PM10 emission

M. Rypdal and K. Rypdal, Late Quaternary temperature variability described as abrupt transitions on a 1/f noise background, Eart Syst. Dynam., 7, 281-293, 2016. doi: 10.5294/esd-7-281-2016. http://www.earth-syst-dynam.net/7/281/2016/esd-7-281-2016.pdf. Discussion: http://www.earth-syst-dynam.net/7/281/2016/esd-7281-2016-discussion.html analysis of output from the ZC-model. This implies that the L&V results do not reject the linear response hypothesis.

In a context of energy transition, wind energy is a source of clean energy with the potential of partially satisfying the growing demand. The main problem of this type of energy, and other types of renewable energy remains the discontinuity of the electric power produced in different scales, inducing large fluctuations also called intermittency. This intermittency of wind energy is inherent to the turbulent nature of wind. Here, we consider the relation between velocity and power output with two wind turbine databases. We focus on joint relations with Fourrier analysis, empirical mode decomposition (EMD), Time-dependent intrinsic correlation (TDIC). We also consider the causality using a new method of analysis of the causality between two time series.

This paper investigates the existence of chaos in concentration dynamics of particulate matter with an aerodynamic diameter less than or equal to 10 μm (PM 10) in the greater Athens area (GAA), Greece. It reports findings on three 16-year PM 10 time series recorded by three different air pollution monitoring stations located in GAA and examines if critical fractal epochs with long memory exist. Detrended Fluctuation Analysis (DFA) and Rescaled Range (R/S) Analysis were used via sliding windows of approximately 1-month duration. In all PM 10 time series, several segments were found with critical fractal behaviour and hidden long-memory patterns. All these segments exhibited Hurst exponents above 0.75 and DFA exponents above 1.75. Twelve PM 10 segments with fractality and long memory were commonly identified by both techniques. In one case, long memory was identified concurrently across all three air pollution monitoring stations and in another case, across two stations. The importance of the agreement between two different and independent chaos-analysis techniques is discussed in association with the proper selection of threshold values. This is the second time to address chaos in PM 10 data series in GAA, and the first time to combine two widely accepted techniques, DFA and R/S analysis.

Spark ignition-controlled auto-ignition is a combustion strategy to overcome the challenges in a homogeneous charge compression ignition or controlled auto-ignition combustion which has a limited operation region and does not have any direct control of the combustion timing. However, the spark ignition-controlled auto-ignition combustion can result in a large cyclic variability due to two main distinctive combustion phases developing initially by flame propagation and following controlled auto-ignition combustion throughout an engine cycle. Characterization of combustion development is, therefore, required to maintain a stable engine operation under spark ignition-controlled auto-ignition combustion. In this research, experimental studies were carried out to investigate spark ignition-controlled auto-ignition combustion development at different spark advances and intake air temperatures. Combustion analyses were performed employing pressure-based heat release and mass fraction burn curve to determine the main combustion parameters along with transition points (corresponding to crank angles) to controlled auto-ignition and mass fraction burnt by flame propagation. The results reveal that transition point has a strong correlation with crank angle position where 10% of fuel mass consumed combustion phasing rather than mass fraction burnt by flame propagation at the same intake air temperature. The cycles with a higher mass fraction burnt by flame propagation can result from early flame development at the advanced spark timings (at 230 and 240°CA) while the slow flame development at a spark timing of 220°CA due to late transition point corresponding to crank angle occurred. Besides, it is also found that flame propagation phase more contributes to the cyclic variation in the whole combustion process.

Particulate matter (PM) pollution poses a significant threat to human health. Greenery, particularly trees, can act as effective filters for PM, reducing associated health risks. Previous studies have indicated that tree traits play a crucial role in determining the amount of PM accumulated on leaves, although findings have often been sitespecific. To comprehensively investigate the key factors influencing PM binding to leaves across diverse tree species and geographical locations, we conducted an extensive analysis using data extracted from 57 publications. The data covers 11 countries and 190 tree species from 1996 to 2021. We categorized tree species into functional groups: evergreen conifers, deciduous conifers, deciduous broadleaves, and evergreen broadleaves based on leaf habit and phylogeny. Evergreen conifers exhibited the highest PM accumulation on leaves, and in general, evergreen leaves accumulated more PM compared to deciduous leaves across all PM size classes. Specific leaf traits, such as epicuticular wax, played a significant role. The highest PM loads on leaves were observed in peri-urban areas along the rural-peri-urban-urban gradient. However, the availability of global data was skewed, with most data originating from urban and peri-urban areas, primarily from China and Poland. Among different climate zones, substantial data were only available for warm temperate and cold steppe climate zones. Understanding the problem of PM pollution and the role of greenery in urban environments is crucial for monitoring and controlling PM pollution. Our systematic review of the literature highlights the variation on PM loading among different vegetation types with varying leaf characteristics. Notably, epicuticular wax emerged as a marker trait that exhibited variability across PM size fractions and different vegetation types. In conclusion, this review emphasizes the importance of greenery in mitigation PM pollution. Our findings underscore the significance of tree traits in PM binding. However, lack of data stresses the need for further research and data collection initiatives.

Due to African dust, the Caribbean area is known to have one of the highest incidences of asthma on the planet. Consequently, it is crucial to dissociate the impact of local sources from large scale sources in this region. The aim of this study was to estimate the PM10 detection threshold for dusty events using a statistical approach and a dynamic approach. To carry out this analysis, PM10 time series from Martinique (MAR), Guadeloupe (GPE) and Puerto-Rico (PR) were used between 2006 and 2016. The statistical analysis highlighted that the distance from the African coast is a key feature for PM10 concentrations distribution with the highest at MAR (26.52 μg/m3) and the lowest at PR (24.42 μg/m3). The probability density function analysis showed that MAR-GPE-PR distributions converge towards a same point between the first and the second maximum probability value at 28 μg/m3. The dynamical analysis with the Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) an...

