Search found 10 matches

by ElecTech
Sat Jan 25, 2014 9:47 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hot Cold Ratios
Replies: 17
Views: 9998

Re: Hot Cold Ratios

Hi Ian, The support post is out of 1/2" plate and there are (2) 1/2"ODx1/4"ID ball bearings carrying the crank loads. No noticeable seesaw effect. Time will tell if I need to change out the tie-rods. The ambient temp saturation atop the fireplace insert may expedite that requirement. Crankdwg.JPG
by ElecTech
Fri Jan 24, 2014 7:44 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hot Cold Ratios
Replies: 17
Views: 9998

Re: Hot Cold Ratios

Here are the finished spec's I ended up with. I planned to use the glass cylinder and found 32mm test tubes I ordered were .005-.006 out of round. I didn't want to order a long stick of boro. The replacement cylinder and lower section are titanium. Graphite piston, Ball bearings in the conrods and d...
by ElecTech
Fri Jan 24, 2014 7:35 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hot Cold Ratios
Replies: 17
Views: 9998

Re: Hot Cold Ratios

Success! I know this is an old thread, but I wanted to update those that offered their input. Here are the pictures of the finished project. I did find out that the brass rod has a high thermal conductivity, transferring heat to the top plate and lost differential temp. The fan would quit after abou...
by ElecTech
Thu May 30, 2013 5:19 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hot Cold Ratios
Replies: 17
Views: 9998

Re: Hot Cold Ratios

Bumpkin, Our stove is connected to the duct work and blows out around the insert. I run it just under 500degF and a portion of the radient heat is probably distributed through the cold air return (running the summer fan) once the main area is warm. I'd find it worthless if my stove would not radiat ...
by ElecTech
Wed May 29, 2013 9:42 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hot Cold Ratios
Replies: 17
Views: 9998

Re: Hot Cold Ratios

Hi Hopper, I am focusing on engine driven fans which do not appear to follow the basic volume ratio rules of thumb directly. These would still be considered Gamma engines although just set on a hot surface. Burner engines have a much broader temp differetial and much higher heat. I think I can concl...
by ElecTech
Tue May 28, 2013 3:27 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hot Cold Ratios
Replies: 17
Views: 9998

Re: Hot Cold Ratios

Ouch! That hurt! :laugh: I've been using the coversions for years. It's just not native. It's like speaking another language where I have to convert it to comprehend, calculate - then unconvert it to comprehend again... Well, mm aren't so bad. Working in (new to me) scientific exponential portions o...
by ElecTech
Sun May 26, 2013 11:45 am
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hot Cold Ratios
Replies: 17
Views: 9998

Re: Hot Cold Ratios

Vamoose, Ian, You are correct about the missing finer details and precisley why I put in the caveat about incomplete data for my crude calculator. As to dead space, it appear to be a minimal aspect on these proven engine types I have looked into being so short coupled. No long run pipes, tubes or pa...
by ElecTech
Sat May 25, 2013 7:36 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hot Cold Ratios
Replies: 17
Views: 9998

Re: Hot Cold Ratios

Ian, Using the 3:1 hot length:dia ratio I have used your numbers in my calculator with a few estimates. Here are the results. You can correct the estimates if need be. My calculator puts the displacer length=(stroke -.03") shorter than the hot end length and the displacer diameter .03 smaller than t...
by ElecTech
Fri May 24, 2013 5:48 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hot Cold Ratios
Replies: 17
Views: 9998

Re: Hot Cold Ratios

Hello Ian, Thanks for responding. I've seen that picture in my research of the somewhat rare stirling fan projects. I'm so glad to have you chime in. Nice work BTW! Yes, I have read Stirlings ratio of 3:1 for the hot end. By my estimation provided the data of proven concepts seem to suggest the prim...
by ElecTech
Thu May 23, 2013 6:28 pm
Forum: Stirling and "Hot Air" Engine Forum
Topic: Hot Cold Ratios
Replies: 17
Views: 9998

Hot Cold Ratios

New to the forum here. I've built the Mizer LTD stirling and would like to build a Stirling stove fan as my next project. I have several CAD drawing versions and I'm about ready to begin cutting metal. I'd like to start off discussing probably the most frequent mysterious burning question as to hot ...