Compression Ignition Diesel Engine Research Articles

Combined Effect of CNG and EGR on the Performance, Emission and Combustion Characteristics of Diesel Engine in Dual Fuel mode

Severe and adverse energy crises in future, day by day ever elevating cost of fuels, dangerous emissions emitted with conventional fuels made internal combustion engine scientists to discover and look at the likelihood of usage of alternate, clean and less or zero emissions fluids and vaporous fuels for IC engines, especially compression ignition diesel engines (DE) since existing DE are under stringent pollutions regulation that too for smoke and NOx in their tail pipe fumes. The main target of this work is to examine the emission, combustion and performance attributes of a diesel engine running with a wide range of loads with a constant speed of 1500rpm with a 30% steedy energy share of CNG and varying EGR of 5%,10% and 15% using diesel as pilot fuel. BSEC of dual fuel mode engine is discovered superior to neat diesel engine mode at higher load. It is discovered that there is an uncommon decrease in NOX, CO2, and smoke density, increment in UHC, CO in the fumes of dual fuel engine at all loads. Comparative results are given for dual fuel mode with variable measures of EGR at various loads conditions and detailed the impact of the application of EGR on combustion, performance and emission processes.

A study on split diesel injection on thermal efficiency and emissions of an ammonia/diesel dual-fuel engine

Ammonia is gaining more interest as a carbon-free alternative fuel in freight transportation applications, especially the shipping industry. However, the problems of nitrous oxide (N2O) emissions, which has almost 300 times higher global warming impact than carbon dioxide (CO2), and ammonia slip have been the main challenges of using ammonia in compression ignition (CI) diesel engines. In this study, the effect of split diesel injection strategy (i.e., two-pulse diesel injection) on an ammonia/diesel dual-fuel (ADDF) engine is investigated under medium load operating conditions. Results indicate that the ADDF combustion mode with single diesel injection strategy achieves lower indicated thermal efficiency (ITE) compared to the corresponding diesel-only combustion mode. However, the use of split diesel injection strategy increases the ITE of the ADDF combustion mode to 39.72% which is higher than that obtained by diesel-only combustion mode (maximum ITEdiesel = 38.62%). Moreover, split diesel injection strategy reduces the unburned ammonia emissions of the ADDF combustion mode by up to 83.5% compared to the lowest unburned ammonia emissions achieved by single diesel injection strategy. Two split diesel injection strategies based on the optimum points of greenhouse gas (GHG) emissions are suggested in this research. At the first optimum point, the GHG emissions of the ADDF combustion mode are decreased by 23.7%, while ITE is increased by about 2% compared to the optimum point of diesel-only combustion mode. This, however, comes with about 10% higher nitrogen oxides (NOx) emissions. The emitted GHG emissions of ADDF combustion can be further reduced by 30.6%, but at the expense of 2.2% lower ITE and 52.4% higher NOx emissions than diesel-only combustion mode. At both optimum points, unburned ammonia emissions were significantly reduced to below 900 ppm compared to that of ADDF combustion mode with single diesel injection strategy (i.e., 4445 ppm). The lowest unburned ammonia concentration achieved in this study is still above the recommended exposure limit and therefore the use of appropriate after-treatment devices should be considered in the future.

Experimental study on combustion and unregulated emission characteristics of a diesel engine fueled with light hydrocarbon/diesel blends

Rigorous emission regulations are provoking to pursue substitute of diesel with clean and sustainable alternative fuels to work out the problem of the regulated and unregulated emissions and diesel depletion. In this paper, the partial load characteristics of emission especially unregulated and combustion characteristics of a six-cylinder compression ignition diesel engine fueled with conventional diesel and 85% light hydrocarbon (LHC)-diesel blends were investigated and compared at the load points of 50%, 75% and 100% and the speed of 1000 rpm. Gas chromatography-mass spectrometry (GC–MS) technology was utilized to identify components of both tested fuel and unregulated emissions. The cylinder pressure, pressure rise rate, indicated power, heat release rate and emissions were comparatively analyzed between these two fuels. The gaseous pollutants including NOx, CO and total hydrocarbon (THC) are determined by gas analyzer. Based on the experimental results, blending LHC extend the ignition delay period, thus leading to its combustion phase lag behind that of diesel fuel by 3°CA. Significant reduction in specific NOx and CO emissions was noted while THC emission is higher in engine fueling LHC/diesel blends. The dominant unregulated pollutants primarily include organosilicon compounds (OSC), aromatic compounds (AC), and non-aromatic hydrocarbons and their derivatives (NAHC). The determinant factors on OSC emissions are summarized into the content of antifoaming agents in lubricants and the load conditions. The AC emissions of both fuels have an ascending tendency with the increase of load and the AC emissions of LHC/diesel blends are obviously less than that of pure diesel. The NAHC emissions usually appear under higher load conditions with regard to LHC blends and the content is far lower than that of diesel. In a word, blending diesel with LHC significantly contributes to improve both combustion and emission characteristics.

