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Evaluation of Zero Oil Cooling for Improved BTE in a Compression Ignition Engine

Southwest Research Institute-Bradley Denton, Edward Smith, Jason Miwa, Daniel Christopher Bitsis
  • Technical Paper
  • 2020-01-0284
To be published on 2020-04-14 by SAE International in United States
With increasing diesel engine emissions regulations and the desire to increase overall thermal efficiency of the engine, various combustion concepts have been explored. One of the potential pathways to higher efficiency is through reduction of in-cylinder heat transfer. In this paper, a concept aimed at decreasing in-cylinder heat transfer through increased piston temperature is explored. In order to increase piston temperature and ideally reduce in-cylinder heat transfer, a Zero-Oil-Cooling (ZOC) piston concept was explored. To study this concept, the test engine was modified to allow piston oil cooling to be deactivated so that its impact on parameters such as BTE, piston temperature, and emissions could be evaluated. The engine was equipped with in-cylinder pressure measurement for combustion analysis as well as a piston temperature telemetry system to evaluate piston crown temperature. This paper will discuss the process by which the engine was modified to achieve ZOC and tested. Engine and piston telemetry data with and without oil cooling will be shown to demonstrate the impact on brake thermal efficiency and piston temperatures.
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Evaluation of Diesel Spray with Non-Circular Nozzle - Part I: Inert Spray

Southwest Research Institute-Khanh Cung, Ahmed Abdul Moiz, Bansal Shah, Vickey Kalaskar, Jason Miwa, Zainal Abidin
Published 2019-01-15 by SAE International in United States
Numerous studies have characterized the impact of high injection pressure and small nozzle holes on spray quality and the subsequent impact on combustion. Higher injection pressure or smaller nozzle diameter usually reduce soot emissions owing to better atomization quality and fuel-air mixing enhancement. The influence of nozzle geometry on spray and combustion of diesel continues to be a topic of great research interest. An alternate approach impacting spray quality is investigated in this paper, specifically the impact of non-circular nozzles. The concept was explored experimentally in an optically accessible constant-volume combustion chamber (CVCC). Non-reacting spray evaluations were conducted at various ambient densities (14.8, 22.8, 30 kg/m3) under inert gas of Nitrogen (N2) while injection pressure was kept at 100 MPa. Shadowgraph imaging was used to obtain macroscopic spray characteristics such as spray structure, spray penetration, and the spray cone angle. Analysis from image processing showed expected result of lower penetration rate and higher spray cone angle as ambient density increased. Two slot nozzles with different aspect ratios but similar flow area as compared with one…
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FSI - MRF Coupling Approach For Faster Turbocharger 3D Simulation

SAE International Journal of Advances and Current Practices in Mobility

Convergent Science Inc.-Jasim Sadique, Yunliang Wang
Southwest Research Institute-Zainal Abidin, Andrew Morris, Jason Miwa
  • Journal Article
  • 2019-01-0007
Published 2019-01-15 by SAE International in United States
Fluid-Structure Interaction (FSI) simulation approach can be used to simulate a turbocharger. However, this predictive 3D simulation encounters the challenge of a long computational time. The impeller speed can be above 100,000 rpm, and generally a CFD solver limits the maximum movement of the impeller surface per time step. The maximum movement must be a fraction (~0.3) of the cell length, thus the time step will be very small. A Multiple Reference Frame (MRF) approach can reduce computational time by eliminating the need to regenerate the mesh at each time-step to accommodate the moving geometry. A static local reference zone encompassing the impeller is created and the impact of the impeller movement is modeled via a momentum source. However, the MRF approach is not a predictive simulation because the impeller speed must be given by the User. A new simulation approach was introduced that coupled the FSI and MRF approach. Like in the FSI approach, the total moment of the impeller was calculated based on the resultant force acting over the impeller surface. This calculation…
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Investigation of an Advanced Combustion System for Stoichiometric Diesel to Reduce Soot Emissions

