Direct Injection Compression Ignition Engine Research Articles

A full-parameter computational optimization of both injection parameters and injector layouts for a methanol/diesel dual-fuel direct injection compression ignition engine

Both the injection parameters and injector layouts of a methanol/diesel dual-fuel direct injection compression ignition engine operated at low loads were optimized using the genetic algorithm to achieve high fuel efficiency and low emissions simultaneously. The important parameters were identified according to the sensitivity analysis, including the in-cylinder initial temperature at intake valve closing (TIVC), methanol fraction, injection timings, and injector locations. The vaporization cooling effect of the direct-injected methanol can be compensated by elevating TIVC, so the maximum methanol fraction depends on the TIVC level. Diesel should be injected before methanol to create a high-reactivity and high-temperature region to trigger ignition efficiently. Spray included angles of diesel and methanol affect the combustion process by controlling the distributions and Overlap Degree of two fuels, and a relatively high Overlap Degree is beneficial to both combustion efficiency and fuel efficiency by targeting the spray plumes of two fuels toward the piston lip. When the methanol injector is off-center installed, the increased Overlap Degree of two fuels is helpful to improve fuel efficiency with a penalty of higher nitrogen oxides (NOx) emissions. Overall, both injectors are suggested to be centrally mounted, and a small off-center installation is allowed for two injectors without deteriorating engine performance, when the partially premixed combustion is performed with advanced injection timings.

Analysis of Thermomechanical Stress of High-Temperature Ignition Surface Caused by Drop–Wall Interaction at Engine Conditions

Abstract Drop–wall interaction is a complex phenomenon encountered in diverse industrial applications. An important example is fuel droplets impinging on a high-temperature ignition plug in a direct-injection compression-ignition engine. The ignition plug, comprised of heat-resistant materials, will experience thermal shock due to abrupt temperature changes. The ensuing temperature fluctuation in the solid wall induces thermal stress, and if this stress surpasses the material's strength in that mode, failure can occur. Therefore, it is imperative to analyze the temperature dynamics on the high-temperature surface to enhance material durability. This study focuses on drop–wall interactions in the engine environment. Utilizing the Smoothed Particle Hydrodynamics (SPH) method, this research simulates fuel droplet impingement on an ignition plug with various materials to characterize heat transfer, thermal penetration, and temperature distributions in the heated wall. The investigation also delves into the behavior of ceramic material, specifically silicon nitride, assessing its thermomechanical stress and durability based on the stress–number of cycles (S-N) curve. Thermal stress is computed by considering temperature gradients and material properties, while mechanical stress is evaluated based on the bending momentum and momentum flux induced by the spray. A parametric study explores diverse materials such as tungsten carbide, iron, stainless steel, carbon steel, and aluminum. Results indicate that thermal stress outweighs bending and spray-induced stress. Moreover, the analysis reveals that silicon nitride exhibits the lowest thermal stress distribution and superior durability, potentially capable of operating for infinite cycles under engine-relevant conditions.

Compression Ignition Internal Combustion Engine’s Energy Parameter Research Using Variable (HVO) Biodiesel and Biobutanol Fuel Blends

This study investigates the impact of different biofuels, such as pure hydrogenated vegetable oil, hydrogenated vegetable oil, and biobutanol, as well as their blends, on the non-energetic operational characteristics of a compression ignition internal combustion engine. The research investigations were conducted using a turbocharged direct injection compression ignition engine that was put within a Skoda Octavia 1.9 TDI automobile. Throughout the investigation, the primary emphasis was placed on analyzing energy characteristics such as power, brake-specific fuel consumption (BSFC), brake thermal efficiency (BTE), and other related factors. The analysis involved the utilization of multiple combinations of bio-based fuels, namely four mixes of HVO with biobutanol (HVO100, HVOB5, HVOB10, and HVOB20), which were subsequently compared to fossil diesel (D100). The findings of the study indicate that the utilization of HVO100 fuel results in notable reductions in power output and mass fraction when compared to D100 gasoline. HVO100 fuel demonstrates superior performance to D100 gasoline, exhibiting a range of 1.7% to 28% improvement in brake-specific fuel consumption. Additionally, at an engine speed of 4500 rpm, the use of HVO100 fuel leads to a decrease in brake thermal efficiency of 4.4%.

