Nitrogen Oxide Emissions Research Articles

Short-Term Exposure to Fine Particulate Matter and Ozone: Source Impacts and Attributable Mortalities.

Short-term exposure to particles with aerodynamic diameters less than 2.5 μm (PM2.5) and ozone (O3) are important risk factors for human health. Despite the awareness of reducing attributable health burden, region-specific and source-specific strategies remain less explored due to the gap between precursor emissions and health effects. In this study, we isolate the health burden of individual sector sources of PM2.5 and O3 precursors, nitrogen oxides (NOx) and volatile organic compounds (VOCs), across the globe. Specifically, we estimate mortalities attributable to short-term exposure using machine-learning-based daily exposure estimates and quantify sectoral impacts using chemical transport model simulations. Globally, short-term exposure to PM2.5 and O3 result in 713.5 (95% Confidence Interval: 598.8-843.3) thousand and 496.3 (371.3-646.1) thousand mortalities in 2019, respectively, of which 12.5% are contributed by fuel-related NOx emissions from transportation, energy, and industry. Sectoral impacts from anthropogenic NOx and VOC emissions on health burden vary significantly among seasons and regions, requiring a target shift from transportation in winter to industry in summer for East Asia, for instance. Emission control and health management are additionally complicated by unregulated natural influences during climatic events. Fire-sourced NOx and VOC emissions, respectively, contribute to 8.5 (95% CI: 6.2-11.7) thousand and 4.8 (3.6-5.9) thousand PM2.5 and O3 mortalities, particularly for tropics with high vulnerability to climate change. Additionally, biogenic VOC emissions during heatwaves contribute to 1.8 (95% CI: 1.5-2.2) thousand O3-introduced mortalities, posing challenges in urban planning for high-income regions, where biogenic contributions to health burden during heatwaves are 13% of anthropogenic contributions annually. Our study provides important implications for temporally dynamic and sector-targeted emission control and health management strategies, which are of urgency under the projection of continuously increasing energy consumption and changing climate.

Numerical Simulation Research on Combustion and Emission Characteristics of Diesel/Ammonia Dual-Fuel Low-Speed Marine Engine

Amid increasingly stringent global environmental regulations, marine engines are undergoing an essential transition from conventional fossil fuels to alternative fuels to meet escalating regulatory requirements. This study evaluates the effects of injection pressure, the timing of ammonia injection, and the pre-injection of ammonia on combustion and emissions, aiming to identify optimal operational parameters for low-speed marine engines. A three-dimensional model of a large-bore, low-speed marine engine in a high-pressure diffusion mode was developed based on computational fluid dynamics (CFD). Simulations were conducted under 25%, 50%, 75% and 100% loads with a high ammonia energy substitution rate of 95%. The results indicate that, compared to traditional pure diesel operation, adjusting the injection pressure and the ammonia injection timing, along with employing appropriate pre-injection strategies, significantly enhances in-cylinder pressure and temperature, improves thermal efficiency, and reduces specific fuel consumption. Additionally, the dual-fuel strategy using diesel and ammonia effectively reduces nitrogen oxide emissions by up to 37.5% and carbon dioxide emissions by 93.7%.

Conjoint impact of modified HHO system, compression ratio variation, and tribological enhancement of steel piston ring substrates on performance and emission characteristics of a spark-ignition engine

