Emission Factors Of Hydrocarbons Research Articles

Trace gas emissions from laboratory combustion of leaves typically consumed in forest fires in Southwest China

Forest fires are becoming increasingly severe and frequent due to global climate change. Trace gases emitted from forest fires significantly affect atmospheric chemistry and climate change on a regional and global scale. Forest fires occur frequently in Southwest China, but systematic studies on trace gas emissions from forest fires in Southwest China are rare. Leaves of seven typical vegetation fuels based on their prominence in forest fires consumption in Southwest China were burned in a self-designed combustion device and the emission factors of eighteen trace gases (greenhouse gases, non-methane organic gases, nitrogenous gases, hydrogen chloride, and sulfur dioxide) at specific combustion stages (flaming and smoldering) were determined by using Fourier transform infrared spectroscopy, respectively. The emission factors data presented were compared with previous studies and can aid in the construction of an emission inventory. Pine needle combustion released a greater amount of methane in the smoldering stage than other broadleaf combustion. Peak values of emission factors for methane and non-methane organic gas are emitted by the smoldering of vegetation (Pinus kesiya and Pinus yunnanensis), which is endemic to forest fires in Southwest China. The emission factor for oxygenated volatile organic compounds (OVOCs) in the smoldering stage is greater than the flaming stage. This work established the relationship between modified combustion efficiency (MCE) with emission factors of hydrocarbons (except acetylene) and OVOCs. The results show that exponential fitting is more suitable than linear fitting for the seven leaf fuels (four broadleaf and three coniferous). However, the emission factors from the combustion of three coniferous fuels relative to all fuels are linear with MCE. Findings demonstrated that different combustion stages and fuel types have significant impacts on the emission factors, which also highlighted the importance of studying regional emissions.

Gas and particle phase polycyclic aromatic hydrocarbon emission factors from a diesel vehicle engine: Effect of operating modes in a developing country context

Airborne polycyclic aromatic hydrocarbons (PAHs) arising from diesel exhaust emissions are of concern due to their significant human health and environmental impacts. Engine dynamometer experiments with a light duty diesel engine were conducted to measure PAH emissions representative of developing country conditions, and thereby determine emission factors at two different engine operating modes that are representative of idling and severe real-world conditions, respectively. We employed a portable denuder device for the simultaneous sampling of gaseous and particulate PAH emissions, the components of which were subsequently individually thermally desorbed and analysed by two-dimensional gas chromatography with time-of-flight mass spectrometric detection (TD-GCxGC-ToF-MS). Results indicated that PAH emission factors differed significantly for the different modes of engine operation with the highest emission factor being for idle mode with a total PAH emission factor of 1181.14 μg/kg. Under real-world conditions, it is expected that further variance in emission factors will be introduced as a result of brake and tyre wear, different engine technologies, engine age and maintenance, as well as fuel quality and measurement methods. • A portable denuder sampled gas and particles phase PAHs simultaneously. • Emission factors differ significantly for different engine operation modes. • Idle mode showed higher emission factors than maximum power mode. • PAHs in the exhaust emissions were predominantly found in the gas phase.

Effects of Oil Drops and the Charcoal’s Proximate Composition on the Air Pollution Emitted from Charcoal Barbecues

ABSTRACT This research investigated the emission rates (ERs) and emission factors (EFs) of air pollutants generated from charcoal barbecues and the influence of temperature, the charcoal’s proximate composition (moisture, volatile matter, fixed carbon, and ash), and oil drops. Charcoal briquettes, longan charcoal, and binchotan (commonly used for indoor barbecues) were selected for combustion experiments, and the exhaust gas was collected for the analysis of air pollutants, viz., CO, CO2, NOx, hydrocarbons (HCs), benzene, toluene, formaldehyde, acetaldehyde, PM2.5, and trace metals (Al, Cr, Cu, Fe, and Zn). A linear regression model was employed to verify the major factors affecting the EFs. The EFs of HCs measured during the dripping of oil and sauce on the charcoal ranged from 2486.2 to 9305.2 mg kg–1, 76.4–357% higher than those measured during no dripping. For PM2.5, the EFs measured during dripping ranged from 3080.4 to 3926.5 mg kg–1, 8–19 times higher than those measured during no dripping. The EFs of benzene, toluene, formaldehyde, and acetaldehyde also significantly increased during dripping. In addition, increasing the combustion temperature reduced the EFs of HCs, formaldehyde, and CO but increased those of Fe and Zn. The charcoal moisture content was significantly positively correlated with the EF of HCs, whereas the volatile matter content was significantly positively correlated with those of HCs and benzene. Positive correlations existed between the charcoal ash content and the EFs of CO, Fe, and Zn. The fixed carbon content was significantly positively correlated with the EF of CO2 but negatively correlated with those of CO, Al, and Zn.

