Off-road Diesel Engine Research Articles

Numerical optimization and experimental investigation of renewable diethyl ether-fueled off-road CI engines for sustainable transportation

Cleaner energy generation on light-duty off-road diesel engines is one of the objectives of this study, which utilizes renewable diethyl ether (DEE) as a replacement for diesel to minimize the reliance on fossil diesel fuel. In an air-cooled single-cylinder diesel engine, various DEE mixes of 5, 10, 15, 20 and 25% were attempted and evaluated under varying loads (0, 25, 50, 75 and 100%) in an effort to enhance the performance and emission characteristics of agriculture diesel engines and lower the environmental effect of harmful emissions. The injection pressure was optimized using computational fluid dynamics (CFD), and performance and emission outcomes were optimized through response surface methodology (RSM) techniques. The experimental results found that brake thermal efficiency and specific fuel consumption were enhanced for a higher proportion of DEE blends under increasing loads. In addition, increasing the engine load decreased CO emissions while increasing carbon dioxide (CO2), hydrocarbon (HC), and nitrogen oxide (NOx) emissions. Reduced CO, NOx, and HC emissions and increased CO2 were realized in the blended fuel samples compared to those of pure diesel fuel at increasing DEE percentages. In summary, the utilization of a 15% DEE blend and the optimization of the injection pressure to 210 bar resulted in a notable improvement of 10% in thermal efficiency and a decrease in emissions by 5% when compared to other parameters.

Variable valve actuation for efficient exhaust thermal management in an off-road diesel engine

Exhaust thermal management (ETM) is crucial for effective emission mitigation in integrated exhaust aftertreatment systems of modern off-road diesel powertrains. However, conventional ETM strategies incur a significant fuel efficiency penalty. This study addresses the issue by investigating the application of variable valve actuation (VVA) for efficient ETM. For the first time, this investigation is conducted on a representative state-of-the-art off-road powertrain platform. It explores four VVA strategies with unprecedent level of rigour, employing a model-based approach that enables extended insights beyond stand-alone testing. Experiments with an EU Stage-V off-road diesel engine provide the baseline for validating a one-dimensional model in GT-Suite. A meticulously calibrated, predictive combustion model enables precise cross-evaluation of how VVA strategies affect exhaust gas temperature (EGT), efficiency, engine-out emissions and combustion characteristics, considering all trade-offs. VVA simulations are performed at three low-load operating points, where engine operation borders catalyst light-off temperature (LOT). The findings impartially confirm that cylinder deactivation (CDA) and intake modulation are the most promising VVA strategies for off-road engines, with EGT increments surpassing +250 °C and +150 °C respectively, accompanied by minor fuel penalties (up to +3.5 %). CDA demonstrated fuel savings of up to −2.5 % at certain points, due to reduced pumping and friction losses. Intake modulation displayed large reduction in engine-out NOx (>90 %) and minimal penalties in carbon emissions (HC, CO, and soot). The results underscore VVÁs potential as an efficient ETM option to help the next generation of off-road diesels to comply with upcoming EPA Tier 5 emission legislation.

Optimization of homogeneous charge compression ignition combustion in a light-duty diesel engine operated using ethyl acetate-gasoline blends

The low temperature combustion mode of homogeneous charge compression ignition eliminates particulate matter and oxides of nitrogen (NO x) emissions trade-off that prevails in high-temperature, diffusion-controlled conventional diesel combustion (CDC). In the present research, the significant challenge of narrow operating load range that hinders the commercial implementation of light-duty HCCI engines was overcome by employing ethyl acetate-gasoline blends. The gasoline concentration in test fuels was reduced in 10% decrements, from 84% to 24%, to replace it with ethyl acetate. The use of ethyl acetate, a renewable fuel, can help solve the energy crisis due to the rapid depletion of fossil fuels. An ignition improver was blended in the test fuels in a predetermined amount of 6% so that combustion stability was not hampered at lower loads. Parametric investigations were conducted to study the effect of progressively increasing ethyl acetate in test fuels on HCCI combustion, performance, and emissions. The machine learning tool of artificial neural network was implemented to learn the behavior of the test engine, considering load and fuel composition as input variables. The feedforward artificial neural network models were developed to predict the start of combustion, combustion phasing, indicated thermal efficiency, and emissions of carbon monoxide, soot, NO x, and unburned hydrocarbon (HC). A multi-objective optimization was performed to arrive at the best operating condition by integrating artificial neural network models with the genetic algorithm. All the developed artificial neural network models could predict responses with acceptable accuracy. The genetic algorithm indicated that the optimum point of the operation was at 80% load and 65% ethyl acetate in the test fuels. Experiments were conducted to validate the optimal HCCI conditions that resulted in 27% higher indicated thermal efficiency, 54% lower HC+NOx, and 99% lower soot emissions than CDC. Overall, the present study demonstrated the benefits of considering ethyl acetate as a fuel to improve HCCI engine metrics of off-road diesel engines.

