Gasoline Evaporation Research Articles

Characteristics and Source Apportionment of VOCs in a City with Complex Pollution in China

ABSTRACT Volatile organic compounds (VOCs) are important precursors in the formation of ozone (O3) and secondary organic aerosol (SOA). Hence, using an online monitor, we measured the concentrations of 56 VOC species in Handan, one of the most polluted cities in China, from Sep. 2017 till Aug. 2018. We also characterized the VOC pollution by measuring the O3 and NOx and determining the chemical reactivity of the VOCs at different levels of O3 pollution, analyzing the regional O3 formation mechanisms, and apportioning the VOC sources. The daily VOC concentrations displayed a wide range, from 37.7 to 288.9 µg m–3, with an average of 112.0 ± 45.5 µg m–3, during the observation period, and the contribution of alkenes and other aromatics to the O3 formation potential (OFP) of the VOCs was higher on medium pollution days than clean days. Furthermore, the majority of the O3 during spring and winter was formed in VOC-sensitive regimes, whereas the high diurnal concentrations during summer and autumn were produced in NOx-sensitive regimes. Based on the i-butane/n-butane and i-propane/n-propane ratios, the main sources of butane and propane were vehicular exhaust and liquid gasoline, respectively. Source apportionment by principal component analysis (PCA) revealed that the VOCs in Handan originated from vehicular emission, industrial production, solvent use, gasoline evaporation, and combustion.

Seasonal variability of VOCs in Nanjing, Yangtze River delta: Implications for emission sources and photochemistry

Online measurements of volatile organic compounds (VOCs) during the entire year of 2016 were conducted at an urban site in Nanjing, Jiangsu Province of China. Seasonal variation characteristics in ambient VOCs levels, ratios, and sources were then analyzed to investigate which factors controlled seasonal cycles of VOCs levels during 2016. Impact of photochemistry was evaluated based on monthly average concentrations of OH radical ([OH]) determined by ratios of ethene versus acetylene and o-xylene versus ethylbenzene. [OH] exhibited higher values during summer and lower values during winter, similar with the seasonality of ozone concentrations and ultraviolet radiation, indicating the existence of photochemical influence on VOCs. Further variance analysis on VOCs levels suggested that seasonality of photochemistry played a minor role in explaining VOCs seasonal cycles. Monthly changes in VOCs sources were then analyzed using the Positive Matrix Factorization (PMF) receptor model. Seven factors were identified, including two factors related to traffic emission and other combustion processes (i.e. vehicular exhaust + combustion processes, gasoline evaporation + vehicular exhaust), two factors related to petrochemical industry (i.e. petrochemical industry#1-propane and petrochemical industry#2-propene), two factors attributed to paints and solvents use (i.e. paints and solvents use#1-toluene, paints and solvents use#2-C8 aromatics), and a factor related to biogenic emission. Gasoline evaporation + vehicular exhaust and biogenic emission both exhibited higher relative contributions during summertime. Meanwhile, relative contributions of petrochemical industry and vehicular exhaust + combustion processes showed maximum during winter and minimum during summer. Relative contributions of two factors related to paints and solvents use showed higher values in March–April and August–September. Conditional probability function (CPF) analysis identified the influence of transport on seasonal changes in VOC source contributions. Finally, the PMF results of this study were compared with recent publications. The discrepancy of VOCs sources reported by different studies implied that there is still large uncertainty in our knowledge on VOCs emissions in Nanjing, and therefore further research on evaluation of VOCs emission inventories and source apportionment is needed in future.

Characteristics and source apportionment of atmospheric volatile organic compounds in Beijing, China.