Southwest Research Institute-Avery Chase, Jason Miwa, Zainal Abidin, Khanh Cung
Published 2019-01-15 by SAE International in United States
Diesel engines are facing increased competition from gasoline engines in the light-duty and small non-road segments, primarily due to the high relative cost of emissions control systems for lean-burn diesel engines. Advancements in gasoline engine technology have decreased the operating cost advantage of diesels and the relatively high initial-cost disadvantage is now too large to sustain a strong business position. SwRI has focused several years of research efforts toward enabling diesel engine combustion systems to operate at stoichiometric conditions, which allows the application of a low-cost three-way catalyst emission control system which has been well developed for gasoline spark-ignited engines. One of the main barriers of this combustion concept is the result of high smoke emissions from poor fuel/air mixing. The current study focuses on improving the combustion system by investigating different fuel/air mixing strategies that enhance fuel spray - piston bowl interaction while simultaneously optimizing the fuel injection system. Computational Fluid Dynamics (CFD) simulations were carried out in conjunction with engine testing to evaluate different piston bowl designs as well as injector nozzle designs…
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Optimization of Heavy Duty Diesel Engine Lubricant and Coolant Pumps for Parasitic Loss Reduction

Southwest Research Institute-Daniel Christopher Bitsis, Jason Miwa
Published 2018-04-03 by SAE International in United States
As fuel economy becomes increasingly important in all markets, complete engine system optimization is required to meet future standards. In many applications, it is difficult to realize the optimum coolant or lubricant pump without first evaluating different sets of engine hardware and iterating on the flow and pressure requirements. For this study, a Heavy Duty Diesel (HDD) engine was run in a dynamometer test cell with full variability of the production coolant and lubricant pumps. Two test stands were developed to allow the engine coolant and lubricant pumps to be fully mapped during engine operation. The pumps were removed from the engine and powered by electric motors with inline torque meters. Each fluid circuit was instrumented with volume flow meters and pressure measurements at multiple locations. After development of the pump stands, research efforts were focused on hardware changes to reduce coolant and lubricant flow requirements of the HDD engine. As engine hardware changes were made to reduce coolant and lubricant requirements, the fuel economy benefit was immediately realized. Several hardware sets are discussed along…
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Effect of Micro-Hole Nozzle on Diesel Spray and Combustion

Southwest Research Institute-Khanh Cung, Daniel Christopher Bitsis, Thomas Briggs, Vickey Kalaskar, Zainal Abidin, Bansal Shah, Jason Miwa
Published 2018-04-03 by SAE International in United States
The influence of nozzle geometry on spray and combustion of diesel continues to be a topic of great research interest. One area of promise, injector nozzles with micro-holes (i.e. down to 30 μm), still need further investigation. Reduction of nozzle orifice diameter and increased fuel injection pressure typically promotes air entrainment near-nozzle during start of injection. This leads to better premixing and consequently leaner combustion, hence lowering the formation of soot. Advances in numerical simulation have made it possible to study the effect of different nozzle diameters on the spray and combustion in great detail. In this study, a baseline model was developed for investigating the spray and combustion of diesel fuel at the Spray A condition (nozzle diameter of 90 μm) from the Engine Combustion Network (ECN) community. Upon validation of parameters such as spray penetration, lift-off length, and ignition delay the baseline simulation was extended to study different nozzle orifice diameters. All simulations were performed using a constant-volume combustion chamber (CVCC) geometry with similar ambient conditions of pressure (60 bar) and temperature (900 K). It was shown…
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Efficiency and Emissions Characteristics of Partially Premixed Dual-Fuel Combustion by Co-Direct Injection of NG and Diesel Fuel (DI2) - Part 2

