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  • #31
    Re: Adsorbed Natural Gas Technology

    Thanks Curtis

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    • #32
      Re: Adsorbed Natural Gas Technology

      I have heard that the NG going into the "charcoal" tank has to be extremely clean. Any contaminates in the NG and the charcoal will NOT "absorb" the NG. Once the charcoal is contaminated, I wonder if you can clean it or do you have to throw the tank away? Also, the price of NG would increase, because it would require that the contaminates be removed prior to putting them into the tank.

      It is great technology, I wonder how it would work with hydrogen?
      Jared.
      Mountain Green, Utah
      2003 CNG Cavalier
      2003 CNG Silverado 2500HD

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      • #33
        Re: Adsorbed Natural Gas Technology

        Originally posted by Highmarker View Post
        I have heard that the NG going into the "charcoal" tank has to be extremely clean. Any contaminates in the NG and the charcoal will NOT "absorb" the NG. Once the charcoal is contaminated, I wonder if you can clean it or do you have to throw the tank away? Also, the price of NG would increase, because it would require that the contaminates be removed prior to putting them into the tank.

        It is great technology, I wonder how it would work with hydrogen?
        Similar research is being done with Hydrogen, though instead of a Charcoal matrix (which wouldnt' really bond with the hydrogen), it is using pellets of a metal hydride to bond the hydrogen.
        1997 Factory Crown Victoria w/ extended tanks ~~ Clunkerized!
        2000 Bi-Fuel Expedition --> ~~ Sold ~~ <--

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        • #34
          Re: Adsorbed Natural Gas Technology

          Originally posted by Highmarker View Post
          I have heard that the NG going into the "charcoal" tank has to be extremely clean. Any contaminates in the NG and the charcoal will NOT "absorb" the NG. Once the charcoal is contaminated, I wonder if you can clean it or do you have to throw the tank away? Also, the price of NG would increase, because it would require that the contaminates be removed prior to putting them into the tank.


          It is great technology, I wonder how it would work with hydrogen?

          Jared;

          I'm curious. Where did you hear that, and what did the source mean by 'impurities'? If your source means that it has to be particularly dry, that would be reasonable. If your source is concerned about other aliphatic molecules (propane, ethane, etc.), I am not so sure, and if the person is referring to H2, N2, O2, or something like NOx, my BSIL will start flashing immediately. Ozone would be another matter altogether.

          If the contaminants are adsorbed gases, they should be removeable via hard vaccuum and either heat or ablutive gaseous displacement (like keeping very high grade ethanol from absorbing water by bleeding nitrogen through it). Is the problem due to some sort of chemical activity?

          I am crunching numbers while boning up on gas dynamics (always a riveting read) and dislocation density to describe a model of how adsorption would work, and this might shed a little more light. Thanks!

          Andy-Paul
          Last edited by Andy-Paul; 07-03-2008, 09:34 PM. Reason: additional data

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          • #35
            Re: Adsorbed Natural Gas Technology

            sOME INTERESTING INFO ON THE ang SUBJECT:

            http://www.ecofuel-asia-tour.com/technik.0.html?&L=2

            BASF BASOSTOR

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            • #36
              Re: Adsorbed Natural Gas Technology

              Originally posted by CanAm View Post
              sOME INTERESTING INFO ON THE ang SUBJECT:

              http://www.ecofuel-asia-tour.com/technik.0.html?&L=2

              BASF BASOSTOR
              If they would start selling those large surface area granules, I would be very happy with a 30% increase in my fuel capacity by adding them to my Civic GX tanks!
              Adrian

              Navy 2008 Civic GX (wife's)
              Silver 2012 Toyota Prius
              Grey 2012 Civic Natural Gas (mine)

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              • #37
                Re: Adsorbed Natural Gas Technology

                Well, simply adding them to your tank would be good and bad. Basically, on a slow fill, it would work great, as long as the slow filling system kept the high pressure on for long enough for the adsorbant to 'soak up' the methane. On a fast fill, it would seriously decrease the amount of gas you could put in, because the adsorbant would displace the sapce the gas usually occupies. Basically, your tank would fill up to 3600# extremely quickly, as the actual area to hold the gas is considerably less. The pressure would then drop off over time as the gas is adsorbed. I feel this is going to be the biggest hurdle with any adsorbed technology, the difference in filling techniques.

