2001 atmos. environ. zervas e. emission of specific pollutants from a compression ignition engine....

7/30/2019 2001 Atmos. Environ. Zervas E. Emission of Specific Pollutants From a Compression Ignition Engine. Influence of F

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*Corresponding author. Present address: Renault - 66123

- CTL L26 1 46, 1, AlleHe Cornuel, F - 91510 Lardy, France. Tel.:

#331-69-27-84-87; fax:#331-69-27-00-49.

E-mail address: [email protected] (E. Zervas).

Atmospheric Environment 35 (2001) 1301}1306

Emission of speci"c pollutants from a compressionignition engine. In#uence of fuel hydrotreatment and fuel/air

equivalence ratio

E. Zervas*, X. Montagne, J. Lahaye

Institut Franc7 ais du Pe&trole, 1 et 4 avenue du Bois Pre&au, F-92500 Rueil-Malmaison cedex, France

Institut de Chimie des Surfaces et Interfaces, 15 rue Jean Starcky, F-68057 Mulhouse cedex, France

Received 19 April 2000; received in revised form 17 July 2000; accepted 20 July 2000

Abstract

A compression ignition engine is used for the study of the fuel (one reference and one hydrotreated) and the fuel/air

equivalence ratio in#uence on the exhaust emissions of speci"c pollutants. Under the experimental conditions used, seven

hydrocarbons, nine aldehydes and three organic acids are detected in the exhaust gas. No alcohols are detected under

these conditions, indicating that these compounds are emitted only if they (or probably other oxygenated compounds)

are introduced in the fuel. Fuel hydrotreatment decreases most of the exhaust pollutants, the four toxics and also the

quantity of the ozone that could be formed from the exhaust gas. It also changes the composition of exhaust gas: it

increases the proportion of methane, benzene, formaldehyde, acetaldehyde, acroleine, and propionic acid, while it

decreases the proportion of all other pollutants detected. Fuel/air equivalence ratio also decreases most of the exhaust

emissions, the emission of the total toxics and the quantity of the ozone that could be formed. It also changes the

proportion of each pollutant in exhaust gas: the percentages of methane, benzene, acetone and acetic acid increase, whilethose of the other pollutants detected decrease. The majority of the speci"c pollutants detected corresponds to organic

acids, followed by hydrocarbons and aldehydes. 2001 Elsevier Science Ltd. All rights reserved.

Keywords: Aldehydes; Compression ignition engines; Hydrocarbons; Organic acids; Ozone

1. Introduction

Since 1 January 2000, the Euro3 emission regulations are

applied in new vehicles of EU member states. These regula-

tions divide almost by two the limits of CI engines for thefour regulated pollutants (CO, NO

V, NO

V#HC, PM).

Although these regulations concern total HC exhaust emis-

sions, all exhaust individual hydrocarbons do not have the

same ozone forming potential or the same e!ects on the

human health; benzene and 1,3 butadiene are known

as toxic pollutants. The study of individual hydrocarbons

exhaust emissions are sometimes necessary to complete

information about total hydrocarbons exhaust emissions.

Aldehydes and ketones are believed to contribute

to the characteristic smell of CI engines exhaust gas, to

participate in the formation of atmospheric ozone, andtwo of them (formaldehyde and acetaldehyde) are known

as toxic pollutants. Some articles present the in#uence of

the fuel and the engine running conditions on the emis-

sions of these pollutants (Bertoli et al., 1993; Montagne et

al., 1991) and others study their atmospheric distribution

(Anderson et al., 1996; Possanzini et al., 1996 and many

others).

Alcohols and other oxygenates are usually added to

the fuel to decrease CO, NOV

and particulate matter

emissions, but they can increase the emission of formal-

dehyde or decrease those of the other aldehydes (Lipari

and Swarin, 1982; Liotta and Montalvo, 1993).

1352-2310/01/$- see front matter 2001 Elsevier Science Ltd. All rights reserved.

