Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

MIT's pint-sized engine promises high efficiency, low cost

27.10.2006
--Ethanol empowers the little engine that could

MIT researchers are developing a half-sized gasoline engine that performs like its full-sized cousin but offers fuel efficiency approaching that of today's hybrid engine system--at a far lower cost. The key? Carefully controlled injection of ethanol, an increasingly common biofuel, directly into the engine's cylinders when there's a hill to be climbed or a car to be passed.

These small engines could be on the market within five years, and consumers should find them appealing: By spending about an extra $1,000 and adding a couple of gallons of ethanol every few months, they will have an engine that can go as much as 30 percent farther on a gallon of fuel than an ordinary engine. Moreover, the little engine provides high performance without the use of high-octane gasoline.

Given the short fuel-savings payback time--three to four years at present U.S. gasoline prices--the researchers believe that their "ethanol-boosted" turbo engine has real potential for widespread adoption. The impact on U.S. oil consumption could be substantial. For example, if all of today's cars had the new engine, current U.S. gasoline consumption of 140 billion gallons per year would drop by more than 30 billion gallons.

"There's a tremendous need to find low-cost, practical ways to make engines more efficient and clean and to find cost-effective ways to use more biofuels in place of oil," said Daniel R. Cohn, senior research scientist in the Laboratory for Energy and the Environment and the Plasma Science and Fusion Center (PSFC).

Cohn, John B. Heywood, the Sun Jae Professor of Mechanical Engineering and director of the Sloan Automotive Laboratory, and Leslie Bromberg, a principal researcher at the PSFC, have an engine concept that promises to achieve those goals.

For decades, efforts to improve the efficiency of the conventional spark-ignition (SI) gasoline engine have been stymied by a barrier known as the "knock limit": Changes that would have made the engine far more efficient would have caused knock--spontaneous combustion that makes a metallic clanging noise and can damage the engine. Now, using sophisticated computer simulations, the MIT team has found a way to use ethanol to suppress spontaneous combustion and essentially remove the knock limit.

When the engine is working hard and knock is likely, a small amount of ethanol is directly injected into the hot combustion chamber, where it quickly vaporizes, cooling the fuel and air and making spontaneous combustion much less likely. According to a simulation developed by Bromberg, with ethanol injection the engine won't knock even when the pressure inside the cylinder is three times higher than that in a conventional SI engine. Engine tests by collaborators at Ford Motor Company produced results consistent with the model's predictions.

With knock essentially eliminated, the researchers could incorporate into their engine two operating techniques that help make today's diesel engines so efficient, but without causing the high emissions levels of diesels. First, the engine is highly turbocharged. In other words, the incoming air is compressed so that more air and fuel can fit inside the cylinder. The result: An engine of a given size can produce more power.

Second, the engine can be designed with a higher compression ratio (the ratio of the volume of the combustion chamber after compression to the volume before). The burning gases expand more in each cycle, getting more energy out of a given amount of fuel.

The combined changes could increase the power of a given-sized engine by more than a factor of two. But rather than seeking higher vehicle performance--the trend in recent decades--the researchers shrank their engine to half the size. Using well-established computer models, they determined that their small, turbocharged, high-compression-ratio engine will provide the same peak power as the full-scale SI version but will be 20 to 30 percent more fuel efficient.

But designing an efficient engine isn't enough. "To actually affect oil consumption, we need to have people want to buy our engine," said Cohn, "so our work also emphasizes keeping down the added cost and minimizing any inconvenience to the driver."

The ethanol-boosted engine could provide efficiency gains comparable to those of today's hybrid engine system for less extra investment--about $1,000 as opposed to $3,000 to $5,000. The engine should use less than five gallons of ethanol for every 100 gallons of gasoline, so drivers would need to fill their ethanol tank only every one to three months. And the ethanol could be E85, the ethanol/gasoline mixture now being pushed by federal legislation.

Through their startup company, Ethanol Boosting Systems LLC, the researchers are working with their Ford collaborators on testing and developing this new concept. If all goes as expected, within five years vehicles with the new engine could be on the road, using an alternative fuel to replace a bit of gasoline and make more efficient use of the rest.

Written by Nancy Stauffer, MIT Laboratory for Energy and the Environment

Elizabeth A. Thomson | MIT News Office
Further information:
http://www.mit.edu

More articles from Power and Electrical Engineering:

nachricht Filter may be a match for fracking water
26.09.2017 | Swansea University

nachricht Fraunhofer ISE Pushes World Record for Multicrystalline Silicon Solar Cells to 22.3 Percent
25.09.2017 | Fraunhofer-Institut für Solare Energiesysteme ISE

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The fastest light-driven current source

Controlling electronic current is essential to modern electronics, as data and signals are transferred by streams of electrons which are controlled at high speed. Demands on transmission speeds are also increasing as technology develops. Scientists from the Chair of Laser Physics and the Chair of Applied Physics at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) have succeeded in switching on a current with a desired direction in graphene using a single laser pulse within a femtosecond ¬¬ – a femtosecond corresponds to the millionth part of a billionth of a second. This is more than a thousand times faster compared to the most efficient transistors today.

Graphene is up to the job

Im Focus: LaserTAB: More efficient and precise contacts thanks to human-robot collaboration

At the productronica trade fair in Munich this November, the Fraunhofer Institute for Laser Technology ILT will be presenting Laser-Based Tape-Automated Bonding, LaserTAB for short. The experts from Aachen will be demonstrating how new battery cells and power electronics can be micro-welded more efficiently and precisely than ever before thanks to new optics and robot support.

Fraunhofer ILT from Aachen relies on a clever combination of robotics and a laser scanner with new optics as well as process monitoring, which it has developed...

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Nerves control the body’s bacterial community

26.09.2017 | Life Sciences

Four elements make 2-D optical platform

26.09.2017 | Physics and Astronomy

Goodbye, login. Hello, heart scan

26.09.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>