Crazy car motor idea

[xelasnave]

Its raining..
So we take a 6 cylinder motor and for three of them instead of injecting fuel we inject water on every upstrock.
Would the heat we lose be converted this way.
Would the heat of the cylinder next to a water in jection cylinder cause meaningful steam (expansion method) and power.
Alex

[raymo]

Hi Alex, Even at idling r.p.m. the exhaust valve[s] couldn't let the water
escape from the cylinder fast enough to avoid hydraulicing, which in turn
would stop the engine almost instantaneously, and bend the connecting rod[s] like a banana.This all being because, unlike gas, you can't compress water.
The idea sounds promising, but even with mods to allow the water to get into and out of the cylinder quickly enough to avoid the aforementioned problem,
it would not work because the amount of water in the cylinder would be far
too great to allow the heat transfer during the very short time that the water is in the cylinder. You might, with experimentation, get warm to hot water.
Another possible barrier would be the huge temperature gradients across the different parts of the engine might cause cracks in the block or cyl.head[s].
raymo

[xelasnave]

Thanks for your well considered reply.
I am injecting a very small amount of water. I cant recall what the expansion is from water to steam but a little voice remembers 3000 times, but there will be a number for the volume of water, but I expect it to be very small 10,20 mls may do it.
Or maybe inject water at bottom of stroke and go for traditional steam engine.
I have a gut feeling it could be made work.
I must find if 3000 times is a ywhere near the mark. Also even with small amounts of water you would go thru a bit.
A mate just offerred me a boat I have wanted for 10 years I ha e to get my mind off it.
Alex

[xelasnave]

No bottom stoke wont do it, for at first not obvious to me, reasons

[raymo]

O.K. Alex, I misunderstood quite what it was that you were proposing, so we
have to start again.
Firstly, to stop a water cooled engine from overheating and self
destructing, each cylinder is surrounded by water which carries away the heat
[to the radiator]. This means that the very high temps generated by the
operating cylinder will not reach the wall of the adjacent cylinder. It will
only receive heat from the water[90-105c], which is nowhere near high enough to flash the water into steam in the very brief time that the water
would be in contact with the cylinder wall.
It is conceivable that it could be made to work if the water was preheated
to close to boiling point. Once the engine was up to full operating temp, you
could utilise its heat to achieve this, but you would need a separate heating
device for initial start up.
You are quite right, the volume of water is increased by 3000 when it
becomes steam.
raymo

[xelasnave]

Excellent with the problems identified we can start on a proto type.
Thanks for thinking upon this next gift to mankind.
Alex

[raymo]

You're welcome.
raymo

[jenchris (Jennifer)]

What are you proposing to do with the steam generated?
How do you propose to stop water getting into the sump?
Wouldn't energy be easier to draw from the exhaust?
Or, using a heat pump from the radiator?
I remember an experiment where 10%water was mixed with fuel using ultrasonics and burnt in the engine. This improved engine efficiency somewhat, but created corrosion problems in the exhaust.
I can't see energy being absorbed from alternate cylinders on a 6 cyl engine being effective enough to warrant the research. The delta on steel is actually quite poor.
And I guess making the engine from silver would be less than cost effective even if you could make it robust enough. Why not go for a titanium Geneva wheel engine?
You might get some higher figures from something like that.
The Maxwell cycle works quite well, and can be used with anything combustible.

[raymo]

I'm assuming [perhaps wrongly] that Alex is doing some sort of thought experiment, and I'm happy to try and help. It gives me something to do
in my dotage.
raymo

[GTB_an_Owl (Geoff)]

i can remember talk about "dripping" water into the carby to improve mileage around the 60's

geoff

[raymo]

Water injection is beneficial, cools the fuel/air mix in the cylinder, increasing its density. Some jetliners use[d] it. One of the Commodores from the late
70s had an optional water injection system.
raymo

[BC]

Perhaps a bit off topic, but I used to run a large single SU carby on my EH Holden with water injection to moderate combustion temperatures and used to get 30 MPG (9.4L/100km). A big change from the 17 MPG when I bought the car.

Bruce

[deanm (Dean)]

The Harrier jump jet engine used water-methanol injection to increase take-off/landing thrust: link

And automotive applications are everywhere

Dean

[xelasnave]

Water injection with fuel in my view, having used it on my first car, delivered more power and better full economy. I believe it was used in some Spitfire aircraft, termed "boost".

I thought it may be possible to convert some of the heat wasted in a motor by extracting it via steam working half of the pistons.

The idea turns upon one question.
Would there be enough heat to change a small amount of water into steam.

No doubt there would be wear and corrosion issues just the sort of problems engineers love to overcome.
I dont think water in the sump would be encounterred. Once the water is injected if it turns to steam will it push the piston down and exhaust the steam in the same manner as exhausting burnt fuel.

I am not married to the idea and interested to hear why it could work and what the engineers would need to consider now that lubrication issues, and perhaps higher opperating temps need to be addressed.

Such a motor may demand an absence of water jacketing surrounding the steam cylinders for example. The water may come from the radiator so it is preheatedand able to vaporise better (hinted at earlier) so then we need the radiator to also be a supply source needing constant top up.

But it all turns on the vaporisation via the heat of the motor and the "fuel ecconomy" you get for the price of carrying a tank of water in addition to a tank of fuel.

Alex

[xelasnave]

Fitting the injector in place of the spark plug would be a mod that would help so as to make water delivery more efficient.... These cylinders would need only an exhaust valve.

Who knows how to fill out a pattent application we could make billions when we iron out the problems.

[AndrewJ]

Gday Alex
I suspect one big problem you would have to overcome is that the std IC engine portion would have to run at a speed far higher than the reciprocating steam engine could work at, esp if the steam has to be created by flash boiling in situ.

Andrew

[raymo]

There would have to be a valve of some kind open when the piston is on its
way down, sucking in either a gas or a liquid in sufficient quantity to avoid
a vacuum forming. The piston could not descend against a vacuum.
raymo

[raymo]

That wouldn't be an insurmountable problem Andrew. If the water is under fairly high pressure, and at a temp of >400 degrees it can be made to flash pretty much instantaneously. Some steam recip engines operate at a bit over 1000rpm, and using superheated water could operate much faster than that.
IMHO, at this stage of thinking about it, each solved problem would lead to
another; for instance, superheated water is VERY dangerous to work with,
and requires engineering and components of the highest quality, in turn making the project very expensive.
raymo

[AndrewJ]

Gday Raymo

If the water is under fairly high pressure, and at a temp of >400 degrees

Agreed, but in this case the energy to heat the water and also raise its pressure has to come from the engine itself.
At this scale, the pump required would probably use more energy than you got back, let alone when you factor in all the other thermal losses along the way. Be fun to crunch the numbers reqd, based on only having tiny pistons.

Some steam recip engines operate at a bit over 1000rpm

Yep, but i dont know of any designs that would do that based on using an existing cylinder in a std IC engine block.


Andrew

[AstralTraveller (David)]

The cooling water of an engine is at about 100C. Use this to heat a liquid with boiling point <100C and use the 'steam' to drive a turbine to generate electricity which can be stored or used as required. It's much more complex than the original idea but I imagine it could work. However, if no manufacturer is working on this system it does tend to suggest that the gain is not worth the effort.