Brake Mean Effective Pressure Research Articles

Effects of Ethanol addition to Diesel-Biodiesel blends on the CI engine characteristics

Effects of Ethanol addition to Diesel-Biodiesel blends on the CI engine characteristics

Experimental investigation on the effect of diesel-ethanol blends for a constant-speed diesel engine

ABSTRACT Keeping the need for energy security and the world’s transition to a thriving low-carbon economy in mind, the research, on the feasibility of diesel ethanol blends, has gained momentum. The present work is related to comparing the performance and emission characteristics of pure diesel [D100] with 4 diesel-ethanol blends [D90E10, D85E15, D80E20 and D75E25]. The single-cylinder 4-stroke un-modified diesel engine running at constant 1500 rpm was used for experimentation which ran at different loads. Experimental results showed that with the addition of ethanol in blends, the brake thermal efficiency (BTE) and exhaust gas temperature (EGT) reduced while brake-specific fuel consumption (BSFC) increased. The addition of ethanol shortened the combustion duration. Hence, D75E25 showed a rapid rise in combustion pressure and heat release rate (HRR). As the concentration of ethanol increases in blends, the oxide of nitrogen (NOx) is reduced and carbon monoxide and hydrocarbon (HC) are increased. Thus, D75E5 was good blend producing less NOx with the penalty of fuel consumption on an unmodified diesel engine. In the long run, the effect of blends on the engine should be checked to make ethanol a feasible fuel for diesel engines. Abbreviations: CA: Crank Angle; ATDC: After Top Dead Centre; BMEP: Brake Mean Effective Pressure; BSFC: Brake Specific Fuel Consumption; BTE: Brake Thermal Efficiency; BTDC: Before Top Dead Centre; CO: Carbon Monoxide; COV: Coefficient of Variation; D100: 100% Diesel + 0% Ethanol, Pure petroleum diesel; D90E10: 90% Diesel + 10% Ethanol; D85E15: 85% Diesel + 15% Ethanol; D80E20: 80% Diesel + 20% Ethanol; D75E25: 75% Diesel + 25% Ethanol; HC: Hydrocarbon; IMEP: Indicated Mean Effective Pressure; LHV: Lower Heating Value; NOx: Nitric Oxide.

Experimental investigation of the effect of CO2 dilution on the performance and hydrogen knock limit of a hydrogen–gasoline dual fuel spark ignition engine 1

This study investigates the effect of CO2 dilution on the performance and hydrogen knock limit of a spark ignition engine fueled with hydrogen–gasoline mixtures. The experimental runs were performed on a Ricardo single-cylinder engine with direct gasoline injection and hydrogen port induction. The hydrogen flow rate was increased at a step size of 2 L per minute (LPM) until the onset of knock, and the CO2 gas was introduced to the intake manifold with flow rates of 2, 4, and 6 LPM. The results revealed that CO2 dilution deteriorated the engine performance regarding the brake mean effective pressure and brake thermal efficiency. The hydrogen enrichment shortens the combustion duration, enhancing the performance and combustion characteristics. Increasing CO2 dilution levels decreased NOx emissions and increased CO emissions. Moreover, CO2 dilution extended the hydrogen knock limit to 10 and 16 LPM for spark timings of 12° and 4° crank angles before top dead center, respectively.

Investigation of the performance and emissions of a diesel engine fuelled with bio-oil generated through microwave-assisted pyrolysis of a blend of hazelnut, walnut, and polyethylene terephthalate waste

New and renewable energy sources are the most important issue nowadays. Bio-oil which can replace fossil fuel is an alternative source of energy. In this study, the performance effects and emissions of bio-oil produced by microwave-assisted pyrolysis system (MAP) from the walnut shell (WS), hazelnut shell (HS), and polyethylene terephthalate (PET) waste mixtures on a single-cylinder diesel engine were investigated. For this purpose, WS, HS, and PET wastes were mixed in two different proportions and converted into pyrolytic oil in the MAP system at 700 watts of microwave power and a 30-minute retention time. Produced pyrolytic oils were converted into bio-oil as S1 (46.25% WS + 46.25% HS + 2.5% PET) and S2 (43.75% WS + 43.75% HS + 7.5% PET) through a 3-stage basic upgrading steps. Experimental results showed that MAP of mixed WS, HS, and PET resulted in high hydrocarbon content bio-oil. In the engine experiments, bio-oil was mixed with diesel at 10%, 20%, and 30% ratios by volume and used in a diesel engine at different Brake Mean Effective Pressure (BMEP) (1.4, 2, 2.7, and 3.4 bar). Engine performance has been found to be comparable to diesel at low blend percentages. At 3.4 bar BMEP, while the brake-specific fuel consumption (BSFC) of diesel was 712 g/kWh, it was obtained as 832 and 804 g/kWh at S1 and S2, respectively. However, when the emissions were evaluated in general, it was determined that the emission values increased with increasing bio-oil/diesel blend ratios due to the high viscosity, higher density, and low cetane number of bio-oil compared to diesel.

