Transportation industry is facing a growing challenge to reduce its carbon footprint and utilize the carbon neutral, more environmentally sustainable fuels to comply with the goal of carbon neutrality. Implementation of carbon free fuels such as Hydrogen, Ammonia and low carbon fuels such as Methanol, Ethanol can significantly reduce the greenhouse gas emissions, but these fuels are suitable for SI engine architecture due to their high-octane ratings. Hydrotreated Vegetable Oil (HVO) is one of the few fuel solutions available today with a high Cetane rating (70-80), that can be used as a drop-in fuel in the existing CI engines, with minimal modifications. The main constituent of HVO is pure alkane and it can be produced from feedstocks such as vegetable oils, animal fats, various wastes and by-products. A closed cycle 3-D CFD combustion simulation using a detailed chemistry-based solver has been conducted with the HVO, on a three cylinder, naturally aspirated water-cooled CI engine at its full load, rated rpm. Chemical kinetics file with 92 species and 1240 reactions has been used as a surrogate for the HVO to conduct the combustion simulation. The peak firing pressure has been observed to be lower by 3% and SoC is advanced by 2o CA for HVO as compared to the baseline diesel. HVO combustion manifests the same thermal efficiency with respect to its diesel counterpart. Soot emission has been 36% lower for HVO due to the absence of unsaturated hydrocarbons and the NOx emission is lowered by 32% for HVO, as a consequence of a lowered in-cylinder temperature. Simultaneously, a 13% reduction in CO, 77% reduction in UHC and 74% reduction in VOC have been observed for HVO as compared to diesel. A meticulous monitoring of unregulated emissions proves that the HVO exhaust is devoid of their presence. The 3D CFD combustion exploration unveils that the HVO indeed holds the potential to be a promising drop-in alternate fuel for the next generation CI engines.

Identification of renewable and sustainable energy solutions remains a key focus area for the engine designers of the modern world. An avenue of research and development is being vastly dedicated to propelling engines using alternate fuels. The chemistry of these alternate fuels is in general much simpler than fossil fuels, like diesel and gasoline. One such promising and easily available alternate fuel is compressed natural gas (CNG). In this work, a 3-cylinder, 3-liter naturally aspirated air-cooled diesel engine from the off-highway tractor application is converted into a CNG Diesel Dual fuel (CNG-DDF) engine. Part throttle performance test shows the higher NMHC and CO emissions in CNG-DDF mode which have been controlled by an oxidation catalyst in C1 8-mode emission test. A comparative performance shows that the thermal efficiency is up to 2% lower with CNG-DDF with respect to diesel. However, it has shown the benefit of 44% in Particulate Matter, while retaining the same NOx + NMHC levels as the baseline diesel engine. The cycle average CO emission has been found to increase by 6%. Average exhaust gas temperature has been found to be lower by up-to 54°C with CNG-DDF. To control the particulate and HC levels of the baseline NA engine, the CNG injection has been confined from 20% to 85% engine loads, across all engine speeds. The peak firing pressure and in-cylinder temperature are lower by ~3% and ~7%, and the SoC got retarded by max 4°CA with CNG-DDF which is in-agreement with drop in thermal efficiency. The outcome from the engine dyno level testing has been successfully validated through the tractor testing.

To fulfil the global aspiration of achieving net-zero emissions, hydrogen as a fuel seems to be one of the promising candidates. High energy density per unit mass and zero carbonaceous emissions are the two salient advantages that hydrogen offers. In the present study, a set of detailed chemistry-based 3D CFD combustion simulation has been carried on a 3-cylinder turbocharged, water-cooled port fuel injection SI Hydrogen engine to understand its optimum air–fuel ratio, compression ratio, spark timing and combustion chamber geometry. The simulations have been conducted at the full load of the rated power and maximum torque engine rpms. During simulation, the λ zone for study is restricted between 2.1 and 2.7. Two different bowl geometries (spherical and cylindrical), with two compression ratio options (12 and 14) are explored in the simulations. While the spherical bowl seems to accommodate flame front better than the cylindrical bowl, the compression ratio of 12 is a safer choice to control the maximum rate of pressure rise (dp/dθ). At full load and rated speed, the indicated thermal efficiency drops by 7.7% as the λ swings from 2.1 to 2.7, whereas the indicated specific NOx and dp/dθ drop by 99% and 81%, respectively. Similarly, at full load and maximum torque RPM, the indicated thermal efficiency drops by 6.4% with λ swing from 2.1 to 2.7, whereas the indicated specific NOx and dp/dθ drop by 99% and 91%, respectively. Beyond λ = 2.4 NOx reaches almost to zero, however, at a compromise of the thermal efficiency. The dp/dθ remains well within the acceptable limit under this scenario. To account this trade-off between the performance and emission parameters, optimum λ zone has been found out to be between 2.3 and 2.5.