PII: S 1 3 5 2 - 2 3 1 0 ( 0 0 ) 0 0 3 9 0 - 3


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Table 1

Engine and running conditions used

Engine

Type Peugeot XUD9

Prechamber Ricardo Comet V

Cylinders 4Displacement (cm) 1905

Bore (mm) 83

Stroke (mm) 88

Compression ratio 23 : 1

Injection pump BOSCH VER272 type 520

Opening pressure (bar) 130

Running conditions

Engine speed (RPM) and BMEP 2500, 8

Torque (N m) 21

Injection timing 63 BTDC

Coolant temperature (K) 358

Lubri"ant temperature (K) 368

Intake air temperature (K) 313Intake air pressure (bar) 0.993

Fuel/air equivalence ratio 0.24}0.50

Table 2

Main characteristics of the fuels used

Fuel SR HDT2

Density at 288 K (kg m\) 837.2 832.3

Cin. viscosity at 293 K (mm s\) 5.60 5.56

Distillation (3C)

Initial point 482 473

5% 513 508

95% 610 603

Final point 626 621

Chemical analysis (wt%)

Para$ns 46.1 47.5

Naphtenes 32 33.4

Non cond. Naphtenes 22.5 22.3

Condensed Naphtenes 9.5 11.1

Aromatics 21.9 19.1

Mono-aromatics 12.1 16.1

Di-aromatics 9.3 2.9

Tri-aromatics 0.3 0.1

Sulphured aromatics 0.2 *

Sulphur 0.055 0.047

Cetane number 53.8 56

Organic acids are also found in the exhaust gas. They

contribute to acid rain formation (Lawrence and Kou-

trakis, 1994), and many articles study the formation and

reactions of atmospheric organic acids (Chebbi and

Carlier, 1996; Lawrence and Koutrakis, 1994; Souza

et al., 1999 and many others). Some authors study the

exhaust emissions of these pollutants (Kawamura et al.(1985) for a comparison between atmospheric, engine oil

and exhaust gas acids, Kawamura and Kaplan (1987) for

the dicarboxylic organic acids emissions from compres-

sion ignition engines, Zervas et al. (1999a) for the correla-

tions between gasoline composition and exhaust acids

emissions from an SI engine, and Zervas and Tazerout

(2000) for the emission of formic acid from a natural gas

feed SI engine).

Fuel and engine operating conditions in#uence

the speci"c pollutants emissions and their control can

help to decrease the engine out and tailpipe emissions.

This work presents the emission of individual hydrocar-bons, aldehydes, alcohols and organic acids from a

compression ignition engine fed with two di!erent fuels

(a commercial and an hydrotreated one). The in#uence

of the fuel and the fuel/air equivalence ratio on the

emission of these pollutants, on the emission of total

toxics and on the ozone forming potential is presented

and discussed.

2. Experimental section

2.1. Engine and fuels used

The engine used in this work is a PSA XUD9 four-

stroke cycle Diesel Engine. Table 1 presents the main

characteristics of this engine and the experiment running

conditions. Due to low emissions, every experimental

point is doubled and the average value of each pollutant

is taken into account. Table 2 presents the main charac-

teristics of the two fuels used, the reference (SR) and the

hydrotreated (HDT2).

2.2. Exhaust gas analysis

The analysed exhaust gas components are: CO andCO

using nondispersive IR, O

using paramagnetism

and total hydrocarbons by FID. Particulate matter is

collected on a "lter and a balance determines the total

mass. The individual hydrocarbons are analysed on line

by GC/FID. Alcohols are collected in deionised water

and analysed by GC/FID, following the procedure de-

scribed by Siegel et al. (1993) and Smith (1985). Al-

dehydes and ketones are collected in an acidi"ed DNPH

solution and analysed by HPLC/UV, following the pro-

cedure described by Lipari and Swarin (1982) and

Smith (1985). Organic acids are collected in deionised

water and analysed by two methods: ionic chromatogra-

phy/conductimetric detection for the analysis of

formic acid and GC/FID for the analysis of the heavier

acids, following the procedure presented elsewhere

(Zervas et al., 1999b). More details about these

analytical methods can be found elsewhere (Zervas et al.,

1999a, b).

