While this is a nice reference for thermal decomposition of LiAlH4, it is for a low pressure. The decomposition will be different in a small closed volume as the pressure goes into the range of 50-200 bar. Other reversible hydrides saturate at about 30 bar. It is valuable to determine the max pressure released in a closed volume vs. temp for this material. The MFMP experiment confirmed that in first stage decomposition the pressure reached in the range of 30 bar. After that the data is not reliable for 2 reasons. First, there appeared to be a problem with the pressure sensor producing huge output variation of hundreds of PSI - that is just not correct. Second, at high temperatures (800C for example), hydrogen permeates that stainless readily. I think there is good evidence that the pressure will be high with full decomposition without a leak, perhaps in the 100 bar range. It is worth additional experiments and data taking, all of which will require good seal technology.
MFMP is beginning to get feedback from Dr. Parkhomov. Bob Higgins On Sun, Jan 4, 2015 at 8:01 AM, Bob Cook <frobertc...@hotmail.com> wrote: > CB Sites-- > > Check out the following for LiAlH4 decomposition: > > http://rspa.royalsocietypublishing.org/content/royprsa/211/1106/335.full.pdf > > Mark Jurich provided a nice reference list on the properties of LiAlH4 > yesterday, Saturday, January 03, 2015 11:56 AM nere on Vortex-l. The one > cited above is from his list. > > > Bob > > ----- Original Message ----- > *From:* CB Sites <cbsit...@gmail.com> > *To:* vortex-l <vortex-l@eskimo.com> > *Sent:* Saturday, January 03, 2015 10:04 PM > *Subject:* Re: [Vo]:Ceramic-to-metal hermetic bonding > > You know Axil, maybe they are based on the internal pressure estimates > I've read here. When the MFMP finally had the pressure transducer > stabilized they had 100psi which decreased linearly to 0 after power off. > A redo of that experiment would be worth doing just to get the kinks out of > the pressure gauge. Then you might see the disassociation of LiAlH4 to Li > and H in the pressure change. As another vortexian mentioned, I don't > think that has ever been published. So knowing PV=nRT the value 'n' can be > deduced or the expected value of P can be deduced with temp as some have > already done. Given a temperature goal, and perhaps knowing the strength > of the contain these can be designed into the experiment. So instead of > worrying about seals, just design a tube that can contain hydrogen gas at > 1400C and be loaded with fuel under a vacuum to maintain purity of the > reactants. > > > On Sat, Jan 3, 2015 at 11:29 PM, Axil Axil <janap...@gmail.com> wrote: > >> I think that MFMP is concerned about melting or exploding the core. >> >> On Sat, Jan 3, 2015 at 11:07 PM, CB Sites <cbsit...@gmail.com> wrote: >> >>> I agree with you Bob. Getting a good seal will be the challenge of this >>> experiment. I've seen a few electron micrographs of hydrogen is Si and >>> other metals and it is amazing how deep H will migrate into a lattice. >>> Jones Benne points to the S-bond.com. It will take something more than >>> that to seal this structure at the high temps, high pressure and >>> embrittlement from hydrogen gas in this experiment. Knowing the pressure >>> and core temp is a noble cause, but until replication is done, do we know >>> enough about the phenomena to pursue those experiments? >>> >>> >>> On Sat, Jan 3, 2015 at 6:40 PM, Bob Cook <frobertc...@hotmail.com> >>> wrote: >>> >>>> Jones-- >>>> >>>> Unless the thermal expansion of the alumina body is matched to the >>>> expansion of the Stainless Steel sleeve, it will be very hard to maintain a >>>> seal. The thermal stresses will become very high at the interface of the >>>> two materials. I think that the pressure changes seen in the recent MFMP >>>> test were due to thermal expansion acoustic emissions upon each increase in >>>> temperature. This emission caused the pressure sensor to spike. A sonic >>>> acoustic emission monitor would be valuable to deduce where the strain is >>>> and its intensity as a function of heating, if good sealing of the >>>> connection is necessary. I am not sure the objectives of the test required >>>> such sealing and pressure containment. >>>> >>>> (Acoustic emission monitoring is an old technique to look for micro >>>> cracking in fission reactor equipment that happens during thermal >>>> transients. Its quite sensitive and has/had been resisted by reactor >>>> vessel manufacturers, because it was so good for identifying defects >>>> in their forgings that other wise might not be discovered.) >>>> >>>> Bob >>>> >>>> ----- Original Message ----- >>>> *From:* Jones Beene <jone...@pacbell.net> >>>> *To:* vortex-l@eskimo.com >>>> *Sent:* Saturday, January 03, 2015 1:49 PM >>>> *Subject:* [Vo]:Ceramic-to-metal hermetic bonding >>>> >>>> It is possible to bond alumina, such as a modified dogbone reactor >>>> directly to stainless tubing, using the proprietary S-bond alloy : >>>> >>>> >>>> >>>> http://www.s-bond.com/blog/2011/04/04/ceramic-metal-bonding-part-one/ >>>> >>>> >>>> >>>> The advantage would be allowing a permanent fill port for hydrogen, >>>> along with a pressure gauge, and other feed-thru accommodations which are >>>> more easily ported into metal then into ceramic. >>>> >>>> >>>> >>>> The design problem would be in keeping this metal part of the reactor >>>> cooler than the rest of the reactor – and the simple solution for that is >>>> to add a long ceramic extension tube to the dogbone, which extension is not >>>> powered and it can be as long as the reactor itself with a decreasing >>>> temperature gradient, then to add the stainless plumbing to the far end of >>>> the ceramic extension tube using S-bond. This keeps the heated segment >>>> spatially removed from the stainless. There would be a hot-end and a >>>> cold-end, and the entire unit would be much longer. >>>> >>>> >>>> >>>> For any dogbone device to move towards commercialization, far more >>>> control must be implemented, including fuel availability and pressure – and >>>> this means adding hydrogen from a tank at a controlled pressure. A ceramic >>>> to metal bond is one way to do that. >>>> >>>> >>>> >>>> I am assuming that hydrogen is the only consumable, at least until >>>> testing from Parkhomov shows otherwise. >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>>> >>> >> >