In these times of efforts to develop high-efficiency hydrogen-adopted or hydrogen-fueled internal combustion engines (ICEs), and concerns related to electric vehicles such as battery cost, drawbacks in harsh winter climates, low range, etc., it is important to generate original ideas in line with the manufacturing of ICEs with improved efficacy. Accordingly, this study presents a comprehensive experimental investigation to observe the cooperated effects of pulse width modulation (PWM)-controlled hydroxy (HHO) gas introduction and improvement in tribological performance of piston ring-cylinder liner mechanism on performance and emission characteristics of a spark-ignition (SI) engine (co-system). The variation of compression ratio (CR), influence of two electrolyzer types of tube electrolyzer (TE) and plate electrolyzer (PE) for production of HHO gas, and zeta potential (ZP)-based dynamic light scattering (DLS) analysis to specify the optimal catalyst concentration in de-ionized water were also observed. Electron cyclotron resonance-chemical vapor deposition (ECR-CVD) method was utilized to bombard the piston ring substrates with diamond-like carbon (DLC) atoms under high energy plasma to improve the mechanical strength of the friction surface. Using linear tribometer, the uncoated (UPR) and coated piston rings (CPR) underwent friction tests to determine the wear rate (WR), and coefficient of friction (COF) which have substantial contribution to frictional losses. The surfaces of the samples were visualized via scanning electron microscopy (SEM) and atomic force microscopy (AFM) before and after abrasion tests to analyze carbon coating and its effects on tribological performance. The observations depicted that HHO flowrate needs to be varied as the engine load and CR change, and based on these observations, PWM control unit was designed, manufactured and reprogrammed so as to adjust electrical power consumption of HHO system when needed. The aforementioned analyses ensured optimization of the overall system so as to maximize the efficiency of the test engine. The co-system with optimized parameters (CPR + HHO + PWM) yielded an increase in average brake power (Pe) up to 31%, and average reductions in specific fuel consumption (β), carbon monoxide (CO), unburned hydrocarbon (UHC), and nitrogen oxide (NOx) emissions by 17%, 25%, 19%, and 14%, respectively at engine load range from 20% to 100%. It is expected that this study will be a good guide in terms of developing high-efficient ICEs due to promising results provided by the co-system.

Development of an ammonia decomposition reactor, afterburner and post-decomposition reactor for 1 kW solid oxide fuel cells using ammonia

Solid oxide fuel cells can overcome the poor flammability of ammonia by directly converting the chemical energy of ammonia into electricity. However, thermal stress by internal decomposition, nitriding at the solid oxide fuel cells stack and nitrogen oxides emissions must be considered when using ammonia in solid oxide fuel cells. In this study, an ammonia fuel processor was developed for stable operation and low emissions of solid oxide fuel cells using ammonia. The ammonia fuel processor consisting of an ammonia decomposition reactor, an afterburner and a post-decomposition reactor was tested using simulated off-gases of solid oxide fuel cells using ammonia. The ammonia conversion of the decomposition reactor varied from 32 % to 84 % with off-gas temperatures from 360 °C to 670 °C. When ammonia conversion after the solid oxide fuel cell stack was 99.70 %, nitrogen oxides emissions of the afterburner was 1.05 g/kWh, which is higher than the regulatory limit of 0.26 g/kWh. High fuel utilization and excess air ratio made nitrogen oxides emission even worse. The regulatory limit was successfully satisfied by using the post-decomposition reactor even when ammonia conversion after the solid oxide fuel cell stack was 99.10 %. The developed ammonia fuel processor could supply fuel at the optimal hydrogen-to-ammonia ratio and prevent nitrogen oxides emissions in solid oxide fuel cells using ammonia.

Engine Behavior Analysis on a Conventional Diesel Engine Powered with Blends of Lemon Grass Oil Biodiesel–Diesel Blends

<div>Fossil fuel usage causes environmental pollution, and fuel depletion, further affecting a country’s economy. Biofuels and diesel-blended fuels are practical alternatives to sustain fossil fuels. This experimental study analyses lemongrass oil’s performance, emissions, and combustion characteristics after blending with diesel. Lemongrass oil is mixed with diesel at 10 (B10), 15 (B15), and 25% (B25) and evaluated using a 5.20 kW direct injection diesel engine. B10 brake thermal efficiency is 36.47%, which is higher than other blends. The B10 displays an 8.73% decrease in brake-specific fuel consumption compared to diesel. An increase in exhaust gas temperature for B10 than diesel is 4.5%. It indicates that higher lemongrass oil blends decrease exhaust gas temperature. The decrease in average carbon monoxide emissions in B10 to diesel is 22.19%. The decrease in hydrocarbon emissions for B10 to diesel is 7.14%. Biodiesel with lemongrass oil increases nitrogen oxide (NOx) because of increased temperature and poor combustion. Apart from NOx emissions, all other parameters of lemongrass oil blends are suitable for practical diesel applications. The significant findings benefit the biodiesel community toward the efficient combustion of biodiesel blends.</div>

