Thermal Propulsion!

[bellbottom25]

Hi,

Is there any physics theory where heat generated from a source can be made to displace water in metallic pipes when heated from one end to another!????

Like for moving an object like ship by this theory!

 

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eric

[DrP]

The steam could then drive a turbine to generate electricity as in a powerstation. Or as you say a ship could be propelled by steam power by having the steam pressure build up and used to push a piston. Look up steam engines.

[insane_alien]

yep, sounds like a steam engine to me. he may be thinking more along the lines of a jet effect like the aeolipile rather than a turbine or piston.

[kevinalm]

It probably wouldn't be practical for moving a ship, but how about a fluidyne engine/pump?

 

http://en.wikipedia.org/wiki/Fluidyne

[Edtharan]

Have a look at this web site:

http://www.sciencetoymaker.org/boat/index.htm

 

These boat engines use the hear of a small candle to flash boil water into steam, this steam pressure pushes a column of water out of the engin thus pushing the boat forwards. Then the steam condenses and water rushes back into the engine ready to be flash boiled again.

[insane_alien]

ah, external combustion pulsejet.

 

i thought of that one but i couldn't find it on google.

[bellbottom25]

Have a look at this web site:

http://www.sciencetoymaker.org/boat/index.htm

 

These boat engines use the hear of a small candle to flash boil water into steam, this steam pressure pushes a column of water out of the engin thus pushing the boat forwards. Then the steam condenses and water rushes back into the engine ready to be flash boiled again.

 

I have played with putt boat then. What do you mean by -the steam condenses and water rushes back into the engine ready to be flash boiled!???

When i saw the diagrams there was no mention of such...i mean its just written that the water in the column boils by the candle and is expelled through pipes. Or is it like a chamber inside the boat!? The extra water is kept in the boat structure which gets introduced into the heat chamber when perhaps might be vacuum is created when water is expelled earlier by heat! Then was the water filled up to the brim of the boat! Then how the candle was lighted?

 

Anyway when i had seen it, i thought like that it was moving with hocus-pocus! (with that candle)!

 

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eric

[insane_alien]

the water is only in the pipe. the water boils, forces water out then when the steam hits the submerged portion of the pipe it condenses rapidly creating a vacuum which sucks in more water which gets boiled ... repeat until candle goes out.

[bellbottom25]

the water is only in the pipe. the water boils, forces water out then when the steam hits the submerged portion of the pipe it condenses rapidly creating a vacuum which sucks in more water which gets boiled ... repeat until candle goes out.

 

Blah! It would be impossible for the water to be again introduced into the chamber even if there would have been vacuum created. If it would be then it would be only 30 to 40 percent than it was filled manually before even litting the candle! As i have myself seen the boat itself stops after some time.

The diagram also seems wrong the thermostat flap whose one end should be under the flame lit and the other end inserted into the chamber. The heat transmission then boils the water! Might be that the air pressure created due to steam expells the water through the pipes. But i am unsure of water introduction!

 

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eric

[Edtharan]

What do you mean by -the steam condenses and water rushes back into the engine ready to be flash boiled!???

Well it dosen't usually push all the water out of the pipe, so ther is still water in the pipe.

 

But, when you heat water into steam, it take up more room that water as a liquid. Therefore, when the water boils in the pipe, it must push some of that water out of the pipe. However, once all the water in the pipe has been boiled into steam, then there will be no more expansion, but since the water in the tube will have momentum as it is pushed out, it will continue to move out of the tube without the pressure of the steam.

 

This creates a vacume (and expanding a gas like that cools it down which then means that the steam will take up even less room). Also the heat energy in the metal of the pipe will have been used up in flash boilingthe water, which now mean it is less that 100 degres C. As the temperature is now less than boiling and the slight vacuum has colled the steam it will condense creating more of a vacuum.

 

This vacuum "sucks" water back up the pipe, and in the mean time the pipe is being reheated by the candle (or other heat source) so that when the vacuum has sucked the water back in, there is enough temperature in the pipe to flash heat the water again, and the cycle repeats.

 

It is actually this cycle that give the engine its name. The "Putt" sound is when the water flash boils. Then as the steam condenses and creates the vacuum that sucks more water back into the engine (from outside the boat), ther eis a pause in the sound. Then in the next cycle the water is flash boiled and you get another "Putt" sound. And so you get this nice Putt, Putt, Putt sound.

 

The extra water is kept in the boat structure which gets introduced into the heat chamber when perhaps might be vacuum is created when water is expelled earlier by heat! Then was the water filled up to the brim of the boat! Then how the candle was lighted?

No, the ends of the engine (what look like exhaust pipes) should be under the water. This allows water to flow back in when the vacuum forms.

[bellbottom25]

I think i ought to be running with a mug filled with water for pouring over the chamber for heat dissipation/cooling, otherwise it would seem that the boat is moving with the generated steam with pressure after the water expulsion! In other words Cracking my thermos!

 

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eric

[YT2095]

there May be a way to do it I think, I have a Passive liquid cooled heatsink here, it consists of a oval pipe filled with some sort of liquid, and one side of the pipe are loads of heatsink fins, the place where you mount the semiconductor is Offset to one side somewhat.

this causes currents in the liquid and forces the hot liquid past the cooling fins and back out to recirculate again.

 

now this is a closed system and no way of getting energy out exactly, but what if discrete NIB magnets were inside the tube that traveled with the liquid? then you could pick this up Outside as a type of Tractor effect.

[CaptainPanic]

Aren't we simply talking about a bottle rocket which uses steam in stead of air to push the water out?...

 

Put the bottle rocket horizontal, and build it out of steel, and you're good to go I'd say. (Make sure by the geometry that the liquid water comes out before the steam is lost).

[lakmilis]

Aren't we simply talking about a bottle rocket which uses steam in stead of air to push the water out?...

 

Put the bottle rocket horizontal, and build it out of steel, and you're good to go I'd say. (Make sure by the geometry that the liquid water comes out before the steam is lost).

 

LOL at 1st year undergrad aeronautical students ,p

[bellbottom25]

now this is a closed system and no way of getting energy out exactly, but what if discrete NIB magnets were inside the tube that traveled with the liquid? then you could pick this up Outside as a type of Tractor effect.

 

I didn't understood! Might be that putt-putt boats were made in huge size!

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eric

[cytodd]

Thia might be closer to what you're looking for:

 

http://www.newscientist.com/article/dn3321-steam-fires-underwater-jet-engine.html