Nitrogen Oxides Emission Of Diesel Engine Research Articles

Combined Effect of a Catalytic Reduction Device with Waste Frying Oil-Based Biodiesel on NOx Emissions of Diesel Engines

Internal combustion engines with application in automobiles and other relevant industries constitute significant environmental pollution via the release of toxic exhaust gasses like carbon monoxide (CO), hydrocarbons (HC), particulate matter (PM), and nitrogen oxide (NOx). Engine researchers and manufacturers are challenged to develop external and internal measures to ensure environmentally friendly solutions to accommodate and conform to the growing list of emission standards. Therefore, this work presents an experimental investigation of the NOx emission profile of a diesel engine that is fuelled and fitted with waste frying oil-based biodiesel and catalytic converter. Using a single-cylinder, four-stroke air-cooled CI engine at a constant speed of 1900 rpm and different loadings of 25%, 50%, 75%, and 100%; fitted with a catalytic converter at the exhaust outlet of the engine and linked to a dynamometer and a gas analyser, an experiment was conducted at biodiesel/diesel volume blends of B0 (0/10), B5 (5/95), B20 (20/80), B30 (30/70), B70 (70/30), B100 (100/0); and 30% concentration (v/v), 0.5 litre/hr flow rate of aqueous urea from the catalytic converter. The results show an increasing NOx emission as the biodiesel component increased in the blend. The catalytic converter showed a downward NOx reduction with a significant 68% reduction in efficiency at high exhaust gas temperatures. It is concluded that the combined utilisation of waste frying oil-based biodiesel and the catalytic converter yields substantial NOx emission reduction.

Research on the Influence of Euro VI Diesel Engine Assembly Consistency on NOx Emissions

The assembly consistency of a diesel engine will affect its nitrogen oxides (NOx) emission variation. In order to improve the NOx emissions of diesel engines, a study was carried out based on the assembly tolerance variation of the diesel engine’s combustion system. Firstly, a diesel engine which meets the Euro VI standards together with the experimental data is obtained. The mesh model and combustion model of the engine combustion system are built in the Converge software (version 2.4, Tecplot, Bellevue, DC, USA), and the experimental data is used to calibrate the combustion model obtained in the Converge software. Then, the four-factor and three-level orthogonal simulation experiments are carried out on the dimension parameters that include nozzle extension height, throat diameter, shrinkage diameter and combustion chamber depth. Through mathematical analysis on the experimental data, the results show that the variation of nozzle extension height and combustion chamber depth have a strong influence on NOx emission results, and the variation of combustion chamber diameter also has a weak influence on NOx production. According to the regression model obtained from the analysis, there is a quadratic function relating the nozzle extension height and NOx emissions and the amount of NOx increases with increasing nozzle extension height. The relationship between emission performance and size parameters is complex. In the selected size range, the influence of the variation of the chamber diameter on NOx is linear. The variation of the chamber depth also has an effect on NOx production, and the simulation results vary with the change of assembly tolerance variation. Thus, in the engine assembly process, it is necessary to strictly control the nozzle extension height and combustion chamber depth. The research results are useful to improve the NOx emission of diesel engine and provide a basis for the control strategy of selective catalytic reduction (SCR) devices.

Improvement on the linear and nonlinear auto-regressive model for predicting the NOx emission of diesel engine

Given the increasingly stringent emission regulations, an accurate model of emission prediction is required for the aftertreatment systems of diesel engines. For example, the selective catalytic reduction system can realize higher accuracy emission control if the mass of nitrogen oxides (NOx) is known. Given its simplicity, convenience, and effectiveness, the method of data-driven modeling has been widely researched and considered a primary method to estimate the NOx mass before it reaches the aftertreatment device of a diesel engine. To fully use the known engine operating data and therefore improve the prediction accuracy, this study proposes and develops a general linear and nonlinear auto-regressive model with exogenous inputs (GNARX) for NOx prediction. A recursive least square algorithm with forgetting factor is given to estimate the model parameters, and a new simulated annealing based pruning algorithm is developed to identify the model structure. The proposed methods are first used to model the simulation and engineering data to validate their effectiveness and superiority in comparison to the conventional methods. Based on gray relational analysis, the main factors that influence NOx formation, such as the net engine torque, turbo speed, and accelerator pedal position, are then determined as the inputs for modeling the NOx emission of the diesel engine. The results show that the modeling and prediction accuracy of the GNARX model are higher than those of other models, which indicates that the GNARX model is feasible to predict NOx emission.

Emissions Reduction Potential of Closed-Loop Intake Oxygen Control

In this paper it is shown that the oxygen concentration in the intake manifold is the most promising control variable to influence the nitrogen-oxide emissions of Diesel engines via exhaust gas recirculation. A virtual oxygen sensor for the intake manifold is presented. Further the patented IAV closed-loop control concept for the intake manifold oxygen concentration is shown. The dynamic capability and steady-state accuracy of the virtual oxygen sensor and the closed-loop oxygen control are proven by measurements from the engine test bench. Finally, the emissions reduction potential analysis shows that the closed-loop control of oxygen concentration in the intake manifold reduces the nitrogen-oxide emissions by 27 % compared with a conventional closed-loop air-mass flow control.

A fast and accurate physics-based model for the NOx emissions of Diesel engines

To date, models for the nitrogen-oxide emissions of Diesel engines are either of empirical or phenomenological nature. The former are fast and quantitatively accurate in the identified region, but lack the generality and extrapolation capability of the latter. The model presented in this work combines the advantages of both model types and thus complies with typical requirements of computationally intensive fields such as dynamic optimisation and model-based control. This unique aggregation of features is achieved by extracting the most relevant physical phenomena and extending them by physically motivated empirical elements. Exploiting the assumptions made and using a setpoint-relative formulation leads to a simple model structure, comprising one map and 10 scalar parameters only. Execution speed is roughly 500 times faster than real-time and throughout the entire engine operating-range, also during transient operation, relative errors are below 10% even for the largest allowable, simultaneous variation of all inputs. Apart from engine speed and injected fuel-mass, the model requires the cylinder-charge, its composition, and the start of combustion with the corresponding pressure and temperature as inputs. The latter can either be obtained from measured in-cylinder pressure signals, or may be calculated from quantities provided by a model for the air path of the engine.

舶用機関におけるＮＯｘ排出量の経年変化

The amount of nitrogen oxide (NOx) emitted from marine diesel engines is limited by the regulation 13 of Annex VI of MARPOL 73/78. It is provided in the regulation that NOx emissions of marine diesel engines are to be checked when manufactured or installed or remodeled. This regulation seems to have been enacted on the assumption that the emissions have the maximum at manufacturing or remodeling and decrease with ship's ages.To confirm this, authors have measured NOx emissions of an actual vessel for five years. And, the changing trend in NOx emissions with ship's ages was examined based on the measured data. In addition, the relation between NOx emissions and engine parameters was investigated in order to determine what factors have a significant effect on NOx emissions.