NOx Emissions Of Diesel Engine Research Articles

Optimization control strategy for diesel urea-selective catalytic reduction (SCR) urea injection based on the interior point method (IP) + higher order SCR model

In order to ensure that the NOx and NH3 emissions of diesel engines comply with the Euro VII emission standards, this paper optimizes the urea injection using a SCR model combined with the interior point method. First, the equations of the higher-order SCR model were simplified by the variable substitution method and the line method and solved by the backward difference formula to improve computational accuracy. The Levenberg-Marquardt algorithm was used to calibrate the chemical reaction rate parameters to optimize model performance. Second, an optimization cost function was designed to optimize the upstream NH3 concentration in combination with the interior point method and the higher-order SCR model to meet the requirements of Euro VII emission standards. Third, the model effect was verified by performing WHTC hot-start testing on an engine complying with the National VI emission standard. The results show that the average error between the measured NOx concentration and the calculated is 1.49 ppm, which verifies the high accuracy of the model. Finally, the effects of the interior point method, NSGA-II, and MOPSO algorithms in optimizing the upstream NH3 concentration were compared. The results showed that the interior point method outperformed the other algorithms in terms of optimization time and effect, with an optimization time of 149 s, a NOx conversion rate of 97.36 %, and an average downstream NH3 concentration of 4.65 ppm. This achieved a high NOx conversion rate and low NH3 slip in accordance with the requirements of the Euro VII regulation.

Research on input parameter optimization for NOx deep learning prediction model

Optimizing the input parameters for NOx prediction model is instrumental in enhancing the precision and efficacy of the prediction model. This paper focuses on the input variables of the data-driven diesel engine NOx prediction model. According to the diesel engine NOx generation mechanism, at first relevant variables are selected, then the similarity method and parameter sensitivity method are compared to optimize the input variables. Firstly, this paper conducted a real-road emission test of a heavy-duty diesel vehicle, and proposed a data-driven deep learning model for predicting diesel engine NOx emissions based on the experimental data. The experimental data were processed using an Attention-Mechanism based Convolutional Neural Networks-Long Short-Term Memory (AM-CNN-LSTM) model. Subsequently, input parameters were selected according to the sensitivity weights assigned to each parameter in the preliminary model. This approach refined the modeling data and excluded variables not pertinent to NOx emission prediction. The AM-CNN-LSTM model prediction performance has been improved with 2% increase of model R2 as well as the model training time is reduced by 23%, and the types of parameters required to train the model are reduced by 50%. It accomplished this by effectively reducing data dimensions, discarding non-essential variables for NOx prediction, and diminishing computational complexity. Six input parameters were identified as pivotal in reconstructing the modeling data for accurate NOx prediction: engine speed, torque, EGR valve position, exhaust flow rate, air mass flow rate, and oil temperature. In optimizing the NOx prediction model, it is crucial to determine an optimal number of input parameters. Excessive parameters do not enhance model accuracy, while an insufficient number impairs the model’s ability to precisely emulate the NOx generation process, leading to diminished predictive accuracy.

Optimization of NOX emissions of a CRDI DIESEL engine using CMA-ES method

Engine calibration is the tuning of embedded parameters in the engine control unit (ECU) software to improve vehicle characteristics and meet legal requirements. Due to the stricter emission limits and rising customer expectations, current ECU software may include variables up to 30,000, which require very much time for engine calibration development. For this reason, automotive manufacturers continuously develop mathematical-based optimization methods to find optimum operating conditions for the engines. This study aimed to develop an online optimization algorithm to conduct automated dynamometer tests in the calibration development process. A modified covariance matrix adaptation (CMA) algorithm, which is an evolutionary strategy (ES) method belonging to meta-heuristic optimization, was integrated with an automation system for online calibration optimization. Some CMA method parameters such as step size and damping factor were initially revised to achieve the method to function efficiently in online engine calibration. Optimization was conducted at three different operating points of a 2-liter common rail direct injection (CRDI) diesel engine, where NOx emission mainly impacts the New European Driving Cycle (NEDC) results. The main injection timing, rail pressure, pilot injection quantity and timing, manifold pressure, and mass air flow were controlled in the optimization process. Optimization targets were determined according to the NOx-PM Pareto curve for each operating point. Covariance matrix adaptation was used to generate Pareto curves. Sixty-five measurements were taken for each operating point in the optimization process. Once optimization targets were determined, optimization occurred at each operating point. A total NOx emission reduction of 3.8% was obtained in the NEDC test, while fuel consumption and PM remained almost the same at steady-state operating points. The modified CMA-ES algorithm is expected to be an efficient method for online calibration optimization.

