Air Pollutants From Biodiesel Fuel Usage

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UNIVERSITY OF CINCINNATI

Date:

I, ,

hereby submit this original work as part of the requirements for the degree of:

in

It is entitled:

Student Signature:

This work and its defense approved by:

Committee Chair:

26-Nov-2007

Aisha Tzillah

Master of Science

Environmental Engineering

The Emissions of Criteria Air Pollutants from Biodiesel Fuel Usage

Mingming Lu, PhD

Edwin Corporan

Sumana Udom Keener, PhD

Min min Lu PhD

Edwin Cor oran

Sumana Udom Keener PhD

Aisha Tzillah


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The Emissions of Selected Air Pollutants from Biodiesel Fuel Usage

A thesis submitted to the

Division of Research and Advanced Studies of the University of Cincinnati

In partial fulfillment of the requirement for the degree of

MASTER OF SCIENCE

In the Department of Civil and Environmental Engineering of the College of Engineering

2008

By:Aisha Tzillah

Bachelors of Science in Chemical Engineering, University of Cincinnati 1998

Committee:Dr. Mingming Lu (Chair)

Dr. Sumana KeenerEdwin Corporan, P.E.


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Abstract

Diesel-powered compression ignited engines contribute large amounts of sub-micronparticulate matter to the environment and have been shown to contribute to atmosphericgreenhouse gases and deleterious health effects. Biodiesel is a proposed alternative bio-fuel produced through transesterification, a process in which organically derived oilscombine with a methyl or ethyl alcohol in the presence of a catalyst, typically potassiumor sodium hydroxide, to form ethyl or methyl ester. This biomass derived ethyl or methylester is non-toxic, less odorous, biodegradable, renewable, and safer to handle thanpetroleum diesel. Biodiesel can mix with conventional petroleum diesel fuel or used as a

neat fuel in compression ignited engines. The main objectives of the research are tocompare selected emissions of petroleum diesel fuel with biodiesel fuel and fuel blends,soybean as the source oil, under different engine conditions in order to determine itsimpact on air quality. A non-road diesel engine generator allowed for thecharacterization of the emissions from operating on petroleum diesel fuel, B50, andB100. The particulate matter and gaseous emissions were collected with a high-volumesingle dilution sampler and the exhaust stream was evaluated with a gas analyzer. Thefilters utilized for particulate matter collection and the adsorbents employed for gaseouspollutant collection were extracted for organic analysis with GC/MS instrument. Theorganic composition of the fuels and the emitted particulate matter and gaseous pollutantswere compared at various engine loads. The use of biodiesel in compression ignitionengines has shown to be a viable alternative to petroleum diesel. Biodiesel is anenvironmentally sustainable fuel that does not contain sulfur or aromatics and maydecrease the overall detrimental effects of diesel-powered engines.


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Table of Contents

Outline..i

List of Tables.......iiList of Figures......iiList of Tables in Appendix A....viiList of Tables in Appendix B...viiiList of Tables in Appendix C...viii

Outline

1. Introduction11.1.Petroleum Diesel Fuel.11.2.Biodiesel Fuel.31.3.Research Objective.8

2. Experimental Design and Method.92.1.Sampling Method..132.2.Extraction Method202.3.Analytical Method21

3. Results and Discussion233.1.Sampling Analysis23

3.1.1. Temperature Stability of the Diesel Engine Generator..233.1.2. Sampling Parameters.253.1.3. PM Mass Collected Under Actual Experimental Conditions....253.1.4. Fuel and Energy Consumption..26

3.2.Particulate Analysis..293.2.1. Diesel Particulate Matter (PM)......29

3.3.Exhaust Gas Analysis...373.3.1. Temperature...383.3.2. Carbon Monoxide..393.3.3. Carbon Dioxide..403.3.4. Oxides of Nitrogen (NOx)..403.3.5. Percent Oxygen..41

3.4.Chemical Composition Analysis..433.4.1. Soluble Fractions of PM........433.4.2. n-Alkanes...443.4.3. Polycyclic Aromatic Hydrocarbons...603.4.4. Methyl Esters.703.4.5. Compound Percentages in Total Identified Organics80

4. Conclusion and Recommendations......825. References86


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List of Tables

Table 2-1: ASTM Fuel properties of Peter Cremer Nexsol Biodiesel.......12

Table 2-2: Soybean Methyl Ester Formula, from National Biodiesel Board....13

Table 3-1: Real over rated power output percentage for B0, B50, and B100....24

Table 3-2: Performance characteristics of dilution sampler......25

Table 3-3: Actual Experimental Conditions for B0, B50, and B100 over the loads.26

Table 3-4: Average Fuel Consumption for B0, B50, and B100 (gal/hr)...27

Table 3-5: Average Energy Consumption (kJ/hr) for B0, B50, and B10028Table 3-6: Average PM Emissions for B0, B50, and B100 over all loadings...35

Table 3-7: Average Gaseous Emissions for B0, B50, and B100 over all loadings...42

Table 3-8: Percent Organics Extracted for GC/MS analysis of B0, B50, and B100 at each

sampling load (kW)44

Table 3-9: Total amount of mass collected (mg) for GC/MS analysis of B0, B50, andB100 at each sampling load (kW)......44

Table 3-10: n-Alkane standard elution order and chemical properties..45

Table 3-11: U.S. EPA 16-priority PAH standard elution order and chemical

property..60

Table 3-12: Methyl Ester Rapeseed Oil standard, elution order and chemical property...70

List of Figures

Figure 2-1: B0, B100, and B50 fuel (left to right in image) with pieces of rubber tubing

and sampling lines, aged 6 months....10

Figure 2-2: Schematic of dilution sampling equipment.16

Figure 2-3: Calibration Line of the Dilution Sampler...............18Figure 3-1: Generator engine exhaust temperature stability over the loadings,

Time (minutes) vs. Temperature (C)....25

Figure 3-2: Fuel Consumption (gal/hr) for B0, B50, B100, and Manual Reference.28


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Figure 3-6: PM Concentration (mg/std m3) in Total Sampling Volume for B0, B50, and

B100 over sampling loads (kW)....31

Figure 3-7: PM Emission Rate (g/hr) for B0, B50, and B100 over sampling loads

(kW)...32

Figure 3-8: PM Emission Rate (g/kW-hr) for B0, B50, and B100 over sampling loads 25,

50, and 75 kW....32

Figure 3-9: PM Emission Rate (mg emitted mass/kg of fuel consumed) for B0, B50, and

B100 over sampling loads (kW)34

Figure 3-10: PM Emission Rate (g emitted mass/kJ of fuel consumed) for B0, B50, and

B100 over sampling loads (kW)....34

Figure 3-11: Temperature Profile of exhaust stream (C) for B0, B50, and B100 over

sampling loads (kW)..38

Figure 3-12: Carbon Monoxide (ppm) in the exhaust stream for B0, B50, and B100 over


Figure 3-13: Carbon Dioxide (%) in exhaust stream for B0, B50, and B100 over sampling

loads (kW)......40

Figure 3-14: Oxides of Nitrogen (ppm) in exhaust stream for B0, B50, and B100 over

sampling loads (kW)..41Figure 3-15: Percent Oxygen in exhaust stream for B0, B50, and B100 over sampling

loads (kW)..42

Figure 3-16: Percent Organics Extracted for B0, B50, and B100 over sampling loads

(kW)...43

Figure 3-17: n-Alkanes Concentration (%) in B0 and B50 Fuel...46Figure 3-18: n-Alkane PM Concentration (g/std m3) for B0 over sampling loads

(kW).......................................................................................................................48

Figure 3-19: n-Alkane PM Emission Rate (mg/hr) for B0 over sampling loads


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Figure 3-22: n-Alkane Concentration in Gaseous Phase (g/std m3) for B0 over sampling

loads (kW)......50

Figure 3-23: n-Alkane Gaseous Emission Rate (mg/hr) for B0 over sampling loads

(kW).......................................................................................................................50

Figure 3-24: n-Alkane Gaseous Emission Rate (mg emitted compound/kg fuel consumed)

for B0 over sampling loads (kW)...................51

Figure 3-25: n-Alkane Gaseous Emission Rate (ng emitted compound/kJ fuel consumed)

for B0 over sampling loads (kW)...............51

Figure 3-26: n-Alkane PM Concentration (g/std m3) for B50 over sampling loads

(kW).......................................................................................................................52

Figure 3-27: n-Alkane PM Emission Rate (mg/hr) for B50 over sampling loads (kW)....52

Figure 3-28: n-Alkane PM Emission Rate (mg emitted compound/kg fuel consumed) for

B50 over sampling loads (kW)..53

Figure 3-29: n-Alkane PM Emission Rate (ng emitted compound/kJ fuel consumed) for


Figure 3-30: n-Alkane Concentration in Gaseous Phase (g/std m3) for B50 over

sampling loads (kW)......54

Figure 3-31: n-Alkane Gaseous Emission Rate (mg/hr) for B50 over sampling loads(kW)...................................................................................................................54


for B50 over sampling loads (kW).55


for B50 over sampling loads (kW).55Figure 3-34: n-Alkane PM Concentration (g/std m3) for B100 over sampling loads

(kW)...................................................................................................................56

Figure 3-35: n-Alkane PM Emission Rate (mg/hr) for B100 over sampling loads


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(kW).......................................................................................................................58


for B100 over sampling loads (kW)...............59


for B100 over sampling loads (kW).......59

Figure 3-42: PAH Concentration (%) in B0 and B50 Fuel....61

Figure 3-43: PAH PM Concentration (g/std m3) for B0 over sampling loads (kW)...62

