Search found 3286 matches
- Fri Apr 26, 2024 1:38 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 41
- Views: 365
Re: Isothermal Heat Transfer
But by doing work and loosing energy and getting cold, the gas contracts. By contracting, this allows outside atmospheric pressure to do the work of returning the piston to TDC. The gas by pushing to expand, by pushing, the volume increases, because it was heated to a higher temperature, using that...
- Thu Apr 25, 2024 6:54 pm
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 41
- Views: 365
Re: Isothermal Heat Transfer
From that article I thought this was interesting. Something I haven't seen before: So for 𝑇 > 𝑇inv, an expansion at constant enthalpy increases temperature as the work done by the repulsive interactions of the gas is dominant, and so the change in kinetic energy is positive. But for 𝑇 < 𝑇inv, expans...
- Thu Apr 25, 2024 5:07 pm
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 41
- Views: 365
Re: Isothermal Heat Transfer
..., I would imagine the biggest reduction in temperature would be from expanding gas into a vacuum where the gas is able to use all it's kinetic energy to expand unrestricted. Actually it's just the opposite. When expanding into a vacuum the gas has nothing to do work against so doesn't loose ener...
- Thu Apr 25, 2024 8:06 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 41
- Views: 365
Re: Isothermal Heat Transfer
the internal gas pressure is still contributing, still doing work and still actually losing internal energy so still dropping in pressure and temperature due to work output. This is the part I'm having trouble with. The working fluid can only still be doing work while it's above ambient pressure, b...
- Thu Apr 25, 2024 7:49 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Ringbom-Rice conversion?
- Replies: 23
- Views: 434
Re: Ringbom-Rice conversion?
Some late night experimenting, but no great results so far. https://youtu.be/AaEfauPTqYo?si=0oBcnqy-1X2BbVqA If the flywheel assembly is removed, which can be accomplished rather quickly by just loosening the big hose clamp, the engine will run, apparently quite strongly. Put the flywheel back on an...
- Thu Apr 25, 2024 5:34 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 41
- Views: 365
Re: Isothermal Heat Transfer
Only if some working fluid has been bled from the engine at working temperature near TDC. Otherwise, you're not going to get the partial vacuum at BDC needed for the ambient atmosphere to do any pushing on the return stroke. Negative. We are seeing a strong return stoke with these engines while hav...
- Wed Apr 24, 2024 11:14 pm
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 41
- Views: 365
Re: Isothermal Heat Transfer
I've been avoiding the rock analogy. But to me rolling the same rock up and down a hill seems pointless. How about we ask, if the expansion stroke rolls a rock uphill, can the return stroke roll another rock up the same hill, thus performing more useful work? Not exactly. The point is, in doing wor...
- Wed Apr 24, 2024 10:36 pm
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 41
- Views: 365
Re: Isothermal Heat Transfer
If your asking me, conversion of heat into work is a "refrigeration effect" of a sort. I'm still working out exactly what I am asking so bear with me lol. And I mean thermal efficiency. Air cools down when it expands, and heats when it's compressed. If the air cools down further than it w...
- Wed Apr 24, 2024 5:25 pm
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
- Replies: 348
- Views: 12111
Re: The TRUTH? η = 1 – (Qc / Qh) = 1 – (Tc / Th)
There is a good reason why these equations are turning out with the values of 100 = 400. Because according to the Carnot limit, the 100 joules of heat added is not just in some kind of RATIO. It says, mathematically that the heat supplied actually IS all the heat down to absolute zero because it tri...
- Wed Apr 24, 2024 4:15 pm
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 41
- Views: 365
Re: Isothermal Heat Transfer
I mean, we are only talking about a piston returning to TDC after being pushed "up hill" against 1 atmosphere. Similar to lifting a weight against gravity or winding a spring. If it is "harder" to lift a heavier weight, the equivalent is still stored as "potential energy&quo...
- Wed Apr 24, 2024 3:03 pm
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 41
- Views: 365
- Wed Apr 24, 2024 2:52 pm
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 41
- Views: 365
Re: Isothermal Heat Transfer
I mean, in principle. If you store "potential energy" in a bolder, by rolling it up a hill, it can then roll down. I don't think this is any different then driving out a piston "up hill" against atmospheric pressure. It can then return. But what happens when the bolder reaches th...
- Wed Apr 24, 2024 11:41 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 41
- Views: 365
Re: Isothermal Heat Transfer
In that case, I'd say 70 units of heat would be "rejected" to the room. The rest going out as "work" is tied up as potential energy in the lifted weight. Ok, now were getting somewhere. Now how do we tie in the theory that there is a potential lowering of gas temperature and ref...
- Wed Apr 24, 2024 10:19 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Isothermal Heat Transfer
- Replies: 41
- Views: 365
Re: Isothermal Heat Transfer
The engine is perfectly insulated so no heat is lost other than what is exhausted or rejected to the sink. The heat is supplied to the engine within the confines of an isolated chamber so as to not heat the room directly. The only thing heating the room is what is exhausted/rejected to the sink. In...
- Wed Apr 24, 2024 9:42 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Why can't I "just buy" a stirling engine?
- Replies: 39
- Views: 8507
Re: Why can't I "just buy" a stirling engine?
Basically looks like the "hot" piston has been entirely replaced by a displacer, or perhaps regenerative displacer of some sort, but no longer an Alpha type piston.
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