Supplementing petroleum fuels with sustainable and renewable alternatives is a good option for increasing the sustainability of transportation fuels. Alcohols are particularly attractive blendstocks for spark ignition engines, mainly due to their desirable fuel properties including high octane, evaporative cooling, and reduced sooting propensity. Although the use of SI engines is widespread around the world, predominately for light duty vehicles, concerns about CO 2 emissions and other sustainability issues necessitate increased engine efficiencies, reduced tailpipe pollutants, and lower lifecycle carbon emissions. The intelligent blending of C2-C4 alcohols into motor gasoline is a viable method for achieving these goals. There are a multitude of ways to produce renewable alcohols such as through fermentation from first-generation feedstocks (sugar and corn) and second-generation feedstocks (lignocellulosic biomass), or by gasification and mixed alcohol fuel synthesis routes from lignocellulosic biomass. Currently ethanol is extensively used in motor gasoline fuels worldwide and although many have proposed the use of C3 and C4 alcohols in motor gasoline as an improvement over ethanol, the higher cost of production and lack of clear definition as to their benefit over ethanol when blended into motor gasoline have led to slow acceptance into the market. In this review, special emphasis is placed on the effects of blending C3 and C4 alcohols into motor gasoline in terms of physicochemical properties, volatility behavior, and engine performance when compared to ethanol blends. Furthermore, the impact of blending C3 and C4 alcohols with gasoline on emission (particulate matter, nitrogen oxides, carbon monoxide, hydrocarbons, and unregulated oxygenates) and combustion (volumetric efficiency, thermal efficiency, fuel consumption, and cold performance) characteristics is discussed. Although there are some disagreements in the literature over the effect of alcohols predominately around the type of SI engine, i.e., port fuel injected versus direct fuel injected and engine operating mode, generally it is stated that alcohols can potentially reduce soot, unburned hydrocarbons and CO emissions while increasing thermal efficiency when proper engine configuration/calibration is used. Finally, research that must be conducted to find the optimum combination of alcohol blends and engine configurations is highlighted and discussed.

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In the study are presented the results of co-combustion of biodiesel B100 with ethanol fuel as blend. The 1-cylinder direct injection compression ignition engine was used during the study. Tests were conducted at a constant angle of fuel injection and constant rotational speed equal to 1500 rpm. Results of thermal cycle parameters and emission characteristics are presented. On the basis of results stated that ethanol fuel fraction in blend causes the increase in peak heat release rate. With the increase in ethanol fuel fraction the ignition delay increased but combustion duration decreased. With the increase in ethanol fuel fraction in blend thermal efficiency increased as well. It also noticed almost constant emission of THC, the increase in NOx emissions and decrease emissions in CO and CO2.

The complexity of spatial-temporal air pollutant concentration dynamics requires innovative modeling investigation approaches. The details of non-linear nature of pollutant behavior cannot be revealed by conventional approaches, but fractal and Hurst rescaled analyses allow the quantification of pollutant dynamics structure via self-similarity and scale invariance. In this study, we applied multiscale multifractal analysis (MMA) to investigate the complex time-series of criteria air pollutants (PM 10 , PM 2.5 , NO X , SO 2 , CO and O 3). The results showed that PM 10 and PM 2.5 concentrations are more stable compared to gaseous oxides and exhibit less prominent multifractality. Out of gaseous contaminants, CO is confirmed to be less chemically reactive than NO, NO 2 , NO x , SO 2 and O 3 under the same atmospheric conditions in urban and semi-urban area. As concluded, the multifractal analysis presented herein can enhance our understanding of specific pollutant dynamic features and support relevant sectors to control the pollutant release and distribution.

LTC was researched by introducing an 80% mass fraction of n-butanol in reactivity 9 controlled compression ignition (RCCI) mode. A 60% mass fraction of n-butanol was port fuel injected 10 (PFI) and the additional 20% was direct injected through a blend of n-butanol (Bu) with Fischer-Tropsch 11 gas to liquid synthetic paraffinic kerosene (GTL) or ULSD as reference. The blended fuels GTL20-Bu80 12 and ULSD20-Bu80 have reduced cetane for improved combustion phasing control compared to the 13 reference RCCI mode with direct injection of neat ULSD and n-Butanol PFI (ULSD40-Bu60). RCCI 14 strategies delayed ignition and increased peak heat release rates due to prolonged mixing time and reactivity 15 stratification, inducing faster flame speeds. In RCCI mode, the ringing intensity (RI) increased up to 85% 16 higher than in CDC. NOx and soot were reduced up to 90% with ULSD40-Bu60 compared to CDC. The 17 butanol blends decreased CO by 25% compared to ULSD RCCI. CO levels overlay each other for GTL20-18 Bu80 and ULSD20-Bu80 across loads, suggesting that the butanol is the influencing factor. ULSD and 19 ULSD20-Bu80 RCCI increased mechanical efficiencies compared to CDC by 3-4% across loads. ULSD20-20 Bu80 had the lowest cetane and displayed the greatest improvement in the overall emissions and efficiencies 21 in RCCI compared to CDC.