Figure 3-44: PAH PM Emission Rate (mg/hr) for B0 over sampling loads (kW)62

Figure 3-45: PAH PM Emission Rate (mg emitted compound/kg fuel consumed) for B0

over sampling loads (kW)..63

Figure 3-46: PAH PM Emission Rate (ng emitted compound/kJ fuel consumed) for B0


Figure 3-47: PAH Concentration in Gaseous Phase (g/std m3) for B0 over sampling

loads (kW)......64

Figure 3-48: PAH Gaseous Emission Rate (mg/hr) for B0 over sampling loads (kW).64Figure 3-49: PAH Gaseous Emission Rate (mg emitted compound/kg fuel consumed) for


Figure 3-50: PAH Gaseous Emission Rate (ng emitted compound/kJ fuel consumed) for


Figure 3-51: PAH PM Concentration (g/std m

3

) for B50 over sampling loads(kW)...66

Figure 3-52: PAH PM Emission Rate (mg/hr) for B50 over sampling loads (kW)..66

Figure 3-53: PAH PM Emission Rate (mg emitted compound/kg fuel consumed) for B50


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Figure 3-56: PAH Gaseous Emission Rate (mg/hr) for B50 over sampling loads (kW)...68

Figure 3-57: PAH Gaseous Emission Rate (mg emitted compound/kg fuel consumed) for


Figure 3-58: PAH Gaseous Emission Rate (ng emitted compound/kJ fuel consumed) for


Figure 3-59: Methyl Ester Concentration (%) in B50 and B100 Biodiesel Fuel...71

Figure 3-60: Methyl Ester PM Concentration (g/std m3) for B50 over sampling loads

(kW).......................................................................................................................72

Figure 3-61: Methyl Ester PM Emission Rate (mg/hr) for B50 over sampling loads

(kW)...72

Figure 3-62: Methyl Ester PM Emission Rate (mg emitted compound/kg fuel consumed)


Figure 3-63: Methyl Ester PM Emission Rate (ng emitted compound/kJ fuel consumed)


Figure 3-64: Methyl Ester Concentration in Gaseous Phase (g/std m3) for B50 over


Figure 3-65: Methyl Ester Gaseous Emission Rate (mg/hr) for B50 over sampling loads

(kW)...74Figure 3-66: Methyl Ester Gaseous Emission Rate (mg emitted compound/kg fuel

consumed) for B50 over sampling loads (kW)..75

Figure 3-67: Methyl Ester Gaseous Emission Rate (ng emitted compound/kJ fuel

consumed) for B50 over sampling loads (kW)..75

Figure 3-68: Methyl Ester PM Concentration (g/std m

3

) for B100 over sampling loads(kW)...76

Figure 3-69: Methyl Ester PM Emission Rate (mg/hr) for B100 over sampling loads

(kW)...................................................................................................................76


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Figure 3-72: Methyl Ester Concentration in Gaseous Phase (g/std m3) for B100 over


Figure 3-73: Methyl Ester Gaseous Emission Rate (mg/hr) for B100 over sampling loads

(kW)...78

Figure 3-74: Methyl Ester Gaseous Emission Rate (mg emitted compound/kg fuel

consumed) for B100 over sampling loads (kW)79

Figure 3-75: Methyl Ester Gaseous Emission Rate (ng emitted compound/kJ fuel

consumed) for B100 over sampling loads (kW)79

Figure 3-76: Percentage of identified n-Alkanes PM and Gaseous Phase for B0 and

B50.80

Figure 3-77: Percentage of identified PAHs in PM and Gaseous Phase for B0 and

B50.81

Figure 3-78: Percentage of identified Methyl Esters in PM and Gaseous Phase for B50

and B100........81

List of Tables in Appendix A

Table A-1: n-Alkane PM Concentration (g/std m3) for B0, B50, and B100 over


Table A-2: n-Alkane PM Emission Rate (mg/hr) for B0, B50, and B100 over sampling

loads (kW)..90

Table A-3: n-Alkane PM Emission Rate (mg emitted compound/kg fuel consumed) for

B0, B50, and B100 over sampling loads (kW)..91

Table A-4: n-Alkane PM Emission Rate (ng emitted compound/kJ fuel consumed) for

B0, B50, and B100 over sampling loads (kW)..92

Table A-5: n-Alkane Concentration in Gaseous Phase (g/std m3) for B0, B50, and B100


Table A-6: n-Alkane Gaseous Emission Rate (mg/hr) for B0 B50 and B100 over


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Table A-8: n-Alkane Gaseous Emission Rate (ng emitted compound/kJ fuel consumed)

for B0, B50, and B100 over sampling loads (kW)96

List of Tables in Appendix B

Table B-1: PAH PM Concentration (g/std m3) for B0 and B50 over sampling loads

(kW)...97

Table B-2: PAH PM Emission Rate (mg/hr) for B0 and B50 over sampling loads

(kW)...98

Table B-3: PAH PM Emission Rate (mg emitted compound/kg fuel consumed) for B0

and B50 over sampling loads (kW)...99

Table B-4: PAH PM Emission Rate (ng emitted compound/kJ fuel consumed) for B0

And B50 over sampling loads (kW)100

Table B-5: PAH Concentration in Gaseous Phase (g/std m3) for B0 and B50 over

sampling loads (kW)101

Table B-6: PAH Gaseous Emission Rate (mg/hr) for B0 and B50 over sampling

loads (kW)102

Table B-7: PAH Gaseous Emission Rate (mg emitted compound/kg fuel consumed) for

B0 and B50 over sampling loads (kW)103

Table B-8: PAH Gaseous Emission Rate (ng emitted compound/kJ fuel consumed) for

B0 and B50 over sampling loads (kW)104

List of Tables in Appendix C

Table C-1: Methyl Ester PM Concentration (g/std m3) for B50 and B100 over sampling

loads (kW)105Table C-2: Methyl Ester PM Emission Rate (mg/hr) for B50 and B100 over sampling

loads (kW)105

Table C-3: Methyl Ester PM Emission Rate (mg emitted compound/kg fuel consumed)


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Table C-6: Methyl Ester Gaseous Emission Rate (mg/hr) for B50 and B100 over

sampling loads (kW)107

Table C-7: Methyl Ester Gaseous Emission Rate (mg emitted compound/kg fuel

consumed) for B50 and B100 over sampling loads (kW)108

Table C-8: Methyl Ester Gaseous Emission Rate (ng emitted compound/kJ fuel

consumed) for B50 and B100 over sampling loads (kW)108


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1. Introduction

There are two major types of engines utilized currently compression ignited engines

operating on diesel fuel and spark ignited engines operating on gasoline fuel.

Compression ignition engines are widely used in on-road and non-road applications with

high power output and great fuel economy. Although compression ignited engines emit

lesser amounts of carbon monoxide and total hydrocarbon compounds than spark ignited

engines, they form large quantities of fine particulate matter.1 From the United States

Environmental Protection Agency (U.S. EPA) National-Scale Air Toxics Assessment,

diesel emissions are among the substances that pose the greatest relative risk.2 According

to the 1996 U.S. EPA National Air Toxics Inventory, approximately 5.24 x 105 tons per

year of diesel particulate matter was emitted nationwide.

1.1. Petroleum Diesel Fuel

Petroleum diesel fuel consists mainly of saturated and aromatic hydrocarbons. Paraffins,

cycloparaffins, monoaromatics, diaromatics, polynuclear aromatics, and sulfur

compounds are the major compound types typically found in petroleum diesel fuel.3

According to the World Health Organization (WHO), C10 to C28 n-alkanes are the

dominant saturated hydrocarbons for general diesel fuel. Branched alkanes also comprise

a large percentage of the fuel. Aromatic compounds constitute 10 to 30% and the total

concentration of the polycyclic aromatic hydrocarbons (PAHs), such as naphthalene,


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(ultra-low sulfur diesel) on June 1, 2006. For non-road applications, current U.S. EPA

regulation on sulfur content is 500 ppm, which was reduced from 3400 ppm in 2007 and

will be reduced even further to 15 ppm in 2010.

The National Institute of Occupational Safety and Health (NIOSH) and U.S. EPA classify

diesel particulate matter (PM) as a probable human carcinogen.2

Diesel exhaust particles

are essentially sub-micrometer. Due to their median aerodynamic diameter of 0.1 to 0.3

m, with 90% less than 1.0 m, the particles are readily inhaled, and about 10% are

deposited in the alveolar region of the lung. The carcinogenic effect of diesel exhaust

exposure is mainly ascribed to the inhalation of soot particles. According to the U.S.

EPA, emissions from non-road diesel machines are significantly higher than on-road

diesel engines because of lower fuel quality, inadequate engine maintenance, older

engine ages, and less public supervision.4

Diesel emissions contain hundreds of chemical compounds, partitioned in the gaseous

and in the particulate phase.1 Both phases in diesel exhaust contain known or suspected

mutagens and carcinogens, such as PAHs.2 Diesel PM is a complex mixture of organic

and inorganic compounds that exist in particle phase. Organic compounds, which

constitute 20 to 60% of diesel PM, appear as the soluble organic fraction. The organic

carbon fraction is a complex mixture of unburned fuel and hundreds of organic


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carbon and organic carbon.1 Elemental carbon, the diesel soot particles core, is a product

of incomplete combustion. It consists of carbon layers that are structurally similar to

graphite.

