[bigbear]

I hope I am posting this in the proper forum, if not, feel free to move it.

I am doing a feasibility study.    This is a generalized question.   The goal is, to use two or more reagents, or any mix of substances.... so as this mixture will convert to gas with preferably no energy input.   (does not need to be 100% gas, some substance can be left)   That's easy enough....

But next, after it converts to gas, I want to reverse the process and convert it all back to its non gaseous state (liquid or solid)   Again, using very little energy (on a relative basis, vs. the substance mass).   If required, it would be OK to add a reagent to convert back to the non gaseous state, assuming it was an abundant very low cost substance.    This process would need to be repeated over and over without having to change the base substances.    This continued conversion should happen relatively fast, less than  a few minutes.   

Is there a mix of reagents which would meet this criteria?  TYIA   

   

[Arkcon]

What you want, almost certainly, violates the most basic laws of thermodynamics.  If you don't want to add heat energy, you can achieve the effects you want, but instead must use energy to greatly change the pressure.  If you can be a less generalized in your question, and give some details on the feasibility study, someone may be able to help you more.

[bigbear]

Arkcon....  I thought this was possibly infringing on the law of thermodynamics.. so I will be more specific, hopefully this will help.

Lets assume one cubic meter of a collapsible vessel, such as a balloon.  (it would not be an actual balllon, but for sake of simplicity)   The balloon sits inside a tank of 20ft deep water.   When the balloon is full of gas, it rises to the top of the water.  Then, the reversing process occurs, the substances return to their non gaseous state, the balloon shrinks and falls to the bottom of the tank.   

I realize for this reaction to occur, something additional must be introduced for one of the state changes,  i.e. either energy or a new reagent.   The goal was to find the most cost effective means to achieve this continuous state change.   

[Arkcon]

Oh, something like this:

http://hardware.slashdot.org/article.pl?sid=08/02/12/0259228

[bigbear]

No, the submarine has the benefits of variance in the ocean temps.... In my example, I don't have that luxury, such changes must be introduced...