Centrifugal forces and heating

[ds721]

Hi,

I would like to know why this mechanical machine can't works ? The idea is to recover energy from one source of heating with help from centrifugal forces. At 20°C the mean speed is around 500 m/s and this say the machine must turn at least at 5000 r/min with a radius of 1 meter, it's possible to think with bigger radius for have shape of cylinder/valve like drawing. On drawing I zoom+ the cylinder for detail how gas are in it. The valve turn only at 5000 r/min, it's the cylinder that recover energy from heating when it translating. Cylinder turn like valve at 5000 r/min but sometimes it turn around the axis of valve for repeat cycle. The gas last/win energy from rotating but in a complete cycle the gas win/lost nothing from centrifugal forces, it's possible to imagine gas without temperature, this system can't win/lost energy or maybe from friction. I'm sure this need calculations but maybe you can see where this system can't works ?


Thanks
Regards

 

[willard3]

Hire an Engineer familiar with this equipment and read forum policies which begin as follows:

>>>>>>>>These fora should not be used to bypass your own in-depth research on the issues that affect you, nor is it intended to be a substitute for appropriate professional assistance within your field or geographical region.>>>>>>>>>>>

 

[ds721]

Oh, sorry, I don't see that point. So, you can destroy my post.

 

[EnergyMix]

Simply put, it's a perpetual motion machine. You have to impart energy to get it going and the force of friction will slow it down over time, whereupon you will have to impart more energy to start it up again. But go ahead an invest money in it if you want.

 

[ds721]

yeah it's not possible (I don't want to lose money in something like that) but I would like to know where is the error exactly. If I imagine gas without temperature, the system lost nothing except friction but all turn at the same speed. One time I thought the system lost energy with the difference of speed of gas but with a big radius this difference is small compare to the energy recover from temperature. And if you imagine this system with gas at 0°K, the system win or lost nothing except friction, so it's not possible that is the speed that change something. Maybe this system has been study, have you a link ?

 

[EnergyMix]

Not an engineer, are you?

 

[ds721]

I'm engineer but in electrical field (ENSI), I know only basic laws in thermodynamic

 

[prex]

Can't understand your setup. What is the purpose of the centrifugal force exactly? Of course it will heat up the system because of friction, but I suppose you know that the transformation of mechanical energy into heat is a losing process.


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[ds721]

I add another drawing for showing details. The centrifugal forces change the repartition of pressure inside cylinder. The gas push cylinder at external and the valve at external too. But the valve turn only at 5000 r/min, don't move in translation. The cylinder turn at 5000 r/min and move in translation for recover energy (if possible). After, rotate the cylinder around X axis of 180° and return to start another cycle. I don't see where are friction ? The rotation at 5000 r/min is constant, never change. Like all system turn at same speed than gas (5000 r/min), the temperature of gas don't change for me. I show only transfer of energy when the cylinder rotate around X axis, but with a big radius like for example 10 meters and the same cylinder 10 cm, the transfer is limited I think.

 

[chicopee]

Being a two stage cylinder, in one stage the gas is compressed and heats up and in the second stage the gas expands and cools. As you rotate the cylinder about point "0", the centrifugal force minus frictional force will compressed air on the outside stage and an expand air on the inside stagee. You would think that the hot side (compressed air side) will now expand and compress the cool side during the rotation but that will not happen much because you have to overcome the centrifugal force and the friction. You'll be lucky if the piston returns to its neutral position. You need to increase the internal energy of the hot side for what you want to happen.

 

[prex]

A bit clearer now, but still I can't see what you call the valve and how you are planning to extract energy from a body turning at that speed.
Anyway I think the point is that to turn the cylinder around x axis you must spend energy (work) as you need to overcome the centrifugal force displacing the cylinder to a shorter radius, and I guess (didn't think of this in depth) that this work is equivalent to the energy spent to compress the gas (plus of course the losses due to gas heating). So no net energy output, but only consumed energy.

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[ds721]

I thought that, but after translating and recover energy, imagine you place external gas in a box closed, and internal gas in another box closed, this cost nothing. Place internal box at external position in cylinder and external box at internal. Open boxes. This cost near nothing if the radius is very high (possible in theory, example radius = 1000 m and the length for the cylinder somethink like 30 cm), in fact it's only a cost from kynetics energy but nothing compared with temperature. In this case, do you think the energy lost for move boxes is the same than energy won in translating ?

 

[ds721]

I now understand, it's because I increase temperature of gas when I move it in original position. So, this would say with a system like drawing must recover energy ? When the cylinder is in part of circle, move it in translation and recover energy. When cylinder is in right line, replace the cylinder like start position.

 

[IRstuff]

It's generally easier to recover 100J from a mL of water than it is to recover the same amount from 1000mL, i.e., your proposal is dealing with very low delta temperatures, so the odds are not in your favor.

TTFN
faq731-376

 

[ds721]

ok, the centrifugal forces can't create in one side pressure and other side vacuum on a high distance ?

 

[IRstuff]

The math is is high school physics; perhaps you can crack open an old textbook.

TTFN
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