Fuel Injection Pressure Research Articles

Study the effect of injection pressure of a mixture of diesel fuel and vegetable oil on exhaust emissions of diesel engines by simulation

Biofuels are interested in using alternative fuel in diesel engines because those are friendly to the environment and can be recycled. However, characteristics of chemical and physical differences compared to diesel fuel. While using the fuel injection system of an engine must be adjusted. Computational Fluid Dynamics KIVA-3V software allows simulation of the working cycle of the engine with injection pressure effect. This paper presents the results of a simulation study of B15 biofuel used on the 4CHE Yanmar diesel engine, and the fuel injection pressure was adjusted at 210, 220, 230, and 240 bar within the limits of high-pressure pump adjustment. The results showed that the soot emissions of the engine were lowest at 230 bars.

On the effect of injection pressure on spray combustion and soot formation processes of gasoline/second generation biodiesel blend

70GB, which comprises 70% gasoline and 30% biodiesel, shows excellent potential for application in gasoline compression ignition due to its superior lubrication capability, renewability, environmental friendliness, high ignitability contributed by biodiesel namely as Hydrogenated catalytic biodiesel (HCB), and high volatility conferred by gasoline. However, the spray combustion and emission characteristics of 70GB fuel have not yet been quantitatively evaluated. In this work, we performed a comprehensive simulation focusing on the ignition delay, heat release rate, flame lift-off length, flame structure, and soot formation of 70GB in a constant volume chamber under various fuel injection pressure. Numerical results showed that, different injection pressure strongly impact the HRR without affecting the maximum temperature. Increasing the injection pressure from 80 to 120 Mpa, increased the heat release rates by 23. %. The ignition delay was marginally affected by increasing injection pressure, while a 5.7 mm increase in flame lift-off length observed with higher injection pressure. Additionally, 65% lower soot formation was typically predicted for higher injection pressure 120MPa. In particular, the soot mass is primarily controlled by enhancing the atomization and evaporation processes, as well as improving fuel-air mixing rate, which was achieved by increasing the injection pressure. Furthermore, the role of soot oxidation was insignificant in reducing soot with increasing injection pressure, while the soot initiation step and soot surface growth step play an important role in soot suppression with increasing injection pressure for 70G fuel.

Characteristics of the transient heat transfer of impinging flames and correlation analysis using a new characteristic velocity under CI engine-like conditions

Understanding the transient heat transfer mechanism of impinging flames is a crucial pathway for further improving the thermal efficiency of already efficient compression ignition (CI) engines. In this paper, the investigation of the transient heat transfer of wall-impinging flames was performed in a high-pressure constant-volume vessel. Fast-response thermocouples were installed in the impinging wall to record the transient heat flux. Two-color pyrometry was employed to estimate the mean temperature inside the flame region. Firstly, the transient heat transfer characteristics were investigated under varied ambient density, oxygen concentration, temperature, and injection pressure conditions. The optical flame velocity calculation method was applied to this extensive dataset to develop a heat transfer correlation between Nu and Re with which transient heat transfer coefficients were calculated and compared with the experimental results. From this analysis, cumulative fuel injection velocity was developed as the new characteristic parameter to characterize the transient heat transfer of the wall-impinging flames. Results indicate that the effect of fuel injection pressure on the heat flux is more significant than that of ambient gas conditions, with higher injection pressure causing higher heat flux through the impinging wall. No obvious linear tendency of transient Nu and Re was found when using the optical measurement results of the wall-impinging flame as the characteristic parameter. Instead, the cumulative fuel injection velocity shows a strong linear trend of transient Nu and Re during the transient heat transfer processes of the wall-impinging flame. Moreover, the heat transfer coefficients from the new cumulative fuel injection velocity well fit the experimental results.

Organic carbon, elemental carbon and particulate semivolatile organic compound emissions from a common-rail diesel engine: Insight into effect of fuel injection pressure at different loads

