Good question, I assume a filter of some sort, maybe include a vortex separator too. Cool the gas before the filter to make life easier. Filter is blown clean when you next refill.
On 25 January 2012 22:35, Chemical Engineer <cheme...@gmail.com> wrote: > How do you cycle hydrogen into/out of the reactor kernal without blowing > micro/nanopowder out of the reactor into the hydrogen system? > > I agree that a type of fluidized bed of micro/nano powder might work well > if uniformly distributed > > > On Wed, Jan 25, 2012 at 4:56 PM, Robert Lynn < > robert.gulliver.l...@gmail.com> wrote: > >> Hydrogen is amazingly good for heat transfer. Rossi and Defkalion are >> both using H2 of 2.5-5MPa, and at 600°C that will have density of about >> 0.7kg/m³ or greater. At that density 4µm nickel powder particles (As >> defkalion are specifying) will need a hydrogen flow velocity of about >> 0.5m/s to pick it up against the force of gravity (from bernoulli's >> equation). >> >> Please Note that the following calculations are very basic, and not that >> accurate, but give some indication about the size of flow speeds in the >> reactor. >> >> If the centre of the reactor is 600°C and the walls are 350°C then there >> is about 0.2kg/m³ hydrogen density difference between them, (about 2N/m³ in >> earths gravitational field). >> >> A reactor height of 50mm with that density difference would give about >> 2x0.05= 0.1Pa of driving force, and that pressure (from bernoullis equation >> again with 0.7kg/m³ density) would be equal to the dynamic pressure of >> hydrogen flowing at about 0.5m/s. >> >> So the powder is probably almost being picked up and circulated by the >> hydrogen. If the reactor was (taller) then the circulation of hydrogen >> would get faster and the powder would almost certainly start to get slowly >> blown around making a fountain in the hot middle of the reactor that would >> fall down the colder walls, gradually circulating the powder around the >> reactor. Also if the powder was smaller diameter then it would take less >> H2 flow speed to lift it up. >> >> But even without the particles moving you can see that the hydrogen will >> circulate (convect) in the reactor, fountaining up in the hot middle and >> dropping down the cool sides. Any hot spots will also increase the flow >> speed of the hydrogen locally in that spot due to reduced hydrogen density. >> The overall circulation of hydrogen will work to even out the temperatures >> throughout the powder very quickly, and if you want to increase the flow >> speeds and heat transfer then it is useful to have a taller reactor to >> increase the driving pressure (like a thermosiphon). >> http://en.wikipedia.org/wiki/Thermosiphon >> >> If you are very worried then you could also use a mechanical shaker to >> move the powder around and limit formation of hot spots. >> >> >> >> On 25 January 2012 21:20, mårten Sundling <mar...@krteknik.com> wrote: >> >>> Hello >>> Thanks for a great number of input. >>> My concern have been that the powder might just sit there as a pile >>> Be badly avaliable to the h2 and get >>> so hot by the bad cooling that it melts, I'm BTW using micrometer >>> powders at the moment by rossis specs, but it sounds like I will use nano >>> powder.... >>> I thought that I might overcome those hurdles by using a conductive >>> porous substrate, but that might not be the case then. >>> What's your opinion about using acetylene and nickel instead of >>> nickel,carbon,h2 a idea that is floating around.. >>> Marten >>> >>> Skickat från min HTC >>> >>> ----- Reply message ----- >>> Från: "Robert Lynn" <robert.gulliver.l...@gmail.com> >>> Till: <vortex-l@eskimo.com> >>> Rubrik: [Vo]:Nickel honeycomb ? >>> Datum: ons, jan 25, 2012 22:00 >>> >>> >>> I think are a many potential downsides to using bulk material substrates >>> (foams, foils, wires) with nickel coatings. >>> - you might get large and non-homogenous transient temperature changes >>> throughout the reactor and this could lead to deformation and even breakup >>> of large continuous scaffolds. >>> - it prevents transport of powder throughout the reactor (which may be >>> important for continuous operation in terms of subjecting the nickel to >>> varying temperatures or physical impacts to create hydrogen flux through >>> the nickel surface) >>> - a foil type substrate may constrain or otherwise limit convective flow >>> of hydrogen (particularly if there is thermal deformation of the >>> substrate), allowing hot-spots to form and creating worse >>> temperature inhomogeneities throughout the reactor. >>> - thermal expansion and material crystalline structure phase changes >>> caused by temperature change or hydrogen loading can lead to large >>> dimensional mismatches and stresses between substrate and nickel - leading >>> to the nickel coating flaking off etc, at which point why not just use >>> powder anyway? >>> - the processes by which you apply the nickel coating to the substrate >>> may have limitations and so not be optimal for creating the exact chemical >>> alloy makeup and surface topologies required for best LENR performance. >>> - making nano-powder will almost certainly be cheaper than any plating >>> procedure. >>> - harder to recycle substrate with nickel coating >>> - very easy to replace nickel powder in a reactor. >>> - one or more of the above problems will probably impose a lower >>> temperature limit on the process than the nickel powder would have by >>> itself. >>> >>> Hydrogen convection driven by buoyancy will likely slowly agitate and >>> transport nickel nano-particles throughout the reactor, with radiation at >>> high temperatures and physical contact of the blowing nickel particles with >>> the walls also enhancing heat transfer. >>> >>> That does not mean nickel on a substrate won't work, but it appears to >>> come with more potential problems, temperature limitations and higher >>> fabrication and running costs than nickel powder, with few if any benefits >>> that I can see. So unless you have other compelling reasons for a >>> substrate I think you may as well just stick with the nano powder. >>> >>> On 25 January 2012 19:28, <mar...@krteknik.com> wrote: >>> >>>> Hello guys >>>> I have a q, i have been reading all the posts about the problems with >>>> energy transfer, core melts and so on . >>>> Why not embed the nickel / catalyst mix in a honeycomb, or other >>>> structure that gets easy acess for both H2 and >>>> heat trasnfer to the walls of the tube ? >>>> >>>> >>>> Is there any practical method of doing this? >>>> I have thought about covering steel or other material with nickel as so >>>> many other people, but in my mind that decrease the surface >>>> too much, a fungi or honeycomb like structure would maybe work, but how >>>> to make one ? >>>> >>>> Any ideas ? >>>> >>>> >>>> Marten >>>> >>>> >>> >> >
