A Feasibility Study on Retrofitting Diesel Oxidation Catalyst (DOC) to in-use old Diesel Vehicles in Hong Kong AWMA Conference June, 2003 Wing-tat HUNG,

A Feasibility Study on Retrofitting Diesel Oxidation Catalyst (DOC) to in-use old

Diesel Vehicles in Hong Kong

AWMA ConferenceAWMA Conference

June, 2003June, 2003

WWing-tat HUNG, Chun-shun CHEUNGing-tat HUNG, Chun-shun CHEUNG

The Hong Kong PolyUThe Hong Kong PolyU

WWai-Chuen MOK, Kong HA and Allan HUNGai-Chuen MOK, Kong HA and Allan HUNG

EEPD, Hong Kong SAR GovernmentPD, Hong Kong SAR Government

Hong KongHong Kong

• Population: about 7 millionPopulation: about 7 million

• Area: 1,099 square kmArea: 1,099 square km

• Road: 1,991 kmRoad: 1,991 km

• Licensed vehicles: 525,000Licensed vehicles: 525,000

• 275 vehicles per km275 vehicles per km

Vehicle Emission Problems Vehicle Emission Problems

• Taxis, goods vehicles, light buses and buses were diesel vehiclesTaxis, goods vehicles, light buses and buses were diesel vehicles

• 29 % of vehicle population - (17% Singapore, 10 % UK, 4 % 29 % of vehicle population - (17% Singapore, 10 % UK, 4 %

USA)USA)

• 98 % PM and 75 % NOx from diesel vehicles98 % PM and 75 % NOx from diesel vehicles

• 100 % of excessive smoky vehicles100 % of excessive smoky vehicles

• Cause record high Air Pollution IndexCause record high Air Pollution Index

Vehicle Vehicle Emission Control StrategyEmission Control Strategy

• Clean alternatives to diesel vehiclesClean alternatives to diesel vehicles

• Stringent new vehicle emission Stringent new vehicle emission

standards and fuel specificationstandards and fuel specification

• Strengthen in-use vehicle emission Strengthen in-use vehicle emission

inspectioninspection

• Strengthen enforcement against Strengthen enforcement against

smoky vehiclessmoky vehicles

Vehicle Vehicle Emission Control StrategyEmission Control Strategy

• Promote environmentally friendly driving and Promote environmentally friendly driving and

awareness of vehicle maintenanceawareness of vehicle maintenance

• Retrofitting in-use vehicles with emission Retrofitting in-use vehicles with emission

reduction devicereduction device

Retrofit DOC on BusesRetrofit DOC on Buses

• Started Diesel Oxidation Catalyst (DOC) trial in 1995Started Diesel Oxidation Catalyst (DOC) trial in 1995

• Fuel sulphur content: 2000 ppm to 500ppmFuel sulphur content: 2000 ppm to 500ppm

• Trial Result :Trial Result :

*FAS Test: Free Acceleration Smoke Test, similar to snap idle test*FAS Test: Free Acceleration Smoke Test, similar to snap idle test

Up to (HSU)Up to (%)Manufacturer A 0.2 41 65 Clogged

Manufacturer B 0.2 39 66 Passed0.2 18 51 Clogged

0.2 and 0.05 18 46 Normal0.05 9 22 Running

0.05 6 12 Running

Manufacturer Cwith muffler

State ofcatalyst

Sulphurcontent indiesel(%)

Smoke reduction (FAS Test*)Catalyst

Manufacturer C

•Custom design catalyst offers good Custom design catalyst offers good

resultresult

•Voluntarily installing DOC on Pre-Voluntarily installing DOC on Pre-

Euro and Euro I buses (2,600 units)Euro and Euro I buses (2,600 units)

•The trial of 400+ passive particulate The trial of 400+ passive particulate

traps ongoingtraps ongoing

Retrofit DOC on BusesRetrofit DOC on Buses

Implementation of Implementation of Retrofit TechnologiesRetrofit Technologies

Government actions:Government actions:

• Grants for Pre-Euro (pre-1995) diesel vehicle owners to install Grants for Pre-Euro (pre-1995) diesel vehicle owners to install

approved devicesapproved devices

• Light Diesel Vehicle (below 4 tonnes) Retrofitting ProgramLight Diesel Vehicle (below 4 tonnes) Retrofitting Program

• 2 approved devices with over 30% PM reduction and 3 years warranty 2 approved devices with over 30% PM reduction and 3 years warranty

• Low efficiency trapLow efficiency trap requires regular cleaningrequires regular cleaning

• CatalystCatalyst

• Completed on October 2001 (about 24,000 vehicles retrofitted)Completed on October 2001 (about 24,000 vehicles retrofitted)

Trial of Retrofitting DOC on Trial of Retrofitting DOC on HDDVHDDV

Heavy Duty Diesel Vehicles (over 4 Heavy Duty Diesel Vehicles (over 4 tonnes)tonnes)

• Started a trial in Dec 1999Started a trial in Dec 1999 • 59 trial vehicles were retrofitted 59 trial vehicles were retrofitted

with DOCs of different makeswith DOCs of different makes

Test FuelTest Fuel

• 500 ppm sulphur (Before Aug 500 ppm sulphur (Before Aug 2000)2000)

• 50 ppm sulphur (After Aug 2000)50 ppm sulphur (After Aug 2000)

Trial of Retrofitting DOC on Trial of Retrofitting DOC on HDDVHDDV

•23 Government vehicles (all comply with 23 Government vehicles (all comply with Euro-1 standardEuro-1 standard

•36 non-government vehicles (all except three 36 non-government vehicles (all except three are pre-Euro standard)are pre-Euro standard)

•Among non-government vehicles, 4 China Among non-government vehicles, 4 China trade vehicle, fueled with high sulphur diesel trade vehicle, fueled with high sulphur diesel from China Mainlandfrom China Mainland

•7 brands of DOC with 200 cpi to 300 cpi7 brands of DOC with 200 cpi to 300 cpi

Emission TestingEmission Testing

• FAS before and after the DOC (200 and 300 cpi) FAS before and after the DOC (200 and 300 cpi) installed;installed;

• Measure CO and HC before and after the DOC at high Measure CO and HC before and after the DOC at high idle, on road and at lug down test modeidle, on road and at lug down test mode

• Monitor exhaust gas temperature and backpressure Monitor exhaust gas temperature and backpressure before the DOC at high idlebefore the DOC at high idle

Trial of Retrofitting DOC on HDDVTrial of Retrofitting DOC on HDDV

Fittings for DOC in-use TestFittings for DOC in-use Test

Test Results (1)Test Results (1) Average 72% CO reduction

CO Reduction Efficiency, all vehicles, high idle

0

20

40

60

80

100

0 50 100 150 200 250 300 350

DOC Inlet Peak Temperature (deg C)

CO

Red

uct

ion

(%

)

Test Results (2)Test Results (2)Average 36% HC ReductionAverage 36% HC Reduction

HC Reduction Efficiency, high idle

0

20

40

60

80

100

0 50 100 150 200 250 300 350DO C Inlet Peak Temperature (deg C)

HC

Red

ucti

on (

%)

On-road CO test results On-road CO test results

Vehicle CO before DOC (ppm)

CO after DOC (ppm)

% reduction

V3 294 6 98

V34 (test 1) 197 4 98

V34 (test 2) 200 1 99

CO test results – CO test results –

Chassis Dyno Lug-downChassis Dyno Lug-down

VehicleVehicle CO (ppm) CO (ppm) before DOCbefore DOC

CO (ppm) CO (ppm) after DOCafter DOC

% % CO CO reductionreduction

V3V3 104104 33 9797

V4V4 150150 2020 8787

V20V20 150150 4040 7373

Test Results (3)Test Results (3)

