Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Diesel Engine Exhaust

  1. Jan 1, 2009 #1
    Hi, everyone.
    Again....I meet some problem in my work.
    My boss want to reduce the exhaust soots from a Euro 0/1 engine.

    Here is the problem:
    1. If I use conventional DPF, how can i know the radius and the length of the DPF filter required for the engine? (The exhaust gas CFM is known)

    2. If I cannot use DPF due to buget, can i use a wet centrifugal scrubber to remove the soot? (Wiki said scrubber can remove 1um's particulate efficiently, is it ture?)

    3. Is there any equation for me to use to design the wet scrubber? (any existing webpage?)

    The only objective is to make the smoke looks cleaner (only the visiabiliy).

    Thank you very much for your help.
  2. jcsd
  3. Jan 2, 2009 #2


    User Avatar
    Science Advisor
    Gold Member

    I'd ask for some more info here. What sort of engine is this? What conditions is it operating under? Visible smoke can often be easily reduced/eliminated without having to look at aftertreatment.
  4. Jan 2, 2009 #3
    That's an heavy loading diesel engine; Cat 3306 for an portable air compressor.
    The power rateing is 2XX Hp; exhaust at 900'C and 1700 CFM.
    The exhaust temp at the outlet is reduced to 300'C already.

    Can u suggest some methods to reduce visible smoke?
  5. Jan 3, 2009 #4


    User Avatar
    Science Advisor
    Gold Member

    The engine is rated at 200hp, is that where you're seeing the problem? I guess this is black smoke? Has the engine always smoked? How old is the engine? How many hours? Has it been serviced regularly? Is it turbocharged?

    You might reduce smoke by swinging the timing a bit, but beware of cylinder pressures and exhaust temperatures.
  6. Jan 3, 2009 #5
    Thanks for your reply, brother brewnog.

    Actually, there is black smoke but not very serious (very light grey in color; continuously and it is common for old standard engine).
    Those 3306 (250HP) series engines had run for 10-16yrs.
    All kind of lubrication oil/ filters are replaced regularly.
    Yes, most diesel are turbo charged.

    Since they are Euro0/1 engine , PM emission is not good.
    My problem is finding a cheap way to fix the PM problem.
    The current proposal of my boss is using an heat exchanger to coll the exhaust to suitable temp. + a paper filter bag at cooler outlet.

    I believe this config. is not practicable since the cooler is very large and the soot will stick on the bag = = which mean frequent replacement is need and it cost lots of money.
  7. Jan 3, 2009 #6


    User Avatar
    Science Advisor
    Gold Member

    Thanks for the extra info. I think trying to catch the PM in a paper bag is a nice idea but almost certain to fail; if it were that easy DPF technology wouldn't be where it is now. With those volume flow rates you'll very quickly clog/burst/burn the bag anyway.

    I asked about turbocharging because they could be the cause; how many hours has the engine done since the turbo was replaced? I assume you've checked the entire air inlet system for any air/boost leaks, and that the air cleaner restriction is low?
  8. Jan 4, 2009 #7
    Thanks for your reply.

    I would ask, Is it ture that Euro0/1 engine can still work without smoke? The allowable emission value for them is quite large.

    U mean the whole turbo should be replaced regularly? Can u tell me the reason?
    Those turbos and the whole engine will be overhaul one times per 3 years.

    I think the air cleaner restriction is not a problem. Since we have used the manufacturer's filter as required.

    Btw, is there any suggestion to after-treament other to DPF?

  9. Jan 4, 2009 #8


    User Avatar
    Science Advisor
    Gold Member

    A well-serviced, highly loaded Euro 1 engine should produce next to no visible smoke. (Cold or off load is a different matter).

    Turbos are typically a service item for highly rated industrial engines (either replacement or cleaning). Turbo shafts wear, the bearings wear, the seals wear, and sometimes the compressor and turbine wheels start to acquire deposits which can cause catastrophic failure. Take a look at the service book (should be in Cat's Operating and Maintenance Manual) for the service schedules for this engine.

    A DPF is the usual solution for reducing PM, but it will only work if the engine is in a good operating condition. Particulate matter can be reduced significantly (without aftertreatment) by adjusting fuelling rate, injection timing, injection pressure, EGR and AFR (by these means the particulates are burnt in-cylinder, or early on in the exhaust system) but the tradeoff is that cylinder temperatures and pressures increase, and NOx goes right up.

    When you're only really concerned about reducing visible smoke, a DPF is probably overkill, and I'd definitely start by optimising the fuel injection system first.
  10. Jan 5, 2009 #9
    Thanks again for your kind help.
    I am afraid adjusting the fueling rate, timeing is out of my technical knowledge. As far as i know, Euro 0 /1 are still using mechanical injection. There is not much for me to do with them.
    Even if they have an ECU (some of my new engines Euro 3/4), my company can't get the maintanence software from the manufacturer. Thus, I believe the problem goes back to the starting point, after burnt treament.

    Do you have any suggestions? Thanks for your help.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook