confusion based around self-acting engine

[vasik041]

Hi Blitzkrieg,

Perhaps it would be interesting for you to read this page http://vasik041.wordpress.com/

If you scroll down you see some explanations about Tesla's FE principle and also examples of possible systems based on the principles.

-V.

[mthompson]

Blitzkrieg:

I've been working on a sort of spin off of Tesla's environmental energy extraction engine, and had to look up some of these equations a while back and while headaches are the main thing I remember about them I did get some help off another forum and also found a decent nasa site, see below, that is helpful. Hopefully I managed to select the appropriate basic formulas and used them correctly, but in fact it mainly boiled down to a monkey see, monkey do experience. I don't even pretend to understand the complex of inter-related equations they use - I somewhat doubt if even the people that work with them everyday do.

Having said that, in regards to TinselKoala's use of a ^0.4 factor, it would seem that it should be something more like 0.286 as the nasa page shows it being calculated using [1-(1/y)], where y is gamma = Cv/Cp = 1.4, so [1-(1/1.4)] = 1-0.714 = 0.286. There is also a slightly different method which uses [(y-1)/y] = [(1.4-1)/1.4] = .4/1.4 = 0.286. Like I said just a bunch of headaches... Anyway if the factor is more like 0.286 then T2 would be closer to 660K, but then I wouldn't bet my life on it.

Here is an extract from what I've been working on which briefly talks about the Heat of Compression and shows how I used the equations. I would appreciate anyone's comments on their correctness or wrongness for that matter.
.........

The Heat of Compression relates to the fact that as a gas is compressed the energy required to maintain the now reduced mean distance among its unceasingly agitated constituent molecules is decreased and this now excess energy either radiates away or goes into raising its temperature and pressure. For instance the surface area of a 1 cubic meter sphere is around 4.836 square meters, while that for 0.5 cubic meters is about 3.046 square meters. The surface area of the larger sphere is about 158% of the smaller, while inversely the surface area of smaller is only about 63% of the larger. It is pretty easy to see that if all the molecules that fill a larger space are crammed into a smaller one, or vice versa, the number of impacts per unit of surface area is going to drastically change, as is the mean distance a molecule can travel before a collision occurs.

To see how this works lets compress 2 cubic meters of ambient air (14.7psia, 288 degrees Kelvin, density of 1.2kg/cubic meter) into a 1.0 cubic meter volume. First let's do it the easy way following Boyle's Law which lets the heat-of-compression go off on its own so pressure is a simple inverse function of volume.

Boyle's Law: P2=P1V1/V2 = (14.7psia*2cubic meters)/1cubic meter = 29.4psia

Now let's try it when there is _no_ heat loss. *(note: I'm not a mathematician so beware..) The sign 'y' = gamma = cp/cv = 1.4; gas constant 'R' = cp - cv = 0.287 kj/kg/K; rho = density kg/cubic meters.

P2 = P1(V1/V2)^Y = 14.7psia(2/1)^1.4 = 14.7psia*2.639 = 38.79 psia

T2=T1(P2/P1)^(y-1)/y = 288K(38.79psia/14.7psia)^(0.286) = 288K(2.639)^(0.286) = 288K * 1.32 = 380 degrees K
*[equations from: grc.nasa.gov/WWW/K-12/airplane/compexp.html]

temperature check: T2 = T1(rho2/rho2)^Y-1 = 288K(2.4/1.2)^0.4 = 288K*1.3195 = 380 degrees K

[mthompson]

Tesla published an invention for getting energy out of ambient air? I dont remember it.

FYI: the relevant section is perhaps two thirds the way down the page

The Problem Of Increasing Human Energy, With Special References To The Harnessing Of The Sun's Energy

The Century Illustrated Magazine, June 1900.

".. I finally conceived a combination of apparatus which should make possible the obtaining of power from the medium by a process of continuous cooling of atmospheric air. This apparatus, by continually transforming heat into mechanical work, tended to become colder and colder, and if it only were practicable to reach a very low temperature in this manner, then a sink for the heat could be produced, and energy could be derived from the medium.".

".. the primary object of which was to secure the greatest economy of transformation of heat into mechanical energy. A characteristic feature of the engine was that the work-performing piston was not connected with anything else, but was perfectly free to vibrate at an enormous rate."

".. the engine which I have named "the mechanical oscillator." In this machine I succeeded in doing away with all packings, valves, and lubrication, and in producing so rapid a vibration of the piston that shafts of tough steel, fastened to the same and vibrated longitudinally, were torn asunder. By combining this engine with a dynamo of special design I produced a highly efficient electrical generator, invaluable in measurements and determinations of physical quantities on account of the unvarying rate of oscillation obtainable by its means. I exhibited several types of this machine, named "mechanical and electrical oscillator," before the Electrical Congress at the World's Fair in Chicago during the summer of 1893, in a lecture which, on account of other pressing work, I was unable to prepare for publication. On that occasion I exposed the principles of the mechanical oscillator, but the original purpose of this machine is explained here for the first time."

"In the process, as I had primarily conceived it, for the utilization of the energy of the ambient medium, there were five essential elements in combination, and each of these had to be newly designed and perfected, as no such machines existed. The mechanic oscillator was the first element of this combination, and having perfected this, I turned to the next, which was an air-compressor of a design in certain respects resembling that of the mechanical oscillator. Similar difficulties in the construction were again encountered, but the work was pushed vigorously, and at the close of 1894 I had completed these two elements of the combination, and thus produced an apparatus for compressing air, virtually to any desired pressure, incomparably simpler, smaller, and more efficient than the ordinary."

http://www.tfcbooks.com/tesla/1900-06-00.htm