scholarly journals Detailed Expressions and Methodologies for Measuring Flare Combustion Efficiency, Species Emission Rates, and Associated Uncertainties

2014 ◽  
Vol 53 (49) ◽  
pp. 19359-19369 ◽  
Author(s):  
Darcy J. Corbin ◽  
Matthew R. Johnson
Keyword(s):  
Combustion Efficiency ◽  
Emission Rates ◽  
Flare Combustion

scholarly journals The Effect of Varying Engine Conditions on Unregulated VOC Diesel Exhaust Emissions

2017 ◽  
Author(s):  
Kelly L. Pereira ◽  
Rachel Dunmore ◽  
James Whitehead ◽  
M. Rami Alfarra ◽  
James D. Allan ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Exhaust Emissions ◽  
Combustion Efficiency ◽  
Emission Factors ◽  
Diesel Emissions ◽  
Exhaust Gas ◽  
Emission Rates ◽  
Gas Composition ◽  
Engine Combustion ◽  
Exhaust Gas Emissions

Abstract. An extensive set of measurements were performed to investigate the effect of different engine conditions (i.e. load, speed, temperature, "driving scenarios") and emission control devices (with/without diesel oxidative catalyst, DOC) on the composition and abundance of unregulated exhaust gas emissions from a light-duty diesel engine. Exhaust emissions were introduced into an atmospheric chamber and measured using thermal desorption comprehensive two-dimensional gas chromatography coupled to a flame ionisation detector (TD-GC×GC-FID). In total, 16 individual and 8 groups of volatile organic compounds (VOCs) were measured in the exhaust gas, ranging from volatile to intermediate volatility. The total speciated VOC (∑SpVOC) emission rates varied significantly with different engine conditions, ranging from 70 to 9268 milligrams of VOC mass per kilogram of fuel burnt (mg kg-1). ∑SpVOC emission rates generally decreased with increasing engine load and temperature, and to a lesser degree, engine speed. The exhaust gas composition changed as a result of two main influencing factors, the DOC hydrocarbon (HC) removal efficiency and engine combustion efficiency. Increased DOC HC removal efficiency and engine combustion efficiency resulted in a greater percentage contribution of the C7 to C12 branched aliphatics and C7 to C12 n-alkanes, respectively, to the ∑SpVOC emission rate. The investigated DOC removed 46 ± 10 % of the ∑SpVOC emissions, with removal efficiencies of 83 ± 3 % for the single-ring aromatics and 39 ± 12 % for the aliphatics (branched and straight-chain). The DOC aliphatic removal efficiency generally decreased with increasing carbon chain length. The emission factors of n-nonane to n-tridecane were compared with on-road diesel emissions from a highway tunnel in Oakland California. Comparable emission factors were from experiments with relatively high engine loads and speeds, engine conditions which are consistent with the driving conditions of the on-road diesel vehicles. Emission factors from low engine loads and speeds (e.g. cold-start) showed no agreement with the on-road diesel emissions as expected, with the emission factors observed to be 2 to 8 times greater. To our knowledge, this is the first study which has explicitly discussed the effect of the DOC HC removal efficiency and combustion efficiency on the exhaust gas composition. With further work, compositional differences in exhaust gas emissions as a function of engine temperature, could be implemented into air-quality models, resulting in improved refinement and better understanding of diesel exhaust emissions on local air quality.

Comparison of Remote Sensing and Extractive Sampling Measurements of Flare Combustion Efficiency

2012 ◽  
Vol 51 (39) ◽  
pp. 12621-12629 ◽  
Author(s):  
Joda Wormhoudt ◽  
Scott C. Herndon ◽  
Jon Franklin ◽  
Ezra C. Wood ◽  
Berk Knighton ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Combustion Efficiency ◽  
Flare Combustion

scholarly journals Technical note: Use of an atmospheric simulation chamber to investigate the effect of different engine conditions on unregulated VOC-IVOC diesel exhaust emissions

2018 ◽  
Vol 18 (15) ◽  
pp. 11073-11096 ◽  
Author(s):  
Kelly L. Pereira ◽  
Rachel Dunmore ◽  
James Whitehead ◽  
M. Rami Alfarra ◽  
James D. Allan ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Engine Speed ◽  
Emission Rate ◽  
Combustion Efficiency ◽  
Exhaust Gas ◽  
Emission Rates ◽  
Gas Composition ◽  
Engine Combustion ◽  
Single Ring ◽  
Simulation Chamber