Enhancement of Efficiency and Mitigation of Pollutan Emissions in a Compression Ignition Engine by the Utilization of Rice Bran Oil as Green Fuel

The current investigation involved the implementation of a research experiment aimed at assessing the operational and emission attributes of a compression ignition direct injection engine comprising a single cylinder. The engine was fuelled with rice bran oil (RBO), and its performance was analysed under different engine loads. The performance metrics that were analysed included the brake specific fuel consumption BSFC), brake thermal efficiency (BTE), exhaust gas temperature (EGT), and cylinder pressure. The exhaust emission parameters that were investigated include carbon monoxide (CO), carbon dioxide (CO2), hydrocarbons (HC), and oxide of nitrogen (NOX). The study compares the results obtained from an experimental investigation involving different variants of rice bran oil (RBO50, RBO75, RBO100) with those obtained from a diesel engine (RBO00). The lowest BSFC obtained for RBO100 is around 0.29 kg/kWh at maximum load conditions (75 %), while the highest obtained for RBO00 is 0.33 kg/kWh. For all operations of diesel and RBO blends, it was discovered experimentally that the BSFC increases until 25 % of engine load and then starts to decline as the engine load is raised. At normal engine load circumstances, RBO75 has the highest thermal efficiency, while RBO00 has the lowest. The high EGT reading of RBO50 blends was due to the high calorific value (CV) of the fuel blends, which produced more heat per unit mass than RBO75 and RBO100. RBO75 achieved the highest cylinder pressure under both half and full load scenarios. RBO00 (pure diesel) achieved the lowest cylinder pressure under both half and full load scenarios. RBO outscored diesel in terms of efficiency of engine. The exhaust emission characteristics that were assessed included NOX, CO2, HC, and CO. The experimental outcomes of the study using rice bran oil-based fuels, specifically RBO50, RBO75, and RBO100, are being contrasted with those of diesel fuel (RBO00). The findings indicate that emissions of CO, CO2, HC, and NOX are lower when using RBO75 and RBO100 compared to diesel fuel. Furthermore, an analysis was conducted to determine the HC emissions of both RBO75 and RBO100 fuels at two distinct engine speeds, specifically 3500 rpm and 2000 rpm. The HC emission level for RBO75 was observed to be at its peak of 211 ppm when the engine speed reached 3500 rpm. The RBO50 fuel exhibits lower levels of CO emissions, measuring at 1.2% (3500 rpm) and 0.32% (2000 rpm). Similarly, CO2 emissions are also reduced with RBO50, measuring at 8.3% (3500 rpm) and 6.9% (2000 rpm). These exhaust emission reductions are observed when comparing RBO50 to diesel (RBO00) and other fuel mixtures, under a 75% load condition. Elevated levels of NOX emissions were detected in diesel fuel (RBO00) at concentrations of 499 ppm (3500 rpm) and 599 ppm (2000 rpm). In comparison to other fuels such as RBO50, RBO75, and RBO100, these higher NOX emissions were noted. In summary, the emission properties of RBO were shown to be superior to those of diesel fuel. The optimal blend for emissions reduction, including CO2, CO, NOX, and HC, was determined to be RBO50.