Sustainable biodiesel from flex-mix feedstock and its combustion in a VCR-CRDI engine with variable exhaust gas recirculation and injection pressure

Biodiesel produced from single feedstocks has many challenges due to variations in the oil properties. The flex-mix approach is a long-term solution for turning mixed feedstock into high-quality biodiesels. In this investigation, a pre-mixed used cooking oil and animal fat (pig fat) mixture (from 20% to 80%) was transesterified to produce flex-mix methyl ester (FMME). The FMME fuel characteristics were tested and compared to biodiesel standards. Generally, biodiesel emits higher oxides of nitrogen (NO x ) gas due to the presence of highly unsaturated compounds and oxygen. The present study aims to address this issue by adopting the flex-mix approach in combination with fuel injection strategies (400, 500 and 600 bar), exhaust gas recirculation (EGR 10%, 20% and 30%) and variable compression ratio (CR 17.5:1, 20:1 and 22:1). At a CR of 22 and an injection pressure (P inj) of 600 bar, the FMME fuel without EGR shows a minimum reduction in brake thermal efficiency of 0.15% when compared to diesel. Nitric oxide gas emissions decreased by nearly 50% for all P inj and EGR values, but they rose when the compression ratio was increased to 20 and 22. Smoke and hydrocarbon emissions also increased with the exhaust gas proportion. The engine performance with FMME fuel was found to be equivalent to that with fossil diesel fuel. According to the findings, the flex-mix approach could be a long-term alternative to producing renewable fuel for off-road diesel engine application.

Experimental and simulation study on aluminium alloy piston based on thermal barrier coating

Thermal barrier coatings (TBCs) have low thermal conductivity, effectively reducing the temperature of the metal matrix and improving thermal performance, knock resistance, and combustion performance of the piston. In this study, an off-road high-pressure common-rail diesel engine was chosen as the research object. Combined with the test results of the piston temperature field under the rated power and maximum torque conditions, a finite element simulation model of the thermal barrier coating piston was established. This model enabled the distribution characteristics and variation laws of the temperature field, stress, and deformation of the thermal barrier coating on the piston matrix to be analysed. The results show that the maximum temperature of the TBC piston is 12.2% and 13.73% lower than that of the aluminium alloy piston under the rated power and maximum torque conditions, respectively. The thermal stresses of the TBC piston at the top of the cavity were 25.9% and 26.8% lower than those of the aluminium piston, while the thermo-mechanical coupling stress of the TBC piston was slightly higher than that of the aluminium piston—1.2 MPa and 3.7 MPa in the bottom of the combustion chamber with geometric mutation, respectively. The radial thermal deformation of the TBC piston was 0.067 mm and 0.073 mm lower than that of the aluminium piston, with the radial thermo-mechanical coupling deformation also decreasing by 0.069 mm and 0.075 mm, respectively. The radial thermal deformation of the piston in the direction parallel to the pinhole axis was greater than that in the direction perpendicular to the pinhole axis; the difference in the magnitude of the change results in uneven thermal deformation of the piston.

