Data and Methods

• Most common methods for measuring carbonyl emissions: GC-MS, GC-FID, UV-HPLC; aggregate over entire drive cycle FTIR – collect emissions spectra on

second-by-second basis=> high-resolution data

• Dynamometer testing: Light-duty diesel (LDD) Volkswagen

engine 2-hour drive cycle based on driving in

downtown Burlington, VT 1-hour transient phase, followed

by 3 steady-state phases

• Biodiesel: Waste vegetable oil (WVO) Blends of B0 (pure petroleum diesel),

B10, B20, B50, and B100 (pure biodiesel)

• MKS MultiGas 2030 High Speed software-Quantified 28 gases in exhaust emissions:

Research Question

• What emissions trends can be seen in the lab data obtained via FTIR spectral analysis for 5 WVO biodiesel blends for a light-duty diesel (LDD) engine? Do MSATs and criteria pollutants

behave similarly?

Project Funded by Barrett Scholarship Research

Program (5/14/2014-8/22/2014)

Research Advisor: Dr. Britt A. Holmén

(University of Vermont)

Background and Introduction• Biodiesel has become more preferable over

petroleum diesel as a renewable fuel for vehicles7

• While known to reduce CO, PM, HC, and sulfate tailpipe emissions, some studies have shown that biodiesel combustion may increase other harmful emissions, including NOx and mobile source air toxics (MSATs), such as carbonyls3,7,9

MSAT = carcinogenic/highly toxic organic compounds

• Biodiesel = fatty acid methyl esters (FAMEs) Diesel = straight chain alkanes

• Relationship between effect of biodiesel content in fuel on carbonyl emissions largely inconclusive: Increase carbonyl emissions – due to

oxygenated nature of biodiesel fuel2

Reduce carbonyl emissions – higher oxidation state of fuel may result in more complete combustion6

1,2,4-trimethylbenzene 1,3,5-trimethylbenzene 2-heptanone 2-pentanone acetaldehyde acetone acrolein benzaldehyde (butanal) benzene butyraldehyde carbon monoxide (CO) carbon dioxide (CO2) crotonaldehyde

ethyl benzene formaldehyde water heptane hexane m-xylene nitrous oxide (N2O) ammonia (NH3) nitrogen oxide (NO) nitrogen dioxide (NO2) o-xylene propanal (propionaldehyde) styrene toluene

Results and Analysis• CO, CO2, formaldehyde, NO, and NO2 measured consistently above detection limits throughout the entire drive cycle

(Highlighted in red in compound list)

• Plots for formaldehyde and CO2 shown for comparison of the trends displayed by product of incomplete combustion vs. a product of complete combustion, respectively

Average Pollutant Emissions Concentrations vs. Time as a Function of Biodiesel Fuel Content (Bio%)

AbstractThis study focused on using Fourier Transform Infrared (FTIR) spectroscopy to assess the effect of using biodiesel fuel blends on mobile source air toxic (MSAT) exhaust emissions. Infrared spectra collected at the University of Vermont from June-October 2013 of waste vegetable oil (WVO) biodiesel exhaust for B0, B10, B20, B50, and B100 blends were reprocessed using MKS MultiGas software for 28 regulated gases and air toxics. Of the air toxics, formaldehyde was present in the highest concentrations, while all others were measured in very small quantities or fell below the detection limit. It was found that formaldehyde emissions decreased with higher biodiesel fuel content. Increasing the engine load also reduced formaldehyde and CO emissions due to more complete combustion.

Pollutant Concentration vs. Biodiesel Fuel Content (%) and Drive Cycle Phase

Engine start-up spike cut off; extends to ~260 ppm

Increasing Bio% => Lower emissions

Increasing %Load => Lower emissions

Increasing %Load => Higher emissions

Bio% => Little effect

5% load

36% load

50% load

12% load

Conclusions• From literature review, the most prevalent MSATs found in both biodiesel and

diesel were formaldehyde and acetaldehyde However, past studies focused on heavy-duty diesel (HDD) engines

• Formaldehyde was the only MSAT measured consistently above detection limits

• Biodiesel fuel content and engine operating conditions have significant effects on pollutant emissions CO, formaldehyde – reduced with increasing engine load and increasing Bio%

Both are products of incomplete combustion CO2 – not affected by Bio%, direct relationship with engine load NO – increased with Bio% at low engine load; otherwise not affected NO2 – Bio% had no effect until at higher loads; reduced with Bio% at high load

• Future work: investigate low detection of acetaldehyde – inconsistent with existing literature Potential interference in IR spectra between acetaldehyde and formaldehyde Difference between HDD and LDD exhaust emissions

1. Cazier F., Delbende A., Nouali H., Hanoune B., Pillot D., Vidon R., Perret P., Tassel P. 18th International Symposium – Transport and Air Pollution, 2010.

2. Corrêa S., Arbilla G. Atmospheric Environment, 2008, 42, pp 769-775.3. Energy Efficiency and Renewable Energy (EERE) – U.S. Department of Energy. 2013.

<http://www.afdc.energy.gov/vehicles/diesels_emissions.html>.4. Feralio, T., Holmén, B.A. 2014 (in progress).

5. Goshen College. 2014. <http://www.goshen.edu/chemistry/biodiesel/chemistry-of/>.6. Guariero LLN., Periera P., Torres E., da Rocha G., de Andrade J. 2008, 42 (35), pp 8211–8218.7. Knothe, Gerhard. Energy and Fuels, 2008, 22, 1358-1364.8. Turrio-Baldassarri et al, 20039. United States Environmental Protection Agency. 2002.

<http://www.epa.gov/otaq/models/analysis/biodsl/p02001.pdf>.

(Feralio, 2014)

Increasing %Load => Lower emissions

Biodiesel => Lower emissions

Increasing %Load => Higher emissions

Summary of Observed Effects of Bio% and %Load on Emissions

• Most prevalent MSATs in diesel and biodiesel exhaust1,2,6,8

Formaldehyde Acetaldehyde Acrolein Propionaldehyde

Butyraldehyde Benzaldehyde Toluene Crotonaldehyde

Diesel

Biodiesel

References

(Image credits: Goshen College)