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Passive thermal compression of LNG to make CNG

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  • Passive thermal compression of LNG to make CNG

    My lattest hair brain idea.

    I'm sure it has been tried before, Might not be too safe .

    Take a DOT cylinder at 0 psig, put in a measured amount of LNG that would not exceed the working pressure of the cylinder when the contents fully vaporize in the summer sun.

    Room temp to 260 degrees below zero in a few minutes ( metal usually doesn't like this ) and then slow rise to room temp and 4,000 psi in a couple of days.

    Would this be abuse of the cylinder or be outside of it's design conditions ?
    Last edited by Lakewood90712; 10-04-2011, 09:28 PM. Reason: added

  • #2
    Re: Passive thermal compression of LNG to make CNG

    That would be nasty for testing conditions. I would think that the cylinder would need to go through the drop test and/or impact testing while at or near the cryogenic temperatures. its an interesting notion and I can see what you are thinking of, just too many considerations to manage to be of practical use.
    '11 Fusion Bi Fuel & FMQ2-36 VRA
    (Former owner '09 Civic GX)


    • #3
      Re: Passive thermal compression of LNG to make CNG

      I think raskell's thinking is spot on - The design requirements and testing for the CNG tank that can handle the temperatures present a major effort.

      With that said, maybe your idea has some value in a slightly different configuration. A dual tank system (LNG, CNG) might be possible where the vaporized natural gas that does not get used imediately as fuel could be stored in a CNG tank - maybe even a CNG tank that is presurized below 3000 PSI (could be a cheaper tank). I guess you would need to determine if you can come up with tank sizes and configurations that would result in less space being used or lower cost tanks.

      Sounds like an interesting science project requiring lots of time and probably significant costs should you decide to certify anythng new or novel.

      Best of luck there.


      • #4
        Re: Passive thermal compression of LNG to make CNG

        This would be for stationary use only, instead of a compressor.


        • #5
          Making a gallon of LNG in your garage at home:


          (short version - 5 min)

          (full length - 45min)

          (search terms liberty tate cryogenic vaporizer small-scale)



          • #6
            t boone was doing this at some of his lng stations they are using a large vaporizer and just pump lng in one end and presto out the other end comes cng