Southwest Research Institute-Gary D. Neely, Radu Florea, Jason Miwa, Zainal Abidin
Published 2017-03-28 by SAE International in United States
The CO2 advantage coupled with the low NOX and PM potential of natural gas (NG) makes it well-suited for meeting future greenhouse gas (GHG) and NOX regulations for on-road medium and heavy-duty engines. However, because NG is mostly methane, reduced combustion efficiency associated with traditional NG fueling strategies can result in significant levels of methane emissions which offset the CO2 advantage due to reduced efficiency and the high global warming potential of methane. To address this issue, the unique co-direct injection capability of the Westport HPDI fuel system was leveraged to obtain a partially-premixed fuel charge by injecting NG during the compression stroke followed by diesel injection for ignition timing control. This combustion strategy, referred to as DI2, was found to improve thermal and combustion efficiencies over fumigated dual-fuel combustion modes. In addition, DI2 provided significant thermal efficiency improvement over the baseline diffusion-controlled combustion strategy (HPDI) where NG injection occurs after diesel injection. The DI2 combustion process was analyzed using 3D-CFD and indicated that additional CH4 reductions from the crevice region may be possible by…
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Evaluation of Cold Start Technologies on a 3L Diesel Engine

Southwest Research Institute-Jason Miwa, Darius Mehta, Chad Koci
Published 2016-04-05 by SAE International in United States
Increasingly stringent emissions regulations require that modern diesel aftertreatment systems must warm up and begin controlling emissions shortly after startup. While several new aftertreatment technologies have been introduced that focus on lowering the aftertreatment activation temperature, the engine system still needs to provide thermal energy to the exhaust for cold start. A study was conducted to evaluate several engine technologies that focus on improving the thermal energy that the engine system provides to the aftertreatment system while minimizing the impact on fuel economy and emissions. Studies were conducted on a modern common rail 3L diesel engine with a custom dual loop EGR system. The engine was calibrated for low engine-out NOx using various combustion strategies depending on the speed/load operating condition. The technologies that showed strong potential during this evaluation include a turbine bypass system, early exhaust valve opening, cylinder deactivation, and delayed engine starting. The performance of these technologies was compared using an engine test cell which was programmed to simulate the first portion of the FTP-75 test cycle.
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Efficiency and Emissions Characteristics of Partially Premixed Dual-Fuel Combustion by Co-Direct Injection of NG and Diesel Fuel (DI2)

Southwest Research Institute-Radu Florea, Gary D. Neely, Zainal Abidin, Jason Miwa
Published 2016-04-05 by SAE International in United States
For the US market, an abundant supply of natural gas (NG) coupled with recent green-house gas (GHG) regulations have spurred renewed interest in dual-fuel combustion regimes. This paper explores the potential of co-direct injection to improve the efficiency and reduce the methane emissions versus equivalent fumigated dual-fuel combustion systems. Using the Westport HPDI engine as the experimental test platform, the paper reports the results obtained using both diffusion controlled (HPDI) combustion strategy as well as a partially-premixed combustion strategy (DI2). The DI2 combustion strategy shows good promise, as it has been found to improve the engine efficiency by over two brake thermal efficiency (BTE) points (% fuel energy) compared to the diffusion controlled combustion strategy (HPDI) while at the same time reducing the engine-out methane emissions by 75% compared to an equivalent fumigated dual-fuel combustion system. Details of the DI2 combustion process were obtained using 3D-CFD simulations and suggest further improvements of the dual-fuel combustion system are possible.
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Demonstration of a Novel, Off Road, Diesel Combustion Concept

Southwest Research Institute-Daniel Christopher Bitsis, Charles Roberts, Jason Miwa, Christopher Chadwell, Sankar Rengarajan
Published 2016-04-05 by SAE International in United States
There are numerous off-road diesel engine applications. In some applications there is more focus on metrics such as initial cost, packaging and transient response and less emphasis on fuel economy. In this paper a combustion concept is presented that may be well suited to these applications. The novel combustion concept operates in two distinct operation modes: lean operation at light engine loads and stoichiometric operation at intermediate and high engine loads. One advantage to the two mode approach is the ability to simplify the aftertreatment and reduce cost. The simplified aftertreatment system utilizes a non-catalyzed diesel particulate filter (DPF) and a relatively small lean NOx trap (LNT). Under stoichiometric operation the LNT has the ability to act as a three way catalyst (TWC) for excellent control of hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx). The two-mode diesel combustion concept was implemented on a 6.8L medium duty diesel engine and several iterations of the combustion system were evaluated for smoke response and combustion efficiency. The engine was then evaluated over the Non Road Transient…
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