Boiling Water?

ERRORIST · 2004-12-28 09:25:03

What is in those bubbles of boiling water? Is O2 seperated from H2?

Palomar · 2004-12-28 09:28:05

What is in those bubbles of boiling water? Is O2 seperated from H2?

*Um...I don't know, but it (boiling water) seems to be the limit to many peoples' cooking abilities! :laugh:

--Cindy

ERRORIST · 2004-12-28 10:10:43

Yea, and if you mess up you get boiling mad!!

GCNRevenger · 2004-12-28 10:21:23

No, at normal atmospheric pressure, the bubbles are still H2O, they are just H2O gas. Water can exsist in any of the three common phases. You would have to get water hotter, LOTS hotter, to weaken the chemical bonds.

ERRORIST · 2004-12-28 10:25:09

How much hotter?

GCNRevenger · 2004-12-28 10:33:22

I don't know the exact temperature, but I do know that the bonds don't start weakening until you hit 400-500C.

ERRORIST · 2004-12-28 15:34:36

Anyone ever try to ignite it at or above those temps?

GCNRevenger · 2004-12-28 15:53:45

Sure you can heat up steam in a sealed furnace... I bet it would start to come apart in the 1,500-2000C range.

ERRORIST · 2004-12-28 16:11:06

Can you isolate the H2 molecule at those temps and seperate them from the O2 molecules?

GCNRevenger · 2004-12-28 16:38:11

That might be tricky... if H2/O2 will spontainiously combust at reduced temperatures, then it might not be practical to cool and liquify them. If you can get them into a liquid state, then the Hydrogen can be easily distilled off. I can't think of an easy way to seperate the ultrahot gasses though.

ERRORIST · 2004-12-28 18:42:27

If they disassociate at those temps would the lighter H2 stay near the top and the heaver O2 stay near the bottom?

Ian Flint · 2004-12-29 12:59:34

With such excited hot molecules both O2 and H2 would be mixed rather homogenously in any normal container. Maybe you could use a centrifuge.

ERRORIST · 2004-12-29 19:10:57

My exact thoughts? Perhaps,this would work if you spun it up quick?? The H2 should stay in the center and you could tap the H2 from the center while the more heavy O2 would stay to the outside??

GCNRevenger · 2004-12-29 20:04:44

No, the centrifuge would not be very practical since it would have to be kept so hot. 1500C is hotter then steel can reliably survive.

Errorist, have you heard of the Sulfur/Iodine cycle? It is a chemical process where water is broken down into its elements through a series of reactions, with sulfur and iodine acting as catalyst. The gasses are expelled seperatly, so no seperation is required, and the only thing required to operate the device is heat.

Electrolosys is also a very easy albeit energy intensive way to crack water, around half as efficent as the S/I cycle for thermal energy, but has very forgiving conditions and is well suited to operate from solar arrays.

ERRORIST · 2004-12-29 20:20:04

No, the centrifuge would not be very practical since it would have to be kept so hot. 1500C is hotter then steel can reliably survive.

Ok so you can insulate the steel as they do in our furnace at the army depot where the furnace rages at 2000 degrees F.

GCNRevenger · 2004-12-29 21:35:40

In space or on Mars where the air is thin though, there won't be anywhere for the heat to go. You would have to include an active cooling system. The superhot oxygen will also corrode most metal containers rapidly just like a blowtorch.

Heating water until it breaks apart is just not very efficent to begin with, it takes alot of energy to raise the temperature of a signifigant mass that high, and even more to operate the centrifuge to seperate it. Sulfur/Iodine or HT electrolosys are much more efficent.

ERRORIST · 2004-12-29 21:53:21

In space or on Mars where the air is thin though, there won't be anywhere for the heat to go. You would have to include an active cooling system. The superhot oxygen will also corrode most metal containers rapidly just like a blowtorch.

What if you used tungsten carbide as the container and insulated it then spun it up. The O2 or heat should not affect it to much as long as it is insulated. I tried to cut tungsten carbide with a blow torch and I could barley get it to melt. It turned white hot.

GCNRevenger · 2004-12-29 22:35:20

I imagine that very few materials would handle the corrosive effects of superhot oxygen for long Errorist, even materials like WC. We're not talking minutes Errorist, this is more for hours... oxygen is quite corrosive actually in extreme conditions like this. It isn't the heat I'm worried about.

This is still a very inefficent way to crack water, the sulfur/iodine cycle only needs to get half as hot, and HT electrolosys about 1/4th as hot.

ERRORIST · 2004-12-29 23:00:10

the sulfur/iodine cycle only needs to get half as hot

What are the byproducts of this method? Any poisionous gasses?

GCNRevenger · 2004-12-30 15:21:41

No byproducts, the system is theoretically a closed loop, the details are in the plumbing.

The intermediates are quite toxic and fairly corrosive, but they stay in the machine.