1302 E. Zervas et al. /Atmospheric Environment 35 (2001) 1301}1306


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Fig. 1. In#uence of fuel/air equivalence ratio and fuel on CO

,

CO, HC and PM emissions.

2.3. Repeatability tests

Five identical tests are performed using the SR fuel at

the fuel/equivalence ratio of 0.5 to evaluate the repeata-

bility of engine and of analytical methods.

3. Results and discussion

3.1. Analysis

The following compounds are detected without inter-

ference in the exhaust gas: seven hydrocarbons: methane,

ethylene, propylene, acetylene, 1-butene, 1,3-butadiene

and benzene; ten aldehydes: formaldehyde, acetaldehyde,

acroleine, acetone, propionaldehyde, crotonaldehyde,

methacroleine, butyraldehyde#methylethylketone and

benzaldehyde (the column used cannot separate methyl-

ethylketone and n-butyraldehyde); no alcohol, even fora collection time of 2 h, indicating that these compounds

are emitted only if they are introduced in the fuel (or

probably after the introduction of an oxygenate com-

pound in the fuel); three organic acids: formic, acetic and

propionic acid.

3.2. Repeatability tests

The relative standard deviation of the "ve identical

tests is less than 2% for the CO and CO

emission, 6%

for the particulate matter, from 6 to 12% for the detected

individual hydrocarbons and from 5 to 20% for thealdehydes and organic acids presented here (the heavy

aldehydes show more dispersion due to low concentra-

tion). In these tests, su$cient duration is used for the

aldehydes and organic acids collection, to avoid higher

dispersions due to low quantities collected.

3.3. Emissions of regulated pollutants

Fig. 1 presents the emissions of CO, CO

, total HC

and particulate matter as a function of fuel and fuel/air

equivalence ratio used. Fuel/air equivalence ratio (in the

range 0.24}0.5) increases the emission of CO , becauseof the increased fuel consumption, and the emission of

particulate matter, due to increased fuel injected; the

emissions of HC and CO decrease due to the decrease of

ignition delay (Heywood, 1988; Stone, 1992). Hydro-

genated fuel decreases all these emissions (Bertoli et al.,

1993; Martin and Bigeard, 1992; Montagne, 1991;

Ullman, 1989). Our tests show a decrease of 3}7% for

the CO

, 6}18% for the CO, 15}22% for the total HC

and 7}13% for the particulate matter. All results present-

ed in Fig. 1 are in accordance with those reported in

literature and help to validate those of the speci"c pollu-

tants.

3.4. Emission of individual hydrocarbons

The seven individual hydrocarbons detected in

the exhaust gas are in quite low concentrations: meth-

ane: 2}4.6 ppmv, ethylene: 1.2}5.1ppmv, acetylene:

0.4}1.2 ppmv, propylene: 0.2}0.8 ppmv, 1-butene:

0}0.13 ppmv, 1,3 butadiene: 0.07}0.27ppmv, benzene:

0.07}0.17ppmv. Exhaust hydrocarbons represent only

24}39% (depending on the fuel and fuel/air equivalence

ratio) of the total speci"c pollutants detected (HC, al-

dehydes, organic acids).

All individual hydrocarbons decrease with fuel/air

equivalence ratio, as total HC do. Fuel hydrotreatment

also decreases the emissions of individual hydrocarbons

up to 30% (depending on the hydrocarbon and the

fuel/air equivalence ratio) compared to the reference fuel.

One hydrocarbon, 1-butene, which is detected in the

exhaust gas of the reference fuel in concentrations of

0.05}0.13ppmv, is below the detection limits in the

exhaust gas of the hydrotreated one.

