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A New Lease On Internal Combustion
Somnus suggests we check out the latest issue of MIT's Technology Review, where researchers describe how they can dramatically boost engine output and efficiency by preventing pre-ignition, or "knock." How they do it: "Both turbocharging and direct injection are preexisting technologies, and neither looks particularly impressive... by combining them, and augmenting them with a novel way to use a small amount of ethanol, Cohn and his colleagues have created a design that they believe could triple the power of a test engine."
This should be a lot more accurate than the original summary.
Blah blah sig blah blah blah irony blah blah
Yes. Note that I don't actually believe the claim about tripling power, at least not with a whole lot of *very heavy* reinforcement of the block and heads.
For example: (Note: Numbers strictly pulled out of ass.)
2.4l conventional engine: 150 hp, 30 mpg
2.4l Super-Mega-Monster-Gas-TDI-Ethanol engine: 450 hp, 12.5 mpg
Your engine is 25% more efficient per hp and is generating 3x as much power.
Of course, the real application they have in mind is to create reinforced motorcycle-size engines that can power sedans, or small car motors that can power SUVs. If your 2.0l engine can create 360 hp, big torque, and get 17-18 mpg, you've reinvented a turbodiesel, except that your engine is (even with reinforcements) way smaller and lighter.
"People in the tuning industry have been controlling "knock" in various ways for a long time."
Exactly. This sounds a lot like water injection, which has been around forever and does increase mpg by about 10% in turbo cars and allows lower octane fuel.
Here's what's going to kill the technology from TFA:
"Ethanol would be stored in its own tank or compartment and would be introduced by a separate direct-injection system. The ethanol would have to be replenished only once every few months, roughly as often as the oil is changed. A vehicle that used this approach would operate around 25 percent more efficiently than a vehicle with a conventional engine."
This is exactly like water-injection and it's why we don't see water-injection in vehicles. No one wants to have a separate tank that we need to remember to fill-up, and the 10% increase provided by water just isn't enough. This is the same story except it's ethanol, not as easy to find as water, and it's 25% better mpg instead of 10%.
We will never see a production ethanol injection vehicle. Vaporware with a capital V
my karma will be here long after I'm gone
From TFA (and this goes for the reply above mine as well as the parent):
"Similar approaches, some of which used water to cool the cylinder, had been tried before. But the combination of direct injection and ethanol, Cohn says, had much more dramatic results."
Show me someone in the tuning industry using directly injected ethanol along with a turbocharger and regular gas. I've never heard of this approach.
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
I was thinking the same thing when I started reading the article. A quick search at any of the major car enthusiast websites will lead you to dozens of threads on direct injection and forced induction (turbocharging). This isn't news. There are already direct injection, turboed factory motors out there. The 2007 Saturn Sky Red Line, for example, is powered by a 2.0-liter direct injection turbo engine. You may have heard of another auto manufacturer using this same technology in it's diesel engines... VW's TDI (Turbo Direct Injection).
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The "new" part comes where they are using ethanol direct injection. It's a new twist on an old idea. See also water-methanol injection:
http://en.wikipedia.org/wiki/Water_injection_(eng
Sure, it's not anything evolutionary. And the article might read like 1st Grade literature for anyone who is familiar with cars and tuning... but it's still interesting stuff.
You're correct about all that, but the insanely high pressure is probably as much about getting the fuel into the chamber as it is about proper atomization. See, in a gasoline engine the fuel is [typically] drawn in with the intake air charge, although they are using direct injection sometimes as well. But in a diesel the ignition timing is controlled by injection timing. Diesels are typically over 17:1 compression - my Mercedes (currently defunct) is 22:1, PLUS an 11 PSI turbocharger. So you need considerable pressure just to get the fuel into the chamber. My Mercedes is old-school, it uses indirect injection (think CVCC, it's got a prechamber) but it also uses a mechanical injection pump that basically consists of a cam that runs five cylinder-type pumps (think hydraulics) and is driven by a connection to the crankshaft.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
The '07 MINI Cooper'S has a 4 cylinder 1.6 liter direct-injected twin-turbocharged engine - and since most fuel in the US now contains 10% ethanol, I'd say the "experimental" technology these guys are pushing is already out there in at least one production car. The problem with knocking has been nailed a bazillion years ago - just about all modern cars have an anti-knock sensor that can richen the mixture if it detects signs of knocking - but with high octane gasoline - it only very rarely has to actually do that - so the "problem" of knocking isn't really there. The only time the MINI actually does something like that is when the dumb user filled the thing with regular low-octane gas instead of 'the good stuff'.
