Comparison Suggests Gasoline-Powered MUSIC Engine Could Exceed Diesel Efficiency
21 December 2008
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| Comparison of the BTE of 2.0L MUSIC and 2.4L diesel at different load points. Click to enlarge. |
A recent comparison of a 2.0-liter, four-cylinder implementation of the Merritt Unthrottled Spark Ignition Combustion (MUSIC) engine, initially developed at Coventry University (earlier post) with a 2.4-liter diesel engine suggested that the gasoline-fueled MUSIC engine could attain a higher brake thermal efficiency than the diesel across a wide range of engine loads.
The MUSIC performance data was taken from testing in April 2008 at the end of an Energy Saving Trust funded project. The diesel data was provided, in confidence, by a “reputable” engine R&D company, according to MUSI Engines Ltd. The BMEP conditions at which the diesel results were taken only approximate to those of MUSIC’s, and MUSI said that it did not have details on the exact construction of this diesel or on the parasitic loads which were included in the evaluation of its BTE.
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| Comparison of 2.0L MUSIC and 2.4L diesel. Click to enlarge. |
MUSIC is an un-throttled, high thermal efficiency, lean-burn, spark ignition system that uses an indirect combustion chamber to produce charge stratification by means of controlled air management. The four-cylinder prototype tested is essentially a new cylinder head and its associated combustion system mounted on a Ford Duratec crankcase.
Unlike competing technologies, the MUSIC system does not require any new supporting technology. Apart from the cylinder head, the 4 cylinder prototype engine uses currently available production components throughout albeit in the case of the injectors to new specifications.
The MUSIC engine tested was driving its own GDI fuel pump and oil pump, but was not driving its water pump, alternator or fan. Dr. Dan Merritt, the inventor of the MUSIC engine, suggested that the advantage in BTE of the MUSIC over the diesel could be enabled by the following:
Below BMEP loads of some 7 bar, all the fuel burnt in MUSIC is contained and is fully burnt only within the external combustion chamber which exposes a much smaller surface area to the flame, some 40% compared with the direct diesel engine.
MUSIC combustion rates can be much faster than diesel. The gasoline is vaporized when ignited and the stratified primary zone is stoichiometric when ignited by a spark. Faster combustion avoids burning during the expansion stroke which is penalizing for thermal efficiency.
The MUSIC engine tested has two valves per cylinder, a lower friction load and lower fuel pump parasitic load.
MUSIC operates with simple solenoid GDI (gasoline direct injection) injectors, at moderate fuel line pressure and without pulsing to meet lower loads and speeds. While earlier studies, reported in the Coventry University seminar on MUSIC in February 2008, suggested that MUSIC may also need to pulse the delivery of its injectors to meet lower demands even though it uses relatively low fuel line pressure (below 200 bar), the developers now conclude that pulsing will not be necessary. An economy injector will be able to meet loads up to 7 bar with a power injector topping up with short durations from 5 bar onwards. At higher BMEP demands the power injector will control load by increasing injection duration and advancing the injection starts with increasing engine speeds and loads.
Details of MUSIC in comparison with competing technologies will be covered at the Symposium on International Automotive Technology (SIAT) in India, 21-23 January 2009. SIAT is organized biennially by the Automotive Research Association Of India (ARAI). SIAT is graded as an SAE conference and technical papers published in SIAT will find place in the SAE database.
Why spend money researching these four cylinder ICE's with relatively insignificant gains in performance, when electic powered vehicles are the wave of the future? ...ejj...
Posted by: ejj | 21 December 2008 at 08:53 AM
ejj:
Very light, small, highly efficient (50%??) ICE may be required to drive on-board generators for extended range PHEVs for the next 10 to 20 years.
Practical and affordable pure BEVs will not be a reality before baterries' energy density has reached 500+ Wh/Kg.and the price has dropped significantly below $300/Kwh.
That may take 10 to 20 years unless the industrial nations joint their effort and support an all azimuth development and mass production program soon.
Posted by: HarveyD | 21 December 2008 at 09:59 AM
"electic powered vehicles are the wave of the future? ...ejj..."
Unless built by companies I hate.
Posted by: Reel$$ | 21 December 2008 at 10:38 AM
Reel$$:
To love or to hate a company is often a question of propaganda.
