Piston Bowl Research Articles

Experimental study on the effect of piston bowl geometry on the combustion performance and pollutant emissions of methane-diesel common rail dual-fuel engine

In dual-fuel operations, high methane substitution negatively affects combustion performance and creates high hydrocarbon (HC) and carbon monoxide (CO) pollutant emissions. Piston bowl geometry is proven an effective method for improving combustion performance and emissions. In the available study, combustion chamber geometry is experimentally indicated to succeed in dramatically reducing HC and CO pollutant emissions uncompromising nitrogen monoxide (NO) and smoke pollutant emissions.In this study, the effect of piston bowl geometry on the combustion performance and pollutant emissions of a single-cylinder methane-diesel common rail dual-fuel engine was studied experimentally. High-performance piston bowl geometries (Toroidal and Toroidal re-entrant) of conventional diesel operations were used versus original combustion chamber (OCC) geometry in diesel and dual fuel operation for enhancing combustion performance and reducing pollutant emissions. The experiments were conducted at constant 1850 r/min and five different engine loads. The methane energy fraction was set to 50% of the total energy fraction in dual fuel operations. Experimental results showed that the Toroidal re-entrant combustion chamber (TRCC) geometry reduced the long ignition delay period that was due to the methane addition and ensured more stable combustion at all torque conditions. In dual fuel operation, the TRCC geometry improved smoke, HC, and CO pollutant emissions by an average of 18%, 10%, and 3% for all loads, respectively, compared to the OCC geometry. However, NO pollutant emissions were an average of 2.5% higher than OCC geometry for the TRCC geometry. In sum, use of the TRCC geometry is an effective way for providing more complete combustion and reducing emissions under dual fuel operations at all torque conditions between 3 and 9 Nm.

A CFD Study on the Effects of Injection Timing and Spray Inclusion Angle on Performance and Emission Characteristics of a DI Diesel Engine Operating in Diffusion-Controlled and PCCI Modes of Combustion

In three-dimensional (3D) computational fluid dynamics (CFD) simulations, the effects of injection timing and spray inclusion angle (SIA) on performance and emissions of diffusion-controlled and Premixed Charge Compression Ignition (PCCI) combustion in part load for a heavy-duty direct injection (HDDI) diesel engine are studied. The start of injection (SOI) of a 146° SIA injector is varied between −70 and −10 °crank angle (°CA) after top dead center (ATDC). For −50 °CA ATDC SOI with various SIAs between 80° and 146°, PCCI combustion reduces mono-nitrogen oxide (NOx) emissions significantly compared to conventional diesel combustion (CDC). Due to incomplete combustion in rich zones formed by droplet–cylinder wall interaction, early wide SIA injection deteriorates combustion efficiency (CE) and Indicated Mean Effective Pressure (IMEP) and increases soot and carbon monoxide (CO) emissions. Narrow-angle sprays interacting with the piston bowl elevate CE and IMEP and decrease soot and CO emissions but increases NOx emissions. Optimal combustion is achieved by avoiding fuel droplet–cylinder wall interaction. By spray-targeting at the stepped lip of the piston bowl, 100° SIA and −50 °CA ATDC SOI yield, respectively, the highest CE and IMEP: 97.8% and 3.37 bar and the lowest soot and CO emissions: 33.5 and 2.2 ppm, with acceptable NOx emissions.

Application of micro-genetic algorithms to optimize piston bowl geometries for heavy-duty engines running on diesel and 1-Octanol fuels

This study presents the developments in piston bowl geometry and renewable fuels for a heavy-duty diesel engine to approach the CO2 emission targets set by the European Union. 3D computational fluid dynamics were performed within the framework of a micro-genetic algorithm which was used as a global optimization method to evolve piston bowl geometries. Furthermore, this paper discusses using 1-Octanol as a renewable substitute for fossil diesel fuel. 1-Octanol’s oxygenated nature and straight-chain structure demonstrate high potential in improving combustion and engine efficiency.The results of the numerical investigations show that the optimized piston bowl geometry from a micro-genetic algorithm for diesel fuel improved the indicated specific fuel consumption and reduced indicated specific CO2 emissions by up to ∼5% and ∼2% respectively. This is achieved due to improved air utilization with the optimized piston bowl geometry. The optimized piston bowl geometry results in increased air utilization in the squish region and reduced loss in spray movement due to bowl design. 1-Octanol as fuel demonstrates up to ∼1.8% increase in indicated thermal efficiency and ∼2% reduction in indicated specific CO2 emissions when compared to diesel fuel for base piston bowl shape. The oxygen content and lower C / H ratio in 1-Octanol fuel lead to faster and improved combustion, which helps increase indicated thermal efficiency compared to diesel fuel. The diesel-optimized piston bowls for 1-Octanol show minor improvement in fuel consumption, air utilization, and emissions.

