Increase In NOx Research Articles

Numerical study of NOx formation mechanism in ammonia-hydrogen compound fuel marine engines under varying conditions

Ammonia and hydrogen are considered promising fuels for achieving zero carbon emissions in internal combustion engines. However, the mechanism of NOx formation in ammonia–hydrogen combustion remains insufficiently studied owing to the complex interaction between thermal NOx and fuel NOx. This study investigates the effects of varying equivalence ratios, N2/NH3 ratios, and initial temperatures on NOx formation using a decoupling method. Results show that thermal NOx dominates under all conditions, contributing approximately 64%–75% of total NOx. As the equivalence ratio increases from 0.6 to 1.0, the proportion of thermal NOx decreases by 7.2%. Conversely, increasing the N2/NH3 ratio from 0.8 to 1.2 leads to a reduction in both fuel and thermal NOx, while the relative proportion of thermal NOx increases. The trends in thermal NOx proportion exhibit opposite behavior with respect to equivalence ratio and N2/NH3 ratio. When the inlet temperature rises from 400 K to 480 K, thermal NOx emissions increase by 54.2%. Of the factors studied, temperature has the greatest impact on both thermal and fuel NOx formation. These findings offer valuable insights into NOx emission characteristics for researchers working on ammonia-fueled engines.

Reducing real driving fuel consumption and emissions with a hydraulic hybrid vehicle

We have successfully prototyped and tested the real-driving performance of a hydraulic hybrid heavy commercial vehicle. Hydraulic hybrid driveline technology was fitted to a Euro IV diesel truck equipped with a diesel particulate diffuser/filter and an exhaust gas recirculation system. An AVL portable emissions measurement system was fitted to the test vehicle to quantify gaseous and particle phase emissions species and an on-board diagnostic scan tool was used to obtain data from the trucks electronic control unit. Fuel consumption savings up to 17 % were accomplished in hydraulic hybrid mode when testing on a short urban driving route featuring a high intensity of stop-start activity. Average reductions in solid particle number concentration of 40 % were achieved along with increases in NOx, Hydrocarbons (THCs) and CO. Future work could target improved control system integration of the various driveline components to further reduce fuel consumption and emissions in an improved prototype design.

Global impacts of an extreme solar particle event under different geomagnetic field strengths

Solar particle events (SPEs) are short-lived bursts of high-energy particles from the solar atmosphere and are widely recognized as posing significant economic risks to modern society. Most SPEs are relatively weak and have minor impacts on the Earth's environment, but historic records contain much stronger SPEs which have the potential to alter atmospheric chemistry, impacting climate and biological life. The impacts of such strong SPEs would be far more severe when the Earth's protective geomagnetic field is weak, such as during past geomagnetic excursions or reversals. Here, we model the impacts of an extreme SPE under different geomagnetic field strengths, focusing on changes in atmospheric chemistry and surface radiation using the atmosphere-ocean-chemistry-climate model SOCOL3-MPIOM and the radiation transfer model LibRadtran. Under current geomagnetic conditions, an extreme SPE would increase NOx concentrations in the polar stratosphere and mesosphere, causing reductions in extratropical stratospheric ozone lasting for about a year. In contrast, with no geomagnetic field, there would be a substantial increase in NOx throughout the entire atmosphere, resulting in severe stratospheric ozone depletion for several years. The resulting ground-level ultraviolet (UV) radiation would remain elevated for up to 6 y, leading to increases in UV index up to 20 to 25% and solar-induced DNA damage rates by 40 to 50%. The potential evolutionary impacts of past extreme SPEs remain an important question, while the risks they pose to human health in modern conditions continue to be underestimated.

Экспериментальное исследование влияния температуры распылителя на характеристики сжигания дизельного топлива в атмосферном горелочном устройстве

In this work, using diesel fuel as an example, we studied the combustion characteristics of liquid hydrocarbons when atomized by a high-speed air jet. This approach to spraying liquid fuel in combustion processes has a number of advantages over traditional spraying: the ability to supply fuel with a low degree of purification and to reduce the likelihood of fuel equipment coking. Using an atmospheric burner device with natural air supply into the mixing chamber, the depen¬dences of the composition of intermediate and final combustion products were studied, and the flame temperature was measured at various fuel flow rates and parameters of the atomizing air jet (flow rate, temperature). A comparison was made of the obtained characteristics for equivalent modes at different temperatures of the supplied atomizer. It was found that when heated air is used as a sprayer, higher flame temperatures are ensured, which ensures a more complete fuel burnout and a decrease in CO concentration in the flue gases, but at the same time, a slight increase in NOx is observed.

Joint effects of traffic-related air pollution and hypertensive disorders of pregnancy on maternal postpartum depressive and anxiety symptoms.

Ambient air pollution has been linked to postpartum depression. However, few studies have investigated the effects of traffic-related NOx on postpartum depression and whether any pregnancy-related factors might increase susceptibility. To evaluate the association between traffic-related NOx and postpartum depressive and anxiety symptoms, and effect modification by pregnancy-related hypertension. This study included 453 predominantly low-income Hispanic/Latina women in the MADRES cohort. Daily traffic-related NOx concentrations by road class were estimated using the California LINE-source dispersion model (CALINE4) at participants' residential locations and averaged across pregnancy. Postpartum depressive and anxiety symptoms were evaluated by a validated questionnaire (Postpartum Distress Measure, PDM) at 1, 3, 6 and 12 months postpartum. Multivariate linear regressions were performed to estimate the associations at each timepoint. Interaction terms were added to the linear models to assess effect modification by hypertensive disorders of pregnancy (HDPs). Repeated measurement analyses were conducted by using mixed effect models. We found prenatal traffic-related NOx was associated with increased PDM scores. Specifically, mothers exposed to an IQR (0.22 ppb) increase in NOx from major roads had 3.78% (95% CI: 0.53-7.14%) and 5.27% (95% CI: 0.33-10.45%) significantly higher 3-month and 12-month PDM scores, respectively. Similarly, in repeated measurement analyses, higher NOx from major roads was associated with 3.06% (95% CI: 0.43-5.76%) significantly higher PDM scores across the first year postpartum. Effect modification by HDPs was observed: higher freeway/highway and total NOx among mothers with HDPs were associated with significantly higher PDM scores at 12 months postpartum compared to those without HDPs. This study shows that prenatal traffic-related air pollution was associated with postpartum depressive and anxiety symptoms. The study also found novel evidence of greater susceptibility among women with HDPs, which advances the understanding of the relationships between air pollution, maternal cardiometabolic health during pregnancy and postpartum mental health. Our study has potential implications for clinical intervention to mitigate the effects of traffic-related pollution on postpartum mental health disorders. The findings can also offer valuable insights into urban planning strategies concerning the implementation of emission control measures and the creation of green spaces.

Efficient nitrogen removal from mainstream sewage in tidal flow constructed wetlands: Targeted migration and conducive spatial distribution for pollutants removal

The tidal flow constructed wetland (TFCW) effectively removes nitrogen from mainstream wastewater but encounters limitations in denitrification, resulting in the accumulation of nitrate and nitrite nitrogen (NOx--N). In this study, we investigated the spatial distribution characteristics of pollutants and migration-transformation processes within the TFCW using the stratified analysis theories proposed. The results indicated that during the influent stage, 82.60 % of ammonia nitrogen (NH4+-N) and 87.77 % of COD were adsorbed by the top and middle layers. In the drain stage's oxygen-rich environment, microorganisms and atmospheric oxygen oxidized NH4+-N to NOx--N, achieving in-situ regeneration of NH4+-N adsorption sites. Furthermore, 61.87 % of the NOx--N was washed into the bottom in the next influent stage, subsequently adsorbed by the biofilm, and finally reduced to gaseous nitrogen using carbon source as the electron donor at the drain stage. Consequently, inconsistent locations of carbon source and NOx--N were identified as limiting factors for denitrification in TFCW. Based on this, the study designed a two-way influent tide flow constructed wetland (TTFCW) by altering the influent pattern. It facilitated targeted carbon source addition for denitrification, resulting in a 3.30-fold improvement in actual carbon source utilization efficiency of TFCW. Ultimately, this approach resulted in a notable increase in NOx--N removal rate by 64.51 %, accompanied by a 28.32 % reduction in accumulation levels. This study fills the research gap in the internal distribution and migration-transformation of pollutants within TFCW, providing methods support for enhancing nitrogen removal in TFCW and ideas for denitrification in mainstream wastewater.