Cylinder Deactivation technology is explored as an effective mechanism for enhancing the fuel economy and reducing emissions in internal combustion engines. The current exercise focuses upon the feasibility of Cylinder Deactivation technology in a 3-cylinder, 3.3-liter naturally aspirated, water-cooled diesel engine from the off-highway tractor application. A meticulous 1D thermodynamic simulation with individual cylinders deactivated one by one, has proved that deactivating the second cylinder yields the most favorable fuel economy, emissions and engine balancing, particularly at the loads lower than 54% and across all engine speeds. Upon deactivating the cylinders at Top Dead Centre (TDC) and Bottom Dead Centre (BDC), it has been concluded that the most effective deactivation point occurs at TDC, where the minimum air mass is trapped inside the cylinder. This results in a reduction of pumping and friction losses by maximum 34% and an increase in brake thermal efficiency by maximum 26%, as compared to the baseline engine. The in-cylinder trapped A/F ratio becomes richer by 32% when a cylinder is deactivated. As a consequence, the C1-8 mode NRSC cycle average HC and CO reduce by 22% and 28%, respectively. CO2, NOx and PM remains almost the same with respect to the baseline engine (variation less than 3%). The maximum increase in exhaust temperature when mid cylinder deactivated is observed 109°C. These observations are duly validated through the engine dynamometer testing.

Air suction in a naturally aspirated engine is a crucial influencing parameter to dictate the specific fuel consumption and emissions. For a multi-cylinder engine, a turbocharger can well address this issue. However, due to the lack of availability of continuous exhaust energy pulses, in a single or two-cylinder engine, the usage of turbocharger is not recommended. A supercharger solution comes handy in this regard for a single or two-cylinder engine. In this exercise, we explore the possibility of the usage of a positive displacement type supercharger, to enhance the air flow rate of a single cylinder, naturally aspirated, diesel engine for genset application, operating at 1500 rpm. The supercharger parametric 3D CAD model has been prepared in Creo, with three design parameters i.e. (a) Generating radius, (b) depth of blower and (c) clearance between lobes & lobe and casing. The optimum roots blower design is expected to fulfil the target boost pressure, power consumption and hydraulic efficiency requirements. The baseline DoE using Sobol algorithm generates 28 designs, which has been simulated using the Ansys CFX software via modeFRONTIER process automation. A sensitivity analysis of the input variables on the response variables establishes that generating radius is the most dominant parameter influencing the pressure, efficiency and power consumption. A detailed Response Surface analysis using 12 different algorithms showed that, Anisotropic Kriging captures the pressure variable accurately, while Gaussian Process captures the efficiency and power consumption with the best accuracy as per R-squared comparison. A virtual optimization conducted using the favorite RSMs using the MOGA algorithm generated an optimum roots blower design which complies all the constraints for pressure, efficiency and power. RSM optimized design is further validated in the CFX software, and the results for response variables are accurate within 6% error margin.

Ethanol, being a bio-based alternate fuel, is one of the most promising fuels for blending with diesel for emissions reduction, primarily due to its oxygenated nature, which results in lower carbon content than diesel. Under this research work, various ethanol-diesel (ED) blends have been developed for investigation. Additives were developed to address the problem of corrosion, cetane number reduction, and blend stability. A detailed physico-chemical characterization was performed, and all the blends were subjected to the stability test at various temperatures. Subsequently, detailed experiments were conducted to understand ethanol- blended diesel fuels combustion and engine-out emission characteristics. The performance of the tested engine with ethanol blending remained at par with the baseline diesel; however, a reduction in the PM and gaseous emissions established ethanol blend as a favourable fuel solution for the tested CI engine. Experimental results indicate that blending ethanol in diesel leads to 7% reduction of the cycle NOx emissions (for 20% blend) as compared to the baseline diesel; however, HC and CO were observed to have an increasing trend. A significant reduction of PM (~32%) was observed with 20% ethanol blending. The thermal efficiency improved by 6% maximum with 20% ethanol blend at full load. A meticulous analysis of the combustion data indicated no significant change in the engine in-cylinder pressure values and the start of injection from baseline diesel to ethanol blends at full load condition. However, at part load operation (at and below 50% load), peak firing pressure was reduced up to 6%, and the start of injection and combustion got retarded by ~2 deg crank angle. 5% ethanol blend came out as optimum for quick implementation in the existing engine perspective. Nonetheless the additional HC/CO emissions might have to be dealt with by a catalytic converter.