This paper focused on VOCs and their source apportionment in urban Beijing. Our monitoring measured 52 VOCs in July 2014 and January 2015. The concentration of VOCs was in the range of 14.5~95.2ppb in July and 2.1~93.1ppb in January, with the top five compounds of toluene (10.7%), ethane (6.9%), ethylene (6.3%), n-butane (5.7%), and propane (5.6%) in July and ethylene (14.7%), n-butane (14.2%), ethane (9.6%), propylene (8.0%), toluene (7.9%), and benzene (6.9%) in January. The ratio of VOCs to CO reached 0.059 in July and 0.022 in January on average. These differences implied a potential seasonal difference in the VOC source contribution. Then, we conducted a source apportionment study based on 21 major VOCs and CO by using probabilistic matrix factorization (PMF) receptor model. According to the similarity between the PMF analysis profiles and the known source profiles, combustion sources, petrochemical industry sources, solvent utilization sources, and gasoline evaporation sources were identified. The correlation coefficient (R) between the PMF analysis profile and the source profile reached 0.68~0.87 in July and 0.53~0.92 in January. The better apportionment performance in July was mainly due to the use of intensive VOC observations at a 3-h resolution. When we conducted another PMF source apportionment for July based on 12-h resolved concentration input, the R values decreased to 0.47~0.73. Thus, the PMF model depends heavily on the sample number of concentration inputs, and intensive observation is more propitious. Our PMF apportionment results showed that combustion sources, petrochemical industry, solvent utilization, gasoline evaporation, and other sources contributed ambient VOCs in Beijing urban areas of 13.7ppb, 5.1ppb, 7.7ppb, 12.8ppb, and 3.3ppb in July and 13.2ppb, 2.0ppb, 5.7ppb, 6.6ppb, and 1.0ppb in January, respectively, on a monthly average. These apportionment results match well with the 2013 VOC emission inventory calculated by this study, but also presented significant seasonal differences in the petrochemical industry and gasoline evaporation, in which VOC emissions strongly respond to environmental temperature.

Evaporative volatile organic compounds from gasoline in Mexico City: Characterization and atmospheric reactivity

In 2016, only 4% of energy consumption in transportation came from renewables; then, use of fossil fuels will continue by several decades, with their corresponding evaporative and combustion emissions. Volatile organic compounds (VOCs) from gasoline evaporation were determined in Mexico City in order to know the emission of each compound to the atmosphere, as well as their ozone formation potential. Headspace technique was used to characterize the VOC evaporated mixture from different gasolines consumed in the city. Analyses of VOCs were carried out by chromatography with flame ionization detector. Composition of gasoline vapors was 18.40 ± 4.43 for paraffin, 52.4 ± 2.09 for iso-paraffin, 11.8 ± 3.71 for olefins, 3.1 ± 1.09 for naphthenes, and 12.1 ± 3.23 for aromatics (% w/w), which is quite different of exhaust emissions from gasoline vehicles. The content of carcinogenic VOCs was 0.44 ± 0.07 and 0.02 ± 0.01 (% w/w) for benzene and 1,3-butadiene, respectively, but despite the small content, they should be reduced as much as possible to protect inhabitants health. Despite i-sopentane, methylpentanes, n-pentane, and the sum of trimethylpentanes, had the greater abundance in evaporative emissions, the major contributors to reactivity were the olefins contributing with 62% for the potential ozone formation, estimated with the maximum incremental reactivity.

Improvements in a kinetic-based model to predict evaporation of gasoline

Reference collections containing chromatograms of ignitable liquids are widely used in fire debris analysis to aid the identification of any liquid present in the debris. Most reference collections also include chromatograms of ignitable liquids evaporated to different levels to account for chemical changes as a result of evaporation during the fire. Previous work in our laboratory demonstrated the potential of a kinetic-based model to predict chromatograms corresponding to evaporated liquids, thereby eliminating the need for experimental evaporations. Our initial work indicated the need to improve accuracy in predicting chromatograms corresponding to evaporated gasoline, which is the focus in the current work.Three gasoline samples were experimentally evaporated to 50%, 70%, and 90% by mass and analyzed by gas chromatography-mass spectrometry (GC–MS). Modifications to the instrument method, including elimination of the solvent delay and subtraction of background interferences, resulted in improved correlation between predicted and experimental chromatograms at each evaporation level. Modification of the method used to calculate the total fraction of the liquid remaining offered further improvement in predictive accuracy across all three evaporation levels. Application of the model to generate a reference collection of predicted chromatograms for gasoline and other ignitable liquids was also demonstrated, with maximum Pearson product-moment correlation (PPMC) coefficients ranging from 0.937 to 0.991 for comparisons of predicted and experimental gasoline. The model improvements reported here provide a method by which predicted chromatograms corresponding to any evaporation level of gasoline can be generated accurately, saving time and resources in generating reference collections for fire debris applications.