Physical-oriented and machine learning-based emission modeling in a diesel compression ignition engine: Dimensionality reduction and regression

The development of internal combustion engines is affected by the exhaust gas emissions legislation and the striving to increase performance. This demands for engine-out emission models that can be used for engine optimization for real driving emission controls. The prediction capability of physically and data-driven engine-out emission models is influenced by the system inputs, which are specified by the user and can lead to an improved accuracy with increasing number of inputs. Thereby the occurrence of irrelevant inputs becomes more probable, which have a low functional relation to the emissions and can lead to overfitting. Alternatively, data-driven methods can be used to detect irrelevant and redundant inputs. In this work, thermodynamic states are modeled based on 772 stationary measured test bench data from a commercial vehicle diesel engine. Afterward, 37 measured and modeled variables are led into a data-driven dimensionality reduction. For this purpose, approaches of supervised learning, such as lasso regression and linear support vector machine, and unsupervised learning methods like principal component analysis and factor analysis are applied to select and extract the relevant features. The selected and extracted features are used for regression by the support vector machine and the feedforward neural network to model the NOx, CO, HC, and soot emissions. This enables an evaluation of the modeling accuracy as a result of the dimensionality reduction. Using the methods in this work, the 37 variables are reduced to 25, 22, 11, and 16 inputs for NOx, CO, HC, and soot emission modeling while maintaining the accuracy. The features selected using the lasso algorithm provide more accurate learning of the regression models than the extracted features through principal component analysis and factor analysis. This results in test errors RMSETe for modeling NOx, CO, HC, and soot emissions 19.22 ppm, 6.46 ppm, 1.29 ppm, and 0.06 FSN, respectively.

Investigation the combined effects of exhaust gas recirculation (EGR) and alcohol-diesel blends in improvement of NOX-PM Trade-off in compression ignition (CI) diesel engine

The increasing demand to decrease the greenhouse gas emissions leads to find clean fuel and renewable fuel such as ethanol and methanol that good replacement of oil-derived transportation fuels. The combined effects of alcohols blends (ethanol-diesel and methanol-diesel) and with and without EGR on NOX-PM Trade-off in diesel engine were investigated under variable engine loads and speeds. The EGR is considered efficient technology to reduce the NOX emissions in compression ignition (CI) diesel engines. The current study highlighted on the trade-off between nitrogen oxides (NOX) and particulate matter (PM). The oxygenating content in the ethanol blend (E10) and methanol blend (M10) decrease the PM concentrations in the exhaust pipe compared to the diesel fuel for different engine operating conditions with keep NOX emissions in the moderate level. It was found that the NOX/PM concentrations significantly decreased from the combustion of E10 and M10 under variable engine loads and speeds.

Experimental analysis of diesel fuel properties with blended Mahua oil biodiesel for CI engines

The experimental research work done here in this study reveals the consequence of biodiesel blending on the characteristics of CI (diesel) engine and its performance. In this paper Biodiesel obtained from Mahua oil is experimented, its preparation is through the two-step transesterification process in the presence of low molecular weight alcohols for example methanol and a base such as sodium hydroxide. Research experiments were conducted so as for the evaluation of the experimental performance parameters of a 1-cylinder, water-cooled and four strokes, direct injection Compression Ignition (CI) engine with the above mentioned specially prepared Mahua oil for better results. The experiments were observed with thrice attempts and the results obtained from all the fuel blends were thoroughly formulated, analysed and compared with clean mineral diesel available in the market used in automotive sector.