This study eveluates using dimethyl ether (DME) fuelled engine for marching towards zero soot and particulate matter (PM) emissions in the agricultural sector. Comparative emissions and particulate characteristics were analysed for a customised DME-fuelled engine and an unmodified baseline diesel engine. The experimental investigations were performed on a multi-cylinder tractor engine using a dedicated DME fuel injection equipment (FIE) and an unmodified diesel FIE. Regulated emissions, namely carbon monoxide (CO), hydrocarbons (HC), and oxides of nitrogen (NOx), smoke opacity, and particulates were measured at three engine speeds (1200, 1600 and 2000 rpm) and five loads (1.29, 2.59, 3.88, 5.18, and 6.47 bar BMEP). The static fuel injection timing for both test fuels was maintained constant; however, the actual injection timing could be slightly different for both test fuels because of their different physicochemical properties. DME-fuelled engine exhibited relatively higher HC and CO emissions than diesel at low loads; however, both test fuels exhibited nearly identical emissions at higher loads. NOx emissions were lower for DME-fuelled engine than baseline diesel, and its smoke opacity was also negligible at all engine loads and speeds. The particulate number concentration for DME-fuelled engines was much lower than baseline diesel at all test conditions, except 1.29 bar BMEP. Particulate emissions from DME-fuelled engine were mainly in the form of nanoparticles and nucleation mode particles, with negligible numbers of accumulation mode particles. This experimental study demonstrated that DME-fuelling of the tractor engine reduced emissions and it can be used as a sustainable and greener fuel to develop cleaner engines for agriculture/ transport sectors.

Spray investigations are critical for understanding internal combustion engine combustion. Optimised spray atomisation helps improve engine output/performance and reduce tailpipe emissions. The spray from the injector nozzle depends on nozzle hole diameter, fuel injection pressure, ambient density, pressure and temperature in the spray chamber, and test fuel properties. This study evaluated macroscopic and microscopic spray characteristics of dimethyl ether (DME) and baseline diesel under atmospheric conditions (1.013 bar pressure at 298 K temperature). It correlated the spray parameters with distinctive physicochemical properties of diesel and DME using dimensionless numbers, namely Reynolds number, Weber number, and Ohnesorge number. The fuel injection system consisted of a high-pressure mechanical injection pump and mechanical fuel injectors having an original equipment manufacturer fixed nozzle opening pressure in the constant volume spray chamber. The microscopic spray investigations were performed using a phase Doppler interferometer along the spray direction at three axial distances (50, 70, and 90 mm) from the nozzle. The three orthogonal spray droplet velocities of diesel and DME were compared. The droplet number-size distributions for baseline diesel and DME were compared. Macroscopic spray characteristics were evaluated using high-speed imaging. Reynolds number was higher for DME, leading to more turbulence in the spray and accelerating the spray breakup phenomenon. Weber number of DME was also much higher than baseline diesel due to its lower surface tension. The higher Weber and lower Ohnesorge numbers justified the finer droplets of DME sprays. DME showed superior spray atomization characteristics than baseline diesel, leading to superior fuel–air mixing and efficient and sootless combustion.