1.2. Biodiesel Fuel

Biodiesel is a compression ignition diesel equivalent fuel made from transesterified fatty

acids. Biodiesel is a biodegradable, renewable, nonflammable fuel that may replace

conventional petroleum diesel fuel. The fuel may be used neat (100%) or in blends with

petroleum diesel, as biodiesel is completely miscible in petroleum diesel.5 Biodiesel was

standardized by the American Society for Testing and Materials (ASTM) in 1999 as

provisional standard PS 121-99 and became a full standard, ASTM D6751 in 2002. In

1994 Europe created the biodiesel standard DIN V 51506. Commercial use of biodiesel

as an alternative fuel has occurred since the late 1980s in most countries.4

Biodiesel has been researched as a fuel extender or supplement in various transportation

fuels. According to the United States Department of Energy, Energy Information

Administration, approximately 4,243 thousand barrels of distillate fuel were consumed

per day in 2007. The use of diesel fuel blends containing even relatively small amounts

(5%) of biodiesel could equate to substantial petroleum fuel savings daily.6 Number 2

petroleum diesel fuels are the transportation fuels to which biodiesel is typically


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The chemical process to make biodiesel is known as transesterification and consists of

treating animal fats and vegetable oils, such as soybean, sunflower, and rapeseed, with

reactants methanol or ethanol in the presence of the catalyst, typically sodium or

potassium hydroxide, to obtain a methyl or ethyl ester and glycerin.8 There are more than

350 oil-bearing crops identified; among which sunflower, safflower, soybean, cottonseed,

rapeseed, and peanut oils are considered as potential alternative fuels for diesel engines.9

Fats and vegetable oils are primarily composed of glycerol esters of fatty acids

(triglycerides). In the process of transesterification, the glycerol components of the

triglyceride molecules exchange for a lighter methanol (or ethanol). The product is

composed of fatty acid methyl or ethyl esters, consisting of straight saturated and

unsaturated alkyl groups with C15 to C17 hydrocarbon chains and C14 to C22 alcohol esters

that exhibit varying degrees of un-saturation, depending on source.10 The most widely

used product, soyate methyl ester, is made through a reaction of soybean oil and

methanol.11 Methanol is most commonly used for making biodiesel because of its low

cost.12

Biodiesel is considered nontoxic, and has a higher biodegradability and is less polluting

to water and soil than fossil diesel. According to the United States Department of

Energy, Office of Energy Efficiency and renewable Energy, biodiesel is as biodegradable

as sugar, ten times less toxic than table salt, and degrades about four times faster than


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deposition and poison catalytic converters in vehicles, the use of an oxidation catalyst

engine has a high potential of reducing exhaust-gas components while burning biodiesel

fuel.13

Biodiesel fuels have similar composition whether produced from animal fats or vegetable

oils. The primary difference between the source oils is that the animal fat-based biodiesel

contains more saturated fatty esters. Soybean oil is typically about 12 to 15 % saturated,

while tallow is typically about 50% saturated. This greater saturation raises the cloud

point, or the temperature at which waxy crystals in an oil or fuel form a cloudy

appearance, of animal-fat based biodiesel and has shown to have questionable effects on

the overall combustion and exhaust emissions characteristics of the biodiesel fuel.5

Biodiesel fuels have a kinematic viscosity range 1.9 to 6.0 centistokes (mm2/s) versus 1.3

to 5.8 centistokes for petroleum diesel. The higher viscosity of biodiesel compared to

petroleum diesel makes it an excellent lubricity additive and provides lubricating

properties that may reduce engine wear and extend engine life.14 Replacing diesel fuel

with biodiesel reduces the wear of aluminum, iron, chromium, and lead components in a

diesel engine.15 However, the injection droplet size from the higher viscosity can impact

emissions due to poor distribution of the fuel and increased burning times. The viscosity

of a fuel is important because it affects the atomization of the fuel being injected into the


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around valves, injector tips, and on piston sidewalls and rings.14 Biodiesel is less

compressible than diesel fuel. The pressure in the fuel injection system can develop

faster and with the increased viscosity of biodiesel, this leads to reduced fuel losses

during the injection processes.16

All Number 2 petroleum diesel fuels have relatively high flash points, which measures

the tendency of a fuel to form a flammability mixture with air, typically at 71C (160F);

the flash point of neat biodiesel is even higher, greater than 90C (194F), typically

around 150C (302F). A material with a 90C or greater flash point is considered by

ASTM standards as non-hazardous from storage and fire-hazard point of view.5 The

relatively high flash point of biodiesel makes it less volatile and safer to transport or

handle than petroleum diesel.

Biodiesel fuels may contain residual alcohol from the transesterification process, which

can remove deposits from fuel tanks and lines causing filter plugging during initial use.

Biodiesel has poor oxidation stability, which can result in long-term storage problems.

Biodiesel fuel is an excellent medium for microbial growth.5 Microbes cause fuel system

corrosion and premature filter plugging. Any amount of water contaminating the fuel

will accelerate the microbial growth.16


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energy density of the fuel based upon the lower or net heating value. 5 Diesel fuel is

pumped to the engine on a volumetric basis, and the density of the biodiesel blend ishigher than that of diesel so that a larger mass flow rate for the same fuel volume is

pumped to the engine, resulting in increase in torque and power. However, as the

biodiesel percentage in the fuel increases, the power will decrease below that of diesel

fuel due to the lower heating value and higher viscosity of the biodiesel, possibly

resulting in poorer atomization and incomplete combustion.17

Biodiesel fuel is free from aromatic compounds and contains fuel bound oxygen. It has

an oxygen content of 10 to 11% and this has an effect on particulate matter (PM) and

NOx emissions.18 The oxygen in biodiesel can be used in combustion, especially in the

fuel rich flame zone, for a more complete combustion which can result in increasing the

torque and power and reducing exhaust emissions such as hydrocarbons (HC), smoke,

and carbon monoxide (CO).17 Oxygenated fuel combustion products that minimize soot

formation are those where the oxygen atom from the fuel is bonded to a different carbon

atom in the products. This prevents the carbon atom in the product from forming

unsaturated species that lead to soot or elemental carbon.16 Higher temperatures of

combustion resulting from biodiesel fuel usage results in higher NOx emissions.17

Some fuel system modifications are recommended when operating both on-road and non-


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cause swelling and hardening or cracking of some elastomer seals within the fuel system

and engine. Pure biodiesel fuel is not stable, and its acid content increases over time,which can damage powder metal components. Other areas of concern when operating

with biodiesel fuels include fuel gelation and filter plugging at low temperatures.

Because of biodiesel fuels poor storage and thermal stability, filter plugging, injector

deposits, and blockage of the fuel nozzles and passages can occur.8

1.3. Research Objective

The U.S. EPA conducted a compilation study where publicly available data were utilized

to determine the emission characteristics of biodiesel usage. The majority of the

available data were collected on heavy-duty on-road engines, which demonstrated that

biodiesel use results in a decrease in particulate matter, carbon monoxide, and

hydrocarbon emission with an increase in NOx. It also concluded that non-road engines

and on-road diesel engines respond differently, since non-road engines mainly operate in

transient modes and additional data are required on non-road engines response to

biodiesel.19

As detailed emissions data from biodiesel combustion in non-road engines are limited,

the overall goal of this research is to characterize the emissions of selected air pollutants

from biodiesel fuel blends compared with petroleum diesel fuel while operating a non-


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major methyl ester concentrations in the petroleum and biodiesel blend fuel and exhaust.

Fuel consumption, soluble fraction of the particulate matter, the exhaust stream oxygen,carbon dioxide, and temperature are also measured and compared between biodiesel fuel

blends and petroleum diesel fuel.

2. Experimental Design and Method

For this study, a non-road diesel engine generator was utilized to evaluate compression

ignition emissions while operating on petroleum diesel and biodiesel fuels. The

generator is located at University of Cincinnati Center Hill Research Facilities in

Cincinnati, Ohio. It is a 1992 compression-ignition Generac Power Systems, Inc. liquid

cooled diesel engine generator Model SD080, 5.0 Direct-injection, turbo-charging, 4

cylinders, rated output at 80 kW, 60 Hz, with a 0.8 power factor, 122 hp at rated output,

with a normal engine speed of 1800 rpm, and compression ratio 17.5:1. According to the

diesel engine generator reference manual, the exhaust flow at rated output 60 Hz is 24

m3/min (848 ft3/min) with exhaust temperature at rated output 509C (950F). The

generator is specified to operate on Number 2 diesel fuel with a minimum Cetane number

of 40. The generator had approximately 750 hours of operation prior to usage.

According to the Code of Federal regulations (CFR) Title 40 Part 89.104, Control of

Emissions from New and In-use Non-road Compression Ignition Engines, the useful life

of a non-road engine rated over 37 kW is 8,000 hours or 10 years, whichever comes first.


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the fuels utilized for this study with pieces of rubber tubing and sampling lines aged for

six months. The 100% biodiesel (B100) deteriorated all the rubber tubing as evidenced

by the dark color in the sampling jar. The 50/50 mixture of petroleum and biodiesel

(B50) deteriorated the rubber lining to a much lesser extent.

Figure 2-1: B0, B100, and B50 fuel (left to right in image) with pieces of rubbertubing and sampling lines, aged 6 months

The diesel engine generator was equipped with a 254 mm (10 in.) inner diameter metal

exhaust pipe fashioned after the diesel muffler. This pipe extends across the top of the

generator 1.8 m horizontally, 1.9 m vertically down the side and 2.3 m across, for a well-

mixed exhaust gas with relatively high residence time. The schematic of the dilution

sampling system is depicted in Figure 2-2. The same sampling points were employed

i t tl f h th d f li


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240/480 V, 60 Hz simulated various load conditions from 0 (idle) to 75 kW (maximum

load on the diesel engine generator is 80 kW) by applying steady-state banks of heaters to

the generator with 25 kW increments. To determine the energy output, the voltage and

amperage were recorded. The generator voltage was set at 480 volts and kept constant

with the rated output for all trials at nearly 100%. For all trials, the fuel by-pass

apparatus was employed for fuel addition and fuel consumption data.