Computational assessment of the effects of pre-chamber and piston geometries on the combustion characteristics of an optical pre-chamber engine

Pre-chamber combustion (PCC) has the potential to extend the lean-burn limit in spark-ignition engines, which can promote engine efficiency and relieve the concern of emissions of nitrogen oxides. This work assessed the effects of pre-chamber (PC) and piston geometries on the combustion characteristics of an optical methane PCC engine with both experimental and computational approaches. Five active-type PCs with different volumes and nozzle diameters (12 nozzles distributed evenly in two layers) and two pistons (bowl and flat) were tested under lean-burn conditions. Multi-cycle pressure and heat release profiles, natural flame luminosity images, and OH* chemiluminescence images were measured and employed for CFD modeling validations. The PCs with the smaller nozzle diameter yielded more intensely-reacting jets from the upper layer of nozzles compared to the other PCs, attributed to the stronger gas choke there, which dramatically affected the flow fields. A larger PC volume allowed more air–fuel mixture to be trapped within the PC whose combustion then resulted in faster pressure buildup, which, however, led to higher heat transfer loss. Compared to the bowl piston, the flat piston generated a higher heat release rate during the late combustion period owing to the relatively longer jet propagation within the squish region.

Thermodynamic Performance of an Engine by Modifying Piston Bowl Geometries Fuelled by SME-100, LA-100, KB-100 Biodiesel Blends, and Diesel

Simulation of Direct injection (DI) compressed ignition (CI) engine working on diesel thermodynamic cycle on diesel-Rk software carried out for evaluating the effect on thermal performance. The analysis of an engine was worked out by applying different bowl geometrical shapes and by testing with different fuels. Further same compositions were tested on an experimental test rig having a set-up of (compressed ignition, single cylinder, four strokes, air-cooled, direct injection) diesel engine at constant crank speed. Hemispherical (HCC), Shallow depth (SCC), Re-entrant (RCC), Double wedge shallow, and Toroidal (TCC) piston geometries were created in solid-work and analyzed with B-100 blend of SME (Soybean Methyl Ester), KB (Karanja Biodiesel), LA (Roselle Biodiesel) and diesel further they were analyzed and their effects have investigated experimentally and numerically at fully loaded condition, with a constant crank speed of 1500 rpm and by setting constant compression ratio at 17.5. BSFCs were higher by 21.03%, 12.97%, and 12.96% for SME100, KB100, and LA100 with hemispherical, toroidal, and re-entrant type combustion chambers compared with the diesel fuel. Indicated thermal efficiencies and ignition delay periods were reported slightly lower for different blends and pure biodiesel than diesel at specific load conditions whereas combustion durations were reported higher compared to diesel.

Withdrawn: Investigating the Role of Fuel Injection Pressure and Piston Bowl Geometries to Enhance Performance and Emission Characteristics of Hydrogen‐Enriched Diesel/1‐Pentanol Fuelled in CRDI Diesel Engine

The above article from Heat Transfer, published online on 5 December 2022, on Wiley Online Library (https://onlinelibrary.wiley.com/doi/abs/10.1002/htj.22448), has been withdrawn by agreement between the authors, the journal Editor in Chief William M. Worek and Wiley Periodicals LLC.The withdrawal has been agreed due to a technical error at the publisher that caused the article to be mistakenly published online although its publication had been cancelled at the request of the authors.