Impact of diesel/renewable fuels blend on gaseous and particle emissions of a light-duty vehicle under real driving emissions

In this study, the environmental impact of Bio-butanol (BB) and Hydrotreated Vegetable Oil (HVO) use, each blended with diesel fuel, was investigated. To this aim, pollutant emissions were measured at the exhaust of an Euro 5 commercial light-duty vehicle, fueled with diesel, BB/diesel blend (10 %v BB) and HVO/diesel blend (15 %v HVO). The experimental activity was realized by performing Real Driving Emission (RDE) tests in Napoli (Italy), which allowed to measure total hydrocarbons (THC), carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOX), and particle emissions during the real use of vehicle by using a portable emission measurement systems (PEMS). The results show that the differences between fuels are small and not statistically significant for all emission parameters. CO and THC emissions increase with the renewable fuel blends, mainly with the BB blend in the urban environment due to the increasing of cold start contribution. NOX emissions increased with BB (by approximately 4 %) and decreased with the HVO (by approximately 13 %). With both renewable fuel blends, particle emissions at engine output were reduced by 25 %–41 % and fuel consumption by 6 %–10 % compared with diesel.

Investigation of the use of aluminum oxide nanoparticle-enhanced waste cooking oil blends in compression ignition engines.

The sustainable utilization of waste cooking oil (WCO) as an alternative to fossil fuels has gained considerable attention due to its potential for delivering substantial environmental and economic benefits. This research attempts to explore the impact of incorporating aluminum oxide nanoparticles (AONP) into WCO on the emissions, combustion characteristics, and overall performance of a single-cylinder compression ignition (CI) engine. Comparative analyses were conducted against conventional commercial diesel fuel and pure WCO, as well as varying blends of WCO with AONP at 25ppm, 50ppm, and 75ppm concentrations. The experimental results demonstrate a notable enhancement in brake thermal efficiency (BTE), with a 13.2% increase observed in the WCO + 75 AONP fuel blend compared to neat WCO. Engines fueled by WCO nanoparticle blends showed significant augmentation in-cylinder pressure and heat release rates. Furthermore, these blends exhibited a substantial reduction in carbon monoxide (CO), hydrocarbons (HC), and soot emissions by 44%, 31%, and 48%, respectively, while nitrogen oxide (NO) emissions increased by 7% compared to neat WCO. Among the assessed fuel mixtures, the WCO + 75 AONP blend demonstrated higher engine performance. This study underscores the potential of aluminum oxide nanoparticle-enhanced WCO blends as viable and environmentally responsible options for sustainable energy solutions. However, challenges such as production costs and long-term fuel stability must be addressed to establish nano-fuels as financially viable alternatives.

Environmental emission characteristics of diesel engine performance using biodiesel by cotton and pumpkin seed

<p>The hunt for alternative fuels that may be utilized in place of conventional fuels is intensifying quickly since the availability of fossil fuels is dwindling daily. In this work, biodiesel derived from pumpkin and cotton seed oils is presented for use as diesel engine fuel. Related to diesel, the calorific value of this precise biodiesel is low. In a 4-stroke diesel engine, four mixes (B0, B25, B50, B75 and B100) of biodiesel were evaluated. The engine's emissions and combustion results were contrasted with the diesels. When all blended fuels are related to diesel fuel, the test repercussions illustrate a small increase in the thermal efficiency of the brakes and a decrease in the consumption of fuel specifically for the brake. Emissions of Carbon monoxide and the usage of biodiesel subsequent in a reduction in hydrocarbon emissions and an upsurge in carbon dioxide and nitrogen oxide emissions. The experiment's results showed that biodiesel, which is derived from these seed oils, maybe a useful diesel replacement for compression ignition engines.</p>

