Nitrogen Oxide Emissions Research Articles

Analyzing the influence of feedstock selection in pyrolysis on aviation gas turbine engines: A study on performance, combustion efficiency, and emission profiles

Commercial aviation is primarily reliant on fossil fuels, yet the depletion of these sources and the consequences of climate change necessitates the exploration of sustainable alternatives. The pyrolysis process offers a viable method for producing biofuels from various feedstocks. This research examines the combustion, emission, and performance characteristics of biofuels derived from agricultural residues, waste tyres, and plastics using pyrolysis. Pyrolysis oils derived from forestry or agricultural products exhibit high viscosity and moisture content, which impairs combustion efficiency and increases carbon monoxide (CO) from 70 % to 187 % and unburned hydrocarbon (UHC) emissions. Conversely, pyrolysis oils from plastics and waste tyres provide stable combustion with carbon monoxide and total hydrocarbon emissions (THC) comparable to those of commercial jet fuel. However, nitrogen oxide (NOX) emissions are significantly elevated from 57 % to 157 %. Engine performance tests demonstrated that forestry pyrolysis oils result in thrust loss due to their high viscosity value (14.3–113 mm2/s) and low calorific value (17.3–31.7 MJ/kg). In contrast, plastic and tyre pyrolysis oil perform similarly to commercial jet fuels but may potentially cause performance loss due to their high aromatic content (>47.67 %). Overall, upgrading the viscosity, moisture, and aromatic content of pyrolysis oils can enhance their suitability as alternative aviation fuels. These improvements could assist the aviation sector in achieving its carbon-neutral goals by making pyrolysis oils competitive with conventional jet fuels.

Comparative analysis of real-world vehicular emissions from BS-IV and BS-VI cars in India.

This study investigates real-world carbon dioxides (CO2) and nitrogen oxides (NOx) emissions from diesel (Bharat Stage-IV (BS-IV)) and petrol/gasoline (BS-IV and BS-VI) cars in Indian driving conditions using a portable emission measurement system (PEMS). The paired sample t-test revealed a significant difference ( < 0.05) in NOx and CO2 emissions among the three types of cars, except for CO2 emissions ( > 0.05) between BS-IV petrol and BS-VI petrol cars. The highest NOx emission rates were observed in all car types during acceleration (> 1m/s2) and deceleration (- 2m/s2). CO2 emission rates were also high during acceleration (> 1m/s2) for all car types. At low speeds (around 20 kmph), all car types had low emissions of CO2 and NOx, with acceleration and deceleration rates ranging from - 0.5 to 0.5m/s2. BS-IV diesel cars emit significantly higher NOx emissions compared to petrol cars, especially at vehicle-specific power (VSP) bin 0 (deceleration to idling mode) and during VSP bin 7 (acceleration mode). BS-IV diesel cars emit 228% and 530% higher NOx emissions than BS-IV and BS-VI petrol cars at VSP bins 0 and 7, respectively. CO2 emissions from BS-VI petrol cars were 10% lower than those from BS-IV petrol cars across all VSP bins, indicating moderate reductions. Furthermore, diesel cars emit 140% less CO2 emissions than petrol cars across various VSP bins. The findings highlight the need for cleaner technologies and responsible driving practices to address vehicular emission concerns.

Mutagenicity evaluation of methyl tertiary- butyl ether in multiple tissues of transgenic rats following whole body inhalation exposure.

Methyl tertiary-butyl ether (MTBE) is used as a component of motor vehicle fuel to enhance combustion efficiency and to reduce emissions of carbon monoxide and nitrogen oxides. Although MTBE was largely negative in the in vitro and in vivo genotoxicity studies, isolated reports of positive findings along with the observation of tumors in the rat cancer bioassays raised concern for its in vivo mutagenic potential. To investigate this, transgenic male Big Blue Fischer 344 rats were exposed to 0 (negative control), 400, 1000, and 3000 ppm MTBE via whole body inhalation for 28 consecutive days, 6 h/day. Mutant frequencies (MF) at the cII locus of the transgene in the nasal epithelium (portal of entry tissue), liver (site of primary metabolism), bone marrow (rapidly proliferating tissue), and kidney (tumor target) were analyzed (5 rats/exposure group) following a 3-day post-exposure manifestation period. MTBE did not induce a mutagenic response in any of the tissues investigated. The adequacy of the experimental conditions to detect induced mutations was confirmed by utilizing tissue samples from animals treated with the known mutagen ethyl nitrosourea. These data provide support to the conclusion that MTBE is not an in vivo mutagen and male rat kidney tumors are not likely the result of a mutagenic mode of action.