The use of a hydrogenated fuel decreases the HC

emissions, it also changes their distribution. Fig. 2 pres-

ents the percentage of four hydrocarbons (expressed asppmC of each hydrocarbon over the ppmC of the total

emitted HC): the two major ones, methane and ethylene

(which represent more than the half of total hydrocar-

bons), and the two toxic ones, 1,3-butadiene and benzene,

as a function of the fuel and the fuel/air equivalence ratio

used. Fuel/air equivalence ratio increases the percentage

of methane and benzene in total exhaust hydrocarbons

decreasing that of all the other hydrocarbons detected.

This is explained by the increasing temperature of the

higher fuel/air equivalence ratios and the higher resist-

ance of methane and benzene to oxidation than the other

exhaust hydrocarbons. The hydrotreated fuel produces

E. Zervas et al. /Atmospheric Environment 35 (2001) 1301}1306 1303


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Fig. 2. In#uence of fuel/air equivalence ratio and fuel on thepercentage of methane, ethylene, 1,3 butadiene and benzene

(based on the total number of carbons).

Fig. 3. Emission of formaldehyde, acetaldehyde, acetone andacroleine. In#uence of fuel/air equivalence ratio and fuel on

exhaust emissions and percentage of each aldehyde over the

total aldehydes emission.

the same e!ect: an increase of methane and benzene

proportion and a decrease of all the others. This phenom-

enon indicates that fuel hydrotreatment favours the oxi-

dation of hydrocarbons (this is also the reason for the

decrease of total HC emissions), but the hydrotreated fuel

exhaust gas is relatively composed more of toxic com-

pounds (benzene) or more di$cult to treat with a cata-

lytic converter (methane). It must be noted that even the

percentages of methane and benzene in total exhaust HC

of the hydrotreated fuel are increased, the total methane

and benzene emissions of this fuel decreased compared to

those of the reference one.

3.5. Emission of aldehydes and ketones

Fig. 3 presents the in#uence of fuel/air equivalence

ratio on the emission of the four most important

aldehydes (the others are found in exhaust gas in concen-

tration below 0.1 ppmv), where it is shown that most of

these pollutants concentration decreases with fuel/air

equivalence ratio (within the limits of 0.24 to 0.5), exceptthat of acetone that increases (only in the case of the

reference fuel, this pollutant is not detected in the case of

the hydroteated one). The in#uence of fuel/air equiva-

lence ratio is a complex phenomenon: the formation of

aldehydes from hydrocarbons and their further oxidation

depend on the species in the combustion chamber, the

temperature and the time spent under these conditions;

these factors in#uence their "nal concentration in

exhaust gas.

Fuel hydrotreatment decreases the exhaust aldehydes

(Bertoli et al., 1993), up to 80% in our study. The concen-

tration of some aldehydes (acetone and propionaldehyde)

is found below the detection limits in the case of the

HDT2 fuel.

Fuel/air equivalence ratio decreases the percentage of

most aldehydes in exhaust gases except acetone and

propionaldehyde for the SR fuel and crotonaldehyde and

methacroleine for the HDT2 one. On the other hand, fuel

hydrotreatment increases the proportion of formalde-

hyde, acetaldehyde (the two toxics), and also that of

acroleine, methacroleine and crotonaldehyde, while it

decreases the percentage of the others. Fig. 3 presents

also the proportion of formaldehyde, acetaldehyde,

acetone and acroleine. The other aldehydes detected are

not presented in this "gure because their points are very

scattered due to low emissions.

Exhaust aldehydes represent 8}16% of the total speci-

"c pollutants detected. This corresponds to one-third to

half of the hydrocarbons quantity.

3.6. Emission of organic acids

The exhaust concentration of organic acids decreases

with fuel/air equivalence ratio (Fig. 4). A correlation

between the exhaust concentration of organic acids and

exhaust temperature and oxygen concentration is

already reported in the case of spark ignition engines

or burner experiments (Zervas et al., 1999a, b; Zervas and

Tazerout, 2000). The exhaust concentration of these

pollutants increases with the concentration of exhaust

oxygen and the decrease in exhaust temperature. As

exhaust temperature and oxygen concentration decreases

with fuel/air equivalence ratio, these results are con-

"rmed in the case of a CI engine exhaust gas (Fig. 5).