The auto-ignition characteristics of diethyl ether (DEE)/ethanol mixtures are investigated in compression ignition (CI) engines both numerically and experimentally. While DEE has a higher derived cetane number (DCN) of 139, ethanol exhibits poor ignition characteristics with a DCN of 8. DEE was used as an ignition promoter for the operation of ethanol in a CI engine. Mixtures of DEE and ethanol (DE), i.e., DE75 (75% DEE + 25% ethanol), DE50 (50% DEE + 50% ethanol) and DE25 (25% DEE + 75% ethanol), were tested in a CI engine. While DE75 and DE50 auto-ignited at an inlet air pressure of 1.5 bar, DE25 failed to auto-ignite even at boosted pressure of 2 bar. The peak in-cylinder pressure for diesel and DE75 were comparable, while DE50 showed reduced peak in-cylinder pressure with delayed start of combustion (SOC). Numerical simulations were conducted to study the engine combustion characteristics of DE mixture. A comprehensive detailed chemical kinetic model was created to represent the combustion of DE mixtures. The detailed mechanism was then reduced using standard direct relation graph (DRG-X) method and coupled with 3D CFD code, CONVERGE, to simulate the experimental data. The simulation results showed that the effects of physical properties on DE50 combustion are negligible. Simulations of DE50 mixture revealed that the combustion is nearly homogenous, while diesel (n-heptane used as a surrogate) and DE75 showed similar combustion behavior with flame liftoff and diffusion controlled combustion. Diesel exhibited auto-ignition at an equivalence ratio of 2, while DE75 and DE50 showed auto-ignition in the equivalence ratio range of 1-1.5 and 0-1, respectively. The experiments and numerical simulations demonstrate how the high reactivity of DEE supports the auto-ignition of ethanol, while ethanol acts as a radical scavenger.

The thermal effect of urban impervious surfaces (UIS) is a complex problem. It is thus necessary to study the relationship between UIS and land surface temperatures (LST) using complexity science theory and methods. This paper investigates the long-range crosscorrelation between UIS and LST with detrended crosscorrelation analysis and multifractal detrended crosscorrelation analysis, utilizing data from downtown Shanghai, China. UIS estimates were obtained from linear spectral mixture analysis, and LST was retrieved through application of the mono-window algorithm, using Landsat Thematic Mapper and Enhanced Thematic Mapper Plus data for 1997-2010. These results highlight a positive long-range cross-correlation between UIS and LST across People's Square in Shanghai. LST has a long memory for a certain spatial range of UIS values, such that a large increment in UIS is likely to be followed by a large increment in LST. While the multifractal long-range crosscorrelation between UIS and LST was observed over a longer time period in the WE direction (2002-2010) than in the N-S (2007-2010), these observed correlations show a weakening during the study period as urbanization increased.

The climate change issue has become a growing concern due to the increasing greenhouse gas emissions. To achieve carbon neutrality for mitigating the climate problem, the oxy-fuel combustion (OFC) technique on internal combustion engines (ICEs) has attracted much attention. Furthermore, the water injection (WI) strategy was proven effective in improving the combustion process and thermal efficiency in engines under OFC mode. However, WI strategy effects on gasoline direct injection (GDI) engines fuelled with gasoline–alcohol blends have not been reported. This study quantitatively analysed WI mass and timing effects on oxy-fuel combustion performance from a GDI engine fuelled with E10 (10% ethanol and 90% gasoline in mass) by simulation. The results show that equivalent brake-specific fuel consumption (BSFCE) shows a monotonically decreasing trend with the increase in the water–fuel mass ratio (Rwf) from 0 to 0.2. However, further increasing Rwf would cause a deterioration in BSFCE ...

The operating conditions of injectors in spark ignition engines with direct fuel injection make them susceptible to coking, which leads to a reduced quality of fuel atomization. This can be observed by a drop in performance and an increase in exhaust emissions, especially particulate matter. One effective method of reducing injector coking is by using detergentdispersing gasoline additives. The article describes the effect of using an admixture with a varied alcohol content on the quantitative and qualitative fuel atomization indicators. The research consisted of a 48-hour engine test, done in accordance with the CEC F-113-KC procedure (CEC-F-113 test). After each test cycle, the injectors underwent optical tests with the use of an isochoric chamber. The spray penetration and surface area were analyzed at a set of different fuel injection parameter values. The research performed resulted in determining the influence of each tested admixture on the change of injection time and on the...

District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand-outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations.

This study aims to experimentally investigate the effects of using different percentages of ethanol-biodiesel-diesel blends in diesel internal combustion engines and to analyze energy and combustion parameters. The experiments were conducted on a single-cylinder, four-stroke, air-cooled, and constant-speed diesel generator set with a rated electrical power of 4.5 kW and 79% of full engine load (3.54kW). Temperature, fuel flow, AVL pressure, and rotation sensors were installed on the crankshaft and inside the cylinder. The fuels used were commercial diesel (S-10) and blends with 1%, 2%, and 3% of anhydrous ethanol added to diesel, changing the injection pressure in only one blend. The results show a decrease in thermal efficiency and an increase in fuel consumption, in addition to an increase in ignition delay, an increase in combustion duration, a decrease in in-cylinder pressure, and a decrease in the heat release rate as the percentage of ethanol increased.

