Question Heatpipes and vapour chambers: could they be used to cool internal combustion engines?

[80251]

Title says it all. I remember I built a 4 stroke thumper XR650r (big bore piston and polished heads) and the machine shop suggested extended fins on the cylinder and cylinder head, but aside from an oil cooler that's all they could suggest to cool the engine. Could heatpipes and/or vapour chambers be adapted or scaled up to be used in air cooled engines?

 

[CountMike]

Title says it all. I remember I built a 4 stroke thumper XR650r (big bore piston and polished heads) and the machine shop suggested extended fins on the cylinder and cylinder head, but aside from an oil cooler that's all they could suggest to cool the engine. Could heatpipes and/or vapour chambers be adapted or scaled up to be used in air cooled engines?

They are made with spongy ceramic layer bonded to inside walls of pipes or chamber and act as a wick to condense low dew point of vapors of liquid pipes are partially filled with. That would never survive temperatures and vibrations of motorcycle or car engines. Liquid cooling is much better.

 

[geofelt]

The shop suggestion for larger fins is probably best.
Heat pipes move heat from one source to a radiator. Where might that radiator be?
If heat is an issue on the bike, is it while idling, or under full speed?
An aux fan to move air while idling could help.
An air intake cowl might direct more air when moving to the cooling fins.

 

[kanewolf]

Title says it all. I remember I built a 4 stroke thumper XR650r (big bore piston and polished heads) and the machine shop suggested extended fins on the cylinder and cylinder head, but aside from an oil cooler that's all they could suggest to cool the engine. Could heatpipes and/or vapour chambers be adapted or scaled up to be used in air cooled engines?

Just like in compute, liquid cooling is simpler and cheaper, at the extreme.

 

[geofelt]

Back in the 1940's, Hitler demanded a peoples car with low weight and cheap.
The liquid cooled engines at the time could not do the job.
Hence the air cooled VW was developed, Lighter and cheaper than cars at the time.
With today's pc cooling, I think the dividing line between air and liquid is around the 280 aio being comparable to a top air cooler and 360 or larger where more cooling is needed

 

[Eximo]

Heat pipes are used in some automotive components, but quite rarely, and pretty much always with electronics. The main reason is cost, so typically the casing is used as a heatsink for heat generating components.

The working fluid in heatpipes is designed for that 20-80C range or so, typically just water. Engines are generally too warm for that, so the heat pipes would always be saturated and you might as well just use copper directly.

Adding surface area certainly won't hurt an air cooled engine, but I think the other suggestions are worth looking into. Forced air, cowling, or adding significant mass to the fins sound better to me.

Doing some sort of water jacket, adding a pump and radiator is also an idea.

Some quick searching does reveal the existence of high temperature heat pipe solutions. But these seem to be for high temperature industrial processes and power generation. Well above the temperatures an engine would normally experience.

 

[Paperdoc]

Yeah, the temperature / pressure / filling fluid thing is a BIG factor in heat pipe use. The heat pipe merely moves heat from the high-temp location to a point where a heat exchanger system can cool the medium. In a computer CPU cooler the medium inside the pipe is water with a bit of corrosion protection additive, and it ALWAYS operates at temperatures between 0 and 100 C, so that water is ALWAYS as liquid with some vapour ("steam") and at a pressure LESS than 15 psi. Further, at the point of heat removal inside the heat exchanger, the vapour is cooled enough to condense back to liquid and drain down again by gravity. To make a similar system to work over a range of temperatures from, say, -40 C (for REALLY cold ending in cold places) to 150 C (300 F) would require finding a really odd fluid! (Water actually IS a really odd fluid!)

For what you did with that bike, larger fins (longer, with good spacing for high air flow through) similar to the existing attached heat exchanger is the much better way to increase heat removal capacity. I'm sure that a whole circulating liquid-filled cooling system could not be done - that would require complete redesign of the entire engine block and heads.

 

[80251]

I wasn't at all entertaining the idea of using heatpipes and/or vapour chambers for my motorcycle, I was just curious as to whether anyone, anywhere had done any research into trying to scale up heatpipes and vapour chambers to work w/any type of air-cooled engine (maybe even much smaller engines, like those used in remote control car racing), not mine specifically.