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Cold-Start WHTC and WHSC Testing Results on Multi-Cylinder Opposed-Piston Engine Demonstrating Low CO2 Emissions while Meeting BS-VI Emissions and Enabling Aftertreatment Downsizing

SAE International Journal of Advances and Current Practices in Mobility

Achates Power Inc-Abhishek Sahasrabudhe, Fabien Redon, David Johnson, Laurence Fromm, John Headley
BASF-David Youngren
  • Journal Article
  • 2019-26-0029
Published 2019-01-09 by SAE International in United States
Reducing the greenhouse emissions from on-road freight vehicles to meet the climate change mitigation objectives, has become a prime focus of regulatory authorities all over the world. Besides India, the United States, the European Union, Canada, Japan, and China have already established or planned heavy-duty vehicle efficiency regulations addressing CO2 and NOX emissions. In addition, Argentina, Brazil, Mexico, and South Korea are all in various stages of developing policies to improve the efficiency of their commercial vehicle fleets. For CO2 emissions reduction standards, the U.S. mandates 27% reduction by 2027, EU is calling for 15% reduction by 2025, China for 27% by 2019 over 2012 levels, and India is mandating 10%-15% reduction by 2021 for phase 2 of the new standard. There has also been considerable focus on further reduction in NOX emissions from current levels (0.2 g/hp-hr), to the proposed ultra-low NOx standards (0.02 g/hp-hr) in the U.S. for heavy duty engines by 2024.Given these planned and proposed regulatory standards being implemented around the globe, there have been substantial studies and publications focusing on…
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Cold Start HD FTP Test Results on Multi-Cylinder Opposed-Piston Engine Demonstrating Rapid Exhaust Enthalpy Rise to Achieve Ultra Low NOx

Achates Power Inc-Fabien Redon, Dan Schum, John Headley
Achates Power Inc.-Samrat Patil, Ahmad Ghazi
Published 2018-04-03 by SAE International in United States
The 2010 emission standards for heavy-duty diesel engines in the U.S. have established a limit for oxides of nitrogen (NOx) emissions of 0.20 g/bhp-hr., a 90% reduction from the previous emission standards. However, it has been projected that even when the entire on-road fleet of heavy-duty vehicles operating in California is compliant with the 2010 emission standards, the upcoming National Ambient Air Quality Standards (NAAQS) requirement for ambient particulate matter and ozone will not be achieved in California without further significant reductions in NOx emissions from the heavy-duty vehicle fleet. Given this, there is potential of further reduction in NOx emissions limit standards for heavy duty engines in the US. Recently there have been extensive studies and publications focusing on ultra-low NOx after treatment technologies that help achieve up to 0.02g/bhp-hr. at tailpipe [1].To achieve ultra-low NOx emission levels over the composite HD FTP cycle, rapid heat energy must be provided to the diesel exhaust after-treatment system during cold start portion of the cycle, and peak NOx reduction efficiency must be maintained during the hot-start…
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Developing a 55% BTE Commercial Heavy-Duty Opposed-Piston Engine without a Waste Heat Recovery System

Achates Power Inc-Nishit Nagar, Rodrigo Zermeno, Michael chiang, Isaac Thomas
Achates Power Inc.-Neerav Abani
Published 2017-03-28 by SAE International in United States
Heavy-duty vehicles, currently the second largest source of fuel consumption and carbon emissions are projected to be fastest growing mode in transportation sector in future. There is a clear need to increase fuel efficiency and lower emissions for these engines. The Opposed-Piston Engine (OP Engine) has the potential to address this growing need. In this paper, results are presented for a 9.8L three-cylinder two-stroke OP Engine that shows the potential of achieving 55% brake thermal efficiency (BTE), while simultaneously satisfying emission targets for tail pipe emissions. The two-stroke OP Engines are inherently more cost effective due to less engine parts. The OP Engine architecture presented in this paper can meet this performance without the use of waste heat recovery systems or turbo-compounding and hence is the most cost effective technology to deliver this level of fuel efficiency.In this paper, engine performance results are presented for the 9.8L two-stroke OP Engine that employs currently available engine components, such as supercharger, turbocharger and after-treatment and features a uniquely designed piston bowl shape to enhance mixing with a…
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Multi-Cylinder Opposed-Piston Engine Results on Transient Test Cycle

Achates Power Inc-Arunandan Sharma, Fabien Redon
Published 2016-04-05 by SAE International in United States
After having tested basic transient maneuvers such as load-step changes on the 4.9L three-cylinder opposed-piston diesel engine [1], a similar test-engine was subjected to a more aggressive test-routine - a hot-start heavy-duty FTP (Federal Test Procedure) transient cycle for the on-road engines. The three main objectives of this exercise were:1To assess the ability of the engine to meet the transient cycle requirements while maintaining close to the cycle-average BSFC for the FTP cycle derived from steady-state torque-to-fuel map.2To attain engine-out brake-specific emission levels that are compatible with US2010 EPA requirements with a conventional after-treatment system consisting of a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF) and a selective catalyst reduction (SCR) system.3To compare hot-start FTP transient cycle fuel economy with a publicly available benchmark.The initial results from the test are encouraging - the BSFC value is within 1.2% of the value derived from running FTP cycle on a steady-state torque-to-fuel map. The engine-out emissions (BSNOx and BSSoot) levels generated during the test are compatible with US2010 EPA tail-pipe emissions requirements and can be…
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Multi-Cylinder Opposed Piston Transient and Exhaust Temperature Management Test Results

