Stirlingengineforum.com

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.

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...

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...

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...

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.

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...

How was that 40% calculated / measured?

Most of us are used to _ slightly _ lower numbers than that...

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.

"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...

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...

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,...

I think the point that M13Calvin was trying to make is that if you were _able_ to build an engine that was optimised for adiabatic operation, and was 'perfect' in all other regards, it wouldn't be 100% efficient. This is unfortunately true for any engine, of any type - there is a theoretical limit t...

That is going to be a difficult question to answer, and potentially counter-intuitive too! A load of tarmac will certainly heat up a lot in direct sun, but not sure how good the heat conductivity would be - if there is too much insulating effect (as with the compost heap) then you won't get much tra...

That's the strength I see of this - the ∆T comes from two theoretically inexhaustible sources - the mountain stream, and the well tended compost heap. Whoa! The stream is a great source of cooling, but the compost heap not so much, nowhere near to inexhaustible in fact! The point is that you need t...

40 degrees F is kind of mid-range territory for a tea-cup model - some LTD engines can go as low as 4 degrees or so. On the other hand, for a power-producing machine it is tiny - they tend to operate with more like 400 degrees difference, so don't expect to run your house off it! Without knowing how...