Fuel Chemistry and Emissions Research

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Fuel Chemistry and Emissions Research

Fuel Chemistry and Emissions Research

W. Stuart Neill

Canadian Petroleum Products Institute March 3, 2010

Outline

• ICPET’s Oil Sands Program

• Clean combustion research

• Engine research facilities

• Experimental results

– Conventional diesel combustion of biodiesel blends

– HCCI combustion of oil sands and CRC FACE fuels

• Summary

• Future Work

• Final Remarks

Oil Sands Program

(Lead- Thom McCracken)

From resource production and processing … to end-use

Oil Sands Processing

Bitumen Production Upgrading

Blending & Pipelining

Clean Transportation Fuels Refining

Sustainability for Canadian Oil Sands

International

Competitiveness

(detailed emissions data available in Jacobs and TIAX

Goal Process change Fuels & technology for clean combustion

Research Areas

•

Oil sands chemistry and processing

– Luba Kotlyar, Patrick Mercier, Deepak Kirpalani

– John Woods, Floyd Toll, Judy Kung, Bussaraporn Patarachao, Indu Gedara

– Adam Donaldson & Adam Goodmurphy (U of O), Tetsuya Naito & Koichi Haneda (Nagoya U) – Shahrzad Hashimi (RA)

– Om Patange and Aakash Ravi (students) – Bryan D. Sparks (Project Consultant)

•

Fuel chemistry for clean combustion

– Stuart Neill, Hongsheng Guo

– Vahid Hosseini, Cosmin Dumitrescu (RA)

– Wally Chippior, Roland Vaivads, Simon Lafrance – Ronak Choudhary (student)

•

Carbon Capture & Sequestration (CCS) chemistry

Fundamental understanding for improvement to commercial operations

Oil Sands Processing

Upper Rag Layer

Clear Water

Lower Rag Layer Samples from pilot and

commercial operations

Lab sample preparation

1000 1400 1800 2200 2600 3000 Temperature (K) 0 1 2 3 4 5 6 Equivalence Ratio (φ )

soot

NOx

Source: Akihama et al., SAE 2001-01-0655

LTC

Compression Ignition

•High efficiency

•Produces soot & NO_x •Requires aftertreatment PFI Spark-Ignition •Low efficiency •Produces NO_x, HC & CO •Requires 3-way catalytic converter Homogeneous Charge CI •High efficiency

•Ultra-low soot & NO_x •High HC & CO

•Combustion phasing control?

Research Facilities

Clean Diesel Combustion

Caterpillar SCOTE engine with Ganser CRS fuel injector

Premixed Combustion

Cooperative Fuel Research (CFR) engine with air-assist port fuel injector/vaporizer

Common rail fuel injector

Diesel Combustion

1 Single-cylinder diesel engine

2 Exhaust surge tank

3 Exhaust back-pressure valve

4 Diluter, heater

5 Filter enclosure

6 Rupture disk

7 EGR cooler

8 EGR valve

9 Intake surge tank

10 Intake heater

11 Air mass flow meter

12 Fuel mass flow meter

13 Dynamometer

(

)

E

WF

BSE

P

WF

⎛

_×

⎞

⎜

⎟

⎝

⎠

=

×

∑

∑

Test Procedure

Biodiesel Properties

PM Emissions

• All four B20 blends had significantly lower PM

emissions than the ULSD base fuel, a commercial diesel fuel with 15 ppm S

• PM measurement repeatability

issues were encountered during these experiments Biodiesel Blend (%) 0 5 10 15 20 P M Emi ssi ons (g/ hp-hr) 0.03 0.04 0.05 0.06 0.07 Canola Soy Tallow Mustard

NO

Emissions

• NO_x emissions for all B20

blends were higher than those of the ULSD fuel

• NO_x emission measurement

repeatability with the reference fuel was very good

• Biodiesels with the lowest PM emissions had the highest NO_x emissions

Fuel Consumption

• The B20 biodiesel blends had

~2.3% higher BSFC on a mass basis due to the lower heats of combustion of the biodiesel blending components

• However, fuel consumption was

approximately equivalent on an energy basis

Heat Release

(mode 7)