Comparison of Engine Performance and Emissions for W20 and P20 Methyl Ester Blends as Fuel

Demand for energy in transportation, industrial and other energy sectors has led to the huge consumption of fossil fuels. This has directly affected on climatic issues, global warming as well as financial status of a country. In order to reduce these problems biofuels have been used in the engines. The present work reports the performance and emission studies conducted on an engine for W20 (waste cooking oil methyl ester 20% + diesel 80%) blend and P20 (pongamia methyl ester 20% + diesel 80%) blends on volume basis tested on a single cylinder 4-stroke water cooled compression ignition direct injection engine. At 2.2kW engine loading Brake Thermal Efficiency (BTE) for W20 and P20 blends are 2.11% and 5.92% lesser than that of diesel fuel. Brake Specific Fuel Consumption (BSFC) for W20 and P20 blends are 2.386% and 0.198% higher than that of diesel respectively. Exhaust Gas Temperature (EGT) for W20 and P20 blends are 6.89% and 3.44% greater than that of diesel respectively. Carbon Monoxide (CO) emissions for W20 and P20 blends are 0.046%, 0.04% lower, Carbon Dioxide (CO2) emissions for W20 and P20 blends are 0.33% and 0.18% higher than that of diesel respectively. Hydro Carbon (HC) emissions for W20 blend is 56% higher and P20 blend is 12% lower when compared with diesel. Oxides of Nitrogen (NOx) for W20 and P20 blends are 18.87% and 1.72% larger than that of diesel. Therefore, P20 blend fuel is good when compared to W20 blend fuel.

Numerical investigation for enhancing HCCI combustion characteristics in DI-CI engine fueled with butanol/diesel blends

The fast depletion of fossil fuels and the hazardous emissions associated with the use of fossil fuels in IC engines is driving the research in the area of renewable fuels. Homogeneous charge combustion ignition (HCCI) is a new mode of engine combustion technology, used for reducing the emissions without compromising the engine performance. The combination of HCCI and alcohol/diesel blends has the potential to simultaneously address the twin problems of depletion of fossil fuels and engine emissions. Butanol is an attractive biofuel, which is produced from agriculture wastes such as sugar cane bagasses and corn stalk etc. This paper presents numerical and modeling analysis on the emission and performance characteristics of a direct injection- compression ignition (DI-CI) engine operated with butanol/diesel blends. Numerical analysis was carried out using CONVERGE CFD software. Response surface methodology (RSM) was used in developing the response models for three output parameters, viz., nitrogen oxides (NOx), soot emissions and indicated specific fuel consumption (ISFC), in terms of the four input parameters, viz., compression ratio (CR), start of injection (SOI), fuel injection pressure (FIP) and exhaust gas recirculation (EGR). Numerical experiments were conducted by varying these four input parameters, i.e., CR from 14 to 19, FIP from 200 to 280 bar, EGR from 0% to 30% and SOI from 17° to 29° CA bTDC, and with four butanol/diesel blends (0, 20%, 30% and 40% of butanol-by volume, designated as Bu00, Bu20, Bu30 and Bu40). The optimum combination of the input parameters for the four test fuels were found with the objective of minimizing the three output parameters (i.e., ISFC, soot and NOx) using desirability approach. The homogeneity of the air-fuel mixture was estimated using equivalence ratio distribution index, i.e., Target fuel distribution index (TFDI). From the numerical analysis, it was found that the TFDI improved for the optimized case by 20.5%, 21.5%, 24.4% and 27.2% for Bu00, Bu20, Bu30 and Bu40 respectively as compared to their respective baseline configuration.

Efficacy of performance and mitigate pollution of CI engine: Delonix regia biodiesel with n‐butanol and exhaust gas recirculation

AbstractThe primary aim of this research study was to examine the effectiveness and environmental consequences of using Delonix regia biodiesel (DRB) in combination with butanol (BUT), exhaust gas recirculation (EGR), and diesel fuel (D) on a direct injection compression ignition engine operating at a constant speed. This study involved the formulation of five distinct biodiesel blends, namely DRB10% + D90%, DRB20% + D80%, DRB10% + BUT10% + D80%, DRB10% + BUT20% + D70%, and DRB20% + D80% + EGR10%. The inclusion of n‐butanol in a biodiesel blend serves to tackle the problem of inadequate combustion in fuel blends by alleviating the oxygen deficiency that occurs during the combustion process. The findings of the study revealed that the combination of DRB at 10%, BUT at 20%, and D at 70% produced in a significant reduction in specific fuel consumption (SFC) by 11.19% and brake thermal efficiency by 2.62%. Additionally, this combination led to a decrease in exhaust emissions of CO and Smoke, with the exception of HC and NOx, when compared to the use of diesel fuel. The control of HC and NOx emissions can be achieved through the implementation of an exhaust gas recirculation system. The results of this investigation suggest that Delonix regia biodiesel, in combination with a 20% concentration of n‐butanol, has potential as a viable alternative fuel choice that may be utilized without necessitating any engine modifications.