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Fig. 4. Emission of formic, acetic and propionic acid. In#uenceof fuel/air equivalence ratio and fuel on exhaust emissions and

percentage of each acid over the total acids emissions.

Fig. 5. In#uence of exhaust temperature and oxygen on the

formic, acetic and propionic acid exhaust emissions.

Fig. 6. Total toxics and quantity of ozone could be formed bythe exhaust of the two fuels as a function of the fuel/air equiva-

lence ratio.

Fuel hydrotreatment decreases the concentration offormic and acetic acids but increases that of the propionic

one. This con"rms that aromatic hydrocarbons are dir-

ectly responsible for the propionic acid formation

(Zervas et al., 1999a); the hydrotreated fuel contains

about 4% more monoaromatics (16.1% instead of 12.1%

for the SR fuel) and produces 30}100% more propionic

acid.

Fuel/air equivalence ratio increases the proportion of

acetic acid, while it decreases that of the other two,

indicating that formic and propionic acids are more

sensitive to the variations of exhaust temperature and

oxygen concentration than acetic acid. As hydrotreated

fuel increases the emissions of propionic acid, it also

increases its percentage, while it decreases those of formic

and acetic acids (Fig. 4). This last result comes from the

increased content of aromatics of the hydrotreated fuel.

Exhaust organic acids represent more than half of the

total speci"c pollutants detected (53}60%, mainly com-

posed from acetic acid). This high percentage indicates

that organic acids are probably not formed during the

combustion process, but after the oxidation of other

products during the cooling phase of exhaust gas.

3.7. Emissions of toxic pollutants and ozone-forming

potential

Fig. 6 presents the total emission of the four toxic

pollutants (benzene, 1,3-butadiene, formaldehyde and

acetaldehyde) for both fuels as a function of the fuel/air

equivalence ratio. One can see that total toxics concen-

tration decreases with fuel hydrotreatment and with

fuel/air equivalence ratio.

The ozone quantity that could be formed from the

exhaust gas of the reference and hydrotreated fuel, forevery fuel/air equivalence ratio studied, is also presented

in the Fig. 6. This quantity decreases with the fuel/air

equivalence ratio as the unburned hydrocarbons' emis-

sions decrease. Fuel hydrotreatment has also a bene"t

e!ect, as this fuel decreases most of the exhaust gas

pollutants.

4. Conclusions

No alcohols are detected in the exhaust gas under

the experimental conditions used, indicating that these

E. Zervas et al. /Atmospheric Environment 35 (2001) 1301}1306 1305


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compounds are emitted only if an oxygenated compound

is introduced in the fuel.

Fuel/air equivalence ratio decreases the hydrocarbons,

most of the aldehydes and organic acids exhaust emis-

sions. It also decreases the total emissions of toxics and

the quantity of ozone that could be formed. The propor-

tion of each pollutant in exhaust gas changes with fuel/airequivalence ratio: those of methane and benzene increase

while that of the other HC decreases; those of acetone

and acetic acid increase while those of the other

aldehydes and organic acids decrease.

Fuel hydrotreatment decreases most of the exhaust

pollutants, the total emissions of toxic pollutants and

also the quantity of the ozone that could be formed.

More precisely, it decreases all hydrocarbons, aldehydes

(except methacroleine) and organic acids' (except

propionic acid) exhaust emissions. It also changes the

composition of exhaust gas: in the case of hydrocarbons,

it increases the percentage of methane and benzene, in thecase of aldehydes, that of formaldehyde, acetaldehyde

and acroleine, and in the case of organic acids, that of

propionic acid, while it decreases the percentage of all the

other detected pollutants.

The majority of the emissions of the speci"c pollutants

detected corresponds to organic acids (53}60%), fol-

lowed by HC (24}39%) and aldehydes (8}16%).