Summary

Biodiesel Blends

• Biodiesel blends (

≤ B20) derived from four feedstocks showed

satisfactory performance, emissions and combustion

characteristics in a MY 2004 heavy-duty diesel engine

– BSFC was similar on an energy basis

– PM emissions were reduced by 20% on average with B20

– NO

emissions were increased by 9% on average with B20

• The main issues regarding the use of biodiesel blends in current

diesel engine technology are:

– Biodiesel quality (ASTM D6751), especially oxidative stability

– Cold climate issues (cloud point, blend concentration, blending

procedures)

Emission Standards

Heavy-Duty Diesels, MY 2010

• Engine designers have two

options to meet the new

diesel emission standards

o Reduce in-cylinder pollutant formation using advanced combustion strategies

o Emissions control systems

PM - NO_x Emission Trade-off (Modes 5-8)

2010 Emission Standards 0.01 g/hp-hr PM limit 0.20 g/hp-hr NO_x limit NOx Emissions (g/hp-hr) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 PM Emissions (g/hp-hr) 0.00 0.05 0.10 0.15 0.20 0.25 ULSD B5 Canola B10 Canola B20 Tallow B20 Soy B20 Canola B20 Mustard

Experimental Setup

Experimental Setup

• Fuel vaporizer allows us to preheat and partially vaporize middle distillate fuels upstream of the intake port

• Ability to vary T_vap from 140 to 300°C while

maintaining fuel-air

mixture constant (75°C) at the intake port

HCCI Combustion

Oil Sands Diesel Fuels

• A minimally processed and low cetane number (36.6) fuel

derived from oil sands (OS-CN36) was used as the base fuel in

the study

• Three different methods were applied to modify the base fuel to

achieve higher CN fuels:

• Hydroprocessing

• Addition of cetane improver

• Blending with a Supercetane™ renewable diesel fuel

• The base fuel (OS-CN36) was hydroprocessed in two stages.

Cetane numbers were 39.4 (OS-CN39) and 41.4 (OS-CN41),

respectively

Procedure

Controlled Input Conditions

• The air-fuel ratio (AFR) and exhaust gas recirculation (EGR) were

varied and the resultant engine combustion behavior (power, efficiency, emissions) was measured

• Other initial conditions were fixed for this experiment:

Fuel vaporizer temperature (T_vap, °C) 220

Intake mixture temperature (T_mix, °C) 75

Compression ratio 13:1

Engine speed (rpm) 900

Results

AFR-EGR Operating Region

• Increasing the oil sands

hydroprocessing severity shifted the operating region for HCCI combustion towards leaner mixtures

The base fuel (OS-CN36) OS-CN39 OS-CN41

Summary

Oil Sands Diesel Fuels

• Increasing the fuel cetane number shifted the AFR-EGR operating window for HCCI combustion towards higher AFR (leaner mixtures) and reduced the cyclic variations

• Higher EGR rates were required to operate the higher cetane number fuels at lower AFR (richer mixtures). This led to a significant decrease in the maximum engine power produced for the higher cetane number fuels with a fixed boost pressure

• The hydroprocessed fuels had more stable and complete HCCI combustion than the base fuel, which resulted in reduced CO, HC, and NO_x emissions and lower ISFC

• The addition of a nitrate cetane improver increased ISFC and led to substantially higher NO_x emissions on a relative basis, but the absolute emissions were still very low. Blending a renewable diesel component increased the ISFC and HC emissions

HCCI Combustion

CRC FACE Fuels

• Develop a fundamental understanding of fuel chemistry effects on the compression ignition behavior of homogeneous mixtures of diesel fuel, air and recycled exhaust products

FACE Cetane Number

Aromatic Content

T90

1 Low Low Low

2 Low Low High

3 Low High Low

4 Low High High

5 High Low Low

6 High Low High

7 High High Low

8 High High High

T

Sweep

Input Parameter Value

Speed 900 rpm λ 3.5 CR 12.25:1 MAP 110 kPa EGR 0 % T_mix 75 °C T_air variable T_vap variable