Development and Validation of a CFD Combustion Model for Natural Gas Engines Operating with Different Piston Bowls

Nowadays, an accurate and precise description of the combustion phase is essential in spark-ignition (SI) engines to drastically reduce pollutant and greenhouse gas (GHG) emissions and increase thermal efficiency. To this end, computational fluid dynamics (CFD) can be used to study the different phenomena involved, such as the ignition of the charge, combustion development, and pollutant formation. In this work, a validation of a CFD methodology based on the flame area model (FAM) was carried out to model the combustion process in light-duty SI engines fueled with natural gas. A simplified spherical kernel approach was used to model the ignition phase, whereas turbulent flame propagation was described through two variables. A zero-dimensional evolution of the flame kernel radius was used in combination with the Herweg and Maly formulation to take the laminar-to-turbulent flame transition into account. To estimate the chemical composition of burnt gas, two different approaches were considered—one was based on tabulated kinetics, and the other was based on chemical equilibrium. Assessment of the combustion model was first performed by using different operating points of a light-duty SI engine fueled with natural gas and by using the original piston. The results were validated by using experimental data on the in-cylinder pressure, apparent heat release rate, and pollutant emissions. Afterward, two other different piston bowl geometries were investigated to study the main differences between one solution and the others. The results showed that no important improvements in terms of combustion efficiency were obtained by using the new piston bowl shapes, which was mainly due to the very low (+4%) or null increase in turbulent kinetic energy during the compression stroke and due to the higher heat losses (+20%) associated with the increased surface area of the new piston geometries.

Effect of piston geometry on combustion characteristics of CI engine used Sal seed oil

The effect of piston bowl geometry on reducing soot emissions, improving combustion, and in-cylinder flow movements in a direct injection diesel engine was investigated. Standard combustion chamber (SCC) and newly modified combustion chamber (MCC) geometries were compared at the same compression ratio (17.5:1). Experimental analysis of diesel engines is expensive and time consuming, and therefore the Computational Fluid Dynamics program was used to analyze the combustion, flow and emission process. AVL Fire ESE Diesel software was used in the numerical study. The numerical work was compared with the experimental results, and it was validated. In addition, 10% biodiesel mixture (10% Sal seed oil methyl ester + 90% diesel fuel) and diesel fuel were used in the analysis. These fuels and two different bowl geometries were investigated at 2000 rpm and full load conditions. Thus, the effect of the used biodiesel fuel and the developed bowl geometry were investigated. Sal seed oil methyl ester was used as biodiesel fuel. The results show that higher turbulence velocity distribution, better mixture fraction values and lower soot formation distribution are obtained by directing the MCC type fuel according to SCC type. When the pressure, temperature and heat release in the combustion chamber are examined, the highest values were obtained with B10 blended fuel used at the SCC type combustion chamber. The maximum heat release rates are 8.72, 9.38, 8.21, and 9.30 J/° for SCCD100, SCCB10, MCCD100 and MCCB10 fuels, respectively.

Effects of Piston Bowl Geometry on Combustion and Emissions of a Four-Stroke Heavy-Duty Diesel Marine Engine

Piston bowl geometry plays an important role in the fuel/air mixing quality which has a direct influence on the performance and emission characteristics of the engine. This work studied the effects of piston bowl geometry on the combustion and emissions of a four-stroke direct injection (DI) heavy-duty diesel marine engine. Three types of piston bowls with various parameters were numerically investigated, targeting to improve engine performance, fuel oil consumption, and emission characteristics. The results pointed out that the ω-type and re-entrant piston bowls enhanced cylinder power by 1.26% and 2.67% while reducing the indicated specific fuel oil consumption (ISFOC) of the engine by 1.06% and 1.60%, respectively, compared to the U-type bowl. Especially, the ω-type and re-entrant piston bowls reduced NO (nitric oxide) emission by up to 25.61% and 46.09%, respectively, owing to lower peak temperatures in comparison to the U-type piston bowl. The results also pointed out that changing the piston bowl type has negligible effects on the engine-out soot and CO2 emission characteristics of the engine. Based on this study, it is highly recommended to utilize the re-entrant piston bowl for four-stroke DI diesel engines to improve both engine performance and fuel oil consumption while reducing NO emission simultaneously.

