Common Rail Research Articles

The use of dimethyl ether (DME) solution in compression ignition engine

The development of compression ignition combustion engines is focused on meeting many challenges, mainly related to growing ecological requirements. Currently, however, due to technological barriers, meeting them is very difficult and requires the use of additional exhaust gas treatment systems. The use of injection of a diesel and gas solution seems to be very promising. The article presents the results of engine tests involving the use of a solution of diesel fuel and dimethyl ether. The tests were performed on a single-cylinder research engine equipped with a common rail fuel system. The obtained results suggest that the use of the solution has a positive effect on the process of creating the fuel-air mixture, resulting in a reduction in the concentration of HC and CO, while increasing the share of NOx, suggesting an improvement in the combustion process, as evidenced by the limiting injection dose.

Experimental study on diesel spray flame and wall heat transfer of two-dimensional combustion chamber: effect of common rail pressure

Reducing the heat transfer occurring during the spray combustion of diesel engines remains a challenging task. This study investigated the spray flame behaviour, wall heat flux, and heat transfer phenomena of diesel engines at varying common rail pressures. A rapid compression and expansion machine (RCEM) was employed to simulate a single cycle of diesel spray combustion using split injection sprays. The two-dimensional (2D) stepped piston cavity is a uniquely shaped model used to describe the spray flame behaviour in the combustion chamber. To investigate the heat transfer phenomena, we installed wall heat flux sensors in the cylinder and cavity side. The results indicated that higher common rail pressures increased the peak value of the wall heat flux and reduced the combustion duration and the luminous flame. The higher common rail pressure led to an increase in spray velocity, thereby enhancing the turbulence level. This increase in turbulence to higher peak value of the wall heat flux. The highest peak value of the wall heat flux was reached by the cylinder head owing to the intense combustion region, followed by the cavity bottom owing to the highest flame temperature occurring around this location. Additionally, the heat transfer phenomena in diesel engines were successfully represented by local Nu-Re correlations. Our results contribute to the discussion on heat transfer phenomena that influence the thermal efficiency of diesel combustion engines.

Optimizing Fuel Injection Timing for Multiple Injection Using Reinforcement Learning and Functional Mock-up Unit for a Small-bore Diesel Engine

<div>Reinforcement learning (RL) is a computational approach to understanding and automating goal-directed learning and decision-making. The difference from other computational approaches is the emphasis on learning by an agent from direct interaction with its environment to achieve long-term goals [<span>1</span>]. In this work, the RL algorithm was implemented using Python. This then enables the RL algorithm to make decisions to optimize the output from the system and provide real-time adaptation to changes and their retention for future usage. A diesel engine is a complex system where a RL algorithm can address the NO<sub>x</sub>–soot emissions trade-off by controlling fuel injection quantity and timing. This study used RL to optimize the fuel injection timing to get a better NO–soot trade-off for a common rail diesel engine. The diesel engine utilizes a pilot–main and a pilot–main–post-fuel injection strategy. Change of fuel injection quantity was not attempted in this study as the main objective was to demonstrate the use of RL algorithms while maintaining a constant indicated mean effective pressure. A change in fuel quantity has a larger influence on the indicated mean effective pressure than a change in fuel injection timing. The focus of this work was to present a novel methodology of using the 3D combustion data from analysis software in the form of a functional mock-up unit (FMU) and showcasing the implementation of a RL algorithm in Python language to interact with the FMU to reduce the NO and soot emissions by suggesting changes to the main injection timing in a pilot–main and pilot–main–post-injection strategy. RL algorithms identified the operating injection strategy, i.e., main injection timing for a pilot–main and pilot–main–post-injection strategy, reducing NO emissions from 38% to 56% and soot emissions from 10% to 90% for a range of fuel injection strategies.</div>

Energy, exergy, emissions and sustainability assessment of hydrogen supplemented diesel dual fuel turbocharged common rail direct injection diesel engine