Effect of fuel injection pressure on organic carbon (OC), elemental carbon (EC) and particulate semivolatile organic compounds (SVOCs), i.e., n-alkanes and polycyclic aromatic hydrocarbons (PAHs), emissions from a common-rail diesel engine was analyzed comprehensively. EC emission rate evidently decreased with increasing injection pressure at low fuel injection pressure ranges (80–120 MPa), while engine load effect on the EC emission was insignificant at high injection pressure ranges (140–160 MPa). The higher fraction of EC2 in the total EC emission appeared at the highest injection pressure ranges (140–160 MPa) under middle and high loads, suggesting the spontaneous carbonization process from soot precursor to ordered soot during the high temperature process. Low injection pressure provided poor combustion condition and caused unburned diesel fuel to volatilize more 2–3 ring PAHs. The percentage of 4-ring PAHs exhibited a rise-then-fall trend with increasing injection pressure, while the maximum percentage of 5–7 ring PAHs appeared at the highest injection pressure ranges (140–160 MPa) under high load condition, suggesting that higher combustion temperature and larger pyrolysis zone under the high injection pressure promoted the formation of lager and more stable PAHs. The fractions of fuel-derived short chain (C16-C21) and oil-derived long chain (C22-C33) in the total n-alkanes exhibited obvious load and injection pressure dependence.

Macroscopic and microscopic spray characterisation of Low-Octane blends for gasoline compression ignition engines

Gasoline compression ignition is an advanced combustion technology that controls harmful emissions from low-octane fuels used in compression ignition engines. Fuel’s physical properties and injection strategy influence the fuel–air mixture formation and combustion. High volatile fuel and fuel injection pressure improve the spray atomisation and fuel–air mixture formation. Gasoline-diesel blends are widely investigated for gasoline compression ignition engine applications. This study investigated microscopic and macroscopic spray characteristics of 70 % v/v gasoline and 30 % v/v diesel blend (G70), 80 % v/v gasoline and 20 % v/v diesel blend (G80), and baseline diesel injected at different fuel injection pressures. Parameters such as liquid fuel spray penetration length, spray cone angle, and droplet size and velocity distributions were assessed. The results of these parameters help determine the effect of the fuel injection parameters on combustion. It was found that though the liquid spray penetration length was not significantly different for the three test fuels, G70 exhibited a slightly lower liquid spray penetration length than the other two test fuels. Increasing the diesel fraction in the test blend reduced the spray cone angle and improved the axial dispersion of the fuel spray. The spray droplet diameter reduced with increasing gasoline fraction in the test blend and the fuel injection pressure. Sauter mean diameter decreased by up to 20 % for G80 than baseline diesel and up to 36 % with an increased fuel injection pressure from 300 to 700 bar. This study addressed a significant research gap in the spray characteristics of gasoline-diesel blends and provided a benchmark for simulation based model validation.

Application of an explainable glass-box machine learning approach for prognostic analysis of a biogas-powered small agriculture engine

Biogas has developed as a potential substitute fuel source due to its renewable and sustainable nature, which can help reduce greenhouse gas emissions. In this paper, along with the experimental investigation, a novel interpretable expert system was constructed to address these issues and provide meaningful explanations for model predictions using extreme gradient boosting (XGB). For this purpose, the SHapley Additive exPlanations (SHAP) tool was coupled with XGB open-source algorithm to simulate five efficiency parameters of the biogas-powered engines, including brake thermal efficiency (BTE), peak pressure (PP), hydrocarbon (HC), oxides of nitrogen (NOx), and carbon monoxide (CO). Here, four experimental-based variables comprised of fuel injection timing, fuel injection pressure, compression ratio, and engine load were employed as predictors. Apart from the main framework, two advanced ensemble machine learning (ML), namely the light gradient-boosting machine (LightGBM) and Extra Tree algorithms, were adopted to validate the primary model. In addition, we use the SHAP framework to understand the impact of input features on engine performance and emission outputs. XGB-SHAP owing to its best predictive performance (BTE|R = 0.994 and RMSE = 0.567, PP|R = 0.984 and RMSE = 0.846, HC|R = 0.994 and RMSE = 6.215, NOx|R = 0.998 and RMSE = 1.407, and CO|R = 0.985 and RMSE = 3.464) outperformed the Extra Tree and LightGBM, respectively.