This paper presents the results of a comparative analysis of co-combustion of diesel and biodiesel fuels with hydrated ethanol. The engine tests were conducted for an on-cylinder natural aspirated compression ignition engine operated at a constant rotational speed of 1500 rpm. Experimental investigations were also conducted to evaluate the effects of using hydrated ethanol as additives to diesel or biodiesel fuels to enhance performance, emission and combustion characteristics of direct injection diesel engines. The test engine powered by a diesel-ethanol blend (DE) was compared to a biodiesel-ethanol (BE) blend, characterized by higher values of IMEP and ITE. In the case of the DE blend, the highest ITE value was obtained for 35% of the ethanol fraction (35%). As for the BE blend, similar ITE values (31%) were obtained over the entire range of the ethanol fuel fraction in the blend. In the case of pure B100 or D100 the ignition delay achieves near the same value equal to 17 deg. The lower unrepeatability of engine cycle obtained for the BE blend combustion did not exceed 10%. The highest NO x emissions were obtained for the DE blend with 30% of the EF fraction (5.5 g/kWh). Emissions of THC and NO x increase up to 35% of the EF fraction in blend.

The paper presents results of co-combustion of diesel-biodiesel-ethanol fuel blend in direct injection Diesel engine. Test was performed at constant rotational speed at three commonly used loads of this engine: 100%, 85%, and 70% of load. During the test hydrated ethanol was used at a concentration of 89% of alcohol. In this study, the ethanol fuel was added to diesel-biodiesel fuel blend with concentrations up to 50% with the increment of 5%. The biodiesel was used as an additive to pre-vent the stratification of ethanol and diesel blends. Thermodynamic parameters of engine were analyzed, and combustion process and exhaust emission were characterized. It turned out that with the increase in engine load is possible to utilize larger ethanol fraction in blend. With the increase of ethanol fuel in blend the in-crease in ignition delay (38.5% for full load) was observed, but burning duration decreased (49% for full load). The ethanol fuel share in blend generally causes the increase in...

The paper presents results of experimental investigation of cocombustion process of biodiesel (B100) blended with oxygenated fuels with 20% in volume. As the alternative fuels ware used hydrated ethanol, methanol, 1-butanol and 2-propanol. It was investigated the influence of used blends on operating parameters of the test engine and exhaust emission (NOx, CO, THC, CO2). It is observed that used blends are characterized by different impact on engine output power and its efficiency. Using biodiesel/alcohol blend it is possible to improve engine efficiency with small drop in indicated mean effective pressure (IMEP). Due to combustion characteristic of biodiesel/alcohol obtained a slightly larger specific NOx emission. It was also observed some differences in combustion phases due to various values of latent heat of evaporation of used alcohols and various oxygen contents. Test results confirmed that the combustion process occurring in the diesel engine powered by blend takes place in a shorter time than in the typical diesel engine.

This investigation was carried out to study the engine-out emissions from a four-stroke, four-cylinder, water-cooled spark ignition (SI) engine with kerosene blended gasoline with different proportions of kerosene ranging from 0-50% by volume in step of 10%. Gaseous exhaust emissions were measured with the aid of pocket gas TM-portable gas analyzer. The experimental results showed that the engine-out emissions increase with increase concentration of kerosene in the blend. The analyses gave increase ranging from 21.7-53% for carbon monoxide (CO), 23.4-57.1% for unburnt hydrocarbon (HC) and 2.4-8.2% for particulate matter (PM). The experiment also showed increase in specific fuel consumption (SFC) for all load conditions ranging form 34-36%. Measures needed to reduce fuel adulteration were suggested. The measures encompass effective monitoring mechanism and enforcement of heavy penalty on sale of adulterated fuels.

In this study, the effects of neutralized waste cooking oil biodiesel-diesel mixture (B30) and diesel fuels on combustion, performance and emission characteristics were investigated and compared experimentally in a four stroke, single cylinder direct injection diesel engine at different engine loads. For this reason the test engine was operated with different engine loads including 3.75, 7.5, 11.25, 15 and 18.75 Nm at 2200 rpm engine speed. The variations of in-cylinder pressure, heat release rate, cyclic variations, combustion duration and CO, CO 2 , NO x and soot emissions were determined. The test results showed that in-cylinder pressure and heat release rate increased with B30 compared to diesel for all engine loads due to better oxidation reactions. CO and soot emissions reduced  by about 57.9 % and 25.5 % with biodiesel compared to diesel at 18.75 Nm. It was also found that higher indicated mean effective pressure (imep) was obtained with B30 according to neat diesel. Besides,...

This paper presents a computer-based air-fuel model of spark-ignition (SI) internal combustion engines. The model can be used to analyse the engine's performance with conventional and alternative fuels. The paper describes the mathematical formulation of the model and outlines the main features of its computer code. The model is verified against published results of earlier fuel-inducted air-fuel models and then used to analyse the performance of a SI engine with ethanol and ethanol-gasoline mixture. The engine's efficiency and indicated mean effective pressure are evaluated at different engine speeds, compression ratios and equivalence ratios.

Alcohol fuels offer opportunities to reduce the use of fossil fuels in CI engines and to increase percentage of biofuels in the transport and energy sectors, where combustion engines are often used. This study presents experimental examinations of a stationary single-cylinder compression ignition dual-fuel engine based on cocombustion of diesel fuel with alcohols. The study evaluated the effect of addition of methanol, ethanol, 2propanol and 1-butanol to diesel fuel on the combustion process, performance and emissions from a research engine. Percentage of the energy supplied in the alcohol fuel was 15, 30, 45, 55 and 70% of total energy supplied with fuel to the engine. The results of the examinations were compared to the examinations for the engine fuelled with pure diesel fuel as a reference. Addition of alcohol to diesel fuel had a positive effect on the level of mean indicated pressure, thermal efficiency and stability of the research engine. The increase in energy percentage of each alcohol to 55% during co-combustion with diesel fuel led to the mean increase in indicated mean effective pressure (IMEP) by 22%, mean increase of indicated thermal efficiency (ITE) by almost 13% and reduction in coefficient of variation COV IMEP by 52%. Of the alcohols analysed in the study, methanol was the most beneficial in terms of high indicated pressure and high efficiency, with maximal values of IMEP = 0.86 MPa and ITE = 35.3% at DM55. Addition and increase in percentage of each alcohol to 55% led to the increase in emissions of nitrogen oxides (by 139% on average), decline of carbon oxide emissions (by 45% on average) and increase in carbon dioxide emissions (by 17% on average). However, it did not lead to significant changes in emissions of hydrocarbons. The highest content of NO x , CO and CO 2 in engine exhaust were found for co-combustion of diesel fuel with addition of methanol.