Impact of ethanol blending into gasoline on aromatic compound evaporation and particle emissions from a gasoline direct injection engine

This study examined the interactions of ethanol with aromatic compounds on aromatic species evolution during gasoline evaporation and the consequent impacts on particle emissions from a single-cylinder, gasoline direct injection engine. From a chemical kinetic standpoint, the dilution of the aromatic species in gasoline by ethanol blending should reduce particle emissions because aromatics are the primary species that form particles during gasoline combustion. However, increased evaporative cooling from the ethanol and ethanol’s effect on when aromatics in the fuel droplet (or surface film or pool) evaporate can drive an increase in particle emissions. The objective of this study was to quantify these competing effects. The results show that a combination of ethanol’s increased evaporative cooling and impact on aromatic compound vapor-liquid equilibrium can extend droplet lifetime and cause aromatics to evaporate later in the droplet evaporation process than would be the case without ethanol. When fuels were burned in a direct-injection single-cylinder engine at high speed (2500 rpm) and relatively high load, ethanol blending caused an increase in particle emissions for fuels containing a low vapor pressure aromatic. At a lower speed (1500 rpm), no statistically significant increase in particle emissions was observed, likely because more time was available for evaporation and mixing to occur. In contrast, particle emissions from a fuel blended with a high vapor pressure aromatic were either insensitive to or reduced by ethanol blending, likewise to engine operating conditions. Current models for predicting particle emissions from gasoline engines, such as particulate matter index (PMI), generally lack variables for non-linear interactions between ethanol and gasoline hydrocarbons. To identify nonlinear interactions between predictor variables that might better explain the observed particle emissions, the least absolute shrinkage and selection operator (LASSO) regularized regression approach was employed. Among the predictor variables evaluated was the Yield Sooting Index (YSI) which is as an improved measure to quantify the aromatic’s chemical tendency to generate particle emissions. Following this analysis, two variables were selected based on their frequent appearance. The first was ethanol mole percent multiplied by aromatic mole percent divided by aromatic vapor pressure [(EtOH% * Aro%)/Aro VP@443 K]. The second was aromatic mole percent multiplied by aromatic YSI divided by aromatic molecular weight [(Aro% * Aro YSI)/Aro MW]. The results of linear regression including only these two combined explanatory variables achieved an r2 = 0.959, substantially improved over the PMI model (r2 = 0.688) and provides insight into how the PMI formalism might be modified to account for non-linear oxygenate-hydrocarbon coupling.

Investigation of emission characteristics of NMVOCs over urban site of western India

This is the first study to characterize the variation and emission of C2-C5 non-methane volatile organic compounds (NMVOCs) in a semi-urban site of western India based on measurements during February–December 2015. Anthropogenic NMVOCs show clear seasonal dependence with highest in winter and lowest in monsoon season. Biogenic NMVOCs likes isoprene show highest mixing ratios in the pre-monsoon season. The diurnal variation of NMVOC species can be described by elevated values from night till morning and lower values in the afternoon hours. The elevated levels of NMVOCs during night and early morning hours were caused mainly by weaker winds, temperature inversion and reduced chemical loss. The correlations between NMVOCs, CO and NOx indicate the dominant role of various local emission sources. Use and leakage of liquefied petroleum gas (LPG) contributed to the elevated levels of propane and butanes. Mixing ratios of ethylene, propylene, CO, NOx, etc. show predominant emissions from combustion of fuels in automobiles and industries. The Positive Matrix Factorization (PMF) source apportionments were performed for the seven major emission sectors (i.e. Vehicular exhaust, Mixed industrial emissions, Biomass/Fired brick kilns/Bio-fuel, Petrochem, LPG, Gas evaporation, Biogenic). Emissions from vehicle exhaust and industry-related sources contributed to about 19% and 40% of the NMVOCs, respectively. And the rest (41%) was attributed to the emissions from biogenic sources, LPG, gasoline evaporation and biomass burning. Diurnal and seasonal variations of NMVOCs were controlled by local emissions, meteorology, OH concentrations, long-range transport and planetary boundary layer height. This study provides a good reference for framing environmental policies to improve the air quality in western region of India.

