Urea vs Water Meth - Treat it Before or After

Discussion in 'Emissions' started by TheStepChild, Aug 18, 2012.

  1. Here is one of the articles I mentioned in the other thread.

    http://www.dieselpowermag.com/tech/1108dp_the_science_of_diesel_emissions_reduction/

    I dont know where the rest is, I will try to find it. The printed article had the results too.

    Some features from the write - up:


    The NOx Reduction Triad: Urea, Water Injection, and EGR
    The main reason engine designers picked urea injection is because it’s a base that effectively neutralizes more than 90 percent of the acidic nitrogen oxide (NOx) pollutants that leave the engine. NOx forms during uncontrolled high temperatures in the combustion chamber. Urea injection eliminates NOx in the exhaust pipe by converting it to harmless water and nitrogen.

    Water injection, on the other hand, uses an in-cylinder approach to control NOx. Instead of making the pollutants and dealing with them later, as with urea injection—water injection (also known as fumigation) lowers the temperature inside the combustion chamber. Therefore, not so much NOx forms in the first place.

    Exhaust gas recirculation (EGR) is similar to water injection in that it also reduces NOx formation by regulating combustion chamber temperatures. An EGR system introduces oxygen-depleted air (instead of water) into the combustion chamber to regulate cylinder temperatures.

    Water Injection is Nothing New
    Water injection was invented in 1894, and even Rudolf Diesel called for it in his first engines. Could we see it become an alternative to urea and EGR for NOx control? Perhaps. Over the years, we’ve read Society of Automotive Engineer (SAE) papers that describe the benefits of water injection.

    The military even experimented with cooling an engine entirely with water injection, then recovering the water in the exhaust and reusing it in a closed cycle. Overall, these papers all described water injection as having a positive effect on diesel emissions, although we couldn’t find a test that specifically describes water-methanol injection used on our diesel engines.




    Testing and Measurement Procedures
    1. To perform the specialized testing, the school set up the 1. five-gas diesel exhaust emissions infrared tester for HC, CO, CO1. 21. , O1. 21. , and NOx. A long copper exhaust probe was used to dissipate the heat since the engine is in the loaded mode. The opacity meter measured particulate matter (PM), also from the exhaust emissions. The dyno measured engine speed, horsepower, and torque using an electronic load cell.

    2. Additional gauges measure EGT at each cylinder exhaust valve and one sensor after the turbocharger. Boost pressure is measured at the turbocharger outlet and at the intake manifold (checking for any pressure drop through the charge-air cooler). Boost air temperature difference is measured at the inlet and outlet of the intercooler. The boost temperature drop across the intercooler is usually around 200 degrees. Primary fuel pressure is measured after the primary fuel pump ranged around 6 to 10 psi. Fuel consumption in gallons per hour (gph) is measured with sensors at the fuel inlet and return. All the other basic engine test meters, engine oil pressure, coolant temperature, oil temperature, and battery voltage are built in and register any time the engine and dynamometer are running. The Snow performance digital readout confirms boost pressure and EGT.

    3. The test was conducted by raising engine rpm and applying and adjusting for maximum load, while still maintaining an rpm range around 2,200 to 2,300 rpm. If rpm is too high, load is increased. If rpm is too low, load is reduced. There were some tests that ran above and below the rpm range. Each test was run long enough (about 4 minutes) to get stabilized readings, then the load and rpm were reduced to cool the engine and dyno down. During testing, engine coolant temperatures ranged from about 180 to 220 degrees.

    4. To establish a baseline, more than 20 tests were conducted with red diesel at full load. The test data appears to be consistent. The water and methanol injectors were connected directly to the inlet pipe, downstream from the turbocharger and intercooler. So far, their preliminary test data shows some interesting improvements using the water and methanol injected into the intake pipe.


    I found a thread I posted on this on one of the duramax forums, when the article came out. It was in Diesel power mag, Aug 2011. Cant seem to find the entire article online.
     
  2. phoebeisis

    phoebeisis Well-Known Member

    James
    NOx emissions are what sunk Navstar-right?
    They-the boss-bet on EGR to reach the EPAs most stringent requirement
    But it failed.

    They would have tested water injection-heck it is so cheap-why wouldn't they?
    Maybe water injection didn't work well enough at certain throttle settings?

    So why don't the manufacturers use it-is anyone saying "we tried H2O but it didn't... something"
    Certainly couldn't be cost or complexity-low pressure pump-tank of water-little bit of methanol in winter
    It must have failed in some respect-at some load level

    Frankly it is a shame the EPA pushed sooo hard-simply and cheap-hard to beat.
     
  3. That was a quote in the artice too. Basically, 'why aren't the manufacturers using this? Add a bigger windshield washer tank with a second port. One port to windshield and one to engine.'.

    I was surprised, and pleased when I pulled my intake off and saw how clean it was vs other pics I've seen of the intakes. Also ran a flashlight on a flex line and a mirror as far in the intake as I could. Just as clean all the way in.

    Another guy on the dmax forum put in an email to try to get the rest of the article with the full results, and I have a thread asking for a copy of the mag if someone has it laying arond. If I get it I'll post or link it.
     
  4. phoebeisis

    phoebeisis Well-Known Member

    I wonder if water methanol has any effect on "soot"

    Clean intake indicates either less soot- or maybe it is being washed downstream??
     
  5. herm

    herm Well-Known Member

    I think soot is a result of low temperature combustion, so it might be worse.

    Adding a water injection system to a gasoline engine may improve mileage if the computer advances the timing due to no pinging.. it would also lower the density of the incoming air and thus less fuel. Someone on this forum must have experimented with it.
     
  6. RedylC94

    RedylC94 Well-Known Member

    Soot is a result of fuel particles that didn't find sufficient air to burn cleanly. Thus the heavy smoke from old diesels (especially non-turbocharged ones) that were injecting too much fuel under heavy load, and also from engines with faulty injector spray patterns.
     
    Last edited: Aug 21, 2012

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