The influence of residual gas on ozone-assisted combustion in an HCCI reciprocating engine

This work is an investigation on the influence of both residual gas and ozone on the combustion process in an HCCI engine fuelled with iso-octane/air/ozone mixtures and on how ozone reacts with residual gases. It is well known that ozone releases oxygen atoms mainly through the O3+M⇄O2+O+M reaction and this may lead to an improvement of the engine combustion. Nevertheless, the chemical interaction between ozone and the species in the residual gas has not yet been investigated in the literature. CFD simulations of a closed-valve engine cycle have been carried out by using an axisymmetric domain. The model has been validated against experimental data and a parametric analysis has been carried out to assess different compositions and amounts of residual gases on the engine performance. The results show that during compression ozone enables Low-Temperature Combustion, with a small amount of heat released before the occurrence of auto-ignition. The combustion is faster and advanced with a reduction of UHCs and an increase of NOx. The results show that the influence of ozone is more effective as the mass of residual gases increases. With an ozone concentration of 35 ppm at IVC the gross work per cycle increases by 2.52 %, 3.58 % and 5.7 %, compared to the case without ozone, with 0 %, 5 % and 10 % by mass of residual gases, respectively. It can be concluded that ozone is more beneficial for cases where combustion is slower due to the higher amount of residual gases.

Association between combined exposure to ambient air pollutants, genetic risk, and incident gout risk: A prospective cohort study in the UK Biobank

BackgroundLimited research has been conducted on the association between long-term exposure to air pollutants and the incidence of gout. ObjectivesThis study aims to assess the individual and combined effects of prolonged exposure to five air pollutants (NO2, NOx, PM10, PMcoarse and PM2.522NO2, nitrogen dioxide; NOx, nitrogen oxides; PM10, particulate matter with diameters ≤ 10 µm; PMcoarse, particulate matter with diameters between 2.5 and 10 µm;PM2.5, particulate matter with diameters ≤ 2.5 µm.) on the incidence of gout among 458,884 initially gout-free participants enrolled in the UK Biobank. MethodsEmploying a land use regression model, we utilized an estimation method to ascertain the annual concentrations of the five air pollutants. Subsequently, we devised a weighted air pollution score to facilitate a comprehensive evaluation of exposure. The Cox proportional hazards model was utilized to investigate the association between ambient air pollution and gout risk. Interaction and stratification analyses were conducted to evaluate age, sex, BMI, and genetic predisposition as potential effect modifiers in the air pollution-gout relationship. Furthermore, mediation analyses were conducted to explore the potential involvement of biomarkers in mediating the association between air pollution and gout. ResultsOver a median follow-up time of 12.0 years, 7,927 cases of gout were diagnosed. Significant associations were observed between the risk of gout and a per IQR increase in NO2 (HR33HR, hazard ratio.: 1.05, 95 % CI44CI, confidence interval.: 1.02–1.08, p = 0.003), NOx (HR: 1.04, 95 % CI: 1.01–1.06, p = 0.003), and PM2.5 (HR: 1.03, 95 % CI: 1.00–1.06, p = 0.030). Per IQR increase in the air pollution score was associated with an elevated risk of gout (p = 0.005). Stratified analysis revealed a significant correlation between the air pollution score and gout risk in participants ≥60 years (HR: 1.05, 95 % CI: 1.02–1.09, p = 0.005), but not in those <60 years (p = 0.793), indicating a significant interaction effect with age (p-interaction=0.009). Mediation analyses identified five serum biomarkers (SUA:15.87 %, VITD: 5.04 %, LDLD: 3.34 %, GGT: 1.90 %, AST: 1.56 %55UA, urate; HDL, high-density lipoprotein; VITD, vitamin D; LDLD, low density lipoprotein direct; GGT, gamma glutamyltransferase; AST, aspartate aminotransferase.) with potential mediation effects on this association. ConclusionsLong-term exposure to air pollutants, particularly among the elderly population, is associated with an increased risk of gout. The underlying mechanisms of these associations may involve the participation of five serum biomarkers.