Experimental and simulation study on heat transfer characteristics of aluminium alloy piston under transition conditions

In order to explore the thermal load change of the diesel engine piston under transitional conditions, and the influence of the position of cooling gallery on the heat transfer characteristics of the piston. An off-road high-pressure common-rail diesel engine is chosen as the research object. The sequence coupling method is used to establish the fluid–solid coupling heat transfer simulation model of the piston-gallery under the transition conditions of cold start, urgent acceleration and rapid deceleration. The Pareto optimization algorithm is introduced to optimize the position of the cooling gallery to reduce the maximum temperature and maximum thermal stress of the piston. The results show that the maximum temperature of the piston can be reduced by reducing the distance between the cooling gallery and the throat area under the maximum torque condition, and that the maximum thermal stress of the piston can be reduced by reducing the distance between the cooling gallery and the throat area or by increasing the distance between the cooling gallery and the ring area. Compared with the original design, the maximum temperature of Design A decreases by 1.28 °C while the maximum thermal stress decreases by 2.07 MPa. The maximum temperature and maximum thermal stress of Design B decreases by 0.22 °C and 0.5 MPa, respectively. The maximum thermal stress of Design C decreases by 2.67 MPa when the maximum temperature increases by 1.15 °C. The maximum change in temperature of the three typical designs and the original design of the piston throat under cold start, urgent acceleration and rapid deceleration conditions reached 207.29 °C, 136.78 °C and 9.89 °C, and the maximum change of thermal stress reached 8.62 MPa, 20.43 MPa, 4.08 MPa, respectively. The maximum change in temperature of the piston first ring groove under cold start, urgent acceleration and rapid deceleration conditions reached 172.00 °C, 83.52 °C and 7.36 °C, and the maximum change in thermal stress reached 22.96 MPa, 43.10 MPa, 5.72 MPa, respectively. The conclusions obtained can provide boundary conditions for further study of the thermal load change law of the same type of pistons, and also provide a theoretical basis for diesel engine piston structure optimization and the performance improvement.

Effects of hydrogenated vegetable oil (HVO) and HVO/biodiesel blends on the physicochemical and toxicological properties of emissions from an off-road heavy-duty diesel engine

In this study, the regulated emissions, gaseous toxics, and the physical, chemical, and toxicological properties of particulate matter (PM) emissions from a legacy off-road diesel engine operated on hydrogenated vegetable oil (HVO) and HVO blends with biodiesel were investigated. This is one of the very few studies currently available examining the emissions and potential health effects of HVO and its blends with biodiesel from diesel engines. Extended testing was conducted over the nonroad transient cycle (NRTC) and the 5-mode D2 ISO 8718 cycle. Nitrogen oxide (NOx) emissions showed statistically significant reductions for HVO compared to diesel, whereas the biodiesel blends statistically significant increases in NOx emissions. PM and solid particle number reductions with pure HVO and the biodiesel blends were also observed. Low-molecular weight polycyclic aromatic hydrocarbons (PAHs) were the dominant species in the exhaust for all fuels, with pure HVO and the biodiesel blends showing lower concentrations of these pollutants compared to diesel fuel. Our results showed that the oxidative stress and cytotoxicity in PM emissions decreased with the use of biofuels. Notable correlations were observed between PM emissions and oxidative stress and cytotoxicity, especially elemental carbon and particle-phase PAH emissions.

Effects of dual fuel combustion on performance, emission and energy-exergy characteristics of diesel engine fuelled with diesel-isobutanol and biodiesel-isobutanol

This experimental study investigates the effects of dual fuel combustion (DFC) of isobutanol on performance, emission, and energy-exergy characteristics of an off-road diesel engine using diesel and waste cooking oil biodiesel. The isobutanol is port injected at the premixed energy ratio (PER) of 10, 20, and 30% with intake air, while diesel, B20, and B100 are the direct in-cylinder injected fuels. The experiments indicated an improved brake thermal efficiency in DFC of diesel and B20 (1.22 and 5.27%) than their conventional combustion mode (CCM) at rated loads. The carbon monoxide emission from DFC is reduced than CCM at rated loads except B100. The DFC reduced the nitrogen-oxides (NOx) emission than CCM up to intermediate loads (60%). Compared to CCM, smoke emission at the rated load is lowered by 10.15%, 22.12%, and 7.40% in the DFC of diesel, B20, and B100 respectively at 30% PER. At 30% PER, the exergy efficiency of DFC of B20 is increased by 0.91, 5.23, 3.65, 1.22, and 6.14% from 20% to 100% loads compared to its CCM. Overall, the DFC of B20-isobutanol with 30% PER is observed to be a better choice in terms of improved performance, NOx and smoke emissions, and exergy efficiency.