Experimental Comparative Study on Performance and Emissions of E85 Adopting Different Injection Approaches in a Turbocharged PFI SI Engine

This study examines the effects of ethanol and gasoline injection mode on the combustion performance and exhaust emissions of a twin cylinder port fuel injection (PFI) spark ignition (SI) engine. Generally, when using gasoline–ethanol blends, alcohol and gasoline are externally mixed with a specified blending ratio. In this activity, ethanol and gasoline were supplied into the intake manifold into two different ways: through two separated low pressure fuel injection systems (Dual-Fuel, DF) and in a blend (mix). The ratio between ethanol and gasoline was fixed at 0.85 by volume (E85). The initial reference conditions were set running the engine with full gasoline at the knock limited spark advance boundary, according to the standard engine calibration. Then E85 was injected and a spark timing sweep was carried out at rich, stoichiometric, and lean conditions. Engine performance and gaseous and particle exhaust emissions were measured. Adding ethanol could remove over-fueling with an increase in thermal efficiency without engine load penalties. Both ethanol and charge leaning resulted in a lowering of CO, HC, and PN emissions. DF injection promoted a faster evaporation of gasoline than in blend, shortening the combustion duration with a slight increase in THC and PN emissions compared to the mix mode.

Intercomparison of O<sub>3</sub> formation and radical chemistry in the past decade at a suburban site in Hong Kong

Abstract. Hong Kong, as one of the densely populated metropolises in East Asia, has been suffering from severe photochemical smog in the past decades, though the observed nitrogen oxides (NOx) and total volatile organic compounds (TVOCs) were significantly reduced. This study, based on the observation data in the autumns of 2007, 2013 and 2016, investigated the photochemical ozone (O3) formation and radical chemistry during the three sampling periods in Hong Kong with the aid of a photochemical box model incorporating the Master Chemical Mechanism (PBM–MCM). While the simulated locally produced O3 remained unchanged (p=0.73) from 2007 to 2013, the observed O3 increased (p < 0.05) at a rate of 1.78 ppbv yr−1 driven by the rise in regionally transported O3 (1.77±0.04 ppbv yr−1). Both the observed and locally produced O3 decreased (p < 0.05) from the VOC sampling days in 2013 to those in 2016 at a rate of -5.31±0.07 and -5.52±0.05 ppbv yr−1, respectively. However, a leveling-off (p=0.32) was simulated for the regionally transported O3 during 2013–2016. The mitigation of autumn O3 pollution in this region was further confirmed by the continuous monitoring data, which have never been reported. Benefiting from the air pollution control measures taken in Hong Kong, the local O3 production rate decreased remarkably (p < 0.05) from 2007 to 2016, along with the lowering of the recycling rate of the hydroxyl radical (OH). Specifically, VOCs emitted from the source of liquefied petroleum gas (LPG) usage and gasoline evaporation decreased in this decade at a rate of -2.61±0.03 ppbv yr−1, leading to a reduction of the O3 production rate from 0.51±0.11 ppbv h−1 in 2007 to 0.10±0.02 ppbv h−1 in 2016. In addition, solvent usage made decreasing contributions to both VOCs (rate =-2.29±0.03 ppbv yr−1) and local O3 production rate (1.22±0.17 and 0.14±0.05 ppbv h−1 in 2007 and 2016, respectively) in the same period. All the rates reported here were for the VOC sampling days in the three sampling campaigns. It is noteworthy that meteorological changes also play important roles in the inter-annual variations in the observed O3 and the simulated O3 production rates. Evaluations with more data in longer periods are therefore recommended. The analyses on the decadal changes of the local and regional photochemistry in Hong Kong in this study may be a reference for combating China's nationwide O3 pollution in near future.

Photochemical evolution of continental air masses and their influence on ozone formation over the South China Sea

To investigate photochemical ozone (O3) pollution over the South China Sea (SCS), an intensive sampling campaign was conducted from August to November simultaneously at a continental site (Tung Chung, TC) and a marine site (Wan Shan Island, WSI). It was found that when continental air masses intruded the SCS, O3 episodes often occurred subsequently. To discover the causes, a photochemical trajectory model (PTM) coupled with the near-explicit Master Chemical Mechanism (MCM) was adopted, and the photochemical processes of air masses during the transport from TC to WSI were investigated. The simulated O3 and its precursors (i.e. NOx and VOCs) showed a reasonably good agreement with the observations at both TC and WSI, indicating that the PTM was capable of simulating O3 formation for air masses traveling from TC to WSI. The modeling results revealed that during the transport of air masses from TC to WSI, both VOC and NOx decreased in the morning while O3 increased significantly, mainly due to rapid chemical reactions with elevated radicals over the SCS. The elevated radicals over the SCS were attributable to the fact that higher NOx at TC consumed more radicals, whereas the concentration of radicals increased from TC to WSI because of NOx dilution and destruction. Subsequently, the photochemical cycling of radicals accelerated, leading to high O3 mixing ratios over the SCS.Furthermore, based on the source profiles of the emission inventory used, the contributions of six sources, i.e. gasoline vehicle exhaust, diesel vehicle exhaust, gasoline evaporation and LPG usage, solvent usage, biomass and coal burning, and biogenic emissions, to maritime O3 formation were evaluated. The results suggested that gasoline vehicles exhaust and solvent usage largely contributed the O3 formation over the SCS (about 5.2 and 3.8 ppbv, respectively). This is the first time that the contribution of continental VOC sources to the maritime O3 formation was quantified.

