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

2019 ◽  
Vol 22 (1) ◽  
pp. 284-294 ◽  
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.

Experimental Study on Effects of Nozzle Hole Geometry on Achieving Low Diesel Engine Emissions

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
Prashanth K. Karra ◽  
Song-Charng Kong
Keyword(s):  
Diesel Engine ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Injection System ◽  
Exhaust Gas ◽  
Convergent Nozzle ◽  
Wide Range ◽  
Soot Emissions ◽  
Gas Recirculation ◽  
Injection Pressures

Three injectors with different nozzle geometries were tested in a multicylinder diesel engine with a high-pressure common-rail injection system. Various injection pressures were tested along with exhaust gas recirculation to achieve low NOx and soot emissions. The injectors used in the study included a six-hole nozzle, a ten-hole nozzle, and a six-hole convergent nozzle with a K-factor of 3. All three injectors had the same flow numbers. All three injectors tested were effective in reducing NOx and soot emissions at appropriate conditions. It was found that low temperature combustion can be achieved by using high levels of exhaust gas recirculation with late injection timings. High injection pressures significantly reduced soot emissions at conventional injection timings. The effect of injection pressure was not significant at retarded injection timings, i.e., 5 ATDC. The convergent nozzle was found to produce higher soot emissions compared with the straight-hole nozzle under the same injection conditions. Effects of the convergent nozzle on NOx emissions and fuel consumption were not significant. The small nozzle size in the ten-hole injector can generate smaller fuel drops and lead to better atomization. The ten-hole injector appeared to have better air utilization and resulted in significant reductions in NOx and soot emissions over a wide range of operating conditions.

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

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.

The effects of carbon dioxide in exhaust gas recirculation on diesel engine emissions

1998 ◽  
Vol 212 (1) ◽  
pp. 25-42 ◽  
Author(s):  
N Ladommatos ◽  
S M Adelhalim ◽  
H Zhao ◽  
Z Hu
Keyword(s):  
Carbon Dioxide ◽  
Diesel Engine ◽  
High Speed ◽  
Combustion Process ◽  
Dilution Effect ◽  
Exhaust Gas Recirculation ◽  
Chemical Effect ◽  
Particulate Emissions ◽  
Exhaust Gas ◽  
Gas Recirculation

The investigation was conducted on a high-speed direct injection diesel engine and was concerned with the effects of exhaust gas recirculation (EGR) on diesel engine combustion and emissions. In particular, the effects of carbon dioxide (CO2), a principal constituent of EGR, on combustion and emissions were analysed and quantified experimentally. The use of CO2 to displace oxygen (O2) in the inlet air resulted in: reduction in the O2 supplied to the engine (dilution effect), increased inlet charge thermal capacity (thermal effect), and, potentially, participation of the CO2 in the combustion process (chemical effect). In a separate series of tests the temperature of the engine inlet charge was raised gradually in order to simulate the effect of mixing hot EGR with engine inlet air. Finally, tests were carried out during which the CO2 added to the engine air flow increased the charge mass flowrate to the engine, rather than displacing some of the O2 in the inlet air. It was found that when CO2 displaced O2 in the inlet charge, both the chemical and thermal effects on exhaust emissions were small. However, the dilution effect was substantial, and resulted in very large reductions in exhaust oxides of nitrogen (NO x) at the expense of higher particulate and unburned hydrocarbon (uHC) emissions. Higher inlet charge temperature increased exhaust NO x and particulate emissions, but reduced uHC emissions. Finally, when CO2 was additional to the inlet air charge (rather than displacing O2), large reductions in NOx were recorded with little increase in particulate emissions.

Nonlinear Compensators of Exhaust Gas Recirculation and Variable Geometry Turbocharger Systems using Air Path Models for a CRDI Diesel Engine

2013 ◽  
Vol 136 (4) ◽  
Author(s):  
Yeongseop Park ◽  
Inseok Park ◽  
Joowon Lee ◽  
Kyunghan Min ◽  
Myoungho Sunwoo
Keyword(s):  
Diesel Engine ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Variable Geometry ◽  
Variable Geometry Turbocharger ◽  
Model Based ◽  
Path Models ◽  
Gas Recirculation ◽  
Feedforward Compensators

This paper investigates the design of model-based feedforward compensators for exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems using air path models for a common-rail direct injection (CRDI) diesel engine to cope with the nonlinear control problem. The model-based feedforward compensators generate set-positions of the EGR valve and the VGT vane to track the desired mass air flow (MAF) and manifold absolute pressure (MAP) with consideration of the current engine operating conditions. In the best case, the rising time to reach 90% of the MAF set-point was reduced by 69.8% compared with the look-up table based feedforward compensators.