Evaluation of small off-road diesel engine emissions and aftertreatment systems

Off-road engines represent one of the largest categories for mobile source emissions in the United States. Emissions standards for small off-road diesel engines (SORDEs), which have not been updated since 2004, can be met without the use of aftertreatment on engines below 75 horsepower (hp) for nitrogen oxides (NOx) or below 25 hp for particulate matter (PM). It has been well established that aftertreatment systems can significantly decrease mobile source emissions, and improvements in these technologies since 2004 could warrant consideration for adopting more stringent standards for the SORDE category. This study evaluated the feasibility, efficiency, durability, and cost benefit of implementing regulations strict enough to require the use of selective catalytic reduction (SCR) and diesel particulate filter (DPF) controls on off-road engines under 75 hp. Durability testing was performed and emissions assessed on four stock engines equipped with retrofitted aftertreatment systems. The results suggest adding a DPF can provide >98% PM reductions. SCR systems provided NOx reductions ranging from 26 to 91% largely dependent on the cycle tested and engine exhaust temperature profile. Adoption of new SORDE standards could provide a PM reduction of 3.8% and a NOx reduction of 8.8–13.7% for the total off-road equipment inventory in California.

Decrease in ambient volatile organic compounds during the COVID-19 lockdown period in the Pearl River Delta region, south China

During the COVID-19 lockdown, ambient ozone levels are widely reported to show much smaller decreases or even dramatical increases under substantially reduced precursor NOx levels, yet changes in ambient precursor volatile organic compounds (VOCs) have been scarcely reported during the COVID-19 lockdown, which is an opportunity to examine the impacts of dramatically changing anthropogenic emissions on ambient VOC levels in megacities where ozone formation is largely VOC-limited. In this study, ambient VOCs were monitored online at an urban site in Guangzhou in the Pearl River Delta region before, during, and after the COVID-19 lockdown. The average total mixing ratios of VOCs became 19.1% lower during the lockdown than before, and those of alkanes, alkenes and aromatics decreased by 19.0%, 24.8% and 38.2%, respectively. The levels of light alkanes (C < 6) decreased by only 13.0%, while those of higher alkanes (C ≥ 6) decreased by 67.8% during the lockdown. Disappeared peak VOC levels in morning rush hours and the drop in toluene to benzene ratios during the lockdown suggested significant reductions in vehicle exhaust and industrial solvent emissions. Source apportioning by positive matrix factorization model revealed that reductions in industrial emissions, diesel exhaust (on-road diesel vehicles and off-road diesel engines) and gasoline-related emissions could account for 48.9%, 42.2% and 8.8%, respectively, of the decreased VOC levels during the lockdown. Moreover, the reduction in industrial emissions could explain 56.0% and 70.0% of the reductions in ambient levels of reactive alkenes and aromatics, respectively. An average increase in O3–1 h by 17% and a decrease in the daily maximum 8-h average ozone by 11% under an average decrease in NOx by 57.0% and a decrease in VOCs by 19.1% during the lockdown demonstrated that controlling emissions of precursors VOCs and NOx to prevent ambient O3 pollution in megacities such as Guangzhou remains a highly challenging task.

Towards a Powerful Hardware-in-the-Loop System for Virtual Calibration of an Off-Road Diesel Engine

