Bradley edgar asks “How’s Your Aftertreatment Treating You?” Print
Friday, December 07, 2018 09:25 AM

Bradley Edgar asks “How’s Your Aftertreatment Treating You?”

LOUISVILLE, KY – News updates, trends, market projections, innovations, design and new cleaning techniques, it doesn’t get any better for the DPF crowd assembled for the HD Conference here in September. Dr. Bradly Edgar of Red Fox Resources returned to the NARSA podium after his debut last year in Buffalo with a presentation chock full of knowledge.

Bradley Edgar has been involved in emissions for twenty-plus years and holds a Ph.D. in mechanical engineering with focus on combustion, heat transfer and air pollution. His best asset is his ability to deliver technical and business information in a manner that is easily understandable.

Among the news items, certainly booming truck sales is at the top of every truckers list. Since the meeting, ACT Research says over the past 12 months Class 8 orders have totaled 503,500 units. The last record year was 2006, when the build reached 376,000 units. That is good news. Really good news is that all have diesel emissions aftertreatment systems.

Maybe not such good news is that all the truck makers have electric truck programs in the works.

Brad also pointed out that now gasoline particulate filters are in production in Europe for light duty vehicles. He said these gasoline particulate filters (GPFs) are very similar in design and function, but smaller.

He pointed out the “sweet spots for service” are the larger trucks with serviceable DPFs which he estimated to be 2.6 million engines in 2018 but projected to reach 12.5 million by 2027 when the market reaches maturity. He told them, “Future trends . . . are here.” That includes:

  • more compact designs;
  • DOC, DPF and SCR integrated into single package;
  • SCR is becoming more effective;
  • SCR catalysts may be coated on DPF;
  • extended cleaning intervals with better oil control;
  • sensors and On-Board Diagnostics continue to improve.

He went on to provide a detailed look into the evolution of the technology, differences in the designs, and the fundamental concepts of cleaning. His comments on thermal and air-cleaning included:

  • Temperature ramps and ranges
    • (212-572°F): coolant, water, oil, fuel starts to evaporate
    • (1100-1200°F): soot oxidizes
  • Watch outs
    • Vaporized fluids are smelly and can create a mess
    • Too much soot, or oil soaked DPF can ‘runaway’ and lead to overheating, melting or fire
    • Load parts so they can entrain air (vertical is best)
  • Multiple steps and sequence can be important
    • Blow-Bake-Blow again: First blow cycle removes excess carbon
    • Bake-Blow-Bake again: Ash plugs can trap carbon and keep oxygen from getting to soot
  • Weigh parts before and after each step - Measuring weight/flow at each step is good practice
    • Lots of soot: could be engine problem - Lots of ash: oil control or too long between cleaning
    • Lots of oil/coolant: leaking/failed turbo, fuel injector, EGR cooler
  • Pay attention and take good notes
    • There is a learning curve

Adding perspective to the DPF development, Edgar provided a brief history. From 1980 to 2000, engine makers considered a number of different designs which resulted in a variety of materials and regeneration strategies were considered. He said the earliest applications were in underground mining.

By the 2000’s, the wall flow filter be- came the design of choice. It was also around then that California and EPA sponsored voluntary and regulated retrofit pro- grams. By 2007, the level of permitted particulate matter was reduced by 90% and that meant DPF technology would be required. DPF regeneration was based on catalyst technology with engine management. In 2010, NOx mandated reductions insured that urea SCRs were required. DPF regeneration became easier.

DPF design has settled. Materials used include: cordierite, silicon carbide, aluminum titanate. Leading manufacturers include: Corning, NGK and Ibiden.

Dimensions are from 6 to 13 inches in diameter with lengths from 6 to 15 inches, and cell density of 200-300 cells/in2 (cpsi). Today’s DPFs feature high filtration area per volume, high filtration efficiency (98 per- cent of particles), low pressure drop, high melting point, low thermal expansion, and can be coated with catalyst. According to Edgar, wall flow designs seemed to be here to stay for a while.

Serviceable DPFs are fastened with gas- kets and seals. Filters for Class 4-6 are more difficult to clean and in some cases non- serviceable. Filters for Class 2-4 engines, are not designed for cleaning. DPF clean- ing basic tools and processes include:

  • Heat to oxidation temperature of carbon (baking);
  • Reverse backflow of compressed air (blow);
  • Aqueous cleaning: water jet, flush/irrigate, ultrasonic;
  • Combination of methods usually required.

Edgar outlined current filter diagnostics in play which include:

  • Scale for weight;
  • Flow bench for pressure drop;
  • Pin test for cell blockage;
  • Ultrasonic device for cracks;
  • Borescope;
  • Light test.

Edgar pointed to the parts and service opportunities that cleaning can provide. They include: service revenue; aftermarket DPF/DOC sales; replacement parts sales (DPFs, gaskets, clamps); upstream engine work; and income from parts recycling.