Trend analysis of measured surface ozone at the megacity of Tehran for the summertime 2007–2021

High concentrations of surface ozone in urban and industrial regions worldwide have been a major air quality issue. Tehran, as the capital and the most populous city of Iran, has experienced intense ambient air pollution over the last three decades. This study aims to assess the long-term trends of ozone over this city in recent decades. Data series of maximum 8-h daily average (MDA8) ozone were obtained for the period between 2007 and 2021. To determine the MDA8 ozone trend attributed to the long-term changes in ozone precursor emissions, we isolated the effects of meteorology and short-term ozone variability. The results show a downward trend from 2007 to 2014 (P1) and an upward trend from 2014 onward (P2). The long-term precursor emissions changes contribute to a 29.1% negative trend (=−0.7 ppb year−1) over P1 and an 8.95% upward trend (=0.1 ppb year−1) over P2. To find the causes of the trend transition, we investigated the relationship between the adjusted MDA8 and several ozone precursors, namely NOx and CO. It is found that, over P1, the dominant chemistry regime is mixed, in which the decline of CO and NOx (attributed to industrial sources) is associated with the downward trend of ozone. On the other hand, the upward trend of ozone over P2 is associated with an increase in NOx mostly attributed to road transport (passenger cars) and residential sectors.

Combustion of diesel fuel sprayed with cold or heated air in an atmospheric burner

In this work the combustion characteristics of liquid hydrocarbons when atomized by a high speed air jet were studied, using diesel fuel as an example. This approach to spraying liquid fuel in combustion processes has a number of advantages over traditional spraying: the ability to supply fuel with a low degree of purification, reducing the chance of coking of fuel equipment. Using an atmospheric burner device with natural air supply into the mixing chamber, the dependences of the composition of intermediate and final combustion products were studied, and the flame temperature was measured at various fuel flow rates and parameters of the atomizing air jet (flow rate, temperature). A comparison of the obtained characteristics was made for equivalent modes at different temperatures of the supplied atomizer. It was found that when heated air is used as a sprayer, higher flame temperatures are ensured, which ensures more complete fuel burnout and a decrease in CO concentration in the flue gases, but at the same time, a slight increase in NOx was observed.

How to perceive and map the synergy between CO2 and air pollutants: Observation, measurement, and validation from a case study of China

Cities occupy a central position in addressing climate change and promoting sustainable regional development. Synergistic control of urban gas emissions at the city level is one of the main issues typically explored. The confounding effect and the interactions between the urban indicators of population and area have been ignored in previous studies. In this study, we examined the spatial distribution characteristics and synergy between greenhouse gases (CO2) and air pollutants (SO2 and NOX) using spatial population and gas emission data. By upgrading the city clustering algorithm (CCA), we established a method for defining active areas of gas emissions (spatial element-coupled clustering, SECC) and identified active areas of gas emissions in China. In this study, we created a research framework that can simultaneously consider the effects of population and area, as well as the possible interactions between these indicators in active areas. The superlinear scaling relationship between the above three gases was revealed at the active zone level, and the existence of synergy between the emission patterns of the three gases was confirmed. Via further model application, we measured the synergistic efficiency of the three gases. It was found that for every 1% increase in SO2 and NOX in an active zone, CO2 increases by 0.86%. In this study, we explored a new perspective and approach to explain the synergy between greenhouse gases and air pollutants. This is essential to promote national competition among cities to achieve synergistic control of CO2 and local air pollutants.

Association of air pollution and risk of chronic kidney disease: A systematic review and meta-analysis.