Experimental investigation of the impact ethanol-biodiesel-diesel blended fuels on combustion, emission, and performance of compression ignition diesel engine

This research was directed to reduce the global diesel engine emissions and dependency on finite fossil fuel reserves. The ethanol was blended by weight ratio with commercial “B20” fuel (20% palm oil’s biodiesel and 80% diesel) as B20E5 (95% B20 with 5% ethanol), B20E10 (90% B20 with 10% ethanol) and B20E20 (80% B20 with 20% ethanol). The results of the engine’s performance, combustion, emission, and agglomerate particles size using blended fuels were compared with the results of based commercial B20 fuel. All fuel samples were tested on a four-cylinder direct injection diesel engine at a constant load of 140Nm with engine speeds of 1000RPM, 1500RPM and 2000RPM. When the engine speed increased, the brake-specific fuel consumption decreased, and the brake thermal efficiency increased. The B20E20 shows the highest brake-specific fuel consumption because of the low energy content of the fuel blend and the highest thermal efficiency because of a better combustion process. The ethanol-blended fuels show higher peaks of in-cylinder pressure and heat release rate than the base B20 fuel, with B20E20 as the highest. Ethanol blended fuels have significant advantages in particulate matters reduction, especially in idle engine speed. The blended fuels decreased soot and CO2 emissions and increased NOx emission. The agglomerate particles size distribution was analysed with 100 samples for each fuel by using Scanning Electron Microscopy (SEM) and Image J tools. The average agglomerate particle size of B20, B20E5, B20E10 and B20E20 are 0.253 µm, 0.245 µm, 0.225 µm and 0.187 µm, respectively. As conclusion, adding ethanol to diesel fuel provide strong advantages on soot reduction and higher engine efficiency due to the enrich of fuel oxygen.

Vibration, acoustic and emission characteristics of the chlorella vulgaris microalgae oil in compression ignition engine to mitigate environmental pollution

The petroleum fuel demand with high price and its exhaustion imposes a pressure to find an alternative. The fossil fuel shortage has been deteriorating over the past few years, because of the rapid increase in population. Many attempts have been made to increase the quality of biofuel with additives. In this paper, two types of nanoparticles such as carbon nanotubes (CNT) and alumina (Al2O3) in chlorella microalgae biofuel were analyzed by experimental method. The added CNT and alumina act as a catalyst that induces complete combustion with retarded emissions. In addition to above, the noise and vibration qualities are also measured. A series of test conducted using single cylinders, four stroke, naturally aspirated compression ignition diesel engine was run by using pure diesel and also different fuel blends ‘such as B10CNT50A50 Chlorella (Microalgae Biodiesel 10% + Diesel 90% + CNT 50 ppm), B20CNT50A50 (Microalgae Biodiesel 20% + Diesel 80% + CNT 50 ppm + Al2O3 50 ppm) and B30CNT50A50 (Microalgae Biodiesel 30% + Diesel 70% + CNT 50 ppm + Al2O3 50 ppm). At a constant load condition, all experimental tests were conducted at four different speeds such as 1500 rpm, 2000 rpm, 2500 rpm and 3000 rpm. The reference fuel of diesel B0 results was compared with blended fuel. From the results, it has been found that the nano additives of CNT and alumina reduced the greenhouse gas emissions of CO compared to plain diesel. Only considering the blended fuel, as the percentage of biofuel increases, the emission of nitric oxide and carbon dioxide is decreased with significant reduction in the amount of noise and vibration and also the combustion and performance qualities were also improved. The highest benefit in terms of all factors was achieved in the fuel blend of B30A50CNT50 amongst the other blends.

Non-monotonic change of ignition delay with injection pressure under low ambient temperature for the diesel spray combustion

The impact of injection pressure on the startability of compression ignition (CI) diesel engines has not been thoroughly studied yet, especially for the startup at low-temperature conditions. This research investigates the effects of injection pressure on diesel spray and flame characteristics under low ambient temperatures (close to the critical ignition temperature of diesel spray) in a constant volume combustion chamber (CVCC) using Schlieren, Mie scattering, and direct photography. Different from past engine startability research, the ignition delay time under quasi-critical ignition temperature is measured to be first shortened then prolonged with increasing injection pressure. The primary cause of such phenomenon is analyzed to be the trade-off effects between spray atomization and heat convection from the fuel to the ambience, which is quantitatively validated by the analytical calculation based on the Arrhenius-type correlation.