Gas-phase composition and secondary organic aerosol formation from standard and particle filter-retrofitted gasoline direct injection vehicles investigated in a batch and flow reactor

Abstract. Gasoline direct injection (GDI) vehicles have recently been identified as a significant source of carbonaceous aerosol, of both primary and secondary origin. Here we investigated primary emissions and secondary organic aerosol (SOA) from four GDI vehicles, two of which were also retrofitted with a prototype gasoline particulate filter (GPF). We studied two driving test cycles under cold- and hot-engine conditions. Emissions were characterized by proton transfer reaction time-of-flight mass spectrometry (gaseous non-methane organic compounds, NMOCs), aerosol mass spectrometry (sub-micron non-refractory particles) and light attenuation measurements (equivalent black carbon (eBC) determination using Aethalometers) together with supporting instrumentation. Atmospheric processing was simulated using the PSI mobile smog chamber (SC) and the potential aerosol mass oxidation flow reactor (OFR). Overall, primary and secondary particulate matter (PM) and NMOC emissions were dominated by the engine cold start, i.e., before thermal activation of the catalytic after-treatment system. Trends in the SOA oxygen to carbon ratio (O : C) for OFR and SC were related to different OH exposures, but divergences in the H : C remained unexplained. SOA yields agreed within experimental variability between the two systems, with a tendency for higher values in the OFR than in the SC (or, vice versa, lower values in the SC). A few aromatic compounds dominated the NMOC emissions, primarily benzene, toluene, xylene isomers/ethylbenzene and C3-benzene. A significant fraction of the SOA was explained by those compounds, based on comparison of effective SOA yield curves with those of toluene, o-xylene and 1,2,4-trimethylbenzene determined in our OFR, as well as others from literature. Remaining discrepancies, which were smaller in the SC and larger in the OFR, were up to a factor of 2 and may have resulted from diverse reasons including unaccounted precursors and matrix effects. GPF retrofitting significantly reduced primary PM through removal of refractory eBC and partially removed the minor POA fraction. At cold-started conditions it did not affect hydrocarbon emission factors, relative chemical composition of NMOCs or SOA formation, and likewise SOA yields and bulk composition remained unaffected. GPF-induced effects at hot-engine conditions deserve attention in further studies.

Emission factors of air pollutants from CNG-gasoline bi-fuel vehicles: Part II. CO, HC and NOx

The estimation of emission factors (EFs) is the basis of accurate emission inventory. However, the EFs of air pollutants for motor vehicles vary under different operating conditions, which will cause uncertainty in developing emission inventory. Natural gas (NG), considered as a “cleaner” fuel than gasoline, is increasingly being used to reduce combustion emissions. However, information is scarce about how much emission reduction can be achieved by motor vehicles burning NG (NGVs) under real road driving conditions, which is necessary for evaluating the environmental benefits for NGVs. Here, online, in situ measurements of the emissions from nine bi-fuel vehicles were conducted under different operating conditions on the real road. A comparative study was performed for the EFs of black carbon (BC), carbon monoxide (CO), hydrocarbons (HCs) and nitrogen oxides (NOx) for each operating condition when the vehicles using gasoline and compressed NG (CNG) as fuel. BC EFs were reported in part I. The part II in this paper series reports the influence of operating conditions and fuel types on the EFs of CO, HC and NOx. Fuel-based EFs of CO showed good correlations with speed when burning CNG and gasoline. The correlation between fuel-based HC EFs and speed was relatively weak whether burning CNG or gasoline. The fuel-based NOx EFs moderately correlated with speed when burning CNG, but weakly correlated with gasoline. As for HC, the mileage-based EFs of gasoline vehicles are 2.39–12.59 times higher than those of CNG vehicles. The mileage-based NOx EFs of CNG vehicles are slightly higher than those of gasoline vehicles. These results would facilitate a detailed analysis of the environmental benefits for replacing gasoline with CNG in light duty vehicles.