The petroleum diesel was On Road Diesel Supreme Ultra-Low Sulfur (ULS) fuel from

Steve Krebs Oil Company supplied by BP Oil Company, labeled with a sulfur content of


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molecular weight of soybean oil methyl ester is 292.2 g/gmol with an average density of

0.88 g/cm3.

Table 2-1 lists the ASTM D 6752 fuel standard specifications and results from Peter

Cremer North America analysis. Table 2-2 lists the biodiesel fuel composition in terms

of the methyl ester content determined from the National Biodiesel Board for a typical

soybean oil methyl ester, calculated using the average fatty acid distribution for soybean

methyl esters.

Table 2-1: ASTM Fuel properties of Peter Cremer Nexsol Biodiesel

Property ASTM Method Limits ResultsFlash Point D93 130C min


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Table 2-2: Soybean Methyl Ester Formula, from National Biodiesel Board

Methyl Ester Formula Molecular

Weight

(g/gmol)

Weight

Percent

Boiling

Point

(C)

Melting

Point

(C)

Density

(g/cm3)

Methyl Palmitate C17H34O2 270.45 12.0 185 34 0.852Methyl Stearate C19H38O2 298.52 5.0 181 37 41 N/A*Methyl Oleate C19H36O2 296.5 25.0 218 N/A 0.874

Methyl Linoleate C19H34O2 294.48 52.0 192 -35 0.889Methyl

LinolenateC19H32O2 292.46 6.0 182 N/A 0.895

*N/A = Data not available

2.1. Sampling Method

A common method for measuring the mass of organic aerosol involves filter collection

and subsequent thermal analysis. Dilution sampling techniques are generally

recommended for studying diesel exhaust emissions. Dilution sampling rapidly cools the

exhaust and mixes it with filtered ambient air. This method simulates the particulate

matter behavior in the environment since the diesel exhaust leaving the pipe is

immediately cooled and diluted with atmospheric air.2

Engine testing procedures for non-road diesel engine is outlined in Federal Test

Procedure 40 CFR Part 89, Control of Emissions from New and In-Use Non-Road

Compression Ignition Engines. In 40 CFR 89.419, Dilute gaseous exhaust sampling

and analytical system description, the dilution sampling system utilizes the CVS concept

as described in 40 CFR Part 1065 Test Procedure and Equipment The constant


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system, as exhaust flow increases, such as during increased load, the dilution air is

decreased and the sampling source is representative of exhaust variations. Because some

compounds present in the exhaust are soluble in water, the flow capacity of the CVS must

be large enough to keep water from condensing in the system.

According to 40 CFR 1065.140, Dilution for gaseous and PM constituents, the

sampling system should maintain sample temperature less than 455C, primary dilution

air at 25C 5C, utilize a HEPA filter to remove any background PM in the dilution air,

a Reynolds number greater than 4,000 in the dilution tunnel, and sufficient length to

cause complete mixing of the exhaust and dilution air, generally recommending at least

10 pipe diameters in length.

Figure 2-2 schematic of the sampling system illustrates the simplified arrangement

employed in the tests for particulate and gaseous sampling. The single dilution system

follows the temperature requirements for CFR Federal Test Procedure for non-road

dilution sampling and basic design parameters, such as inert sampling materials which

are stable at high temperatures, the filter situated 10 tunnel diameters downstream from

where the exhaust enters dilution tunnel, with lengths no more than 50 outside diameters,

gradual bends in the system, with enough residence time for condensation to occur and

turbulent mixing in the dilution tunnel. Constant total flow volume sampling was not


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low dilution ratio minimized this discrepancy. Sampling time for all loads was 30

minutes. At least three runs at each load per fuel combination were analyzed.

The dilution system was equipped with a high volume blower, General Metal Works

Model 2000, Serial Number 10696, 115 volt, 60 cycles, one phase, with a total flow rate

of approximately 300 L/min, used to draw air through the system. The total diluted

sample flow rate was determined with a Magnehelic Gauge, range of 0 to 100 inches of

H2O. The exhaust was diluted with ambient air filtered using a high efficiency

particulate filter (HEPA) with 99.97% removal efficiency and was measured by a Dwyer

Ratemaster Flow Meter, range of 0 to 20 standard cubic feet per minute (scfm) of air.

The PM was collected on quartz fiber filters (Millipore) at temperatures


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Figure 2-2: Schematic of dilution sampling equipment

The primary metal inlet probe was insulated with Virginia Foam insulation tape,

catalogue number K-501, in order to maintain the temperature of the exhaust gas before

mixing with the dilution air. The metal inlet probe had a 10 mm inner diameter, 12.7 mm

outer diameter, 1.2 m in length attached with a Teflon connection 0.4 m in length to the

MagnehelicGauge (Qt)

Non-Road Diesel

Engine

Generator Exhaust Stream

Ambient AirHEPAFilter

PUF/XAD/PUF

Quartz Fiber Filter,90 mm

Dwyer Flow Meter(Qd)

Sampling Port

Blower

Inlet Metal Probe,

1.2 m,10 mm I.D.

Dilution Tunnel,38.1 mm I.D.,

2.2 m

10 in. I.D.

18 m

1.9 m

2.3 m

TeflonConnection,

0.4 m

19.1 mm I.D.,1.3 m

19.1 mm I.D.,1.3 m


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dilution sampler probe was inserted 1.9 m on the traverse of the exhaust stream pipe. The

tubing was rinsed with acetone between runs.

The pressure drop as measured by the Magnehelic gauge (in. of H2O) was calibrated to

the volumetric flow rate with use of a standard Pitot tube. The Pitot tube was used to

measure total dilution stream flow rate at a range of pressure drops before sampling the

engine generator exhaust. To correlate the pressure drop to the flow, the velocity of the

stream was first determined. For a standard pitot tube from Apex Instruments, the air

velocity, Vs, is determined by the following relation:

2/1

49.85

=

ss

s

sPM

pTV , where,

85.49 is the units factor to yield a Vs in units of ft/s, Ms is the stack gas molecular weight,

taken as 29 lb./lb.-mol, Ps is the absolute exhaust stream pressure taken as ambient

barometric pressure (in. of Hg), Ts is the exhaust stream temperature in Rankine, and p

is the velocity head of the exhaust stream gas (pressure drop) measured from a

manometer attached to the Pitot tube in inches of H2O.

Figure 2-3 shows the calibration results and verifies the strong linear correlation of the

pressure drop relating to the volumetric flow rate of the dilution stream. The square root

of the pressure drop measured with the Magnehelic gauge (in. of H 2O) was plotted

against the volumetric flow rate, Qs, calculated from the Pitot tube results (standard liter


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Figure 2-3: Calibration Line of the Dilution Sampler

y = 56.695x

R2

= 0.9981

200

250

300

350

400

450

500

3.5 4.5 5.5 6.5 7.5 8.5

Magnehelic Gauge (P, in. of water)1/2

Qs

(slpm)

The dilution ratio was determined by the following equation (ratio of the dilution air flow

to the exhaust gas flow):dt

d

QQ

Qq

= where, Qd is the dilution flow rate and Qt is the

total flow rate (exhaust gas flow plus dilution gas flow). There is no set guideline for the

dilution ratio in the Federal Test Procedure 40 CFR Part 1065.

In 40 CFR 89.331, Test Conditions, all volumes and volumetric flow rates are

corrected to the temperature and pressure of 0C (273.15 K) and 101.3 kPa (1 atm). The

total sampling volume was corrected to standard conditions by filter temperature, Tm, and

ambient pressure, Pm, with the following relation:mstd

stdm

mstdTP

TPVV = .


32/121

temperature was measured with use of the Fisher Scientific Traceable Hygrometer. The

particulate mass concentration was determined from the total flow over the test period.

The quartz fiber filters were baked at 550C (1,022F) prior to sampling for a minimum

of 12 hours, to reduce residual carbon levels associated with new filters, and weighed

with Sartorius CP225D Electronic Semi-micro and Analytical Precision Balance 0.1mg, with 0.02 mg standard deviation. After sampling, the filters were stored in a

desiccator for 24 hours at 20C5.6C and ambient pressure, weighed, and then extracted.

After extraction described in section 2.2, the filters were dried and weighed again.

Quartz fiber filters were selected because they are suitable for thermal analysis and

extraction. However, these filters have large surface areas upon which adsorption of

gases can be considerable. Adsorption of organic vapors onto filter during or after

sample collection can overestimate the organic aerosol concentration.3 Significant

pressure drops over the filter can generate underestimation.3

The filters were contained in

covered glass Petri dishes for transportation and storage.

The Testo Gas Analyzer measured the emissions of carbon monoxide (CO), carbon

dioxide (CO2), oxides of nitrogen (NOx), percent oxygen (O2), and exhaust temperature.

Multiple measurements were taken at each load. The Testo Gas Analyzer is not as

accurate as an U.S. EPA standard method; however, it is utilized for a general assessment


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temperature measuring range is -40 to 1,200C (-40 to 2,192F). The CO2 sensor has a

resolution of 0.01% volume with a 20-second reaction time. The O2 sensor has a

measuring range of 0 to 25 % volume with an accuracy of 0.8% volume, a resolution of

0.1% volume, and a 20-second reaction time. The NOx sensor has a range of 0 to 3,000

ppm with an accuracy of 5 ppm and a 30-second reaction time. The Testo Gas Analyzer

was inserted 1.5 m on the horizontal pipe. In 40 CFR 89.309, the analyzers required forgaseous emissions include non-dispersive infrared absorption type, on a dry basis for

carbon monoxide and carbon dioxide analysis and a chemiluminescent detector for

measuring oxides of nitrogen.