Role of analytical methods in verifying biodiesel upgrades: Emphasis on nanoparticle and acetone integration for enhanced performance, combustion, and emissions

AbstractThis study aims to address critical challenges such as global warming and energy sustainability by targeting the reduction of high NOx emissions in diesel engines. The effects of acetone (AC) and magnesium oxide (MgO) nanoparticles (NPs) as additives in improving the physicochemical properties of biodiesel derived from renewable, nonedible Pistacia terebinthus oil, which is abundant in Turkey and has a high free fatty acid (FFA) content of 5.8%, were investigated. Due to the high FFA content, a two‐step (esterification followed by transesterification [TR]) method was used for biodiesel production. Additionally, a quantitative analysis of biodiesel obtained by both single (TR) and two‐step methods was performed to address a gap in the literature. The addition of AC and MgO NPs to B20 (80% diesel fuel and 20% biodiesel) fuel resulted in reductions in the rate of pressure rise, instantaneous energy release, cylinder pressure, mean gas temperature, and cumulative heat release rate. However, brake‐specific fuel consumption increased, and brake thermal efficiency decreased. Emissions analyses showed a reduction in CO emissions by 6.65% with AC and 2.10% with AC + MgO, and a reduction in NOx emissions by 41.64% with AC and 46.03% with AC + MgO. However, hydrocarbon emissions increased by 26.48%. The study highlights the synergistic benefits of AC and MgO additives in biodiesel, presenting a viable strategy for improving the environmental and performance metrics of biodiesel blends. It provides new insights into alternative fuel formulations.

Effect of soot particle deposition on porous fouling formation and thermal characteristics of an exhaust gas recirculation cooler

Exhaust gas recirculation (EGR) systems have been successfully employed to reduce the NOx emissions in diesel engines. However, the fouling problem in EGR coolers challenges their capability to comply with stringent environmental regulations. A few numerical simulations have considered the fouling growth in EGR coolers. Those studies modeled the evolving fouling layer to be a solid medium, therefore, fluid flow and convection heat transfer within the fouling layer, which is well-documented to be a porous medium permeable to gas flow, have not been considered yet. As such, the present study investigates the simultaneous effects of the formation of the evolving porous fouling layer (EPFL) at the walls of an EGR cooler and fluid flow and convection heat transfer simulation within this EPFL to determine its coupled effects on the thermal performance of the EGR cooler. This study also investigates the possibility of formation of a steady fouling layer (SFL) because of the opposing effects of the fouling layer growth and deposition rate. The effects of two pertinent dimensionless parameters, namely Darcy number (10-4≤Da≤5×10-3) and Reynolds number (100≤Re≤400) on the time history of the fouling layer growth, deterioration of the thermal performance of the duct, and average Nusselt number ratio (Nuav/Nuavt=0) are studied. The results show that the thermal performance of the duct decreases as the EPFL grows, which agrees well with the available experimental data. It is shown that the steady fouling layer is obtained due to a decrease in thermophoretic force and deposition rate, as a result of the EPFL formation. Finally, a correlation is proposed in terms of Reynolds and Darcy numbers for the time at which the SFL occurs.