Temperature dependence and source apportionment of volatile organic compounds (VOCs) at an urban site on the north China plain

Volatile organic compounds (VOCs) are largely affected by ambient temperature. However, responses of source-specific VOCs to ambient temperature are poorly understood. Based on one-year (2016.4–2017.3) observations for 57 VOC species (average: 33.4 ± 26 ppbv), and on the use of a k-means cluster technique and positive matrix factorization model, temperature dependence of VOCs and their potential sources were studied. The VOC reactivity was dominated by alkenes, though alkanes contributed the most to the VOCs both by volume and by carbon atoms. The cluster analysis suggested that real-world VOCs were influenced directly and indirectly by temperature. The responses of the VOCs in terms of volume and carbon atoms to temperature exhibited V-shape patterns, and the inflection points occurred when temperatures were around 15∼25∘C. Nevertheless, the VOC reactivity generally increased with increasing temperature, suggesting that temperature could be used as a proxy for VOC reactivity. The source apportionment study revealed that vehicle emissions (44.8%) contributed the most to ambient VOCs, and followed by natural gas (NG)/liquefied petroleum gas (LPG)/Combustion (24.9%), petrochemical industry (9.6%), other industrial process (8.4%), solvent use (7.4%), and biogenic emission (4.9%). Solvent use and biogenic emissions were the greatest contributors to VOC reactivity. Unexpectedly high propane/ethylene ratios were observed at low temperatures. This might be associated with domestic heating-related emissions from NG/LPG sources because their contributions generally increased with the decreasing temperature. By comparison with ∼25 ∘C, the VOC concentrations and ozone formation potentials contributed by vehicles were respectively 7- and 2.6- times greater at ∼0 ∘C (cold engine starts dominance), and were 50.4% and 57.5% greater at ∼35 ∘C (gasoline evaporation dominance). Local emission controls for VOCs were beneficial for alleviating atmospheric secondary pollution because the potential source-areas of VOCs were mostly distributed in the geographically flat North China Plain. However, alkanes-dominated VOC sources (e.g., vehicle emission, NG/LPG) could experience long-distance air transport bacause of their relatively long atmospheric lifetime. The results highlight that the temperature dependences of VOCs depend on the emission sources, and this is of great value in understanding the linkage between meteorology and air quality.

Evaporation and mixture formation of gasoline–ethanol sprays in spark ignition engines with pre‐blended injection and dual injection: a comparative study

Evaporation of sprays and mixture formation as injection of pre-blended gasoline–ethanol mixture and as separate injection of the fuels are investigated by means of numerical simulation. Effects of operating conditions and different configurations of injection systems have been examined. Under the same operating conditions, pure gasoline mostly evaporated during the injection period, while pure ethanol evaporated mainly during the compression process. Charge temperature in the cylinder for pure ethanol is ∼60°C lower than that for pure gasoline at the end of the compression process. Independently from injection system, the dual injection results in a higher evaporation rate compared to pre-blended injection. Whether pre-blended injection or dual injection is employed, the evaporation rate is improved for port injection (PI) compared to direct injection (DI). Besides, vapour concentration at the end of the compression process of PI increases with a shift from a single-inlet manifold to double-inlet manifolds. Mixture homogeneity is enhanced with increasing ambience temperature or/and an increasing engine speed with pre-blended injection, while a strong stratified charge mixture is achieved with dual injection using double-inlet manifolds or with DI of ethanol combined with PI of gasoline.