Theoretical study of the effect of fuel injection start pressure on the characteristics of the combustion process, indicators, and braking efficiency of the 2CH10.5/13 type engine

Introduction: Over time, demands on internal combustion engines are increasing, with a focus on fuel efficiency, emissions reduction, improved reliability, and cost-effective production and operation. Studying diesel engines like the 2CH10.5/13 is relevant due to their significant potential in the modern world. The purpose of study is to investigate the theoretical effect of the initial fuel injection pressure on the combustion process, engine braking performance and efficiency. Materials and Methods: The paper describes the methods of choosing injectors for diesel engines with a high-pressure fuel system. Results and Discussion: Using mathematical calculations and modeling is an effective means to prevent engine operation issues. Developing a dedicated calculation method is necessary to understand the impact of diesel fuel ignition volume on engine performance parameters. The results of experimental studies, which included non-motorised, motorised, and operational tests of diesel nozzles, are also presented. Studies have shown that after 4,000 cumulative hours of operation, the residual life of the injector nozzles is insignificant, since the dynamic performance of the diesel engine decreases to the limit value (7%). Conclusions: This may indicate the need for regular maintenance and replacement of nozzles in accordance with the manufacturer’s recommendations.

Estimation of the potential of Nahar biodiesel run diesel engine at varying fuel injection pressures and engine loads through exergy approach

Power production, as well as transportation, are two sectors mainly contributing to global warming and pollution. These effects can be lessened through the use of biofuels. However, biofuels are plagued due to low calorific value and high viscosity compared to diesel. However, this can be overcome by proper adjustment of the operating parameters (Compression ratio, Fuel injection timing, Fuel injection Pressure, Engine load). The present study tries to unravel the influence of fuel injection pressure on the performance, combustion, emission, and exergy analysis of the Nahar biodiesel run diesel engine. Five fuel injection pressure (200 bar, 220 bar, 240 bar, 260 bar, 280 bar) and five engine loading conditions (20 %, 40 %, 60 %, 80 %, 100 %) at injection timing of 23° BTDC and compression ratio of 17.5 are considered. The results indicate that the performance, combustion, emission, and exergy parameters improve with the use of higher fuel injection pressure. The maximum BTEs are found to be 24.86 %, 27 %, 28.11 %, 29.22 %, and 31.13 % in biodiesel mode at FIPs of 200 bar, 220 bar, 240 bar, 260 bar, and 280 bar, respectively in comparison to 27.76 % for diesel at standard settings (FIP = 200 bar, CR = 17.5, IT = 23° BTDC) at 100 % load. Furthermore, the effect of addition of nanoparticles and variation of other operating parameters such as injection timing and compression ratio of the engine may enhance the performance and emissions of Nahar biodiesel run diesel engine.

Visualization study on ammonia/diesel dual direct injection combustion characteristics and interaction between sprays

Ammonia is regarded as a highly promising green fuel. Nevertheless, its auto-ignition temperature is exceptionally elevated, posing challenges for its direct utilization in compression ignition engines. Using highly active fuel as the ignition source seems a solution. In this paper, based on the RCEM experimental platform, the diesel/ammonia diffusion combustion mode was studied in detail. The experimental parameters included the ammonia injection pressure, ammonia and diesel injection interval (including ammonia in advance of diesel and diesel in advance of ammonia), diesel injection pressure, and ammonia nozzle diameter. The results indicated that injecting ammonia on diesel flame contributed to the completeness of ammonia combustion. Injecting ammonia before diesel achieved a higher peak heat release rate but aggravated the incomplete combustion. The injection pressure of diesel had no significant impact on the combustion effect of ammonia. Increasing the ammonia injection pressure resulted in enhanced air entrainment, consequently enhancing the effective combination of fuel with air, which improved the peak heat release rate more effectively. Increasing the diameter of the ammonia nozzle was a necessary way to achieve a high ammonia energy substitution ratio, but a large amount of ammonia sprayed simultaneously caused a portion of the ammonia to not burn in time, resulting in aggravation of incomplete combustion. In addition, the interaction between diesel spray and ammonia spray was also studied. The results showed that, due to the higher quantity of ammonia compared to diesel, the two sprays would gather and develop toward the direction of ammonia injection roughly, and the final development direction of the spray was also related to the fuel injection pressure.

Effects of Injection Pressure on Performance and Emission Characteristics of CI Engine using Waste Cooking Oil (WCO) Blend