This paper concerns the development and evaluation of a new and generalised road dust emission model. Most of today's road dust emission models are based on local measurements and/or contain empirical emission factors that are specific for a given road environment. In this study, a more generalised road dust emission model is presented and evaluated. We have based the emissions on road, tyre and brake wear rates and used the mass balance concept to describe the build-up of road dust on the road surface and road shoulder. The model separates the emissions into a direct part and a resuspension part, and treats the road surface and road shoulder as two different sources. We tested the model under idealized conditions as well as on two datasets in and just outside of Oslo in Norway during the studded tyre season. We found that the model reproduced the observed increase in road dust emissions directly after drying of the road surface. The time scale for the build-up of road dust on the road surface is less than an hour for medium to heavy traffic density. The model performs well for temperatures above 0 C and less well during colder periods. Since the model does not yet include salting as an additional mass source, underestimations are evident under dry periods with temperatures around 0 C, under which salting occurs. The model overestimates the measured PM 10 (particulate matter less than 10 mm in diameter) concentrations under heavy precipitation events since the model does not take the amount of precipitation into account. There is a strong sensitivity of the modelled emissions to the road surface conditions and the current parameterisations of the effect of precipitation, runoff and evaporation seem inadequate.

The multifractal relationship between reference evapotranspiration (ET0), computed by the Penmann-Monteith equation (PM), relative humidity (RH) and mean surface temperature (Tmean) was studied in the middle zone of the Guadalquivir River Valley (south Spain) in a previous study. This work extends that study to the average wind speed (U2) and solar radiation (SR), focusing on more recent years. All agro-meteorological variables were analyzed by multifractal detrended cross-correlation analysis (MFCCA) and multifractal detrended fluctuation analysis (MFDFA). The outcomes revealed persistent long-term autocorrelations, with Tmean and RH having the highest persistence (H>0.75). More precise results of multifractal properties than in the previous study were obtained for ET0, Tmean, and RH due to the elimination of trends in the signals. Only medium and large fluctuations in ET0 showed multifractal cross-correlations with its controlling factors, except for U2. Moreover, joint scaling...

Together with renewed legislations, the automotive industry and research centers continue their efforts to develop internal combustion engine (ICE) technologies that consume less fuel and more environmentally. The basic step in developing efficient and environmentally ICEs is to ensure that the parameters affecting the in-cylinder combustion and the exact combustion. Although there are many parameters that affect each other, such as fuel consumption, emissions and noise, the main source of these results is the in-cylinder combustion event. Control of combustion initiation, ignition delay, and combustion must be well understood as all output will affect it. Although many parameters in today's ICE technology such as fuel temperature are controlled by sensors and instantly evaluated with Electronic Control Unit (ECU), optimization of feedback is provided by analyzing the factors affecting ignition delay. The factorial design method is used in this optimization study which examines the parameters of engine speed, load and fuel temperature. In this optimization study, it has been found that the engine speed, load and fuel temperature significantly influence ignition delay in different sizes.

Due to increasingly stringent emission regulations and the need of more efficient powertrains, obtaining information about combustion process becomes a key factor. Low-cost in-cylinder pressure sensors are being developed, but they still present longterm reliability issues, and represent a considerable part of the engine management system cost. Research is being conducted in order to develop methodologies for extracting relevant combustion information using standard sensors already installed on-board. The present work introduces a methodology for combustion parameters estimation, through a control-oriented analysis of structureborne sound. The paper also shows experimental results obtained applying the estimation methodology to different passenger car engines.

Due to increasingly stringent emission regulations and the need of more efficient powertrains, obtaining information about combustion process becomes a key factor. Low-cost in-cylinder pressure sensors are being developed, but they still present longterm reliability issues, and represent a considerable part of the engine management system cost. Research is being conducted in order to develop methodologies for extracting relevant combustion information using standard sensors already installed on-board. The present work introduces a methodology for combustion parameters estimation, through a control-oriented analysis of structureborne sound. The paper also shows experimental results obtained applying the estimation methodology to different passenger car engines.

The complexity of spatial-temporal air pollutant concentration dynamics requires innovative modeling investigation approaches. The details of non-linear nature of pollutant behavior cannot be revealed by conventional approaches, but fractal and Hurst rescaled analyses allow the quantification of pollutant dynamics structure via self-similarity and scale invariance. In this study, we applied multiscale multifractal analysis (MMA) to investigate the complex time-series of criteria air pollutants (PM 10 , PM 2.5 , NO X , SO 2 , CO and O 3). The results showed that PM 10 and PM 2.5 concentrations are more stable compared to gaseous oxides and exhibit less prominent multifractality. Out of gaseous contaminants, CO is confirmed to be less chemically reactive than NO, NO 2 , NO x , SO 2 and O 3 under the same atmospheric conditions in urban and semi-urban area. As concluded, the multifractal analysis presented herein can enhance our understanding of specific pollutant dynamic features and support relevant sectors to control the pollutant release and distribution.