Although epidemiological studies have evaluated the association between ambient air pollution and chronic kidney disease (CKD), the results remain mixed. To clarify the nature of the association, we conducted a comprehensive systematic review and meta-analysis to assess the global relationship between air pollution and CKD. The Web of Science, PubMed, Embase and Cochrane Library databases systematically were searched for studies published up to July 2023 and included 32 studies that met specific criteria. The random effects model was used to derive overall risk estimates for each pollutant. The meta-analysis estimated odds ratio (ORs) of risk for CKD were 1.42 (95% confidence interval [CI]: 1.31-1.54) for each 10 μg/m3 increase in PM2.5 ; 1.20 (95% CI: 1.14-1.26) for each 10 μg/m3 increase in PM10 ; 1.07 (95% CI: 1.05-1.09) for each 10 μg/m3 increase in NO2 ; 1.03 (95% CI: 1.02-1.03) for each 10 μg/m3 increase in NOX ; 1.07 (95% CI: 1.01-1.12) for each 1 ppb increase in SO2 ; 1.03 (95% CI: 1.00-1.05) for each 0.1 ppm increase in CO. Subgroup analysis showed that this effect varied by gender ratio, age, study design, exposure assessment method, and income level. Furthermore, PM2.5 , PM10 , and NO2 had negative effects on CKD even within the World Health Organization-recommended acceptable concentrations. Our results further confirmed the adverse effect of air pollution on the risk of CKD. These findings can contribute to enhance the awareness of the importance of reducing air pollution among public health officials and policymakers.

A comparative study of the impact on combustion and emission characteristics of nanoparticle‐based fuel additives in the internal combustion engine

AbstractThe search for an effective solution to improve performance and emission characteristics of internal combustion (IC) engines used in the commercial sector is regarded as one of the most important and essential issues in recent years due to increasing levels of pollution. Nanoparticles with their additive ability to increase fuel reactivity and atomization, due to their large surface area and high heat transfer coefficient, can improve the performance and emission characteristics of a fuel. This review highlights the use of nanoparticles as fuel additives to enhance the emission and performance characteristics of IC engines. Detailed comparisons of performance, emission, and combustion characteristics of IC engines using fuels blended with nanoparticles have been done. Nanoparticles were observed to be an oxygen buffer for fuel combustion and boost fuel atomization, thus enhancing engine performance. While alumina exhibited a decrease in levels of HC and CO but a considerable increase in NOx, graphene nanoparticles and ceria were found to be particularly effective in enhancing engine performance. Detailed study has been done on other nanoparticles, including metal‐oxide, nonmetal‐oxide as well as carbon nanoparticles. Overall, the use of nanoparticles can enhance the thermophysical characteristics of fuels, improving the emission and performance characteristics of engines. The review suggests that selecting the right dosage and variety of nanoparticles is crucial for optimizing engine performance, and thus directly helps in tackling the ongoing pollution problem.

Numerical simulation of the combustion chamber and performance analysis of microalgae-based biodiesel/diesel-powered CI engine: An axisymmetric flow approach

This study presents a comprehensive analysis of the combustion chamber characteristics of a variable compression ratio compression ignition engine powered with microalgae biodiesel/diesel and their impact on engine performance and emissions. Both numerical and experimental methods have been employed to study the problem. A computational fluid dynamics method is used to study the axisymmetric flow in the cylindrical combustion chamber. Numerical simulations are obtained by solving time-independent steady, incompressible Navier-Stokes equation in a two-dimensional cylindrical coordinate system. Fluid flow characteristics, such as velocity vector field, streamlines, and pressure distribution are presented for different biodiesel blends. The velocity vector field analysis shows that biodiesel blends exhibit high velocities near the axisymmetric wall region. Swirl motion generated near the outer periphery of the combustion chamber influences the flow patterns. The experimental study involves the engine performance and its emissions. Due to the increase of biodiesel blend ratios in B20 (20% biodiesel and 80% diesel), B40 (40% biodiesel and 60% diesel), B50 (50% biodiesel and 50% diesel), and B100 (100% biodiesel), the brake thermal efficiency (BTE) decreases for a given brake power. B20, B100, and diesel exhibit 32.87%, 29.15%, and 34.45% BTE respectively. Higher brake-specific fuel consumption is obtained at no-load engine operations due to incomplete combustion of fuel. B20, B40, B50, and B100 show reductions of 16.04%, 20.85%, 25.66%, and 32.08% CO, respectively, as compared to diesel. HC emissions are very low for all biodiesel blends, while B20 exhibits a decrease of 7.35% HC compared to diesel. However, NOx emissions increase with the biodiesel blend ratio, with B100 exhibiting a 22.56% increase in NOx compared to diesel. Smoke emissions decrease with an increase in the biodiesel blend ratio, while B20 shows a 4.64% reduction. Results show that B20 offers a favorable balance between emissions reduction and engine performance. This study determines the biodiesel combustion characteristics and insights for the practical implementation of biodiesel blends in the transportation and energy sectors.