The present investigation involves the study of Mahindra & Mahindra Supro BS VI Twin Cylinder Turbocharged CRDI Diesel Engine modified to operate under dual fuel mode utilizing hydrogen as a secondary fuel and neat diesel as a pilot fuel. The tests were carried out at constant speed of 2200 rpm (±20 rpm) under three different loading conditions i.e. BMEP values of 1.38 bar, 3.47 bar and 5.6 bar using H2 enrichment of 0%, 10%, 20%, 30% and 40% respectively along with neat diesel. The performance characteristics of the engine are evaluated using energy-exergy and emissions-based approach along with sustainability studies. The results show that turbocharging significantly improves volumetric and indicated thermal efficiency of engine. At BMEP of 5.6 bar, D + H2 (40%) exhibited highest energy efficiency of 28.94% and exergy efficiency of 28.41% compared to baseline diesel fuel. The irreversibilities due to combustion, mixing, friction and unaccounted reasons was found to be the minimum for D + H2 (40%) at higher BMEP values. Emission analysis revealed that trade-off takes place between nitrogen oxides and smoke opacity (%) with hydrogen substitution to baseline diesel fuel. The sustainability analysis revealed that, D + H2 (40%) has the highest exergy performance coefficient and sustainability index compared to all other cases. From the results, it can be concluded that D + H2 (40%) is the most suitable fuel combination for the Twin Cylinder Turbocharged CRDI Diesel Engine.

Effects of Blended Diesel-Biodiesel Fuel on Emissions of a Common Rail Direct Injection Diesel Engine with Different Exhaust Gas Recirculation Rates.

The aim of the study was to investigate the exhaust gas emissions and fuel consumption of a common rail direct injection (CRDI) diesel engine using mixed diesel (B10) and biodiesel (B20-B100) fuels. The study's primary objective was to determine the effects of blended diesel-biodiesel fuel on CRDI emissions based on different exhaust gas recirculation (EGR) rates, including carbon monoxide (CO), carbon dioxide (CO2), oxygen (O2), nitrogen oxide (NOx), and hydrocarbon (HC) emissions, smoke opacity, exhaust gas temperature, and fuel consumption. The CRDI experiments involved adjusting the different engine speeds (1400-3000 rpm) and EGR rates (0 and 12.5%), which were analyzed to determine their impact on these parameters for both blended diesel and biodiesel fuels. The results showed that under the conditions of no EGR (0%), the CO and HC emissions and the smoke opacity were lower than those with a 12.5% EGR rate for all fuel types and all cases. With 12.5% EGR rate, the O2 emissions and the EGT of the CRDI diesel engine decreased, which resulted in significantly lower NOx emissions because of EGR into the combustion chamber. For the maximum engine speed of 3000 rpm and with no EGR, the CO and HC emissions and the smoke opacity were lower than those with a 12.5% EGR rate for all fuel types. With a 12.5% EGR rate at 3000 rpm, the O2 emissions and the exhaust gas temperature were reduced by 0.07% and 2.27%, respectively, and the NOx emissions were reduced by 2.54%. However, with EGR, the CO and HC emissions and the smoke opacity increased by 7.70%, 18.61%, and 0.4%, respectively. Furthermore, the fuel consumption of pure biodiesel (B100) at 3000 rpm with a 12.5% EGR rate was reduced by 2.81% compared to that with a 0% EGR rate. Because the temperature in the combustion chamber is high enough for the engine to run, the EGR reuses a portion of the exhaust gases and can help to minimize the quantity of fuel in the combustion chamber. As a suggestion based on these observations, biodiesel fuel should not exceed B80 because the viscosity and density of fuel that are too high may affect the fuel injection system, both the injectors, and the pressure pump, causing the injectors to be unable to work correctly. These findings can contribute to the development of strategies and technologies for reducing emissions and improving fuel efficiency in CRDI diesel engines.

Contribution To the Evaluation of Soot Deposit Thickness Evolution and Its Impact on Heat Transfer Within Heavy Diesel Engines: An Innovative Simplistic Procedure

This study deals with a numerical procedure designed and built to evaluate the evolution of soot deposits thickness and their impact on heat transfer for a high-pressure common rail 16V280 marine diesel engine piston. Using a combination of 3D numerical computations and an iterative calculation algorithm, this work reveals the complex relationship between soot deposit, temperature distribution, and piston thermal dynamics. Non-uniform soot deposit distribution is observed, concentrated at the piston bowl peripheral regions. This distribution aligns with theoretical expectations, indicating the influence of the swirl effect. The presence of soot deposits alters the temperature distribution, implying displacement of high-temperature zones towards the bowl region of the piston. The reduction in surface temperature of approximately 14%, is attributed to the lower heat transfer coefficient of deposited layers. This greatly influences the distribution of thermo-mechanical stresses of the piston. The proposed procedure offers an approach to assess the impact of soot deposit on heat transfer. In addition, this study contributes to a better understanding of realistic piston conditions and addresses the challenges introduced by soot deposits in heavy-duty diesel engines by combining the proposed procedure with investigations based on CFD software tools.