Dimethyl Ether Biogas Reactivity-Controlled Compression Ignition for Sustainable Power Generation with Low Nitrogen Oxide Emissions

<div>Biogas (60% methane–40% CO<sub>2</sub> approximately) can be used in the reactivity-controlled compression ignition (RCCI) mode along with a high-reactivity fuel (HRF). In this work dimethyl ether (DME) that can also be produced from renewable sources was used as the HRF as a move toward sustainable power generation. The two-cylinder turbocharged diesel engine modified to work in the DME–biogas RCCI (DMB-RCCI) mode was studied under different proportions of methane (45–95%) in biogas since the quality of this fuel can vary depending on the feedstock and production method. Only a narrow range of biogas to DME ratios could be tolerated in this mode at each output without misfire or knock. Detailed experiments were conducted at brake mean effective pressures (BMEPs) of 3 and 5 bar at a speed of 1500 rpm and comparisons were made with the diesel–biogas dual-fuel and diesel–biogas RCCI modes under similar methane flow rates while the proportion of CO<sub>2</sub> was varied. The DMB-RCCI mode exhibited superior brake thermal efficiency (25.3% as against 22% and 31.5% as against 29% at the BMEPs of 3 and 5 bar) as compared to the other modes and was not sensitive to the concentration of methane. The NOx and soot emissions were also negligible and the lowest CH<sub>4</sub> emission levels were also attained. The cyclic fluctuations in IMEP were lower than 5% in this mode. Thus, DME can be used along with biogas to enhance its reactivity for sustainable power generation in the RCCI mode.</div>

Effect of Ammonia Addition on Combustion and Emission Characteristics of Diesel Engine Under Various Operating Conditions

ABSTRACT Ammonia is a carbon-free alternative fuel and a hydrogen carrier. Ammonia diesel dual fuel (ADDF) combustion mode is one of the promising ways to reduce carbon emissions in CI engines. However, present researches are mainly based on combustion and emissions for naturally aspirated diesel engine under specific operating condition. This paper aims to illustrate the impacts of replacing diesel with ammonia in a turbocharged diesel engine under various operating conditions. Hence, the effects of various ammonia substitution rate (ASR) on combustion and emission characteristics are numerically investigate by using GT-Power software for nine groups of different operating conditions with low, medium and high speeds and loads. Results show maximum 70% of input energy can be provided by ammonia for nine groups of different operating conditions, and the brake mean effective pressure (BMEP) and the indicated thermal efficiency (ITE) increases with the increase of ASR. Secondly, increasing ASR decreases the peak cylinder pressure (PCP) under different operating conditions, but increases the maximum pressure rise rate (MPRR) at certain operating conditions. Among them, under medium-speed and high-load conditions, the MPRR reaches the highest value, about 0.587 MPa/(°CA), but does not exceed 0.6 MPa/(°CA). Thirdly, increasing ASR changes the combustion mode from diffusion combustion in pure diesel operation to premixed combustion in dual fuel mode. Finally, adding ammonia reduces the NOx, CO and HC emissions, and the decrease is 15.2%–43.2%, 76.2%–82.3%, 70%–79.6%, respectively.

