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Originally Posted by mort
It appears almost identically here: Internal Combustion Engine Fundamentals by John Heywood
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I have that one as well ... and another good book.
Quote:
Originally Posted by mort
Another book I like is Engine Testing Theory and Practice by Anthony Martyr, Michael Alexander Plint
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Agree ...
I have the 3rd edition in my collection as well... another good one.
Quote:
Originally Posted by mort
Additionally, if you consider an engine at idle, throttled of course, the bhp is zero so all the heat in the fuel must come out in the coolant and exhaust (plus radiation...) At idle the coolant heat is infinity times the shaft power.
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Quote:
Originally Posted by mort
What I expect to happen in a throttled engine, well above idle,
So I would expect heat put into the coolant to be much less than 1/4 of coolant heat at WOT at that rpm.
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For the Coolant system to go from infinity% of Shaft power down to 25% of shaft power ... it transition between them in terms of % of shaft power ... it might not be a perfectly smooth transition along those points but ... the 175% you found incredible therefore must exist between those points ... less than infinity% and more than 25% ... so does 250% and 70% ... etc.... etc...
So we see an offset between the RPM you would expect this condition to happen at and the reported RPM ... which leads to a question of what would cause that kind of offset in that context ... I suspect part of it ( not sure what % ) of that is due to the lean burn operation ... many engines running at lean burn have significantly different heat production than those not running at lean burn and lean burn also significantly reduces the produced shaft power per engine cycle ... it changes the ratio between heat and shaft power as you going into lean burn.
Quote:
Originally Posted by mort
So here is a graph I made up of what I think a constant rpm vs throttle heat balance would look like.
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Even if it worked exactly as you depict ... and that chart were 100% perfect match to a real test engine ... we can find on that chart of yours points where the coolant system exceeds 100% of the shaft power... lower and lower RPMs until as you pointed out yourself the gap between coolant system going to infinity% and shaft going to zero... as long as that relationship exists it is only a question of where does it exceed 100% ... where does it reach 175% , etc.
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Originally Posted by Blacktree
One thing to note about electrolysis is that when you re-combine the H2 and O2 molecules, you get exactly the same amount of energy back that was put in, to crack the water molecules in the first place.
As they say in physics "there's no free lunch".
And that is the problem with on-board electrolysis machines. You can't get more energy out of the water than you put into it. So you're not gaining anything. And since the machines you're using to crack the water molecules, and then re-combine the Hydrogen with the Oxygen, are less than 100% efficient, there's actually a net loss of energy.
To get a net gain of energy (for the car, anyway), you need to electrolyze the water off-board (for example, at home), and then put the gas in the car. But this will still be a net loss of energy (in total). It's just that you're shifting the energy loss to someplace other than the car. While your gasoline bill might go down a bit, your electric bill will go up.
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While I agree with a lot of what you wrote ... I will make one point of clarification ... there are endothermic conditions of electrolysis ... where a small % of the energy chemically stored in the H2 & O2 came from heat absorbed from the area ... this heat energy does not have to be 'paid for' by the electricity in the electrolysis ... so yes the energy came out that went in , but some of that 'go in' energy doesn't have to come from the electricity the user is paying for ... unfortunately it is too small of a % to compensate for ( as you already wrote ) all the other steps that are less than 100% efficient... and the final result is still getting out less than one put in... and even if the other steps could somehow be improved enough to get close ... it would just move the question to what one was using as a heat source for that 'free to me' energy input... it can't be something you ever have to pay for or it is not longer 'free' and that greatly limits the already very limited endothermic potential that is still to small to offset the other less than 100% efficient steps.