Exhaust Emission Reduction Technologies of Diesel HDV in JAPAN China RT 2009 Emissions & Fuel Efficiency Subcommittee Japan Automobile Manufacturers Association Toshiaki KAKEGAWA 1
CONTENTS 1. History of Diesel Emission i Reduction Measures 2. Technologies for Compliance to New Long-Term Regulations 3. Technologies for Compliance to Post-New Long-Term Regulations 2
1. History of Diesel Emission i Reduction Measures 3
Characteristics of Diesel Emissions Gasoline engines Diesel engines Exhaus st gas constitu uents CO HC NOx PM CO2 Substantially reduced by threeway catalysts & EGR (exhaust gas recirculation) Below problem levels Disadvantage: Larger fuel consumption due to low combustion efficiency Extremely low emissions Extremely low emissions Disadvantaged by high combustion temperature Trade-off relation with NOx: Due to air shortage during diffusive combustion Advantage: Smaller fuel consumption due to high combustion efficiency 4
NOx Reduction Methods for Diesel Vehicles (Specific Methods) Injection timing delay NOx Reduction Combustion temperature suppression Fuel properties improvement po e Exhaust after-treatment Swirl reduction Pilot injection EGR Stepped-up cooling of turbo air Emulsion fuel Water injection Sulfur content reduction Aromatics content reduction NOx selective-reduction catalyst NOx storage-reduction catalyst 5
Structure and Composition of Diesel Particulate SOF (Soluble Organic Fractions) : Remnants of half-burned fuel & lubricant Soot: Product of incomplete combustion of fuel & lubricant Sulfate: Generated by oxidation of fuel sulfur contents during combustion 6
PM Reduction Methods for Diesel Vehicles Smoke Reduction (promoted diffusive combustion) SOF Reduction (reduced HC) Sulfate Reduction Use of air jet in combustion latter-phase Spray fractionization Increase of air ratio Improve air utilization Lubricant consumption cut Improve fuel properties Exhaust after-treatment (Specific Methods) Turbulent combustion Reentrant-reinforcing combustion chamber High-pressure injection (>1,000 atm) Nozzle hole miniaturization Inertia supercharging Intercooler-eguipped supercharger Nozzle hole multiplication Combustion chamber cubage trimming Lubricant properties improvement Piston parts improvement Cetane index increase Sulfur content reduction Aromatics content reduction Oxidation catalyst DPF 7
( ) History of Diesel Exhaust Emission Control Emission reducing technologies Ex xhaust emissio n meas ures Engine m ainframe Fuel injection n system In take & exhau st systems Other t Afterreatment Emission regulations Year '74 '77 '79 '83 '89 '94 '97 Regulation Combustion chamber improvements (e.g., idle- cubage trimming) Displacement & compression ratio increase; improved cooling of combustion chamber EGR LOC reduction Injection timing delay; modified characteristics of governor and timer Injection nozzle and tube modification Higher-pressure injection pump Variable pre-strokes Electronic control of governor and timer Two-stage spring nozzle Variable injection rate control (VE pump) Intake & exhaust ports improvement Supercharging & supercharger improvement Intercooling & variable inertia supercharging Variable nozzle turbo Variable swirl mechanism (sub-port type) Minimized dispersions in emission-related parts & tuning accuracy Start assist device improvement Oxidation catalyst DPF NOx reducing catalyst (NOx storage-reduction catalyst, urea SCR) 74Reg 77Reg 79Reg 83Reg 89Reg Short- Term Reg Long- Term Reg 02 New Short- Term Reg 8 CR
2. Technologies for Compliance to New Long-Term Regulations 9
History of HDV Emission Limit Values 0.3 PM (g/kwh) 0.25 0.2 Long-Term Regulations (1997 onward) 0.15 New Short-Term Regulations (2003 onward) 0.1 005 0.05 0 PM PM 0 1 2 3 4 5 6 NOx(g/kW/h) New Long-Term Regulations (2005 onward) Post-New Long- Term Regulations (2009 onward) New Short-Term Regulations' super-low PM vehicle certification standards 10
Emission Limits of Japan, U.S. and Europe (JP2005 denoting Japan's New Long-Term Reg.) 11
Comparison of HDV Emission Limit Values (Gasoline/LPG, Diesel, CNG) NOx (g/kwh) 4 Diesel New Short-Term Gasoline/LPG New Long-Term CNG New Short-Term 3 2 1 Diesel New Long-Term Gasoline New Short-Term 20 16 12 8 4 CO (g/kwh) 0 0 0.2 0.4 0.6 0.8 1 0. 1 HC or NMHC (g/kwh) 0. 2 0. 3 PM (g/kwh) 12