Combustion Performance Investigation of Aviation Kerosene (RP-3) on a Compression Ignition Diesel Engine Under Various Loads

Abstract The combustion performance of a compression ignition (CI) four-stroke aviation engine fueled with pure kerosene No. 3 rocket propellant (RP-3) was experimentally investigated for comparison with diesel. Pilot injection and main injection for RP-3 and diesel were unified under same test conditions. The results show that when burning RP-3, the maximum power of engine is 1% lower than that of burning diesel, with lower specific fuel consumption (SFC) and effective thermal efficiency (ETE). The combustion durations of RP-3 and diesel show small differences of less than 0.4 °CA under heavy loads, while the combustion duration of RP-3 is shorter than that of diesel under low loads. The crank angle at 50% mass fraction burnt (CA50) of RP-3 shows differences of 0.3–1 °CA compared with that of diesel. For pilot injection at a high engine speed, the ignition delay angle (IDA) of RP-3 is basically equal to that of diesel. With decreasing engine speed, the maximum difference of 1.2 °CA in IDAs exists under medium or small loads. For the main injection, the IDA of RP-3 is larger than that of diesel under heavy loads at various engine speeds. As the load decreases, the IDA of RP-3 is extended. The peak heat release rate (HRR) of RP-3 during main injection combustion is basically the same as that of diesel under heavy loads, while the intervention effect of unburnt pilot-injected RP-3 under low loads results in a higher peak HRR.

Experimental and kinetic modelling studies on di-n‑butyl ether (DBE) low temperature auto-ignition

Di-n‑butyl ether (DBE), mainly derived from lignocellulosic biomass, is a long-chain linear ether that is regarded as a promising alternative for diesel in compression-ignition engines. Therefore, understanding of the auto-ignition characteristics of DBE is of great importance. In this work, ignition delay times (IDTs) of DBE/O2/N2 mixtures were experimentally measured on a rapid compression machine (RCM). The experiments were conducted at the compressed temperatures ranging from 525 to 707 K, the compressed pressures at 7 and 10 bar, and the equivalence ratios of 0.7, 1.0 and 1.4. A negative temperature coefficient (NTC) behavior was observed for the total IDTs in the tested temperature range. The effects of compressed temperature, compressed pressure, fuel fraction and oxygen fraction, on both the first-stage and total IDTs, were also discussed. Validated against the experimental measurements, two existing DBE chemical kinetic models were found to have less satisfactory performances for the IDT prediction. Therefore, a tuned model based on the Thion model was presented, and it was found to well capture the fuel NTC behaviors and improve the IDTs prediction at the test conditions. Moreover, the tuned model was tested against the measurements on IDTs and species mole fraction profiles in the literature. The tuned model reasonably predicts the measured IDTs on a shock tube at high temperatures and on a flow reactor at low temperatures. The double-NTC behavior of DBE oxidation observed in jet-stirred reactor (JSR) and plug flow reactor (PFR) experiments can be also reasonably predicted.

A Study on Performance Evaluation of Biodiesel from Grape Seed Oil and Its Blends for Diesel Vehicles

With incessant increases in fuel prices worldwide and concerns for environmental pollution, the need for alternative sources of energy is becoming urgent. In this study, the potential of grape seed oil for biodiesel as an alternative fuel was evaluated. Refined grape seed oil was bought in liquid form and then subjected to an alkali-catalyzed transesterification process for biodiesel production. The physicochemical properties of the resulting biodiesel—namely, viscosity, cetane number, and heating value—were investigated. The biodiesel was blended with a conventional diesel in various proportions and combusted in a four-cylinder, four-stroke compression ignition (diesel) engine under two loading conditions. Experimental results revealed that the blend ratio of B70 (70% GS biodiesel and 30% conventional diesel) gave the best overall engine performance in terms of maximum power, minimum emissions, and fuel consumption. Furthermore, a novel neural network technique called extreme learning machine was adopted to investigate the optimal blend ratio using the dataset obtained from the experimental results. The results also indicate that the best choice of biodiesel blend ratio is approximately B73.67 (73.67% GS biodiesel and 26.33% conventional diesel). The study shows that grape seed oil could serve as a reliable source of production of quality biodiesel fuels, which could be used as an alternative to conventional diesel fuels.