Performance and Emission Analysis of Biodiesel Blends in a Low Heat Rejection Engine with an Antioxidant Additive: An Experimental Study.

The rapid depletion of crude oil and environmental degradation necessitate the search for alternative fuel sources for internal combustion engines. Biodiesel is a promising alternative fuel for compression ignition (CI) engines due to its heat content and combustion properties. Biodiesel blends are used in various vehicles and equipment, such as cars, trucks, buses, off-road vehicles, and oil furnaces. Biodiesel can reduce emissions from CI engines by up to 75% and improve engine durability due to its high lubricity. However, biodiesel has some drawbacks, including a performance reduction and increased nitrogen oxide emissions. Therefore, this study aims to investigate using environmentally available biodiesel in a low-heat rejection engine and an antioxidant additive to enhance the performance and reduce nitrogen oxide emissions. India currently has several biodiesel sources, including mango seed oil, mahua oil, and pongamia oil, which can be effectively utilized in CI engines by adding l-ascorbic acid. The experimental work involves a single-cylinder 4-stroke water-cooled direct injection CI engine with a power output of 5.2 kW. The engine's cylinder head, piston head, and valves are coated with lanthanum oxide using the plasma spray coating technique, with a thickness of 0.5 mm. The coated and uncoated engines are tested with different proportions of mahua oil, mango seed oil, and pongamia oil. The results show that the engine's performance is significantly improved compared to the baseline engine at all loads. Additionally, these biodiesels exhibit a notable reduction in nitrogen oxide emissions when combined with l-ascorbic acid.

Performance analysis of a diesel engine using margosa oil ethyl ester-based biodiesel with diethyl ether as an oxygenated additive

In this study, the effect of Margosa oil ethyl ester (MOEE) with oxygenated additive Diethyl ether (DEE) on the thermal performance, combustion, and emission characteristics of a direct-injection compression ignition engine (CIE) was examined. Experiments were performed under various engine loadings at a constant speed of 1500 rpm. Two-step transesterification process was followed for producing MOEE-based biodiesel from Margosa oil owing to its high free fatty acid content. Further, four different blends of MOEE and Diesel with fixed DEE concentration (5% by vol.) were fuelled in a CIE and compared its performance with Diesel. Results showed that the increase in MOEE proportion in the blends decremented the mean brake thermal efficiency and the maximum reduction was about 14.3% for MOEE20 as compared to diesel. Moreover, there was a decline in In-cylinder pressure and net heat release rate when MOEE20 fuelled in a CIE by up to 8.1% and 8.7% respectively. Emission results found that the MOEE blends emitted more oxides of nitrogen and carbon dioxide by up to 18.8% and 14.7% respectively with a major decrement in emissions of hydrocarbon by up to 41.2%. Overall, it is concluded that the fueling of MOEE20 could be the plausible option for swapping the diesel usage in CIE with an excellent reduction in emission despite a marginal drop in performance.

Effects of hydrogen and EGR on energy efficiency improvement with ultra low emissions in a common rail direct injection compression ignition engine fueled with dimethyl ether (DME) under HCCI mode

