Posts by gjn

Quote from Longview

Seeing the issues that continue with Nichrome / Kanthal wired ceramic cores. I suggest we try to design and build a more durable reactor that allows replacement and/or renovation of the core, with relatively little maintenance on the "furnace" portion. At this stage of replications it may be time, since I see a lot of effort in building the heating elements and whole reactors over and over. Combined with the great difficulty in changing the formulation within the reactor core itself.

Here is a preliminary vision of how both issues might be addressed. Using quartz halogen lamps (they are used in movie projectors and in ceramic cooktop stoves today, as well as in lighting). An array of such lamps could surround concentrically a central reactor core made of aluminum oxide (perhaps with a layer of refractory pigment such as carbon or zirconium carbide to enhance absorption of thermal photons.... or the central core could be essentially transparent (pure optical apphire for example, big money I'm sure) to a broad range of wavelengths, to increase transmission to the internal contents.

Clearly such lamp filaments can be driven to much higher heat than Nichrome / Kanthal. Actually about 3 times the temperature. Especially with the halogen+xenon gases in the bulb, which prevent the filament from sublimating, allow much higher color temperature exceeding 4000 K with long life, or at lower temperatures (read more IR) with very long life. The latter IR rich bulbs would best be replacement types for a ceramic cooktop stove-- in halogen bulbs the content of halogen is changed depending on the tungsten filament operating temperatures.

To direct the radiant energy toward the central core, I suggest initially white, temperature tolerant ceramic, such as pyroceram surrounding the circle of lamps. However, the lack of strong conductivity might be an issue there since the lamps themselves can only tolerate so much heat (this tolerance is far higher than ordinary light bulbs, but probably not above a dull red for the housing... just a guess). Another more ideal reflector might be a heat tolerant metal, either stainless or Inconel, either of which could be fan or liquid cooled. For optimum reflection, an idealized future version might have a rhodium or other precious metal coating facing the lamps and the core --- I recall that these coating are very rugged, heat and corrosion resistant, and I am fairly certain they are broad band. These reflective coatings have been seen in the xenon discharge lamps used on larger theatre projectors and in heliocopter search lights. Such a coating is fairly thin (microns), so not as expensive as one might imagine.

So, a concentric to the core outer cylinder with a substantial number of quartz/halogen lamps arrayed around the inside. These lamps would be shielded so as not to heat one another, with the open side facing inward to the core. The lamps could be selected so that their length fully illuminated the full length of the "active" portion of the core. The core would extend beyond each end of the reactor furnace out to a distance to allow relatively cool connections, as we presently see in some of the replication designs. The outer portion, if designed and built well, should allow hundreds of 36 hour trials without so much as an occasional burned out bulb. My hope then would be that the excellent efforts of the replicators and other more exploratory efforts could be concentrated on the active material rather than on the "furnace" portion.

I welcome any and all comments. I hope we can successfully get somewhere with this idea.

Thanks,
Longview

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