Screening nano additives for favorable NOx/smoke emissions trade-off in a CRDI diesel engine fueled by industry leather waste fat biodiesel blend

The depletion of petroleum reserves and increasing environmental concerns prompted significant research into alternative fuels. This work, biodiesel, is extracted from the byproduct of industrial leather waste fat to generate beneficial energy.The main objective of this study is to enhance common rail direct injection (CRDI) diesel engine outcome characteristics by substituting industrial leather waste fat biodiesel (ILWFB) with the mixing of aluminium nitrate (Al (NO3)3) nanoparticles and graphene oxide nanoplates (GONPS) in the proportion of 50 ppm (parts per million) as catalysts to enhance ignition process. This research found that with the mixing of Al (NO3)3 nanoparticles and GONPS 50 ppm into the ILWFB blend, the in-cylinder pressure increased by 0.463% and 1.5%, and the heat release rate (HRR) improved by 4.19% and 12.04% than diesel and ILWFB blend at maximum load circumstances. Brake thermal efficiency (BTE) increased by 3.1% and 5.27%, and brake specific fuel consumption (BSFC) decreased by 3.57% and 7.14% in D50ILWFB50+Al (NO3)3 50 ppm blend and D50ILWFB50+GONPS 50 ppm blend related to diesel fuel. The carbon monoxide (CO), hydrocarbon (HC), and smoke emissions were reduced by 26.84%, 13.11%, and 5.75% in D50ILWFB50+Al (NO3)3 50 ppm blend and 38.94%, 21.31%, and 9.12% decreased in D50ILWFB50+GONPS 50 ppm blend than diesel fuel. Oxides of nitrogen (NOx) emissions marginally increased by 3.66%, 5.42%, and 8.94% in ILWFB blend, D50ILWFB50+Al (NO3)3, and D50ILWFB50+GONPSrelated to pure diesel at peak load conditions. This work concluded that the nano additives effectively enhanced BTE and decreased BSFC, CO, HC, and smoke emissions in diesel engine applications.

Investigations on the effects of injection parameters and EGR in a glow plug assisted methanol fueled Hot Surface Ignition (HSI) Engine

Methanol can be produced from renewable sources and is also clean burning. Hence it is an ideal alternative fuel for transportation applications. However, its low cetane number prevents its direct application in compression ignition (CI) engines. One of the promising but not widely explored methods is to use a hot surface for its ignition in CI engines at normal compression ratios. In this work a turbocharged automotive common rail diesel engine was modified to operate in the hot surface ignition (HSI) mode with methanol as the sole fuel with 3% by mass of lubricity and corrosion inhibiting additive. Initially, a single pulse injection (SPI) strategy was employed at different injection timings at a BMEP of 8 bar. Subsequently a double pulse injection (DPI) strategy was employed and the effects of gap between the injection pulses, injection timing and injection pulse width share among the two pulses were studied. The HSI mode of neat methanol performed with comparable brake thermal efficiency (BTE), reduced combustion rates and hence low NOx emission levels with respect to diesel operation when the DPI mode was employed with almost equal pulse width share. Engine performance was better at rail pressures of around 800 bar. Hot EGR of up to 8% was beneficial as it reduced the engine-out NOx without affecting the BTE. The engine was operated at different BMEPs in the range of 4–10 bar and compared with the baseline diesel operation. The BTE was similar to the baseline diesel engine at all loads. Engine-out NOx was lower than diesel operation by 23.6%–61.5% while near zero smoke levels and similar CO and THC emissions (after the DOC) were observed. Though slipped methanol and formaldehyde were the significant unregulated emissions, they were reduced to very low levels after the DOC.