Piston bowl shape and biodiesel fuel effects on combustion and emission of diesel engines

This study aims to investigate the effects of piston bowl shape and biodiesel fuel on combustion and emissions of a direct injection (DI) diesel engine. Three configurations of piston bowl geometry are modeled: hemispherical, toroidal, and rectangular. Biodiesel fuel derived from soybean oil is being considered. An experimental work was conducted on a diesel engine with a hemispherical piston bowl, and a better validity was attained. The study showed that, diesel engine with toroidal piston bowl delivered the largest power than other shapes, where turbulent regions are formed inside the toroidal piston bowl with higher intensity, which resulted in better combustion characteristics and lower emission concentrations. It is observed from the combustion of biodiesel fuel that, the rapid combustion stage began earlier than conventional diesel fuel by about 5o CA, heat release rate (HRR) decreased by 18.88%, emissions of carbon monoxide (CO), and unburnt hydrocarbon (UHC) reduced but nitric oxide (NO) emission increased by about 17.78% at 55o CA, as compared to diesel fuel. During the injection process, the jet core of biodiesel fuel appeared thicker and longer than conventional diesel fuel. For optimization, preheating with exhaust gas recirculation (EGR) of biodiesel fuel contributes to reduce the emissions of nitrogen oxides (NOx) and improve the atomization rate.

Combustion Modeling Approach for the Optimization of a Temperature Controlled Reactivity Compression Ignition Engine Fueled with Iso-Octane

In this study, an innovative Low Temperature Combustion (LTC) system named Temperature Controlled Reactivity Compression Ignition (TCRCI) is presented, and a numerical optimization of the hardware and the operating parameters is proposed. The studied combustion system aims to reduce the complexity of the Reaction Controlled Compression Ignition engine (RCCI), replacing the direct injection of high reactivity fuel with a heated injection of low reactivity fuel. The combustion system at the actual state of development is presented, and its characteristics are discussed. Hence, it is clear that the performances are highly limited by the actual diesel-derived hardware, and a dedicated model must be designed to progress in the development of this technology. A Computational Fluid Dynamics (CFD) model suitable for the simulation of this type of combustion is proposed, and it is validated with the available experimental operating conditions. The Particle Swarm Optimization (PSO) algorithm was integrated with the Computational Fluid Dynamic (CFD) software to optimize the engine combustion system by means of computational simulation. The operating condition considered has a relatively high load with a fixed fuel mass and compression ratio. The parameters to optimize are the piston bowl geometry, injection parameters and the boosting pressure. The achieved system configuration is characterized by a wider piston bowl and injection angle, and it is able to increase the net efficiency of 3% and to significantly reduce CO emissions from 0.407 to 0.136 mg.

Maximum reduction in greenhouse gas emissions by complete replacement of natural gas with pure hydrogen as a sole low reactive fuel in a RCCI engine

In order to maximum reduction in hydrocarbon fuels consumption as the largest source of greenhouse gas emissions, the aim of this study is to evaluate a RCCI engine performance fueled with diesel fuel and pure hydrogen as sole low reactive fuel. For this purpose, a single-cylinder heavy-duty diesel engine with bathtub piston bowl profile and compression ratio of 14.88:1 is assessed that operates at its mid-load range from 9.4 to 13.5 bar gross IMEPs. In order to overcome the NOx challenge resulted from using pure hydrogen, the use of suitable amount of EGR and nitrogen addition as air-hydrogen diluents along with the advanced SOI timing were employed. The simulation results show that in a hydrogen-fueled RCCI engine, while reducing the diesel fuel energy share as the only supplier of air-hydrogen mixture ignition energy to about 13%, the HES percentage can be enhanced up to 87%. Although, the SOC will occur with a long delay and the CA50 will take place about 15°CA after the TDC compared to the experimental data, however, the maximum loss of the engine load is less than 6% with the GIE of more than 48% without any exposure to diesel knock. Moreover, not only the EURO VI level of the CO and UHC emissions and the EPA level of Formaldehyde emission can be met, but also, the EURO VI level of NOx emission as the most important challenge of a hydrogen-fueled engine is achievable.

Numerical and optical soot characterization through 2-color pyrometry technique for an innovative diesel piston bowl design

The development of innovative diesel piston bowl designs has shown significant improvement of the near-wall flame evolution, resulting in lower fuel consumption and engine-out soot emissions. With this aim, a novel hybrid piston bowl for a 1.6 L light-duty diesel engine was designed, coupling a sharp-stepped bowl and radial-bumps in the inner bowl rim. The effects of the proposed hybrid bowl were analysed through both single-cylinder optical engine and 3D-CFD models, which feature a detailed chemical kinetic mechanism and the Particulate Mimic (PM) soot model. The 2-color pyrometry optical technique was adopted to obtain the optical soot density (KL) and the temperature of the soot surface. Then, a line-of-sight integration of the numerical soot distribution was adopted to obtain a planar KL distribution, which is directly comparable with the experimental KL images. The results showed a good agreement in terms of soot distribution between 3D-CFD and experiments, confirming the high prediction capabilities of the developed numerical methodology. The synergetic application of numerical and optical techniques highlighted that the hybrid bowl strongly mitigates the flame-to-flame interaction with respect to a conventional re-entrant bowl, leading to lower soot formation in the flame collision area. Moreover, faster flame propagation toward the cylinder axis is highlighted with a consequent higher soot oxidation rate in the late combustion phase.