Abstract. Diesel exhaust emissions were introduced into an atmospheric simulation chamber and measured using thermal desorption (TD) comprehensive two-dimensional gas chromatography coupled to a flame ionisation detector (GC × GC-FID). An extensive set of measurements were performed to investigate the effect of different engine conditions (i.e. load, speed, “driving scenarios”) and emission control devices (with or without diesel oxidative catalyst, DOC) on the composition and abundance of unregulated exhaust gas emissions from a light-duty diesel engine, fuelled with ultra-low sulfur diesel (ULSD). A range of exhaust dilution ratios were investigated (range = 1 : 60 to 1 : 1158), simulating the chemical and physical transformations of the exhaust gas from near to downwind of an emission source. In total, 16 individual and 8 groups of compounds (aliphatics and single-ring aromatics) were measured in the exhaust gas ranging from volatile to intermediate volatility (VOC-IVOC), providing both detailed chemical speciation and groupings of compounds based on their structure and functionality. Measured VOC-IVOC emission rates displayed excellent reproducibility from replicate experiments using similar exhaust dilution ratios. However, at the extremes of the investigated exhaust dilution ratios (comparison of 1 : 60 and 1 : 1158), measured VOC-IVOC emission rates displayed some disagreement owing to poor reproducibility and highlighted the importance of replicate sample measurements. The investigated DOC was found to remove 43±10 % (arithmetic mean ± experimental uncertainty) of the total speciated VOC-IVOC (∑SpVOC-IVOC) emissions. The compound class-dependant removal efficiencies for the investigated DOC were 39±12 % and 83±3 % for the aliphatics and single-ring aromatics, respectively. The DOC aliphatic removal efficiency generally decreased with increasing carbon chain length. The ∑SpVOC-IVOC emission rates varied significantly with different engine conditions, ranging from 70 to 9268 mg kg−1 (milligrams of mass emitted per kilogram of fuel burnt). ∑SpVOC-IVOC emission rates generally decreased with increasing engine load and temperature, and to a lesser degree, engine speed. The exhaust gas composition changed considerably as a result of two influencing factors: engine combustion and DOC hydrocarbon (HC) removal efficiency. Increased engine combustion efficiency resulted in a greater percentage contribution of the C7 to C12 n-alkanes to the ∑SpVOC-IVOC emission rate. Conversely, increased DOC HC removal efficiency resulted in a greater percentage contribution of the C7 to C12 branched aliphatics to the ∑SpVOC-IVOC emission rate. At low engine temperatures (<150 ∘C, below the working temperature of the DOC), the contribution of n-alkanes in the exhaust gas increased with increasing combustion efficiency and may be important in urban environments, as n-alkanes are more efficient at producing secondary organic aerosol (SOA) than their branched counterparts. At very high engine temperatures (maximum applied engine speed and load, engine temperature = 700 ∘C), the n-alkane contribution increased by a factor of 1.6 times greater than that observed in the cold-start experiment (most similar to unburnt fuel) and may suggest liquid-fuel-based estimates of SOA yields may be inconsistent with exhaust SOA yields, particularly at high engine speeds and loads (i.e. high engine temperatures). Emission rates were found to be 65 times greater from a cold-start experiment than at maximum applied engine speed and load. To our knowledge, this is the first study which uses an atmospheric simulation chamber to separate the effects of the DOC and combustion efficiency on the exhaust gas composition.

scholarly journals In-Home Emissions Performance of Cookstoves in Asia and Africa

Atmosphere ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 290 ◽  
Author(s):  
Michael A. Johnson ◽  
Charity R. Garland ◽  
Kirstie Jagoe ◽  
Rufus Edwards ◽  
Joseph Ndemere ◽  
...  
Keyword(s):  
Real World ◽  
Laboratory Testing ◽  
Limit Of Detection ◽  
Field Studies ◽  
Combustion Efficiency ◽  
Total Carbon ◽  
World Health ◽  
Emission Rates ◽  
Water Boiling Test ◽  
Health Organization