A common challenge among internal combustion engine (ICE) manufacturers is shortening the development time while facing requirements and specifications that are becoming more complex and border in scope. Virtual simulation and calibration are effective instruments in the face of these demands. This article presents the development of zero-dimensional (0D)—real-time engine and exhaust after-treatment system (EAS) models and their deployment on a Virtual test bench (VTB). The models are created using a series of measurements acquired in a real test bench, carefully performed in view of ensuring the highest reliability of the models themselves. A zero-dimensional approach was chosen to guarantee that models could be run in real-time and interfaced to the real engine Electronic Control Unit (ECU). Being physically based models, they react to changes in the ECU calibration parameters. Once the models are validated, they are then integrated into a Simulink® based architecture with all the Inputs/Outputs connections to the ECU. This Simulink® model is then deployed on a Hardware in the Loop (HiL) machine for ECU testing and calibration. The results for engine and EAS performance and emissions align with both steady-state and transient measurements. Finally, two different applications of the HiL system are presented to explain the opportunities and advantages of this tool integrated within the standard engine development. Examples cited refer to altitude calibration activities and soot loading investigation on vehicle duty cycles. The cases described in this work are part of the actual development of one of the latest engines developed by Kohler Engines: the KDI 1903 TCR Stage V. The application of this methodology reveals a great potential for engine development and may become an essential tool for calibration engineers.

Air quality and waste management analysis of used ayurvedic oil in an off-road twin cylinder tractor engine

ABSTRACT Off-road diesel engines for genset applications, municipal and farming activities are the major contributors to harmful emissions. To address this, the present research reports the use of biodiesel derived from Waste Ayurvedic Oil (WAO) in an off-road twin cylinder compression ignition engine. The methyl ester of WAO was formulated using the ultrasound irradiated transesterification process. The different blends of WAO methyl ester and diesel, say WAO10, WAO15 and WAO20 were prepared and experimented on a Mahindra-Maximo twin cylinder tractor engine in order to analyse its performance, emission and combustion behaviour. As compared to diesel, WAO blends offer increased specific fuel consumption with comparable brake thermal efficiency for WAO10 over all the engine speeds. WAO10, WAO15 and WAO20 diminished CO emissions by 16.12%, 22.58% and 29.03%, HC emission by 19.04%, 42.8% and 61.9% as well as smoke opacity by 14.28%, 28.57% and 42.85% together with amplified NOx emission by 2.73%, 10.95% and 21.5% respectively in comparison with diesel. Therefore, WAO is a cost-effective feedstock for biodiesel synthesis, and its blends could be used as off-road diesel engine substitutes.

Experimental Investigation of Neat Biodiesels’ Saturation Level on Combustion and Emission Characteristics in a CI Engine

The fuel qualities of several biodiesels containing highly saturated, mono, and poly unsaturated fatty acids, as well as their combustion and exhaust emission characteristics, were studied. Six biodiesel samples were divided into two groups based on their fatty acid composition, including group 1 (coconut, castor, and jatropha) and group II (palm, karanja, and waste cooking oil biodiesel). All fuels (in both groups) were tested in a single-cylinder off-road diesel engine. Castor and karanja biodiesel, both rich in mono-unsaturation level, have a high viscosity of about 14.5 and 5.04 mm2/s, respectively. The coconut and palm biodiesels are rich in saturation level with cetane numbers of 62 and 60, respectively. In both groups, highly saturated and poly-unsaturated methyl esters presented better combustion efficiency and less formation of polluted emissions than mono-unsaturation. At full load, coconut and palm biodiesel displayed 38% and 10% advanced start of combustion, respectively, which reduced ignition delay by approximately 10% and 3%, respectively. Mono-unsaturated methyl esters exhibited a higher cylinder pressure and heat release rate, which results in higher NOx gas emissions. The group II biodiesels showed about 10–15% lower exhaust emissions owing to an optimum level of fatty acid composition. Our study concluded that highly saturated and poly-unsaturated fatty acid performed better than mono-unsaturated biodiesels for off-road engine application.

Modal properties diagnostics of the high-pressure fuel injection pipes in off-road diesel engine