Important role of aromatic hydrocarbons in SOA formation from unburned gasoline vapor

Gasoline emissions are the largest source of urban atmospheric VOCs, which are critical precursors of ozone (O3) and secondary organic aerosol (SOA). Besides vehicle exhaust, emissions from gasoline evaporation also have a potentially significant effect on SOA formation. However, there are still few studies on the relationship between gasoline vapor composition and SOA formation, especially for gasoline in China. In this study, SOA formation from three unburned gasoline vapors were investigated in a 30 m3 indoor smog chamber. The experimental results showed that with the increase of aromatic content (especially toluene and C2 benzenes) in gasoline from 23% to 50%, the SOA yield was significantly enhanced by a factor of 4.0–6.7. This phenomenon might be related to the higher amounts of intermediate volatility organic compounds (IVOCs) and semi-volatile organic compounds (SVOCs) formed, which promoted the gas-particle partitioning and SOA formation. Additionally, the synergistic effects between precursors in the mixtures might also be a key factor, which could be supported by the higher SOA yield accompanied by a higher ratio of toluene/benzene. Meanwhile, there were more oxygenated organic aerosols (OOA) observed when using high-aromatic gasoline. This work will help in understanding the effect of aromatic content or gasoline quality on the SOA formation from gasoline evaporation emissions, and in providing the scientific basis for taking corresponding control measures to relieve haze events in China.

Revealing Benzene, Toluene, Ethyl Benzene, Xylenes (BTEX) Emission at Gas Stations, Case Study in Semarang City

Evaporation of gasoline at gas stations is the origin of air pollutants in gas station environment. This study is intended to estimate BTEX emission levels at gas stations and mapping BTEX emissions at all gas stations in Semarang. 4.09 D Tank Program with supported data collected by survey and secondary data used to calculate the estimated emissions. We also measured BTEX levels in the gas station location sample with charcoal tubes as adsorbent and PCXR4 mini pump sampler. The emissions from dispensers and storage tanks in gas stations have different emission characteristics. The amount of emissions from dispensers for VOC pollutants is 3.9261 tons/year and benzene is 0.0561 tons/year (case study UNDIP gas station). While the emission from a storage tank for VOC pollutants was 232.91 tons/year, benzene was 1.79 tons/year, toluene was 33.36 tons/year, ethylbenzene was 0.39 tons/year, and xylene was 1.43 Tons/year. The estimation results of the model with the results of direct BTEX measurements in the field showed that the field measurement results were smaller than those estimated. Some assumptions used in the calculations contribute to estimating uncertainty. The measured BTEX concentration still meets the quality standard (Minister of Manpower and Transmigration Regulation No. 13 of 2011).

Spatial and temporal variability of BTEX in Paris megacity: Two-wheelers as a major driver

Abstract Besides their impacts on health, BTEX play an important role in the formation of secondary organic aerosols and ozone for which limit values are regularly exceeded in Paris megacity and Ile de France region. An enrichment by a factor of 3 in the C7 C9 aromatic fraction in the Paris atmosphere compared to other northern mid-latitude cities was shown in 2013. Here, we combined different approaches to investigate the role of transport-related sources in such enrichment (gasoline composition and vehicle fleet composition): a statistical analysis of a large BTEX dataset including multi-year and multi-site measurements (traffic, background, tunnel) and a coupled experimental and modelling analysis of liquid and headspace composition of representative fuels distributed in Ile de France region (SP95, SP95 E10, and SP98). For the latter the experimental set-up was designed to analyze the composition of 87 VOCs from C2 to C17 in both liquid and headspace phases. The model is able to predict the headspace composition at ± 15% and with an R2 > 0.9. First a strong positive spatial gradient in BTEX composition at traffic stations is observed, with higher TEX-to-benzene ratio in Paris center compared to the suburbs and outskirts up to a factor of 2. This gradient reflects differences in fleet composition especially gasoline powered vehicles in Paris with a larger proportion of two-wheelers (15% in 2012). This gradient is also consistent with the inter-annual increase of TEX-to-benzene ratios along with the doubling of two-wheelers use and the decrease in the number of passenger cars. The gasoline evaporation model cannot solely explain the observed spatial variability. Finally, we investigated the potential contribution of two-wheelers to the aromatic enrichment in IdF region by introducing an additional unburned gasoline term to the model. The results support the suggestion that two-wheelers are a potential contributor to this enrichment. Considering the high use of two-wheelers in other European cities such as London or Barcelona if Europe is to decrease transport-related air pollution and inner city traffic, policy makers should consider finding alternatives to the conventionally-powered two-wheelers and supporting electric two-wheelers for example.