Emission of carbon monoxide, total hydrocarbons and particulate matter during wood combustion in a stove operating under distinct conditions

Wood combustion experiments were carried out to determine the effect of ignition technique, biomass load and cleavage, as well as secondary air supply, on carbon monoxide (CO), total hydrocarbon (THC), particulate matter (PM10) and particle number emissions from a woodstove. Wood from two typical tree species in the Iberian Peninsula was selected: pine (Pinus pinaster) and beech (Fagus sylvatica). The highest CO and total hydrocarbon emission factors (EFs) were observed, respectively, for pine and beech, for high and low fuel loads. The highest PM10 EF was recorded for the operation with low loads for both woods. Secondary air supply produced the lowest PM10 emission factors. The top ignition can decrease the PM10 EF to less than half when compared with the common technique of lighting from the bottom. The lowest particle number emission factors were observed when operating with high loads of split beech logs and when using secondary air supply during the combustion of pine. Regarding particle number distributions, the highest geometric mean diameter (Dg), for both woods, were observed when operating with high loads (with split and non-split wood).

Vehicle Emission and Near-Road Air Quality Modeling for Shanghai, China

In China, motor vehicle emissions have been identified as the major source of urban air pollution. Thus, estimation of emissions and their impact on air quality is necessary. Vehicle emissions vary strongly with region and depend on local vehicle operation and emission performance. This paper uses the MOVES (Motor Vehicle Emission Simulator) model, released by the U.S. Environmental Protection Agency, for the estimation of vehicle emission factors in Shanghai, China. To achieve a convincing emission result, vehicle operation is extracted from massive taxi Global Positioning System (GPS) data, and the emission inventory from MOVES is revised according to China's vehicle emission standards. In addition, deterioration factors are calculated on the basis of vehicle condition. Comprehensive emission factors are generated for Shanghai light-duty vehicles at various average speed levels. The results indicate that emission factors for hydrocarbons, carbon monoxide, and oxides of nitrogen of in-use light vehicles in China are 0.1 to 0.25 g/km, 4 to 7 g/km, and 0.4 to 0.8 g/km, respectively. These amounts are 15, 1.9, and 5.9 times higher than those in the United States, respectively. By 2012, the Environmental Protection Bureau had established 10 monitoring sites in Shanghai and released data for real-time concentrations of particulate matter less than 2.5 μm in diameter, particulate matter less than 10 μm in diameter, nitrogen dioxide (NO2), and sulfur dioxide to the public. On the basis of the new release of data, a field study estimating near-road air quality was conducted with MOVES and the air dispersion model AERMOD. The concentration result shows that the accuracy of near-road NO2 estimation is improved with taxi GPS data and the revised MOVES emission inventory. The study explores the extended application of MOVES by offering a procedure for applying MOVES in non-U.S. regions.

Size-Resolved Polycyclic Aromatic Hydrocarbon Emission Factors from On-Road Gasoline and Diesel Vehicles: Temperature Effect on the Nuclei-Mode