Real-time estimation of fuel injection rate and injection volume in high-pressure common rail systems

The injection rate and injection volume are essential parameters for the combustion process, which greatly affect the engine efficiency and emission performance. However, at the current time the injection information cannot be obtained in real time during the actual operation of engine. This paper presents a novel real-time estimation method for the injection rate and injection volume based on the measurable rail pressure. A comprehensive dynamic model is derived by considering both the effect of fuel injection and supply process on the pressure fluctuation. Then a linear time-varying state space model is constructed by choosing three appropriate state variables. On this basis, considering the measurement noise and model uncertainty, a Kalman filter-based estimation method of the injection information is investigated. And the noise covariance matrix Q is optimally designed to adapt to a wide range of operating conditions. The proposed estimation method is validated on the different conditions, and the results show the injection rate estimation errors are within 4.5 %, the injection volume estimation errors are within 4 %. And on the situation with overlap of injection and supply process, the injection rate and injection volume estimation errors are all within 4.5 %.

Experimental investigations of CI engine performance using ternary blends of n-butanol/biodiesel/diesel and n-octanol/biodiesel/diesel

This study explored the ternary blends of biodiesel-diesel-n-butanol and biodiesel-diesel-n-octanol on common rail direct injec-tion (CRDI) diesel engines. The compositions of fuels, which varied from 0% to 100%, were altered by up to 5%. On the basis of their properties, these blends were chosen, with various concentrations of alcohol at 5% and 10%, 5% diesel, and the remainder being biodiesel. Two ternary fuel blends of waste cooking oil biodiesel (90–85%), diesel (5%), and butanol (5–10%), namely BD90D5B5 and BD85D5B10, and subsequently, another two ternary similar blends of waste cooking oil biodiesel (90–85%), diesel (5%), and octanol (5–10%), namely BD90D5O5 and BD85D5O10, were used to conduct the experiments. The experiments were done with varying injection pressure from 17° to 29° crank angle (CA) before top dead centre (bTDC). The optimum con-dition for the blends is achieved at 26°CA bTDC for 80% loading. So, the engine trials were conducted on 26°CA bTDC to attain the results. The BD90D5O10 blend achieved the lowest brake specific fuel consumption (BSFC) reading of 0.308 kg/kWh while operating at full load. The maximum brake thermal efficiency (BTE) was 31.46% for BD90D5B5. The maximum heat release rate (HRR) achieved with BD85D5O5 fuel blend was 58.54 J/°CA. The quantity of carbon monoxide that BD85D5B10 created was the lowest (25.86 g/kWh). BD85D5B10 had a minimal unburned hydrocarbon emission of 0.157 g/kWh while operating at full load. Oxides of nitrogen (NOx) were emitted in the maximum quantity by BD85D5O10, which was equal to 6.01 g/kWh. This study establishes the viability of blends of biodiesel and alcohol as an alternative for petro-diesel in the future to meet the growing global energy demand.

Investigation of the effect of injection rate shaping on combustion and emissions in heavy-duty diesel engine under steady and transient conditions

The fuel injection rate (ROI) is a crucial factor that affects the combustion and emissions of diesel engines. This study focuses on the injection pressure in a common rail system, which is divided into a high-pressure section and a low-pressure section. A control-oriented ROI shaping (ROIs) model is developed based on the switching strategy between high and low injection pressure. Three types of ROI were generated, namely ROIB (conventional ROI), boot-ROI (low followed by high injection pressure), and anti-boot-ROI (high followed by low injection pressure) respectively. The 1-D and 3-D numerical simulations are conducted to analyze the impact of the shaped ROI on combustion and emissions for steady condition and transient condition. In terms of overall results, boot-ROI shows significant advantage among the three types of ROI. For the steady condition, the boot-ROI was able to increase the IMEP (indicated mean effective pressure) (1.57 bar) at high load conditions with almost unchanged NOx emission. For low load conditions with delayed SOI (start of injection), the exhaust temperature is close to that of the ROIB with a reduction of 0.51 g/kW·h in NOx emissions. For transient condition, the boot-ROI also shows its advantage. It was found to improve the BSFC (brake specific fuel consumption) with almost unchanged NOx emission during load-down process. And in load-up process, the BSFC and soot emission also could be improved with slightly increase in NOx emission through advance of SOI when boot-ROI was adopted. The one-dimensional model using boot-ROI reduces fuel consumption by 2 g/kW·h in experiment with WHTC cycles, with slightly higher soot emission and similar NOx emission.