Design Optimization of an Automotive Fuel Tank for the Minimization of Evaporative Losses of Gasoline Due to Thermal Conduction: Experimental & Analytical Approach

Environment is being polluted due to several toxic gases like CO, CO2, NOx, and HC every day. The sectors responsible for disturbing the balance of atmosphere are mainly industrial and transportation. CO mainly evolved because of lack of oxygen during combustion, NOx evolve if combustion occurs at high temperature and HC released to the atmosphere from exhaust and evaporation of fuel from the fuel tank. Data collection and analysis revealed that the total evaporation loss is around 6 to 7 %. In this paper, an experiment was performed on a two-wheeler tank, which is made of carbon steel sheet metal. Carbon steel sheet metal is one of the major cause of gasoline evaporation due to its high thermal conductivity. In the experiment, evaporative losses of gasoline is quantified along with the heat transfer analysis on the fuel tank body. Experimental results revealed that evaporative loss in C-steel tank is 15.92% and in composite tank with insulated layer is 0.44%. Therefore, the obtained results must have a positive impact on environment i.e. low HC emission into the environment.

Characteristics and Source Apportionment of Summertime Volatile Organic Compounds in a Fast Developing City in the Yangtze River Delta, China

Volatile organic compounds (VOCs) are crucial for ozone formation in the Yangtze River Delta (YRD) in China. The characteristics of ambient VOCs in Nantong, a fast developing city in the YRD, were studied. Sixty ambient air samples were taken at five sites in three sampling days during summer time. One hundred and five VOCs were measured, showing that VOC concentration varied between 27.5 ppbv to 33.1 ppbv at five sites; these levels were generally lower than those for some big Chinese cities like Beijing, Shanghai and Nanjing. With larger fractions of alkanes, the Zilang (ZL) and Sanqu (SQ) sites had relatively higher VOC concentrations among the five sites. The oxidation formation potential (OFP) and secondary aerosol formation potential (SOAFP) were estimated to be 125 μg/m3 and 0.76 μg/m3, respectively. These two values were smaller than those in other big cities, as they were dominated by aromatic compounds (e.g., toluene and benzene) of which concentrations in Nantong were found to be lower. The highest toluene concentration was measured in ZL, implying substantial effects of surface coating industry near the site. Through the Positive Matrix Factorization (PMF) model, the identified sources of VOCs included LPG (Liquefied petroleum gas) combustion (13.9%), chemical industry (8.5%), natural gas use (15.6%), gasoline evaporation (12.8%), petrol industry use (11.8%), solvent use (16.2%) vehicle exhausts (12.1%) and surface coating (9.2%). A relatively small contribution from vehicles was found in Nantong compared with other big cities. Moreover, LPG emissions were identified to be relatively important in Nantong, indicated by the large mass fraction of propane and ethane concentrations in the atmosphere.

SOURCE APPORTIONMENT OF VOCS BY RECEPTOR MODELLING IN AN URBAN SITE IN HA NOI

Volatile organic compounds (VOCs) are atmospheric pollutants of concern because of the health effect including carcinogenic risk of some of their species and the contribution in the formation of tropospheric ozone. The levels of VOCs in Hanoi were demonstrated to be higher than neighboring countries by previous research. The ozone potential formation (OFP) of VOCs was also some folds higher than others. Among transportation sources, VOCs were proved to be mainly emitted from motorbikes. The contribution percentages of transportation and other sources such as industrial, biomass burning sources are still remained unknown. In this research we applied chemical mass balance (CMB) receptor modelling to determine VOCs source apportionment. One week VOCs observation data at Hanoi University of Science and Technology in June 2017 was applied for investigation. Fourteen VOC species among 55 of which were applied for CMB modelling. Transportation and biomass burning source profiles were developed by monitoring in this study. Four other source profiles, namely gasoline evaporation, industrial production, cooking and paint that were compiled or calculated from previous studies. The results showed that the main sources of VOCs were vehicular emission, biomass burning, and gasoline evaporation contributing 37 %, 21 % and 20 % for VOCs levels, respectively. Other sources contributed for the leftover. The results can support to initiate policy for future control of VOCs.

