Retarded Injection Timing Research Articles

Experimental investigation of knock control criterion considering power output loss for a PFI SI methanol marine engine

This study presents a new knock control criterion based on different loads and engine power output loss. By utilizing a modified port fuel injection (PFI) spark-ignition (SI) methanol marine engine, the suppressive effects of retarding ignition timing, reducing air-fuel ratio and delaying injection timing on knock intensity at different loads were investigated. Subsequently, a comparative analysis of three knock control strategies was conducted to determine their impacts on power output and thermal efficiency, thus proposing the optimal knock control strategy at different loads. The results show that at both low load (MAP = 73 kPa) and high load (MAP = 139 kPa), the high knock intensity in KLSA (knock-limited spark advance) +5 case is reduced to the safety limitation by retarding ignition timing and reducing air-fuel ratio, while retarding injection timing can effectively suppress knock only at low load. Furthermore, under KLSA+5 condition, there is a significant increase in the probability of severe knock for CA05 earlier than the knock boundary. As the knock tendency is mitigated, IMEP reduces monotonically. There is lower power output loss by optimizing injection timing and air-fuel ratio at low load, and optimizing ignition timing at high load, while the air dilution strategy consistently results in minimal thermal efficiency loss.

Enhancing Combustion Stability in Biodiesel Engines: The Plausibility of n-Butanol Injection Phasing and Reactivity-Controlled Compression Ignition–An Experimental Endeavour

This study explores the synergistic effect of injection phasing on reactivity-controlled compression ignition strategies upon the combustion and stability indices of biodiesel-fuelled single-cylinder four-stroke diesel engines. Mahua Biodiesel was used as the primary fuel, and n-butanol was injected into the manifold to achieve that strategy. The tests were conducted with varying the start of pilot-main injection timing, energy share of biodiesel in split injection and energy share of butanol. This work also entails the various combustion characteristics and the corresponding consequences on the engine’s performance-emission. Ignition delay is shortened with retarded injection timing. At the same time, combustion duration is reduced with higher butanol share and advanced injection timing of biodiesel. The butanol injection and advanced pilot biodiesel injection timing revealed the advancement of combustion phasing. In conjunction with n-butanol port fuel injection, the current study demonstrates the noteworthy and potential superiority of n-butanol as the less reactive constituent. Shortened ignition delay exhibited improved performance and UHC-CO footprint. This study highlights the maximum reduction in regulated emissions compared to operations solely relying on 100% biodiesel. The occurrence of CA50 at 5°–7° CA revealed a maximum decrease in NOX-UHC-CO-CO2 emissions compared to the B100 fuelled strategy. The reduction percentages observed were 53.4%, 97%, 81.1%, and 53.2%, respectively.

Experimental Investigation of Gaseous Emissions and Hydrocarbon Speciation for MF and MTHF Gasoline Blends in DISI Engine

Article Experimental Investigation of Gaseous Emissions and Hydrocarbon Speciation for MF and MTHF Gasoline Blends in DISI Engine Rafiu K. Olalere 1,2, Gengxin Zhang 1, and Hongming Xu 1,3, * 1 Department of Mechanical Engineering, School of Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK 2 Department Mechanical Engineering, Lagos State University of Science and Technology, Ikorodu 02341, Nigeria 3 State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084, China * Correspondence: h.m.xu@bham.ac.uk Received: 8 November 2023 Accepted: 25 March 2024 Published: 28 March 2024 Abstract: With the increasing shortage of fossil energy, the development of engines urgently requires alternative fuels. Gaseous emissions of a gasoline direct injection spark ignition engine fueled with blends of 2-methylfuran (MF 20% vol. and gasoline 80% vol.) and 2-methyltetrahydrofuran (MTHF 20% vol. and gasoline 80% vol.) were experimentally investigated using Gasmeth FTIR. Experiments were conducted at air-fuel ratio (λ = 1) and at engine speed of 1500 rpm using the fuels optimised spark timing. Effects of fuel injection sweeps (180–280 °CA BTDC) on the emission characteristics of blends were investigated at the intermediate load of 5.5 bar IMEP. Hydrocarbon emission (HC) for gasoline is about 41% and 16% higher compared to MF20 and MTHF20 respectively. Carbon monoxide emission for the fuels increases as the injection timing is retarded but the Nitrogen oxide (NOx) emissions was observed to reduce with the retarded injection timing. Both MF20 and MTHF20 recorded high NOx emissions compared to gasoline. The results indicated ethylene (25–26%) as the major component of the HC speciation in the fuels investigated. The unburnt furan samples for blend fuels were determined to be less than 3% of HC emissions, which could be considered a safe level for exposure.