Influence of γ-Fe2O3 Nanoparticles Added to Gasoline–Bio-Oil Blends Derived from Plastic Waste on Combustion and Emissions Generated in a Gasoline Engine

The environmental pressure to reduce the use of fossil fuels such as gasoline generates the need to search for new fuels that have similar characteristics to conventional fuels. In this sense, the objective of the present study is the use of commercial gasoline in mixtures with pyrolytic oil from plastic waste and the addition of γ-Fe2O3 nanoparticles (NPs) in a spark ignition engine to analyze both the power generated in a real engine and the emissions resulting from the combustion process. The pyrolytic oil used was obtained from thermal pyrolysis at low temperatures (450 °C) of a mixture composed of 75% polystyrene (PS) and 25% polypropylene (PP), which was mixed with 87 octane commercial gasoline in 2% and 5% by volume and 40 mg of γ-Fe2O3 NPs. A standard sample was proposed, which was only gasoline, one mixture of gasoline with bio-oil, and a gasoline, bio-oil, and NPs mixture. The bio-oil produced from the pyrolysis of PS and PP enhances the octane number of the fuel and improves the engine’s power performance at low revolutions. In contrast, the addition of iron NPs significantly improves gaseous emissions with a reduction in emissions of CO (carbon monoxide), NOx (nitrogen oxide), and HCs (hydrocarbons) due to its advantages, which include its catalytic effect, presence of active oxygen, and its large surface area.

Emissions from heavy-duty diesel, natural gas, and diesel-hybrid electric vehicles – Part 1. NOx, N2O and NH3 emissions

The current study characterized nitrogen oxide (NOx), nitrous oxide (N2O), and ammonia (NH3) emissions from 14 heavy-duty vehicles from different vocations (school bus, transit bus, refuse hauler, delivery vehicle, and goods movement vehicle) over different drive cycles using a chassis dynamometer. Test vehicles with engines ranging in model year from 2009 to 2018 and including diesel and compressed natural gas (CNG) vehicles. The diesel vehicles included both vehicles without selective catalytic reduction (no-SCR) and with SCR certified to the 0.2 g per brake horsepower-hour (g/bhp-hr) [0.27 g/kilowatt-hour (kW-hr)] NOx emissions standard that were operated with diesel fuel, with a subset tested on hydrotreated vegetable oil (HVO). The CNG vehicles were all three-way catalyst (TWC) equipped and certified to either the 0.2 or 0.02 g/bhp-hr NOx standard [0.27 or 0.027 g/kW-hr]. This study is part of a larger project that included over 200 in-use heavy-duty vehicles, which is one of the most extensive studies of emissions from modern heavy-duty vehicles to date. NOx, NH3, and N2O emissions varied depending on the vocation and the technology. Average NOx emissions for the Urban Dynamometer Driving Schedule (UDDS) cycle over all vehicles ranged from 0.003 to 6.16 g/bhp-hr [0.004 to 8.25 g/kW-hr] and from 0.02 to 17.2 g/mile [0.012 to 10.7 g/km], with the diesel vehicles showing the highest emissions, the 0.2 g/bhp-hr certified CNG vehicles showing lower emissions, and the 0.02 g/bhp-hr certified CNG vehicles showing very low emissions. NOx emissions over other different cycles were generally in the same range as those for the hot start UDDS, with the highway cycles generally showing the lowest emissions. CNG vehicles had relatively high NH3 emissions ranging from 0.13 to 0.34 g/bhp-hr [0.17 to 0.46 g/kW-hr] and from 0.44 to 0.97 g/mile [0.27 to 0.6 g/km] over the hot start UDDS compared to the SCR-equipped diesel vehicles due to NH3 formation across the TWC. N2O emissions did not show consistent trends and were near/at the detection limits for a number of the vehicles.

