suggested that engine makers should turn off their EGR systems periodically to avoid the formation of the corrosive sulfuric and nitric acids. In order to accurately predict the corrosion process, a condensation model has been developed to investigate the rates of formation and diffusion of nitric acid and sulfuric acid to the cold tube surface. A three-dimensional computational fluid dynamics (CFD) simulation has been conducted for a typical EGR cooler during normal operating conditions of Tier 4 heavy-duty trucks. A lumped, 1D heat and mass transfer model has also been developed to study the most important physical aspects of the condensation process. The CFD and the analytical results of the rate of condensation and local fluid properties are an important and inexpensive complement to more expensive experimental measurements and testing. Such models may be used to improve the design and to optimize the operating conditions of the EGR systems and may become valuable tools in the design and manufacturing of the next generation of EGR systems for diesel engines. The model developed is general and the techniques and numerical results of this study may be extended to engine reliability, corrosion reduction, and damage prevention of other industrial engines.

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Three-dimensional simulation analysis of the effect of hydrous ethanol and exhaust gas recirculation on gasoline direct injection engine combustion and emissions

Journal of Energy Resources Technology ◽

10.1115/1.4052861 ◽

2021 ◽

pp. 1-22

Author(s):

Xiuyong Shi ◽

Yixiao Jiang ◽

Qiwei Wang ◽

Weiwei Qian ◽

Rong Huang ◽

...

Keyword(s):

Aqueous Ethanol ◽

Direct Injection ◽

Three Dimensional ◽

Exhaust Gas Recirculation ◽

Exhaust Gas ◽

Engine Combustion ◽

Carbon Soot ◽

Dimensional Simulation ◽

Gas Recirculation ◽

Hydrous Ethanol

Abstract To analyze the influence of hydrous ethanol on the performance of the direct injection engine, the three-dimensional simulation is carried out by using CONVERGE software coupled with the combustion mechanism of hydrous ethanol gasoline and the soot model. The combustion and soot generation characteristics of a direct injection gasoline engine burning aqueous ethanol gasoline using exhaust gas recirculation (EGR) technology were investigated. It was found that the increase of the blending ratio of the hydrous ethanol can accelerate the flame propagation speed, shorten the combustion duration, and improve the combustion isovolume. The nucleation and growth of soot are jointly controlled by PAHs and the small molecular components such as C2H2. The oxygen content properties and high reactive OH of the aqueous ethanol-containing gasoline inhibit soot formation. Compared with pure gasoline, the carbon soot precursor mass was reduced by 60%, 54.5%, 73.3% and 52.4% for 20% anhydrous ethanol blended with gasoline, A1, A2, A3 and A4, respectively, and the carbon soot mass was reduced by 63.6% and the carbon soot volume density was reduced by 40%. The introduction of EGR exhaust reduces the burning rate and leads to an increase in the production of Carbon monoxide, hydrocarbon, and soot. However, the combination of EGR with aqueous ethanol gasoline can significantly improve the engine combustion environment, significantly reducing soot and PAHs concentrations. The impact of EGR also includes the ability to reduce combustion chamber temperatures and reduce NOx emissions from aqueous ethanol gasoline by 75%.

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Learning reference governor for cycle-to-cycle combustion control with misfire avoidance in spark-ignition engines at high exhaust gas recirculation–diluted conditions

International Journal of Engine Research ◽

10.1177/1468087420929109 ◽

2020 ◽

Vol 21 (10) ◽

pp. 1819-1834

Author(s):

Bryan P Maldonado ◽

Nan Li ◽

Ilya Kolmanovsky ◽

Anna G Stefanopoulou

Keyword(s):