Performance and CO2 emission of a single cylinder compression ignition engine powered by Khaya senegalensis non-edible seeds fuel blends

This work aimed at investigating blends of Khaya senegalensis biodiesel in a compression ignition engine, attempting to improve engine performance and reduce CO2 emission compared with conventional diesel. Analysis of System (ANSYS) was used to predict in-cylinder behavior of the fuel. ANSYS SpaceClaim generated the geometric model on which 5° sector and mesh refinement was on ANSYS Internal Combustion Engine Modeler (ICEM). Computational domain of interest lies within the compression and expansion strokes. Experimental validation followed: 5% biodiesel, 95% diesel (B5); 15% biodiesel, 85% diesel (B15); 25% biodiesel, 75% diesel (B25); pure diesel (D100); pure biodiesel (B100) in volume proportions. B15 has the highest brake mean effective pressure (BMEP) of 4 bar as load increases. An experimental and numerical comparison reveals pressure declination against speed increment. Ignition temperature fluctuated between 799.76 and 806.256 K for D100 and 760.73–790.62 K for B100 within 1800–2800 rpm speed limit prediction. Power and brake thermal efficiency (BTE) had parallel load increment with all blends. CO2 emission on increasing load conditions were 47.01%, 8.07%, 21.72% and 6.06% for B5, B15, B25, and B100 respectively lower than D100. Pressure and temperature contours gave proper combustion predicted behaviors. All blends possess replaceable performance potential for D100 however, B5 offers better reliable potentials.

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

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

Study on Hydrogen Direct Injection in RNG Combustion under Various Ignition Timings for Power Generation in a Retrofitted Gas Engine

Renewable natural gas (RNG) is attractive for energy policy goals in the world. Therefore, a regional system is designed to explore RNG combustion for power generation in localities. This study investigates a direct injection (DI) engine fueled with hydrogen (H2) blended into the simulated renewable natural gas, which consists of 50% methane (CH4) and 50% carbon dioxide (CO2) in volume. In order to obtain higher efficiency, comparisons between DI and port fuel injection (PFI) of H2 addition were made. Then, the volume percentage of H2 was changed from 20% to 100% by keeping the volume ratio of CH4 and CO2 at 1:1. Finally, results of power output, brake mean effective pressure (BMEP), brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) were discussed. Results showed that in contrast to PFI, H2 DI injection could increase efficiency by 4%. Additionally, H2 DI could retard the MBT ignition timing at 5 °CA. Compared with CH4/CH4 + CO2 combustion, under stoichiometric combustion, BMEP increases with H2 addition but BTE decreases significantly. However, by enlarging the excess air ratio (λ) to 1.24, both BMEP and BTE increase obviously with H2 addition. Moreover, when λ < 1.3, the MBT ignition timing should be advanced from −10 to 15 °CA top dead center (TDC). But the MBT ignition timing is fixed at −25 °CA TDC when λ is larger than 1.3. Furthermore, if efficiency is the priority, 30% H2 addition with λ at 1.24 (−15 °CA TDC) should be selected. If higher BMEP is preferred, 20% H2 addition with λ at 0.99 (−10 °CA TDC) should be selected.

Combustion and emission characteristics of ammonia-hydrogen fueled SI engine with high compression ratio

Ammonia combustion offers the advantage of zero carbon emissions. However, its high ignition energy requirement and slow flame propagation limit its use as an engine fuel. Employing a technological approach that combines a high compression ratio with spark ignition can be beneficial for enhancing ammonia combustion, and this approach warrants further in-depth research. This study investigates the combustion of ammonia within a spark-ignition engine with a compression ratio of 15:1. It enhances combustion by introducing hydrogen as a reactivity-enhancing fuel. Both ammonia and hydrogen are introduced into the engine's intake port. The findings suggest that efficient pure ammonia combustion occurs at low engine speeds (1000 r/min) and high brake mean effective pressure (BMEP exceeding 0.6 MPa). Pure ammonia combustion achieves a brake thermal efficiency of 33.7% at a BMEP of 0.94 MPa. Introducing hydrogen at an energy ratio of 2–16% expands the engine's load range. With hydrogen blending, the efficiency rises to 35.8% at a BMEP of 0.63 MPa. The research on NOx emissions reveals that, under specific operating conditions, there is a reduction reaction between unburned ammonia and NOx, leading to a decrease in NOx emissions as BMEP increases. This study can offer support for the application of ammonia engines.