Innovative torque-based control strategy for hydrogen internal combustion engine

Over the past years, several efforts have been made to reduce greenhouse gas emissions coming from the transport sector. Due to the highly efficient CO2-free combustion and low manufacturing costs, Hydrogen Internal Combustion engines (H2ICEs) are considered one of the most promising solutions for the future of medium and heavy duty vehicles. However, the combustion of an air-hydrogen mixture presents challenges related to the production of nitrogen oxides (NOx) and high knock tendency, mainly due to the chemical characteristics of the fuel. Although these problems can be mitigated by the use of a lean mixture, which is also useful to increase the combustion efficiency, the presence of excess air reduces exhaust temperatures and, consequently, the enthalpy content in the exhaust would be limited, leading to a reduced boosting capability. Therefore, a proper control of mixture preparation and combustion phasing is mandatory to limit NOx emissions, avoid abnormal combustions, and maximize efficiency without performance limitations.This paper focuses on the design of a dedicated control strategy for H2ICEs. Starting from a previously validated 1-D engine model operated with hydrogen, a 0-D Artificial Neural Network (ANN) - based engine model has been designed and calibrated. By using the obtained fast running ANN-based model, an innovative torque-based engine controller has been developed and both engine and controller models have been tested covering different torque profiles. The results show good accuracy within a range of ±5% on producing the requested torque by controlling the centre of combustion.

Experimental investigation of ternary blends on performance, and emission behaviors of a modified low-heat rejection CI engine

This study investigated the performance, combustion, and emissions of a modified low heat rejection (LHR) diesel engine fueled with a blend of 90 % coconut waste cooking oil (CWCO) biodiesel and 10 % diethyl ether (DEE). The engine combustion chamber components were coated with 300 μm lanthanum-doped partially stabilized zirconia for thermal insulation. Engine testing was performed at varied loads from 0 to 100 % using an eddy current dynamometer. Exhaust emissions, including hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), and smoke were measured. Compared to conventional diesel, the CWCO-DEE blend showed a 3 % higher brake thermal efficiency of 33.4 % and 2.42 % lower brake-specific fuel consumption at full load. HC, CO, and smoke emissions decreased by 18 % (39 ppm), 11 %, and 19 % at higher loads with the blend. However, NOx emissions increased slightly by 21.2 %. The DEE compensated for CWCO's lower cetane number and viscosity, while the LHR coating enhanced combustion by providing thermal insulation, raising exhaust gas temperatures by 13 %. The improved efficiency and reduced emissions demonstrate the potential of optimized biodiesel-additive blends in conjunction with LHR engine modifications to sustainably utilize inexpensive waste cooking oil feedstocks as renewable diesel replacements. However, further optimization of blend compositions, additives, and coatings is needed to balance performance benefits against possible NOx increases. This study highlights a promising combined approach leveraging engine design and fuel advancements.

Effect of Partial Substitution of Chemical Fertilizers with Organic Fertilizers on N2O and NO Emissions from a Peach Orchard

Organic fertilizer substitution has been promoted as a weight loss, efficient, and diversified fertilizer substitution technology in agricultural production. However, there is a lack of comprehensive assessment of the impact of organic fertilizers on N2O and NO emissions from orchards. In this study, N2O and NO emissions from peach orchards were observed annually using static dark box-gas chromatography to compare the effects of chemical fertilizer application alone and partial replacement of chemical fertilizer treatment on NO emissions from peach orchards. The results showed that the partial replacement of chemical fertilizers with organic fertilizers reduced the total N2O and NO emissions from peach orchards by 15.0 % and 9.4 %, respectively. The N2O and NO emission factors were reduced by 21.3 % and 21.1 %. The mineral N content of the soil in the organic fertilizer treatment was lower than that in the chemical fertilizer treatment alone. The organic fertilizer treatment increased the contribution of AOA to nitrification and decreased the contribution of AOB, thus reducing N2O and NO from nitrification. In addition, the results of the dual isotope mixing model[δ18O(N2O/H2O) vs. δ15NSP] indicated that the bacterial denitrification/nitrifying bacterial denitrification (bD/nD) process served as the primary pathway for N2O emissions in peach orchards. Partial substitution with organic fertilizers enhanced soil denitrification, resulting in larger reductions in the amounts of N2O and NO. Therefore, partial substitution of organic fertilizer is a viable measure to mitigate nitrogen oxide emissions from orchards and to achieve green and low-carbon development in agriculture.