Achates Power Inc-Fabien Redon, Arunandan Sharma, John Headley
Published 2015-04-14 by SAE International in United States
In a recent paper, Opposed-Piston 2-Stroke Multi-Cylinder Engine Dynamometer Demonstration [1] published at the SAE SIAT in India in January 2015, Achates Power presented work related to the first ever opposed piston multi-cylinder engine fuel economy demonstration while meeting US 2010 emissions.The results showed that the research 4.9L three cylinder engine was able to achieve 43% brake thermal efficiency at the best point and almost 42% on average over the 12 modes of the SET cycle. The results from this test confirmed the modelling predictions and carved a very robust path to a 48% best BTE and 46.6% average over the cycle for a production design of this engine.With the steady state performance and emissions results achieved, it was time to explore other attributes.In this second paper, the OP engine transient capabilities were assessed by testing the engine performance and emissions response under a typical transient maneuver: 25% to 100% load step at low and constant engine speed. It can be seen that during such transition, it is possible to control both NOx and Soot…
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Opposed-Piston 2-Stroke Multi-Cylinder Engine Dynamometer Demonstration

Achates Power Inc-Suramya Naik, Fabien Redon, Gerhard Regner, John Koszewnik
Published 2015-01-14 by SAE International in United States
With mounting pressure on Indian manufacturers to meet future fuel economy and emissions mandates-including the recently passed Corporate Average Fuel Consumption (CAFC) standards for light-duty vehicles-many are evaluating new technologies. However, to provide an economically sustainable solution, these technologies must increase efficiency without increasing cost.One promising solution to meet both current, and future, standards is the opposed-piston engine. Widely used in the early 20th century for on-road applications, use of the opposed-piston engine waseventually discontinued due to challenges with emissions and oil control. But advancements in computer-aided engineering tools, combined with state-of-the-art engineering practices, has enabled Achates Power to develop a modern opposed-piston diesel engine architecture that is clean, significantly more fuel efficient and less expensive to manufacture than today's four-stroke engines.In addition to a short explanation of the opposed-piston engine and its inherent efficiency benefits, this technical paper will provide detailed performance and emissions results of a multi-cylinder Achates Power opposed-piston engine configured to meet commercial truck requirements. These results, which will be presented for the first time in India, demonstrate the engine's ability…
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Practical Applications of Opposed-Piston Engine Technology to Reduce Fuel Consumption and Emissions

Achates Power Inc-David Johnson, John Koszewnik, Laurence Fromm, Fabien Redon, Gerhard Regner, Kevin Fuqua
Achates Power, Inc.-Suramya Naik
Published 2013-11-27 by SAE International in United States
Opposed-piston (OP) engines have attracted the interest of the automotive industry in recent years because of their potential for significantly improved fuel economy. Opposed-piston, two-stroke (OP2S) engine technology amplifies this fuel efficiency advantage and offers lower cost and weight due to fewer parts.While OP engines can help automotive manufacturers comply with current, and future, efficiency standards, there is still work required to prepare the engines for production. This work is mainly related to packaging and durability.At Achates Power, the OP2S technology is being developed for various applications such as commercial vehicles (heavy-and medium-duty), SUVs, pick-up trucks and passenger cars (i.e. light-duty), military vehicles, large ships and stationary power (generator sets).Included in this paper is a review of the previously published OP engine efficiency advantages (thermodynamics, combustion and air system) as well as the architecture's historical challenges. Also included is: 1An overview of the packaging-related challenges of OP2S engines using opportunities with the dual-crank, Junkers Jumo-style design with power take-out options, vertical engine installation and bore-to-bore distance.2Different design parameters of the OP2S engine and their optimization…
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Cylinder Cooling for Improved Durability on an Opposed-Piston Engine

Achates Power Inc-Michael Wahl
Achates Power Inc.-Patrick Lee
Published 2012-04-16 by SAE International in United States
The cooling system design for a two-stroke, opposed-piston (OP) engine is substantially different from that of a conventional four-stroke engine as the opposed-piston engine requires efficient cooling at the center of the cylinder where the heat load is highly concentrated. A thermally efficient design ensures engine durability by preserving the oil film at the top ring reversal zone. This is achieved by limiting the surface temperature of the liner to below 270°C at this location. Various water jacket designs have been analyzed with computational fluid dynamics (CFD) using a "discretized" Nusselt number approach for the gas side heat flux prediction. With this method, heat transfer coefficients are computed locally given the flow field of the combustion gases near the liner surface and then multiplied by the local gas/liner temperature difference to generate the heat flux distribution into the cylinder liner. The heat flux is then averaged over the cycle before being applied as a boundary condition to the CFD simulation. The baseline design consists of a simple water jacket with coolant flowing axially from the…
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The Achates Power Opposed-Piston Two-Stroke Engine: Performance and Emissions Results in a Medium-Duty Application

SAE International Journal of Engines

Achates Power Inc-Gerhard Regner, Randy E. Herold, Michael H. Wahl, Eric Dion, Fabien Redon, David Johnson, Brian J. Callahan, Shauna McIntyre
  • Journal Article
  • 2011-01-2221
Published 2011-09-13 by SAE International in United States
Historically, the opposed-piston two-stroke diesel engine set combined records for fuel efficiency and power density that have yet to be met by any other engine type. In the latter half of the twentieth century, the advent of modern emissions regulations stopped the wide-spread development of two-stroke engine for on-highway use. At Achates Power, modern analytical tools, materials, and engineering methods have been applied to the development process of an opposed-piston two-stroke engine, resulting in an engine design that has demonstrated a 15.5% fuel consumption improvement compared to a state-of-the-art 2010 medium-duty diesel engine at similar engine-out emissions levels. Furthermore, oil consumption has been measured to be less than 0.1% of fuel over the majority of the operating range. Additional benefits of the opposed-piston two-stroke diesel engine over a conventional four-stroke design are a reduced parts count and lower cost.
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