A17_Unregulated Engine Emissions and Control Using DOC

7/28/2019 A17_Unregulated Engine Emissions and Control Using DOC

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Unregulated Engine Emissions and TheirUnregulated Engine Emissions and Their

Control Usin DOC, PFF and CRTControl Usin DOC, PFF and CRT


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IntroductionIntroduction

The increasing use of diesel engines due to their fuel economy,durability and power advantages has contributed to the sum total ofexhaust emissions.

Need of clearly understanding these emissions. Emission can be classified into two broad categories-

egu ate em ss ons

Unregulated emissions

Most of the emission regulations in the world are mainly concernedabout regulated emissions.

Need to reduce the unregulated emissions.

Unre ulated emissions are more challen in to com are amoninvestigators for several reasons.

Vast number of unique compounds that exist in combustionexhaust roducts.

Requires expensive analysis techniques [Mullen et al1].


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Major Unregulated Emission CompoundsMajor Unregulated Emission Compounds

Major unregulated emissions:

PAHs

Carbonyl compounds BTEX etc.

s nown or t e r carc nogen c propert es.

No strict regulations for PAHs emission. PAHs toxicity is very

structurally dependent.

A carbonyl group is a functional group composed of a carbon atomdouble-bonded to an oxygen atom.

, ,ethylbenzene, and xylenes.

Have harmful effects on the central nervous system.


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Major Unregulated Emission CompoundsMajor Unregulated Emission Compounds

Fig 2 Carbonyl Group, Aldehyde and

Fig 1 Priority listed PAHs. *Not included in priority list,,

human carcinogen). [Ravindra et al7]


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Measurement Techniques for Unregulated Emission from CIMeasurement Techniques for Unregulated Emission from CI

EnginesEngines Karavalakis et al, have performed experiments for determining the regulated and

unregulated emissions

.

For determining the carbonyl compounds, they have collected the samples in a 3LTedlar bags.

.

Cartridges contains 2, 4-dinitrophenylhydazine on silica substrate.

By using ultra-violet visible detector, carbonyl-DNPH derivatives were analyzed.

co umn was use or t e separat on o car ony compoun s.

For determining the PAH and nitro-PAH, samples were collected on glass fiber

filter.

na y a gas c romatograp g ent w t a mass spectrometr c

detector (Agilent 5975B) was used for the PAH and nitro-PAH analysis.

Tan et al, have used five different diesel fuel with different sulfur content

or t e measurement, t ey ave use an mu t -component gas ana yzer.

capable of measuring over 25 gaseous components including the measurement ofunregulated emissions (HCHO, MECHO and SO2) also. Paper #


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Measurement Techniques for Unregulated EmissionMeasurement Techniques for Unregulated Emission

Karavalakis et al8, have performed experiments for determining theregulated and unregulated emissions by a passenger vehicle usingdiesel/biodiesel blends under ADC (Athens driving cycle) andNEDC (New european driving cycle). ute w t a r n ut on tunne . For determining the carbonyl compounds, C18 column was used.

For determining the PAH and nitro-PAH- glass fiber filter, Gas

were used.

For the measurement, AVL PEUS multi-component gas analyzer

. Capable of measuring over 25 gaseous components including the

measurement of unregulated emissions (HCHO, MECHO and

2 .


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Measurement Techniques for Unregulated EmissionMeasurement Techniques for Unregulated Emission

Cheung et al10 have performed experiments on a four cylinder direct

injection diesel engine for regulated and unregulated emission withULSD and its blends with ethanol as fuels.

, ,formaldehyde, ethanol etc) by using the Air-sense multi-

component gas analyzer. t ano was ca rate y an n rect way.

Kept the engine running for some time till the exhaust gas

temperature, cooling water temperature, lubricating oil

temperature and CO2 gas concentration in the exhaust stabilizes.


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Effect of Engine Operating Condition and FuelEffect of Engine Operating Condition and Fuel

Com osition on Unre ulated EmissionCom osition on Unre ulated Emission

Effect of diesel/biodiesel blends under ADC and NEDC. [Karavalakis8

Main focus was to investigate the impact of regulated andunregulated emissions with the use of diesel/biodiesel blends

.

Carbonyl compounds (CBCs), Polyaromatic hydrocarbons

(PAHs) and Nitro-PAHs have been measured. our erent ue s, ese an t ree en s w t , ,

biodiesel from soybean oil were used for the experiment.

Formaldehyde was the major compound in both the cases which

was o owe y aceta e y e. Determined 11 PAHs and 5 nitro-PAHs.

Major PAHs emission were of low molecular weight which arefollowed by higher molecular weight PAHs.