Influence of phenolic antioxidant additives on performance and emission characteristics of diesel engine fuelled with Jatropha biodiesel: A sustainable hybrid model using RSM and ANFIS

This study aimed to assess the inclusion of antioxidant diphenylamine (DPA) to a Jatropha biodiesel (B30) blend to affects engine performance and exhaust emissions. In this research, three fuel blends has been utilized: diesel, B30, and 100 ppm of antioxidant diphenylamine is added to the B30 blend referred to as B30 + DPA100. A Response Surface Methodology (RSM) has been employed to analyze experimental data, resulting in the development of a regression equation. Additionally, an Adaptive Neuro-Fuzzy Inference System (ANFIS) has been employed to assess and verify the consistency of the developed model. The results from the experiments revealed that the inclusion of the antioxidant had a notable impact on reducing NOx emissions with only a slight effect on brake thermal efficiency (BTHE). Specifically, B30 + DPA100 showed a 7.48 and 15.53% decrease in average NOx emissions, while the average BTHE experienced a modest 0.78% decrease and a 2.67% increase compared to diesel and B30 biodiesel blend, respectively. The Brake Mean Effective Pressure (BMEP) of B30 + DPA100 has been found to be 3.91% and 1.3% higher than diesel and B30, respectively. The Brake Specific Fuel Consumption (BSFC) was 8.68% lower than B30 but 1.49% higher than diesel. Overall, these findings suggest that B30 + DPA100 can be used in diesel engines without modification, offering reduced NOx emissions.

Effect of Fuel Injection Strategies on Performance, Regulated and Unregulated Emissions of a Gasoline Compression Ignition Engine

Abstract Gasoline compression ignition (GCI) mode engines are characterized by partially premixed charge combustion, leading to significant and simultaneous reductions of nitrogen oxides and particulate matter emissions. However, gasoline compression ignition engine operation suffers from a limited operating window. Air preheating and low-research octane number fuels are required to improve the engine performance. This experimental study used a blend of 70% (v/v) gasoline and 30% diesel as test fuel in a direct injection medium-duty compression ignition engine. Experiments were carried out at 5- and 10-bar brake mean effective pressure (BMEP) engine loads at 1500–2500 rpm engine speeds using a triple injection strategy (two pilots and one main injection) for all test conditions. The combustion phasing was kept constant with respect to crank angle to produce a high power output. The investigations examined engine performance and regulated and unregulated emissions. The test engine was initially operated in conventional diesel combustion mode with diesel for baseline data generation. Gasoline compression ignition mode operation demonstrated a remarkable 16% increase in the brake thermal efficiency and a substantial reduction of 65% in nitrogen oxide emissions compared to the baseline conventional diesel combustion mode. The GCI engine exhaust showed higher concentrations of regulated emissions, namely hydrocarbons and carbon monoxide, and unregulated trace emissions, such as methane, acetylene, toluene, inorganic gaseous species, and unsaturated hydrocarbons.

Engine performance and emission characteristics of microwave-produced biodiesel blends

The main objective of this research is to investigate, experimentally, the effects of biodiesel blends on the performance and emissions of a Diesel engine. Measurements were carried out on a single-cylinder, four-stroke, and air-cooled compression-ignition engine, under half and full load conditions. Engine speed was varied from 1000-3000 rpm. Biodiesel was produced by transesterification process of sunflower oil with ethanol, using microwave-assisted heating reactor. Three biodiesel-diesel mixtures: containing 5%, 10%, and 20% by volume of biodiesel, respectively, have been tested and compared to pure diesel fuel. The effects of these biodiesel blends on the engine operating characteristics such as brake specific fuel consumption, brake power, brake thermal efficiency, brake mean effective pressure, and on carbon CO, CO2, and NOx emissions, have been investigated. It was noticed that, at full load, the specific fuel consumptions of biodiesel blends were higher compared to the pure diesel fuel, but no change was observed under ? load. An improvement in the brake thermal efficiency, under ? load, was obtained, but at full load, for medium and high speed, the thermal efficiencies of all biodiesel blends showed a decrease compared to pure diesel fuel. Concerning pollutants emissions, a decrease in CO emissions of all biodiesel blends was noticed. The best result in CO emissions was achieved by the mixture containing 10% by volume of biodiesel with an average reduction value close to 40%. In addition, a significant reduction in NOx emissions was observed for the three biodiesel blends.