Characterization of on-road nitrogen oxides and black carbon emissions from high emitters of heavy-duty diesel vehicles in China

Heavy-duty diesel vehicles (HDDVs) significantly contribute to atmospheric nitrogen oxides (NOX) and black carbon (BC), with high emitters within the HDDV fleet impacting the total emissions. However, emission patterns and contributions of high emitters are rarely explored from a fleet-perspective. We investigated NOX and BC emission factors (EFs) from 1925 HDDVs in Shenzhen by the plume-chasing method, and found that the fleet-average EFs decreased with stricter emission standards. Unexpectedly, the average NOX EF for the China IV fleet was comparable with that for the China III fleet due to possible ineffective aftertreatment in high-emitter sectors of China IV HDDVs. Decreasing trend in average NOX EF since 2017 reflected the effective emission controls by the implementation of China V standard. Besides, semi-trailer tractors exhibited a higher incidence of NOX over-emissions, whereas BC high emitters were more pronounced in box trucks. Total NOX and BC emissions from HDDVs in Shenzhen were revisited, reaching 54.0 and 1.1 Gg·yr−1, with updated NOX EF correcting a 26.2 % underestimation in national guidelines. Notably, eliminating high emitters yields greater emission reduction benefits than merely retiring old HDDVs, with BC reduction outpacing NOX. This study provides new insights into the implementation of targeted emission reduction measures for HDDVs.

Preparation and NOx Reduction Performance of Ag-Ni-TiO2/Cordierite Catalyst for HC-SCR System

Selective catalytic reduction (SCR) technology in diesel engines is an exhaust after treatment system used for abatement of nitrogen oxide (NOx) emissions. In order to synthesize Ag-Ni-TiO2/Cordierite catalyst in the conducted study, a solution including silver nitrate (AgNO3), titanium dioxide (TiO2), and nickel (II) nitrate hexahydrate (Ni(NO3)2·6H2O) were used in the coating of the cordierite (2Al2O3-5SiO2-2MgO) main carrier structure. The prepared catalyst was characterized for morphological characteristics via scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analysis. The NOx reduction measurements as catalytic was carried out at 20 °C intervals in the temperature range from 190 to 270°C at 1 kW and 3 kW motor loads and under 30000 h−1 space velocity (SV). Ethanol was used as a reductant during the experiments. As a results of the measurements, it was seen that the Ag-Ni-TiO2/Cordierite catalyst exhibited a good NOx conversion efficiency with 93.8 % at 270°C at 3 kW.

Characterizing multi-pollutant emission impacts of sulfur reduction strategies from coal power plants

Fuel combustion for electricity generation emits a mix of health- and climate-relevant air emissions, with the potential for technology or fuel switching to impact multiple emissions together. While there has been extensive research on the co-benefits of climate policies on air quality improvements, few studies have quantified the effect of air pollution controls on carbon emissions. Here we evaluate three multi-pollutant emission reduction strategies, focused on sulfur dioxide (SO2) controls in the electricity sector. Traditional ‘add-on’ pollution controls like flue gas desulfurization (FGD) reduce SO2 emissions from coal combustion but increase emissions of nitrogen oxides (NO X ), volatile organic compounds (VOCs), fine particulate matter (PM2.5), and carbon dioxide (CO2) due to heat efficiency loss. Fuel switching from coal to natural gas and renewables potentially reduces all pollutants. We identified 135 electricity generation units (EGUs) without SO2 controls in the contiguous US in 2017 and quantified the unit-level emission changes using pollution control efficiencies, emission rates, fuel heat input, and electricity load. A cost-benefit analysis is conducted, considering pollution control costs, fuel costs, capital and operation and maintenance (O&M) costs, the monetized health benefits from avoided multi-pollutant, and the social cost of carbon as the benefit for carbon reduction. We find that add-on SO2 controls result in an average annual net benefit of $179.3 million (95% CI: $137.5-$221.0 million) per EGU, fuel switching from coal to natural gas, $432.7 million (95% CI: $366.4-$498.9 million) per EGU; and fuel switching from coal to renewable energy sources, $537.9 million (95% CI: $457.1-$618.9 million) per EGU. Our results highlight multi-pollutant emission reduction strategy as a cost-effective way to synergistically control air pollution and mitigate climate change.