For a long period of time, vegetable oil cannot be used directly in a direct injection diesel engine. The tolerance tests may indicate significant problems. The outcome of Injection Pressures (IP) on the performance and emissions of a diesel engine powered by waste cooking oil biodiesel were explored in this study. It is investigated and standard diesel results are compared to the performance characteristics and emission studies of a single cylinder, four-stroke, direct-injection diesel engine fueled with used cooking oil in 20% (on a mass basis) blends. This study established the appropriateness of using cooking oil. The experiment consisted of running at a constant speed of 1500 rpm and then loaded gradually. The tests were conducted at 5 different loading are 0%, 25%, 50%, 75%, and 100% of the load in kW, with compression ratios of 17.5:1. The result of adjusting the injection pressure to 185–235 bars with a gap of 25 bars, with the original IP set at 210 bar. Fuel injection pressure is critical in improving engine performance and emission characteristics. The diesel engine ran on Waste Cooking Oil (WCO) at various injection pressures, including 185 bars, 210 bars, and 235 bars. The engine tests were carried out to examine how a diesel engine operating on a WCO20 biodiesel blend performed and produced emissions at varied injection pressures. Except for NOx, biodiesel blends at 235 bars injection pressure performed better and had lower emissions than those at 185 bars injection pressure. Without any modifications, the optimal fuel blend can be considered for a compression ignition engine.

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.

Performance and emission characteristics of double split injection biodiesel engine with intake air throttling

Most diesel engines typically operate with high excess air in part load. Implementing air intake restriction with exhaust gas recirculation (EGR) could be a viable option for mitigating NOx emission and soot, particularly when utilizing biodiesel, attributing to biodiesel's inherent oxygen content. This study examines the effect of intake air throttle and EGR coupled with split injection strategies on a turbocharged 4-cylinder engine fuelled with B60-POME fuel. A parametric test was conducted to examine the impact of fuel injection pressure, intake air throttling and EGR, followed by Response Surface Methodology (RSM) optimisation. When EGR is implemented with a 45% intake throttle opening, a relatively low EGR rate of 5% is achieved. A study utilising RSM was conducted to optimise the control of air supply and split injection parameters, involved with a total of 6 control variables. The optimum parameter appears at a dwell angle of 12 °CA, SOI timing of −4°ATDC, 40% intake throttle opening, EGR of 6.75%, fuel injection pressure of 800 bar and split injection ratio of 50%. These settings yield prediction emission results that are closely similar to those obtained from the actual confirmation test.

A sustainable model using RSM and MCDM techniques to evaluate performance and emission characteristics of a diesel engine fueled with diphenylamine antioxidant and CeO2 nanoparticle additive biodiesel blends

Overconsuming fossil fuels has worsened global warming and air pollution, requiring us to investigate alternate fuels for compression ignition engines. Biodiesel is a renewable fuel and environmentally favorable. Biodiesel's most significant disadvantage is increased nitrogen oxide (NOx) emissions. The intent of the present study was to examine the impact of antioxidant diphenylamine (DPA) and nanoparticle ceria (CeO2) additive inclusion in a B30 blend on engine performance and exhaust emission characteristics. For this study, diesel, Jatropha biodiesel (B30), 100 ppm of antioxidant diphenylamine (50 ppm) with ceria nanoparticle (50 ppm) is added to the B30 blend named as B30+DPA100 and antioxidant diphenylamine (50 ppm) with ceria nanoparticle (50 ppm) is added to the B30 blend named as B30+DPA50+CeO250 fuel blends has been used. A hybrid response surface methodology and multi-criteria decision-making techniques (entropy method, TOPSIS, and VIKOR) have been used to develop a sustainable model and find the optimal setting of input parameters in terms of ranking. From experimental findings, the inclusion of antioxidants (DPA) and nanoparticle (CeO2) at 50 ppm to B30 significantly reduced NOx emission. The brake-specific fuel consumption and NOx have been found reduced by 5.67% and 18.87%, respectively, for B30+DPA50+CeO250 as compared to B30. At the same time, brake thermal efficiency increased by 1.01%. The brake mean effective pressure and maximum cylinder pressure) have been found increased by 0.68% and reduced by 4.52%, respectively, for B30+DPA50+CeO250 as compared to B30. The alternative ranking of the input parameters has been found fuel injection pressure (300), compression ratio (17), and load (12) as Rank 1 for TOPSIS and VIKOR. Therefore, the B30+DPA50+CeO250 blend is appropriate for improving diesel engine performance and diminishing exhaust emissions.