Experimental investigation of the influence of pre-chamber structural parameters on combustion and emission characteristics of a high compression ratio SI engine

The passive pre-chamber exhibits great potential for practical applications in the internal combustion engine due to its simple structure. However, it faces difficulties in scavenging process, making optimization of pre-chamber structure particularly important. In this study, the effects of pre-chamber ignition systems with different structures and original spark ignition were conducted on a high compression ratio direct-injection SI engine to investigate the combustion, performance, and emission characteristics. The results show that the increase in pre-chamber volume weakens the in-cylinder combustion process and engine performance, while increasing the pre-chamber orifice diameter can enhance the combustion stability at medium to high loads, but will weaken the engine performance at low load. Compared to spark ignition, pre-chamber ignition results in an earlier 50% combustion position, a shorter combustion duration and lower COVIMEP, with these effects becoming stronger as load increases. At high load, the pre-chamber ignition (PC1) advances the 50% combustion position by 5.6°CA and shortens the combustion duration by 16.7%. In addition, the indicated thermal efficiency of the pre-chamber ignition achieves an increase of 0.84% at the optimal point and 2.5% at high load. Overall, using the smaller orifice diameter and volume in the pre-chamber can improve in-cylinder combustion process and increase thermal efficiency across the load range. For emission analysis, the pre-chamber ignition leads to an increase in NOx and HC emissions due to the influence of in-cylinder combustion temperature and quenching effect, while the CO emissions are similar to spark ignition.

Reducing the Harmful Exhaust Emissions from the Diesel Engine of the Tractor CASE JX75T by using the EFWP Filter at Different Engine Speeds

In this investigation, the influence of using the EFWP filter on the tractor exhaust emissions was determined. A Water and paper filter is a filter designed to operate as a filter for the exhaust for the reduction of the harmful gas (CO, CO2, NOx, and HC) emission from the engine of the tractor. Emissions experiments were carried out on CASE JX75T tractor at different engine speeds are 750, 1000, 1250, 1500, 1750, 2000, and 2250 rpm. All engine speed of the tractor underwent experimentation before the installation of the EFWP filter and after installation it. The noises and Bsfec also were measured when the two cases. Each engine speed was tested for approximately 20 minutes in two cases. The results showed a significant (P≤0.05) decreasing in carbon monoxide CO (51.40%), carbon dioxide CO2 (25%), nitrogen oxides NOx (43.43%) and hydrocarbons HC (60.98%) emissions and also, the noises reduced by 25.38% and there was no significant increase in the BSFC (5.34% only) after the EFWP filter was put in the tractor exhaust. The results also showed that increasing the engine speed from 750 to 2250 rpm led to significant increases in CO2, NOx, and HC emissions, while decreased the CO emission. Also, the increased by a percentage of 155.88 and 159.38 % in the case using the EFWP filter and without using it (the ordinary case) respectively. Using the EFWP filter reduced the noises not overridden internationally permitted standards (65 dB).

Investigation of ammonia cracking combined with lean-burn operation for zero-carbon combustion and NO/N2O/NO2 improvements

Ammonia has received significant attention as a carbon-free fuel and a promising carrier of hydrogen. Ammonia cracking presents an effective method for on-line hydrogen production, eliminating the need for hydrogen transportation and storage. This paper aims to study the comprehensive impacts of ammonia cracking ratio (CR) and equivalence ratio (ER) on combustion performance and NO/N2O/NO2 behaviors under lean-burn operation mode. The ammonia/hydrogen mechanism was updated and simplified to enhance the calculation efficiency in 3D simulation. Visualization measurements for flame propagation and NO and 3D simulations were simultaneously performed in a constant volume combustion chamber (CVCC). The results showed that ammonia blending with the cracked gas of H2/N2 for CR can significantly enhance the combustion rate under lean-burn operation at an ER of 0.5. Nevertheless, this enhancement leads to an increase in NOx due to elevated OH and HNO formation, regardless of N2 separation. In the context of varying ER, ranging from 0.5 to 0.3, the study revealed that increasing CR combined by decreasing ER at a certain point can sustain a higher combustion rate while reducing NOx emissions. For instance, CR45ER0.4 yields a much shorter combustion duration and lower NOx compared to pure ammonia at an ER of 1.0. However, a further increase in CR, such as CR80ER0.3, results in higher NOx emissions again. Moreover, complete cracking or separation from the non-cracked ammonia proves favorable for NOx elimination due to the absence of fuel-NO. The current study provides insights on high-efficiency and clean zero-carbon combustion technology.