Numerical investigation on combustion and emissions in a direct injection compression ignition engine fuelled with various hydrogen–methane–diesel blends at different intake air temperatures

Blending hydrogen and methane with diesel in compression ignition engines has been proven to improve both performance and emissions. This work further explores the combustion characteristics and emissions of a direct injection compression ignition (DICI) engine fuelled with various blend ratios of hydrogen, methane and diesel with respect to varying intake air temperatures, as the blend ratio can affect the mixture formation process in such high-speed in-cylinder phenomena. A numerical study using ANSYS Fluent was conducted based on a 0.406-litre Yanmar L100AE-D single-cylinder DICI engine running at 1500 rpm and was verified with a physical experiment using the same engine. The tri-fuel blend consisted of 60% diesel by mass with the remaining 40% made up with various ratios of hydrogen and methane (0%/40%, 12%/28%, 20%/20%, 28%/12%, and 40%/0%). The intake air temperatures were varied at 303 K, 318 K and 338 K, representing near-standard, high and extremely high ambient air temperatures, respectively. The results showed that the presence of methane and hydrogen in diesel fuel resulted in a higher in-cylinder pressure, temperature and heat release rate (HRR). Increasing the intake air temperature caused a proportional increase in the in-cylinder temperature, pressure and HRR. However, the presence of methane lengthened the ignition delay, while increasing hydrogen reversed the trend. While the presence of hydrogen–methane reduced the overall CO emissions, the effect of hydrogen on CO reduction was dominant. In addition, the presence of hydrogen–methane led to an increase in NOx emissions due to the high combustion temperature. The study suggested that an optimized intake temperature and the balanced use of tri-fuel in a direct injection compression ignition engine can significantly improve engine performance and emissions.

A Study on Fundamental Combustion Properties of Oxymethylene Ether-2

Abstract Oxymethylene ethers (OMEn, n = 1–5) are a promising class of synthetic fuels that have the potential to be used as additives or substitutes to diesel in compression ignition engines. A comprehensive understanding of their combustion properties is required for their safe and efficient utilization. In this study, the results of a combined experimental and modeling work on oxidation of OME2 are reported: (i) Ignition delay time measurements of stoichiometric OME2/synthetic air mixtures diluted 1:5 with nitrogen using the shock tube method at pressures of 1, 4, and 16 bar, and (ii) laminar flame speeds of OME2/air mixtures using the cone angle method at atmospheric and elevated pressures of 3 and 6 bar. The experimental data sets obtained have been used for validation of three detailed reaction mechanisms of OME2 obtained from literature. The results of ignition delay time measurements showed that ignition of OME2 is characterized by pre-ignition activity at the low temperature side of the measurements regardless of the pressure. Regarding the performance of the different reaction mechanisms, the model from Cai et al. (2020, “Auto-Ignition of Oxymethylene Ethers (OMEn, n = 2–4) as Promising Synthetic e-Fuels From Renewable Electricity: Shock Tube Experiments and Automatic Mechanism Generation,” Fuel, 264, p. 116711) best predicted the temperature and pressure dependence of ignition delay times. For laminar flame speeds, the experimental data were well matched by the mechanism from Ren et al. (2019) at p = 1, 3, and 6 bar and for all equivalence ratios considered. From sensitivity analyses calculations, it was observed that chain reactions involving small radicals, i.e., H, O, OH, HO2, and CH3 control the oxidation of OME2. The comparison of the results of this work and our previous work (Ngugi et al. (2021)) on OME1 show that these two fuels have similar oxidation pathways. The results obtained in this work will contribute to a better understanding of the combustion of oxymethylene ethers, and thus, to the design and optimization of burners and engines as well.