INVESTIGATION OF THE EFFECTS OF THE DIFFERENT BIODIESELS’ BLENDS ON ENGINE PERFORMANCE

Internal combustion (IC) compression ignition (CI) engines running on diesel, play a dominant role of today’s economies, particularly in the agriculture and transport sectors. However, because of diesel associated concerns greenhouse gases (GHG) emissions, coupled with depletion of its reserves together and fluctuations in prices, the biodiesel has gained popularity as a promising alternative fuel. Unfortunately, engines running on biodiesel are associated with decreased power output, poor fuel atomization and increased nitrogen oxides emissions. Biodiesels have been blended with diesel to improve on its properties, however, it has been a difficult to obtain the best blending level, since they are sourced from a variety of vegetable oils whose fuel parameters and interactions differ considerably, causing variation in their combustion processes. Thus, the research aimed to investigate the effects of biodiesels’ blends with diesel on engine performance parameters. Five biodiesels from waste vegetable oil, canola, sunflower, oleander, and coconut oil were characterized and blended with diesel at 10, 15, 20, 25 and 30% by volume. The blends were tested in a 3.5 kW CI engine at maximum speeds and loads. Experiments indicated the biodiesel blends lead to reduced lower heating value, increased density and kinematic viscosity compared to diesel. The blends resulted into increased fuel consumption and nitrogen oxides, while, reducing on brake thermal efficiency and carbon monoxide emissions.

Aggravated surface O3 pollution primarily driven by meteorological variations in China during the 2020 COVID-19 pandemic lockdown period

Abstract. Due to the lockdown during the COVID-19 pandemic in China from late January to early April in 2020, a significant reduction in primary air pollutants, as compared to the same time period in 2019, has been identified by satellite and ground observations. However, this reduction is in contrast with the increase of surface ozone (O3) concentration in many parts of China during the same period from 2019 to 2020. The reasons for this contrast are studied here from two perspectives: emission changes and inter-annual meteorological variations. Based on top-down constraints of nitrogen oxide (NOx) emissions from TROPOMI measurements and GEOS-Chem model simulations, our analysis reveals that NOx and volatile organic compound (VOC) emission reductions as well as meteorological variations lead to 8 %, −3 % and 1 % changes in O3 over North China, respectively. In South China, however, we find that meteorological variations cause ∼ 30 % increases in O3, which is much larger than −1 % and 2 % changes due to VOC and NOx emission reductions, respectively, and the overall O3 increase in the simulations is consistent with the surface observations. The higher temperature associated with the increase in solar radiation and the decreased relative humidity are the main reasons that led to the surface O3 increase in South China. Collectively, inter-annual meteorological variations had a larger impact than emission reductions on the aggravated surface O3 pollution in China during the lockdown period of the COVID-19 pandemic.

Analysis of secondary inorganic aerosols over the greater Athens area using the EPISODE–CityChem source dispersion and photochemistry model

Abstract. Secondary inorganic aerosols (SIAs) are major components of fine particulate matter (PM2.5), having substantial implications for climate and air quality in an urban environment. In this study, a state-of-the-art thermodynamic model has been coupled to the source dispersion and photochemistry city-scale chemistry transport model EPISODE–CityChem, which is able to simulate pollutants at a horizontal resolution of 100 m×100 m, to determine the equilibrium between the inorganic gas and aerosol phases over the greater Athens area, Greece, for the year 2019. In agreement with in situ observations, sulfate (SO42-) is calculated to have the highest annual mean surface concentration (2.15 ± 0.88 µg m−3) among SIAs in the model domain, followed by ammonium (NH4+; 0.58 ± 0.14 µg m−3) and fine nitrate (NO3-; 0.24 ± 0.22 µg m−3). Simulations denote that NO3- formation strongly depends on the local nitrogen oxide emissions, along with the ambient temperature, the relative humidity, and the photochemical activity. Additionally, we show that anthropogenic combustion sources may have an important impact on the NO3- formation in an urban area. During the cold period, the combined effect of decreased temperature in the presence of non-sea-salt potassium favors the partitioning of HNO3 in the aerosol phase in the model, raising the NO3- formation in the area. Overall, this work highlights the significance of atmospheric composition and the local meteorological conditions for the equilibrium distribution of nitrogen-containing semi-volatile compounds and the acidity of inorganic aerosols, especially in urban areas where atmospheric trace elements from natural and anthropogenic sources coexist.