2.2. Extraction Method

To analyze the particulate matter for organic composition, the quartz filters underwent

Ultrasonic assisted extraction with the solvent HPLC grade dichloromethane (DCM,

Fisher Scientific). The filters were analyzed individually for the extractions and analysis

for organic composition was performed with a GC/MS (gas chromatography/mass

spectrometry) instrument.

After gravimetric analysis, the filter was rinsed with 100 mL DCM in a volumetric flask,

sealed with aluminum foil and Parafilm and placed in a Branson 1510 sonicator water

bath for 1 hour. Slow vacuum filtration through a 25 mm Alltech Polytetrafluoroethylene


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After filtration, the 100 mL solution was evaporated to approximately 10 mL under a

gentle stream of nitrogen or evaporated in ambient air. The extraction concentration

amount was chosen based on previous studies3 and appropriate component amounts for

GC/MS analysis. The solution was transferred to a vial, stored in the freezer, and

analyzed directly with the GC/MS.

All filters were weighed before and after extractions. The dissolved fraction or percent

soluble is defined as 100*12

32

MM

MM

, where M1 is the mass of the filter after baking and

before sampling, M2 is the mass after sampling and desiccation, and M3 is the mass dried

extracted filter.

To analyze the gas phase for organic composition, the XAD and PUF were weighed,

washed repeatedly with DCM, the solution vacuum filtered to 0.2 m, concentrated under

a nitrogen stream, and analyzed with the GC/MS.

2.3. Analytical Method

Most of the organic compounds typically present in PM extract, such as alkanes, PAHs,

alkylated PAHs, oxygenated PAHs, alkyl benzenes, fatty acids, and esters, can be

analyzed with a GC/MS instrument. A Varian GC/MS system (CP-3800 GC, Saturn


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The chromatographic procedure followed column temperature set at 30C for 2 minutes,

raised to 200C at 10C/min, raised 5C/min to 270C, then at 10C/min to 300C, held

at 300C for 10 minutes for a total analysis time of 45 minutes. The injector was in

splitless mode at a temperature of 280C. Helium was used as the carrier gas with a flow

rate of 1.2 mL/min, and the MS was set as ion trap with a 2.8-minute solvent delay.

Compound identification in total ion chromatogram (TIC) was performed with the

assistance of the National Institute of Standards and Technology (NIST) standard library.

Standards reference compounds acquired from Restek Corporation were utilized for peak

and retention time comparison and mass fragmentation patterns. Eight Peak Index mass

to charge ratio was utilized to confirm the NIST results.

From the chromatogram of intensity (abundance) versus retention time from the GC/MS

analysis, the peaks were compared against three external standards for n-alkanes, PAHs,

and methyl ester content. To obtain the concentration of the particular compound in the

sample, the response factor was first determined as the area of the peak divided by the

concentration within the standard. Compositional analysis with the GC/MS requires

accurate response factors for compound quantification based on external standards.

Response factors were validated by injection of the standard compounds with multilevel

concentrations using the same analytical method. Calibration curves were obtained with

the R2 value greater than 0.96. The peak area divided by the response factor at each


36/121

multiplied to the final extraction volume (mL) over the total sampling volume (m3)

corrected to the standard temperature and pressure.

Before sample analysis, pure DCM was injected into the column to ensure stable status of

the instrument and identify possible laboratory contaminants in the samples. All sample

and standard solutions were sealed in vials and stored in the freezer; sample containers,

sampling equipment, and laboratory glassware was cleaned and stored to minimize

contamination from external sources.

3. Results and Discussion

The fuels tested included 100% ultra-low sulfur (ULS) petroleum diesel, 50/50 mixture

of biodiesel and ULS diesel, and 100% biodiesel fuel. The petroleum diesel was On

Road Diesel Supreme ULS petroleum fuel, referred to as B0 (0% biodiesel). The

biodiesel utilized was Peter Cremer North America Soy Methyl Ester Biodiesel. A 50/50

mixture of biodiesel and petroleum diesel fuel is referred to as B50 and 100% biodiesel is

referred to as B100.

3.1. Sampling Analysis

3.1.1. Temperature Stability of the Diesel Engine Generator

Power output for the engine generator was determined from the voltage of the generator


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Table 3-1: Real over rated power output percentage for B0, B50, and B100

Load Real/Rated Power Output (%)

(kW) B0 B50 B100

25 99.70.05 96.21.04 95.550 960.52 99.53.98 93.475 92.31.01 92.41.01 84.2

The diesel engine generator operated at least 15 minutes at each load for temperature

stabilization and steady state conditions before the start of the dilution sampling.

According to 40 CFR 1065.530, Emission Test Sequence, for testing that involves hot

stabilizing environment measurements, the test should start within 10 minutes of

achieving temperature stability. The exhaust temperature was monitored from the initial

start at each load. Figure 3-1 illustrates temperature variation for B0 (100% ULS

petroleum diesel fuel) as increasing loads are applied to the engine generator from time

zero and that at 15 minutes when steady state was achieved. For most trials, more than

15 minutes for stability were allotted before the initiation of the dilution monitoring. The

results at 15 minutes represent the initial sampling temperatures and are the approximate

values found at each respective load for the petroleum diesel fuel.


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Figure 3-1: Generator engine exhaust temperature stability over the loadings,

Time (minutes) vs. Temperature (C)

75

125

175

225

275

325

0 5 10 15 20

Time (min)

Temperature(C)

0 kW

25 kW

50 kW

75 kW

3.1.2. Sampling Parameters

Table 3-2 refers to the sampling system parameters employed during the experiments.

The dilution ratio is low (~2), sufficient to maintain the filter temperature at an average of

20C (68F). During this high-volume dilution sampling, the filter temperature increased

with the load increasing under similar dilution ratio.

Table 3-2: Performance characteristics of dilution sampler

Parameter Range

Exhaust flow 80 100 L/minDilution air flow, Qd 120 200 L/minTotal flow, Qt 200 300 L/minDilution Ratio ~2

Reynolds Number, flow through mixing duct >10,000, turbulent


39/121

for each fuel at the varying loads. Although constant total flow volume sampling,

collecting the same total volume for each trial as outline in 40 CR 89 and 40 CFR 1065,

was not performed, the low dilution ratio allowed total sampling volume and dilution

volumes for all fuel types at all loads to be within 8% of all trials. All volumes decreased

with load. As volumes decreased during the trial, an integrated average of the volume

was used in determining the volume amounts. Constant total volume generally occurred

at all loads except at the 75 kW loading. At 75 kW, a filter change was required with the

B0 and B50 due to an increased pressure drop across the filter.

Table 3-3: Actual Experimental Conditions for B0, B50, and B100 over the loadsLoad

Setting

(kW)

Mass of

PM

collected,

mg

Total

Volume

std m3

Dilution

Volume

std m3

Ambient

Temp.

C

%

Relative

Humidity

Filter

Temp.

C

0 0 43.43.1 7.250.55 4.430.64 23.63.9 30.45.4 15.625 46.35.7 7.330.23 4.740.22 22.73.2 31.61.4 18.350 38.77.9 7.010.24 4.530.17 25.81.8 28.85.5 21.1

75 55.94.8 5.900.38 3.890.37 28.65.0 30.72.5 23.9B50 0 58.89.6 7.540.18 4.710.20 30.22.4 31.71.6 10.0

25 115.721.2 7.290.11 4.690.15 27.45.0 32.23.5 12.850 65.18.4 7.270.20 4.780.15 25.71.4 31.96.6 15.675 59.77.6 6.751.08 4.400.81 26.52.2 28.03.0 18.3

B100 0 72.611.1 6.970.06 3.970.32 33.31.1 23.82.3 21.125 186.61.7 6.530.19 3.960.05 36.50.7 16.42.4 23.950 105.61.4 6.300.21 4.070.02 35.30.3 14.21.2 26.775 74.40.5 6.190.35 4.110.26 35.60.0 12.00.0 29.4

3.1.4. Fuel and Energy Consumption


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lower or net heating value.5 This is consistent with petroleum diesel having a higher heat

of combustion. The average energy content for biodiesel as analyzed for OKI Analytical

Laboratory is 124,513 BTU/gal. The average energy content for petroleum diesel fuel is

129,500 BTU/gal. The reference data for fuel consumption is obtained from the Generac

Power Systems, Inc. operating data manual for 25, 50, 75, and 100% load at 60 Hz. The

rated output for these loads corresponds to 20, 40, 60, and 80 kW at 2.3, 3.2, 4.3, and 6

gallons per hour, respectively.

On average, the B50 had approximately 35% higher volumetric fuel consumption than

the petroleum diesel. The fuel consumption for 100% biodiesel was about 25% higher

than that of the petroleum diesel. At the lower loadings, B100 and B50 have similar fuel

consumptions; however, at the higher loadings B100 operates with about 10% lower fuel

consumption. Table 3-4 outlines the average fuel consumption results in gallons per

hour. Table 3-5 outlines the average energy consumption in kilojoules per hour. Figure

3-5 illustrates the energy consumption per hour for B0, B50, and B100 over the sampling

loads.