Add to that that the MINI has goodies like electric oil, power steering and water pumps that can actually be turned off (rather than merely bypassed) when not needed - so the engine reaches it's most efficient temperature faster and you aren't burning fuel circulating fluids that don't need to be circulated yet. It has computer controlled inlet and exhaust valves - so the timing is infinitely variable - and can be varied separately for each cylinder. For short bursts of accelleration, the car has an 'overboost' feature from the turbo - which won't help you much for prolonged hard accelleration - but is great for a rapid burst of speed for overtaking, blasting out of a corner (FUN!) or blowing away those bloody ugly Scion xB's at traffic lights (a personal mission of mine, I might add).
www.sjbaker.org
the beauty of a diesel is it runs on any oil, used cooking oil, cod liver oil, diesel fuel oil, motor oil. Properly setup itl'l run on used motor oil, used transmission fluid, used any oil.
I'm intrigued to imagine what they could do if this ethanol based charge cooling works out. I'm already forced to put 15% ethanol in my Audi V8 (sadly NOT an RS4), living in NYC, but if this works out maybe I can support the farmers AND have a powerful car for the weekends (I commute on the subway).
The '07 MINI Cooper'S has a 4 cylinder 1.6 liter direct-injected twin-turbocharged engine - and since most fuel in the US now contains 10% ethanol, I'd say the "experimental" technology these guys are pushing is already out there in at least one production car
As the article notes, direct injection has been around for a while (since the '50s). Turbochargers are older than that. The idea here uses direct injection in a novel way.
. . . just about all modern cars have an anti-knock sensor that can richen the mixture if it detects signs of knocking - but with high octane gasoline - it only very rarely has to actually do that - so the "problem" of knocking isn't really there.
The problem isn't stopping current engines from knocking. The problem is to increase compression ratios or boost of an engine without introducing knocking. Increasing the amount of gas in the mixture only makes your fuel efficiency worse.
The key to this new idea is that the ethanol is injected separately from the regular gas (specifically, during the compression phase). Naturally, you'll need a separate tank of ethanol, which the article claims would need to be replenished about as often as a oil change.
As we know from thermodynamics, matter going through a phase change from liquid to vapor will suck away a lot energy. Ethanol has the nice quality that it will go through a phase change at a lower temperature compared to water.
Thermodynamics also tells us that as pressure increases, so does temperature. In a normal engine, the piston will compress the fuel/air mixture, thus increasing the temperature of the mixture. If the temperature gets too high, the mixture will ignite on its own. This is more likely if your engine has too high of a compression ratio or you're using some kind of boost system (turbo or superchargers). This is why cars with turbos often have intercoolers.
What they're doing here is increasing the compression ratio and/or adding a turbo. You can choose to slap on an intercooler if you wish. As the piston goes through the compression stroke, the fuel/air mixture gets hotter as before, but then some ethanol is injected, which vaporizes, thus cooling the mixture. The mixture is then ignited by a spark plug normally. Brilliant.
Not a typewriter
Preignition is when the fuel/air charge ignites at the point of lowest compression, and then the engine has to compress this hot, expanded gas. This is how holes get burned in pistons. Knock is detonation, where the fuel/air charge does not burn in a controlled flame front, i.e. it suddenly detonates. It requires that timing advance be backed down a bit.
There are only 10 kinds of people in this world... those who understand binary and those who don't
Other people have different things to say about Cobasys:
And this, which killed the electric RAV4:There's plenty more, just perform the search suggested at the first link.
It appears likely that the advances in Li-ion and carbon-backed lead-acid will make it far more difficult to keep the next round of batteries out of vehicles. Regardless, the delay in availability of mass-market PHEV's and EV's has meant many billions or tens of billions of dollars in additional revenue for the oil companies and oil exporting nations. (The current administration shares responsibility for e.g. terminating the Partnership for a New Generation of Vehicles, which would have delivered 80-MPG sedans about.... now.)
The take-home lesson? Don't believe everything you read.
Sustainability and energy independence essay