New Long-Term Compliance Technologies - (1) Urea selective catalytic reduction(scr) + High-pressure fuel injector + Cooled EGR PM is reduced by the high-pressure fuel injector which improves combustion. NOx is reduced by the cooled EGR (improving combustion) and by the urea SCR. SCR is a catalytic system that reduces NOx into harmless nitrogen, using ammonia generated from urea solution as reducing agent. EGR valve Intercooler (charging air cooler) High-pressure unit injector High-pressure common-rail NOx reducing urea SCR EGR cooler Intake air Oxidation catalyst Oxidation catalyst Exhaust Feeding module Urea solution tank Air tank Urea solution injector 13
New Long-Term Compliance Technologies - (2) DPF + High-pressure fuel injector + Cooled EGR PM is reduced by the high-pressure fuel injector (improving combustion) and by the DPF. NOx is reduced by the high-pressure fuel injector and the cooled EGR, both improving combustion. The DPF is a ceramic filter for trapping PM from exhaust emissions. EGR valve High-pressure common-rail Intake throttle ttl Intercooler (charging air cooler) EGR cooler Intake air Oxidation catalyst DPF (ceramic filter) Exhaust VG turbo 14
Injection Pattern of a High-pressure Common-rail Fuel Injector for a New Long-Term Regulation Complying Engine with DPF Main injection Pilot injection Afterinjection Postinjection Common-rail (fuel route common to all cylinders) Fuel pressurizing pump Top dead center of piston 15
Structure of the EGR Cooler Outlet 出口 チューブ Tube A EGR gas ガス inlet 入口 ガス Gas outlet 出口 A-A A Cooling 冷却水入口 water inlet シェル Shell 16
Continuous Control of the VG Turbo and EGR Actuator ECU-integrated construction DC motor Non-contacting position sensor Actuator DC motor Non-contacting position sensor EGR Gas In Controller for CAN Butterfly Valve EGR Gas Out 17
A Precision Fuel Injection Control System ECU : IN OUT(CAN Line) ECU : IN ECU : OUT ECU Intercooler Air Flow Sensor VG Turbocharger with DC Motor Pressure Sensor Temp. Sensor Pressure Sensor Exhaust Brake DPR Cleaner Engine Speed & Crank kangle Sensor Pulse EGR System Common-Rail Injection System Pressure Sensor Boost Pressure Sensor EGR Valve with DC Motor High-Performance EGR Cooler 18
Technologies and Fuel Economy by Vehicle/Engine Type - (1) GVW 3.5t or less Light trucks Medium trucks Displacement Combustion technology After-treatment technology No. of types Total complying to Injection sys. VG Cool Continuous control Hybrid fuel No. of (L) DPF Urea NSR economy types CR Other turbo EGR VG EGR SCR standard 200 2.00 O - - O - O O - - - - 16 2.98 O - O O O O O - - - - 12 2.95 O - - O - O O - - - 0 28 2.98 O - - O - O O - - - 0 17 2.98 O - - O - O O - - O 4 4 3.00 O - O O O O O - - - 112 242 3.00 O - O O O O O - - O 14 14 4.01 O - O O O O O - - - 26 280 4.01 O - O O O O O - - O 25 26 4.01 O - O O O O O - O - 0 2 473 4.73 O - O O O O O - - - 0 43 4.90 O - - O - O O - - - 0 137 5.19 O - O O O O O - - - 11 19 6.40 O - O O O O O - - - 153 587 7.55 O - - O - O O - - - 0 32 7.68 O - O O O O O - - - 0 183 7.79 O - O O O O O - - - 4 16 19
Technologies and Fuel Economy by Vehicle/Engine Type - (2) Heavy trucks Light buses Medium buses Heavy buses Displacement Combustion technology After-treatment technology No. of types complying to Injection sys. VG Cool Continuous control Hybrid fuel (L) DPF Urea NSR economy CR Other turbo EGR VG EGR SCR standard 9.20 O - O O O O - O - - 0 14 9.84 O - O O - O O - - - 36 158 12.74 - O O O - - O - - - 12 12 Total No. of types 12.88 O - O O - O - O - - 10 164 12.91 O - O O O O O - - - 44 255 13.07 - O O O O O - O - - 48 172 15.68 O - O O - O O - - - 35 74 4.01 O - O O O O O - - - 0 14 4.73 O - O O O O O - - - 0 8 4.90 O - - O - O O - - - 0 19 640 6.40 O - O O O O O - - - 0 9 7.68 O - O O O O O - - - 0 4 7.68 O - O O O O O - - O 2 2 7.79 O - O O O O O - - - 37 108 490 4.90 O - - O - O O - - O 2 2 9.20 O - O O O O - O - - 21 31 7.55 O - - O - O O - - - 4 11 12.88 O - O O - O - O - - 4 4 12.91 O - O O O O O - - - 6 6 20
The New Long-Term Regulation Compliant Hino AO9C Engine New heavy truck engine with L6 OHC structure 9L displacement (replacing conventional 11-13L 13L engines) No. of fuel economy standard compliant types / Total No. of types: 27 / 66 Electronic-controlled Electronic-controlled continuous EGR continuous variable valve nozzle turbo High-pressure multiple injection common-rail system Large-capacity EGR cooler Catalyst-reinforced DPF 21