                You also need some sort of difusing screen in the tank to let the gas out, and NOT the adsorbant, which is small pellets tha could fit through a normal shutoff valve.. that would be BAD for regulators downstream...
                1997 Factory Crown Victoria w/ extended tanks ~~ Clunkerized!
                2000 Bi-Fuel Expedition --> ~~ Sold ~~ <--

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                • #38
                  Re: Adsorbed Natural Gas Technology

                  Idarusskie;

                  Here ya go.

                  A methane molecule is tetrahedral. All four points have H atoms on them, so orientation is irrelevant. The distance between H atoms (tetrahedron’s corners) is 0.1749 nm, so this can be used as a rough number for the length of one side of the CH4 molecule. In a mono-molecular system, CH4 has STP density of 0.00068 g/cc or molecular energy levels makes CH4 unlikely to come together at normal conditions. To improve CH4 density without going to extremes of temperature and pressure, carbon makes a good buffer, for at least three reasons. First, CH4 is weakly attracted to a carbon surface (van der Waals). Second, carbon in a low-pressure formation is quite porous. Third, it is cheap: any very finely ground cellulose will work.

                  Take a kitchen sponge (3.75” x 5” x 0.5”—with a scrubby side). Squeezed out, it weighs about 30g. Stick it in a bowl of water, squeeze it, release, let it fill and reweigh. It weighs around 130g. This is adsorption. The water is stored by the sponge so you can carry it around, but neither the water nor the sponge has chemically changed.

                  Carbon atoms combined in a low pressure formation have a simple hexagonal matrix with experimental STP density of 2.25g/cc. Chemical reduction to a C matrix from cellulose removes gaseous compounds from the system. The gases dislodge carbon atoms to leave big nano-porous tunnels and small nano-pores behind. Many of these are connected to the matrix surface.

                  From the view of an electron microscope, the matrix looks like a coral reef—tunnels and holes in the range of, say, 50-500 nanometers across. Now pretend you can touch it. It feels rough because small groups of carbon atoms are missing from the surface of the reef, providing nano-pores. The pores would be substantially smaller, from about 0.5-5.0 nm across, but they line tunnels or holes large enough to let CH4 molecules bounce off the sides and keep drifting until each finds a nano-pore.

                  Assume that CH4 will rotate around its central C atom to describe a sphere of diameter 0.1749 nm. We can then assign the CH4 a volume of 0.022 cubic nm (cnm) based on precession. What size pore would hold a CH4 molecule against the carbon without its being bothered by other CH4 molecules drifting by?

                  A carbon matrix will hold CH4 based not on volume of C (like tank volume) but on the surface area of the matrix within a tank. A single C-C bond is 0.174 nanometers across. The C atom itself is 0.071 nm diameter. A group of six carbons has a diameter of 0.6 nm, and there are 14 atoms in a crystal cell (one in the middle of each hex). Given about 28 hexagon units in a cnm, count 392 C atoms per cnm. Then, there are about 10to the 21st cnm per milliliter (or cc). If the carbon atoms were perfectly stacked in simple hex, there would be 3.92 X 10 to the 23 C atoms in a cc. That works out to about 0.65 moles of material weighing 7.8 g.

                  At 2.25 g/cc, the experimental value is only about 28% of the theoretical value because of quantum forces, even before reducing the cellulose to charcoal and blasting them with hot gasses. The difference is due to dislocation—or atoms that just had too much energy to stay in a lattice spot. If that empty spot is accessible, then the pore between the two closest remaining surface atoms is 0.548nm, opening a hole of volume 0.3429 sqnm, which would hold a CH4 molecule.