Frequency Distribution of FAS Smoke Reduction for All Vehicles

0

5

10

15

20

25

30

35

40

45

50

-(50-60) -(40-50) -(30-40) -(20-30) -(10-20) -(0-10) 0-10 10-20 20-30 30-40 40-50

FAS Smoke Reduction (%)

Test Results (4)Test Results (4)

Peak Back Pressure

0

50

100

150

200

250

300

0 100 200 300 400 500 600 700Peak Temperature (deg C)

Pea

k P

ress

ure

(mba

r)

Test DOC

Maximum power for vehicle

V3 V4 V20

A Yes 49.1 kW at 2895 RPM 94 kW at 2779 RPM 141 kW at 2032 RPM

B No 48.4 kW at 2938 RPM 94 kW at 2768 RPM 141 kW at 2018 RPM

C Yes 52 kW at 2738 RPM 142 kW at 2053 RPM

D No 50 kW at 2752 RPM 143 kW at 2039 RPM

Test Results (4)Test Results (4)

Effects of DOC on Power Output under Lug-down Tests Effects of DOC on Power Output under Lug-down Tests

Associated Issues –White Associated Issues –White SmokeSmoke

White smoke observed after White smoke observed after extensive long idlingextensive long idling

• 5 concrete mixers5 concrete mixers• 3 lifting trucks3 lifting trucks

Under prolonged idling Under prolonged idling working conditionsworking conditions

Associated Issues - NOxAssociated Issues - NOx

Vehicle Sampling point

CO (ppm)

NO (ppm)

NO2

(ppm)

NOx (ppm)

V3 Before DOC 294 119 11.1 130

After DOC 6 113 9.1 119

V4 Before DOC 197 44 9.6 53

After DOC 4 44 10.7 54

V4 Before DOC 200 67 9.2 76

After DOC 1 58 7.2 65

On-road NOx measurementsOn-road NOx measurements

Associated Issues – Associated Issues – High Sulphur High Sulphur FuelFuel

Vehicle CO Conc. (ppm)

Smoke Opacity (HSU)

Efficiency of CO Reduction (%)

Efficiency of Smoke Reduction (%)

Before DOC

After DOC

Before DOC

After DOC

V26 361 85 20 20 77 -2

V26 235 28 54 45 88 17

V27 758 95 20 11 88 45

V27 338 273 34 23 19 32

V28 446 254 22 35 43 -58

V28 474 71 63 73 85 -15

V22 411 386 39 51 6 -29

V22 300 120 39 52 60 -33

V23 396 371 59 52 6 11

V23 204 180 69 61 12 12

Average 392 186.3 42 42 48•Sulphur content: 2700 – 3400 ppmSulphur content: 2700 – 3400 ppm

ConclusionsConclusions

DOC was found to be effective in reducing:DOC was found to be effective in reducing:•Smoke opacitySmoke opacity

•Average 72% COAverage 72% CO

•Average 36% HCAverage 36% HC

DOC was found to have minimal effects onDOC was found to have minimal effects on•Maximum Power Maximum Power

•NOxNOx

There may be problems of white smokeThere may be problems of white smoke

• Grants for Pre-Euro long diesel vehicle owners for Grants for Pre-Euro long diesel vehicle owners for installationinstallation

• Retrofitting Program started December 2002 (non cross-Retrofitting Program started December 2002 (non cross-boundary diesels) boundary diesels)

• Complete retrofitting of 30,000 vehicles in 18 monthsComplete retrofitting of 30,000 vehicles in 18 months • Tender for cross-boundary diesels in progressTender for cross-boundary diesels in progress

Installation Program Installation Program

for local Pre-Euro Diesel Vehiclesfor local Pre-Euro Diesel Vehicles

(0.005 % sulphur diesel)(0.005 % sulphur diesel)