Search found 102 matches
- Wed Oct 20, 2021 4:17 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Stirling Engine Thermodynamics
- Replies: 251
- Views: 103734
Re: Stirling Engine Thermodynamics
Far from being a curiosity, in my solar engine, the water vapor condenses in the power cylinder and will slow it down and then stop it. Have you tried using silica gel (or other dessicant) to dry your air? It doesn't need to be pressurised to do this, you just need a decent seal to ensure that the ...
- Mon Oct 18, 2021 5:22 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Stirling Engine Thermodynamics
- Replies: 251
- Views: 103734
Re: Stirling Engine Thermodynamics
If it helps, bear in mind that some commercial Stirlings use Hydrogen or Helium as the working gas, so no mixture or water vapour effects. As far as I know, these are more efficient, but don't work substantially differently from air-based engines.
- Fri Oct 15, 2021 8:46 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Stirling Engine Thermodynamics
- Replies: 251
- Views: 103734
Re: Stirling Engine Thermodynamics
Tom, I see you mention "molecular attraction" again - I'm not aware that any common gas has this property; indeed I was under the impression that a truly un-constrained gas would expand to fill whatever container it is in, regardless of temperature and pressure. Maybe I'm misunderstanding ...
- Wed Oct 13, 2021 8:16 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Stirling Engine Thermodynamics
- Replies: 251
- Views: 103734
Re: Stirling Engine Thermodynamics
"Why do these various engines have heavy weights on the diaphragm "pistons"?" I suspect the main reason is that the engine is at atmospheric pressure inside, at rest. Once the engine has been 'fired up' the internal pressure will rise substantially. For a diaphragm-based engine i...
- Tue Oct 12, 2021 5:05 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Stirling Engine Thermodynamics
- Replies: 251
- Views: 103734
Re: Stirling Engine Thermodynamics
I quite agree with Tom: the mass of a piston is directly _ counter _ to the ideal operation of _ any _ engine - a massless piston is always going to be better overall than a heavy one.
- Thu Oct 07, 2021 9:10 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Programmatic control of Stirling Engines
- Replies: 30
- Views: 18701
Re: Programmatic control of Stirling Engines
To be positive for once - you don't need to measure temperature - you have a known (though not entirely fixed) volume of gas, so if you are able to measure the pressure then you can calculate the temperature from that. Whether pressure sensors are significantly faster than temperature sensors I have...
- Tue Oct 05, 2021 4:50 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Programmatic control of Stirling Engines
- Replies: 30
- Views: 18701
Re: Programmatic control of Stirling Engines
That video of adiabatic bounce is quite a clever demonstration, but I have to point out: As you note, no REAL work is done - in our nice, perfect frictionless theoretical world, the 'piston' will continue to oscillate perpetually. But without doing any work, which is the fundamental point of any eng...
- Wed Sep 29, 2021 9:12 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Programmatic control of Stirling Engines
- Replies: 30
- Views: 18701
Re: Programmatic control of Stirling Engines
Water is not energy, only a carrier of gravitational energy. The bottom video shows that that particular water wheel is rather inefficient since much of the water is being thrown clear. My problem with the experiment you describe above is that heat transfer is happening in three phases, not one: Fla...
- Tue Sep 28, 2021 12:23 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Have you seen the dual-power stroke mod Stirling made to 1816 engine?
- Replies: 11
- Views: 3345
Re: Have you seen the dual-power stroke mod Stirling made to 1816 engine?
If you want to know more about how that works, look up "Parallel Motion" which was used on steam engines long before Stirling came along.
- Mon Sep 27, 2021 5:35 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Have you seen the dual-power stroke mod Stirling made to 1816 engine?
- Replies: 11
- Views: 3345
Re: Have you seen the dual-power stroke mod Stirling made to 1816 engine?
Gary, sealing is actually one of the advantages of using a double-acting power piston - any leakage past the piston itself goes into the other half of the engine, rather than being vented, and then presumably leaks straight back the other way after 180 degrees. Sealing the various con-rods is an inh...
- Mon Sep 27, 2021 5:29 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: I want to build a high efficiency Stirling electric generator
- Replies: 23
- Views: 11563
Re: I want to build a high efficiency Stirling electric generator
How was that 40% calculated / measured?
Most of us are used to _ slightly _ lower numbers than that...
Most of us are used to _ slightly _ lower numbers than that...
- Mon Sep 27, 2021 5:27 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Why are strokes are so much shorter than Stirling's?
- Replies: 1
- Views: 1830
Re: Why are strokes are so much shorter than Stirling's?
Pretty much everything is inter-dependant: materials; temperature difference; power; speed
Those numbers don't look very different to what I would expect for modern power-producing machines - LTD models are at the opposite end of the spectrum due to that pesky "Low" in the name.
Those numbers don't look very different to what I would expect for modern power-producing machines - LTD models are at the opposite end of the spectrum due to that pesky "Low" in the name.
- Mon Sep 27, 2021 5:24 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Programmatic control of Stirling Engines
- Replies: 30
- Views: 18701
Re: Programmatic control of Stirling Engines
"It is well know that it takes TIME to transfer heat by conduction" Yes, that is one of the real-world compromises that we face - the longer we have for heat/energy transfer (in either direction) the more will transfer, but even at zero RPM the air on the inside will never reach the temper...
- Mon Sep 20, 2021 4:26 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Programmatic control of Stirling Engines
- Replies: 30
- Views: 18701
Re: Programmatic control of Stirling Engines
The energy introduced as heat is "let out" as mechanical "work". This is what I was trying to get at with the wind-turbine analogy - you missed out the word "some" above - _some_ of the energy in the air inside the engine gets transferred to work done by moving the pis...
- Fri Sep 17, 2021 7:23 am
- Forum: Stirling and "Hot Air" Engine Forum
- Topic: Programmatic control of Stirling Engines
- Replies: 30
- Views: 18701
Re: Programmatic control of Stirling Engines
I was once told that "All models are wrong, but some are still useful." The Carnot idea of heat as a fluid is a useful concept most of the time, but I don't think I've ever seen anyone suggest that it can be 'intercepted'. Similarly many of these conversations try to cover too much ground,...