...use oil instead of water?
No internal corrosion, no anti-freeze needed and I would think you still get effective heat transfer.
or am I missing something?
--
|
Cost?
Oh cynical ole me!
|
|
Some motor bikes do. R1200GS Oilhead anyone ?
|
My late GSX 750 had an oil cooler, but that was to cool the oil as opposed to using oil to cool the engine.
--
|
|
|
|
Water is simply more efficient at transferring heat.
|
Oil may be effective but water is much more effective as a heat transfer medium.
I think the thermal conductivity of oil is about 4 times less than water.
The specific heat capcity of oil is about 2 times less than water. (2.0 KJ/kg Degree compared with 4.2 KJ/kg per Degree for water).
Oil is also slightly less dense than water.
I'm not sure what modifications this would require in practice but:
The lower heat capacity of oil might require the oil coolants volume flow rate to be doubled.
The higher viscosity of oil would create require more energy to circulate.
However antifreeze has a lower specific heat capacity than pure water so the heat capacity of the actual 'coolant' will be around 3.5 KJ/kg Degree
Interesting question though. I look foward to Number Crunchers proper analysis soon....
|
|
Hmm, what about transformer oil, this is a light oil designed for heat dissipation and transfer.
|
www.midel.com/English/properties.html
Specific heat at 20°C J/kg K 1880 1510 1860
Thermal conductivity at 20°C W/m K 0.144 0.151 (@ 50°C) 0.126
Kinematic viscosity at 20°C mm2/s 70 50 (@ 25°C) 22
Kinematic viscosity at 100°C mm2/s 5.25 15 2.6
How does this compare to water/coolant?
|
|
|
Hmm what about transformer oil this is a light oil designed for heat dissipation and transfer.
used because it has more electrical resistance, and more resistant to galvanic corrosion than water.
------------------------------
TourVanMan TM < Ex RF >
|
|
|
|
>>Interesting question though. I look foward to Number Crunchers proper analysis soon....
I don't have much to add. (Which will come as a relief to many!!!)
;-)
Except that we've probably all seen alloy sumps with cooling fins on the outside. In reality, the fins would be far better on the inside, because the greatest thermal resistance is between the oil and the alloy - not between the alloy and the air.
In practice, you can use oil for cooling, but you need to keep it moving fast. So there's typically a decent oil flow rate through turbos and being squirted underneath the pistons of turbo-diesel engines.
Number_Cruncher
|
If you used oil as a coolant you wouldn't be able to detect a head gasket leak by the presence of oil in the coolant. I think that's the reason. ;-)
--
L\'escargot.
|
|
Suzuki persevered with oil cooled bike engines for many years, GSXRs though to the late 90's and Bandits until this year however they cannot meet the thermal efficiency of a water cooled engine, a particular issue when it comes to emmisions.
|
|
|
|
|
Water is simply more efficient at transferring heat.
And it's not so messy if it expands (with heating) such that it overflows.
--
L\'escargot.
|
|
|
Water is simply more efficient at transferring heat.
And it's easier to get it topped up if it runs short. In a real emergency you could even pee in it ~ if there were enough of you to make up the shortfall.
--
L\'escargot.
|
Been there, done that, got the tee-shirt. Driving three mates back from somewhere where they'd all been drinking pints. I'd drawn the short straw that time. I'd done something to the car and hadn't tightened a hose clip, and didn't notice until the temp gauge started climbing. Unlit road, but I had a torch. I managed to make them hold it until I'd found the problem. I think only one of them managed to give himself a minor burn (difficult, balancing on the front bumper, aiming into a small hole when you've had a skinful). It gave us enough liquid until we found some water.
I do remember the overpowering stench when I drained it to re-fill with anti-freeze solution.
|
Make sure you depressurise and remove the expansion cap BEFORE you unzip the flies.......
------------------------------
TourVanMan TM < Ex RF >
|
A bloke asks a serious question and you just take the ........
Air cooled engines are oil cooled, the oil transfering the heat to the finned crankcases to air
|
Air cooled engines are oil cooled the oil transfering the heat to the finned crankcases to air
So you could say that water cooled engines are oil cooled the oil transfering the heat to the water via the water jacket and/or heat exchanger.
The definition of oil cooled is that oil is pumped through a rad.
|
So you could say that water cooled engines are oil cooled the oil transfering theheat to the water via the water jacket and/or heat exchanger. The definition of oil cooled is that oil is pumped through a rad.
VWs air cooled engines have both an oil pump and an oil cooler radiator inside the fan shroud. An Oxford oil cooled arc welder has no radiator or pump
Read any decent article on aircooled VW or Porsche engines and it will state that the oil transfers the heat and helps to cool the engines components
|
|
|
|
I once lost all water out of my old van due to a hose blowing,i fixed the hose and then started cramming snow into the radiator cap.
You wouldnt believe how much snow this takes, so i gave up and drove another 45 miles to my destination with no water in the system ,but it was a well below freezing day (no global warming in the 70"s you see :-) )
Testement to the old mk 1 escort overhead valve engines going on for nearly ever i think.
I ended up having to put a new headgasket on it and having to get a tow start of the rac. but she ran again for a long time afterwards. once done.
|
|
|
|
|
|
|
didnt the norton featherbed frame ( motorcycle) incorporate an oil cooler thru said frame?
|
A guy called Granville Bradshaw designed an oil-cooled engine for motorcycles more than 80 years ago (IIRC). It was used by a number of manufacturers including DOT (which I believe is still in business, after a fashion, but not using the same engine!).
It did become known as the 'oil boiler' though...
|
|
|
|
A good deal of engine cooling comes from the oil as is anyway, even in the most basic enclosed crancase IC engine. Even more if a oil cooler is fitted
But for out and out efficency aroun combustion chambers/cylinders etc water is hard to beat
|
|
back in the days before antifreeze my grandfather used diesel in cooling systems but only in the winter ,I seem to remember him saying something about it boiling of too quick in the summer higher temperatures ,it was quite a long time ago but its funny how some things stick in your mind
|
|
|
|