Impact of injection pressure on the performance, emissions, and combustion of a common rail direct injection engine fueled with quaternary blends

The scarcity and rising costs of fossil fuels, coupled with increasing pollution levels, have prompted the exploration of innovative biofuel blends. While binary and ternary fuels have been studied extensively in proportions of 5–20%, replacing up to 30–40% of fossil fuel dependency without significant engine modifications remains a challenge. One potential solution is to investigate an optimal quaternary blend (QB) through experimental methods. This study investigates the impact of increased injection pressure (IOP) and quaternary fuel blends on a common rail direct injection (CRDI) engine's performance and emissions. Different blends, including diesel fuel, vegetable oil, mahua methyl ester and normal-butanol, were tested to replace 30–40% of diesel and enhance combustion, reduce exhaust emissions and improve overall performance. Experiments used a 1-cylinder CRDI engine at high IOPs (400, 500, 600 and 700 bar). Results at 600 bar IOP showed that the optimal blend, QB3–QB4, increased brake thermal efficiency (BTE) by 9% and reduced brake-specific fuel consumption (BSFC) by approximately 11% compared to other blends. Emissions at 600 bar included a 16% reduction in hydrocarbons (HC) and a 24% decrease in carbon monoxide (CO) at full load. However, nitrogen oxide (NOx) emissions slightly increased with higher IOP. Significantly employing the QB3–QB4 blend at 600 bar improved control over HC, CO and smoke emissions. Overall, performance was enhanced and comparable to conventional diesel fuel, with only a minor increase in NOx emissions.

Comparative thermal assessment and emission analysis of various green biodiesel from novel feedstocks for CI engines: a sustainable approach towards emission reduction.

In order to replace conventional diesel, biodiesel from various feedstocks is being researched for diesel engines. This study explores novel biodiesel blends produced from unconventional resources such as mentha piperita (peppermint), pontederia crassipes (water hyacinth), tamarindus indica (tamarind), and trichosanthes cucumerina (snake gourd) to assess the outcomes of a diesel engine. The fuel samples are designated as MP20, PC20, TC20, and TI20, which consist of 80% biodiesel and 20% diesel. The assessment is carried out on a four-stroke, one-cylinder diesel engine that is water-cooled and set to operate at 1500rpm with a 17.5 compression ratio under various engine loading scenarios with quarter-incremental loading from one-fourth to full loading conditions. The fuel samples are injected with 220bar injection pressure into the combustion chamber 23° before TDC. An extensive analysis of engine parameters is performed using engine configuration, fuel characteristics, and applied boundary conditions. This comprises brake-specific energy consumption (BSEC), fuel consumption (BSFC), thermal efficiency (BTE), cylinder pressure (CP), heat release rate (HRR), particulate matter (PM), nitrogen oxide (NOx), and carbon dioxide (CO2) emissions. At 100% load, the biodiesel blends show an increase in BSFC (2.8-12.6%) and BSEC (1.1-7.1%) but a minor decrease in CP (0.9-6.9%), HRR (0.8-16.2%), and BTE (1.2-2.9%). For biodiesel blends at full engine load, the emissions of PM (8.9-21.4%), NOx (1.4-16.2%) and CO2 (2.4-7.9%) are all significantly reduced. The results emphasize the distinct benefits of biodiesel blends, demonstrating enhanced engine performance and substantial decreases in emissions, which supports the aim of providing sustainable energy solutions.