References

Anderson, L.G., Lanning, J.A., Barrel, R., Miyagishima, J.,

Jones, R.H., Wolfe, P., 1996. Sources and sinks of formalde-

hyde and acetaldehyde: an analysis of Denver's ambient

concentration data. Atmospheric Environment 30 (12),

2112}2123.

Bertoli, C., Del Giacomo, N., Iorio, B., Prati, M.V., 1993. The

in#uence fuel composition on particulate emissions of DI

Diesel Engines. SAE Technical Paper Series 932733.

Chebbi, A., Carlier, P., 1996. Carboxylic acids in the tropo-

sphere, occurrence, sources and sinks: a review. Atmospheric

Environment 30 (24), 4233}4249.

Heywood, J.B., 1988. Internal Combustion Engine Funda-

mentals. McGraw Hill, New York.

Kawamura, K., Ng, L.L., Kaplan, I.R., 1985. Determination of

organic acids in atmosphere, motor exhausts and engine oils.Environmental Science and Technology 19, 1082}1086.

Kawamura, K., Kaplan, I.R., 1987. Motor exhaust emissions

as a primary source for dicarboxylic acids in Los Angeles

ambient air. Environmental Science and Technology 21,

105}110.

Lawrence, J.E., Koutrakis, P., 1994. Measurements of atmo-

spheric formic and acetic acids: methods evaluation and

results from "eld studies. Environmental Science and Tech-

nology 28, 957}964.

Liotta, F.J., Montalvo, D.M., 1993. The e!

ect of oxygenatedfuels on emissions from a modern heavy duty diesel engine.

SAE Technical Paper Series 932734.

Lipari, F., Swarin, S.J., 1982. Determination of formaldehyde

and other aldehydes in automobile exhaust with an

improved 2,4-Dinitrophenylhydrazine method. Journal of

Chromatography 247, 297}306.

Martin, B., Bigeard, P.H., 1992. Hydrotreatment of diesel fuels

} its impact on light duty diesel engine pollutants. SAE

Technical Paper Series 922268.

Montagne, X., Boulet, R., Guibet, J.C., 1991. Relation between

chemical composition and pollutant emissions from diesel

engines. Thirteen World Petroleum Congress, Buenos Aires

1991.

Possanzini, M., Di Palo, V., Petricca, M., Fratarcangeli, R.,Brocco, D., 1996. Measurements of lower carbonyls in

Rome ambient air. Atmospheric Environment 30 (22),

3757}3764.

Siegel, W.O., Richert, J.F.O., Jensen, T.E., Schuetzle, D., Swarin,

S.J., Loo, J.F., Prostak, A., Nagy, D., Schlenker, A.M., 1993.

Improved emissions speciation methodology for phase II of

the auto/oil air quality improved research program } hydro-

carbons and oxygenates. SAE Technical Paper Series No

930142.

Smith, L.R., 1985. Characterisation of exhaust emissions from

alcohol-fuelled vehicles. NTIS Report PB85-238582.

Souza, S., Vasconcellos, P.C., Carvalho, R.F., 1999. Low

molecular weight carboxylic acids in an urban atmosphere:

winter measurements in Sao Paolo City, Brazil. Atmospheric

Environment 33, 2563}2574.

Stone, R., 1992. Introduction to internal combustion engines.

SAE.

Ullman, T.L., 1989. Investigation of the e!ects of fuel composi-

tion on heavy-duty diesel engine emissions. SAE Technical

Paper Series 892072.

Zervas, E., Montagne, X., Lahaye, J., 1999a. In#uence of the

gasoline formulation on speci"c pollutants, Journal of Air

and Waste Management Association 1304}1314.

Zervas, E., Montagne, X., Lahaye, J., 1999b. Collection and

analysis of organic acids in exhaust gas. Comparison of

di!erent methods. Atmospheric Environment 33(29),

4953}4962.Zervas, E., Tazerout, M., 2000. Organic acids emissions from

natural gas feed engines. Atmospheric Environment 34 (23),

3921}3929.


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