I think estimations of the gas pressure inside the dogbone reactor tube at failure are probably substantial over-estimates. We don't really know how much volume was displaced by the Ni, so the volume estimate for the chamber is probably only accurate +100%/-50%. The volume of the system can and should be measured prior to start of the experiment. This can be done with a calibrated piston plumbed into the system. Decrease the volume by 1cc using the piston and see how the pressure changes.
Second, there is a hot volume and a cold volume, but only one pressure. Third, we don't know what is happening chemically inside the hot chamber. Sure there is decomposition, but there are probably also other hydride formations occurring at that pressure and temperature (note that there was added zirconium). Perhaps there was even ammonia formation which would reduce the pressure; and this could condense in the cold side. Fourth, the LiAlH4 weight added is probably only known +/- 20%. The summary is we really won't know what the pressure profile was in this experiment and we won't know until it is carefully measured. There is no real point to the wild speculation. It will just have to be measured. On Sun, Feb 8, 2015 at 9:47 AM, Jones Beene <[email protected]> wrote: > Yes, that is the good news - that the compression fitting works, and if > the problem relates to thermal stress, there is an easy way to fix that > also. > > To minimize thermal stress – the heater wire could be “feathered in” from > both ends, when it is wound so that there is an intermediate zone of heat > which is less than the fully wound wire, but greater than the unheated > zone. The idea is to spread out the areas of highest temperature > gradient, to reduce thermal stress. > > *From:* *Bob Higgins* <[email protected]> > > Ryan Hunt reports that the failure mode was NOT the compression fitting > giving way under pressure - the fitting remained intact. This experiment > was of the "easier Parkhomov" design, posted previously where the seal was > made with a compression fitting, in this case with the use of a soft > aluminum ferrule at the suggestion of Alan Goldwater. Alan's tests > suggested the compression fitting would hold and it did! \ >