The impact of scavenging air state on the combustion and emission performance of marine two-stroke dual-fuel engine

The scavenging process significantly affects the combustion and emission performance of marine low-speed two-stroke dual-fuel engines. Optimizing scavenging air pressure and temperature can enhance the engine's combustion efficiency and emission control performance, thereby achieving more environmentally friendly and efficient operation of dual-fuel engines. This study focuses on marine low-speed two-stroke dual-fuel engines, analyzing the effects of scavenging air pressure (3.0 bar, 3.25 bar, 3.5 bar, and 3.75 bar) and scavenging air temperature (293 K, 303 K, and 313 K) on engine performance and emission products. The results indicate that scavenging air pressure has a greater impact on engine performance than scavenging air temperature. An increase in scavenging air pressure leads to higher thermal efficiency and power. As the scavenging air pressure increases from 3 to 3.75 bar, the indicated thermal efficiency (ITE) increases from 44.02 to 53.26%, and indicated mean effective pressure (IMEP) increases by approximately 0.35 MPa. Increased scavenging air pressure improves nitrogen oxide (NOx) and hydrocarbons (HC) emissions. For every 0.25 bar increase in scavenging air pressure, NOx emissions decrease by 3.53%, HC emissions decrease by 33.35%, while carbon dioxide (CO2) emissions increase by 0.71%. An increase in scavenging air temperature leads to lower ITE and IMEP. As the air temperature changes from 293 to 313 K, the ITE decreases by approximately 1%, and IMEP decreases by about 0.04 MPa. Increased scavenging air temperature improves CO2 emissions. For every 10 K increase in the air temperature, the CO2 emissions decrease by 0.02%, while NOx emissions increase by 4.84%, HC emissions increase by 34.39%. Therefore, controlling scavenging air pressure is more important than scavenging air temperature in the operational management of marine two-stroke engines. Higher power and lower NOx and HC emissions can be achieved by increasing the scavenging air pressure.

Evaluation of NOx and PN Emission in Relation to Actuator Control.

This study aimed to investigate the interrelationships between key harmful emission components, nitrogen oxides (NOx), and particulate numbers (PNs) in diesel engine exhaust and the control actuators of diesel engines. This research involved conducting a series of experiments under fixed parameters within an engine brake laboratory environment to elucidate these correlations. The objectives of this study were to conduct a comprehensive review of the relevant emissions technology literature and a comparative assessment of particle measurement methods based on dilution ratios and develop innovative aerosol preparation principles tailored to condensation particle measurement. Additionally, this research involved designing and implementing an aerosol preparation unit based on the newly developed principles, along with the creation of test cell control programs using the AVL PUMA Open TST editor interface and Visual Basic. Furthermore, this study was concerned with conducting evaluations of fixed-parameter engine dynamometer tests to explore the functional relationships between the emission of 10/23 nm particles, NOx emissions, common rail pressure variations, and exhaust gas recirculation levels. This study aimed to enhance the understanding of diesel engine emissions dynamics and contribute valuable insights for developing more efficient and environmentally friendly engine control strategies.

Biodiesel Sustainability: Review of Progress and Challenges of Biodiesel as Sustainable Biofuel

Biodiesel, an environmentally degradable and renewable biofuel derived from organic matter, has exhibited its capacity as a viable and sustainable substitute for traditional diesel fuel. Numerous comprehensive investigations have been conducted to assess the effects of biodiesel on internal combustion engines (ICEs), with particular emphasis on diesel engine performance metrics, combustion dynamics, and emission profiles. Biodiesel demonstrates a significant decrease in emissions of particulate matter (PM), hydrocarbon (HC), and carbon monoxide (CO) in diesel engines. The addition of biodiesel has shown a minor decrease in power output and a slight increase in fuel consumption and nitrogen oxide (NOx) emissions. Nevertheless, the extensive implementation of biodiesel, despite its potential to effectively reduce detrimental emissions, has encountered obstacles stemming from external influences including restricted availability of feedstock, volatile petroleum oil prices, and inadequate governmental backing. This review presents a concise summary of significant advancements in the global adoption of biodiesel from a sustainability perspective. This review provides valuable insights into the challenges and opportunities associated with the advancement of sustainable biofuel technologies by synthesizing the current state of palm biodiesel and examining global trends in biodiesel implementation. The wider adoption of biodiesel can be facilitated by addressing concerns pertaining to feedstock availability, price stability, and policy support. This would allow for the realization of significant environmental advantages and contribute to a more environmentally friendly and sustainable biofuel.

