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Low Temperature Combustion

[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]

Tsinghua team devises in-cycle control method for diesel LTC using detection of Start of Combustion

November 25, 2014

Low temperature combustion (LTC) refers to a broad range of in-cylinder combustion strategies for the reduction of NOx emissions from diesel combustion; NOx is formed primarily by a thermal mechanism, which production rates increasing exponentially with temperature. LTC strategies reduce combustion temperatures by the dilution of the in-cylinder combustible mixtures, either with excess charge gas to create more fuel-lean mixtures, or with moderate to high levels of EGR.

However, challenges remain in diesel low temperature combustion implementation due to combustion inconsistency or instability. To address this, a team from Tsinghua University has devised an in-cycle combustion feedback control method based on the detection of the Start of Combustion (SOC) in diesel LTC. A paper describing their method is published in the journal Applied Energy.

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DOE to award more than $55M to 31 projects for plug-in and efficient vehicle technologies; Delphi receives $10M to further GDCI

August 14, 2014

The US Department of Energy (DOE) is awarding more than $55 million to 31 new projects to accelerate research and development of vehicle technologies that will improve fuel efficiency and reduce costs under a program-wide funding opportunity announced in January. (DE-FOA-0000991, earlier post.) These new projects are aimed at meeting the goals and objectives of the President’s EV Everywhere Grand Challenge (19 projects), as well as improvements in other vehicle technologies such as powertrains, fuel, tires and auxiliary systems (12 projects).

The largest single award ($10 million) goes to Delphi Automotive Systems to further the development of its Gasoline Direct-Injection Compression Ignition (GDCI) low-temperature combustion technology (earlier post) that provides high thermal efficiency with low NOx and PM emissions. The largest number of awards (9) in a single area of interest goes to developing beyond Li-ion battery technologies.

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Space station droplet combustion experiments reveal cool-burning flames; potential to lead to better engines

July 30, 2014

Isolated droplet combustion experiments performed on the International Space Station (ISS) by a team of international researchers have revealed a new type of cool-burning flames. The long durations of microgravity provided in the ISS enable the measurement of droplet and flame histories over an unprecedented range of conditions, enabling the discovery. The researchers detailed their findings in an open access paper in the journal Microgravity Science and Technology

A better understanding of the cool flames’ chemistry might help improve internal combustion engines in cars, for example by developing homogenous-charge compression ignition, which could potentially lead to engines that burn fuel at cooler temperatures, emitting fewer pollutants such as soot and nitric oxide and NOx, while still being efficient.

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Caterpillar and Argonne’s VERIFI undertake cooperative virtual engine design, control project; first VERIFI CRADA

July 03, 2014

Low-temperature combustion regimes show great efficiency and emissions potential, but they present optimization and control challenges that must be addressed before they enter the engine mainstream.

Caterpillar Inc. has entered into a Cooperative Research and Development Agreement (CRADA) with Argonne National Laboratory and its recently formed Virtual Engine Research Institute and Fuels Initiative (VERIFI), where experts are developing new engine combustion models that incorporate accurate descriptions of two-phase flows, chemistry, transport phenomena and device geometries to provide predictive simulations of engine and fuel performance.

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A pathway to gasoline compressed ignition using naphtha fuels; higher efficiency, lower cost

May 02, 2014

A new study by Dr. Gautam Kalghatgi and his colleagues at Saudi Aramco provides further support a pathway for significant improvements in the efficiency of a gasoline engine (i.e., spark ignited, SI) by running it in compression ignition mode with naphtha fuels. (Earlier post.) This latest work, presented at SAE 2014 World Congress, shows that moving to higher compression ratios (CR) and lower fuel cetane numbers (DCN) from an SI base engine offers a better trade-off than increasing DCN with a lower CR. In other words, using only cetane to improve CI fuel consumption is less beneficial than relying on a low cetane fuel and higher compression ratio.

Past work done by Kalghatgi and his team, as well as by Prof. Bengt Johansson at Lund University and others, has demonstrated that using low-octane gasoline in diesel engines has the potential to achieve very high efficiency while reducing the cost of diesel engines by lowering injection pressures and requiring less expensive exhaust aftertreatment. Broadly, this approach is termed Gasoline Compression Ignition (GCI).

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Oak Ridge researchers pursuing in-cylinder reforming for control of advanced combustion

April 21, 2014

Researchers at Oak Ridge National Laboratory are pursuing investigations into the use of a non-catalytic in-cylinder reforming process—i.e., the conversion of liquid hydrocarbon fuel to a hydrogen- and CO-rich syngas—potentially for controlling combustion phasing in homogeneous charge compression ignition (HCCI) and other forms of advanced combustion.

When fuel is injected during negative valve overlap (NVO) in O2-deficient conditions, a portion of the fuel is reformed to products containing H2 and CO. In a paper presented at the recent SAE 2014 World Congress, the ORNL team and colleague from Sandia National Laboratories reported on the chemistry of an NVO in-cylinder reforming process as experimentally determined from a single-cylinder engine. The Oak Ridge team plans to pursue the in-cylinder reforming technique in a multi-cylinder configuration in which one of the engine cylinders would act as the reformer, “essentially breathing in reverse compared to the other cylinders (breathing in from the exhaust manifold and exhausting into the intake system).”