This study deals with enhancing the energy efficiency with ultra-low emissions and extending the operating range (maximum load limit) of dimethyl ether (DME) fueled homogeneous charge compression ignition (HCCI) engine using hydrogen and exhaust gas recirculation (EGR). In the neat DME mode, the possible maximum load limit with controlled auto-ignition (CAI) was found as 24% (BMEP of 1.67 bar). Beyond 24% load, the knocking was observed with an advanced combustion phase, and shortened combustion duration resulted in uncontrolled auto-ignition (UAI) combustion. The addition of EGR extended the maximum load limit to 52% (BMEP of 3.62 bar) (60% EGR). Near-zero levels of NOx, zero smoke, and marginal CO and HC emissions reduction were observed with the optimized EGR rate (35%). The hydrogen fuel addition along with DME at an optimized EGR rate resulted in combustion phase retardation with the elimination of the low-temperature reaction (LTR) region. The energy efficiency (EE) and indicated thermal efficiency (ITE) increased along with zero smoke emission, ultra-low NOx, CO, and HC, and lower CO2 emissions till 12% of hydrogen energy share (HES). Thus, the combined strategy of EGR and hydrogen could effectively extend the operating range with ultra-low emissions levels.

Modelling of multiple biodiesel-emitted nitrogen oxides using ANN approach

This research paper focuses on modelling of nitrogen oxides emitted by diesel engine for multiple biodiesel blends. A lot of research work has observed that the properties of biodiesel blends affect the nitrogen oxide emissions. To this aim, total of fifteen blends of multiple biodiesels are prepared on vol. % by using four non-edible category biodiesels. The suitability and quality of the biodiesel and diesel blends are tested through a characterization and found within the permissible limits of ASTM. The experimentation has been carried out on a direct injection compression ignition (DICI) engine with constant speed and varying loading condition from no load to full load in a step of 25%. During the experimentation, the NOx emissions are measured using a Netel MGA-2 exhaust gas analyzer. The study revealed that several properties such as viscosity, density, mean gas temperature, etc. affect NOx emission. In addition, NOx emission increases with an increase in BPs. The artificial neural network (ANN) is performed by considering physicochemical and thermal properties as a function. The ANN predicts the estimated NOx with an accuracy of 0.99.

Hydrogen influence on kapok methyl ester blended with DEE as an alternate fuel in CI engine

Kapok oil methyl ester (KOME) is used as a pilot fuel, while hydrogen and diethyl ether (DEE) are used as secondary fuels to improve the performance, emissions and combustion of a direct injection compression ignition engine. With a compression ignition engine, a slight modification to the system enables hydrogen gas through the intake manifold. A flow metre limits the quantity of energy the hydrogen may produce off, and two flame arresters prevent backfires in the fuel line. At full load and maximum hydrogen energy sharing, KOME + 20%DEE obtained a brake thermal efficiency of 30.31%, which is 14% higher than without hydrogen enrichment and about 8% higher than diesel's value (0% hydrogen energy share). The main problem with previous research is that hydrogen with a high heating value makes greater amounts of nitric oxide. Diethyl ether, on the other hand, has fixed this major problem, and the absence of carbon in hydrogen fuel lowers CO, HC and smoke emissions.

Effect of green fuel and green lubricant with metallic nanoparticles on emissions of HC, CO, NOx, and smoke for a compression ignition engine

The United Nations Sustainable Development Goals (SDGs) are imperative from the point of view of protecting the environment by employing sustainable options. Considerable research has been carried out in the transportation sector to meet this objective. Here, the influence is assessed of epoxidised gingelly oil methyl ester biolubricant with alumina (Al2O3) nanoparticles on the performance and emissions of a single cylinder 0.66-L capacity direct injection compression ignition engine driven by gingelly B20 biodiesel. Engine tests are carried out with gingelly B20 biodiesel as a fuel, and gingelly methyl ester (B100), epoxidised gingelly methyl ester (B100E), and epoxidised gingelly methyl ester (B100E) mixed with 0.5%, 1.0%, and 1.5% w/w alumina (Al2O3) nanoparticles as the lubricant combinations. The results are compared with baseline B20 biodiesel fuel-mineral lubricant operation. The findings indicate that brake thermal efficiency increases by 8.64% for epoxidised gingelly methyl ester (B100E) with 1.0% w/w alumina (Al2O3) nanoparticle biolubricant in comparison to baseline operation. Considerable reductions in emissions are detected; specifically, reductions of 52.4%, 22.0%, 20.0%, and 34.9%, respectively, are observed for CO, NOx, and HC concentrations and smoke opacity for the abovementioned combination as compared to baseline operation. The present work suggests that further research is merited on green fuel-green lubricant combinations. The findings of this study address the United Nations Sustainable Development Goals (SDGs) 7 and 13.