The New Long-Term Regulation Compliant Mitsubishi-Fuso 6M70 Engine New heavy truck/bus engine with L6 OHC structure 12.9L displacement (with urea SCR system) No. of fuel economy standard d compliant types / Total No. of types: 14 / 168 Precision cooled EGR system Variable nozzle turbo Common-rail fuel injection system After-stage oxidation catalyst SCR catalyst Urea feeding Pre-stage oxidation catalyst 22
New Technologies and Compliance to New Long-Term Regulations Adopted Technologies and Fuel Economy Compliance: Summary (1) A total of 25 diesel engine models for vehicles exceeding a GVW 3.5t have been certified as compliant to the New Long-Term Emission Regulations. (Engines with the same displacement but different emission reducing technologies and equipped with a hybrid system are counted as constituting different models. Engines for buses but used in trucks are counted as belonging to the same model as the engines for buses.) (2) All diesel engines for HDV adopt NOx catalyzing or DPF as a fullscale after-treatment technology. Also, most of these engines are combined with common-rail fuel injection, VG turbocharging, cool EGR and continuous control technologies. (3) Regarding after-treatment technologies, 3 large engine models have a urea SCR system, one small engine model an NOx storage catalyst, and 22 engine models a DPF. 23
3. Technologies for Compliance to Post-New Long-Term Regulations 24
Technological Approach to Post-New Long-Term Regulations (1) Reduce PM and NOx at engine outlet levels by improving combustion with high-pressure injection, cool EGR, etc.; apply after-treatment (DPF, NOx catalysts) to further reduce below the limit values. (2) Candidate NOx catalysts under consideration are SCR and storage-reduction catalysts. (3) To upgrade the DPF and NOx catalyst and other after-treatment systems, not only advance the performances of catalysts but also optimize exhaust conditions such as exhaust temperature and oxygen concentration, which will require even more sophisticated engine control. 25
DPF + Urea Selective Catalytic Reduction System : Technological challenges for Post-New Long-Term Reg. Improve EGR cooler capacity Upgrade mass EGR & control Up fuel injection pressure (to over 2000 atm) Improve radiator capacity Improve intercooler capacity Intake air Size down DPF & up trapping capacity Upgrade electronic turbo & control Improve urea solution injection control Urea solution tank P Exhaust Size down SCR & improve NOx reducing performance at low temperatures (The catalyst bed temperature is low because SCR is positioned downstream of DPF.) Urea solution servicing infrastructure is a must for spreading SCR to light/medium trucks. 26
DPF + NOx Storage-Reduction Catalyst System : Technological challenges for Post-New Long-Term Reg. Upgrade mass EGR & control Intake throttle Improve radiator capacity Up fuel injection pressure 高圧コモンレール (over 2000 atm) Reduce fuel consumption Improve インタークーラ intercooler Improve NOx reducing capacity ( 給気冷却器 ) performance & reliability at low temperatures Reduce the use of precious Improve EGR EGRクーラ metals cooler capacity Intake air Exhaust Upgrade electronic turbo & control Fuel exhaust feeder 27
Ma ajor Comp ponents Re levant Fac ctors PM reduction NOx reduction Pertinent items Prospective After-Treatment Systems for Post-New Long-Term Regulations DPF + Storage-reduction ti catalyst DPF + Urea SCR PM filter Ceramic filter Forced regeneration device Common-rail, etc. NOx catalyst Storage-reduction catalyst Urea SCR Reducing agent Fuel (diesel) Urea solution Reducing agent feeder Fuel feeding valve Urea solution feeder Reducing agent tank Not necessary Urea solution tank Economic effects (on fuel economy, etc.) Cost Mountability, Mass Fuel economy decline due to exhaust pressure boost and fuel addition Use of expensive precious metals for catalysts Impaired mountability due to enlarged after-treatment system Fuel economy decline due to exhaust pressure boost + Urea solution feeding expense Requirement of additional onboard components related to urea solution (tank, anti-freeze device, etc.) Impaired mountability due to enlarged after-treatment system and additional components related to urea solution Infrastructure Not necessary Necessary* * For light/medium diesel vehicles with urea SCR, urea solution should be made available at service stations. 28
The long, winding road to exhaust emission control... Thank you. 29