Optimization and impact of modified operating parameters of a diesel engine emissions characteristic utilizing waste fat biodiesel/di-tert-butyl peroxide blend

This study comprehensively investigated the transesterification process of converting waste pork fat oil into biodiesel as a fuel for the common rail direct injection (CRDI) diesel engine. In addition, Di-tert-butyl peroxide (DTBP) is used as an ignition enhancer to minimize exhaust gas emissions. The test fuels are diesel and diesel-waste pork fat biodiesel (WPFB)-DTBP blend (B20DTBP10 by volume), were used to analyze the engine outcome parameters with modified engines operating conditions like various compression ratios (CRs 16, 17.5, and 19) and injection pressures (IPs 400, 500 and 600 bar) at maximum load. The experiment results revealed that higher CRs and IPs, the heat release rate (HRR) and cylinder pressure increased. The brake thermal efficiency (BTE) is enhanced by increasing CRs and IPs but lowered than neat diesel. Smoke opacity decreased while increasing CRs and IPs. At CR 19 and IP 600 bar, smoke opacity decreased by 18.29%, related to baseline diesel. Increasing CRs and IPs lowered HC and CO emissions, but increasing IPs increased both emissions. HC and CO emissions were lowered in CR 19 and IP 500 bar by 21.73% and 28.49% more than neat diesel. The lower CRs and IPs, the oxides of nitrogen (NOx) emissions decreased, but further increasing CRs and IPs, the NOx emissions increased. Compared to baseline diesel, NOx emissions decreased in CR 16 and IP 400 bar by 15.49%. It was discovered that with increasing CRs and IPs, the emissions decreased with a minor rise in NOx emissions. Furthermore, the experimental results matched the predictions of an artificial neural network (ANN) model. The research concluded that the blend B20DTBP10 with modified engine operating conditions CRs and IPs suits diesel engine operation.

Comparative Analysis of Performance and Emission Characteristics of Biodiesels from Animal Fats and Vegetable Oils as Fuel for Common Rail Engines

Currently, solving global environmental problems is recognized as an important task for humanity. In particular, automobile exhaust gases, which are pointed out as the main cause of environmental pollution, are increasing environmental pollutants and pollution problems, and exhaust gas regulations are being strengthened around the world. In particular, when an engine is idling while a car is stopped and not running, a lot of fine dust and toxic gases are emitted into the atmosphere due to the unnecessary fuel consumption of the engine. These idling emissions are making the Earth’s environmental pollution more serious and depleting limited oil resources. Biodiesel, which can replace diesel fuel, generally has similar physical properties to diesel fuel, so it is receiving a lot of attention as an eco-friendly alternative fuel. Biodiesel can be extracted from various substances of vegetable or animal origin and can also be extracted from waste resources discarded in nature. In this study, we used biodiesel blended fuel (B20) in a CRDI diesel engine to study the characteristics of gases emitted during combustion in the engine’s idling state. There were a total of four types of biodiesels used in the experiment. New Soybean Oil and New Lard Oil extracted from new resources and Waste Soybean Fried Oil and Waste Barbecue Lard Oil extracted from waste resources were used, and the gaseous substances emitted during combustion with pure diesel fuel and with the biodiesels were compared and analyzed. It was confirmed that all four B20 biodiesels had a reduction effect on PM, CO, and HC emissions, excluding NOx emissions, compared to pure diesel in terms of the emissions generated during combustion under no-load idling conditions. In particular, New Soybean Oil had the highest PM reduction rate of 20.3% compared to pure diesel, and Waste Soybean Fried Oil had the highest CO and HC reduction rates of 36.6% and 19.3%, respectively. However, NOx was confirmed to be highest in New Soybean Oil, and Waste Barbecue Lard Oil was the highest in fuel consumption.