Soot Emissions

• HCCI combustion produces

soot if fuel-air mixture

preparation is not completed prior to autoignition

• The nine FACE fuels had

different vaporizer temperature requirements to achieve 0 FSN

• The two high CN, high T90

fuels (6 & 8) had the highest soot emissions

• The two low CN, low T90 fuels

(1 & 3) had the lowest soot emissions

isNO

_x

Emissions

• isNO_x emissions were

<0.015g/kW-hr for all FACE fuels when the vaporizer temperature was 270°C or higher

• isNO_x emissions decreased

simultaneously with soot

emissions as the fuel vaporizer temperature increased (i.e.

there was no soot-NO_x emission trade-off)

CR Sweep

Input Parameter Value

Speed 900 rpm λ 1.2 CR variable MAP 110 kPa EGR 60% T_mix 75°C T_air variable T_vap 270°C

Combustion Phasing

• HCCI combustion phasing

(CA50) is a strong function of engine CR

• The four low CN fuels exhibited significantly delayed CA50

phasing compared to the

Mean Effective Pressure

• The four low CN fuels (Face No.

1-4), as well as the two high CN, low T90 fuels (Face No. 5 & 7) were able to achieve the highest peak IMEPs at fixed

MAP, λ and EGR

• The operating range, in terms of CR, was wider for the high CN fuels

• The high CN, high aromatic,

high T90 fuel (FACE No. 8) had the lowest achievable peak

Fuel Consumption

• The minimum ISFC for the four

low CN fuels occurred when CA50 was ~5°ATDC

• The minimum ISFCs for the

lower CN fuels were better than those for the high CN fuels, but ISFCs of the low CN fuels

seemed to be more sensitive to CA50 phasing

• The two low CN, low aromatic

fuels (FACE No. 1 & 2) had the lowest minimum ISFCs

• The two high CN, high T90

fuels (FACE No. 6 & 8) had the highest minimum ISFCs

Typical HCCI Results

Parameter Measured Level 2010 Standard

ISFC ~240 g/kW-hr

Soot <0.1 FSN 0.013 g/kW-hr (PM)

isNO_x ~0.005 g/kW-hr 0.27 g/kW-hr

isHC ~5 g/kW-hr 0.19 g/kW-hr

Summary

HCCI Combustion

The preliminary findings from our HCCI combustion experiments

with the oil sands derived and FACE fuels are as follows:

• For pure HCCI combustion, improving the homogeneity of the fuel-air

mixture (by increasing the vaporizer temperature) simultaneously

reduced soot, NO_x, HC and CO emissions

• Soot emissions (AVL FSN) increased with increasing CN and T90

• The four low CN fuels (Face No. 1-4), as well as the two high CN, low T90 fuels (Face No. 5 & 7) achieved the highest peak IMEPs at fixed

MAP, λ and EGR

• The two low CN, low aromatic fuels (FACE No. 1 & 2) had the lowest minimum ISFCs

Future Work

• Compare clean diesel combustion (CDC) of oil sands derived and

FACE fuels in Caterpillar engine with the HCCI combustion results

• Compare CDC & HCCI combustion of oil sands and CRC FACE fuels

• Compare direct hydrogen gas enrichment of HCCI combustion to

hydroprocessing of liquid fuels

PCCI1 _HCCI2 SFC, g/kW-hr 239 240 NOx, g/kW-hr <0.04 0.005 HC, g/kW-hr 1.2 ~5 CO, g/kW-hr 9.0 ~10 1 _brake, 2 _indicated

Final Remarks

• Advanced diesel combustion strategies offer the potential for

high fuel conversion efficiency without the problematic PM and

NO

emissions associated with conventional diesel combustion

• However, engine designers must deal with low temperature

oxidation of HC and CO exhaust emissions using aftertreatment

• In clean diesel combustion, objective is to achieve rapid fuel-air

mixing using very high fuel injection pressures in conjunction

with high levels of charge dilution to slow down the reaction

kinetics

• HCCI combustion results suggest that high volatility (low T90)

and a relatively low cetane number are desirable fuel properties

Acknowledgements

• The

authors

gratefully

acknowledge

the

following

contributions:

o The financial support provided by the Government of Canada’s

PERD/AFTER and ecoETI programs

o The technical expertise (fuel analyses, pilot plant) provided by the National Centre for Upgrading Technology (NCUT)

o The financial support, technical expertise, fuels, and fuel analyses provided by the Canadian Petroleum Products Institute (CPPI)