Numerical investigation of combustion characteristics of extended coherent flame model 3 zones (ECFM‐3Z) in diesel engines running with biodiesel

AbstractThis research investigates the application of Extended Coherent Flame Model‐3 Zones (ECFM‐3Z) to assess the performance and emissions of rapeseed oil methyl ester (ROME). Experimental tests were carried out using a Lombardini 3 LD 350 model single‐cylinder diesel engine, at 1600–3000 rpm with 200 rpm speed increments, under full load conditions. For numerical analysis, STAR‐CD/ESICE software was employed. Methyl Oleate (C19H36O2) was predicted as the surrogate biodiesel based on Gas Chromatography (GC) analysis and average mass calculation. Notably, the numerical analysis revealed a remarkable similarity in brake power between the experimental and computational investigations. In the range of 2400–3000 rpm, the biodiesel's performance exhibited a maximum deviation of 5%, primarily attributed to pumping, thermal, and friction losses. In terms of emissions, carbon dioxide (CO2) emissions were consistent with the findings of the experimental study, with a maximum disparity of 10%. However, carbon monoxide (CO) emissions ranged from 57% to 65% lower than those observed in the experimental study, while nitrogen oxide (NOx) emissions exhibited a reduction of 63% to 84%. In contrast, oxygen (O2) emissions were notably higher, ranging from 93% to 117% compared to the experimental study, and exhaust temperatures were elevated by 33% to 49% in comparison to the experimental results.

NO Formation in Combustion Engines Fuelled by Mixtures of Hydrogen and Methane

The present work addresses the production of nitrogen oxides in ICEs burning hydrogen mixed with methane. A mathematical model that allows the calculation of nitrogen oxide emissions from such combustion was built; this model uses the extended chemical kinetic mechanism of Zeldovich. Numerical simulations were carried out on the production of NO, varying the following variables: proportion of H2 to CH4, the equivalence ratio of the reactant mixture, the compression ratio, and the engine speed. The essential purpose was to assess how NO production is affected by the mentioned variables. The main assumptions were (i) Otto cycle; (ii) instantaneous combustion; (iii) chemical equilibrium reached just at the end of combustion; (iv) the formation of NO only during the expansion stroke of pistons. Results were obtained for various proportions of hydrogen and methane, various equivalence ratios, speeds of rotation, and compression ratios of an engine. In short, the results obtained in the current work show that the lowering of the equivalence ratio leads to a lower concentration of NO; that increasing the compression ratio also lowers the concentration of NO; that NO production occurs until shortly after the beginning of the expansion stroke; and finally, that the NO concentration in the engine exhaust is not very sensitive to the H2/CH4 ratio in the fuel mixture.

Achieving High Dispersion of Pd in Small-Pore Zeolite SSZ-13: A High-Efficiency Low-Temperature NOx Adsorber.

Passive NO x adsorber (PNA) materials are primarily considered for reducing nitrogen oxide emissions during the low-temperature cold start of a motor vehicle. Pd/SSZ-13 has attracted considerable attention because of its outstanding hydrothermal stability and sulfur resistance. Optimizing the dispersion of precious metal Pd in Pd/SSZ-13 is crucial for enhancing PNA performance and nitrogen oxide adsorption capability. In this study, we prepared Pd/SSZ-13 using different methods and evaluated their influence on the NO x adsorption capability. The characterization results show that the dispersion of precious metal Pd in the Pd/SSZ-13 catalyst prepared by the quantitative ion-exchange method is as high as 92.13%, and the loading amount is as high as 98.93%. Pd predominantly exists as Pd2+, achieving near-total loading and further improving the catalyst's NO x adsorption capacity. This study offers innovative approaches and methods for applying Pd/SSZ-13 as a PNA material, serving as a reference for its further optimization and performance enhancement. Continued research into the preparation and adsorption performance of Pd/SSZ-13 materials could offer solutions to reduce motor vehicle nitrogen oxide emissions.

