In 2010, diesel engine manufacturers set a precedent when many of them added urea injection aftertreatments to their exhaust systems. This emissions solution meant another tank of fluid to fill (at about $3.00 per gallon), coolant lines running to a reservoir to keep the urea from freezing, urea injectors and electronics to control them, and an extra catalytic converter to complete the reaction. The result was a system many of you dread—but it has proven to be brutally effective at removing NOx emissions from the tailpipe of diesel trucks.
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We here at Diesel Power think adding this equipment also opened the door to adding water injection on production diesel vehicles, because consumers will be used to the idea of adding an emissions fluid. In order to avoid redundancy, all engineers would have to design is a larger windshield washer tank and two hoses—one spraying the windshield with a water-methanol mix (which it already does today) and the other feeding the engine with components readily available.
Thanks to companies like Snow Performance, we don’t have to wait to buy a new truck with water injection from the factory, because we can add it to any diesel engine right now.
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.
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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.
That’s when Matt Snow, of Snow Performance water-methanol systems, stepped in. Snow Performance worked with Truckee Meadows Community College to see the effect of its MPG-MAX water-methanol injection system on diesel emissions, fuel economy, and performance. Nevada’s Washoe County Air Quality Management Division even supplied grant money to help fund the 5.9L Dodge Cummins test vehicle mounted on a Clayton dynamometer. The school’s interest is to help facilitate diesel students learning the new emissions control technology.
Water-Methanol Injection Test
Platform: ’03 5.9L Cummins 24-valve engine
Specifications: Stock engine with no EGR and Bosch common-rail fuel system (donated by the Chrysler Training Center)
Modifications: Mr. Bob’s Silicone Hoses boost and coolant hoses
Water-methanol Injection System: Snow Performance Part # 49005 Diesel MPG-MAX
Charge Air Cooler: Behr fullsize from an ’04 Freightliner truck
Cooling fans: Flex-a-lite dual-electric fan from Summit Racing behind the radiator, Grizzly B-air Dyno Blower, and two external cooling fans in front of the radiator
Diesel particulate filter: Clean Air Systems (Permit Filter DPF)
Test Equipment
Data logger & software: HiBACK USB data logger and HiBACK USB Level 2 software
Engine dynamometer: Clayton ED15-1000 with electronic load cell
EGT sensors: Auber Instruments six EGT sensors at each exhaust port and six red LED digital readouts
Diesel exhaust analyzer: NOVA Diesel Analyzers (7465 K series portable exhaust analyzer)
Fuel consumption meter with pulsation damper: FloScan (series 8500 fuel log system)
Smoke check diesel opacity tester: Red Mountain Inc. (1060CPCL 1667 meter meets J1667 specifications)
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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.
