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Reusing loss heat

Posted: Mon Aug 11, 2008 1:20 am
by trgl317
Hey, I'm trying to build a Stirling engine, and I've ran into some
problem that I hope someone more experienced can give me some advice
on. In building a Stirling engine, inevitably the cold cylinder wall
would eventually get hotter. I'm looking for a solution to this
problem that would hopefully raised the efficiency of my project. What
would be a good way to reroute the heat back to the original power
source? Since I'm still in the planning stage, I'm still quite unclear
as to how much heat will eventually migrate through despite the insulator.
Thanks for your time.

Response to Reusing loss heat

Posted: Mon Aug 11, 2008 12:00 pm
by johnemack
Hello John,

You ask >how much heat will eventually migrate throughdespite the insulator reroute the heat back to the original power
source?< Heat will flow only from hot to cold! However, some waste heat can be recovered by using it to pre-heat the burner air before recuperating from the flue.

There is much scope for ingenuity in maximizing efficiency (but I still haven’t done my sums).

Another John.

Response to Reusing loss heat

Posted: Mon Sep 01, 2008 2:56 pm
by longboy4
..........John, You seem to be introducing complications and conditions to your model that just may not exist. Also not sure of your type of model you are planning. Assuming a traditional Stirling model heated with an open flame. If your model is a horizontal configuration,it is true that the heated air pathway to the power cylinder eventually warms up the components around that cylinder. Also true is that will not prevent your motor from running for extended periods. Solutions to the migrating heat through the body of a model are relativly strait forward. Some are 1) Radiator up! Air cooled.....more fins, larger diameter fins. Liquid cooled.....greater capacity water jacket around the displacer cyl. Or 2) Heat sink it into suppression. The block you bolt the displacer cyl. to......thicker, broader, larger. Mill in some grooves to displace that waste heat as it builds up. 3) using a non-conductive air pathway, vinyl or silicon tubing conecting the displacer & power cyl...........If your motor is a verticle configuration such as a Stirling fan motor, then John Mack's answer comes into play. After all, your whole model is sitting above a alcohol flame and thin wall, non-conducting, insulating materials are needed to deflect, reflect and disperse all this heat rising into the body of the model. I'm not hip to this waste heat reroute. Don't know why this is neccesary. Are you building a competition engine, or as just a running novelty of your own handywork? Don't get lost in the math.............up and running beats efficiency anytime! Dave.