Hydrogen and propane implications for reactivity controlled compression ignition combustion engine running on landfill gas and diesel fuel

A detailed investigation of employing landfill gas together with additives such as hydrogen or propane or both as a primary low reactivity fuel in a reactivity controlled compression ignition combustion of a diesel engine is conducted. A 3401E caterpillar single-cylinder diesel engine with a bathtub piston bowl profile is utilized to execute the study. The engine is operated at various intake pressures of 1.6, 1.9, and 2.2 bar, and runs at a fixed engine speed of 1300 rpm. For verification purposes, the conduct of the present engine running on pure methane as a low reactivity fuel is compared to that of the same engine available in the literature. Next, a numerical simulation is made to assess the performance of the present engine running on landfill gas plus the additives. Based on the obtained results, injecting either hydrogen or propane or a combination of both up to a total amount of 10% by volume to the premixed of landfill gas and air, and advancing diesel fuel injection timing of about 20–30 deg. crank angle, render the landfill gas utilization quite competitive with using methane alone. Applying an enriched landfill gas in a reactivity controlled compression ignition diesel engine, as a power generator, drastically reduces the greenhouse gas emission to the atmosphere. Also, the CO and UHC mole fraction in the exhaust gas can be eliminated by either advancing the start of diesel injection or using hydrogen or propane or both as additives. In addition, utilizing hydrogen or propane or a combination of both with the primary fuel improves the peak pressure to about 16% in comparison with that of landfill gas alone.

Development of a reduced primary reference fuel-PODE3-methanol-ethanol-n-butanol mechanism for dual-fuel engine simulations

Polyoxymethylene dimethyl ethers (PODEn) have attracted worldwide attention, which could be adopted as an alternative or additive of diesel in compression ignition engines. This work focuses on the implementation of PODE for dual-fuel engine combustion. The effects of four dual-fuel combinations on the engine combustion performance and emissions were studied, including PODE-isooctane, PODE-methanol, PODE-ethanol, and PODE-n-butanol. First, a new reduced mechanism of primary reference fuel-PODE3-methanol-ethanol-n-butanol was developed and validated. This mechanism was then employed for the three-dimensional numerical investigation. The results demonstrated that at an exhaust gas recirculation (EGR) rate of 45%, PODE-n-butanol and PODE-isooctane generated higher thermal efficiencies than PODE-methanol and PODE-ethanol, primarily due to the higher reactivity of n-butanol and isooctane compared to methanol and ethanol. The highest thermal efficiency of 47.0% was obtained using PODE-NC4H9OH with a start of injection timing of −7.5°. With an EGR rate of 52%, NOx emissions of all cases met the regulation limit, which, however, were achieved at a sacrifice of engine efficiency; additionally, the highest thermal efficiency of 43.3% was achieved using PODE-CH3OH with an injection timing of −17.5°.

Increase of efficiency and reduction of CO and NOx emissions in a stationary compression ignition engine run on Mesua ferrea Linn oil-diesel and diethyl ether

In this study, Mesua ferrea Linn oil (VO, 30% by volume)-diesel (70% by volume) blend (VO30) is used as the fuel to power a direct-injection (DI), single-cylinder compression ignition (CI) diesel engine. This study is focused on the effects of diethyl ether (DEE) as an additive on the performance, combustion and emission characteristics of the engine fuelled by the VO30 blend. DEE is added to the VO30 blend to form two types of ternary blend. One consists of 5% DEE and 95% VO30 by volume (VO30DEE05) and the other consists of 10% DEE and 90% VO30 by volume (VO30DEE10). The study reveals an improvement of 1% to 2.3% in engine thermal efficiency with the use of diethyl ether as additives to the VO-diesel blend. In the same line, both the CO and NOx emission also decreases with the use of DEE additives with the VO-diesel blend. A maximum reduction of 6.9% to 13% CO emission and 3.2% to 11.9% NOx has been achieved with DEE additives as compared to VO30 fuel. The work suggests that DEE can be used effectively as an additive to VO30 fuel which can run CI diesel engines with improved thermal efficiency and reduced emissions.