To improve the performance and emission characteristics in the diesel/CNG dual-fuel combustion mode, bio-fuel of n-butanol as the additive in the pilot fuel was investigated by sweeping a wide range of CNG substitution rates. The experiments were conducted at fixed CA50s of 4.5 and 5.5 CA ATDC for approximately 5 bar IMEP (low load) and 7.5 bar IMEP (medium load). At low load, the pilot fuel with nbutanol can shorten the combustion duration for each CNG substitution rate, and D90B10 (90% diesel/ 10% n-butanol by volume basis as the pilot fuel) can improve the indicated thermal efficiency (ITE) with the relatively high CNG substitution rates and reduce CO emission. D80B20 (80% diesel/20% n-butanol by volume basis as the pilot fuel) can reduce both the NO x and CO emissions simultaneously compared to pure diesel as the pilot fuel. At medium load, the pilot fuel with n-butanol can improve ITE with the relatively low CNG substitution rates. It can also reduce the CO emission but slightly increase the NO x emissions. It can be found that the THC emissions are more sensitive to the CNG substitution rate. In addition, the pilot fuel with n-butanol can reduce the CO 2 emission at most CNG substitution rates.

Due to African dust, the Caribbean area is known to have one of the highest incidences of asthma on the planet. Consequently, it is crucial to dissociate the impact of local sources from large scale sources in this region. The aim of this study was to estimate the PM 10 detection threshold for dusty events using a statistical approach and a dynamic approach. To carry out this analysis, PM 10 time series from Martinique (MAR), Guadeloupe (GPE) and Puerto-Rico (PR) were used between 2006 and 2016. The statistical analysis highlighted that the distance from the African coast is a key feature for PM 10 concentrations distribution with the highest at MAR (26.52 μg/m 3) and the lowest at PR (24.42 μg/m 3). The probability density function analysis showed that MAR-GPE-PR distributions converge towards a same point between the first and the second maximum probability value at 28 μg/m 3. The dynamical analysis with the Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) and the Improved CEEMDAN (ICEEMDAN) validated the 28 μg/m 3 found with the statistical analysis. The analysis of HYSPLIT back trajectories confirmed this threshold. Thus, our results indicated that 28 μg/m 3 is the PM 10 detection threshold for African dust in the Caribbean basin. It will therefore be a good indicator allowing the competent authorities to take the appropriate decisions to protect vulnerable populations during dusty events.

Investigation of a new type of fuel for the internal combustion engine, which can be successfully used in both the power generation and the automotive industries, is presented in this article. The proposed fuel is a blend of 75% n-butanol and 25% glycerol. The engine tests conducted with this glycerol–butanol blend were focused on the performance, combustion thermodynamics, and exhaust emissions of a spark-ignition engine. A comparative analysis was performed to find potential similarities and differences in the engine fueled with gasoline 95 and the proposed glycerol–butanol blend. As measured, CO exhaust emissions increased, NOx emissions decreased, and UHC emissions were unchanged for the glycerol–butanol blend when compared to the test with sole gasoline. As regards the engine performance and combustion progress, no significant differences were observed. Exhaust temperature remarkably decreased by 3.4%, which contributed to an increase in the indicated mean effective pressure by...

In this research, three basic macroscopic spray characteristics (spray tip penetration, spray cone angle, and spray area) of long-chain alcohol-biodiesel blends were studied to investigate the differences of macroscopic spray characteristics of long-chain alcohol-biodiesel blends with different mixing ratios and to further investigate the effects of blending long-chain alcohols into biodiesel on the spray characteristics. Two kinds of long-chain alcohols, n-butanol, and n-pentanol, were selected to study effects of difference kinds of long-chain alcohols on macroscopic spray characteristics of long-chain alcohol-biodiesel blends. Results show that with the increase of proportion of n-butanol or n-pentanol in blends, spray tip penetration decreased while spray cone angle and spray area increased; in terms of the effects brought by different long-chain alcohols, n-pentanol-biodiesel blends showed slightly longer spray tip penetration, smaller spray cone angle and smaller spray area co...

Due to increasingly stringent emission regulations and the need of more efficient powertrains, obtaining information about combustion process becomes a key factor. Low-cost in-cylinder pressure sensors are being developed, but they still present longterm reliability issues, and represent a considerable part of the engine management system cost. Research is being conducted in order to develop methodologies for extracting relevant combustion information using standard sensors already installed on-board. The present work introduces a methodology for combustion parameters estimation, through a control-oriented analysis of structureborne sound. The paper also shows experimental results obtained applying the estimation methodology to different passenger car engines.

Since multi-mode engine combustion strategies are being investigated as a pathway to increased vehicle fuel efficiency, a better understanding of particulate matter formation during the advanced compression ignition (ACI) modes and the resulting PM properties are of growing importance for mitigating PM emissions and/or developing emissions control strategies. ACI combustion strategies have demonstrated extremely low engine-out soot while achieving high break thermal efficiencies. However, USregulated emissions for particulate matter (PM) are on a mass basis, which can consist of ash, soot or elemental carbon (EC), and organic carbon (OC). The composition of PM mass from ACI combustion ranges from nearly 100% OC to a mix of EC and OC particulates as the extent of fuel stratification increases. How the mass, compositions, and morphology of PM changes as fuel stratifies within the combustion chamber and what this can tell us about PM formation are presented through multi-cylinder, metal engine experiments. Using ACI modes ranging from homogeneous to highly stratified approaches, this study aimed to advance the understanding of how air-fuel stratification and fuel properties impact PM emissions formation; advanced gaseous and solid emission characterizations are also given. This study is part of a collaborative multi-lab initiative at the US Department of Energy that aims to simultaneously transform both transportation fuels and vehicles in order to maximize performance and energy efficiency, minimize environmental impact, and accelerate widespread adoption of innovative combustion strategies by providing the underlying science for this initiative.