A numerical model for diesel engine SCR systems under different inlet NH3 distribution profiles

Selective Catalytic Reduction (SCR) technology is currently used to effectively reduce NOx emissions for diesel engines. The present study aims at building a three-dimensional numerical model to evaluate the NOx conversion efficiency and the NH3 slip in an SCR system, reducing the time and resources necessary for design and development process. A numerical model of an SCR system has been built to integrate species transport, heat transfer and flow characteristics along with kinetics of the chemical reactions. In order to systematically simulate situations where the concentration of NH3 at the inlet is not uniform, different NH3 inlet profiles have been built by using a Multivariate Gaussian Distribution and considering the maximum concentration in different locations. The effect of different geometries and NH3 distribution profiles on the NOx conversion efficiency and NH3 slip has been studied. The behaviour of the system at different inlet temperatures has been explored and the reaction rates in the monolith have been analysed. The study has been extended by studying the effect of different NH3/NO ratios to provide a more complete comparison between different designs. The numerical model has been found useful to take into account many aftertreatment system parameters during the design of an SCR system, maximize the NOx conversion efficiency by modifying the NH3/NO ratio while minimizing the NH3 slip, providing a comprehensive tool for the optimization of geometrical characteristics of an SCR system.

DETERMINATION OF NOX EMISSION FACTOR FOR DIESEL ENGINES OF RECREATIONAL BOATS BY ON-BOARD MEASUREMENT

In this study, NOx emissions from diesel engines of 75 recreational boats were measured on-board in accordance with the simplified method specified in the NOx Technical Code. The study was carried out in boats with ranging between 14.42 m-37.50 m in length and engines power varying between 138 kW–2,040 kW. NOx emissions were measured by using a portable exhaust gas analyser (Testo 350 Marine) in ppm in a dry basis. An in-house program was developed to calculate the final emission results in g/kWh. The main aim of the study is to develop NOx emission factors for recreational boats, which are not specifically included in previous emission factor studies. The NOx emissions of the marine diesel engines of the recreational boats were found in range of 0.92 g/kWh – 10.69 g/kWh while the mean emission factor was found as 4.81 g/kWh.

EGR and Emulsified Fuel Combination Effects on the Combustion, Performance, and NOx Emissions in Marine Diesel Engines

Techniques such as exhaust gas recirculation (EGR) and water-in-fuel emulsions (WFEs) can significantly decrease NOx emissions in diesel engines. As a disadvantage of adopting EGR, the afterburning period lengthens owing to a shortage of oxygen, lowering thermal efficiency. Meanwhile, WFEs can slightly reduce NOx emissions and reduce the afterburning phase without severely compromising thermal efficiency. Therefore, the EGR–WFE combination was modeled utilizing the KIVA-3V code along with GT power and experimental results. The findings indicated that combining EGR with WFEs is an efficient technique to reduce afterburning and enhance thermal efficiency. Under the EGR state, the NO product was evenly lowered. In the WFE, a considerable NO amount was created near the front edge of the combustion flame. Additionally, squish flow from the piston’s up–down movement improved fuel–air mixing, and NO production was increased as a result, particularly at high injection pressure. Using WFEs with EGR at a low oxygen concentration significantly reduced NO emissions while increasing thermal efficiency. For instance, using 16% of the oxygen concentration and a 40% water emulsion, a 94% drop in NO and a 4% improvement in the Indicated Mean Effective Pressure were obtained concurrently. This research proposes using the EGR–WFE combination to minimize NO emissions while maintaining thermal efficiency.

The influence of water injected on the reduction of NOx emissions in Diesel engine

In recent years, diesel engine manufacturers have been looking for ways to reduce NOx emissions and smoke emissions to meet increasingly stringent standards. Although there are exhaust gases treatment methods to reduce NOX emissions, attempts are being made to control their production in the cylinder. Various methods are used to control the production of NOx in the cylinder: flue gas recirculation, multiple fuel injections. These methods lead to increased fuel consumption and pollutant emissions. To reduce the emission of NOx, the temperature in the combustion chamber must be reduced. By introducing water into the combustion chamber, the desired effect is obtained. In this paper we have studied the effect of lowering the temperature in the combustion chamber on the power of the engine and the emissions of NOx and particles. The study was made on a Renault 4-cylinder diesel engine, water cooled. During operation, a quantity of 5%, 10% and 20% of the amount of diesel introduced into the cylinder was injected into the intake manifold. During the tests, the engine power decreases with 3%. NOx emissions decreased by up to 22%, but particulate emissions increased by about 36%.