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Promising Delphi 1st-gen Gasoline Direct Injection Compression Ignition engine meeting ultra fuel efficient program targets

April 17, 2014

Researchers at Delphi Powertrain, in collaboration with colleagues at Hyundai Motor, the University of Wisconsin-Madison, and Wisconsin Engine Research Consultants (WERC), have developed a first-generation multi-cylinder Gasoline Direct Injection Compression Ignition (GDCI) engine, based on several years of extensive simulations and single-cylinder engine tests. (Earlier post, earlier post.)

In a presentation at the SAE 2014 High Efficiency IC Engine Symposium and then in a paper given at SAE 2014 World Congress, Mark Sellnau, Engineering Manager, Delphi Advanced Powertrain, reported that Brake Specific Fuel Consumption for the 1.8L GDCI engine was significantly better than advanced production spark-ignited gasoline engines, and comparable to very efficient hybrid vehicle engines at their best efficiency conditions (214 g/kWh). Compared to new diesel engines, the Delphi team found that BSFC for GDCI at light loads was comparable or better, and at high loads was about 5% higher.

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Brunel engineers optimizing CAI combustion in 2-stroke camless gasoline DI engine

February 10, 2014

Brunel
Operating range of 2-stroke CAI fueled with gasoline, E10 and E85. Zhang et al. (2013a) Click to enlarge.

Researchers at Brunel University in the UK, led by Professor Hua Zhao, Head of Mechanical Engineering and Director, Centre for Advanced Powertrain and Fuels (CAPF), are investigating optimizing the performance of controlled autoignition (CAI) combustion in a four-valve camless gasoline direct injection engine running in a two-stroke cycle. Most recently, this has entailed an exploration of boosting strategies, as described in a new paper published in the International Journal of Engine Research, as well as an exploration of the effects of ethanol blends.

Controlled autoignition (e.g., homogeneous charge compression ignition, HCCI) combustion processes offer the promise of simultaneously reducing fuel consumption and NOx emissions. Accordingly, the processes have been extensively researched over the last decade and adopted on prototype gasoline engines (e.g., GM’s ongoing work, earlier post).

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Nissan reveals Frontier Diesel Runner with 2.8L Cummins turbo diesel; leveraging ATLAS engine program

February 06, 2014

Frontier_Diesel_Runner_01
Nissan Frontier Diesel Runner Powered by Cummins. Click to enlarge.

At the Chicago Auto Show, Nissan debuted a concept diesel-powered mid-size pickup: the Frontier Diesel Runner Powered by Cummins. Based on a Frontier Desert Runner 4x2 model, was created to gauge the market reaction to a Nissan mid-size pickup with a diesel engine and plot a potential future direction for the Frontier.

The Frontier Diesel Runner arrives six months after the announcement of a partnership with Cummins Inc. to provide a 5.0-liter turbo diesel V8 in the next-generation Titan full-size pickup, which will arrive in calendar year 2015. (Earlier post.)

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Study finds butanol-gasoline blends effective to control soot from CI engines under Low Temperature Combustion

January 31, 2014

Butanol
(Left) Thermal efficiency and (right) soot from different gasoline-butanol blends at different EGR rates. Yang et al. Click to enlarge.

A study by a team at Tianjin University found that the addition of n-butanol to gasoline for use in a compression ignition engine (CI) under Low Temperature Combustion (LTC) conditions has a significant effect on soot reduction. The peak soot value of a 30% butanol blend (B30) was 85% lower than that of pure gasoline; the EGR rate that corresponds to the peak value of soot is also decreased with the higher n-butanol fraction. Their study is published in the journal Fuel.

Partially Premixed Combustion involving the injection of gasoline fuel into CI engines is being explored by other researchers as a means to reducing simultaneously NOxand soot emissions. High octane fuels such as gasoline are preferred for high-efficiency and clean combustion at high engine loads, the Tianjin researchers note.

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U Wisc.-Ford team develops more realistic multi-component surrogate diesel models for modeling of low temperature combustion

December 07, 2013

A team from the Engine Research Center at the University of Wisconsin-Madison, Ford Motor, and Ford Forschungszentrum Aachen have developed new multi-component surrogate models for three different diesel fuels, and then examined their fidelity in capturing the characteristics of a diesel engine operated under various conditions, including conventional and low-temperature combustion (LTC) modes.

Fuel and EGR effects were also explored in the two different combustion modes using the developed surrogate models. In a paper published in the ACS journal Energy & Fuels, they reported that the results showed that the combustion trends in conventional combustion are less affected by fuel or EGR changes, while LTC conditions exhibit a much higher sensitivity, thus demanding more realistic fuel models precisely to describe advanced combustion modes.

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