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| Jan Ridders' Simple LTD Stirling Engine - craynerd build log |
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| NickG:
Chris, The top displacer cover on yours looks thick too - is that to drawing? I'm not quite sure how this will affect it's operation - it may retain more heat than a thin cover would, will the heat transfer as well though the thick base as it would a thin one? or if your top plate is thick, will you need the base to be thick too? I don't know the answers to these questions but what I'm trying to say is, I'd leave the base as it is until you've tried running it, as it could affect something. I'd also try your existing power piston after sealing it up. If that doesn't work, try a new power piston first before altering the base - much easier to make than a new base! nearly there :thumbup: Nick |
| raynerd:
Hi Nick, just read your message. I`m trying to stick to the plans as much as possible as I believe these are tricky to run as they are so I want to work as near as possible to a known method and dimensions. The plans call for a 1mm thick base and the top I think 5mm, although my base is 6mm, I`ve now thinned it down in the centre to just shy of 1mm so the clear perspex displacer now sits on a small shoulder and the bottom disk is then recessed to 1mm thin base. I`m guessing the thicker edges could actually effect it so I may remove them if I have a problem. I`m sure someone will correct me but my understanding is that this engines, LTD - low temp differential, work due to the difference in temperature between the top and bottom plate. In theory, the base size shouldn`t matter but of course if it is thicker it`ll take longer to heat up, especially if I`m hoping for it run of a low temperature source - like the palm of my hand :lol: .. I wish! A thinner base will heat up quicker and having a thicker top plate would mean it will heat up slower and therefore maintaining a great temperature difference for a longer period and greater running time. I`m guessing putting grooves in the top plate would give a greater area for heat loss and would make the engine perform better. I am going to run with this graphite piston. I`ve thinned the top plate last night and also made the holder for the flywheel. Pictures to come later... Chris |
| mklotz:
Chris, You may know this already but be aware that you can run your engine from a 'cold source' just as easily as with a heat source. At exhibitions I baffle the onlookers by setting my LTD on a cold pack (or saucer of ice cubes) and letting it run off the heat available from the air or sunshine hitting the top plate when out of doors. After the spectators have seen this I plop the engine onto a cup of coffee and it begins to run in the opposite direction. Spectators generally know nothing of physics so they're astounded. Incidentally, take the engine to your local bar/pub and do what I described above. The trick is usually worth a free pint or two. :D |
| GordTopps:
Good tip! :D :) Gordy |
| kwackers:
I use ice lollies too. People just don't get it - the idea an engine can run off 'cold' causes some of them great difficulty. They simply don't consider room temperature to be 'hot'. In real terms though 273 deg K is almost the same as 300 deg K... |
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