Combustion Process ◽

Exhaust Gas Recirculation ◽

Operating Conditions ◽

Intake Manifold ◽

Exhaust Gas ◽

Model Free ◽

Recirculation Rate ◽

Valve Position ◽

Gas Recirculation ◽

Reference Governor

Cycle-to-cycle feedback control is employed to achieve optimal combustion phasing while maintaining high levels of exhaust gas recirculation by adjusting the spark advance and the exhaust gas recirculation valve position. The control development is based on a control-oriented model that captures the effects of throttle position, exhaust gas recirculation valve position, and spark timing on the combustion phasing. Under the assumption that in-cylinder pressure information is available, an adaptive extended Kalman filter approach is used to estimate the exhaust gas recirculation rate into the intake manifold based on combustion phasing measurements. The estimation algorithm is adaptive since the cycle-to-cycle combustion variability (output covariance) is not known a priori and changes with operating conditions. A linear quadratic regulator controller is designed to maintain optimal combustion phasing while maximizing exhaust gas recirculation levels during load transients coming from throttle tip-in and tip-out commands from the driver. During throttle tip-outs, however, a combination of a high exhaust gas recirculation rate and an overly advanced spark, product of the dynamic response of the system, generates a sequence of misfire events. In this work, an explicit reference governor is used as an add-on scheme to the closed-loop system in order to avoid the violation of the misfire limit. The reference governor is enhanced with model-free learning which enables it to avoid misfires after a learning phase. Experimental results are reported which illustrate the potential of the proposed control strategy for achieving an optimal combustion process during highly diluted conditions for improving fuel efficiency.

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Cyclic NO2:NOx ratio from a diesel engine undergoing transient load steps

International Journal of Engine Research ◽

10.1177/1468087419833202 ◽

2019 ◽

Vol 22 (1) ◽

pp. 284-294 ◽

Cited By ~ 5

Author(s):

FCP Leach ◽

MH Davy ◽

MS Peckham

Keyword(s):

Diesel Engine ◽

High Speed ◽

Exhaust Gas Recirculation ◽

Operating Conditions ◽

Formation Mechanisms ◽

Exhaust Gas ◽

Work Cycle ◽

Wide Range ◽

Gas Recirculation ◽

Aftertreatment Systems

As the control of real driving emissions continues to increase in importance, the importance of understanding emission formation mechanisms during engine transients similarly increases. Knowledge of the NO2/NOx ratio emitted from a diesel engine is necessary, particularly for ensuring optimum performance of NOx aftertreatment systems. In this work, cycle-to-cycle NO and NOx emissions have been measured using a Cambustion CLD500, and the cyclic NO2/NOx ratio calculated as a high-speed light-duty diesel engine undergoes transient steps in load, while all other engine parameters are held constant across a wide range of operating conditions with and without exhaust gas recirculation. The results show that changes in NO and NOx, and hence NO2/NOx ratio, are instantaneous upon a step change in engine load. NO2/NOx ratios have been observed in line with previously reported results, although at the lightest engine loads and at high levels of exhaust gas recirculation, higher levels of NO2 than have been previously reported in the literature are observed.

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Optimization of a diesel engine calibration for operating with a residual glycerol-derived biofuel

International Journal of Engine Research ◽

10.1177/1468087419891535 ◽

2019 ◽

pp. 146808741989153 ◽

Cited By ~ 2

Author(s):

Magín Lapuerta ◽

Ángel Ramos ◽

Sara Rubio ◽

Carles Estévez

Keyword(s):