Prediction of heat release and NOx emissions for direct-injection diesel engines using an innovative zero-dimensional multi-phase combustion model

Most of the current zero-dimensional (0D) predictive combustion models for diesel engines are based on their simple artificial assumptions rather than actual diesel spray processes, resulting in poor prediction accuracy. Conventional multi-zone models have good prediction performance but a long CPU time. This paper presents an innovative mechanism-based 0D multi-phase combustion model for direct-injection diesel engines. This model was primarily developed to reduce the CPU time for the zero/one-dimensional (0D/1D) simulation of engine performance and improve the optimization efficiency. The main idea of the model was accurately partitioning the spray zone according to different combustion mechanisms based on the concentration field of diesel spray. A representation method of each combustion phase based on the information of concentration field and equivalent injection velocity was proposed. In particular, some special modeling efforts were made to describe the diffusion combustion phase entirely and concisely. Diffusion combustion in different concentration areas exhibited different mechanisms, and diffusion combustion after the end of injection showed a slower burn rate than that during the injection process. All the different conditions of diffusion combustion were considered in this model based on the proposed representation method. Moreover, the in-cylinder temperature was divided into two zones to evaluate the NOx emissions. Extensive experiments were performed using two different diesel engines. The influence of engine speed, injection timing, load, and injection pressure on the combustion process and NOx emissions were investigated. High prediction accuracy was confirmed over a wide operating range. The prediction accuracy of both the heat release rate and NOx emissions of the proposed model was found to be comparable to that of a conventional multi-zone packet model. Compared with the packet model, the proposed model could reduce more than 90% of the CPU time, which significantly improved the engine performance simulation and optimization efficiency.

Review of Optical Diagnostic Technique for Diesel Spray

To enhance the fuel efficiency and reduce both NOX and soot emissions in diesel engine, it is essential to understand the mixture formation and the combustion process in the cylinder. The injection parameters such as pressure, mass and multiple approaches as well as the impingement play an important role in mixture formation, combustion process and emissions. Previous works have addressed various optical diagnostic techniques. This review describes those factors mentioned above systematically to clarify the diesel spray in the compression ignition engine. Therefore, a diesel vehicle with better fuel economy and low emission that meets the stringent regulation across the world could be realized.

Combustion and emission characteristics of diesel with different distillation ranges on the China-VI diesel engine

In this study, hydrocarbon compositions of two types of diesel with different distillation range indexes T90 and T95 were analyzed by gas chromatography-mass spectrometry combined with gas chromatography-field ionization-time of flight mass spectrometry (GC-FI TOF MS), to evaluate the effect on the combustion characteristics and exhaust emissions of three diesel engines. The diesel featured by lower T90 and T95 can improve diesel volatilization performance, shorten the ignition delay time and increase the engine combustion efficiency. The BSFC can be reduced by 0.7%, and the CO2 emission can be reduced by 0.69% (WHTC), and 0.94% (WHSC), respectively, as the increasing low carbon numbers of alkane (C8-C20), monocyclic cycloalkane (C7-C16), bicyclic cycloalkane (C9-C15) and tricyclic cycloalkane (C10-C19) and the decreasing of heavy components such as indane, indene, naphthalene, biphenyl, phenanthrene, etc. The diesel with lower T90 and T95 can reduce the original NOx emissions and the exhaust temperature after the vortex, then decrease the combustion temperature in the cylinder. Finally, tailpipe outlet NOx emissions of the China-VI diesel engine decreased by 7.64% (WHTC) and 12.93% (WHSC), respectively. Besides, the diesel with lower T90 and T95 can reduce the content of PAHs with π bonds, and generate a more uniform fuel–air mixture in the cylinder, thus achieving emission reduction of PM by 14.58% (WHTC) and 37.31% (WHSC), and PN reduction by 25.74% (WHTC) and 14.09% (WHSC), respectively.