Posted by: HarveyD | 21 December 2008 at 10:43 AM
What I like with these guys is that they have been regularly communicating milestones of achievement, proof of concept, simulation, real tests (contrary to scamers like Scuderi or EESTOR) . I was skeptical at first that they could get signifcant improvment because of the simplicity of their concept (but often the simplest concept is the most efficient in mechanic). Their result are quite impressive indeed.
Eji, even if we were spending all our resources in electric car right now I don't think we would have more than 10% electric car around in 2030. We have to accept as a fact of life that the ICE would stay as the mainstream for quite some time to come so in that sense it could be more important to improve ICE than battery in the fisrt place. It would be big mistake to work only at making the world as we wish it should be and ignore to make it just a bit better than it is.
Posted by: Treehugger | 21 December 2008 at 11:06 AM
The George Santayana quote, "Those who cannot learn from history are doomed to repeat it" echoes throughout the energy industry.
Ever since the 70's, oil prices rise, then suddenly fall - crushing oil replacement technologies prior to their viable commercial implementation - yet no one wakes up. Does anyone seriously believe OPEC will not, directly or indirectly, again double oil prices as soon as traffic can bare it?
America, in some manner, must stabilize its gasoline prices at a known, roughly $3/gallon rate. This will allow electric and plug-in hybrid vehicles (BYD F3DM etc.) to replace the ICE personal car. This will also enhance bio-fuel development for long haul trucking and airline industries - where batteries are not a presently viable option.
Hopefully, bio-fuels will also yield critical industry petrochemical replacements. If not, significantly reduced demand will allow remaining world oil to be purchased at reasonable prices.
America, the world, cannot pay $100(limitless?) per barrel of oil that OPEC admits only costs them a dollar something to pump to the surface. We have the technology. It's only a question of will and honest leadership.
Posted by: kelly | 21 December 2008 at 11:35 AM
Harvey D is right. It is highly unlikely that pure battery powered vehicle would be mainstream any time soon or maybe never will be. Many says ICE is deadend becuase it's been there for 100 years but we begin to see sudden high efficiency ICE delopement everywhere...so Its evident that there are still significant improvement to be made in ICE at very reasonable cost. Remember NiMH batteries are mass produced for cars right now but still at very high price so there's doubt that lithium Ion batteries would be cheaper...
Posted by: Sean Lee | 21 December 2008 at 01:27 PM
kelly:
Oil quickly going form $10/barrel to $145/barrel certainly had a snowball effect on the current economic turmoils. Current high cost wars, tax reductions and very large budget deficits also helped.
Too many $ trillions changed hands too quickly and had to be recycled thus creating an economic oversized bubble, promoting easy credits, oversized house, car and credit cards loans etc to absorb all the money coming back.
Pumping more $$$ B into the current economic bubble may make it grow even bigger and burst even louder.
Doing nothing or too little or the wrong thing will lead to a quick long lasting recession (already there in most countries) and possible depression and further price deflation.
Stabilizing oil and other energy prices may require more unliked regulations and/or unpopular variable equilizing oil and alternate fuel taxes.
What a challenge for the new Administration and the industrial nations.
One thing is certain, it will take ingenuosity, leadership, international coordination and time to fix all that has failed. Four years may not be enough. We may be in it for a full decade.
Posted by: HarveyD | 21 December 2008 at 01:58 PM
-"Practical and affordable pure BEVs will not be a reality before baterries' energy density has reached 500+ Wh/Kg.and the price has dropped significantly below $300/Kwh"
I believe that $/wh of capacity isn't as important as $/cycle. If a battery costs $1000/kwh and is good for 2000 cycles it is cheaper than a battery that costs $500/kwh and is good for 500 cycles, no?
If a standardized format is agreed upon for batteries and they have very long cycle lives they become attractive for long term financing.
-"Remember NiMH batteries are mass produced for cars right now but still at very high price so there's doubt that lithium Ion batteries would be cheaper..."
These packs are currently favored for reasons of safety. If they were cheaper they would still be present in consumer electronics. Li-ion is actually cheaper than NiMh on a per watt basis now.
I am a little suspicious of those diesel efficiency numbers: something in the low 40s should have shown up. The only modern LDV turbo diesel that I can think of is an Audi 2.4L V6.
Still, I am very impressed by the MUSIC concept. It is simple and could (should) be widely deployed without substantial re-tooling. The seperate combustion chamber allows for some unique approaches to thermal management: ceramic coatings could be applied readily to further improve TE and reduce the cooling load.