Particulate Matter ◽

Fatty Acid ◽

Diesel Fuel ◽

Exhaust Gas Recirculation ◽

Operating Conditions ◽

Transport Sector ◽

Exhaust Gas ◽

Engine Calibration ◽

Particulate Matter Emissions ◽

Gas Recirculation

The new European directive for the promotion of renewable energy mandates an increase in the share of advanced and waste-based biofuels in the transport sector. In this study, an advanced glycerol-derived biofuel was used as a component of a ternary blend, denoted as o·bio®. This blend included 27.4 %v/v of fatty acid glycerol formal ester, 69.6 %v/v of fatty acid methyl ester and 3 %v/v of acetals obtained as a by-product of the fatty acid glycerol formal ester production process (which were proved to improve cold-flow properties). Finally, o·bio® was blended with diesel fuel at a content of 20 %v/v. Two operating conditions based on usual driving modes were selected, where the engine calibration could be re-optimized after the change of fuel, corresponding to vehicle velocities of 50 and 70 km/h. Since the main effect of the blend used is to reduce particulate matter emissions, exhaust gas recirculation was increased and injection was delayed, so that the initial benefits in particulate matter emissions could be re-distributed into benefits in both particulate matter and nitrogen oxides (NOx) emissions. From a combined analysis of the particulate matter–NOx trade-off and trying to limit the negative effect of delaying injection on fuel consumption, the final proposal was to set an additional 6% exhaust gas recirculation at 50 km/h and an additional 3% exhaust gas recirculation at 70 km/h, while delaying injection 2 °CA after top dead center at both vehicle operating conditions with respect to the original calibration. The use of the blend along with the optimization of the engine calibration is expected to reduce particulate matter and NOx emissions by around 50% with a vehicle speed condition of 50 km/h and to reduce particulate matter and NOx emissions by around 30% and 40% at 70 km/h with respect to diesel fuel emissions.

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Enhancement of the combustion process in dual-fuel engines at part loads using exhaust gas recirculation

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1243/09544070jauto389 ◽

2007 ◽

Vol 221 (7) ◽

pp. 877-888 ◽

Cited By ~ 10

Author(s):

V Pirouzpanah ◽

R Khoshbakhti Saray

Keyword(s):

Chemical Kinetics ◽

Combustion Process ◽

Exhaust Gas Recirculation ◽

Operating Conditions ◽

Combustion Model ◽

Dual Fuel ◽

Exhaust Gas ◽

Performance And Emission ◽

Dual Fuel Engines ◽

Gas Recirculation

Dual-fuel engines at part loads inevitably suffer from lower thermal efficiency and higher carbon monoxide and unburned fuel emission. The present work was carried out to investigate the combustion characteristics of a dual-fuel (diesel-gas) engine at part loads, using a single-zone combustion model with detailed chemical kinetics for combustion of natural gas fuel. The authors have developed software in which the pilot fuel is considered as a subsidiary zone and a heat source derived from two superimposedWiebe combustion functions to account for its contribution to ignition of the gaseous fuel and the rest of the total released energy. The chemical kinetics mechanism consists of 112 reactions with 34 species. This quasi-two-zone combustion model is able to establish the development of the combustion process with time and the associated important operating parameters, such as pressure, temperature, heat release rate (HRR), and species concentration. Therefore, this paper describes an attempt to investigate the combustion phenomenon at part loads and using hot exhaust gas recirculation (EGR) to improve the above-mentioned drawbacks and problems. By employing this technique, it is found that lower percentages of EGR and allowance for its thermal and radical effects have a positive influence on performance and emission parameters of dual-fuel engines at part loads. Predicted values show good agreement with corresponding experimental values under special engine operating conditions (quarter-load, 1400 r/min). Implications are discussed in detail.

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Effects of Exhaust Gas Recirculation on Particulate Morphology from a Diesel Engine

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.664.926 ◽

2013 ◽

Vol 664 ◽

pp. 926-930

Author(s):

Wei Zhang ◽

Xiao Dong Wang ◽

Rui Sun ◽

Jian Wei Sun ◽

Wei Han

Keyword(s):

Particle Size ◽

Diesel Engine ◽

Primary Particle ◽

Morphological Characteristics ◽

Exhaust Gas Recirculation ◽

Operating Conditions ◽

Injection System ◽

Exhaust Gas ◽

Aggregate Particle ◽

Gas Recirculation

The effects of EGR operating mode on particulate morphology were investigated for a 5.79-liter diesel engine which was equipped with a turbocharged and inter-cooled air induction system, a common-rail direct fuel injection system, and an EGR system. Morphological characteristics, such as primary particle size, number concentration and aggregate particle size were investigated by a transmission electron microscope (TEM) analysis and a electrical low pressure impactor (ELPI) under engine operating conditions of 0.41 in fuel/air ratio at different exhaust gas recirculation (EGR) rate from 0～35%. The experimental results indicated that primary particle were in the range of 17.05nm～18.34nm, which increased with increased EGR rate. As EGR rate increased, aggregate particle size were measured in a narrow range from 120nm to 170nm.

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