Effect of Exhaust Gas Recirculation Combined with Selective Catalytic Reduction on NO x Emission Characteristics and Their Matching Optimization of a Heavy-Duty Diesel Engine.

Exhaust gas recirculation (EGR) and selective catalytic reduction (SCR) have become important technologies to reduce the NOx emission of heavy-duty diesel engines and meet the increasingly stringent emission regulations. This paper studied the effect of EGR combined with SCR on the NOx emission characteristics of a heavy-duty diesel engine based on the engine bench test. The results showed that the NO reduction rate of EGR-coupled SCR increased with the increase of engine load, and the effect was no longer significant when the NO reduction rate exceeded a certain limit under the same working conditions. EGR combined with SCR has little effect on NO2 emission reduction, and the increase of engine speed can significantly improve the efficiency of the NO2 reduction rate at 75 and 100% load. 25% opening of the EGR valve (OEV) and 50% OEV have very similar effects on the NOx reduction rate when the engine speed is at a low level. Compared with low engine speeds, increased OEV or ammonia NOx molar ratio (ANR) had a more obvious effect on the NOx reduction rate at high engine speeds. SCR combined with low valve-opening EGR had a more significant effect on the NOx reduction rate. The increase of OEV led to the increase of fuel consumption rate, but the effect on the fuel consumption rate decreased gradually with the increase of diesel engine speed. Meanwhile, this study optimized the matching relationship between OEV and ANR based on the data of the genetic algorithm, which provides a theoretical research method and application basis for diesel engine-matching of EGR and SCR.

Effect of assisted hydrogen on combustion and emission characteristics of a diesel engine fueled with biodiesel

In this paper, the effects of hydrogen assisted biodiesel with different fatty acid methyl esters (FAMEs) proportion on cylinder pressure, cylinder temperature, indicated thermal efficiency (ITE), NOx emission, HC emission and CO emission of a marine medium speed diesel engine are studied. The corresponding CFD model is executed by CONVERGE coupled to CHEMKIN, and a chemical kinetic mechanism with 314 reactions and 98 species is developed to accurately simulate the fuel injection and combustion processes. The results show that cylinder pressure, cylinder temperature and ITE increased with increasing HEF. Compared with rapeseed methyl ester (RME) and cottonseed methyl ester (CSME), the cylinder pressures are increased by 16.39% and 16.30% for CSME-6%H2 and RME-6%H2 at 100% load, respectively. The cylinder temperatures are increased by 7.42% and 7.14%, and ITE increased by 3.73% and 3.9%, respectively. In addition, the HC and CO emissions decreased significantly with the increase in HEF, while NOx emission increased. Compared with pure CSME and RME, HC emissions are reduced by 70.97% and 72.22% for CSME-6%H2 and RME-6% H2, and CO emissions are reduced by 41.89% and 38.12% for CSME-6%H2 and RME-6% H2 at 100% load, respectively. Overall, the strategy of using CSME-6% H2 mixed fuel for engine is not only economical and practical, but also can prevent performance loss and reduce emissions.