Statistical analysis of Mesua Ferrea seed oil biodiesel fueled diesel engine at variable injection timings using response surface methodology

The twin problems, fossil fuel crisis and the rise in pollution, have activated research in different sources of renewable energy. In this regard, Mesua Ferrea seed oil biodiesel can be a solution which can be employed in diesel engines for power generation and transportation. Keeping this in view, Mesua Ferrea seed oil biodiesel is used in a diesel engine in this investigation. The potential for improvement in performance with varying engine load settings and injection timings is presented in this paper. The statistical investigation was carried out using analysis of variance [ANOVA], response surface methodology [RSM], and desirability-based optimization. A research test engine with a maximum load capacity of 3.5 kW was used for experimentation. Five load settings of engine [20 %, 40 %, 60 %, 80 %, 100 %] and four injection timings [20° BTDC, 23° BTDC, 25° BTDC, 28° BTDC] were employed for the study. Observation of results exhibited that the retarded injection timing of 20° BTDC lowers the emissions and improves the conversion efficiency of fuel for diesel engines powered with Mesua Ferrea seed oil biodiesel. The RSM-based modeling and optimization contributed to the identification of 23.45 % BTE, 49.75 PCP, 25.62 ppm CO, 1.38 % CO2, and 23.38 ppm HC at 20° BTDC FIT and 72.87 % engine load. The RSM-based model forecasted results were examined using a validation test, and the findings were well within 5 % of the model-predicted outcomes, suggesting a robust model.

Effect of injection timing on combustion, emission and performance characteristics of safflower methyl ester in CI engine

Biodiesel, as a renewable fuel, holds great promise, yet its high viscosity presents significant challenges when used in diesel engines. To address these challenges, this study delved into the effects of injection timing on the combustion, emissions, and performance of safflower methyl ester (SAME) in a compression ignition (CI) engine. The experimentation involved testing at three different injection timings: the standard 23° BTDC, advanced 27° BTDC, and retarded 19° BTDC. The results yielded valuable insights. Retarded injection timing notably extended ignition delay by 18 % and reduced the heat release rate by 5 % compared to the standard timing, leading to a substantial decrease in NOx emissions by up to 28 %, a 25 % reduction in CO emissions, and a 5 % decrease in smoke opacity. However, it came at the cost of a 10 % reduction in brake thermal efficiency. Conversely, advanced timing increased NOx emissions by 4 % but concurrently lowered smoke opacity by 3 %. This study underscores the critical importance of optimizing injection timing to balance emissions and performance, mainly when dealing with high-viscosity biodiesels like SAME in diesel engines. The results also highlight the potential of SAME as a viable alternative fuel source, provided that injection timing is judiciously managed to account for its unique viscosity and combustion characteristics. In the quest for sustainable energy solutions, such research is pivotal in harnessing the full potential of biodiesel and advancing its integration into the transportation sector.