Edit: http://www.cmt.anl.gov/science-technolo … ical.shtml

Even more efficent

ERRORIST · 2004-12-30 16:36:59

How much heat is generated by the friction on the wings on the aircraft at those velocities?

BWhite · 2004-12-30 16:46:27

No byproducts, the system is theoretically a closed loop, the details are in the plumbing.
The intermediates are quite toxic and fairly corrosive, but they stay in the machine.
Edit: http://www.cmt.anl.gov/science-technolo … ical.shtml
Even more efficent

If your nuclear reactors have a secondary coolant loop pressurized with water - - and the pressurized hot water fed into a chamber with catalysts and replaced with new water - - wouldn't this increase the overall efficiency of your reactors?

The two most highly developed thermochemical cycles are the sulfur-iodine and the calcium-bromine cycles. Both contain at least one reaction that requires temperatures greater than 750ºC. Process heat in that range (750-850ºC) could be provided by next-generation nuclear power plants.

Copper-chlorine appears to be at 550 degrees C - - can we a design a Mars reactor to spin off coolant water at that temperature? Or if we are close, heat the water with a "relatively' small input of additional energy?

Edited By BWhite on 1104447022

GCNRevenger · 2004-12-30 17:10:23

The idea would be to use the coolant, whatever it is, and pass it through a dedicated heat exchanger to operate the thermochemical cycle Bill. You definatly don't want to be putting reactor coolant in your gas tank.

This copper/chlorine cycle looks especially attractive in that it might run just cool enough to use the waste heat from a nuclear reactor after the coolant has been through the turbines to make electricity, which would increase the efficency of the whole contraption.

Or be able to produce a reactor that operates much cooler to produce only hydrogen and oxygen that would be way easier to build, even use stainless steel instead of zirconium and graphite and such.

The conversion isn't much better though, so this process wouldn't make the reactor thermal conversion much better.

This process would be way easier to use with solar thermal methods too.

Errorist: You are forgetting to think about the thermodynamics again. Where does the energy that makes the friction on the airplane come from? It comes from the burning of fuel in the engines. Since you can't get more energy out of a system then you put into it, you would still run out of fuel, it would just take a little longer.

BWhite · 2004-12-30 17:20:53

The idea would be to use the coolant, whatever it is, and pass it through a dedicated heat exchanger to operate the thermochemical cycle Bill. You definatly don't want to be putting reactor coolant in your gas tank.

That is what I meant by "secondary" coolant loop - - sorry for the incorrect term. I agree, this water cannot go anywhere near the reactor itself.

Solar thermal?

Can focused solar collector arrays reach 550C - - even on Mars? If so, rovers could deposit tanks of water at automated refueling depots as they travel and collect H2 when they return.

Edited By BWhite on 1104448907

GCNRevenger · 2004-12-30 17:38:28

Also to point out, water as reactor coolant may be going out of style... big space nuclear reactors almost exclusively use Sodium or Potassium (some little Russian ones use Cesium) metal for primary coolant, and Pebble Bed reactors and space nuclear secondary coolant is Helium or a mix of noble gasses.

Prometheous is looking to build such a reactor, but I question if its such a good idea versus the Russian or SP-100 style reactor that doesn't have a secondary loop.

...Solar energy top 550C? On Earth or in Cis-Lunar space, sure no problem. Mars... trickier, but not outside the realm of reason. Straight nuclear would be preferable for a Mars fuel depot since it would be more reliable and compact. A small reactor designed to use this cycle would be stupid-easy to build probobly.

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#1 2004-12-28 09:25:03

Re: Boiling Water?

#2 2004-12-28 09:28:05

Re: Boiling Water?

#3 2004-12-28 10:10:43

Re: Boiling Water?

#4 2004-12-28 10:21:23

Re: Boiling Water?

#5 2004-12-28 10:25:09

Re: Boiling Water?

#6 2004-12-28 10:33:22

Re: Boiling Water?

#7 2004-12-28 15:34:36

Re: Boiling Water?

#8 2004-12-28 15:53:45

Re: Boiling Water?

#9 2004-12-28 16:11:06

Re: Boiling Water?

#10 2004-12-28 16:38:11

Re: Boiling Water?

#11 2004-12-28 18:42:27

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#12 2004-12-29 12:59:34

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#13 2004-12-29 19:10:57

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#14 2004-12-29 20:04:44

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#15 2004-12-29 20:20:04

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#16 2004-12-29 21:35:40

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#17 2004-12-29 21:53:21

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#18 2004-12-29 22:35:20

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#19 2004-12-29 23:00:10

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#20 2004-12-30 15:21:41

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#21 2004-12-30 16:36:59

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#22 2004-12-30 16:46:27

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#23 2004-12-30 17:10:23

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#24 2004-12-30 17:20:53

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#25 2004-12-30 17:38:28

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