Application and Development of Selective Catalytic Reduction Technology for Marine Low-Speed Diesel Engine: Trade-Off among High Sulfur Fuel, High Thermal Efficiency, and Low Pollution Emission

In recent years, the International Maritime Organization (IMO), Europe, and the United States and other countries have set up different emission control areas (ECA) for ship exhaust pollutants to enforce more stringent pollutant emission regulations. In order to meet the current IMO Tier III emission regulations, an after-treatment device must be installed in the exhaust system of the ship power plant to reduce the ship NOx emissions. At present, selective catalytic reduction technology (SCR) is one of the main technical routes to resolve excess NOx emissions of marine diesel engines, and is the only NOx emission reduction technology recognized by the IMO that can be used for various ship engines. Compared with the conventional low-pressure SCR system, the high-pressure SCR system can be applied to low-speed marine diesel engines that burn inferior fuels, but its working conditions are relatively harsh, and it can be susceptible to operational problems such as sulfuric acid corrosion, salt blockage, and switching delay during the actual ship tests and ship applications. Therefore, it is necessary to improve the design method and matching strategy of the high-pressure SCR system to achieve a more efficient and reliable operation. This article summarizes the technical characteristics and application problems of marine diesel engine SCR systems in detail, tracks the development trend of the catalytic reaction mechanism, engine tuning, and control strategy under high sulfur exhaust gas conditions. Results showed that low temperature is an important reason for the formation of ammonium nitrate, ammonium sulfate, and other deposits. Additionally, the formed deposits will directly affect the working performance of the SCR systems. The development of SCR technology for marine low-speed engines should be the compromise solution under the requirements of high sulfur fuel, high thermal efficiency, and low pollution emissions. Under the dual restrictions of high sulfur fuel and low exhaust temperature, the low-speed diesel engine SCR systems will inevitably sacrifice part of the engine economy to obtain higher denitrification efficiency and operational reliability.

Experimental and Numerical Analysis of an Innovative Mixer Geometry for Urea Injection in SCR Applications

Selective catalytic reduction (SCR), based on the injection of urea-water-solution (UWS), is one of the prevailing and more effective approaches to reduce NOx emissions in diesel engines. To improve the performance and durability of the system, it is crucial to develop reliable simulation tools able to correctly describe not only the urea conversion into ammonia and the mixing with exhaust gases but also the possible formation of solid deposits along with the engine’s exhaust line.In the present paper, two different exhaust systems for off-road applications are analyzed, both of them consisting of a diesel oxidation catalyst (DOC) followed by a diesel particulate filter (DPF), a UWS injection and a mixing device, and an SCR catalyst. Two alternative UWS mixing subsystems are evaluated, including a newly developed design. A 3D-CFD numerical analysis is carried out to assess the performance of both systems in terms of pressure drop, UWS spray, and liquid film development, in addition to flow velocities and species concentration uniformities at SCR catalyst inlet. A detailed analysis of droplet impingement on walls and liquid film development is enabled, thanks to a conjugate heat transfer (CHT) approach. Moreover, a deposit risk index is used to identify the areas of the systems where urea deposit formation is expected.Eventually, numerical results are compared with experiments on one operating condition chosen as the most challenging in terms of exhaust temperature and flow rate, both in terms of systems NOx conversion efficiency and deposit formation, showing a satisfactory agreement, thus paving the way to use the proposed synergetic numerical and experimental approach to further optimize the design and the system’s performance.

Optimization Analysis of Locomotive Diesel Engine Intake System Based on Matlab-Simulink and GT-Power

In this paper, based on the coupling calculation of Simulink software and GT-Power software, an Optimizer model method was proposed for a 16V265H diesel engine to study the effects of different ratios of biodiesel (B0, B10, and B20) on the performance of a 16V265H diesel engine at 1000 rpm and 75% load. Firstly, the four parameters of diesel engine power, BSFC, soot emission, and NOx emission were taken as the result variables of the optimization model. Taking the intake and exhaust timing of the diesel engine as the independent variable of the optimization model, the maximum power, minimum BSFC, and minimum diesel engine emission were studied and analyzed. Finally, the performance parameters were comprehensively analyzed to determine the best intake and exhaust valve timing. Moreover, based on the model optimization, the diesel engine’s BSFC and power performance were compared, and the optimal intake timing scheme for the diesel engine with different biodiesel ratios at 75% operating conditions was obtained. The results showed that the maximum power, optimum BSFC, and minimum emissions of the 16V265H diesel engine with different ratios of biodiesel and different intake valve timing angles were also different. Under 75% load conditions, the BSFC reduction rate was up to 6.32%, and the power increase rate was up to 5.87%. In addition, by optimizing the model with B10 biodiesel and the intake valve timing close to 202°CA and the exhaust valve timing close to 98°CA, the diesel engine had the lowest NOx emission; with B10 biodiesel and the intake timing at 180°CA, the diesel engine had the lowest BSFC; and with B10 biodiesel and the intake valve timing close to 179.5°CA, the diesel engine had the maximum power. In conclusion, the diesel engine is best with B10 biodiesel. This research method can provide a reference for implementing variable intake system technology for the 16V265H diesel engine.

