FYI: Ryan was kind enough to reply back and stated that the Alumina Reactor Tube had over 0.1” tolerance in diameter inside the SiC Heating Element, so it appears that this expansion is not a concern. When I get some free time, I will try to formally go through the analysis and post it here, for future design work.
Mark Jurich From: Mark Jurich Sent: Wednesday, March 04, 2015 11:06 AM To: [email protected] Subject: [Vo]:Re: Rossi/Parkhomov reaction and the hydrogen anion Thanks for the info, Bob. For the last week, I have been concerned about the Elastic Expansion of the Reactor Tube due to the approximately 5000 psi pressure change that could occur. A back-of-the-envelope calculation revealed a 0.010” expansion. This is about an order of magnitude greater than the thermal expansion (If both tubes were the same Alumina Material, the thermal expansion would “track” each other and essentially cancel, but not the elastic expansion of the Reactor Tube due to the pressure.). If there wasn’t enough Free Tolerance for the Reactor Tube to “breathe” it would jam against the alumina heater tube surrounding it, creating small pressure points, possibly cracking both tubes. ... I’ll pass this note on to Ryan and perhaps he can rest my fears on this. - Mark Jurich From: Bob Higgins Sent: Wednesday, March 04, 2015 7:39 AM To: [email protected] Subject: Re: [Vo]:Re: Rossi/Parkhomov reaction and the hydrogen anion Ryan Hunt would better to ask this question. I believe the reactor tube in the Bang! experiment was from CoorsTek. The other dogbone alumina tubes were also from CoorsTek. They have an online store. It is the dogbone Lugano HotCat replica that has the heater coil wrapped around a second alumina "heater" tube and then overmolded with the finned convection surface. The design called for a heater tube ID of 7.95mm and a reactor tube OD of 6.35mm. I don't know what the actual tube measurements were. However, the Bang! experiment did not use the dogbone as the tube furnace for the experiment. Bob Greenyer had gotten some sample SiC tube heaters that could go to very high temperature. They tried molding one into a dogbone, but it was too fragile and just shattered during the molding process. The closed-one-end reactor tube was slipped into the SiC tube heater with no convection surface other than the bare SiC heater tube. I don't know what the clearance was for the SiC heater tube, but it was probably about 4-5mm in diameter. The SiC heater could go easily to 1500C, so there was no problem in getting the reactor tube as hot as they wanted. It would have been difficult to measure a real COP for that experiment. The thermocouple was attached to the reactor tube and it was also measured using the Williamson pyrometer. When the alumina tube exploded in the Bang! experiment, it completely shattered the SiC heater tube around it and that was the last sample. Future experiments will likely be in the dogbone. On Wed, Mar 4, 2015 at 8:16 AM, Mark Jurich <[email protected]> wrote: Bob, what was the Free Tolerance between the Reaction Tube OD and the Heater Tube ID in the MFMP Bang! Experiment? Who was the manufacturer of the alumina tubes? Thanks, Mark Jurich