Combustion in dimethyl-ether (DME)-fueled engines needs to be assessed carefully for its widespread acceptability from a drivability viewpoint. Since the test engine used in an off-highway segment, it was tested in a steady-state cycle for engine performance, combustion, emissions, and their cyclic variations, which were the only parameters to assess the drivability. This study investigated and analyzed the cyclic variations of a 100% DME-fueled engine equipped with modified mechanical fuel injection equipment. It was compared with baseline diesel to understand its positive and negative aspects. Experiments were conducted at different engine speeds (1200,1600, and 2000 rpm) and loads (No Load, 1.29, 2.59, 3.88, 5.18, and 6.47 bar brake mean effective pressure (BMEP)) . In-cylinder pressure was recorded for 250 consecutive engine cycles, and many combustion parameters were comparatively analyzed for diesel and DME fuelings. The coefficient of variation (COV) of maximum in-cylinder pressure (Pmax) was lower for DME than diesel at 1600 rpm and comparable at the other remaining engine speeds (1200 and 2000 rpm). Variations in COV of Pmax were higher at low loads and negligible at high loads for both test fuels. At 2000 rpm, the crank angle positions at which Pmax occurred were distributed in a narrow range for DME, representing higher combustion stability than baseline diesel. Variations in the maximum rate of pressure rise (RoPRmax) were lower for DME at 3.88 and 6.47 bar BMEP, while these were higher at 1.29 bar BMEP than baseline diesel. COV of indicated mean effective pressure (COVIMEP) decreased from lower to higher loads for diesel and DME fueling at 1600 and 2000 rpm engine speeds. The differences in COVIMEP between diesel and DME were negligible at higher loads, representing engine stability similar to baseline diesel. Combustion parameters assessed indicated that DME fueling led to lower cyclic variations than baseline diesel as the engine operated from lower to higher loads. At lower loads, DME fueling showed higher cyclic variations than baseline diesel.

In this study, a dedicated fuel injection equipment (FIE) for a 100% dimethyl ether (DME)-fueled three-cylinder engine was developed. DME has a cetane number (>55) higher than baseline diesel (40-50), making it a promising compression ignition (CI) engine fuel. However, some physicochemical properties of DME, namely lubricity, viscosity, density, calorific value, vapour pressure, incompatibility with elastomers, etc., necessitate modifications in the existing FIE to deliver a power output equivalent to baseline diesel fuelled engine. Modi-fications included customized DME storage tanks, supply lines, return lines, and a pneumatic pre-supply feed pump. In addition, a customized high-pressure pump (HPP) (inline mechanical pump) and a set of modified injectors with larger nozzle hole diameters were used for the DME engine. The engine speed was varied from 1000 to 2000 rpm, and off-road operating conditions were simulated using a non-road steady cycle (NRSC). A detailed evaluation of the FIE for its comparative combustion, performance, and emissions characteristics of DME was conducted vis-`a-vis baseline diesel. The DME-fuelled engine showed an increase of-4.7% in brake thermal efficiency (BTE) under full load conditions and an increase of-8.32% BTE under simulated non-road-testing conditions. In addition, the DME-fuelled engine exhibited no visible smoke and negligible soot in the engine exhaust. DME combustion reduced HC emissions by-50% at low and medium engine speeds, and a-100% reduction was seen at higher engine speeds compared to baseline diesel engine. The CO emission decreased by-90%, and the CO2 emissions were-15% lower for DME. Lower exhaust gas temperature (EGT) and lower heat release rate (HRR) during premixed combustion indicated that DME-fuelled engine acted as a low heat rejection (LHR) engine. This study demonstrated a 100% DME-fueled engine with a customized FIE, delivering higher thermal efficiency and lower emissions than conventional diesel engines for on-and off-road applications.

The Methanol Economy is projected as a sustainable solution to the impending global energy crisis. Methanol and Dimethyl Ether (DME) are projected as exceptional alternative fuel solutions to power future mobility, ensuring the continued growth of internal combustion engines (ICEs) in an environmentally sustainable manner. In this study, the technical feasibility of DME as an alternative to diesel is assessed using a three-dimensional computational fluid dynamics (3D-CFD) simulation approach. A novel fuel injection equipment (FIE) is computationally assessed for DME induction into the engine. A water-cooled, naturally-aspirated, compression ignition (CI) engine used for off-highway application is simulated for using DME as a complete replacement of mineral diesel. First, the baseline diesel combustion calibration is done to validate the simulation model using experimental data. For this, a 3D CFD closed-cycle model of a detailed chemistry-based solver is used. Spray characteristics revealed that DME exhibited faster evaporation than diesel, resulting in lesser fuel-rich pockets in the combustion chamber. DME fueled engine is anticipated to be more thermally efficient due to DME combustion's lower turbulence kinetic energy, which reduces gas side heat transfer through the cylinder walls. DME's higher total in-cylinder mass results in a lower swirl momentum and a reduced swirl ratio for the DME. The proposed FIE promotes a superior Mean Effective Injection Pressure (MEIP) and ameliorated spray penetration characteristics. This study provides systematic guidelines for selecting an appropriate FIE for DME, with Nozzle Through Flow (NTF) and MEIP tuned to achieve the best possible spray characteristics to develop an efficient and clean combustion system for the given application.

