X-Message-Number: 7675 Date: Mon, 10 Feb 1997 14:34:13 -0500 From: (Ken) Subject: Re: Technology Disclosure Paul, I just saw your idea for an improved Dewar vault, and I love it! I particularly like the beautiful negative feedback mechanism built into the design (i.e. increased ambient temperature->slightly increased boiloff rate -> increaed cooling of the external surfaces -> resistance to further increase in boiloff rate). So. how to improve it? One critical observation: you're reaching the point where the major thermal conductors into the system are the air and nitrogen vapors themselves. Design accordingly- insulate the walls and floor of your silo. Hopefully you're not using bare concrete for the floor; you should at least have a raised wooden platform packed with foam to really take advantage of this design. Or, if you really want to do it 'right', consider doing for the air/nitrogen gas what you're already doing for the metal Dewar walls: reduce the thermal gradient by lengthening the path out of your system. May I suggest piping the escaping gas through something, e.g. a garden hose packed in some insulation? If 85% of your current losses are through the metal inner dewar wall, I'd actually be surprised if you didn't cut your LN2 boiloff in half with this overall approach. (What will the economics of cryonics storage look like if boiloff gets cut down to the 3 or 4 l/day neighborhood?) Good luck! -Ken Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=7675