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Table 1: Emissions of carbonyls (mg km-1) from diesel fuel and biodiesel blends when thevehicle operated over NEDC and ADC. [Karavalakis et al8]

Carbonyls(mg km-1) NEDC ADC

Diesel B5 B10 B20 Diesel B5 B10 B20Formaldehyde 6.84 5.46 4.61 3.64 11.1 7.74 6.55 4.35

Acetaldehyde 2.86 2.24 1.9 0.49 3.82 4.05 2.1 1.58

Acrolein/acetone 0.73 0.75 2.31 2.2

Propionaldehyde 2 1.56 0.96 1.02 2.89 0.67 0.71

Crotonaldehyde 1.72 1.75 1.89 1.42 3.49 3.37 3.99

Methacrolein 3.51 14.3 2.24 3.3

2-Butanone 0.82 0.85 1.38 2.04

Butyraldehyde 3.81 4.3 2.46 1.52 7.75 7.87 6.23 5.47

Benzaldehyde 3.58 3.76 4.17 3.62 3.98 6.75

Valeraldehyde 5.94 5.47 2.56 12.8 9 11.1 1.29

p-Tolualdehyde 1.34 1.87 3.15 2.28 2.82 6.88 Hexanaldehyde 0.63 0.47 0.56 7.86 5.66 6.35

.

Lower saturated aromatic hydrocarbons in biodiesel blendsresponsible for lower HCHO emission for higher blends.


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Composition on Unregulated EmissionComposition on Unregulated Emission

Effect of different sulfur content. [Tan et al9]

Performed ex eriment on a li ht dut diesel en ine with different

sulfur content fuels (S50, S350, S500, S800 and S1500). The investigations have been done on three unregulated

emission formaldeh de acetaldeh de MECHO as mentionedand SO2.

Formaldehyde emission was non-detectable. , , ,S800 and S1500 at two different speeds at 1900 rpm formaximum torque and 4000 rpm at maximum power withincreasin load in each case 0% 25% 50% 75% and 100%

loads).


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Fig 5: MECHO emission (n=1900 rpm) Fig 6: MECHO emission (n=4000 rpm)

Acetaldehyde emission decreases with increasing load and decreaseswith fuel sulfur content.

decreases with decreasing sulfur content in fuel.


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Fig 7: SO2 emission (n=1900 rpm) Fig 8: SO2 emission (n=4000 rpm)

SO2 emission increases with increasing sulfur content

As the fuel injection quantity increases, the emission of SO2 willncrease.


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Fig 9: SO2 reduction and fuel sulfur content (n=4000 rpm), [Tan et al9]

Calculated the average reduction extent of SO2 emission for five fuelswith different sulfur content keeping S1500 as base fuel.

Engine SO2 emission is directly related to the sulfur quality in the fuel.


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Composition on Unregulated EmissionComposition on Unregulated Emission

Fig 11: Effect of ethanol and engine load onformaldehyde emission

Fig 12: Effect of ethanol and engine load onacetaldehyde emission

Formaldehyde emission increases with the increase in engine loadand it decreases with the increase in alcohol content in ULSD. Thepossible reason is increased H/C ratio.

Decrease in acetaldehyde emission at high load because of high

combustion temperature.


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Table 3: Ethene, ethyne and 1,3-butadiene emissions at various engine loads.

1800(rev

min1)

0.20

MPa 0.38

MPa .55

MPa

C2H4 C2H2 C4H6 C2H4 C2H2 C4H6 C2H4 C2H2 C4H6

(ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm)ULSD 35.8 106 46.2 35 97.2 45.2 22.4 54.3 31.1

Blend1 44.7 109 49 30.1 82.8 44.4 19.2 45.7 24.3Blend2 23.7 49.6 29.5 22 43.5 28.1 14.4 26.4 21Blend3 33.6 62.5 41.1 28.1 47.5 35.8 16.8 28.1 21.8

Ethene and ethyne are the products of pyrolysis between diesel andethanol.

. . . . . . . .

C2H2 and C2H4 emission decreases with the increase of engine load.


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Effect of Engine Operating Condition and Fuel Composition onEffect of Engine Operating Condition and Fuel Composition on

Unre ulated EmissionUnre ulated Emission

Table 4: Benzene, toluene and xylene emissions atvarious engine loads.

mg KWh-1 0.20 MPa 0.38 MPa .55 MPa

C6H6 C7H8 C8H10 C6H6 C7H8 C8H10 C6H6 C7H8 C8H10

ULSD 79.2 17.1 69.7 57 8.3 33.2 28.1 3.3 18.7

Blend-1 95.9 8.7 58.3 54 4.3 28.9 23.6 2.6 17

Blend-2 97.2 9.1 38 53 4.3 18.2 20.8 2.5 10.6

Blend-3 112.6 9.4 55.3 48.9 4.1 24.5 26 1.9 12.5

Benzene oxidizes easily at high combustion temperature (high load).

Blend-4 153 13.8 66.8 63.4 5.8 25.3 30.3 3.2 13.4

Toluene and xylene also have the same trend as benzene.

At low engine load (low exhaust temperature) with high blend may.


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ConclusionsConclusions

It has been observed that addition of biodiesel with diesel reduced thecontent of aldehyde emission in the exhaust and the emission in hot startcondition NEDC test cycle is less than the cold start ADC test cycle.

Formaldehyde was by far most abundant carbonyl in the exhaust. Theconcentration of MECHO emission of the engine decrease with the fuelsulfur content.