Sources Profiles of Volatile Organic Compounds (VOCs) Measured in a Typical Industrial Process in Wuhan, Central China

Industrial emission is an important source of ambient volatile organic compounds (VOCs) in Wuhan City, Hubei Province, China. We collected 53 VOC samples from petrochemical, surface coating, electronic manufacturing, and gasoline evaporation using stainless canisters to develop localized source profiles. Concentrations of 86 VOC species, including hydrocarbons, halocarbons, and oxygenated VOCs, were quantified by a gas chromatography–flame ionization detection/mass spectrometry system. Alkanes were the major constituents observed in the source profile from the petrochemical industry. Aromatics (79.5~81.4%) were the largest group in auto-painting factories, while oxygenated VOCs (82.0%) and heavy alkanes (68.7%) were dominant in gravure printing and offset printing factories, respectively. Acetone was the largest contributor and the most frequently monitored species in printed circuit board (PCB) manufacturing, while VOC species emitted from integrated chip (IC) were characterized by high contents of isopropanol (56.4–98.3%) and acetone (30.8%). Chemical compositions from vapor of gasoline 92#, 93#, and 98# were almost identical. Alkanes were the dominant VOC group, with i-pentane being the most abundant species (31.4–37.7%), followed by n-butane and n-pentane. However, high loadings of heavier alkanes were observed in the profile of diesel evaporation.

Ozone formation and key VOCs in typical Chinese city clusters

China, especially Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), Pearl River Delta (PRD), and Sichuan Basin (SCB), suffers from severe ozone pollution problems during summer and autumn. Ground-level ozone is formed via a series of complex photochemical reactions between nitrogen oxides (NO x ) and volatile organic compounds (VOCs), which are one of the most concerning pollutants in the four megacities and have adverse impacts on human health. In recent years, O3 concentrations that exceed the national ambient air quality standard have been frequently observed during summer and autumn. However, the mechanism of O3 formation and the key factors that regulate this mechanism have not been studied in detail. To evaluate ozone pollution episodes in Chinese megacities, field observation data of O3 and its precursors at 20 sites in the four major urban regions during summer and autumn from 2014 to 2016 were collected in this study. We found that all the four regions suffered from serious O3 pollution. The daily maximum 8-hour average O3 concentrations ranged from 59–146 (10−9 V/V). Moreover, the hourly maximum O3 concentrations were in the range of 73–187 (10−9 V/V). High values of both these parameters were measured at the same site, Dingling, which is a rural area of Beijing. Furthermore, O3 concentrations in urban areas were lower than those in suburban regions. Ozone non-attainment days occurred more frequently in BTH and YRD than in the other regions. Although the concentrations of NO x and VOCs, which are ozone precursors, varied largely across different sites, they were generally in ranges of ~4–22 (10−9 V/V) and 11–53 (10−9 V/V), respectively. Additionally, isoprene reactivity significantly contributed to total the VOC reactivity ( k VOC) in rural sites. However, in urban sites, the reactivities of alkenes and aromatics were significant contributors. To evaluate the effectiveness of various ozone precursor control strategies in reducing ozone pollution, we combined the observation-based model (OBM) with the relative incremental reactivity (RIR) method. The sensitivity of O3 production was studied by varying the emission of ozone precursors at each site and the key indicators that affect the local ozone production rate were identified. The ozone precursors were divided into four groups: anthropogenic hydrocarbons (AHC), which consist of alkanes, alkenes, and aromatics, natural hydrocarbons (NHC, only isoprene), NO x , and CO. It was found that most of the sites in these four regions were in a VOC-limited regime or transition regime (VOC and NO x sensitive) and the key VOC precursors were alkenes and aromatics. Additionally, an empirical kinetic modeling approach (EKMA) was used to determine the cooperative control scheme for NO x and VOCs. Most of the urban sites were under VOC-limited conditions while the suburban site was in a NO x -limited regime. These results are consistent with the results derived with the RIR method. To further explore the role of anthropogenic emissions in ozone pollution, we used the positive matrix factorization (PMF) model to identify the major sources contributing to VOCs. This model identified five to seven VOCs sources in different urban sites. The major sources for these sites were vehicular exhaust and gasoline evaporation, accounting for 30%–50% of the observed VOCs. According to the source profile, a series of sensitivity tests were performed by reducing each source by 20% to determine the RIR of the individual source. Vehicular exhaust and solvent utilization were the major contributors to O3 formation in Dongsi, Pudong, Modiesha, and Chaozhan, which are located in BTH, YRD, PRD, and SCB, respectively. In summary, by regulating VOCs emissions, especially vehicular emissions and emissions from solvent use, the O3 concentration in China can be efficiently regulated.