Table 3-4: Average Fuel Consumption for B0, B50, and B100 (gal/hr)

Load Setting Fuel Consumption (gallons/hour)(kW) B0 B50 B100

0 1.05 1.33 1.3825 1.98 2.64 2.6550 3.17 4.38 3.81


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Figure 3-2: Fuel Consumption (gal/hr) for B0, B50, B100, and Manual Reference

0

1

2

3

4

5

6

0 20 40 60 80

Load (kW)

F

uelConsumption(gal/hr)

B0

B50

B100

Ref

Table 3-5: Average Energy Consumption (kJ/hr) for B0, B50, and B100Load Setting Energy Consumption (kJ x 10

5/hour)

(kW) B0 B50 B100

0 1.45 1.85 1.8125 2.71 3.55 3.2950 4.34 5.11 5.0175 5.91 7.10 6.60

Figure 3-3: Energy Consumption (kJ/hr) for B0, B50, and B100

2.00E+05

3.00E+05

4.00E+05

5.00E+05

6.00E+05

7.00E+05

EnergyConsump

tion(kJ/hr)

B0

B50

B100


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On average, the B50 energy consumption was 24% higher than B0 and B100 had on

average only 20% higher energy consumption than the B0 fuel, even though the B100 has

lower energy content than B50. The higher fuel consumption of the biodiesel is not only

due to the lower fuel energy but may also be from a reduction in combustion efficiency.

3.2. Particulate Analysis

The particulate matter, NOx, and carbon monoxide diesel engine emission rates for an

engine rated between 56 kW to 130 kW are outlined in 40 CFR Part 1039, Control of

Emissions from New and In-Use Non-Road Compression Ignition Engines. The

emissions rates of 0.02 g/kW-hr PM, CO 5.0 g/kW-hr, and 0.40 g/kW-hr NOx arerequired by 2014.

3.2.1. Diesel Particulate Matter (PM)

The total PM mass concentration (soluble and insoluble) was determined by gravimetric

method prior to the soluble extraction, with the total mass collected on the filter being

divided by the total sampling volume, corrected to standard temperature and pressure 0C

(273.15 K) and 101.3 kPa (1 atm). Sampling time for all loads was 30 minutes; B0 and

B50 required three filter changes at 75 kW because of increased pressure drop across the

filter. B100 did not require any filter changes in order to sample for the 30 minutes at

any load. At minimum three runs at each load per fuel combination were analyzed.


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Figure 3-4: Quartz fiber filters after dilution sampling with B0 at 0 kW (A), 25 kW

(B), and 50 kW (C) for 30 minutes and at 75 kW (D) for 15 minutes

Figure 3-5: Quartz fiber filters after dilution sampling with B100 at 0 kW (A),

25 kW (B), 50 kW (C), and 75 kW (D) for 30 minutes

Figure 3-6 compares the total diesel particulate matter (PM) concentration (mg/std m3)

for the ultra low-sulfur petroleum diesel (B0) with the B50 blend and B100 fuel. Overall,

A B

C D

A B

C D


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The total PM exhaust concentration for the B100 is higher at all loadings. The highest

concentration for B50 and B100 occurs at 25 kW with the lowest at 0 kW. The lowest

concentration for B0 occurs at 50 kW with the highest at 75 kW with similar

concentrations at 0 and 25 kW loadings.

Figure 3-6: PM Concentration (mg/std m3) in Total Sampling Volume for B0, B50,

and B100 over sampling loads (kW)

0

5

10

15

20

25

30

0 20 40 60 80

Load (kW)

PMConcentration(mg/stdm3)

B0

B50

B100

To determine the emission rate of total PM, the PM concentration over the total sampling

volume by the exhaust gas flow rate yields the emission rate in terms of grams of

emission per hour over each load. Figure 3-7 illustrates the PM emission rate (g/hr) for

B0, B50, and B100 over each load. Figure 3-8 illustrates the emission rate (g/kW-hr) for

B0 B50 and B100 over the sampling loads 25 50 and 75 kW


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Figure 3-7: PM Emission Rate (g/hr) for B0, B50, and B100 over sampling loads

(kW)

0

1

2

3

4

5

6

7

8

0 20 40 60 80

Load (kW)

EmissionRate(g/hr

B0

B50

B100

Figure 3-8: PM Emission Rate (g/kW-hr) for B0, B50, and B100 over sampling loads

25, 50, and 75 kW

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

20 30 40 50 60 70 80

Load (kW)

EmissionRate(g

/kW-hr)

B0

B50

B100


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produced the highest emission rate (g/hr) at 25 kW, in excess of three times as much as

B0. It is important to note that white smoke was continually evident during all trials at 25

kW for B100. White smoke was not apparent during any other runs. White smoke is

generally an indication of the exhaust of water vapor or partially combusted biodiesel due

to the relatively high fuel flow and low combustion temperatures at that power setting.

During the engine start-up, all fuels produced a cloud of black smoke. The black smoke

was darker for the petroleum fuel than was for the biodiesel fuel. The PM emission rate

in g/kW-hr decreased as load increased for B50 and B100. B0 increased in PM emission

rate (g/kW-hr) at the high loading. All fuels exceeded the PM limit of 0.02 g/kW-hr.

In order to further quantify the results, the PM concentration in the exhaust gas, along

with the exhaust gas flow rate, fuel consumption, and the approximate density of the fuel

was utilized to determine the milligram of PM emission per kilogram of fuel consumed.

Figure 3-9 illustrates this emission rate (mg PM/kg fuel consumed) for B0, B50, and

B100 over the loads. At the 0 and 75 kW loading, B50 produces the lowest emission rate

by 6 and 50%, with an increase of 50% at the 25 kW loading. Although it is lower than

B0 at 75 kW by 10%, the B100 produced much higher emission rates for mass of PM

emitted per mass of fuel consumed at the other loadings, with a spike occurring at the 25

kW load. Figure 3-10 shows the emission rate in terms of micrograms of PM emitted per

kilojoules of fuel consumed. Table 3-6 outlines the overall averages for the PM mass


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Figure 3-9: PM Emission Rate (mg emitted mass/kg of fuel consumed) for B0, B50,


0

100

200

300

400

500

600

700

800

9001000

0 20 40 60 80

Load (kW)

mgPM/kgfuelconsumed

B0

B50

B100

Figure 3-10: PM Emission Rate (g emitted mass/kJ of fuel consumed) for B0, B50,


0

5

10

15

20

25

30

0 20 40 60 80Load (kW)

EmissionRate(g/kJ)

B0

B50

B100


48/121

Table 3-6: Average PM Emissions for B0, B50, and B100 over all loadings

Load

Setting

(kW)

PM Conc.,

mg/std m3

Emission

Rate, g/hr

Emission

Rate,

g/kW-hr

Emission Rate,

mg PM

emitted/kg fuelburned

Emission

Rate,

g/kJ

B0 0 6.00 0.59 1.58 0.16 492.3 48.8 10.89 1.0825 6.33 1.01 1.81 0.28 0.072 0.012 301.5 46.3 6.67 1.0650 5.52 1.27 1.88 0.43 0.039 0.009 195.8 45.2 4.33 1.0075 10.21 2.37 3.88 0.90 0.056 0.014 297.6 68.9 6.55 1.53

B50 0 7.78 2.13 2.05 0.56 481.7 131.8 11.40 3.1225 15.85 2.80 4.53 0.80 0.189 0.034 539.3 94.9 12.77 2.2550 8.96 2.97 3.06 1.01 0.060 0.018 220.1 72.9 5.21 0.7775 9.11 1.19 3.48 0.45 0.050 0.007 183.9 21.2 4.33 0.57

B100 0 10.40 1.50 2.74 0.39 595.6 85.9 15.07 2.1725 28.56 0.56 8.17 0.16 0.342 0.007 924.2 18.1 23.38 0.4650 16.77 0.78 5.72 0.26 0.122 0.006 450.1 20.8 11.39 0.5375 12.04 0.61 4.60 0.23 0.073 0.004 274.8 13.9 6.95 0.35

While operating the 1992 non-road diesel test engine generator with single dilution

sampling, results indicated that the biodiesel blends produce more PM (prior to soluble

extraction) than the petroleum diesel and that PM concentration (mg/std m3) increases

with increasing biodiesel concentration at the same loading. Results also indicate that the

biodiesel and biodiesel blend operates the least efficient at the 25 kW loading. The

emission rate (g/kW-hr) decreased as loading increased.

Several studies have also found an increase in PM for biodiesel fuel in comparison to

petroleum diesel fuel.4, 6, 20, 21 A possible explanation may be due to the higher density of

the biodiesel fuel, as the density of fuel is correlated with particulate emissions. An


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Related studies with similar emission rates on comparable engines and sampling methods

may indicate the age of the engine and the absence of control technology may also

contribute to higher PM concentrations. In a related study, an increase in PM and NOx

with a decrease in insoluble PM, hydrocarbon emissions, and PAH emissions was

determined from operating a direct-injection, 52 kW four-cylinder engine on rapeseed

and soybean methyl esters in comparison to petroleum diesel. The sampling method

employed was a double isokinetic dilution tunnel. Particulate matter concentration

increased linearly with increasing biodiesel percentage and the organic insoluble matter

decreased with higher percentages of biodiesel. The rapeseed methyl ester had higher

emission results than the soybean methyl ester, indicating some variability with source oil

and corresponding emissions. The PM emission rates for B0 with and without a catalytic

converter were 2 and 3 g/hr, respectively. For the B100, the PM emission rates with and

without a catalytic converter were 5 and 9.5 g/hr.4 Increased PM concentration and NOx

emissions with lower PAH emissions were also ascertained from a four-cylinder, 52 kW

agriculture tractor diesel engine and 4.2 kW four-stroke direct injection test engine

operating on rapeseed methyl ester. Higher percentages of sampled masses were

extracted from the filters from the biodiesel exhaust than those used for the petroleum

diesel fuel. For the test engine equipped with a catalytic converter operating on rapeseed

methyl ester, the PM emission rate for B0 was 2 g/hr and for B100 was 5 g/hr. 20

Biodiesel is also known to have an effect on rubber parts within the engine.6 Biodiesel


50/121

The increased PM results for the biodiesel fuels could also be attributed to the different

experimental ambient air temperature and humidity conditions. The biodiesel fuel was

tested during elevated ambient temperatures with low relative humidity whereas the ultra-

low sulfur petroleum fuel and B50 blend tests were completed during mild ambient

temperature and relative humidity levels. Humidity and temperature may influence the

nature of combustion. Sampling parameters, such as temperature consistency across the

filter, may also influence the results.