The search for alternative fuels for internal combustion engines is ongoing. Among the alternatives, plant-based fuels can also be mentioned. Alcohol is not a common fuel for diesel engines because the physical and chemical properties of the alcohols are closer to those of gasoline. In our research, the combustion properties of diesel-n-butanol mixtures have been investigated to obtain results on the effect of butanol blending on combustion. Among the combustion properties, ignition delay, in-cylinder pressure, and heat release rate can be mentioned. They have been observed under different compression conditions on an engine on which the compression ratio can be adjusted. The method used was a quite simple one, so the speed of the engine was set to a constant 900 rpm without load, while three compression ratios (19.92, 15.27, and 12.53) were adjusted with a fuel flow rate of 13 mL/min and the pre-injection angle of 18° BTDC. Blending butanol into the investigated fuel does not signi...

Despite the effort done by member states during the last decade, failure in the implementation of the Ambient Air Quality Directive is being continuously registered in many European cities for different air pollutants. One of the biggest concerns in Bulgaria is the exceeded PM10 concentration in the ambient air, measured in all six air quality zones during the winter period. This has induced numerous activities (at the national and European level) focused on the following issues: identification of the level of exceedance of the air quality norms for PM10; the general emission sources; the most prominent omissions and discrepancies in the legislative framework; the level of implementation of the prescribed measures and many others. However, the PM10 exceedance is still of a significant concern in at least 28 municipalities in Bulgaria. Thus, the present work introduces a brief report on the current state of the problem in the country. For that purpose, benchmarking analyses was appli...

A new advanced combustion mode is introduced, called Thermally Stratified Compression Ignition (TSCI), which uses direct water injection to control both the average temperature and the temperature distribution prior to ignition, thereby providing cycle-to-cycle control over the start and rate of heat release in Low Temperature Combustion (LTC). Experiments were conducted to fundamentally understand the effects of water injection on heat release in LTC. The results show that water injection retards the start of combustion due to the latent heat of vaporization of the injected water. Furthermore, for start of water injection timings between 20 and 70 degrees before top dead center, combustion is significantly elongated compared to without water injection. The 10% to 90% burn duration with 6.6 and 9.0 mg of water per cycle was 77% and 146% longer than without water injection, respectively. Direct water injection reduces the heat release rate by local evaporative cooling that results in a forced thermal stratification. Finally, the load limits with and without water injection were determined experimentally. Without water injection, the load range was 2.3 to 3.6 bar gross IMEP. By using water injection to control heat release, the load range in TSCI was 2.3 to 8.4 bar gross IMEP, which is a range expansion of over 350%. These results demonstrate that direct water injection can provide significant improvements to both controllability and the range of operability of LTC, thereby resolving the major challenges associated with HCCI.

This paper presents a numerical study on a group of alternative gaseous fuels – syngases, and their use in the spark-ignition internal combustion engine Lombardini LGW 702. These syngas fuel mixtures consist mainly of hydrogen and carbon monoxide, together with inert gases. An understanding of the impact of the syngas composition on the nature of the combustion process is essential for the improvement of the thermal efficiency of syngas-fuelled engines. The paper focuses on six different syngas mixtures with natural gas as a reference. The introduction of the paper goes through some recent trends in the field of the alternative gaseous fuels, followed by a discussion of the objectives of our work, together with the selection of mixtures. Important part of the paper is dedicated to the experimental and above all to the numerical methods. Two different simulation models are showcased: the single-cylinder ‘closed-volume’ combustion analysis model and the full-scale LGW 702 model; all p...

Changes in rainfall seem to be the main impact of climate change in the Caribbean area. The last conclusions of IPCC (2013), indicate that the end of this century will be marked by a rise of extreme rainfalls in tropical areas, linked with increase of the mean surface temperature. Moreover, most of the Lesser Antilles islands are character-ized by a complex topography which tends to enhance the rainfall from synoptic disturbances by orographic effects. In the past five years, out of hurricanes passage, several extreme rainy events (approx. 16 mm in 6 min-utes), including fatal cases, occurred in the Lesser Antilles Arc: in Guadeloupe. These phenomena inducing floods, loss of life and material damages (agriculture sector and public infrastructures), inhibit the development of the islands. At this time, numerical weather prediction models as WRF, which are based on the equations of the atmospheric physics, do not show great results in the focused area (Bernard et al., 2013). Statistic...

The Mass Fraction Burn (MFB) and Heat Release Rate (HRR) reflect the amount of fuel burned and the rate of burning throughout the combustion process in an internal combustion engine. These parameters play a crucial role in research and development endeavours focused on engine efficiency, emissions, and overall operating performance. Analytically in a Spark-Ignition (SI) engine, these parameters are often modelled with the Wiebe function, a well known mass fraction burn formulation, which is a function of " a " (efficiency parameter), " m " (form factor), crank angle, and the duration of combustion. This function is a simple but powerful correlation model that is well suited for zero and one dimensional engine cycle simulations. In this work, the Wiebe function parameters are determined over a range of fuel compositions and compression ratios by fitting the Wiebe function curve to the experimentally obtained MFB data from a single-zone HRR analysis. The Wiebe func...