Sustainable nano-added biofuel production from borassus flabellifer oil for conventional internal combustion engines

The source of biodiesel production is significant as the demand for diesel is very high. Sustainable fuel development is the prime aim of meeting the demand. Drought-tolerant trees are widely available and can cultivate more to increase the feedstock capacity. Hence, this experimental research investigates the potential for deriving an alternative fuel from borassus flabellifer. Accordingly, this research employed biodiesel production from borassus flabellifer oil through the transesterification technique with methanol at 65 °C of temperature for 3 h with 300 rpm of magnetic stirrer speed. The blends by volume of 20% biodiesel of borassus flabellifer (20BOPP) and 80% of diesel (80D) were used to create the Biodiesel of borassus flabellifer blend (20BOPP+80D). Then it is enhanced by mixing 100 ppm of aluminium oxide nanoparticles (AONP) in that fuel to produce the nano-fuel of 20BOPP+80D + AONP. The base fuel (20BOPP) is enhanced by preparing a new blend of 20% ethanol (20 E) and 60% diesel added with 20BOPP to produce 20BOPP+20E+60D and then the new class of fuel enhanced by AONP to produce 20BOPP+20E+60D + AONP. The nano-fuel was prepared with the help of an ultrasonicator. The prepared blends and conventional diesel fuel were tested at varying engine loads, and the results revealed that the enhanced nonfuel of 20BOPP+20E+60D + AONP produced equivalent brake thermal efficiency (BTE) of 31.94% like diesel fuel, reducing the emission nitrogen oxides (NOx) by 29.2% and emission of Carbon Monoxide (CO) emission by 11.4% to pure diesel fuel. The enhanced nano-fuel of 20BOPP+20E+60D + AONP reduced smoke opacity by 35.3% more than pure diesel. Hence the mixing of both alcohol and nanoparticles in the biodiesel blend produces better results at maximum load conditions than their performance mixing individually in the biodiesel blend due to the alcohol's higher volatility and nanoparticles catalytic reaction during combustion in the Direct-Injection Compression Ignition (DICI) engine due to the alcohol's higher volatility and nanoparticles catalytic reaction during combustion stage.

Simulations of ammonia spray evaporation, cooling, mixture formation and combustion in a direct injection compression ignition engine

This study investigates the novel approach of direct liquid ammonia injection into the combustion chamber of a compression ignition engine. Unlike traditional gaseous ammonia port injection, this method shows promise in reducing ammonia slip and emissions. To simulate and analyze the behavior of the liquid ammonia spray, we employed numerical models based on existing literature on flashing and non-flashing spray simulations, as well as recent experimental studies on ammonia spray characteristics using a gasoline direct injection (GDI) injector. Our approach utilized a Lagrangian discrete phase modelling technique to perform a series of three-dimensional computational fluid dynamics (CFD) simulations. The primary objectives of this research were to evaluate the evaporation process of ammonia and its cooling effect, as well as to gain insights into mixture formation within the engine cylinder under different operating conditions. The simulations encompassed the entire engine cycle, considering a multi-hole GDI ammonia spray in conjunction with pilot n-heptane, a diesel surrogate, in equal proportions on an energy basis. Three distinct injection timings for ammonia were examined, leading to varying thermodynamic conditions within the combustion chamber during each spray formation. Consequently, different modelling parameters and initial conditions were necessary to accurately replicate the spray behavior. To address this, we proposed a systematic procedure for assigning pre-defined spray angles. The non-reacting, evaporating spray simulations yielded valuable insights into the mixture formation process, which guided our analysis. Finally, reacting conditions were considered to evaluate engine performance and resulting exhaust gas emissions. This study provides a comprehensive overview of critical aspects related to direct ammonia injection in internal combustion engine (ICE) systems. Moreover, it uncovers performance trends that can serve as a foundation for future investigations in this field.

