Physicists help needed!!! Current technology limitations.

Yes, I certainly did - and I immediately came back, admitted I was wrong, apologized for not having brain in gear and corrected my mistake.

Which is MUCH more than can be said about the other person under discussion here. I doubt if he's had the honesty to ever admit a single mistake - and he made many more here than I ever did.

Please Register or Log in to view the hidden image!

And I've got absolutely nothing against self-education. If that was/is the case, all he had to do was say so. Actually, I believe that sort of thing should be highly commended. ( But he can't be commended for ducking and running.)

 

Log in or Sign up to hide all adverts.

A OK. Let's lighten up and move on and do some more good physics.

 

Log in or Sign up to hide all adverts.

Just got back to the site, last tests before finals and finals at school. Had to reply to this one first. I was just reading the additions to the post and I will have to admit I have skimmed a few posts already. Dislike the anamosity but like the contunued conversation. I will write more about that later. I just wanted to thank leopold99 for lightening the mood

Please Register or Log in to view the hidden image!

 

Log in or Sign up to hide all adverts.

A bomb calorimeter measures the heat loss of a chemical reaction. But YES that is my thought, using the heat produced from combustion to power a turbine/generator then transfering the energy to drive motors.

The whole heat pump conversation is very revalent, since I will need to recycle the working fluid that drives the turbine.

A small chamber injected with fuel and air plus a spark. I do not expect the explosion to do any direct work. I would like to harness the energy as heat. I am not certain given how much of an explosion can be harnessed with todays materials. It would seem the fuel usage would necessarily need to be much much lower. Just want to bring the engine, or better a core surrounding the engine up to the temperature needed by the working fluid to vaporize and drive the turbine/generator.

 

I am not sure what you want or what you know, but I think you are trying to realize a Carnot cycle engine, which is the most efficient closed-cycle thermal-engine possible. It takes all of the thermal energy in at one high temperture, T, as it expands the working fluid along an "isotherm" in the Pressure vs. Volume plot. Then it completely stops all thermal transfer, but continues expanding the w.f. along a "adibate curve" in the P.vs V. diagram. Then it establishes thermal contact with the lower temperature, t, heat sink and partially recompresses the w.f. as "waste heat" is exhausted. Finally stopping this and breaking all thermal transfer contacts, at just the correct point in the P.vs. V. drawing so that one adibatic compression leg will restore the original state (I.e. it is "closed cycle")

The efficiecy of this engine is: (T-t)/T where temperature is measured on the absolute scale. No other closed cycle is as good and this is realtively easy to [prove, but I don't do it - I only hint as to how: Imagine some other closed cycle in P vs V discription/ drawing. Break it up into many very small "adjacent" Carnot cycles with the isotherms all very short and the compressive adibate of cycle n+1 identical to the expansion adibate of cycle n. Calculate the work done of each cycle and energy input for each and compare to a single carnot cycle opertating between same T and t.

 

The Carnot equation says that you can only get the percentage of the hot side temperature that is greater than the cold side temperature. The cold side temperature is presumably the ambient temperature. The hot side temperature is the cold side temperature plus the temperature increase generated by whatever energy source you are attempting to use. Thus, the Carnot equation says that you can't get any more energy out of the heat engine than you put into it. It doesn't prove anything that we didn't already assume using the postulate of the conservation of mass and energy.

 

we could make use of waste heat in cars etc.. etc... with stirling engines, but then the car would be as big as a train.. and thus.. our effieciency is lost...

The Tesla Turbine gets 60% efficiency.. a good option.

and i am working on a low temp heat converter using principles which are old, and yet still unapplied...

-MT

 

Reason MT is correct about "train sized cars" if trying to use the waste heat in engine is that for closed cycle engines, like stirling (which is a practical approach to the prefection of Carnot cycle) is that the waste must transfer across a heat exchanger and the rate it crosses is proportional to the surface area and the temp difference. Thus if you want a small temp difference (so energy in the discard is not much above the air etc temp) you need a very large surfrace area in the heat exchanger.

A quick application of the Carnot limit with t = 300 & 60% efficiency shows that the Tesla Turbine must have a heat source of at least 750degrees K. I am an admirewr of N. Tesla (a scientist, but not the businessman that Edison was, so he lost their AC / DC contest util the phyics of it proved him right and Edison wrong) but I do not know about his turbine - a few words about it please.

Also as "the principle are old" please tell at least them, if you do not want to tell your ideas. But if you tell ideas, I may be able to tell you why it will not work and save you some effort. (i.e. I strongly doubt that use of waste heat for energy is pratical - but look at ocean thermal energy system to see some of the most advanced ideas for use of low tempreatures.)

 

The Tesla turbine was an interesting idea. It used a series of thin smooth disks stacked on the shaft and spaced apart by about the thickness of the disks. A lot like a multplatter hard drive. The disks were vented in the center. The housing dumped exhaust at the center. Working gas entered at the perifery of the disks and was directed tangently to them. He reported considerable success, in spite of the fact that the design flies in the face of conventional wisdom.