Tell me what you think of this:
~2.0L I4
Natural Gas specific
~13:1 compression ratio
MUSIC cylinder head
Oribital air assited NG DI
Artemis IVT
That could be our "bridge" vehicle until battery research gets farther along.
Posted by: GreenPlease | 21 December 2008 at 08:31 PM
GreenPlease said:
"These packs are currently favored for reasons of safety. If they were cheaper they would still be present in consumer electronics. Li-ion is actually cheaper than NiMh on a per watt basis now."
This is ABSOLUTELY 100% FALSE.
Li-ion is used in consumer electronics because it offers more power & greater energy density which consumers are willing to pay extra for over NiMH because the batteries are small so the perceived costs are low. We purchase small quantities of batteries (less than 100K packs/year) compared to consumer electronics companies but our cost for NiMH is still about 50% less than the cost for basic Cobalt based Li-ion cells.
If you tell a consumer they can buy the NiMH battery for $40 and get 3 hours of battery life or they can purchase the Li-ion battery for $80 and get 5 hours of life they almost always go for Li-ion (in my particular industry).
Posted by: Patrick | 21 December 2008 at 09:03 PM
"The BMEP conditions at which the diesel results were taken only approximate to those of MUSIC’s, and MUSI said that it did not have details on the exact construction of this diesel or on the parasitic loads which were included in the evaluation of its BTE."
This seems highly suspect. Of course everybody is all for increased efficiency, but why even compare to a diesel engine in the first place?...what am I missing?
Posted by: Andrew Blair | 21 December 2008 at 10:05 PM
If MUSIC really does work, it could have very dramatic effects on the automobile industry. Since a MUSIC engine uses gasoline as a fuel, it means we can use well-proven emission control systems for the engine to easily meet ULEV-II/Tier 2 Bin 5 level compliance, unlike the almost Rube Goldberg-like emission controls needed for diesel engines to meet the same emissions goal. This could mean Europe will have to worry less about the increased NOx and diesel particulate emissions of diesel engines.
Posted by: RaymondC | 22 December 2008 at 12:49 PM
As others have noted, the lack of knowledge of what engine it is being compared to calls the claims somewhat into question - for example, a VW TDI 4-cylinder diesel engine has a best-efficiency point in the 42% range, which is the same as what MUSIC claims for theirs, and the numbers for the diesel seem low by modern standards. But still, it's very good for a spark-ignition engine.
BUT.
Where is the information on HC and NOx emissions, which are the traditional bugaboos of practically all lean-burn spark-ignition concepts.
The current-production VW TDI diesel engine is approximately 42% efficient at its best-efficiency point AND it meets US EPA Tier 2 bin 5, albeit with complex exhaust aftertreatment. A lean-burn spark-ignition concept, if it operates consistently with other such systems, would require almost equally comparable de-NOx catalysts.
It is possible to operate current-production gasoline-direct-injection (GDI) engines in lean-burn mode, and there is a big efficiency benefit, but it isn't done in production due to NOx emission standards. I don't see why this one would be any different, and having seen a drawing of the shape of the combustion chamber, I daresay it has more surface area for heat loss (read: potential efficiency loss) than a "traditional" 4-valve pentroof with GDI does ...
Posted by: Brian P | 24 December 2008 at 03:19 PM
I should address something in the post above mine. "Traditional well-proven emission control systems" are designed for stoichiometric combustion. If fed a lean exhaust stream, which would be the case with either a GDI engine running in lean-burn or a MUSIC engine running in lean-burn, they can't reduce the NOx. Lean-burn engines, whether diesel or spark-ignition, need de-NOx catalysts to meet current emission standards.
Love the concept ... now demonstrate the NOx emissions compliance. I'm afraid that therein lies the rub.
Posted by: Brian P | 24 December 2008 at 03:23 PM
"Why spend money researching these four cylinder ICE's with relatively insignificant gains in performance, when electic powered vehicles are the wave of the future? ...ejj..."
Uh ... because electric vehicles have less than 25% of the range of a gasoline vehicle and take forever to recharge. And technically they are coal powered cars, just using electricity as the middle man. That is far dirtier than a gasoline engine with catalyst.
Posted by: shifterguy | 29 December 2008 at 01:13 PM