Motor vehicles are a major source of polycyclic aromatic hydrocarbon (PAH) emissions in urban areas. Motor vehicle emission control strategies have included improvements in engine design, exhaust emission control, and fuel reformulation. Therefore, an updated assessment of the effects of the shifts in fuels and vehicle technologies on PAH vehicular emission factors (EFs) is needed. We have evaluated the effects of ambient temperature on the size-resolved EFs of nine US EPA Priority Pollutant PAH, down to 10 nm diameter, from on-road California gasoline light-duty vehicles with spark ignition (SI) and heavy-duty diesels with compression ignition (CI) in summer 2004 and winter 2005. During the winter, for the target PAH with the lowest subcooled equilibrium vapor pressure --benzo[a]pyrene, benzo[ghi]perylene, and indeno[1,2,3-cd]pyrene-- the mass in the nucleation mode, defined here as particles with dp <32 nm, ranged between 14 and 38% for SI vehicles and 29 and 64% for CI vehicles. Our observations of the effect of temperature on the mass of PAH in the nucleation mode are similar to the observed effect of temperature on the number concentration of diesel exhaust particles in the nucleation mode in a previous report.

Emission of trace gases and organic components in smoke particles from a wildfire in a mixed-evergreen forest in Portugal

On May 2009, both the gas and particulate fractions of smoke from a wildfire in Sever do Vouga, central Portugal, were sampled. Total hydrocarbons and carbon oxides (CO2 and CO) were measured using automatic analysers with flame ionisation and non-dispersive infrared detectors, respectively. Fine (PM2.5) and coarse (PM2.5–10) particles from the smoke plume were analysed by a thermal–optical transmission technique to determine the elemental and organic carbon (EC and OC) content. Subsequently, the particle samples were solvent extracted and fractionated by vacuum flash chromatography into different classes of organic compounds. The detailed organic speciation was performed by gas chromatography–mass spectrometry. The CO, CO2 and total hydrocarbon emission factors (gkg−1 dry fuel) were 170±83, 1485±147, and 9.8±0.90, respectively. It was observed that the particulate matter and OC emissions are significantly enhanced under smouldering fire conditions. The aerosol emissions were dominated by fine particles whose mass was mainly composed of organic constituents, such as degradation products from biopolymers (e.g. levoglucosan from cellulose, methoxyphenols from lignin). The compound classes also included homologous series (n-alkanes, n-alkenes, n-alkanoic acids and n-alkanols), monosaccharide derivatives from cellulose, steroid and terpenoid biomarkers, and polycyclic aromatic hydrocarbons (PAHs). The most abundant PAH was retene. Even carbon number homologs of monoglycerides were identified for the first time as biomarkers in biomass burning aerosols.

The emission characteristics of hydrocarbon from Chinese cooking under smoke control

To understand the hydrocarbon emissions in China, the source profile and emission factors of hydrocarbon species from cooking sources were measured. The measured commercial restaurants represented Sichuan cuisine, Zhejiang cuisine, household-style cuisine and Korean-style barbecue, respectively. Forty-one hydrocarbon species were quantified, in which the abundant species were n-butane, iso-butane, 2-methlybutane, pentane, propene, 1-butene, toluene and benzene. The hydrocarbon mixing ratios from Korean barbecue were evidently higher than those from the other Chinese-style restaurants, and the Sichuan-style restaurants had significantly higher emissions of iso-butane and d-limonene. The hydrocarbon source profiles of Chinese cooking were different from the profiles obtained from cooking sources of other cities. While the Korean-style barbecue had abundant species such as light alkanes, propene, benzene and toluene, similar to results for Western barbecue source, the relative percentages of these species were different, probably due to the difference in fuels for cooking. The hydrocarbon emission factors were estimated for Sichuan-style cuisine, which was 0.21g hydrocarbon per kg of meat cooked, much lower than that from the barbecue source.