Analysis of Exhaust Gas Emissions on Dual Fuel Diesel Engine Single Cylinder Four-stroke with LPG-Diesel Oil

Diesel engine is one of type of internal combustion engine that is applied in industry, including the maritime industry. The increasing use of diesel engines, has a effect on increasing emissions. Diesel engines emissions consist of SOx, NOx, HC, and others. To reduce the emissions, there are many method, one of them is using dual-fuel system. The alternative fuel can be used is Gas, which is easily available, namely LPG or liquefied petroleum gas. To supply LPG to combustion chamber, a converter-kit are needed to be install on diesel engine. There are several previous research that prove that LPG can be used as an alternative in a dual-fuel system and can reduce the emissions. One of them by Ma’amuri (2016) who designed a mechanical LPG-diesel oil as dual-fuel, using a membrane converter. Result of this research provide that good diesel engine performance. In this research, LPG-diesel oil as dual-fuel using converter kit based on ECU or electronic control unit, and then, analyze the diesel engine emissions with experimental method. The purpose of this research is to determine the emissions produced by LPG-diesel oil as dual-fuel with converter kit based ECU. After taking and analytical data, known that the NOx emission from dual fuel diesel engine using ECU-based converter kit is lower than NOx emission from conventional diesel engine with B30 diesel fuel with percentage is 25,61 % for 3ms opening duration of gas injector, 39,99 % for 4 ms opening duration of gas injector and 26,5 % for 5 ms opening duration of gas injector. The NOx emission of conventional diesel engine is 2,46 g/kWh.

Experimental investigation of the effect of urea addition to fuel on engine performance and emissions in diesel engines

Today, exhaust emissions have become a critical issue with the increasing number of vehicles due to greenhouse gas. Engine manufacturers carry out R&D studies due to emission limitations imposed on engines that use fossil fuels. Selective Catalytic Reactor and AdBlue injection systems have been used significantly to reduce NOx emissions in diesel engines. For this reason, AdBlue is sprayed in the exhaust manifold to reduce emissions with a second injector in diesel engines. In this study, the effects of commercial AdBlue, Urea-pure water mixture and urea- pure water-citric acid mixtures as additives to diesel fuel on exhaust emission and performance in a diesel single-cylinder engine were investigated. In-cylinder pressure, exhaust gas temperature, fuel consumption, air consumption and exhaust emissions were measured experimentally to examine the effects of 3 different mixtures added to diesel fuel at 8 different loads. As a result, urea-citric acid–water mixtures added to diesel fuel worsened combustion. Brake fuel specific consumption has increased 8% for diesel + urea + citric acid mixtures due to the presence of water in mixtures. CO2 emissions increased by 38% with the addition of AdBlue, while an increase of 53% was observed with the addition of diesel + urea + citric acid. With the addition of urea + citric acid to diesel fuel, CO emissions decreased by 233%, while under the same conditions, HC emissions decreased by 300% and NOx emissions decreased by a maximum of 19%.

Effects of Catalyst Physicochemical Properties on the Catalytic Activity of Cu Zeolite Selective Catalytic Reduction at Different Inlet Gas Conditions

Selective catalytic reduction (SCR) systems are important technical means of mitigating NOx emissions for diesel engines. The major challenge of this technique is to improve the low-temperature act...