Development of the two-stage SCR control strategy to satisfy ultra-low NOX emission regulation for heavy-duty diesel engine

The emission regulations for heavy-duty diesel engines regarding nitrogen oxide (NOX) are becoming increasingly stringent, particularly in relation to cold start cycles. While the two-stage selective catalytic reduction (SCR) has the potential to achieve ultra-low NOX emissions, several challenges remain, including the accurate prediction of ammonia (NH3) storage mass and the co-control of the two-stage SCR. The first step in this study involved the establishment of a rapid control prototype platform to facilitate the development and validation of a two-stage SCR control strategy. Secondly, an initial method for predicting the NH3 storage based on the mass conservation law was proposed, which was subsequently improved by filling and emptying experiments. The third step involved the development of a two-stage SCR co-control strategy, including obtaining the steady-state NH3 storage target value, dynamic correction for NH3 storage target value, regulation of NH3 storage, and control of the close-coupled SCR urea injector state. Finally, the two-stage SCR urea injection control strategy was certified under the world harmonized transient cycle (WHTC). The results demonstrate that the composite value of engine outlet NOX emissions under cold and hot start WHTC cycles is 13 g/(kW·h). Meanwhile, the composite value of tailpipe NOX emissions under cold and hot start WHTC cycles is 0.065 g/(kW·h), representing only 14% of the EU VI limit value of 0.46 g/(kW·h). Thus, the findings demonstrate that integrating an accurate NH3 storage prediction method with the two-stage SCR co-control function is crucial for heavy-duty diesel engines to achieve ultra-low NOX emissions.

Synergistic effect of hydrogen induction on the performance, combustion and emission phenomenon of dual-fuel CI engine with Chlorella vulgaris algae oil and its methyl ester

The present work aims to investigate the cumulative effect of hydrogen enrichment with the fuels of diesel, Neat chlorella vulgaris oil (NCVO), and Chlorella vulgaris methyl ester (CVME) in a mono-cylinder CI engine. The performance, combustion, and emission parameters of diesel, NCVO, and CVME are analyzed and compared to the findings obtained with hydrogen induction in the intake manifold under dual fuel configuration. With the effect of hydrogen infusion, the metrics of performance, combustion and emission parameters are improved. Under maximum load condition, the induction of hydrogen escalates the BTE from 32.74%, 28.01%, and 23.02%–35.39%, 31.40%, and 28.12% with diesel, CVME, and NCVO at maximal hydrogen share energy of 14.38%, 11.50% and 9.61% respectively. Alongside, the enrichment of hydrogen declines the carbon monoxide (CO) from 4.13, 10.38, and 19.24 g/kWh to 3.16, 8.02, and 15.26 g/kWh, unburned hydrocarbons (UHC) from 0.51, 0.71, and 2.02 g/kWh to 0.36, 0.50, and 1.64 g/kWh, smoke opacity from 55%, 75%, and 85%–43%, 67%, and 71% with diesel, CVME, and NCVO respectively. However, the hydrogen's significant flame velocity and immense calorific value confect to an elevated combustion temperature and subsequent rise in heat release rate (HRR) to, cylinder pressure, and emission of nitrogen oxide (NO). Among the tested fuels, diesel posses maximum HRR and cylinder pressure of 80.46 J/0CA and 88.67 bar respectively. Maximum specific NO emission was observed with CVME having 10.80 g/kWh, whereas diesel and NCVO has 9.49 g/kWh and 4.93 g/kWh respectively.

Impact of Using n-Octanol/Diesel Blends on the Performance and Emissions of a Direct-Injection Diesel Engine