Experimental and modeling investigations to improve the performance of the near-zero NOx emissions direct-injection hydrogen engine by injection optimization

High NOx emissions present a significant constraint on the power and efficiency enhancement of direct-injection hydrogen engines. To address this issue, a 2.0 L turbocharged direct-injection hydrogen engine is optimized to achieve near-zero NOx emissions and high engine performance through injection optimization. Both experimental and simulation results indicate that early injection of supersonic hydrogen increases the turbulence energy, while late injection leads to the clustering of rich mixing gases, resulting in elevated combustion temperature and increased NOx emissions. The NOx emissions can keep near-zero while the brake thermal efficiency improves from 40.4% to 41.7% with appropriate retarded injection timing. Therefore, an optimal injection timing exists, and the experiments revealed that adjusting the end timing of injection to 80°CA BTDC resulted in the approximately 1.5% increase in the brake thermal efficiency compared to other injection strategies with near-zero NOx emissions.

Energy, exergy and emission [3E] analysis of Mesua Ferrea seed oil biodiesel fueled diesel engine at variable injection timings

Biofuels can be used in diesel engine for power generation to address the twin problems: fossil fuel depletion and the rise of pollution. In this regard, the present work explores the possibility of enhancement of performance of Mesua Ferrea seed oil biodiesel run diesel Engine through operation at different injection timings and load settings. The investigation is carried out through energy, exergy, and emission (3E) analysis. For experimentation, a research test engine of 3.5 kW is considered. Four injection timings (20° bTDC, 23° bTDC, 25° bTDC, 28° bTDC) and five load settings (20%, 40%, 60%, 80%, 100%) were taken for the test. The results indicate that the retarded injection timing of 20° bTDC results in an improvement of fuel conversion efficiency, as well as a lowering of both exergy destruction and emissions for Mesua Ferrea seed oil biodiesel, run a diesel engine. At injection timing of 20° bTDC for 100% load, the maximum brake thermal efficiencies and maximum exergetic efficiency were found to be 26.11% and 30.32%, respectively under biodiesel mode as compared to 27.76% and 30.74%, respectively for diesel mode. For the same injection timing, the average drop in CO, CO2, and HC emissions were found to be 46.22%, 1.62%, and 39.67%, respectively whereas the average increase of NOX emission was found to be 8.08% in comparison to diesel mode.

Impact of Ignition Assistant on Combustion of Cetane 30 and 35 Jet-Fuel Blends in a Compression-Ignition Engine at Moderate Load and Speed

Abstract This study investigates the use of a commercial-off-the-shelf (COTS) ceramic glow-plug to assist ignition of jet fuel blends with cetane numbers of 30 and 35, below the minimum cetane number of 40 for #2 diesel. Experiments were carried out on a single-cylinder compression-ignition engine operating at 1200 RPM for single and dual-injection (pilot + main) timing sweeps. The COTS glow-plug, termed the ignition assistant, was operated at varying input power levels between 0 and 70 W (stock maximum power input is 30 W) at each SOI. Results demonstrate that the use of an ignition assistant at the higher input powers (50 and 70 W) enables operation over a wider range of SOI timings where more advanced times are limited by high pressure-rise rates and more retarded times are limited by rapidly increasing coefficient of variation of gross indicated mean effective pressure. Use of the ignition assistant enables stable combustion at later injection timings increasing the operable range of SOI timings. For the CN 30 fuel, at earlier injection timings, pressure traces, and heat release analysis demonstrated the advancement of start of combustion and combustion phasing with the ignition assistant on. At retarded injection timings where combustion would not otherwise occur completely for the CN 30 fuel, operating the ignition assistant at the higher powers enabled combustion phasing to be advanced and combustion to be stabilized at conditions where, with the ignition assistant off, misfire (flameout) would occur. Furthermore, the ignition assistant enabled combustion phasing to follow an approximately linear response with respect to SOI timing over a wider range of SOI times.

