© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) Advanced Mobile Source Training Course MS Diesel III. Emission Testing and Diagnostics of Diesel Engines

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 2 Overview This section of the course will discuss: – The purposes for and the characteristics of a good emission test –The development of emission testing for diesel engines –Recent developments in Not-To-Exceed standards and portable emission testing equipment –On-board diagnostics for heavy-duty diesels

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 3 Why Emission Tests? Accurate estimates of emissions are needed to: –Certify that vehicles and engines are designed and built to meet emission standards –Assess the durability of these designs over time –Develop emission factors from in-use vehicles –Support enforcement action against manufacturers –Identify individual high emitters that can be repaired –Evaluate the effectiveness of retrofit programs

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 4 A Good Emission Test A good emission test: –Accurately represents the duty cycle of a vehicle or engine in-use –Accurately measures the pollutants of concern –Is repeatable –Is affordable

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 5 Barriers to Testing Diesels Light duty diesels can use the same chassis procedures as gasoline vehicles but require additional filter procedures to measure particulate High PM levels require more frequent calibration and maintenance of test equipment Engines for heavy-duty and non-road applications operate over vastly different duty cycles Engine bench testing and emission measurement is more complicated and expensive than chassis testing

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 6 Certification Testing Before 1990: –Heavy duty engines were certified with a 13-mode steady-state test –The concentration of each pollutant, the fuel flow, and the power output in each mode were measured –A smoke test was also conducted –Essentially no in-use testing was performed

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 7 Certification Testing After 1990: –The 13-mode test was replaced with a “transient” dynamometer driving cycle –Particulate was collected on filters and weighed –Each engine’s driving cycle was based on a “map” of its capability, that is, its ability to produce a certain amount of power at engine speeds from idle to full open throttle

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 8 The Need for Better Testing In the 1990’s electronically controlled engines defeated emission controls while cruising on the highway In-use smoke testing couldn’t control for the particulates of concern Need to control non-road engines

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 9 Real World vs. Certification Testing

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 10 Real World Emissions

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 11 The “Ultimate” Diesel Emission Test Refer back to the basic requirements: –Accurately reflect actual use –Accurately measure pollutants –Repeatable –Affordable Prevent defeat devices Enable in-use testing

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 12 Recent Developments Standards established for non-road engines Both transient and steady-state tests required An off-cycle test added – NTE (not-to-exceed standard applied to most operating modes) Development of portable emission measurements for in-use testing Complete revision and standardization of heavy-duty certification tests proposed by EPA Development of a world-wide certification test

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 13 NTE Standards and Testing Historically, EPA relied on a defeat device prohibition to help ensure that vehicles and engines would meet standards in use A defeat device is any auxiliary emissions control device (AECD) (electronic, mechanical or otherwise) which reduces the effectiveness of the emission control system that is in effect under the specific test conditions but not in effect under normal operating conditions, except:

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 14 NTE Standards and Testing Except: –If substantially included in the certification test –If needed for protection from accident or damage –If needed for engine starting Implementation of the defeat device regulation often requires case-by-case determinations Electronically controlled engines have many AECDs

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 15 NTE Standards and Testing The NTE standard is applied in addition to the existing certification test cycle and standards and the existing defeat device prohibition NTE expands coverage beyond the driving cycles and ambient temperatures in the certification test It provides certainty to the manufacturers about the acceptability of AECDs NTE can be tested in-use

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 16 NTE Standards and Testing NTE contains several key concepts: –A defined engine operating region (engine speeds and loads) –Defined ambient operating conditions (temperature and altitude) –Defined in-use operating conditions (minimum of 30 seconds duration) –Specified numerical emission limits (1.25 x the primary emission standard)

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 17 NTE Standards and Testing (US EPA)

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 18 NTE Standards and Testing (US EPA)

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 19 NTE Standards and Testing (US EPA)

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 20 Manufacturer In-Use Testing Pilot program in calendar years 2005 and 2006 Minimum of 5 to a maximum of 10 vehicles per engine family All engine families over 1500 sales are tested over a four year period Portable emission measurements of gaseous and particulate emissions Test vehicles from at least two owner sources

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 21 Portable Emission Measurement Design requirements: –Simple installation on a wide variety of vehicles –Unattended operation Weather and tamper proof Low power consumption Remote communication –Multiple measurement capabilities Flow measurement Ambient conditions Engine speed, temperature, etc.

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 22 PEMS – History of Development EPA investigated and developed on-highway application – ROVER Photograph from EPA

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 23 ROVER (US EPA)

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 24 ROVER (US EPA)

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 25 Portable Emission Measurement (US EPA) EPA continued development for non-road applications – SPOT

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 26 Portable Emission Measurement West Virginia University -MEMS measures CO2 and NOx –additional work on particulate with a quartz crystal microbalance Commissioned by the engine manufacturers as a part of the consent decree WVU also operates a portable dynamometer for trucks and buses Capable of simulating up to 55,000 lbs inertia weight and equipped with full scale dilution tunnel

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 27 WVU Transportable Laboratory

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 28 Portable Emission Measurement Ride along vehicle emission measurement system (RAVEM) developed by Engine, Fuel and Emissions Engineering, Inc. Measures gaseous emissions and samples particulate on a filter Recently used in the Mexico City pilot project to retrofit city buses

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 29 RAVEM

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 30 Particle Number Measurement Many different approaches evaluated in the UNECE Particulate Measurement Programme (PMP) Approaches include: –Scanning Mobility Particle Sizer (SMPS) –Electrical Low-Pressure Impactor (ELPI) –Condensation Particle Counter (CPC) –Thermodesorber (TD)

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 31 Particle Number vs. Mass Portable PM mass measurement is still not available (except for RAVEM) Europe has taken the approach of setting a number- based standard – Swiss-based VERT U.S. is still hoping to have an on-board measurement of mass ready for the 2007 manufacturer in-use tests This subject remains under discussion and evaluation

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 32 Heavy-Duty OBD CARB has adopted a rule for heavy-duty OBD to take effect in 2010 Diesel engine monitors: –Fuel system Fuel pressure control Fuel injection quantity Fuel injection timing Closed loop system function –Misfire identify continuous misfire at idle 2013 identify any misfire causing 1.5 x standard increase

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 33 Heavy-Duty OBD Diesel engine monitors –EGR system Detect faults in the flow rate, response rate, and cooling system performance before 1.5 x emissions increase Monitor closed loop system function –Boost pressure control Detect faults before 1.5 x emissions increase –Under and over boost malfunctions –Slow response –Charge air undercooling Monitor closed loop system function

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 34 Heavy Duty OBD Diesel engine emission control technology monitors: –Hydrocarbon catalyst –NOx catalyst (SCR) –NOx adsorber –PM filter Additional monitors: –Exhaust gas sensors, variable valve timing system –Cooling system; PCV system –Electronic components

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 35 Diesel Emission Testing - Summary Testing using an engine dynamometer is the most accurate but very expensive and cumbersome Using a heavy-duty chassis dyno requires a large capital investment, and cannot accommodate most non-road equipment Current and proposed regulations aim to provide complete control across all applications and the entire operating cycle PEMS are under development but appear not to approach the accuracy and repeatability of engine test benches

© 2005 Northeast States for Coordinated Air Use Management (NESCAUM) 36 Go to: Projects/Academy