Model-Based Calibration and Control of Tailpipe Nitrogen Oxide Emissions in a Light-Duty Diesel Engine and Its Assessment through Model-In-The-Loop

The present paper investigates two different strategies for model-based calibration and control of tailpipe nitrogen oxide emissions in a light-duty 3.0 L diesel engine equipped with an aftertreatment system (ATS). The latter includes a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), and an underfloor selective catalytic reduction (SCR) device, in which the injection of diesel exhaust fluid (DEF), marketed as ‘AdBlue’, is also taken into account. The engine was modeled in the GT-SUITE environment, and a previously developed model-based combustion controller was integrated in the model, which is capable of adjusting the start of injection of the main pulse and the total injected fuel mass, in order to achieve desired targets of engine-out nitrogen oxide emissions (NOx) and brake mean effective pressure (BMEP). First, a model-based calibration strategy consisting of the minimization of an objective function that takes into account fuel consumption and AdBlue injection was developed and assessed by exploring different weight factors. Then, a direct model-based controller of tailpipe nitrogen oxide emissions was designed, which exploits the real-time value of the SCR efficiency to define engine-out NOx emission targets for the combustion controller. Both strategies exploit the model-based combustion controller and were tested through a Model-in-the-Loop (MiL) under steady-state and transient conditions. The advantages in terms of tailpipe NOx emissions, fuel consumption, and AdBlue injection were finally discussed.

Multi-objective optimization of ternary blends of Algal biodiesel-diesel-1-decanol to mitigate environmental pollution in powering a diesel engine using RSM, ANOVA, and artificial bee colony.

This research presents an in-depth examination that utilizes a hybrid technique consisting of response surface methodology (RSM) for experimental design, analysis of variance (ANOVA) for model development, and the artificial bee colony (ABC) algorithm for multi-objective optimization. The study aims to enhance engine performance and reduce emissions through the integration of global maxima for brake thermal efficiency (BTE) and global minima for brake-specific fuel consumption (BSFC), hydrocarbon (HC), nitrogen oxides (NOx), and carbon monoxide (CO) emissions into a composite objective function. The relative importance of each objective was determined using weighted combinations. The ABC algorithm effectively explored the parameter space, determining the optimum values for brake mean effective pressure (BMEP) and 1-decanol% in the fuel mix. The results showed that the optimized solution, with a BMEP of 4.91 and a 1-decanol % of 9.82, improved engine performance and cut emissions significantly. Notably, the BSFC was reduced to 0.29kg/kWh, demonstrating energy efficiency. CO emissions were lowered to 0.598 vol.%, NOx emissions to 1509.91ppm, and HC emissions to 29.52 vol.%. Furthermore, the optimizing procedure produced an astounding brake thermal efficiency (BTE) of 28.78%, indicating better thermal energy efficiency within the engine. The ABC algorithm enhanced engine performance and lowered emissions overall, highlighting the advantageous trade-offs made by a weighted mix of objectives. The study's findings contribute to more sustainable combustion engine practises by providing crucial insights for upgrading engines with higher efficiency and fewer emissions, thus furthering renewable energy aspirations.

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.

Prediction modeling using artificial neural network (ANN) for the performance and emission characteristics of catalytic co-pyrolytic fuel blended with diesel in a CI engine.

In the present research work, artificial neural network (ANN) is used to model the performance and emission parameters in a four-stroke, single-cylinder diesel engine combusting a blended fuel of diesel and catalytic co-pyrolysis oil produced from seeds of Pongamia pinnata, waste LDPE, and calcium oxide catalyst. The optimum yield of oil obtained was 92.5% at 500 °C temperature. Physical properties of the obtained oil, such as calorific value (44.85 MJ/kg) and density (797 kg/m3), level it by that of diesel while the flash point and fire point were found to be lower than that of pure diesel. An ANN model was then generated for the prediction of performance characteristics (BTE and BSFC) and emission characteristics (NOx and smoke) under varying loads, braking power, brake mean effective pressure, and torque as inputs using the Levenberg-Marquardt back-propagation training technique. The regression coefficients (R2) for BTE, BSFC, smoke, and NOx predictions were determined to be close to unity at 0.99859, 0.99814, 0.96129, and 0.92505, respectively (all values being close to unity). It has been discovered that ANN makes an effective simulation and prediction tool for blended fuels in CI engines. It is also suggested to predict the mechanical efficiency, volumetric efficiency, and CO, CO2, HC emissions using ANN in its future work.

