Correlation Between Speciated Hydrocarbon Emissions and Flame Ionization Detector Response for Gasoline/Alcohol Blends

Abstract

The U.S. renewable ftiel standard has made it a requirement to increase the production of ethanol and advanced biofuels to 36 billion by 2022. Ethanol will be capped at 15 billion, which leaves 21 billion to come from other sources such as butanol. Butanol has a higher energy density and lower affinity for water than ethanol. Moreover, alcohol fueled engines in general have been shown to positively affect engine-out emissions of oxides of nitrogen and carbon monoxide compared with their gasoline fueled counterparts. In light of these developments, the variety and blend levels of oxygenated constituents is likely to increase in the foreseeable future. The effect on engine-out emissions for total hydrocarbons is less clear due to the relative insensitivity of the fiame ionization detector (FID) toward alcohols and aldehydes. It is well documented that hydrocarbon (HC) measurement using a conventional FID in the presence of oxygenates in the engine exhaust stream can lead to a misinterpretation of HC emissions trends for alcohol fuel blends. Characterization of the exhaust stream for all expected hydrocarbon constituents is required to accurately determine the actual concentration of unburned fuel components in the exhaust. In addition to a conventional exhaw^t emissions bench, this characterization requires supplementary instrumentation capable of hydrocarbon speciation and response factor independent quantification. Although required for certification testing, this sort of instrumentation is not yet widely available in engine development facilities. Therefore, an attempt is made to empirically determine FID correction factors for oxygenate fuels. Exhaust emissions of an engine fueled with several blends of gasoline and ethanol, n-butanol and iso-Butanol were characterized using both a conventional FID and aFourier transform infrared. Based on these results, a respon.se factor predicting the actual hydrocarbon emissions based solely on FID results as a fwiction of alcohol type and content is presented. Finally, the correlation derived from data pre,sented in this study is compared with equations and results found in the literature.

Emissions of modern light duty ethanol flex-fuel vehicles over different operating and environmental conditions

“…The correction of the HC emission measurement of ethanol content fuels is out of the scope of this study. More details can be found elsewhere [15][16][17].…”

Impact of ethanol containing gasoline blends on emissions from a flex-fuel vehicle tested over the Worldwide Harmonized Light duty Test Cycle (WLTC)

“…Previous studies have pointed out a lack of selectivity of the heated FID towards oxygenated hydrocarbon compounds emitted in the exhaust from engines fuelled with high ethanol blended mixtures [28,29]. Therefore, the time-resolved THC volumetric concentration measured with the FID were corrected using the concentrations measured with the FTIR of ethanol, methanol, formaldehyde and acetaldehyde, and the FID response factor for each of them, as described by Clairotte et al [11].…”

Investigating the Combustion and Emissions Characteristics of Biomass-Derived Platform Fuels as Gasoline Extenders in a Single Cylinder Spark-Ignition Engine

“…Exhaust emissions were sampled 200 mm downstream of the of engine exhaust valve and fed via heated lines to a Horiba MEXA-9100EGR automotive gas analyser rack for measuring gaseous emissions, and to a Cambustion DMS500 differential mobility spectrometer to determine the number and size distribution of particulates in the exhaust. The Horiba analyser rack was fitted with a non-dispersive infrared absorption analyser for CO (±1 ppm) and CO2 (±0.01 %) measurement, a flame ionization detector for THC (±10 ppm) measurement (though it should be noted that no compensation was made the for presence of ethanol in the tested fuels; previous studies have shown that misinterpretation of FID measured THC levels can occur in fuels containing alcohols [28]), a magnetopneumatic analyser for oxygen (±0.1 %) measurement, and a chemiluminescence analyser to measure NOx (±1 ppm) concentrations in the exhaust gas. An IKA C1 bomb calorimeter was used to measure the higher heating values of the test fuels, from which the lower heating value for each was calculated.…”