EXPERIMENTAL INVESTIGATION OF LOW HEAT REJECTION WITH RETARDED INJECTION TIMING ON DIESEL ENGINE USING KARANJA OIL METHYL ESTER

Rising demand for fuel will now pose a significant risk for global pollution levels in various applications. The biodiesel of Karanja oil methyl ester (KOME), an alternative to diesel fuel, is a potential source of unspent fuel in India. Karanja oil contains fatty acid esters, which are environmentally friendly fuel. This experiment aimed to research low heat rejection using Karanja oil methyl ester with retarded injection timing diesel-fueled. The piston, cylinder walls, and engine valves were coated with a 0.5 mm thickness of partially stabilized zirconium (PSZ) without affecting the engine compression ratio. Experiments in the engine with and without coating were carried out using Karanja oil methyl ester. The results showed that Karanja oil methyl ester's specific fuel consumption a retarded timing (RT) with coated engine decreased by 7.4 percent and the brake thermal efficiency improved by 5.5 percent compared to the conventional engine with diesel fuel. CO and UBHC emissions on the LHR with RT engine are lower, whereas the zirconia coating has increased NOx emissions.

Advanced strategies to reduce harmful nitrogen-oxide emissions from biodiesel fueled engine

Advanced techniques have shown an effective approach to reducing nitrogen oxide (NOx) emissions from biodiesel-fueled engines. The primary concern is higher NOx emissions using biodiesel due to its different physio-chemical fuel properties and higher in-cylinder combustion temperatures than diesel. This study aims to scrutinize the existing literature on NOx forming origins from biodiesel and present the state-of-the-art literature on reduction technologies, identify research gaps and introduce further developments to the research opportunities. Accordingly, the present review has organized the technologies into three categories: pre-combustion, combustion, and post-combustion techniques. In addition, the pros and cons of each technique are presented by identifying their role using combustion characteristics. The study identifies that ignition delay and combustion duration are the major factors to consider in reducing NOx emissions. Applying innovative tactics to modify the fuel, chamber, and injection parameters prolongs the ignition delay and combustion duration, thereby reducing NOx emissions. Furthermore, exhaust gas after-treatment systems with novel catalytic convertors have shown a strong capability of reducing NOx emissions. The findings also indicate significant reductions in NOx emissions from biodiesel with provided technologies; however, a clear roadmap is needed to integrate these technologies for sustainable application. The study concludes that emulsion techniques, low-temperature combustion strategies, retarded injection timing, and exhaust gas after treatment have shown significant NOx reduction through reduced peak temperature rates. The study recommends further investigation on reactive controlled combustion techniques as they directly impact NOx emission, and their results comparisons will give a clear understanding for deriving better commercial options.

An experimental investigation on ceramic coating with retarded injection timing on diesel engine using Karanja oil methyl ester

Rising demand for fuel will now pose a major risk for global pollution levels in various applications. The biodiesel of Karanja oil methyl ester (KOME), an alternative to diesel fuel, is a potential source of unspent fuel in India. The goal of this experiment was to research low-heat rejection using Karanja oil methyl ester with retarded injection timing diesel-fuelled. With 0.5 mm thickness of partial stabilised zirconium (PSZ), the piston, cylinder walls and engine valves were coated without affecting the engine compression ratio. Experiments in the engine with and without coating were carried out using diesel or Karanja oil methyl ester. The results showed that the specific fuel consumption for Karanja oil methyl ester with a retarded timing-reduced engine decreased by 7.4% and the brake thermal efficiency improved by 5.5% compared to the conventional engine with nice diesel fuel.

Experimental and numerical study of split injection strategy on balancing the ultra-lean burn and high compression ratio engine design

In this study, the aim of split injection is to strike a balance between the ultra-lean burn mode and high compression ratio method by experimented and numericized. Under ultra-lean condition, no matter single injection mode or split injection mode, both knock percentage and combustion stability does not monotonically decrease with the retarded injection timing. Considering the combustion stability and knocking, first injection timing of 300 oCA BTDC and second injection timing of 190 oCA BTDC is choose as optimized strategy, which achieves knock frequency of 16 % and COVIMEP of 3.69 %. Based on optimized injection strategy, the indicated specific fuel consumption achieves 184.53 g/KWh. With the split injection, a deeper ultra-lean burn can be achieved without the severe knock and combustion fluctuation and obtain ultra-low NOx emissions of 2.8 ppm. The numericized result also demonstrates that because of the ultra-lean conditions, the flame grows more slowly, and then the temperature of the un-burn zone rises significantly as a result of the primary flame stream. Meanwhile, the propagation speed to the exhaust valve side appears to be substantially slower than in other directions. As a result, auto-ignition can be seen near the exhaust valve. When using split injection, the flame kernels do not propagate as fast and deep as in the case of single injection because of the cooling effect. This drops temperature in the unburned end-gas region and thus reduces knocking tendency.