Synergic effect of hydrogen and n-butanol on combustion and emission characteristics of a hydrogen direct injection SI engine fueled with n-butanol/gasoline

Hydrogen, an ideal carbon-free energy carrier with favorable combustion properties, has drawn worldwide attention as a high-expectation way to enhance fossil fuels’ combustion performance. However, currently, limited investigations are about enhancing n-butanol hybrid gasoline engines through hydrogen addition. Thus, in this paper, the hydrogen direct injection (HDI) was put forward to improve an SI engine fueled with n-butanol/gasoline, and the synergic effect of hydrogen and n-butanol on combustion and emission characteristics was studied. Experimental results indicated the favorable influence of a low n-butanol mixing ratio (νN, νN = 25%) on enhancing combustion can relatively weaken the similar promoting effect of hydrogen. And the sequential increase in hydrogen addition ratio (φH, φH = 15–20%) can compensate for the negative impact of unfavorable atomization and vaporization quality caused by higher n-butanol blending (νN = 75–100%), namely the usage amount of n-butanol in engine can be raised. Further, compared with pure gasoline, the percentage change in BMEP (brake mean effective pressure) at νN = 25% and 100% can be increased from 1.79% to 5.04% and −5.38%–2.01% respectively by φH from 0 to 20%. Besides, the HDI can also shorten the combustion duration, accelerate the heat release process and improve the combustion stability of each νN, while the amplitude of promotion exhibits a relative downtrend with the increase of φH. As for emission characteristics, the HC, CO and particulate emissions decreased monotonously with the increasing φH under all νN, but there was a visible increase in NOX emissions.

Experimental investigation of ternary biodiesel blends combustion in a diesel engine to reduce emissions

The study presents an experimental investigation of two new ternary biodiesel blends, namely, ManCr_Pa (a mixture of Mandarin, Crambe biodiesel and paraffin as an additive) and AvBn_Pa (mix of Avocado, Bush nut biodiesel and paraffin) by modifying the critical fuel properties closer to the diesel fuel. Those ternary blends' performance, emission and combustion characteristics were compared with diesel and typical B5 blends at the same engine conditions. The result reveals that at high engine rpm, the new ternary biodiesel blends exhibited nearly similar engine performance to that of diesel fuel with a significant reduction of carbon monoxide (33.3%), hydrocarbons (33.3 to 73.3%) and particulate matter (17.8 to 28.8%). For instance, brake power (BP), brake mean effective pressure (BMEP), and brake thermal efficiency (BTE) slightly decreased by 0.25 to 0.38, 0.27 to 0.42 and 0.04%, respectively, whereas brake specific fuel consumption (BSFC) slightly increased by 0.52%. The ternary blends also demonstrated closer combustion behaviour, i.e. heat release rate (HRR) with diesel at full load conditions. Compared with the typical B5 blend, the modified ternary biodiesel blends showed better engine performance with a substantial reduction of emissions. Interestingly, the ternary blends exhibited lower NOx emissions than the B5 blend. The study concluded that the newly developed ternary biodiesel blends are superior to ordinary B5 blends and closely performing fuel to standard diesel. The results of this study have important implications for using these new blends as substitutes for diesel while realising similar benefits.

Estimation of the shape factor (m) in Wiebe function at different operating conditions for a SI engine

The burning process is one of the most important periods, which affects thermal efficiency and exhaust gas emissions, in internal combustion engines. The combustion process in internal combustion engines is modeled with one-dimensional or multi-dimensional software because it is cheaper, faster, and more practical than experiment. One of these methods, which is used to model the combustion period, is the Wiebe function. The Wiebe equation is an approach used in calculating the mass fraction burned and the heat release rate. The selection of Wiebe parameters is one of the most important factors affecting the accuracy of the mass fraction burned. In this study, the measured cylinder pressure of a spark ignition engine was directly used to calculate the heat released rate. The experiments were conducted at different brake mean effective pressures, engine speeds and relative air/fuel ratios, which were called independent variables. The shape factor (m) was determined by fitting the Wiebe equation to the heat release rate curves, which were extracted from the experimental results. The relationship between determined shape factor and independent variables was analyzed with a statistical approach. Eventually, a linear regression model, which explains 80% of the change in the shape factor, was created.