Reactive Flow Dynamics of Low-Frequency Instability in a Scramjet Combustor

This study numerically investigated the combustion instability and characteristics of a laboratory-scale gaseous hydrogen-fueled scramjet combustor. For this purpose, a numerical simulation with an improved detached eddy simulation and a detailed hydrogen/oxygen reaction mechanism was performed. The numerical framework used high-resolution schemes with high-order accuracy to ensure high resolution and fidelity. A total of five fuel injection pressures were considered to characterize the combustion instability as a function of the equivalence ratio. A sampling time of up to 100 ms was considered to sufficiently accumulate several cycles of low-frequency combustion instability dynamics with a period in the order of 100 Hz. Numerical results revealed the repetitive formation/dissipation dynamics of the upstream-traveling shock wave, and it acts as a key factor of combustion instability. The period and derived principal frequency of these upstream-traveling shock waves is several ms. The frequency analysis showed that the instability frequency increased in the low-frequency range as the combustion mode transitioned from the cavity shear-layer to the jet-wake type. This characteristic was derived from the transition in combustion mode at the same equivalence ratio. Therefore, it suggests that the instability frequency shifting is governed by the combustion mode rather than the equivalence ratio. These comprehensive numerical results demonstrated not only the effect of the equivalence ratio but also the important role of the combustion mode on the low-frequency combustion instability.

Maximizing efficiency and environmental benefits of an algae biodiesel-hydrogen dual fuel engine through operational parameter optimization using response surface methodology

The utilization of clean and renewable fuels has become increasingly significant in the power generation and transportation sectors. Dual-fuel engines that employ hydrogen and algal biodiesel are potential alternatives. This study investigated the impact of pilot fuel injection pressures and engine loads on the performance and emissions of an algal biodiesel-hydrogen dual-fuel engine. The engine was optimized using response surface methodology under various operating conditions. The highest brake thermal efficiency (28.71 %) was obtained at 240 bar pilot fuel injection pressure and 100 % engine load, significantly reducing carbon monoxide and hydrocarbon emissions. The optimum parameters were identified using response surface methodology at 67.63 % engine load and 245.48 bar pilot fuel injection pressure, with a high model fit (R2) range of 88.89 %–99.59 % and composite desirability of 96.1 %. The potential for optimizing algal biodiesel-hydrogen dual-fuel engines to achieve greater efficiency and environmental benefits is highlighted in this work, as is the relevance of applying response surface methods to optimize engine performance.

Process optimization of IC engine testing: SiO2 nanoparticle dosed Azolla methyl ester

AbstractNanoparticles are now widely used in biodiesel‐diesel combinations for improving the engine performance and reduction of emissions. This present study investigates the Bio‐silica (Silicon‐dioxide, SiO2). The statistical and experimental study demonstrates the utilization of various levels of SiO2 in Azolla Biodiesel blend (ABD) with appropriate engine parameters such as fuel injection pressure, fuel injection timing and compression ratio for minimal emissions and optimal performance employing response surface approach. In a mixture of Azolla biodiesel and diesel, SiO2 nanoparticles were utilized at quantities of 25, 50, and 75 ppm. To determine the existence of Silicon‐dioxide, the produced nanoparticles were subjected to tests such as XRD, SEM, TEM, and EDS. The Response Surface optimizer was used with DOE L29 array and the engine predictors with a desirability value of 0.6180, were18.5°bTDC (IT), 238 Bar (IP), 17.1237 (CR), and 45.885 ppm SiO2 nanoparticle. The results were determined to be fit statistically and with high assurance levels. Thus, the addition of SiO2 nanoadditives along with aquatic fern Azolla oil methyl ester reduced the emission without affecting the engine performance.

Experimental investigation of near-field spray characteristics of RP3 aviation fuel based on multivariable sensitivity and uncertainty analysis

The utilization of aviation kerosene RP3 in diesel engines and ground vehicles has attracted more attention due to the implementation of the army's Single Fuel Concept. To explore the characteristics of the RP3 near-field spray primary breakup, experimental studies were carried out via the diffuser back-illumination imaging (DBI) method under single-hole injectors accommodated to varied engine spray circumstance. The critical factors of the variability in RP3 spray characteristics response were figured out by constructing a one-dimensional active subspace to perform multivariable synergistic effects via sensitivity analysis. Moreover, the uncertainties associated with unstable cavitation within nozzle were quantified with a varied array of operating conditions. In comparison to diesel, it is indicated that, there is a range of critical cavitation, in where greater uncertainties in spray cone angles are exhibited, especially for RP3. RP3 tends to form a ‘mushroom’ spray structure, with a smaller spray cone angle compared to diesel, but the disparity gradually diminishes as the fuel injection pressure increases. The gradual transition from ‘needle’ to ‘mushroom’ shape in RP3's near-field spray structure is revealed with increased fuel injection pressure, and the appearance time of the ‘mushroom’ structure advances with higher ambient pressures. Based on the active space construction, the sensitivity analysis discovers that the spray cone angle is dominantly influenced by ambient pressure and cavitation within the nozzle, thus providing a new perspective on analyzing test data without the expense of single variable statistical work.