Simulation of a Novel Integrated Multi-Stack Fuel Cell System Based on a Double-Layer Multi-Objective Optimal Allocation Approach

A multi-stack fuel cell system (MFCS) is a promising solution for high-power PEM fuel cell applications. This paper proposes an optimized stack allocation approach for power allocation, considering economy and dynamics to establish integrated subsystems with added functional components. The results show that an MFCS with target powers of 20 kW, 70 kW, and 120 kW satisfies lifetime and efficiency factors. The common rail buffer at the air supply subsystem inlet stabilizes pressure, buffers, and diverts. By adjusting the volume of the common rail buffer, it is possible to reduce the maximum instantaneous power and consumption of the air compressor. The integrated hydrogen supply subsystem improves hydrogen utilization and reduces parasitic power consumption. However, the integrated thermal subsystem does not have the advantages of integrated gas supply subsystems, and its thermal management performance is worse than that of a distributed thermal subsystem. This MFCS provides a solution for high-power non-average distribution PEM fuel cell systems.

Integrated optimization of common rail direct injection diesel engine input parameters with linseed biodiesel: A hybrid approach using grey relational analysis and genetic algorithm techniques

In the pursuit of improved productivity and efficiency, the search for alternative fuels that reduce dependence on fossil fuels is of utmost importance. This research study aims to investigate the influence of process parameters, namely blend percentage, fuel injection pressure, exhaust gas recirculation (EGR) rate, and engine load, on various engine performance parameters such as torque, brake thermal efficiency (BTE), brake mean effective pressure (BMEP), hydrocarbon emissions (HC), and mechanical efficiency. The experiments are conducted following the Taguchi orthogonal array (L25) design of experiments. Additionally, grey relational analysis, a multi-objective optimization technique, is applied to identify the optimal levels of the process variables that optimize all the response parameters. The optimal values obtained through grey relational analysis are determined as 0% blend, 600 bar fuel injection pressure, 12% EGR rate, and 12 kg engine load. Moreover, the Genetic Algorithm-based Multi-Objective Genetic Algorithm (MOGA) is employed for multi-objective optimization of the engine input variables, yielding optimal levels of 19.45% blend, 594.35 bar fuel injection pressure, 14.12% EGR rate, and 12 kg engine load. Furthermore, multivariable regression models are developed to predict the response variables within the experimental domain. These models are validated through a confirmation test. The findings of this study provide insights into the optimization of process variables for enhanced engine performance, with the developed models serving as valuable tools for future predictions and optimization.

Effects of Pre-Injection and Antioxidants in a Diesel Engine Fuelled with Methyl Esters of Waste Cooking Oil Biodiesel

Diesel engines are significant contributors to air pollution, particularly through emissions of nitrogen oxides (NOx), smoke, and carbon monoxide (CO). Finding sustainable fuel alternatives and additives to reduce emissions without compromising engine performance is imperative for environmental and public health concerns. This study investigates the impact of adding tert-butylhydroquinone (TBHQ) antioxidants to blends containing 20% Methyl Esters of Waste Cooking Oil (20MEOWCO) and 80% diesel fuel in Modified Common Rail Diesel (MCRD) engines. The experiment involves adjusting the pilot fuel injection timing to 36°CA bTDC (before Top Dead Centre) and the main injection timing to 15°CA bTDC, with a Nozzle Opening Pressure (NOP) of 500 bar. Biodiesel is produced from used cooking oil using standard procedures and then mixed with diesel fuel. Various concentrations of TBHQ are added to the 20MEOWCO fuel blend for the experiment. The findings indicate that introducing TBHQ in concentrations of 250 ppm and 500 ppm to the 20MEOWCO fuel blend results in a notable reduction of Oxides of Nitrogen (NOx) emission by 13% in MCRD engines. However, this reduction in emissions comes at the expense of increased specific fuel consumption, which is observed to rise by 2.1%. Furthermore, the study highlights a rise in smoke and carbon monoxide (CO) emissions by approximately 7–10% and 5-8%, respectively, under the experimental conditions. The results of this study suggest that the addition of TBHQ to 20MEOWCO blends holds promise for mitigating NOx emissions in MCRD engines.