Numerical and experimental investigation of the flow structure in a diesel engine with different piston bowl structure

In this study, unfired (cold) flow application was investigated in a single cylinder die-sel engine with different combustion chamber geometries. In the experimental study, images obtained with the help of an endoscopic camera for different cycle points were instantly detected at constant speed. At the same time, velocity distributions of two dif-ferent combustion chambers for different crank angles were analyzed in Ansys Forte software at before and after TDC. Thus, the flow distributions of different combustion chamber geometries in the chamber were compared. It can be said that regional swirl is formed in the newly developed combustion chamber geometry and develop in the chamber rather than the piston base compared to the standard combustion chamber. In addition, especially during the compression process, the squish movement of the bowl was observed with the movement of the piston. Here, it could be said that the newly de-veloped chamber geometry is more effective than the standard bowl geometry. When the distribution of velocity vectors in the x-y and x-z axis were examined in numerical analysis, especially in the TDC position, it was determined that the interaction of the flow developed by the new bowl geometry with the fuel droplets was more evident. While it is seen that the vector velocity changes are close to each other at the 6920 CA before the fuel injection, it is seen that higher flow velocities are formed for the standard combustion chamber at the 7200 CA where the spraying continues and develops.

Numerical study on the wall-impinging diesel spray soot generation and oxidation in the cylinder under cold-start conditions of a diesel engine

The combustion of wall-impinging diesel spray of heavy-duty diesel engines deteriorates combustion quality under cold-start conditions, making it difficult to control soot emissions. To investigate the causes of soot increase in the combustion of wall-impinging spray at low temperature and low speed starting conditions, the effect of the starting fuel mass on the soot formation and oxidation process was analyzed using a multidimensional computational fluid dynamics (CFD) model. The results show that the diesel spray is guided by the piston wall and the limited space, the spray impinged on the wall and the vapor-phase fuel flowed in the spray interaction zone. Thus, the soot mainly accumulates in the spray interaction zone, the region near the cylinder head and the bowl wall in the combustion chamber bowl. The soot from the vapor of deposited fuel film in the piston bowl wall and near wall region accumulates continuously in the after combustion stage, becoming the main source of soot emissions at the time of exhaust valve opening (EVO). Increasing the mass of starting fuel raises the mass of the rich mixture and wall-impinging fuel, which enhances the mismatch between fuel and air, resulting in higher soot generation, while soot is more difficult to be completely oxidized by OH radicals, and ultimately soot emissions increase significantly. It can be deduced that the engine-optimized injection strategy may mitigate the increase in soot emissions at high start-up fuel injection conditions.

Numerical Investigation of a Dual Fuel Engine Fueled by Diesel-Acetylene and Biodiesel-Acetylene with Modified Piston Bowl Geometry

Numerical Investigation of a Dual Fuel Engine Fueled by Diesel-Acetylene and Biodiesel-Acetylene with Modified Piston Bowl Geometry

Methane slip reduction of conventional dual-fuel natural gas diesel engine using direct fuel injection management and alternative combustion modes

Alternative combustion mode and change of spray geometry show potential for methane slip reduction in a dual fuel diesel-natural gas internal combustion engine. Three combustion regimes are simulated; a conventional diesel methane dual-fuel combustion and two modes of reactivity controlled compression ignition (RCCI) with early (EIRCCI) and late (LIRCCI) injections. Methane is injected as the premixed fuel into the port and diesel as direct-injected fuel in all combustion modes. The start of direct fuel injection (SOI) is used as the combustion management tool, swiping from misfiring to knock limits at part loads.By switching combustion mode from conventional (CDF) to LIRCCI and EIRCCI, methane slip is reduced by 12% and 33%, respectively. SOI is used effectively to manage methane slip in any combustion mode, but the effect is more substantial in the EIRCCI mode.Emission results support methane slip trends’ observations. Nitrogen oxides (NOx) emission is increased in CDF by advancing SOI and decreased in both the LIRCCI and EIRCCI modes. Compared to CDF, late and early injection RCCI modes produce 417% and 67% more soot. Also, results show that high levels of methane slip in CDF can be reduced to some extent without any geometry modification by SOI management.Three diesel spray angles (SAs) of 60, 90, 120° are examined. Minimum methane slip is obtained when the SA is towards the squish area, and maximum methane slip is obtained when the SA is towards the piston bowl. Increasing SA from 60 to 90 and 120° results in a 16.4% and 42.5% reduction of methane slip.