Injection systems of modern commercial vehicle power units are still a frequent topic for development engineers in terms of durability and reliability. Therefore, the content of this study is just an investigation of the dynamic behaviour of high-pressure injection pipes of a four-cylinder combustion engine. The modal properties of the injection tubes are evaluated by experimental modal analysis (EMA). Another phase of the measurements is the sensing and analysing of the acceleration on each injection pipe during the engine speed ramp in the entire range of the speed spectrum. There was investigated the modal behaviour of the structure to the operational character of the excitation. The work includes a numerical model established by finite element method (FEM), where the boundary conditions correspond to the real installation of injection pipes from the measurement. The modal properties of injection pipes were primarily investigated through the numerical approach, several variants of pipe attachments were considered in simulations. Comparing the FEM results of different pipe attachments, the suitability of the clamp position with respect to the specific installation in the power unit from the measurement is discussed. From the evaluated results, it is possible to assume the dynamic behaviour of the high-pressure injection pipe in the power unit. Based on the performed analyses, the critical mode shapes of the injection pipes are described considering the engine operating condition. When the engine speed frequency and some pipe eigen frequency interfere together, it is undesirable state. In many cases, this leads to a crack initiation and subsequent damage of the injection pipes during the cyclic load. The presented results and conclusions in this study should improve the overall knowledge on high-pressure fuel pipes in terms of modal properties and its vibration behaviour during operating condition.

Study on Altitude Adaptability of a Turbocharged Off-Road Diesel Engine

Abstract This paper investigates the operating characteristics of an off-road diesel engine to enhance its power performance in plateau. First, the impacts of altitude on the power, fuel economy, and emissions characteristics were analyzed by a bench test. Second, the combustion and overall performance working at different altitudes were studied by three-dimensional numerical simulation, including the relationship between fuel injection parameters and engine performance. The results showed that altitude significantly affects the performance of the off-road diesel engine. As the altitude increased from 0 m to 2000 m, the engine power decreased as much as 4.3%, and the brake-specific fuel consumption (BSFC) increased as much as 6%. At the peak torque condition, the intake manifold boost pressure and the exhaust manifold pressure both reduced with a rise of altitude, while the intake and exhaust manifold temperatures both increased with a rise of altitude. Finally, after comparing the in-cylinder flow conditions and combustion characteristics given by six combustion chamber designs that have different shrinkage ratios, the engine performance at 4000 m altitude with five different fuel spray angles were further optimized. The engine rated power increased by 8.2% when the shrinkage ratio was 7.28% and the fuel spray angle was 150 deg at the 4000 m altitude.

Effects of alternative marine diesel fuels on the exhaust particle size distributions of an off-road diesel engine

The main objective of this study was to find out how alternative fuels affect the exhaust gas particle size distribution. The fuels are later intended for marine applications. Along with low-sulfur marine light fuel oil (LFO), a high-speed off-road diesel engine was fueled by circulation-origin marine gas oil (MGO), rapeseed methyl ester (RME), crude tall oil derived renewable diesel (HVO), the 20/80 vol.-% blend of renewable naphtha and marine LFO, and kerosene. Particle size distributions were measured by means of an engine exhaust particle sizer (EEPS), but soot, gaseous emissions and the basic engine performance were also determined. During the measurements, the 4-cylinder, turbocharged, intercooled engine was run according to the non-road steady cycle complemented by an additional load point. The engine control parameters were kept constant, and any parameter optimization was not made with the studied fuels. Relative to baseline LFO, both naphtha-LFO blend and RME reduced particle numbers above the size range of 50 nm. Circulation-origin MGO and kerosene generated a high total particle number (TPN), most likely due to their higher sulfur contents. MGO and RME were beneficial in terms of carbon monoxide (CO) and hydrocarbon (HC) emissions while nitrogen oxide (NOx) emissions were the highest with RME. The differences in smoke emission were negligible.

Recognition and Separation Technique of Fault Sources in Off-Road Diesel Engine Based on Vibroacoustic Signal

PurposeAcoustic and vibration signals taken from engine often provide significant dynamic information on mechanical and thermodynamic system conditions. The failure characteristics with its quantity description point at the nature and intensity of an incorrectness during normal engine operation, giving the basic principles for more accurate process run monitoring and recognition of fault sources influenced on combustion process run.MethodProblems of failure recognition for CI engine systems have been described. Attributes are created for a combustion run, also for malfunctions in a real engine work maps. The additional new feature of a method is connected with taking into account an empirical signal of combustion runs for each cylinder units and having applied advanced procedures of vibroacoustic signal measures. The way of quantification of combustion changes with accompanying process characteristics in different signal domains was approximated. Accurate recognition and separation of fault cases in normal engine work cycles is the first step of a signal qualification.Results and ConclusionsFault source detection for diesel engine was analyzed and its accuracy was considered to generate the features most sensible for a process changes. The obtained analyses prove that it is capable to extract fault components from vibroacoustic signal run and precisely calculate its intensity point estimators.