Prediction of split injection strategy assisted diesel engine combustion, performance and emission characteristics fuelled waste frying oil methyl ester through central composite design

The objective of this study is to use response surface methodology to forecast the performance, combustion, and emission characteristics of an advanced injection strategy-assisted diesel engine running on waste frying oil methyl ester. The experiment was carried out on a diesel engine using a high-pressure fuel injection system. The main injection timing ranges varied from 16 to 24 °CA bTDC, whereas the post-injection ranges from −6 °CA bTDC to 6 °CA aTDC. The injection quantity for the main and post injections quantity varied from 70 % to 90 %, 10 % to 30 %, and the injection pressure is set at 500 bar. Experiments were carried out using a design matrix developed by the design of experiments. At 100 % load, B100-90 %-10 % obtained the highest BTE of 33.87 % and the lowest fuel consumption of 0.268 kg/kW-hr. At the main injection timing of 22 °CA and post-injection timing of −4 °CA, D100-80 %-20 % achieved the lowest unburned hydrocarbon, Smoke emission of 13 ppm, and 1.613 FSN respectively. The point prediction approach was used to forecast the combustion and emission parameters of a diesel engine, and the predicted results were in good agreement with the experimental results. Furthermore, when compared to advance injection timing for biodiesel fuel, retarded injection timing reduces nitric oxide emission. The Split injection strategy is one of the most effective techniques to reduce soot and NO × emissions while maintaining diesel engine efficiency.

Application of pilot injection strategies for enhanced ignition and combustion of a low reactivity fuel in a compression-ignition engine

• Pilot injection can enhance combustion of a low reactivity fuel. • Pilot mixtures merging with main jet is a cause for studied mixture conditions. • Earlier pilot injection achieves enhanced reaction for studied mixture conditions. • Higher pilot proportion and shorter pilot-main dwell have higher effects. • HCHO formation is higher and its consumption to form OH is increased. The impact of pilot injection on ignition and combustion of a low-reactivity fuel is systematically investigated in an optically accessible light-duty compression-ignition engine. The role of key pilot-main injection control parameters, including the pilot injection timing, proportion and pilot-main injection dwell time, is found through line-of-sight integrated high-speed imaging of cool-flame and OH* chemiluminescence signals as well as planar laser-induced fluorescence imaging of formaldehyde (HCHO-PLIF) and hydroxyl (OH-PLIF). This suite of diagnostics enables visualisation of low-temperature reaction and high-temperature reaction during the extended ignition delay period of a selected low reactivity fuel with only 30 cetane number. The results show significant combustion enhancement associated with the pilot-main injection strategy for all injection timings tested. The enhanced ignition is most effective in the case of retarded injection timings with almost misfiring single injection operation recovered for stable and strong combustion due to the pilot mixture merged with the main fuel jet. This enhancement effect is further promoted when the proportion of pilot injection mass to the total fuel mass is increased or the dwell time between the pilot and main injection is decreased as the pilot mixture interaction with the main fuel jet is enhanced. Compared to the single injection, measured HCHO-PLIF signals are higher and OH-PLIF signals develop at a higher rate due to the pilot injection, indicating the pilot mixture addition enhanced both the low-temperature reaction and high-temperature reaction of the tested low-reactivity fuel.