The SO2 concentration increases with the engine load. SO2 emissiondecreases linearly with descending fuel sulfur content.

,emission reduces with increasing engine load. There is a sharp decrease inthe unburned ethanol emission with decreasing sulfur content.

,

load and decreases with the addition of ethanol in diesel with ultra lowsulfur content.

, . ,low combustion temperature leads higher BTX emission.


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Diesel Oxidation Catalysts (DOC)Diesel Oxidation Catalysts (DOC)

Oxidizes CO and HC to CO2 and H2O

desired

Oxidizes toxics such as aldehydes

xi izes 2 to 3 un esire

Oxidizes Soluble organic fraction (SOF,

Ceramic Catalyst

s a sor e on ar cu a es o re ucePM

PM reduction up to 50% depending on SOFcontent of PM; Typically 25% on new engines

DOC in a muffler


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Particulate Matter OxidationParticulate Matter Oxidation


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Catalyst

Carbon

SootCarbon

Soot

Note: Soluble Organic Fraction,

Vapor form.


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Diesel Catalytic Converter(Diesel Oxidation Catalyst)


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Oxidizes SOF fraction of PM Lower cell density and low back

constrains

Thermal & Chemical stabili ty ofcatalyst is a challenge May be useful under Indian

scenario, if fuel quality isimproved

Limitations

Lower particulate controlefficiency

Formation of sulfuric acid, sulfate


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Noble Metals vs NonNoble Metals vs Non--Noble MetalsNoble Metals

Pt, Pd, Rh cost !!Pt, Pd, Rh cost !!

,,

- Multicom onent s stems

Catalysis / Adsorption: Environmental Applications


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- Poor control on catalytic processes- Complex interface

-

- Chemical & thermal stability

- Cost, techno-economic feasibility

- Disposal , LCA (catalyst or adsorbent volume?)

- Phase transfer not feasible

Non-Noble Metal Based Catalysts

Very wide range of catalysts: metals; metal complexes; oxides;composites mixed oxides; perovskites; etc

Many industrial applications- From Fe based catalyst for Habersprocess to Ti-silicalite, Ceria to SnO2


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Mixed Oxides and Perovskites

Advantages:


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- Low cost: - Sometimes cost is not a ig issue- Disposable type catalysts ? VOCs Environmental issues ??

- Tailoring possibilities

- New designs (still coming up !!)-- Combinatorial approaches

- Thermal stabilit or combustion reactions etc

Limitations: - Surface area, microporosity (per unit SA activity !!)

- Low temperature activity

-


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on nuousy egenera ng rap

CRTCRT Particulate FilterParticulate Filter Operating PrincipleOperating Principle


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Use of NOx Within CCRT SystemUse of NOx Within CCRT System


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CRT Filter SystemCRT Filter System


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CContinuouslyontinuously RRegeneratingegenerating TTraprap Principle

Oxidation of NO to NO2 inside Pt catalyst

Conversion of stored soot in trap by NO2

Continuously Regenerating Trap (CRT)


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Utilize the strong oxidizing property of NO2Unit consists of P based catal st u stream of Filter to oxidize NOto NO2

NO2 oxidizes the soot(C) into CO2 in the trap

+ ---> +CO(g) + NO2(g) ---> CO2(g) + NO(g) (2)

2 NO(g) + O2(g) ---> 2 NO2(g) (3)

This system is very sensitive tosulphurcontent of fuel (S


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urner regenerat on system


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Electrical Regeneration


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A device that vastl reduces emission of

particulate matter (the main particle

com onent of black smoke from dieselengines of buses

Mitsubishi DPF System


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S stem

Mitsubishi put this system for practical use first time in Japan in busessucceeded in removing 80 % of PM even removes 100 % of black smoke

Overview of the Mitsubishi DPFOverview of the Mitsubishi DPF

ystemystem


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ystemystem The Mitsubishi DPF System traps particulate matter

in a porous ceramic i ter, an t is accumu ateparticulate matter is periodically burned. By

re ularl exchan in two filters to continuousl traand burn particulate matter, it can be continuouslycollected while the bus is running.


ystemystem


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ystemystem

System Overview Two filter assembl

Exhaust gas control valve

Air flow sensor, temperature

& pressure sensors

Electric heater & convectorThe Mitsubishi DPF System.


ystemystem


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ystemystem

Particulate matter collection

The fil ters use a heat-resistant, finely porous ceramic material. These pores,

Using 2 filters, exhaust gas is passed through one filter until the

accumulation level reaches a specified point, at which the exhaust gas flow

matter col lection by the other fil ter


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Approximately 80% of particulate matter is eliminated,

achieving output levels of only half those specified in theong- erm ex aus gas res r c on arge .

Moreover, black smoke, which accounts for most (65%)

of articulate matter, is 100% eliminated, makin exhaust

invisible to the eye.


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Effectiveness of particulate

matter reduction.

Effectiveness of black smoke

reduction.


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art a ow tersart a ow ters


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A17_Unregulated Engine Emissions and Control Using DOC

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