Research on torsional vibration reduction of crankshaft in off-road diesel engine by simulation and experiment

Formerly, torsional vibration of crankshaft in off-highway diesel engine (agricultural machinery) were given little attention at their developmental stages, however with increasing agricultural activities, numerous torsional vibration problems have been noted to occur in agricultural machinery, especially in their diesel engines. This results in engine vibration, crankshaft failure and undesirable engine noise. In this paper, a six-cylinder four-stroke inline diesel engine’s crankshaft model was developed using AVL Excite Designer. After experimentally validating the model, it was used to numerically determine the torsional vibrations of a crankshaft. For the reduction of torsional vibration, two methods of crankshaft improvements were proposed based on simulation results. The first method, is to decrease the inertia of the crank pulley while the second, involves the replacement of the crank pulley with a torsional vibration damper. To ensure minimal engine alterations and cost effectiveness, the second improvement method was adopted for improving torsional vibration. Afterwards, engine radiating noise and surface vibration measurements were conducted to ensure that the required limits were achieved by the improved engine. The simulation, experiment and the improvement process of the crankshaft torsional vibration are documented further in this research. These improvements have applicable values in the developmental or quality enhancement stage of diesel engines used in agricultural machinery.

Nitric Oxide Reduction of Heavy-Duty Diesel Off-Gas by NH3-SCR in Front of the Turbocharger

This paper investigates the impacts and effects of higher pressure on NH3-SCR of NOx corresponding to positioning the SCR catalyst in front of the exhaust gas turbine, which is an option in heavy-duty and off-road diesel engine applications (1–4). The influence of applied pressure up to 500 kPa on the selective catalytic reduction (SCR) of nitrogen oxides by NH3 over commercial V2O5/WO3-TiO2-type catalysts (VWT) is studied experimentally and numerically. The model includes a detailed reaction mechanism for standard and fast SCR and a two-dimensional description of the flow field and diffusion in the honeycomb-structured catalyst. The pressure effect on catalytic conversion, residence time, and mass transfer are examined for varying temperature and two different channel sizes, i.e., 25 and 300 cpsi (channels per square inch) at constant mass flux from the engine. Pre-turbo positioning of the catalyst leads to a significant increase in NOx conversion due to higher pressure aside from the positive temperature effect. However, with increasing channel size, diffusional mass transport limits the reaction rate, and reduces the benefit of increased residence time due to the decrease in diffusion rates with increasing pressure. The achievable increase in conversion is transformed into a length reduction of the catalyst.

Biofuel blend late post-injection effects on oil dilution and diesel oxidation catalyst performance

In this article, the effects of different biofuel–diesel blends on engine oil dilution and diesel oxidation catalyst performance during late post-injections were investigated. The engine tests were made with an off-road diesel engine under low load conditions at 1200 r/min engine speed. During the experiments, oil samples were periodically taken from the engine oil and later analyzed. Emissions and temperatures before and after the diesel oxidation catalyst were also measured. The fuels studied were fossil EN590:2013 diesel fuel, 30 vol.% biodiesel (fatty acid methyl ester) and 30 vol.% hydrotreated vegetable oil, which is a paraffinic diesel fuel fulfilling the EN15940 specification. The novelty of the study is based on two parts. First, similar late post-injection tests were run with blends of both hydrotreated vegetable oil and fatty acid methyl ester, giving a rare comparison with the fuels. Second, oil dilution and the fuel exit rates during normal mode without the late post-injections were measured. The results showed the oil dilution and the diesel oxidation catalyst performance to be very similar with regular diesel and hydrotreated vegetable oil blend. With the fatty acid methyl ester blend, increased oil dilution, smaller temperature rise in the diesel oxidation catalyst and higher emissions were measured. This indicates that during diesel particulate filter regeneration by late post-injections, fatty acid methyl ester blends increase fuel consumption and require shorter oil change intervals, while hydrotreated vegetable oil blends require no parameter changes.