Combined effects of nozzle hole variation and piston bowl geometry modification on performance characteristics of a diesel engine with energy and exergy approach

This experimental work aims to address the challenges of waste management. Biomass waste is converted into useful fuel and considered as a replacement to conventional fuel in CI engines. In this context, the grape marc and grape pomace are crushed and further processed to produce grapeseed oil. The grapeseed oil is further trans esterified to produce grapeseed seed oil methyl ester. The present study aims in examining the effect of varying piston shapes and nozzle profile on energy and exergy rates of a CI engine run with grapeseed oil methyl ester (GSME) blended with cerium oxide nano particles. The CeO2 nano particles were suspended in the base fuel at a concentration of 100 ppm and stability tests were conducted. The experiments were performed on a single cylinder, water cooled diesel engine with rated power of 5.2 kW. The research work includes two additional piston shapes namely, toroidal and shallow deep and two additional nozzle profiles viz. 4 hole and 5-hole nozzle. The hemispherical shape and 3-hole nozzle were considered as the standard one. Energy and exergy analysis were done on the experimental data to understand the exergy associated with cooling water, exhaust gas and unaccounted losses. The energy and exergy rates show that increase in nozzle hole number, decreases the destructive availability of the system. The exergetic efficiency of 32.8% is higher proving that toroidal shape and 5-hole nozzle profile is comparatively better and suitable for effective engine operation. HC, CO and smoke emissions reduced considerably by 14.4%–30% by the engine modification. Brake thermal efficiency was improved from 28.2% to 31.02% for CI engine with biodiesel. The paper addresses the gap in fuel modification clubbed with engine modification using biomass waste derived fuel. Exergy and energy analysis further add value to this current experimental work.

Complex analysis of combustion and emission parameters of bio‐renewable fuel mixtures in dual‐fuel mode

AbstractDual‐fuel mode internal combustion engines need perfect conditions to ignite the mixture of air and fuel without the use of a spark plug. A perfect mixture of fuel and air is essential for the most effective ignition, and this is a technical challenge. Ignition systems have been developed for use in internal combustion engines. Structural aspects of advanced combustion technology engines like compression ratio, exhaust gas recirculation rate, fuel ratio, and piston bowl geometry can influence heat regulation during the combustion process, increase the load range of the engine and reduce the formation of NOx, soot, and other emissions formed during the combustion process. This article shows how such an engine could be constructed. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

The Combined Effect of the Piston Bowl Geometry and Injection Fuel Pressure on the Compression Ignition Engine Characteristics

In this study, the combined effect of the piston bowl geometry and fuel injection pressures on combustion, performance and emission characteristics of compression ignition (CI) engine fueled with baseline Diesel (D100) and microalgae-biodiesel (MA100) was studied. In this paper, the comparison study for the two different piston bowl geometry, namely: hemispherical combustion chamber (HCC) and toroidal re-entrant combustion chamber (TRCC), was carried out with the various fuel injection pressures (200-240 bar) performed. A single-cylinder, direct injection, and four strokes were chosen to simulate the compression ignition (CI) engine by developing a zero-dimensional simulation model using Diesel-RK commercial software. The data was validated by comparing the results against experimental data, which showed that the results obtained from the numerical simulation were in good agreement with the experimental results. MPRR, EGT, HRR, BTE, and NOx exhibited an increase with increased fuel injection pressure, while an inverse trend was observed with ID, CO, and HC. When using MA100 biodiesel with HCC piston bowl geometry at fuel injection pressure (200 bar), the maximum predicted brake specific fuel consumption (BSFC) was 0.545 kg/kWh. A significant reduction of nitrogen (NOx) oxides emissions was also observed with low fuel injection pressures. In contrast, the emission characteristics such as hydrocarbons and CO were enhanced by increasing fuel injection pressure and modifying the piston bowl geometry.