Optimization of Performance, Emissions, and Vibration in a Hydrogen-Diesel Dual-Fuel Engine Using Response Surface Methodology

Background: Dual-fuel diesel engines using hydrogen as a secondary fuel source are a promising technology for reducing emissions while maintaining engine performance. However, optimizing these engines for all three aspects (performance, emissions, and vibration) simultaneously presents a challenge. Objective: This study aimed to address this challenge by employing Response Surface Methodology, a statistical technique used to optimize multi-variable processes. The goal was to find the ideal combination of engine load, hydrogen flow rate, and compression ratio that would maximize Brake Thermal Efficiency while minimizing Brake-Specific Fuel Consumption, Nitrogen Oxide emissions, and engine vibration. Method: A Box-Behnken design, a specific type of design optimization with three factors and three levels, was employed. The experiment evaluated the impact of three key factors: engine load (ranging from 0 - 12 kg), hydrogen flow rate (0-15 L/min), and compression ratio (16 to 18:1). The effects of these factors on performance, emissions, and vibration were measured. Results: The results revealed a trade-off between achieving optimal performance and minimizing emissions. The highest Brake Thermal Efficiency and lowest Brake-Specific Fuel Consumption were achieved at a high compression ratio (18:1), maximum hydrogen flow rate (15 L/min), and under full engine load (12 kg), corresponding to a brake power of 3.5 kW. However, these conditions also resulted in higher NOx emissions and vibration levels. Conversely, minimizing NOx and vibration occurred at a lower compression ratio (16:1), with the same maximum hydrogen flow rate (15 L/min), but at a significantly reduced engine load (3 kg), resulting in a much lower brake power of 0.875 kW. Conclusion: These findings highlight the complex relationship between performance, emissions, and vibration in a hydrogen-diesel dual-fuel engine optimized using Response Surface Methodology. While optimal conditions were identified for specific goals, achieving all desired characteristics simultaneously across the entire operating range remains a challenge.

Remarkable improvement in photocatalytic activity of g-C3N4 for NO oxidation through surface hydroxylation

The nitrogen oxide emissions originating from combustion pose significant risks to the environment. Photocatalysis is considered an efficient and environmentally friendly strategy to alleviate this problem. Graphitic carbon nitride (g-C3N4) is regarded as one of the most promising organic photocatalytic materials for environmental purification. However, its small specific surface area, weak adsorption and high recombination rate of charge carriers result in low intrinsic photocatalytic activity. To overcome these obstacles, a hydrothermal treatment of dicyandiamide-derived g-C3N4 (DCN) at different temperatures (140–200 °C) was employed to enhance the photocatalytic activity for NO oxidation. The experimental results demonstrated a significant improvement in the photocatalytic oxidation removal rate of NO after a hydrothermal treatment. The optimal photocatalyst, DCN-180, treated at 180 °C, demonstrated the highest NO removal efficiency (65.0 %), which is twice the value of pristine DCN (32.5 %). Additionally, the formation of the toxic intermediate NO2 was effectively suppressed during the reaction. Photoelectrochemical tests revealed that DCN-180 exhibited higher photocurrent density and smaller impedance radius compared to the untreated g-C3N4 sample. Moreover, density functional theory (DFT) calculations confirmed that the DCN-180 sample showed a stronger ability to adsorb O2 and NO. The enhanced photocatalytic NO oxidation performance of DCN-180 has been primarily attributed to its enlarged specific surface area (from 10.7 to 35.5 m2 g−1), local polarization effect, reduced interfacial charge transfer resistance, and improved adsorption abilities for NO and O2 molecules. This study provides valuable insights for designing and preparing highly efficient g-C3N4 based photocatalysts through surface modification for photocatalytic NO purification.