Numerical study of heat transfer of hydrogen combustion in noble gases atmosphere in compression ignition engine

The high energy content of hydrogen and zero carbon emission from hydrogen combustion is very important for compression ignition engine development. Hydrogen requires a very high auto-ignition temperature, which encourages replacing nitrogen with noble gases with higher specific heat ratio during compression process. In noble gases-hydrogen combustion, higher combustion temperature potentially leading to a higher heat loss. This paper aims to investigate the effect of hydrogen combustion in various noble gases on heat distribution and heat transfer on the cylinder wall. Converge CFD software was used to simulate a Yanmar NF19SK direct injection compression ignition engine. The local heat flux was measured at different locations of cylinder wall and piston head. The heat transfer of hydrogen combustion in various noble gases at different intake temperatures was studied using the numerical approach. As a result, hydrogen combustion in light noble gases such as helium produces faster combustion progress and higher heat temperature. The hydrogen combustion that experienced detonation, which happened in neon at 340 K and argon at 380 K, recorded a very high local heat flux at the cylinder head and piston due to the rapid combustion, which should be avoided in the engine operation. At a higher intake temperature, the rate of heat transfer on the cylinder wall is increased. In conclusion, helium was found as the best working gas for controlling combustion and heat transfer. Overall, the heat transfer data gained in this paper can be used to construct the future engine hydrogen in noble gases.

Analysis of CRDI diesel engine characteristics operated on dual fuel mode fueled with biodiesel-hydrogen enriched producer gas under the single and multi-injection scheme

The present work aims to investigate the consequences of pilot fuel (PF) multiple injections and hydrogen manifold injection (HMI) on the combustion and tailpipe gas characteristics of a common rail direct injection (CRDI) compression ignition (CI) engine operated on dual fuel (DF) mode. The CI engine can perform on a wide variety of fuels and under high pilot fuel (PF) pressure. Pilot fuel injection (PFI) is achieved at TDC, 5, 10, and 15ºCA before the top dead center (bTDC), and divided injection consists of injecting fuel in three different magnitudes on a time basis and PF is injected into the engine cylinder at a pressure of 600 bar. In this work, the hydrogen flow rate (HFR) was fixed at 8 lpm constant and producer gas was inducted without any restriction. The investigational engine setup has the ability to deliver a PF and hydrogen (H2) precisely in all operating circumstances using a separate electronic control unit (ECU). Results showed that diesel-hydrogen enriched producer gas (HPG) operation at maximum operating conditions provided amplified thermal efficiency by 4.01% with reduced emissions, except NOx levels, compared to biodiesel-HPG operation. Further, DiSOME with the multi-injection strategy of 60 + 20+20 and 50 + 25+25, lowered thermal efficiency by 4.8% and 9.12%, respectively compared to identical fuel combinations under a single injection scheme. However, reductions in NOx levels, cylinder pressure, and HRR were observed with a multi-injection scheme. It is concluded that multi-injection results in lower BTE, changes carbon-based emissions marginally, and decreases cylinder pressure and heat release rate than the traditional fuel injection method.

Parametric evaluation of ducted fuel injection in an optically accessible mixing-controlled compression-ignition engine with two- and four-duct assemblies

