Subject: [FlyRotary] Re: water cooled matrix in oil pan

 

`The problem with this is that the oil is essentially stagnant in the pan'

 

Al, this is only 'cause you haven't looked inside when its running - there's

an oil pump driving this stuff round the engine all the time, it just starts

and finishes at the bottom of the oil pan.  The flow rate will be the same

as anywhere else on the system that you would choose to oil/air cooler.  Its

true that the `dwell time' in the oil pan will be longer as this is your

reservoir but this is a good thing.

 

The key word is “essentially”; and it’s the velocity that counts. The oil moves in the channels of the oil cooler at about 20 ft/min; enough to give you good convective heat transfer coefficient. If you assume that the oil entered the pan at one end and traversed across it might be moving about ½ ft/min (the actual case would be likely be less because it is moving more from top to bottom). Convective heat transfer would be “essentially” zero, and you would have to rely on conduction; but, of course, the thermal conductivity of oil is not very good, so . . .

 

It could be done; but it is not simple.  A large pan volume with cooled plates and narrow oil channels could do the job.  Sounds a bit expensive and maybe heavy; so a nice compact, effective oil/air heat exchanger sounds pretty good.

 

And BTW, folks. A good balance of theory and experiment is where it’s at.  Let’ not forget that without the theory and engineering; there wouldn’t be a rotary engine.

 

Al