Impact of Hydrogen on Emission Reduction in a CI Engine when Fuelled with Blends of Diesel-Waste Cooking Biodiesel

Waste utilisation and emission of greenhouse gases are two of the world's most pressing challenges today. This study seeks to solve the problem generated by the disposal of Waste Cooking Oil (WCO) as a tiny step forward in contributing to the reduction of waste disposal. WCO has a high potential as a bio fuel for internal combustion engines, hence it was chosen for this investigation. WCO of 20% and diesel 80% is used. This study looks at the performance, combustion and emission parameters of a dual fuel compression ignition engine running on WCO biodiesel with a hydrogen additive at atmospheric condition. The parametric study include variation in engine load (0-18 kg) and hydrogen flow rate (3, 6, 9 LPM). The experiment was conducted on a four-stroke diesel (computerized), single cylinder, water cooled power at 5.2 kW at 1500rpm Kirloskar engine. From the experiment overall parametric variation of 35.38%, 34.06% and 32.37% of brake thermal efficiency was obtained and emission was observed. However, with increase of hydrogen flow rate resulted in increased engine performance, increase in CO, NOx and reduction in emission of UBHC and CO2.

Space-Based Observations of Ozone Precursors within California Wildfire Plumes and the Impacts on Ozone-NOx-VOC Chemistry.

The frequency of wildfires in the western United States has escalated in recent decades. Here we examine the impacts of wildfires on ground-level ozone (O3) precursors and the O3-NOx-VOC chemistry from the source to downwind urban areas. We use satellite retrievals of nitrogen dioxide (NO2) and formaldehyde (HCHO, an indicator of VOC) from the Tropospheric Monitoring Instrument (TROPOMI) to track the evolution of O3 precursors from wildfires over California from 2018 to 2020. We improved these satellite retrievals by updating the a priori profiles and explicitly accounting for the effects of smoke aerosols. TROPOMI observations reveal that the extensive and intense fire smoke in 2020 led to an overall increase in statewide annual average HCHO and NO2 columns by 16% and 9%. The increase in the level of NO2 offsets the anthropogenic NOx emission reduction from the COVID-19 lockdown. The enhancement of NO2 within fire plumes is concentrated near the regions actively burning, whereas the enhancement of HCHO is far-reaching, extending from the source regions to urban areas downwind due to the secondary production of HCHO from longer-lived VOCs such as ethene. Consequently, a larger increase in NOx occurs in NOx-limited source regions, while a greater increase in HCHO occurs in VOC-limited urban areas, both contributing to more efficient O3 production.

Effect mechanism and quantitative analysis of injector faults on diesel engine performance

The nozzle deterioration, caused by carbon deposition, cavitation erosion, and other reasons, has a great influence on the power performance, emissions, and thermal load of the direct injection (DI) engine. To understand the manifold effects of nozzle fault on engines, a systematic explanation for the diverse fault phenomena and effect mechanism of nozzle abnormality on the engine performance is needed. The joint action of orifice diameter and fuel spread direction on the performance of a double-swirl diesel engine are numerically revealed and decoupled. The results show that the engine power performance is mainly affected by the change of orifice diameter, while the abnormal spray direction has a great influence on the emissions and the piston surface thermal load. Insufficient spray tilt angle leads to a more concentrated fuel distribution because the fuel of the faulty orifice is not effectively channeled and dispersed by the circular ridge, which causes a 15.29% increase in NOx and an 8.73% increase in soot emissions. Spray circumferential offset leads to increased soot, decreased NOx, and slightly decreased power due to asymmetric fuel distribution. Some fuel is directly injected and burned in the clearance between the piston crown and cylinder head due to the abnormal spray direction, which causes the maximum heat flux at the piston crown to be about 1.8 times that under normal state, greatly increasing the possibility of piston damage. In contrast, the spray circumferential offset mainly causes the position change of the thermal load, but not the magnitude change.