Little High Pressure Gas Generator

[Gerdih]

Lets say we wanna construct a little device that will provide us high pressure gas to activate some pneumatics systems or whatever we want.

Lets say the initial idea is to use H2O2 as a monopropellant to achieve such objective. We burn it with a catalyzer to obtain a high temperature gas. Common sense says us to use the energy of that gas to run a turbine to compress atmospheric gas. My question is, is it the best and efficient way to obtain the maximum high pressure gas we can obtain from H2O2?

Do you have any more ideas to achieve the objective like using gasoline? taking into account that the device that produces de gas must be little. Lets say 20cm*10*cm*5cm.

Thanks!

 

[Urwumpe]

I would spray water into the exhaust gases to cool the exhaust and increase the volume flow (the idea is thankfully stolen from the Ariane 4 gas generator). That does still not automatically increase the pressure, if that is what you want.

Depends on what you want: Generally, remember the ideal gas law, you would prefer the gas hot to let it do work by a pressure drop.

 

[Gerdih]

Edited the first post, I wanted to mean that the idea is to achieve the maximum pressure we can, doesnt matter which gas we estorage or the way we use. Only that the device must not be giant, thanks for the info!

 

[boogabooga]

Could you just use the high temp. decomposition products (H2O and O2) directly?

 

[MaverickSawyer]

I think that the H2O2 is probably the best bet... However, I don't have much knowledge in this area, so I'm not the best source of info! :lol:

I think that you could use 30% concentration: it's relatively common and more stable than the 90+% concentration used for aerospace projects. Plus, it has a lot of water in it already, which helps keep the temps down and provides a boost in the form of steam. Again, don't quote me on this.

 

[Gerdih]

Could you just use the high temp. decomposition products (H2 and O2) directly?

Yes, thats the second idea, not sure if I explained it well on the first post. But that way we still have some energy that we could use to compress atmospheric air for example. On the other hand, could we use the heat to direclty compress the result gasses of the reaction easily? Using a kind of nozzle for example to reduce the volume, according to the ideal gas law it should increasse the pressure but dont know if that process is better

 

[boogabooga]

It takes work (energy) to compress a gas. You are proposing to use energy from the system to compress itself to lower the volume, and higher pressure. Compression raises the temperature. Sorry, that energy needs to come from somewhere. You are proposing a violation of the Second Law of Thermodynamics.

 

[Gerdih]

It takes work (energy) to compress a gas. You are proposing to use energy from the system to compress itself to lower the volume, and higher pressure. Compression raises the temperature. Sorry, that energy needs to come from somewhere. You are proposing a violation of the Second Law of Thermodynamics.

Oups yeah, I see your point there. Too many finals and coffe recently, my brain needs to rest!

 

[Urwumpe]

Oups yeah, I see your point there. Too many finals and coffe recently, my brain needs to rest!

You could still use the pressure of the gas generator for compressing a cylinder of cleaner gas

 

[francisdrake]

Maybe I misunderstood the question, but if you need a high pressure fluid to activate penumatics or hydraulics, wouldn't it be the easiest way to use a pump?
The only downside is the pump needs external energy to run, but this is not prohibited in the request.

 

[tori]

What kind of pressure are we talking about here? kPa, MPa, more?

What volume do you need and how long do you need to sustain it? Liters, cubic meters, working for a fraction of a second or minutes?

Does it need to be restartable or is it a one-time deal?

If you need a single-use MPa-range gas generator that needs to run for a few seconds providing say 0.1 m³ of high pressure gas in the compact size you specified then a very reliable and inexpensive solution exists in the form of a pyrotechnic charge (similar to a solid rocket motor).