Characterization of Polycyclic Aromatic Hydrocarbons from the

Diesel fuels governed by U.S. regulations are based on the index of the total aromatic contents. Three diesel fuels, containing various fractions of light cycle oil (LCO) and various sulfur, total polyaromatic, and total aromatic contents, were used in a heavy-duty diesel engine (HDDE) under transient cycle test to assess the feasibility of using current indices in managing the emissions of polycyclic aromatic hydrocarbons (PAHs) from HDDE. The mean sulfur content in LCO is 20.8 times as much as that of premium diesel fuel (PDF). The mean total polyaromatic content in LCO is 28.7 times as much as that of PDF, and the mean total aromatic content in LCO is 2.53 times as much as that of PDF. The total polyaromatic hydrocarbon emission factors in the exhaust from the diesel engine, as determined using PDF L3.5 (3.5% LCO and 96.5% PDF), L7.5 (7.5% LCO and 92.5% PDF), and L15 (15% LCO and 85% PDF) were 14.3, 25.8, 44, and 101 mg L−1, respectively. The total benzo(a)pyrene equivalent (BaPeq) emission factors in the exhaust from PDF, L3.5, L7.5, and L15 were 0.0402, 0.121, 0.219, and 0.548 mg L−1, respectively. Results indicated that using L3.5 instead of PDF will result in an 80.4% and a 201% increase of emission for total PAHs and total BaPeq, respectively. The relationships between the total polyaromatic hydrocarbon emission factor and the two emission control indices, including fuel polyaromatic content and fuel aromatic content, suggest that both indices could be used feasibly to regulate total PAH emissions. These results strongly suggest that LCO used in the traveling diesel vehicles significantly influences PAH emissions.

Correlation between automotive CO, HC, NO, and PM emission factors from on-road remote sensing: implications for inspection and maintenance programs

Carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NO) emission factors (EFs) are measured with a commercial vehicle emissions remote sensing system (VERSS) during a large-scale vehicle exhaust emissions study in Las Vegas. Particulate matter (PM) EFs are simultaneously measured for individual vehicles with a newly developed PM-VERSS based on ultraviolet backscatter light detection and ranging (Lidar). The effectiveness of CO and HC EFs as proxy for NO and PM EFs for spark-ignition vehicles is evaluated. Poor correlations were found between EFs for pollutants on an individual vehicle basis indicating that high EFs for one or more pollutants cannot be used as a predictor of high EFs for other pollutants. Stronger functional relationships became evident after averaging the EF data in bins based on rank-order of a single pollutant EF. Low overlap between the highest 10% emitters for CO, HC, NO, and PM was found. These results imply that for an effective reduction of the four pollutants, inspection and maintenance (I/M) programs, including clean screening, should measure all four pollutants individually. Fleet average CO and HC concentrations determined by gaseous VERSS were compared with fleet average CO and HC concentrations measured at low-idle and at high-idle during local I/M tests for spark-ignition vehicles. The fleet average CO concentrations measured by I/M tests at either idle were about half of those measured by remote sensing. The fleet average high-idle HC concentration measured by I/M tests was about half of that measured by VERSS while low-idle I/M and VERSS HC average concentrations were in better agreement. For a typical vehicle trip, most of the fuel is burned during non-idle conditions. I/M measurements collected during idling conditions may not be a good indicator of a vehicle’s potential to be a high emitter. VERSS measurements, when the vehicle is under a load, should more effectively identify high emitting vehicles that have a large contribution to the mobile emissions inventory.

Determination of non-methane hydrocarbon emission factors from vehicles in a Tunnel in Seoul in May 2000

Measurements of non-methane hydrocarbons (NMHC) were performed at the entrance and exit of the Sangdo tunnel to estimate emission factors (EF) of NMHC from vehicles in May 2000. About 50 species were analyzed by a combined GC/FID and GC/MS system. Ethylene was the most abundant compound, followed by n-butane and acetylene, respectively. Based on the measurement data, the real world vehicular EF in Seoul was estimated. The highest EF value was 89.8 mg (veh-mile)-1 for n-butane, followed by ethylene and toluene.

Quantification of Variability and Uncertainty in Lawn and Garden Equipment NOx and Total Hydrocarbon Emission Factors

