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Conference report: US DOE 2013 Merit Review

30 July 2013

With the cancellation of the 2013 DEER conference, there will be fewer opportunities to keep up-to-date on the progress of DOE sponsored projects related to engine-emissions and efficiency. One alternative is the Annual Merit Review and Peer Evaluation Meeting that is normally held in May in the Washington, DC area. The Annual Merit Review provides a forum for evaluation and discussion of the Vehicle Technologies Office's projects where reviewers evaluate the projects' contributions to the program's mission and goals. The recommendations from the reviewers are taken into consideration by DOE in generating future work plans. Summaries of the comments appear in an annual progress report, which are posted on the Vehicle Technologies Office website's Annual Progress Reports page. This year’s results will be published by October 1, 2013.

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The presentations from this year’s meeting, already posted, reflect the variety of projects sponsored by DOE. The topics areas included: combustion and emissions control, vehicles and systems, fuels and lubricants, propulsion materials, solid state energy conversion, and power electronics and electric motors. Several industry-led projects that were discussed this year included the SuperTruck program and projects targeting fuel consumption improvements for light-duty vehicles meeting Tier 2 Bin 2 SULEV emissions.

SuperTruck. Since the last update in October 2012, a clearer picture is emerging on what will be required to reach the 50% BTE objective. Common among the participants is a goal to achieve a 47.5 - 48.0% BTE from the engine alone and recover enough waste heat to bring the final BTE to 50% or higher. Critical to maximizing the engine’s efficiency is the application of SCR aftertreatment to control NOx. At least two approaches have emerged on this front: (1) an approach that allows engine-out emissions of 3-5 g/bhp-hr coupled to a high efficiency (over 95%) SCR that brings NOx below 0.20 g/bhp-hr and (2) an approach that brings engine-out NOx to below 1 g/bhp-hr and uses a moderate SCR efficiency of > 80% to hit the required NOx emissions.

Cummins’ program is based on downspeeding their 15 L engine and they have already exceeded the 50% BTE by a comfortable margin. A 51.1% BTE has been demonstrated that breaks down to a 47.5% contribution from the engine and 3.6% from heat recovery. Compared to progress reported at DEER 2012, the goal has been achieved by increasing the engine’s gross indicated efficiency through and expanding the waste heat recovery to recover energy from the coolant. Cummins WHR turbine is mechanically coupled to the crankshaft and also recovers exhaust and EGR waste heat. SET cycle weighted engine-out emissions increased to 4.3 g/bhp-hr from the 3.5 g/bhp-hr reported previously. To reach a system out NOx of 0.08 g/bhp-hr, SCR efficiency needs to be about 98% [Koeberlein].

Light-Duty Fuel Efficiency. A number of programs aim to improve the fuel efficiency of various light-duty vehicles while meeting LEV III/Tier 3 emission limits.

Cummins’ ATLAS program that is developing a diesel engine for light-duty truck applications, has focused on transferring technology developed on a mule to a new engine. A T2B5 vehicle demonstration planned for end of 2013 with a T2B2 demonstration to follow mid-2014. Hydrocarbon emissions have been a challenge and are being addressed with Johnson Matthey’s cold start catalyst (CSC) that adsorbs HC and NOx after a cold start and releases them after the other aftertreatment components have warmed up sufficiency to achieve high conversion efficiency. The CSC followed immediately by a DPF coated with an SCR catalyst (SCRF) are close coupled to the engine. An Amminex direct ammonia reductant system is being used. In addition to cold starting benefits, the direct ammonia system more easily allows multiple ammonia dosing locations—an additional dosing location is being considered between the SCRF and additional underfloor SCR catalysts to mitigate emissions during filter regeneration [Ruth].

Source: US DOE Merit Review