Ducted fuel injection (DFI) is a strategy to improve fuel/charge-gas mixing in direct-injection compression-ignition engines. DFI involves injecting fuel along the axis of a small tube in the combustion chamber, which promotes the formation of locally leaner mixtures in the autoignition zone relative to conventional diesel combustion. Previous work has demonstrated that DFI is effective at curtailing engine-out soot emissions across a wide range of operating conditions. This study extends previous investigations, presenting engine-out emissions and efficiency trends between ducted two-orifice and ducted four-orifice injector tip configurations. For each configuration, parameters investigated include injection pressure, injection duration, intake manifold pressure, intake manifold temperature, start of combustion timing, and intake-oxygen mole fraction. For both configurations and across all parameters, DFI reduced engine-out soot emissions compared to conventional diesel combustion, with little effect on other emissions and engine efficiency. Emissions trends for both configurations were qualitatively the same across the parameters investigated. The four-duct configuration had higher thermal efficiency and indicated-specific engine-out nitrogen oxide emissions but lower indicated-specific engine-out hydrocarbon and carbon monoxide emissions than the two-duct assembly. Both configurations achieved indicated-specific engine-out emissions for both soot and nitrogen oxides that comply with current on- and off-road heavy-duty regulations in the United States without exhaust-gas aftertreatment at an intake-oxygen mole fraction of 12%. High-speed in-cylinder imaging of natural soot luminosity shows that some conditions include a second soot-production phase late in the cycle. The probability of these late-cycle events is sensitive to both the number of ducted sprays and the operating conditions.

Non-Intrusive Accelerometer-Based Sensing of Start-Of-Combustion in Compression-Ignition Engines

<div class="section abstract"><div class="htmlview paragraph">A non-intrusive sensing technique to determine start of combustion for mixing-controlled compression-ignition engines was developed based on an accelerometer mounted to the engine block of a 4-cylinder automotive turbo-diesel engine. The sensing approach is based on a physics-based conceptual model for the signal generation process that relates engine block acceleration to the time derivative of heat release rate. The frequency content of the acceleration and pressure signals was analyzed using the magnitude-squared coherence, and a suitable filtering technique for the acceleration signal was selected based on the result. A method to determine start of combustion (SOC) from the acceleration measurements is presented and validated. In-cylinder pressure (used to calculate heat release rate) and accelerometer data were collected on a 1.9-L compression-ignition direct-injection engine (Z19DTH) over a wide range of speeds (1000-3250 RPM) and loads (2-8 bar IMEP<sub>g</sub>), for single- and double-injection strategies, and for fuels of several different cetane numbers (35.5 and 48.5). The relationship between engine block acceleration and the time derivative of heat release rate was verified using the experimental results and indicates that unsteadiness in the rate of heat release is the driving factor for the engine block acceleration signal. The accelerometer-based method developed allows detection of SOC for the main injection with a root mean square error less than 0.75 CAD for the range of conditions tested in this work.</div></div>

An experimental investigation of new chamber geometry on the combustion characteristics, performance and emissions in a light-duty diesel engine

Piston bowl geometry directly affects many parameters such as combustion, flow, turbulence, and mixture formation in-cylinder. This causes a change in engine performance, combustion characteristics and exhaust emissions. In the present study, the effects of piston bowl geometry on mixture formation, combustion characteristics, and emission characteristics of a direct injection compression ignition engine have been experimentally tested. Novel bowl geometries namely New Combustion Chamber (NCC) were developed and made comparison Standard Combustion Chamber (SCC). Air-cooled, four-stroke, single-cylinder and direct injection compression ignition engine was used in the experiments. The diesel engine was operated under full load and different speed conditions (1800, 1900, 2000, 2100 and 2200 rpm). Within the scope of the study, brake specific fuel consumption, engine torque, exhaust emissions (CO2, CO, O2, HC, NO and soot) and combustion characteristics (Instantaneous heat release rate, in-cylinder pressure change, rate of pressure rise and mass fraction burned) were examined. The results showed that the eight pockets and sub-base radius in the NCC geometry significantly improved the specified parameters. The NCC geometry according to the SCC, the specific fuel consumption decreased by approximately 6.89% and engine torque increase 6.32% in the achieved maximum torque at 2000 rpm. Exhaust emissions are generally reduced thanks to the NCC bowl geometry. However, NO emissions increased due to increased temperatures, improved combustion and mixture formation at all speeds. When the combustion analyzes were examined, it was seen that the new type of bowl improved the combustion. The reason was that the increase of the bowl in the surface area, and the increased turbulence with it provided easier evaporation of the fuel droplets and better mixture formation with the air. The spread of combustion over a large area causes an increase in the flame surface area and more controlled combustion was achieved.