Experimental Investigation on Effects of Fuel Injection Timings on Dimethyl Ether (DME) Energy Share Improvement and Emission Reduction in a Dual-Fuel CRDI Compression Ignition Engine

The impacts of different fuel injection timings (base (15BTDC) and retarded (12BTDC)) on a single cylinder common rail direct injection (CRDI) compression ignition (CI) engine under dual fuel mode (DME-diesel) was examined at the maximum torque with the engine speed of 2200 rpm. The diesel (liquid) fuel was directly injected into the engine’s cylinder at the end of the compression stroke and Dimethyl ether (gas) fuel was injected into the intake system of the engine during the suction stroke. The maximum DME energy share (DME ES) with base injection timing (15BTDC) under controlled auto-ignition (CAI) is limited to 52%. Delayed injection timing prevents knock occurrence to a certain extent due to the lower peak combustion pressure and temperature. The DME energy share (DME ES) without knocking is extended to 58% with delayed injection timing (12BTDC). Three stages of combustion (low-temperature region, high-temperature region and diffusion combustion region) were observed under DME-diesel mode. The low-temperature region (LTR) occurs at the temperature range from 700–900 K whereas high-temperature region (HTR) was at the temperature beyond 1000 K. The cyclic variations with the coefficient of variation (COV) of the important parameters (peak in-cylinder pressure, peak rate of pressure rise and indicated mean effective pressure) were analyzed. NOx emission decreased along with zero smoke emission. However, the other emissions such as CO, HC increased marginally with retarded timing. The notable point emerged from this study is that the retarded injection timing is a promising strategy for enhancement of DME energy share with reduced emissions.

Effects of swirl enhancement on in-cylinder flow and mixture characteristics in a high-compression-ratio, spray-guided, gasoline direct injection engine

In this study, the flow enhancement effects of applying a swirl control valve were investigated with particle image velocimetry and simulation using CONVERGE v2.4 program in a high compression ratio, spray-guided, gasoline direct injection engine. This was followed by analysis of varying the spray structure and the mixture preparation process for different swirl control valve angles. The flow intensity was strengthened in the order of swirl control valve angle 45°, 30°, and 0°, and spark plug gap velocities near TDC were increased 1.89, 4.40, and 6.69 m/s in that order. However, the effect was not significant when it was increased to more than 45°. Also, the swirl-dominant flow and the tumble-dominant flow were differentiated based on the relationship between maximum swirl and tumble ratios. In the swirl dominant flow (swirl control valve angle of 0°), more retarded injection timing produced mixture formation in the order of homogenous to mal-distributed to stratified, whereas in the tumble dominant flow (swirl control valve angle of 45°), the order was homogenous to stratified to mal-distributed. It was determined by characteristic period to which the injection timing belonged, and the characteristic period was defined based on the relationship between the intake valve lift and the piston velocity.

Parametric study of the impact of EGR and fuel properties on diesel engine performance using a predictive thermodynamic model

This paper presents a detailed quasi-dimensional model that can assist in the design process as it allows predicting the performance and emissions of compression ignition (CI) engines functioning with different fuels, such as kerosene and Diesel. The proposed model includes a new dedicated fuel injection mass flow rate sub-model that is coupled to the multi-zone spray packet concept for spray development. Moreover, fuel spray development and its interaction with in-cylinder swirl is considered and allows studying the influence of combustion chamber design, fuel injection strategy, as well as fuel properties. The model is validated against single and double injection strategies using kerosene and diesel fuels and is shown to be capable of predicting engine performance with a good accuracy. The results obtained from the parametric studies have shown proper trend with respect to the effect of the bowl-to-bore diameter ratio, EGR rate and temperature or fuel properties. This latter predicts that fuels with higher lower heating values (LHVs) can decrease NO and soot emissions by using retarded injection timing, while the boiling temperature has a small effect on the evaporation and mixture formation process. Finally, a fuel with a high enthalpy of vaporization can achieve lower soot emissions by increasing the swirl ratio or increasing the injection timing although doing so is detrimental to the power output.