The age of the engine, type of source oil, sampling method, environmental conditions,

and control technology present on the engine all can affect the overall emission from the

biodiesel and petroleum fuels. In a related dilution sampling research on a 2003 non-road

diesel engine with current emission control devices, significant reductions in PM and CO

with a slight increase in NOx were found from operating with soybean methyl ester

biodiesel and pure methyl esters, methyl oleate, methyl palmitate, and methyl laurate.

The PM emission rate while operating on petroleum diesel was 0.15 g/kW-hr and while

operating on the methyl soyate was 0.03 g/kW-hr.23

3.3. Exhaust Gas Analysis

Temperature, carbon monoxide (CO), carbon dioxide, oxides of nitrogen (NOx), and

percent oxygen in the exhaust stream were measured utilizing the Testo Gas Analyzer.

3 3 1 T t


51/121

3.3.1 Temperature

The temperature of the engine exhaust was monitored continuously over the course of the

experiments. Figure 3-11 illustrates the average exhaust temperature (C) recorded for

each fuel over the varying loads. Ambient temperatures greatly influenced exhaust

temperatures. The generator engine was operated on the B100 during elevated ambient

temperatures, approximately 35C, in comparison to the B50 at 27C and B0 at 25C

ambient conditions.

Figure 3-11: Temperature Profile of exhaust stream (C) for B0, B50, and B100 over

sampling loads (kW)

100

150

200

250

300

350

400

0 20 40 60 80

Load (kW)

ExhaustS

treamTemperature(C)

B0

B50

B100

Exhaust temperature increased linearly with increasing loading. The temperatures of the

exhaust stream for B50 and B0 were extremely close for the higher loadings and the B50

3 3 2 C b M id


52/121

3.3.2. Carbon Monoxide

Increasing loads on diesel engines leads to an increase in the combustion temperature and

efficiency, resulting in lower carbon monoxide (CO) emissions when compared to lower

loading conditions. Soot (the insoluble fraction of the particulate matter) is a product of

incomplete combustion, which usually increases directly with fuel consumption.

Figure 3-12: Carbon Monoxide (ppm) in the exhaust stream for B0, B50, and B100over sampling loads (kW)

0

50

100

150

200

250

300

0 20 40 60 80

Load (kW)

CO(ppm B0

B50

B100

Figure 3-12 illustrates that the biodiesel and biodiesel blend produced lower CO levels

than the B0. B100 produced the most dramatic decrease in CO at the lowest and highest

loadings, resulting in a 60% decrease at 0 kW and an 85% decrease at 75 kW from the

B0, although the low CO concentrations at the high loading falls within the accuracy of

the instrument (10 ppm).

3 3 3 Carbon Dioxide


53/121

3.3.3. Carbon Dioxide

As the load increases with higher temperatures and higher fuel usage, more of the fuels

carbon is oxidized to carbon dioxide (CO2), and carbon dioxide increases with increased

loads. Complete combustion results in all carbon in the fuel to be converted to carbon

dioxide, whereas carbon monoxide is a result of incomplete combustion. The increase in

carbon dioxide for biodiesel over the petroleum diesel is shown in Figure 3-13. B50

resulted in about a 20% increase in CO2 emissions when compared to B0 and B100

resulted in an average 30% increase compared to B0.

Figure 3-13: Carbon Dioxide (%) in exhaust stream for B0, B50, and B100 over

sampling loads (kW)

0

1

2

3

4

5

6

7

8

9

0 20 40 60 80

Load (kW)

CO2(%) B0

B50

B100

3.3.4. Oxides of Nitrogen (NOx)

The 2002 U.S. EPA study established that NOx emissions for biodiesel and biodiesel

temperatures which resulted in slightly higher NO NO emissions were lower for B50


54/121

temperatures, which resulted in slightly higher NOx. NOx emissions were lower for B50

at 0 kW when compared to B0, but conversely were about 35% higher at the highest load.

B100 resulted in NOx emissions about 25% higher than B0 at 0 and 50 kW and about

45% higher at 25 and 75 kW.

Figure 3-14: Oxides of Nitrogen (ppm) in exhaust stream for B0, B50, and B100 over

sampling loads (kW)

0

200

400

600

800

1000

1200

1400

1600

1800

0 20 40 60 80

Load (kW)

NOx

(ppm B0

B50

B100

3.3.5. Percent Oxygen

Less oxygen and more carbon dioxide for the biodiesel and biodiesel blend indicates a

more complete combustion, which is consistent with the CO results. Figure 3-15 shows

that the biodiesels produced about a 7% decrease in the percent oxygen in the exhaust

stream when compared to B0.

Figure 3-15: Percent Oxygen in exhaust stream for B0, B50, and B100 over


55/121

Figure 3 15: Percent Oxygen in exhaust stream for B0, B50, and B100 over

sampling loads (kW)

10

12

14

16

18

20

22

0 20 40 60 80

Load (kW)

O2(%) B0

B50

B100

Table 3-7 outlines the averaged results for the gaseous emissions measured with the

Testo Gas Analyzer. The data listed includes the exhaust temperature (C), carbon

monoxide (ppm), percent carbon dioxide, NOx (ppm), and percent oxygen.

Table 3-7: Average Gaseous Emissions for B0, B50, and B100 over all loadings

Load

Setting

(kW)

Exhaust

Temp. C

CO, ppm CO2, % NOx, ppm O2, %

B0 0 120 1.5 250 30 1.76 0.28 227 7 19.5 0.5325 183 9.8 138 12 3.28 0.03 440 28 16.6 0.0950 258 5.4 70 5 5.54 0.07 876 24 13.8 0.06

75 311 6.1 31 5.5 5.92 0.37 1079 95 12.1 1.49B50 0 131 2 191 14.5 2.11 0.03 200 5 18.1 0.03

25 196 4.9 132 8.5 3.96 0.11 512 30.5 16.3 1.0350 260 0.6 63 2.5 5.64 0.08 966 19.5 13.4 0.0575 310 7 2 17 3 7 16 1550 11 4 0 02

3.4. Chemical Composition Analysis


56/121

p y

3.4.1. Soluble Fractions of PM

The soluble fraction or percent of volatile organics extracted is determined from the

collected PM mass on the quartz fiber filters before and after extraction. The organics

were extracted from the filters with dichloromethane (DCM) in order to perform the

analysis. Figure 3-16 illustrates the results of the extraction percentages. The percent

organics extracted was consistently higher for the B100 and B50 than for the B0. The

organics extracted were highest at light engine loads when combustion temperatures are

lower. The organic fraction of B50 is higher than for petroleum, and B100 is higher than

B50, meaning that combustion of biodiesel and the biodiesel blend emit higher unburned

hydrocarbons. Even though the emitted volatile concentrations were higher for biodiesel,

the amount of soot emitted is higher for the petroleum diesel.

Figure 3-16: Percent Organics Extracted for B0, B50, and B100 over sampling loads

(kW)

60

65

70

75

80

85

90

95

100

Percen

tSoluble(%)

B0

B50

B100

Table 3-8: Percent Organics Extracted for GC/MS analysis of B0, B50, and B100 at


57/121

g y , ,

each sampling load (kW)

Load Setting Percent Organic Extracted

(kW) B0 B50 B1000 93.6 1.9 95.3 2.8 93.825 91.7 1.5 95.8 1.5 95.5 1.350 77.8 6.1 92.1 4.7 94.9 0.175 65.4 1.7 81.3 7.2 76.9 0.4

Table 3-9 lists the average collected mass (mg) for each fuel at the various loads. This

constitutes the mass dissolved in solvent utilized for subsequent thermal analysis.

Table 3-9: Total amount of mass collected (mg) for GC/MS analysis of B0, B50, and

B100 at each sampling load (kW)

Load Setting Collected Mass (mg)

(kW) B0 B50 B100

0 41.6 2.3 56.8 15.7 57.825 38.5 1.8 112.5 20.7 178.3 0.850 31.1 7.6 48.2 3.9 100.2 1.375 10.7 1.0 18.5 3.1 57.2 0.1

The percentage in total extracted organic PM mass for each category decreases at the

higher loadings, which corresponds to an increase in the insoluble fraction (soot).

Biodiesel produced lower concentrations of emitted insoluble PM, but a larger amount of

organic PM. The soluble gaseous emissions were determined from the combined

extraction of the XAD adsorbent and polyurethane foams.

3.4.2. n-Alkanes

Normal alkanes account for a large fraction of the diesel fuel and the identifiable portion

Number 31214. The following table, Table 3-10, lists the components, elution order, and


58/121

chemical properties of the n-alkane standard, as listed from Restek Corporation.