scholarly journals Characterisation and optimisation of a real-time diesel engine model

2017 ◽  
Vol 231 (14) ◽  
pp. 1913-1934 ◽  
Author(s):  
Peter G Dowell ◽  
Sam Akehurst ◽  
Richard D Burke
Keyword(s):  
Diesel Engine ◽  
Real Time ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Step Size ◽  
Time Model ◽  
Crank Angle ◽  
Run Time ◽  
Gas Recirculation

Accurate real-time engine models are an essential step to allow the development of control algorithms in parallel to the development of engine hardware using hardware-in-the-loop applications. A physics-based model of the engine high-pressure air path and combustion chamber is presented. The model was parameterised using data from a small set of carefully selected operating conditions for a 2.0 l diesel engine. The model was subsequently validated over the complete engine operating map with exhaust gas recirculation and without exhaust gas recirculation. A high level of fit was achieved with R2 values above 0.94 for the mean effective pressure and above 0.99 for the air flow rate. The model run time was then reduced for real-time application by using forward differencing and single-precision floating-point numbers and by calculating the in-cylinder prediction for only a single cylinder. A further improvement of 25% in the run time was achieved by improving the submodels, including the strategic use of one-dimensional and two-dimensional look-up tables with optimised resolution. The model exceeds the performance of similar models in the literature, achieving a crank angle resolution of 0.5° at 4000 r/min. This simulation step size still yields good accuracy in comparison with a crank angle resolution of 0.1° and was validated against the experimental results from a New European Driving Cycle. The real-time model allows the development of control strategies before the engine hardware is available, meaning that more time can be spent to ensure that the engine can meet the performance and the emissions requirements over its full operating range.

Effects of Nozzle Hole Arrangement on Diesel Engine Emissions

2009 ◽  
Author(s):  
Prashanth K. Karra ◽  
Song-Charng Kong
Keyword(s):  
Injection Pressure ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Low Temperature Combustion ◽  
Convergent Nozzle ◽  
Wide Range ◽  
Soot Emissions ◽  
Gas Recirculation ◽  
Injection Pressures

Various diesel injectors and injection pressures were tested along with exhaust gas recirculation to achieve low NOx and soot emissions. The injectors used in the study included a 6-hole nozzle, a 10-hole nozzle, and a 6-hole convergent nozzle with a K-factor of 3. All three injectors had the same flow numbers and they were effective in reducing NOx and soot emissions at appropriate conditions. It was found that low temperature combustion can be achieved by using high levels of exhaust gas recirculation with late injection timings. High injection pressures significantly reduced soot emissions at conventional injection timings. The effect of injection pressure was not significant at retarded injection timings, i.e., 5 ATDC. The convergent nozzle was found to produce higher soot emissions and its effects on NOx emissions and fuel consumption were not significant. The small nozzle size in the 10-hole injector can generate smaller fuel drops and lead to better atomization. The 10-hole injector appeared to have better air utilization and resulted in significant reductions in NOx and soot emissions over a wide range of operating conditions.

scholarly journals Experimental study on diesel engine exhaust gas recirculation performance and optimum exhaust gas recirculation rate determination method

2019 ◽  
Vol 6 (6) ◽  
pp. 181907 ◽  
Author(s):  
Xiang-huan Zu ◽  
Chuan-lei Yang ◽  
He-Chun Wang ◽  
Yin-yan Wang
Keyword(s):  
Decision Making ◽  
High Pressure ◽  
Diesel Engine ◽  
High Speed ◽  
Performance Test ◽  
Exhaust Gas Recirculation ◽  
Venturi Tube ◽  
Pressure Curve ◽  
Exhaust Gas ◽  
Gas Recirculation

In order to study the exhaust gas recirculation (EGR) performance of marine diesel engines, a venturi high-pressure EGR device was established to overcome the exhaust gas reflow problem based on a certain type of turbocharged diesel engine. The EGR performance test is accomplished and an optimal EGR decision-making optimization method based on grey correlation coefficient modified is proposed. The results show that the venturi tube EGR can basically meet the injection requirements of high-pressure exhaust gas and achieve good results. Through the venturi tube EGR, the NO X emissions reduce significantly with the maximum drop of 30.6%. The explosive pressure in cylinder reduces with the EGR rate increases and the cylinder pressure curve shows a single peak at low-speed conditions and double peaks at high-speed condition. However, the fuel consumption rate, NO X and smoke have been negatively affected. Due to small samples, the traditional evaluation method is difficult to determine the optimal EGR rate reasonably, while the proposed method can effectively solve this problem. It can weaken the shortcomings of subjective judgement and greatly improve the rationality of decision-making results.

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