The influence of added alcohols, ethanol and butanol, on the main biofuel properties, such as the specific gravity, Reid saturated vapour pressure and distillation curves have been investigated. These properties are intimately related to the fuel composition and their prediction relies on the knowledge of its components characteristics. This research proves the possibility of obtaining fuels with different levels of resistance to detonation, using gasoline with different chemical components and various fractions of alcohols.

The intermittency of the wind turbine power remains an important issue for the massive development of this renewable energy. The power variability of the produced electricity are inherent to the wind variations, thus the turbulence. The energy peaks injected in the electric grid produce a supplementary difficulty in the energy distribution management. Hence, a correct forecast of the wind power in the short and middle term is needed due to the high unpredictability of the intermittency phenomenon. We consider a statistical approach through the analysis and characterization of stochastic fluctuations. The theoretical framework is the multifractal energy cascades. The tools and methods aim to study the influence of the fully developed turbulence on a horizontal three-blade wind turbine. Here, we consider simultaneous input/output data coming from two wind turbines which have a Direct Drive technology. Those turbines are producing energy in real exploitation conditions and allow to tes...

The intermittency of the wind turbine power remains an important issue for the massive development of this renewable energy. The power variability of the produced electricity are inherent to the wind variations, thus the turbulence. The energy peaks injected in the electric grid produce a supplementary difficulty in the energy distribution management. Hence, a correct forecast of the wind power in the short and middle term is needed due to the high unpredictability of the intermittency phenomenon. We consider a statistical approach through the analysis and characterization of stochastic fluctuations. The theoretical framework is the multifractal energy cascades. The tools and methods aim to study the influence of the fully developed turbulence on a horizontal three-blade wind turbine. Here, we consider simultaneous input/output data coming from two wind turbines which have a Direct Drive technology. Those turbines are producing energy in real exploitation conditions and allow to tes...

Several researchers are investigating strategies to lower the emissions and increase the efficiency of combustion engines to reduce the negative impact on the environment and the climate from transportation. The low temperature combustion (LTC) concept is the basis for some of these high-efficiency, low-emission combustion
technologies. To maximize the combustion controllability of engines based on the LTC concept, the combustion behavior of fuel both at different equivalence ratios (ɸ) and under ɸ sweeps must be understood and planned
precisely. The ɸ-sensitivity of a fuel explains its behavior at different engine loads or stratification levels. In this study, a new test method for empirically evaluating ɸ-sensitivity using a Cooperative Fuel Research (CFR) engine
is proposed and the validity of the method is investigated. A modified CFR engine for homogeneous-charge compression ignition (HCCI) combustion is used to investigate the compression ratio (CR) sensitivity of
different toluene–ethanol reference fuels (TERFs) in a research octane number (RON) range of 63–105. This study suggests a method to quantify the ɸ-sensitivity of different fuels and blends by measuring the compression
ratio required to keep the CA50 constant while varying ɸ. It shows that the fuel composition greatly affects the fuel ɸ-sensitivity even for different blends with the same RON. The results also indicate that the coexistence of ethanol and toluene in a blend can generate the highest ɸ-sensitivity of the blend compared to other blends with the same RON. Fuel composition has a strong effect on emissions. The simultaneous effect of fuel composition and ɸ variation on the emission and stability parameters is nonlinear.

Stable HCCI combustion requires a proper level of fuel reactivity. This study shows that adding ethanol as a renewable fraction to low octane gasoline decreases the reactivity of the gasoline, while adding 2-ethyl hexyl nitrate (2-EHN) can enhance the reactivity of the blend and counter the effect of ethanol. The experimental apparatus consisted of a modified CFR engine for HCCI combustion equipped with two port fuel injectors and an intake air heater. Gasoline blended with ethanol (10% v/v) was used as the base fuel. Different percentages of 2-EHN (0.25%, 0.50%, 1%, and 2.5%) were added to the base fuel as an ignition improver. The blends were tested at operating points defined for HCCI number at two different engine speeds (600 and 900 rpm) and three different intake temperatures (50, 100, and 150°C) to investigate the effect of 2-EHN on the auto-ignition behavior of the fuel. Combustion, emissions, and performance parameters of HCCI combustion of the blends were measured. The presence of 2-EHN in the blends improved the auto-ignitability of the blends in a nonlinear manner. It was also found that 0.25% of 2-EHN can compensate for the effect of ethanol on the required compression ratio and remove the quenching effect of ethanol on low temperature heat release. The results show that for the same fuel, a higher compression ratio is needed to maintain the combustion phasing constant at a higher engine speed.

In this work, an investigation of soot-in-oil samples drawn from the oil sump of a gasoline direct injection (GDI) engine was carried out. Soot particulate was characterised in terms of size, distribution and shape of the agglomerates, and internal structure of the primary particles. The test engine was a 1.6 l modern light-duty EURO IV engine operated at speed between 1600 and 3700 rev/min, and torque between 30 and 120 Nm. After a double oil-flushing procedure the engine was operated for 30 h. Oil samples were drawn from the sump and prepared for Transmission Electron Microscopy (TEM) and High resolution TEM analysis (HRTEM) by a combination of solvent extraction, centrifugation and diethyl ether bathing. Soot agglomerates were measured in terms of their skeleton length and width, and fractal dimension. The mean skeleton length and width were 153 nm and 59 nm respectively. The fractal dimension was calculated using an iterative method and the mean value was found to be 1.44. The primary particles were found to be spherical in shape with some irregularities and presented an average diameter of 36 nm with a mode of 32 nm and standard deviation of 13 nm. The majority of particles showed an inner core and outer shell similar to diesel soot, although an amorphous layer was also clearly visible.