Variability refers to real differences in emissions among multiple emission sources at any given time or over time for any individual emission source. Variability in emissions can be attributed to variation in fuel or feedstock composition, ambient temperature, design, maintenance, or operation. Uncertainty refers to lack of knowledge regarding the true value of emissions. Sources of uncertainty include small sample sizes, bias or imprecision in measurements, nonrepresentativeness, or lack of data. Quantitative methods for characterizing both variability and uncertainty are demonstrated and applied to case studies of emission factors for lawn and garden (L&G) equipment engines. Variability was quantified using empirical and parametric distributions. Bootstrap simulation was used to characterize confidence intervals for the fitted distributions. The 95% confidence intervals for the mean grams per brake horsepower/hour (g/hp-hr) emission factors for two-stroke engine total hydrocarbon (THC) and NOx emissions were from -30 to +41% and from -45 to +75%, respectively. The confidence intervals for four-stroke engines were from -33 to +46% for THCs and from -27 to +35% for NOx. These quantitative measures of uncertainty convey information regarding the quality of the emission factors and serve as a basis for calculation of uncertainty in emission inventories (Els).

Emission factors of hydrocarbons, halocarbons, trace gases and particles from biomass burning in Brazil

Airborne measurements of the emissions of gases and particles from 19 individual forest, cerrado, and pasture fires in Brazil were obtained during the Smoke, Clouds, and Radiation‐Brazil (SCAR‐B) study in August‐September 1995. Emission factors were determined for a number of major and minor gaseous and particulate species, including carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen oxides, methane, nonmethane hydrocarbons, halocarbons, particulate (black and organic) carbon, and particulate ionic species. The magnitude of the emission factors for gaseous species were determined primarily by the relative amounts of flaming and smoldering combustion, rather than differences in vegetation type. Hydrocarbons and halocarbons were well correlated with CO, which is indicative of emissions primarily associated with smoldering combustion. Although there was large variability between fires, higher emission factors for SO2and NOχwere associated with an increased ratio of flaming to smoldering combustion; this could be due to variations in the amounts of sulfur and nitrogen in the fuels. Emission factors for particles were not so clearly associated with smoldering combustion as those for hydrocarbons. The emission factors measured in this study are similar to those measured previously in Brazil and Africa. However, particle emission factors from fires in Brazil appear to be roughly 20 to 40% lower than those from North American boreal forest fires.

Real-World Measurements of Exhaust and Evaporative Emissions in the Cassiar Tunnel Predicted by Chemical Mass Balance Modeling

The chemical mass balance model has been used to separate non-methane hydrocarbon emission factors measured in the Cassiar tunnel study into exhaust and evaporative emission factors. The local gasoline composition has been used as a real-world surrogate profile for exhaust emissions and has been demonstrated to result in vastly improved model performance compared to the performance obtained with the use of an exhaust profile derived from dynamometer testing. Because of the approach used, the combustion and unburned gasoline components of exhaust emission gases could be estimated separately. Unburned gasoline was found to comprise 63.4 plus or minus 7.0% of exhaust gases for light-duty vehicles operating in steady-state driving conditions in this study. On-road benzene emissions were found to split 71%/27%/2% between the combustion, unburned gasoline, and evaporative sources. Evaporative non-methane hydrocarbons were found to represent 10.3 plus or minus 0.8% of the total on-road emission rate on average. The apportionment of total NMHC emission factors to exhaust and evaporative emission factors allowed a detailed comparison to exhaust and on-road evaporative emission factors predicted by the MOBILE4.1C and MOBILE5C models. (A)

Evaporation Loss of Hydrocarbon in Handling Petroleum

Evaporation losses of hydrocarbons from various sources, such as refinery plants, oil terminals and gas stations, were studied. A correlation involving the volume of discharged gas, temperature and hydrocarbon concentration was derived for crude oil and petroleum products. These gas emission sources were classified according to their mode of evaporation. As a result, hydrocarbon emission factors in terms of annual mean value were obtained for various emission sources, such as cone and floating roof tanks, loading tankers, tank trucks and gas stations; and also the hydrocarbon emission factors far crude oil and such petroleum products as naphtha, gasoline, kerosene, diesel oil and fuel oil. The hydrocarbon emission factors obtained in this study were smaller than those presented by the U. S. EPA.The calculated hydrocarbon emission factor for loading a tanker which was calculated for the first time, was less than 1/5 of that for loading a tank truck. The hydrocarbon emission factor for loading various kinds of vessels with kerosene and diesel oil was about 1/500 of that for loading the same types of vessels with gasoline.