This paper presents results from eight field studies in Asia and Africa on the emissions performance of 16 stove/fuel combinations measured during normal cooking events in homes. Characterizing real-world emissions performance is important for understanding the climate and health implications of technologies being promoted as alternatives to displace baseline cooking stoves and fuels. Almost all of the stove interventions were measured to have substantial reductions in PM2.5 and CO emissions compared to their respective baseline technologies (reductions of 24–87% and 25–80%, for PM2.5 and CO emission rates, respectively), though comparison with performance guidance from the World Health Organization (WHO) and the International Organization for Standardization (ISO) suggests that further improvement for biomass stoves would help realize more health benefits. The emissions of LPG stoves were generally below the WHO interim PM2.5 emissions target (1.75 mg/min) though it was not clear how close they were to the most aspirational ISO (0.2 mg/min) or WHO (0.23 mg/min) targets as our limit of detection was 1.1 mg/min. Elemental and organic carbon emission factors and elemental-to-total carbon ratios (medians ranging from 0.11 to 0.42) were in line with previously reported field-based estimates for similar stove/fuel combinations. Two of the better performing forced draft stoves used with pellets—the Oorja (median ET/TC = 0.12) and Eco-Chula (median ET/TC = 0.42)—were at opposite ends of the range, indicating that important differences in combustion conditions can arise even between similar stove/fuel combinations. Field-based tests of stove performance also provide important feedback for laboratory test protocols. Comparison of these results to previously published water boiling test data from the laboratory reinforce the trend that stove performance is generally better during controlled laboratory conditions, with modified combustion efficiency (MCE) being consistently lower in the field for respective stove/fuel categories. New testing approaches, which operate stoves through a broader range of conditions, indicate potential for better MCE agreement than previous versions of water boiling tests. This improved agreement suggests that stove performance estimates from a new ISO laboratory testing protocol, including testing stoves across low, medium, and high firepower, may provide more representative estimates of real-world performance than previously used tests. More representative results from standardized laboratory testing should help push stove designs toward better real-world performance as well as provide a better indication of how the tested technologies will perform for the user.

A Validation of Flare Combustion Efficiency Predictions From Large Eddy Simulations

2015 ◽  
Vol 1 (2) ◽  
Author(s):  
Anchal Jatale ◽  
Philip J. Smith ◽  
Jeremy N. Thornock ◽  
Sean T. Smith ◽  
Michal Hradisky
Keyword(s):  
Experimental Data ◽  
Combustion Efficiency ◽  
Large Eddy Simulations ◽  
Posterior Distributions ◽  
Predictive Capability ◽  
Likelihood Functions ◽  
Large Eddy ◽  
Consistency Constraint ◽  
Flare Combustion ◽  
Entrained Air

Societal concerns about the widespread use of flaring of waste gases have motivated methods for predicting combustion efficiency from industrial flare systems under high crosswind conditions. The objective of this paper is to demonstrate, with a quantified degree of accuracy, a prediction procedure for the combustion efficiency of industrial flares in crosswind by using large eddy simulations (LES). LES is shown to resolve the important mixing between fuel and entrained air governing the extent of reaction to within less than a percent of combustion efficiency. The experimental data from the 4-in. flare tests performed at the CanmetENERGY wind tunnel flare facility were used as experimentally measured metrics to validate the simulation with quantified uncertainty. The approach used prior information about the models and experimental data and the associated likelihood functions to determine informative posterior distributions. The model values were subjected to a consistency constraint, which requires that all experiments and simulations be bounded by their individual experimental uncertainty. The final result was a predictive capability (in the nearby regime) for flare combustion efficiency where no/sparse experimental data are available, but the validation process produces error bars for the predicted combustion efficiency.

Impacts of Emission Variability and Flare Combustion Efficiency on Ozone Formation in the Houston–Galveston–Brazoria Area

2012 ◽  
Vol 51 (39) ◽  
pp. 12593-12599 ◽  
Author(s):  
Radovan T. Pavlovic ◽  
Fahad M. Al-Fadhli ◽  
Yosuke Kimura ◽  
David T. Allen ◽  
Elena C. McDonald-Buller
Keyword(s):  
Combustion Efficiency ◽  
Ozone Formation ◽  
Flare Combustion
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