Dimethyl Ether (DME) has emerged as a suitable alternative fuel for compression ignition (CI) engines. It is expected to be substitute fossil diesel on a large scale due to its favourable combustion characteristics and sustainable production. This study evaluates the combustion and emission characteristics of a 3-cylinder, water-cooled CI engine fuelled by DME for off-road vehicles, typically used in the agriculture sector. A detailed-chemistry based 3D CFD software is used for simulations in this study. The findings indicate that the baseline diesel fuel injection equipment (FIE), when used for DME injection, is inadequate to match the reference diesel engine performance. Therefore several modified configurations are evaluated in this study using a simulation approach. Modified fuel injection equipment (FIE) significantly reduced the emissions of NOx, soot, UHC, CO and VOC without compromising the base engine power generation. Due to the lower ignition delay of DME, the observed start of ignition advanced. It led to a lower peak firing temperature than its diesel counterpart. The lower cooling loss ratio of the DME engine established its potential as a low-heat-rejection engine. The lower calorific value of DME leads to a 50% increase in the specific fuel consumption than diesel. However, these two fuels seem to be similar on a specific energy consumption basis. A comprehensive study of the un-regulated emission species such as formaldehyde (CH2O), hydrogen peroxide (H2O2), methane (CH4), ethylene (C2H4), and acetylene (C2H2) indicate that DME combustion results in lower unregulated emissions than baseline diesel. A higher number of nozzle holes and an increased mean effective injection pressure (MEIP) of the FIE generate a conducive environment exhibiting superior engine performance and reduced emissions. However, the study identifies a few aberrations in the operating conditions, which show deteriorated emission trends, which should be avoided during the physical engine testing on DME. This study showcases the tremendous potential of an oxygenated fuel such as DME to facilitate the emergence of thermally efficient and cleaner engines, with very low regulated and unregulated emissions, indicating their future for off-highway vehicles.

Prediction of combustion system performance in the design stage via simulation tools can facilitate the reduction of iterations in the testing stage. Simulation tools can be used not only to predict the overall system performance for a certain set of hardware but can also be used to optimize the hardware. In this work, we intend to demonstrate the approach of Response Surface Modeling (RSM) to optimize the geometries of combustion systems from a performance and emission perspective. The Gaussian Process RSM algorithm, supplemented by Uniform Latin Hypercube (ULH) and Incremental Space Filler (ISF) Design of Experiment (DOE), has been used to arrive at an optimized piston bowl geometry for a Direct Injection (DI) diesel engine, having the potential to perform well both at the rated power and maximum torque operating points. Three principal piston bowl parameters have been identified for optimizing the geometry: (a) Bowl diameter, (b) Bowl depth, and (c) Bowl angle. A sensitivity analysis shows the bowl diameter to be the dominant geometry parameter in influencing the Indicated Mean Effective Pressure (IMEP) of the engine. The IMEP increases with a reduced bowl diameter, but at the expense of increased oxides of nitrogen (NOx). Within our parameter range of investigation, bowl depth was observed to be less influential than the bowl diameter, and the bowl angle was found to be the least influential of the three parameters in affecting the engine performance. Due to the strong nonlinearity of the combustion problem, the generated three-dimensional (3D) RSM surface manifested an intricate shape, highlighting the importance of an appropriate algorithm selection to minimize the prediction error. In the end, the competency of the parallel coordinate chart has been shown to prove it as a smart and elegant tool for a multi-objective optimization problem.

The application of virtual simulation of engine components has become an integral part of design and development process. Virtual simulation offers opportunities to reduce number of physical tests during design verification and validation. The accuracy of virtual simulation is also dependent on applying accurate boundary conditions like material properties and load acting on components. Accurate simulated model helps in achieving considerable reduction in development time and cost.This paper explains a design methodology of connecting rod assembly for new engine family having shorter stroke. The adopted methodology simulates major loading conditions for Compressive, tensile stresses & fatigue life of connecting rod. Finite element analysis was done to calculate static displacement, strain and stresses under maximum compressive and tensile loading which were then used for critical point evaluation. Fatigue analysis and longevity is assessed through ANSYS. To validate the methodology developed; accelerated physical fatigue testing was carried out on the rig and results were compared. A very close correlation could be established between FEM results and failure point on physical test samples. The strain values predicted through simulation is within 10% of error with measured strain values. This calibrated model helped us to set appropriate design factor of safety for such applications.