I got 30 out of 29. I eliminated question 21 because all their answers are wrong. Diesel engines get better mileage because they use more compression, so get a longer adiabatic expansion and extract mode of the energy in the fuel. The actual energy in most fossil hydrocarbon fuels is nearly equivalent.
Why is this in SED?
Clifford Heath.
In other words "a longer adiabatic expansion" - a bigger temperature change during expansion. More of the heat energy is extracted.
When turbo diesels suddenly became *driveable*, I wondered what the break-through was. Now we know. All you have to do is to dodge emissions testing :/
Fair point.
Clifford Heath.
"It's under the hood of every car, truck and SUV, but how many people really know how one works? Do you know a spark plug from a fuel injector?
Take the quiz.
I got 26 out of 30
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29
overthought one
On Monday, January 11, 2016 at 7:24:18 PM UTC-8, Clifford Heath wrote: ...
Diesel fuel does contain about 10% more energy per gallon
So they are somewhat correct although I also did not like the accuracy of there answers.
I tried some of there other quizzes and there were a number of errors there as well.
kevin
30/30. Piece 'o cake.
** A Diesel engine has a higher combustion temperature and cooler exhaust which makes the thermal efficiency higher than a petrol engine.
But there are so many disadvantages that it is only comparatively recently that highly developed diesel engines have become competitive in automobiles.
** If you compare by equal weights, but fuel is sold by volume and that gives denser fuels the advantage - about 12% in the case of diesel v petrol..... Phil
30/30. Pretty lame questions.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
This has nothing whatever to do with stroke length, and everything to do with compression ratio. Higher compression ratio (static compression as you say) determines the temperature drop during expansion, which translates directly to lower exhaust temperature (more heat energy has been extracted).
(snip other correct but irrelevant stuff)
** Diesel engines do not necessarily have a longer stroke than similar capacity petrol types, so your point fails.
The mechanical ( ie static) compression of an engine is simply the ratio of swept volume to head volume - so just making the head smaller increases the ratio for the same capacity.
There is a lot going on inside a 4 stroke engine and most of the usual, neat assumptions fall down as the rpms increase - so designers get creative.
Capacity produces torque and rpms transform torque into power - but to get lots of both at the same time is fighting against nature and one heck of a trick.
.... Phil
I got 30 out of 30. But mainly because I just happened to have had a 2-stroke auxiliary generator that started detonating, so I already knew about that.
joe
30, but had to think about the spud gun, that's a different thing here.
Steam engines may return, at least partially in the form of the six stroke engine. Suck squeeze bang whoosh squirt puff...
Cheers
-- Syd
Fun. It would be hard to get the steam bit to have the same RPM characteris tics as the gasoline bit.
The biggest problem with steam engines for vehicles is the heat exchanger o n the cold side. It's bound to be seriously large, but the alternative is t o run an open cycle, which wastes a lot of heat.
Cheers
Phil Hobbs
One design (Crower) I saw used open cycle - yes it wastes heat, but does away with the normal cooling system. The article said you need to carry about as much water as fuel, but fuel efficiency is up by 40%. AIUI materials are a problem.
Cheers
-- Syd
28/30... I got the one on diesel wrong.. And I don't think of a four cycle engine as compact.
anyway...
George H.
One question looked like it had two right answers. Inline, V, flat, and rotary are all legitimate engine types. Why not rotary engines?
they asked for the most common, afaict since mazda stopped there aren't any cars today with rotary engines
-Lasse
On Tue, 12 Jan 2016 06:40:30 -0800 (PST), Lasse Langwadt Christensen Gave us:
That is mass production. In the racing aftermarket realm, however:
And then new designs meant to get around the inherent design flaw of the wankel topology, namely the rotor apex seals.
I've noticed Americans think you're a big nerd for knowing anything about technical stuff. A big time loser nerd.
Sometimes I mention to young people in a bar that I work with electronics and they'll mutter "neeeerd" under their breath. :)
It's kind of like how Americans will see you working on a math problem and fall all over themselves to tell you that they're terrible at math and no good.
"Hello! I see you reading a book there. Did I mention I'm illiterate?"
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That's the one I missed.
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