Investigation of the impact of injection timing and pressure on emissions characteristics and smoke/soot emissions in diesel engine fuelling with soybean fuel

Engine injection strategy and renewable fuel both can improve nitrogen oxides (NOX) and smoke/soot emissions in a common-rail compression ignition (CI) diesel engine. The effects of different postinjection (PI) timings (15, 30, and 45) after top dead center (aTDC) and injection pressures (550 and 650 bar) on pollutant emissions and smoke/soot emissions were investigated for combustion of a renewable fuel (soybean biodiesel). The results showed that the levels of carbon monoxide (CO), hydrocarbons (HCs), and NOX are reduced from the combustion of soybean biodiesel compared to the diesel fuel combustion for different injection strategy. Besides, NOX emission is clearly reduced with retarded PI timing, especially at 45°. It is found that the increasing injection pressure reduced gaseous emissions for both fuels. The combination between biodiesel fuel and injection strategy can provide meaningful improvements in pollutant emissions, as well as enhance the exhaust temperature compared to the diesel fuel. With biodiesel fueling, smoke/soot emissions were reduced from biodiesel combustion (by 19.7%) under different fuel injection timings and pressures rather than from the diesel fuel combustion (by 12.2%).

Dual fuel ethanol port injection in a compression ignition diesel engine: Technical analysis, environmental behavior, and economic viability

The increase in prices, dependence on fossil fuels, and concerns about greenhouse gas emissions, and strict emissions regulations have motivated researchers to look for low carbon renewable fuels for internal combustion engines. Ethanol is one of these fuels due to its presence in the energy matrix of several countries. Among the methods applied to use ethanol in compression ignition engines, the primary technique currently studied is port fuel injection (PFI). This research studies the feasibility of using ethanol as a partial fuel in a generator set analyzed beyond the technical and environmental parameters and the economic aspect. The experiments were conducted in a diesel single-cylinder engine, with its original diesel fuel direct injection system, and added an auxiliary PFI system for the ethanol supply. The research gap is based on the lack of studies that include, in addition to the analysis of performance parameters and gaseous emissions, the economic viability assessment for the studied engine, which is also a fundamental factor in an actual application. The engine was tested under different conditions of six progressive replacements of diesel fuel by ethanol, starting only with diesel fuel (baseline test) and increasing ethanol mass fraction up to 0.634. The measured data showed that ethanol effectively increased ignition delay and reduced combustion duration, which did not lead to increased efficiency and reduced fuel consumption. The maximum in-cylinder pressure was 71.3 bar in the baseline test and dropped progressively to 51.6 bar when in the most significant substitution. The rate of heat release increased by about 92.5% with ethanol concerning the baseline test. When ethanol was used, the CO emissions decreased by up to 43%, resulting in about 2.4 g/kWh, while NOx emissions reduced by up to 20% compared to the baseline test, achieving 0.69 g/kWh. The economic analysis made it clear that the operational cost increased when the engine worked with ethanol replacing partially diesel fuel. However, with a slight increase in operational cost, especially in São Paulo (SP) state, it is possible to reduce pollutant emissions. For the baseline test, the operating cost was 0.354 U$/kWh. The specific fuel cost reaches a maximum of 0.441 U$/kWh, 25% higher than the respective baseline test, increasing ethanol fraction.

Biodiesel Fuel from Waste Cooking Oil: A Cheaper and Cleaner Renewable Energy Source

Low cost, high fatty acid content waste cooking oil was transformed into biodiesel using an acid catalyzed chemical esterification reaction with 0.5 vol.% of H2SO4 at 60�C for 1 hour followed by the main transesterification reaction. For the purpose of comparison, biodiesel fuel was also prepared using straight vegetable oils (SVO�s). The gas chromatography test showed higher than 95% FAME (fatty acid methyl ester) content for different types of utilized feedstocks. Biodiesel fuel and its blends were characterized based on ASTM test methods to investigate its density, viscosity, flash point, pour point, heating value, and its cetane index and similar physical properties were obtained for all the prepared biodiesel fuels. B20 blend, which contains 20 vol.% of biodiesel and 80 vol.% of diesel, showed a better performance than B0 (100 vol.% of diesel) when tested in a laboratory compression ignition diesel engine. After simulation of the production process via Aspen Hysys, a feasibility study was conducted and the results revealed that utilizing waste cooking oils (WCO�s) as feedstock is more economical than starting with SVO�s as raw material.