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New diesel oil mist separator developed: Alfdex separator a joint effort from Haldex, Alfa-Laval targeting vehicular, stationary and marine uses.

Closing diesel engine crankcases is a technology path receiving increased attention as global emissions standards become more stringent. At this point, while there is not a global regulation for closing diesel engine crankcases, there is action in the U.S. and as emissions restrictions tighten around the world, ventilating diesel crankcases to the ambient air is certain to be addressed in future legislation.

In the U.S., the 2007 truck and bus heavy-duty, diesel regulations eliminate the crankcase emission control exception for turbocharged heavy-duty diesel engines. Crankcase emissions from these engines will be treated the same as other exhaust emissions.

For the off-highway markets, the proposed Tier 4 standards may require closed crankcase ventilation, with the possibility that turbocharged engine crankcase emissions may be discharged into the ambient atmosphere. In such cases, crankcase emissions must be measured during emissions testing and added to tailpipe emissions. This proposed standard would be phased in between 2008 and 2014.

With these standards (and others) looming, a pair of manufacturers with a unique position in the world markets, Haldex and Alfa-Laval, have teamed up to develop the Alfdex oil mist separator. In July 2002, the two Swedish headquartered companies announced a technical and commercial cooperation to develop products to clean up diesel crankcase emissions. This is the first result of that cooperative agreement.

In announcing the alliance, the companies said the agreement combines "Alfa-Laval's expertise in separation technology with Haldex's capabilities in enhancing vehicle performance, as well as its manufacturing, marketing and distribution to the vehicular markets."

With Alfdex now entering the market, Haldex will be responsible for sales and marketing globally to the on highway and off-highway markets, In vehicular uses, the separator is targeted at diesels from about 5 to 16 L in displacement. Prototypes are in operation in on-highway uses in the U.S., with production scheduled for early 2005 by Haldex.

Alfa-Laval's focus will be on the medium and slow speed engine markets, primarily for larger marine and power generation applications.

Alfdex is listed as having a separation efficiency of greater than 98 percent under normal driving conditions. It operates over a zero to 130 gpm blow-by gas rate, nominally at 42 gpm and is designed to operate in engine environments from -40[degrees] to 266[degrees]F with separation efficiency optimized for 212[degrees]F.

This, Haldex said, adds installation flexibility as the system can be located near hot engine components such as the turbocharger. The system weighs 4.4 lb. and measures 7.48 in. high and 5.67 in. wide.

A key feature of the separator is that it is sealed for life requiring no maintenance or service during the engine's lifetime. Lifetime is defined as being 20,000 hours or 600,000 miles, depending on the application.

As the system is sealed, no oil is ventilated to the atmosphere and there is no filter to be recycled. Further, the system is not invasive to the engine itself and requires only about 40 to 100 watts of power to operate.

The Alfdex oil mist separator uses centrifugal separation to remove both oil droplets and soot from the vent gas and return them to the oil sump via a drain pipe. The design is based on Alfa Laval's industrial centrifugal separator technology that has been widely used for years.

The separator is driven by an oil turbine that receives oil from surplus pressure engine lube oil flow. The turbine, fitted in the bottom of the homing, drives a centrifugal rotor that has a number of conical discs stacked on top of each other forming the separation volume.

Oil droplets separate out from the gas on to the discs via centrifugal forces. The collected flow is eventually thrown off the disc edges onto the housing wall. The clean gas is guided to the outlet at the bottom and the oil flows down the walls to the drain outlet feeding back to the sump.

In addition to working as a separator, the disc stack also extracts gas from the crankcase, so there is no pressure drop across the unit. An internal pressure control is designed to ensure the crankcase pressure is within a suitable working range, despite potential variations in the inlet manifold.
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Title Annotation:emissions technology
Author:Osenga, Mike
Publication:Diesel Progress North American Edition
Geographic Code:1USA
Date:Feb 1, 2004
Words:703
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