This study evaluates the viability of n-octanol as an alternative fuel in a direct-injection diesel engine, aiming to enhance sustainability and efficiency. Experiments fueled by different blends of n-octanol with pure diesel were conducted to analyze their impacts on engine performance and emissions. The methodology involved testing each blend in a single-cylinder engine, measuring engine performance parameters such as brake torque and brake power under full-load conditions across a range of engine speeds. Comparative assessments of performance and emission characteristics at a constant engine speed were also conducted with varying loads. The results indicated that while n-octanol blends consistently improved brake thermal efficiency, they also increased brake-specific fuel consumption due to the lower energy content of n-octanol. Consequently, while all n-octanol blends reduced nitrogen oxide emissions compared to pure diesel, they also significantly decreased carbon monoxide, hydrocarbons, and smoke opacity, presenting a comprehensive reduction in harmful emissions. However, the benefits came with complex trade-offs: notably, higher concentrations of n-octanol led to a relative increase in nitrogen oxide emissions as the n-octanol ratio increased. The study concludes that n-octanol significantly improves engine efficiency and reduces diesel dependence, but optimizing the blend ratio is crucial to balance performance improvements with comprehensive emission reductions.

Comparative analysis of energy, exergy, emission, and sustainability aspects of third generation microalgae biodiesels in a diesel engine

Third-generation biodiesel produced from various microalgae species is being researched for its production, conversion, compatibility, sustainability, and environment-friendly behaviour for the diesel engine as a replacement of conventional diesel fuel. The present work is conducted with the objective of analysing a clean, green, and sustainable microalgae biodiesel for energy, exergy, emission, and sustainability assessment in a diesel engine system, along with the evaluation of air quality in terms of emission analysis for assessing its impact on climate. The fuel samples from diesel and the three microalgae species, viz., Chlorella emersonii, Euglena sanguinea, and Spirulina, are designated as DF100, CE100, ES100, and SP100, respectively. The engine behaviour is assessed and compared at 1500 rpm under 17.5 compression ratio with 25–100 % engine load. DF100 achieves the maximum energy and energy efficiency of 32.76 % and 30.74 %, respectively, and a varied range of 27.32–30.37 % and 25.28–28.10 % with microalgae biodiesels. The air quality is improved with the reduction of PM emissions by 15.82–27.09 % at the cost of improved nitrogen oxide (NOx) emissions by 11.03–15.55 %. The sustainability index is highest for DF100 (1.247–1.444), and among biodiesel fuel samples, it is highest for SP100 (1.233–1.391) at all engine loads. These results point to the possibility of microalgae-derived biodiesel blends as feasible diesel fuel substitutes, providing environmentally friendly and effective solutions for internal combustion engines.

Experimental Research on Regulated and Unregulated Emissions from E20-Fuelled Vehicles and Hybrid Electric Vehicles

Ethanol as a renewable fuel has been applied in fuel vehicles (FVs), and it is promising in hybrid electric vehicles (HEVs). This work aims to investigate the emission characteristics of ethanol applied in both FVs and plug-in hybrid electric vehicles (PHEVs). The paper conducted a real-road test of an internal combustion FV and PHEV, respectively, based on the world light vehicle test cycle (WLTC) by using gasoline and regular gasoline under different temperature conditions. The use of E10 and E20 in FVs has been effective in reducing the conventional emissions of the vehicles. At 23 °C, E10 and E20 reduced the conventional emissions including carbon monoxide (CO), total hydrocarbon compound (THC), non-methane hydrocarbon compound (NMHC), particulate matter (PM), and particulate number (PN) by 15.40–31.11% and 11.00–44.13% respectively. At 6 °C, E10 and E20 reduced conventional emissions including THC, CO, and PM by 2.15–8.61% and 11.02–13.34%, respectively. However, nitrogen oxide (NOX) emissions increased to varying degrees. The reduction trend of non-conventional emissions including methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) from FVs fueled with E10 and E20 is not significant for vehicles. Overall, the emission reduction effect of E20 is better than that of E10, and the emission reduction effect of ethanol gasoline on vehicle emissions is reduced at low temperatures. Lower ambient temperatures increase vehicle emissions in the low-speed segment but decrease vehicle emissions in the ultra-high-speed segment. HEV emissions of THC, CO, PN, and PM are reduced by 25.28%, 12.72%, 77.34%, and 64.59%, respectively, for E20 compared to gasoline, and the use of E20 in HEVs contributes to the reduction of overall vehicle emissions.