Control strategies for mode switching of a large marine two-stroke engine equipped with exhaust gas recirculation and turbocharger cut-off systems

To meet the stringent nitrogen oxides emissions regulations, the recent marine two-stroke engines are equipped with exhaust gas recirculation (EGR) systems. Crossing the boundaries of exhaust control areas requires switching between the engine operating modes associated with the activation or deactivation the EGR system, which imposes challenges to the engine operation. This study aims to develop and numerically test effective control strategies for improving the mode switching of marine two-stroke engines with EGR systems. The investigated engine dynamic model is developed by integrating a zero-dimensional thermodynamic model developed in GT-POWER and the control model developed in MATLAB/Simulink. This model is first validated against the experimentally measured engine performance parameters, and subsequently employed to simulate the engine dynamic operation with mode switching. The simulation results are assessed to quantify the impact of several control strategies on the engine performance. The derived perrformannce parameters time variations demonstrate that the deactivation of the EGR branch and the small engine–turbocharger result in exceeding the manufacturer limits at high loads and increasing the fuel consumption. The proposed load-based control strategies, which employ load thresholds and time delays for the control of the EGR and turbocharging systems activation/deactivation, are proved effective, as the engine performance parameters are retained within their limits and fuel consumption penalties are minimised. This study provides insights for developing the control of the marine engines after-treatment systems, hence contributing towards enhancing shipping sustainability.

Investigation on combustion and emission characteristics of diesel polyoxymethylene dimethyl ethers blend fuels with exhaust gas recirculation and double injection strategy

As a kind of renewable and high oxygen content fuel, polyoxymethylene dimethyl ether (PODE) can be added in diesel to realize energy saving and emissions reduction. To evaluate the combustion and emission characteristics of a diesel engine fueled with diesel and diesel/PODE mixtures, exhaust gas recirculation (EGR) and main-pilot injection strategies with various injection timings were applied. PODE was blended with diesel by volume to form mixtures which were marked as D100 (pure diesel), D90P10 (90% diesel + 10% PODE), and D80P20 (80% diesel + 20% PODE). The results showed that the ignition delay (ID) and combustion duration (CD) of D80P20 were the shortest because of the highest cetane number (CN) and high oxygen content of PODE, indicating more concentrated heat release. At low and medium loads, D80P20 achieved the highest peak heat release ratio (PHRR) and peak combustion temperature (PCT) among the three fuels, and it was 14.3% and 3.6% higher than those of D100. PODE blending with diesel can significantly reduce particulate matter (PM) and D80P20 has the lowest PM emissions at all loads. Compared with D100, both PM and nitrogen oxide (NOx) emissions of PODE blends decreased simultaneously with 20% EGR at all loads. With the increase of pilot-main interval, the ID and CD of all test fuels increased, while the NOx and PM emissions decreased. The conclusions of the present research provide a state of the application in light-duty engines fueled with diesel/PODE blends in future work.

The Impact of Incorporating Varying Proportions of Sugar Beet Waste on the Combustion Process and Emissions in Industrial Burner Fuelled with Conventional Diesel Fuel

Abstract The main objective of the case study is to investigate the effectiveness of using solid fuel additives in conventional diesel fuel for industrial furnaces. The study focuses on utilizing agricultural waste derived from sugar beet plant waste as additives to enhance the combustion process and reduce emissions from industrial burners. In this study, experimental measurent for the flame temperatures inside the furnace while altering the proportions of the solid materials have ben achived. The goal was to assess the impact of different loading from these additives on the combustionprocess. Furthermore, the study involved measuring exhaust gases such as carbon monoxide (CO), carbon dioxide (CO2), unburned hydrocarbon (UH), and nitrogen oxides (NOx). The experimental facility arranment allowed the researchers to evaluate the emissions resulting from the combustion process with the addition of solid fuel additives. By measuring these parameters, the study aimed to understand the effect of utilizing agricultural waste as additives on the burning processes and emission formation in industrial furnaces. These findings can contribute to improving the efficiency of combustion processes, reducing emissions, and promoting the utilization of renewable and sustainable fuel sources in industrial settings. In this study, varying the proportions of solid materials used as additives had an impact on the levels of carbon monoxide (CO), carbon dioxide (CO2), and nitrogen oxides (NOx) in the exhaust gases. By increasing the proportion of solid materials in the fuel mixture resulted in changes in the emission levels. The levels of carbon monoxide in the exhaust gases decreased as the proportion of solid materials increased. While the addition of solid fuel additives did contribute to the production of CO2 due to the combustion of the additives, the overall effect on its levels varied depending on the specific proportions used. Also, the levels of nitrogen oxides in the exhaust gases showed different trends depending on the proportions of solid materials used. Typically, increasing the proportion of solid fuel additives led to reduce NOx emissions. However, this may also depend on other factors such as combustion temperature and the composition of the solid materials.