                  28% of theoretical value means that about 70% of the lattice positions are not filled. This means more surface area for the CH4s to park against, even before we have filled the lattice with big holes due to out-gassing. Once you combine the 70% dislocation rate of C with micro-tunnels, large nano-tunnels, and smaller nano-pores which are themselves larger than the single dislocation parking spots, the amount of storage space enlarges into the 100x and up range.

                  There’s a lot of hand-waving and SWAG here, but the overall picture isn’t too bad. CH4 packs in because the C is organized enough to hold individual molecules but not so well organized as to keep the CH4 out of its interior passages. The extra pressure used to force gas into the matrix at 500psi raises the number of atomic dislocations in the carbon matrix by a factor of 10000-1000000—more room for CH4. Also, as long range order breaks down—and it has, thanks to that out-gassing--the matrix breaks into grains which have boundary areas that will allow even more gas storage. The smaller the grain size, the lower the long-range order in this case, so the more CH4 you can stash.

                  For those of you with more knowledge in this direction than I have, please correct me. Also, did y'all know that the carat symbol [shift+6] will give you this?
                  Last edited by Andy-Paul; 07-13-2008, 11:25 AM. Reason: symbol conflict and misspelling

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                  • #39
                    Re: Adsorbed Natural Gas Technology

                    You also need some sort of difusing screen in the tank to let the gas out, and NOT the adsorbant, which is small pellets tha could fit through a normal shutoff valve.. that would be BAD for regulators downstream...[/QUOTE]

                    CraziFuzzy;

                    What would be the difference between what's happening at the end of the ANG tank and the end of the diesel combustion cycle? Both are particulate pollution issues, aren't they? Seat-of-the-pants suggestion: use a diesel filter--probably not Bosch/Bluetec, though...chemically reactive?

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                    • #40
                      Re: Adsorbed Natural Gas Technology

                      Originally posted by Andy-Paul View Post
                      CraziFuzzy;

                      What would be the difference between what's happening at the end of the ANG tank and the end of the diesel combustion cycle? Both are particulate pollution issues, aren't they? Seat-of-the-pants suggestion: use a diesel filter--probably not Bosch/Bluetec, though...chemically reactive?

                      I was not refering to particulate pollution.. dang, why does everyone here think CNG is about the environment.. i say screw the environment.. i'm all about my pocketbook.. anyway, back on topic, I was simply stating that you can't just add this stuff to your tank, and expect more range.. you ahve to have something to HOLD it in the tank. Some sory of filter plate/diffusino screen that has holes smaller than the adsorbant pellet size is all that would be required.

                      The Bad i was talking about was if you tried passing pellets of charcoal through your natural gas system.
                      1997 Factory Crown Victoria w/ extended tanks ~~ Clunkerized!
                      2000 Bi-Fuel Expedition --> ~~ Sold ~~ <--

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                      • #41
                        Re: Adsorbed Natural Gas Technology

                        CraziFuzzy;

                        Sorry 'bout that. I wasn't talking environmentalism, either. I was just being a wiseacre at pointing out how a tankful of carbon particles could be kept from leaking carbon into the fuel stream. It is similar technology to that being currently used to collect post-combustion particles from a diesel system, especially given the amount of carbon in both waste streams.

                        Andy-Paul
                        Last edited by Andy-Paul; 07-14-2008, 10:41 AM. Reason: misplaced preposition and wrong conjunction

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                        • #42
                          Re: Adsorbed Natural Gas Technology

                          Thanks that is a lot to chew on.

                          I should think that one would keep the pressure in the tank as much as possible. The engine needs maybe 1-2 PSI of natural gas to run( wild guess). I do not know if the carbon dust would cause problems or not. I would think that they would just burn up in the cylinder like carbon deposits on spark plugs. Still you do not want to replace your storage matrix every day.

                          Any guess on the physical size of the tank?

                          I think a fast fill system using LNG could fill the carbon fairly fast. Weather you can make LNG cheaply is another matter.