For some years I have had a pet theory about this turbine. I suspect that Tesla might have accidently stumbled on the principle of the vortex tube, only in reverse. That would explain how it could give a reasonably good efficiency. Just my s.w.a.g. though.

Please Register or Log in to view the hidden image!

 

Let's put it another way. I believe that any theoretical thermal efficiency by the Carnot formula equates to one hundred percent fuel efficiency.

 

The conversion of say fuel energy into heat... is 100%... but it comes out as heat...
and thus the problem... how to convert all of it into usable work.

The Tesla turbine works exactly as Kelvinalm just described...

but the unique quality of it.. is that tesla included a Valular conduit which was basically a one way value for the inlet of fuel and air.. very much like using a Pulsejet to drive the turbine....

anyway.. when the exploding gases meet the disks, which are spaced as close together as possible.. the gases will naturally follow a circular path towards the center.. and as the disks turn...
the action of the spinning disks, actually serves to hold back the gases, and so the gases are forced to make a greater number of orbits as they strive for the center and the exit...

Ie.. the turbine can be used as a compressor... pulling gas from the center, and literally throwing it outward towards the outer edges of the disks...

thus in operation, the motion of the disks serves to hold the pressure back, and so again the gases are forced to take many more trips around in circles, than they would have if the disks were not moving.. Hence the reason for the improved efficiency....
in this way the gases cross a maximum pressure differiential... and the exhaust gases are not much above normal airpressure... unlike normal turbines which release gases at still usuable pressures, and tempurtures....
Tesla said the problems he faced was that it worked best when the turbine blades were moving at 50% the speed of the moving gas... and as such... the disks must spin extremely fast... at in his day... the steel used wasnt strong enough and would tear it self apart at those spin rates... but today we have better steel, and alloys.

the Turbine it self worked on the principle of Adhesion and Viscosity... i.e.. gases when flowing past a surface do act apon the surface,... like wind across the ocean... the water is made to move with the wind...
likewise.. the adhesion and viscosity of the gas works well, but only if the disks are many and very closely spaced.. as in 1 mm apart or less... thus, the effects of Adhesion and viscosity become workable for our purposes...

I have studied Teslas work for a long time.


in regards to my proposals for Low temp heat conversion, im afraid i cannot express more than i have already.... thats how much i like the idea...
and i honestly know... its not a matter of whether it will work.. but it is a matter of how well it will work..

Regarding stirling engines, i think therein lies the future power source for our world..

Ie.. black body collectors can collect 90% of solar radiation.. and thus heat water.

and if the stored heat, by way of good insulation, was prevented from passing anywhere but across our stirling engine, then the efficiency can be high... and is limited to the design of the engine.. and the pressure of its working fluid...(gas)

also, ammonia boilers offer great promise.. the obsticle being in the cooling and pressurizing of the boiled ammonia..... yet... if we avail ourself to the use of massive cooling radiators, then the need for input energy to cool and compress the ammonia again may be avioded.. (ammonia boils at like 34 degrees c, like 80 F...)
(well in the range of warm water..... and so can be reach usable pressures.)

-MT

 

I didn't mention the fluidic valve because it isn't critical to the Tesla turbine. Steam versions for example. But it is another of Telsa's intriguing ideas. A valve with _no_ moving parts.

 

the Valular conduit is fascinating.....
-MT

 

They can do better than that - for example a simple hole in an insulated box at the focus of the collector can absorbe 100%, but absorbing solar radiation to produce temperatures high enough to be interesting (economically) for thermal conversion faces the loss of collected energy via radiation of IR.

I have an expired US patent on a unique solution to this problem, entitled "mass flow solar absorber." - I am not currently at home, so can not give the number, but I have briefly described how it works in posts here, published two related analytical papers in Applied Optics years ago, and given the number here several times. Perhaps a search of some threads will turn it up or someone reading may remember what thread it was in.

 

MgO????
-MT

 

I don't understand why you think that. It makes no sense.

 

It is the nature of the universe... Entropy.. all forms of energy can.. generally be turned 100% into heat.. or.. eventually.. it all ends up as heat anyway.

if all you want is to make heat... then it can be 100%..

problem is we want to make work.. or motion we can use...
and its is never 100%... we always have a % lost as heat...
so if all we want is heat... then we can have 100%..

-MT

 

Yeah MT, I understand entropy - MetaKron has a problem with the 2nd law of thermodynamics. I don't understand his take on what he calls "fuel efficiency".

 

I think that because it's what the equation says. If an engine achieves all of its Carnot thermal efficiency, it will have achieved one hundred percent fuel efficiency. The Carnot equation is one of the simplest equations that there is to interpret correctly.

I've been trying to give away the store on this one, betting that no one is going to take it. That's OK, it's not my loss.

 

MetaKron,

I see what you are trying to say now. What I didn't get was you said "any" theoretical thermal efficiency = 100% fuel efficiency.

You mean to say that if you could extract all the chemical energy from the fuel you'd have the theoretical maximum, which is the maximum given by the Carnot equation.

But so what? I guess I don't understand your beef with the thermodynamic model of the Carnot cycle. You just think it isn't helpful?