Table 3-10: n-Alkane standard elution order and chemical properties

Elution

Order

Compound Formula Molecular

Weight

(g/gmol)

Boiling

Point

(C)

Melting

Point

(C)

Density

(g/cm3)

1 (C10) Decane C10H22 142.28 174 -30 0.732 (C11) Undecane C11H24 156.31 196 -26 0.74

3 (C12) Dodecane C12H26 170.33 216 -9.6 0.754 (C13) Tridecane C13H28 184.36 234 -5 0.765 (C14) Tetradecane C14H30 198.39 253 5.5 0.766 (C15) Pentadecane C15H32 212.41 270 9 0.777 (C16) Hexadecane C16H34 226.44 287 18 0.778 (C17) Heptadecane C17H36 240.47 302 21 0.789 (C18) Octadecane C18H38 254.49 317 28 0.78

10 (C19) Nonadecane C19H40 268.52 330 33 0.7911 (C20) Eicosane C20H42 282.55 220 36 N/A12 (C21) Heneicosane C21H44 296.57 100 40 N/A13 (C22) Docosane C22H46 310.60 369 44 0.7814 (C23) Tricosane C23H48 324.63 200 47 N/A15 (C24) Tetracosane C24H50 338.65 391 50 N/A16 (C25) Pentacosane C25H52 352.68 170 55 N/A

According to the World Health Organization, petroleum diesel fuel comprises of

approximately 65% n-alkanes and about 2 to 30% aromatics.3 Figure 3-17 illustrates the

n-alkane distribution (concentration percentage) for ULS petroleum diesel and B50

soybean methyl ester fuel utilized in this research. The petroleum fuel demonstrates a

bell-shaped distribution from C10 (docane) to C23 (tricosane), with the most abundant

occurring at C16 (hexadecane) to C21 (heneicosane). Since there are no alkanes present in

amount of settling that occurs because of the differences in density and viscosity for the


59/121

two fuels.

Figure 3-17: n-Alkanes Concentration (%) in B0 and B50 Fuel

0

2

4

6

8

10

12

14

16

18

decan

e

undec

ane

dodec

ane

tridecan

e

tetra

decan

e

pentadec

ane

hexa

decan

e

heptadec

ane

octadec

ane

nona

decan

e

eicos

ane

heneicos

ane

docos

ane

tricosan

e

tetra

cosan

e

pentacos

ane

Concentration

(%)

B0

B50

For all fuel types, the n-alkane concentration in both the particulate and gas phase was

highest for the B0 fuel. The PM and gaseous compound concentration over the sampling

volume (g/std m3) and emission rate (mg/hr) was highest at the 25 kW loading, except

B100 gas phase which experienced the highest n-alkane concentration emission at 0 kW.

Higher concentrations were emitted at the 0 and 25 kW load than 50 and 75 kW though

fuel consumption rate increases linearly with load. The increase at 25 kW corresponds to

the increase in mass collected for analysis. The lowest mass collected was at 75 kW,

which resulted in the lowest concentrations In addition as the load increases unburned

To quantify the results further, the emission rate is expressed in terms of milligram of


60/121

compound emitted per kilogram of fuel consumed. The emission rate is also expressed in

terms of nanogram of compound emitted per kilojoules of fuel consumed. For B0, these

emission rates are the highest for each fuel type with a maximum in both the particulate

phase and gaseous phase at 0 kW. For B50 and B100, the highest in the PM occurred at

25 kW and in the gaseous phase, 0 kW emitted the highest amount of n-alkane per

amount of fuel consumed.

As exhaust gas temperatures increase with load, the higher combustion temperatures

reduce the unburned hydrocarbons due to higher combustion efficiency. For all fuel

types, the gas phase concentrations were higher than the particle phase concentration.

Lighter alkanes are present in the gas phase as opposed to the heavier alkanes found in

the particle phase. There is a shift to heavier n-alkanes from diesel fuel to PM, as the

result of the combustion process, as shorter-chained alkanes are more likely to undergo

complete combustion than heavier alkanes.3 Figure 3-18 through Figure 3-21 shows the

n-alkane distributions for B0 in the particulate phase.


(kW)


61/121

(kW)

0

20

40

60

80

100

120

deca

ne

unde

cane

dode

cane

tride

cane

tetra

deca

ne

pentad

ecan

e

hexa

deca

ne

heptad

ecan

e

octade

cane

nona

deca

ne

eico

sane

heneic

osan

e

doco

sane

trico

sane

tetra

cosane

pentac

osan

e

C

oncentration(g/m

3)

0 kW

25 kW

50 kW

75 kW

Figure 3-19: n-Alkane PM Emission Rate (mg/hr) for B0 over sampling loads (kW)

0

5

10

15

20

25

30

35

40

deca

ne

und

ecan

e

dod

ecan

e

trid

ecan

e

tetrade

cane

pentade

cane

hexa

deca

ne

heptade

cane

octade

cane

nonade

cane

eic

osan

e

heneic

osan

e

doc

osan

e

tric

osan

e

tetraco

sane

pentaco

sane

EmissionRate(mg/hr)

0 kW

25 kW

50 kW

75 kW

Figure 3-20: n-Alkane PM Emission Rate (mg emitted compound/kg fuel consumed)

for B0 over sampling loads (kW)


62/121


0

1

2

3

4

5

6

7

89

deca

ne

unde

cane

dode

cane

tride

cane

tetra

deca

ne

pentad

ecan

e

hexa

deca

ne

heptad

ecan

e

octade

cane

nona

deca

ne

eico

sane

heneic

osan

e

doco

sane

trico

sane

tetra

cosane

pentac

osan

e

mgCompound/kgfuelconsumed

0 kW

25 kW

50 kW

75 kW

Figure 3-21: n-Alkane PM Emission Rate (ng emitted compound/kJ fuel consumed)


0

20

40

60

80

100

120140

160

180

200

decane

unde

cane

dode

cane

tride

cane

tetra

decane

pentad

ecane

hexa

decane

heptad

ecane

octade

cane

nona

decane

eico

sane

heneic

osane

doco

sane

trico

sane

tetra

cosane

pentac

osane

EmissionRate(n

g/kJ)

0 kW

25 kW

50 kW

75 kW


sampling loads (kW)


63/121

sampling loads (kW)

0

100

200

300

400

500

600

700800

deca

ne

unde

cane

dode

cane

tride

cane

tetra

deca

ne

pentad

ecan

e

hexa

deca

ne

heptad

ecan

e

octade

cane

nona

deca

ne

eico

sane

heneic

osan

e

doco

sane

trico

sane

tetra

cosane

pentac

osan

e

Concentration(g/m

3)

0 kW

25 kW

50 kW

75 kW


(kW)

0

50

100

150

200

250

deca

ne

und

ecan

e

dod

ecan

e

trid

ecan

e

tetra

deca

ne

pentade

cane

hexad

ecan

e

heptade

cane

octade

cane

nonade

cane

eic

osan

e

heneic

osan

e

doc

osan

e

tric

osan

e

tetra

cosane

pentaco

sane

EmissionRate(mg/hr)

0 kW

25 kW50 kW

75 kW

Figure 3-24: n-Alkane Gaseous Emission Rate (mg emitted compound/kg fuel

consumed) for B0 over sampling loads (kW)


64/121


0

5

10

15

20

25

30

3540

deca

ne

unde

cane

dode

cane

tride

cane

tetra

deca

ne

pentad

ecan

e

hexa

deca

ne

heptad

ecan

e

octade

cane

nona

deca

ne

eico

sane

heneic

osan

e

doco

sane

trico

sane

tetra

cosane

pentac

osan

e

mgCompound/kgfuelconsumed

0 kW

25 kW

50 kW

75 kW

Figure 3-25: n-Alkane Gaseous Emission Rate (ng emitted compound/kJ fuel


0

100

200

300

400

500

600

700

800

900

deca

ne

unde

cane

dode

cane

tride

cane

tetrad

ecan

e

pentad

ecan

e

hexad

ecan

e

heptad

ecan

e

octad

ecan

e

nonad

ecan

e

eico

sane

henei

cosane

doco

sane

trico

sane

tetracos

ane

pentac

osan

e

EmissionRate(ng/kJ)

0 kW

25 kW

50 kW

75 kW

peaks are not separated. The n-alkane concentration and emission rate in the PM for B50


65/121

is about half that of the B0 except at the 25 kW loading where the decrease is only about

25%, which agrees with the reduction in n-alkane from the biodiesel fuel.


(kW)

0

1020

30

40

50

60

70

80

90100

deca

ne

unde

cane

dode

cane

tride

cane

tetra

deca

ne

pentad

ecan

e

hexa

deca

ne

heptad

ecan

e

octade

cane

nona

deca

ne

eico

sane

heneic

osan

e

doco

sane

trico

sane

tetra

cosane

pentac

osan

e

C

oncentration(g/m

3)

0 kW

25 kW

50 kW

75 kW

Figure 3-27: n-Alkane PM Emission Rate (mg/hr) for B50 over sampling loads (kW)

5

10

15

20

25

30

EmissionR

ate(mg/hr)

0 kW

25 kW

50 kW

75 kW

Figure 3-28: n-Alkane PM Emission Rate (mg emitted compound/kg fuel consumed)



66/121

p g ( )

0

0.5

1

1.5

2

2.5

3

3.5

deca

ne

unde

cane

dode

cane

tride

cane

tetra

deca

ne

pentad

ecan

e

hexa

deca

ne

heptad

ecan

e

octade

cane

nona

deca

ne

eico

sane

heneic

osan

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Air Pollutants From Biodiesel Fuel Usage

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