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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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Achieving Bharat Stage VI Emissions Regulations While Improving Fuel Economy with the Opposed-Piston Engine

SAE International Journal of Engines

Achates Power, Inc.-Suramya Naik, David Johnson, Laurence Fromm, John Koszewnik, Fabien Redon, Gerhard Regner, Neerav Abani
  • Journal Article
  • 2017-26-0056
Published 2017-01-10 by SAE International in United States
The government of India has decided to implement Bharat Stage VI (BS-VI) emissions standards from April 2020. This requires OEMs to equip their diesel engines with costly after-treatment, EGR systems and higher rail pressure fuel systems. By one estimate, BS-VI engines are expected to be 15 to 20% more expensive than BS-IV engines, while also suffering with 2 to 3 % lower fuel economy. OEMs are looking for solutions to meet the BS-VI emissions standards while still keeping the upfront and operating costs low enough for their products to attract customers; however traditional engine technologies seem to have exhausted the possibilities. Fuel economy improvement technologies applied to traditional 4-stroke engines bring small benefits with large cost penalties.One promising solution to meet both current, and future, emissions standards with much improved fuel economy at lower cost is the Opposed Piston (OP) engine. Recently, there has been surge in developing highly efficient OP engine architecture to modernize it using today’s analytical tools, high pressure fuel system and manufacturing technologies to meet emissions, while reaping the fuel economy…
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Effects of Injection Pattern Design on Piston Thermal Management in an Opposed-Piston Two-Stroke Engine

Achates Power Inc.-Rishikesh Venugopal, Neerav Abani, Ryan MacKenzie
Published 2013-09-24 by SAE International in United States
This paper presents analytical and measured results on the effects of injection pattern design on piston thermal management in an Opposed-Piston, Two-Stroke (OP2S) diesel engine. The OP2S architecture investigated in this work comprises two opposing pistons forming an asymmetric combustion chamber with two opposing injectors mounted on the cylinder wall. This unique configuration offers opportunities to tailor the injection pattern to control the combustion heat flux and resulting temperatures on the piston surfaces while optimizing combustion simultaneously. This study utilizes three-dimensional (3D) computational fluid dynamics (CFD) with state-of-the-art spray, turbulence and combustion models that include detailed chemistry to simulate the in-cylinder combustion and the associated flame/wall interactions. In addition, the measurements comprise a real-time thermocouple system, which allows for up to 14 locations to be monitored and recorded on the intake and exhaust pistons.The CFD results are shown to predict the measured performance and emissions characteristics with very good correlation. Using the CFD model results, hot spot areas on the piston surfaces-resulting from impingement of the injection plumes during the combustion event-are computed. A proprietary…
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Gaseous Fuel Injection Modeling Using a Gaseous Sphere Injection Methodology

Lawrence Livermore National Laboratory-Salvador M. Aceves, Daniel L. Flowers
University of Wisconsin-Madison, Engine Research Center-Randy P. Hessel, Neerav Abani
Published 2006-10-16 by SAE International in United States
To facilitate the growing interest in hydrogen combustion for internal combustion engines, computer models are being developed to simulate gaseous fuel injection, air entrainment and the ensuing combustion. This paper introduces a new method for modeling the injection and air entrainment processes for gaseous fuels. Modeling combustion is not covered in this paper. The injection model uses a gaseous sphere injection methodology, similar to liquid droplet injection techniques used for liquid fuel injection. In this paper, the model concept is introduced and model results are compared with correctly- and under-expanded experimental data.
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Use of a Pressure Reactive Piston to Control Diesel PCCI Operation - A Modeling Study

Engine Research Center, University of Wisconsin-Madison-Achuth Munnannur, Neerav Abani, Rolf D. Reitz
Published 2006-04-03 by SAE International in United States
The heavy-duty diesel engine industry is required to meet stringent emission standards. There is also the demand for more fuel efficient engines by the customer. In a previous study on an engine with variable intake valve closure timing, the authors found that an early single injection and accompanying premixed charge compression ignition (PCCI) combustion provides advantages in emissions and fuel economy; however, unacceptably high peak pressures and rates of pressure-rise impose a severe operating constraint. The use of a Pressure Reactive Piston assembly (PRP) as a means to limit peak pressures is explored in the present work. The concept is applied to a heavy-duty diesel engine and genetic algorithms (GA) are used in conjunction with the multi-dimensional engine simulation code KIVA-3V to provide an optimized set of operating variables. Different sets of PRP parameters (viz. preload, spring constant, damping coefficient and crown mass) were used in an optimization study and the effects of intake valve closure timing, start-of-injection timing, injection duration and exhaust gas recirculation were investigated. The results show that in cases when the…
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Modelling of Spray and In-cylinder Air Flow Interaction in Direct-Injection Engines

Department of Mechanical Engineering Indian Institute of Science Bangalore-560012-Neerav Abani, Shamit Bakshi, R. V. Ravikrishna
Published 2001-11-01 by The Automotive Research Association of India in India
A model is developed based on Lagrangian-drop and Eulerian-fluid procedure to simulate fuel spray structure and the interaction of spray with in-cylinder gas motion. The hollow cone spray is modeled assuming the sheet consisting of blobs of droplets and these blobs are further subjected to secondary breakup. The droplet equations of position, momentum and temperature have been solved by the fourth order Runge-Kutta scheme. The gas phase compressible flow is solved using the finite volume method in conjunction with the SIMPLEC algorithm. The coupling between gas phase and the liquid phase has been achieved through the source terms arising in each phase. Three-dimensional spray and interaction with air motion inside the cylinder have been performed. The results show that the spray structure is well simulated. The model predicts the entrained air velocities and the fuel vapour concentration distribution as a function of time.
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