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                          • #43
                            Re: Adsorbed Natural Gas Technology

                            Idarusskie;

                            If the adsorption medium's surface area is sufficient, the tank should be the same size and shape as a standard gasoline tank while holding *at least* as much energy. I'll bet a box of crullers from Daylight Doughnuts that the next generation ANG tank from the Mizzou crowd will be able to beat petroleum's energy storage density, though. Those cats are sharp.

                            I don't know if a carbon-filled tank would require LNG, or could even use it--that's a big temperature differential for the adsorption matrix to handle unless it's ceramic. Also, I am thinking that engine pressure for straight CNG is around 300 PSI, hence the need for a stronger head on the refit. That raises some very interesting questions about how much ANG tank pressure can be lost before the engine can no longer pull fuel, though. I'll check with CNGHal.

                            Also, I think fast-fueling ANG would require a different style filler from the traditional tank & nozzle.

                            As stated earlier, I am reading in gas dynamics, and the way to get more in faster is to keep the flow as linear as possible (minimize back pressure and eddy currents). This is seat of the pants, but I think fast-fueling an ANG tank would work best with either a fuel nozzle that looks like a big serial data plug, loading the gas in discrete jets, or an in-tank diffuser doing the same thing. To assist the lading, a back-pressure sensor at the mouth of each jet/diffusor opening would raise or lower individual jet pressures as the adsorption storage dynamics dictate.

                            Maybe overcomplicating? I'll keep chewing on that one. Glad the numbers were helpful.

                            Andy-Paul
                            Last edited by Andy-Paul; 07-14-2008, 08:47 PM. Reason: one more piece of data

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                            • #44
                              Re: Adsorbed Natural Gas Technology

                              hehe, yeah andy, I'd say you're overcomplicating. Basically all that needs to be done is apply a pressure to the medium, and maintain it. The media will adsorb the CNG at higher pressures, and release it at lower pressures. This is not instant though, which is why fast filling would not be as effective.

                              As for gas pressure at the engine, it could work as low as atmospheric, as long as the injector system is designed for whatever pressure you've got. My conversion system DOES work at nearly atmospheric pressures under normal operation, feeding into the intake header (which is at a vacuum), though most factory cars i believe use the fuel rail at around 100#.
                              1997 Factory Crown Victoria w/ extended tanks ~~ Clunkerized!
                              2000 Bi-Fuel Expedition --> ~~ Sold ~~ <--

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                              • #45
                                Re: Adsorbed Natural Gas Technology

                                I understand why you are saying that, but let me give you a little something to chew on here.

                                If a big old gullywasher dumps 10 inches of rain on parched clay in two hours, the top of the clay gets wet but you don't get squoodly below that very top layer--penetration falls off exponentially. But if that 10 inches comes down over 24-48 hours with an overcast sky, the clay gets wet much deeper.

                                The question for me is whether we can get better surface penetration with a single jet--like shooting 3600psi into an unmediated CNG tank--or if we could get more efficient fuel penetration through multiple small streams hitting the adsorption media at multiple points in order to improve gaseous dispersal into the crevasses (crevices?).

                                I ask this knowing from experience that it makes a big difference how the water gets poured into a ceramic batch mixer. If you pour in a single slug the time spent wetting the mix is much different than if you use a nozzle that sprays in the same amount as a mist--sometimes one way is faster, sometimes the other, depending upon surface area of the dry mix, porosity of the particles, etc, etc. We do want a constant pressure at the end of the run, of course, but we want that constant pressure as soon as possible in order to avoid revisiting the whole slow-fill/fast-fill technical hurdle again.

                                Now that I have said all that, you may be 100% right!

                                --which is why I love research engineering. Assumptions get skewered, ideas turn out to be completely bass-ackwards, and the scariest place to be at the end of a new experiment is where theory and practice have just matched up--that's when something is usually incredibly wrong or (once in a long while) you have gotten unbelievably lucky. So: unless yer packing the equations or some serious modelling software--more later, dude!

                                andy-paul
                                Last edited by Andy-Paul; 07-15-2008, 09:29 PM. Reason: spelling

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