Modelling and optimisation of VCR diesel engine parameters fuelled with microalgae methyl-ester: a RSM-coupled Taguchi approach

ABSTRACT Due to the high consumption of fossil fuels and their environmental effects, researchers are attempting to develop clean and environmentally sustainable alternative fuels. This study employs a hybrid statistical approach, combining the Taguchi approach and Response Surface Methodology (RSM), to optimise the input parameters of a diesel engine operating on microalgae methyl ester in order to increase engine performance. Through the execution of L16 pre-designed experiments, this work analyzes the significance of three key process parameters: engine load (25-50-75-100%), fuel injection pressure (200-210-220-230 bar), and microalgae biodiesel blends (B20-B40-B50-B100) with respect to brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), carbon dioxide (CO2), and nitrogen oxides (NOx). The response surface methodology was utilised to conduct an experimental investigation. At 71.52% of the engine load, a 204.23 bar injection pressure and a microalgae biodiesel blend of 20% (B20) were found to be the optimal input parameters. The optimum setting of the input parameters provides responses of 31.83% BTE, 278.658 g/kWh of BSFC, 872.053 g/kWh of CO2, and 1725.57 ppm volume of NOx, respectively. The experimental and predicted responses were compared, and it was found that the optimised values were within acceptable limits, with an error of less than 6%.

Fuel temperature and injection pressure influence on the cold start GDI sprays

Cold start in gasoline direct injection engines (GDI) is a critical issue that significantly impacts fuel consumption and emissions. Therefore, it is essential to investigate and improve the spray and air-fuel mixing processes during cold starts. This study employed a complimentary set of optical diagnostic techniques, including line-of-sight(extinction, Schlieren, and long-distance microscopy) and 3D computed tomography (CT), to characterize and understand the cold-start spray dynamics under various fuel temperature and injection pressure conditions. The experiments were conducted in a constant volume spray vessel and the fuel temperature was varied using a coolant circulator, with temperatures reaching as low as -7 °C to simulate cold-start conditions. The cold fuel exhibited longer liquid/vapor penetration lengths compared to hot fuel under low injection pressure conditions. This deterioration in spray characteristics was attributed to the attenuated fuel evaporation and reduced entrainment of ambient air. The 3D spray visualization obtained through the CT algorithm, particularly the cut plane images, revealed that plumes with low fuel temperatures had narrower individual plume widths, resulting in minimized plume-to-plume interaction. Microscopic imaging further confirmed this observation which showed separate plumes in the near-nozzle region for cold fuel conditions. Meanwhile, hot fuel under high injection pressure conditions exhibited complete plume collapsing, leading to a significant amount of liquid fuel remaining in the spray core. The liquid penetration reached 70 mm during the injection period, potentially can cause wall wetting on the piston top or cylinder wall. Based on the experimental findings, this study suggests the application of multiple injections with a moderate level of injection pressure for optimized engine performance and reduced emissions during cold starts.

Engine vibration and noise characteristics of common rail direct injection engine fuelled with orange peel oil by response surface methodology based multi-objective optimization

The present study aims to find out the noise and vibration & compatibility of OPO (orange peel oil) in the common rail direct injection engine. Various injection strategies like FIP (fuel injection pressure), pilot mass, pilot injection timing, and engine speed are examined at idling mode using the design of experiments software. The obtained results are post-processed and computed in the form of perturbation and surface plots based on RSM (response surface methodology) and analysis of variance. Considering the trade-off with combustion parameters, the engine speed is found to be more responsible for crank level vibrations while FIP created more influence in head level vibrations. OPO B20 (20% OPO + 80% diesel by volume) injected 28° CA bTDC (before top dead centre) is predicted to be optimum by using RSM. In the case of diesel fuel, vibrations at the head level show a noticeable increase in all three directions as the FIP is raised. However, when using a OPO B20, the vibrations primarily in the z-direction are significantly affected by the FIP changes. Additionally, for OPO B20 fuel at idling operation, the pilot mass of 20%, engine speed at 979 rpm, and a fuel injection pressure of 300 bar are the optimal setting condition to achieve favourable characteristics of combustion, vibration and noise.