Effects of biodiesel injector configuration and its injection timing on performance, combustion and emissions characteristics of liquid ammonia dual direct injection engine

Ammonia is a promising carbon-neutral fuel that can be stored and transported in liquid form, offering a viable alternative to diesel fuel. In addition, it can be used directly in diesel engine in its liquid form in dual fuel mode. Hence, a single-cylinder diesel engine was modified to implement two common rail (CR) injection systems, allowing the direct injection of liquid ammonia with biodiesel. As biodiesel was used for a pilot fuel with lower injected mass, this study aims to investigate the influence of the number of nozzles in the biodiesel injector on the performance, combustion, and emissions characteristics of the liquid ammonia-biodiesel dual direct injection engine. Therefore, the number of holes in the CR injector was closed in various configurations to improve injection parameters. Furthermore, various biodiesel start of injection (SOI) timings were tested, ranging from −24 to −14 CAD, while the SOI of ammonia was kept at −10 CAD with an ammonia mass ratio of 67.2%. The results showed that welding three nozzles from the original six-nozzle injector resulted in a remarkable 29.2% reduction in NH3 and CO emissions. Furthermore, the highest indicated thermal efficiency of 39.7% was obtained for the injector with 3b nozzles. Additionally, late injection of both fuels led to an increase in particulate matter emissions, from 10.5 to 15.2 mg/m3, due to the formation of fuel-rich zones at high temperatures. However, it reduced NOx and CO emissions by 1.4 and 4.4 g/kWh, respectively, compared to the early SOI of biodiesel. Moreover, the lowest N2O emission was measured at 115.0 ppm in the earliest SOI of biodiesel at −24 CAD.

Simulation study on the cavitation distribution in the ball valve of a common rail injector

A transient-state numerical simulation is conducted to investigate the cavitation flow in the ball valve of a common rail (CR) injector. The computational fluid dynamics (CFD) software, employing the RANS turbulence model, is employed for this purpose. The study aims to analyze the characteristics and underlying causes of the uneven distribution of cavitation in the ball valve. The results reveal a significant occurrence of cavitation, exhibiting an uneven distribution along the walls of both the ball and the valve seat. Notably, the initiation position of the intense cavitation region on the wall of the ball is observed to lag behind that on the wall of the valve seat. The intense cavitation region on the wall of the ball is found to reside behind the sealing surface of the ball valve. The intense cavitation region on the wall of the ball is located behind the sealing surface of the ball valve. This region experiences flow separation caused by main flow detour, resulting in the formation of vortices that entrapped the cavitation cloud, thus fostering the development of intense cavitation. Conversely, the intense cavitation region on the wall of the valve seat originates from the entrance of the ball valve. This can be attributed to the sudden change in geometry at the entrance, leading to a significant pressure drop and inducing cavitation based on geometric factors. Furthermore, the stagnation effect caused by the ball exacerbates the discrepancy in the distribution of the intense cavitation region between the ball and the valve seat.

Zero-Dimensional Modeling of the Rate of Injection with a Diesel Common Rail System Using Single-Hole Nozzles with Neat Low-Carbon Fuels

This paper presents a fuel injection rate predictive model based on zero-dimensional correlations from experimental results. This model estimates the fuel injection rate behavior with varying parameters such as fuel injection pressure-injector energizing, the injection nozzle geometrical characteristics, and fuel viscosity. The model approach was carried out with diesel fuel. Then, the model was applied to the use of two alternative low-carbon fuels without diesel. An experimental methodology was used under controlled conditions, employing an injection rate indicator to measure the injection parameters in real time. The setup was carried out on a pump test bench using a common rail injection system. The results show that the model can be adapted to different injection conditions and fuels.

Wear Reduction on the Roller–Shoe Mechanism at High Operation Loads

The roller–shoe mechanism is a classic mechanical assembly with an essential role in motion transmission. Common rail high-pressure pumps are an example of a complex assembly that uses such a mechanism to transform the rotation motion into a translation one. The rolling element of the mechanism is represented by a cylindrical roller. Although it can carry heavy loads due to its design, a proper surface profile could significantly increase the life of the entire mechanism. A better solution can be achieved using a logarithmic profile. The shoe is the second base element of the mechanism. It is a part with an inner cylindrical surface and it is separated from the roller by a thin lubricant film. Considering this, increasing the hardness of the roller–shoe contact surface can be obtained using a suitable coating. The positive results of this coating are highlighted using endurance tests to which high-pressure pumps are subjected. Therefore, the roller profile and the shoe coating represent two directions for improving the contact between the mechanism transmission elements, in terms of wear reduction. The purpose of this paper is to identify a suitable roller profile and to highlight its impact on the shoe coating.