Optimization of combustion parameters for CRDI small single cylinder diesel engine by using response surface method

Limited fossil fuel’s reservoir capacity and pollution caused by them are the big problem today in the world. The small diesel engine, working with a conventional fuel injection system was the major contributor to this. The current study represented a statistical investigation of such a small diesel engine. A mechanical fuel injection system of the small diesel engine was retofitted with a simple version of the electronic common rail diesel injection (CRDI) system in the present study. The effect of combustion parameters such as compression ratio (CR), injection pressure (IP) and start of injection timing (IT) was considered in the study. The study was performed to optimize these parameters with respect to performance and emission aspects. The reduction in parameters such as carbon monoxide (CO), nitrogen oxides (NOx), smoke and hydrocarbon (HC) from engine exhaust gases were considered in the emission aspect. Improve brake thermal efficiency (BTE) and fuel economy was considered in the performance aspect. The response surfaced method (RSM) was used to optimise these combustion parameters. The regression equations were obtained for measurable performance and emission parameters using the RSM model. The surface plots derived from the regression equations were used to analyse the effect of considered combustion parameters. Diesel injected at a pressure 600 bar, with retarded injection timing 15° crank angle (CA) before top dead center (bTDC) and compression ratio set at 15 was found to be optimum for this CRDI small diesel engine. The further validation of optimum parameters was done by conducting a confirmatory test on the engine. The maximum error in prediction was found to be 2.7%, which shows the validation of the RSM model.

Application of Oxygenated DEE and Ethanol on the Performance and Emission Characteristics of Diesel-Fuelled CI Engine in the Context of Variable Injection Timing

In a direct injection CI engine, the ignition delay and combustion characteristics are very sensitive to changes in fuel injection timing as the peak pressure and temperatures change significantly close to TDC. The addition of DEE and ethanol to diesel fuel causes retarding of the dynamic injection timing. Hence, it desires to study the effect of variable injection timing on emission and performance of DEE-ethanol-diesel blended CI engine and find out the optimum injection timing. In this experimental study, the optimum performance DE8E10D (8% DEE, 10% ethanol and 82% diesel by volume) blended fuel is selected for investigation. The engine tests are carried out at no load, 25%, 50%, 75% and 100% of full load with 3° and 6° advancement, base injection timing and 5° retarded injection timings. The test results reveal that BTE has improved and the smoke, CO and HC emissions have reduced with advanced injection timing. At full load condition, the 6° advancement in injection timing has reduced the smoke by 10.66% than the base injection timing. A sharp decrease in NOx emissions has been observed in 5° retard in injection timing. Overall, the results validate that 6° advancement is the optimum injection timing which has improved the overall performance and emissions of DEE-ethanol-diesel blend fuel in the CI engine.

Influence of 1-pentanol as the renewable fuel blended with hydrogen on the diesel engine characteristics and trade-off study with variable injection timing

Biofuels are considered as one of the best viable and inexhaustible alternatives to conventional diesel fuel. Alcohols have become very important and popular in the present scenario due to their characteristic fuel properties and production nature. This study examines the influence of 1-pentanol and hydrogen on various performance characteristics of CRDI diesel engines. The experiment was carried out with a load range of 25%–100% in 25% percent increments, at 1500 rpm constant engine speed. The influence of injection-timing at 9°, 12°and 15°bTDC was first investigated using 30% 1-pentanol as fuel to observe the effect on engine parameters in comparison with base fluid. Compared to conventional and retarded injection timings, 1-pentanol displayed better emission and performance characteristics at higher injection timings. Additionally, at 15°bTDC, 30% 1-pentanol was used with 12 LPM hydrogen in a dual fuel mode. Compared to plain diesel, the hydrogen-enriched fuel resulted in a 1.50% lower HRR (heat release rate) and 6.77% higher cylinder pressure at 75% load. Thus, it is evident that hydrogen enrichment at 75% load effectively reduces hydrocarbon and nitrogen oxide emissions by 6.66% and 10%, respectively, and improves thermal efficiency by 5%. The experiment revealed that 1-pentanol performs effectively at higher injection timings and that hydrogen improved the performance even further. Furthermore, the long-term viability of hydrogen and 1-pentanol as an energy source is well demonstrated in future scenarios.