On Mon, 08 Oct 2007 18:08:51 -0700, Keith Hughes
wrote:

he whole exercise was to get a passive system. If you're going to add
a vacuum pump, then you just provide continuous evacuation on the
freshwater side, using a demister that drains into the freshwater pool,
to separate the water vapor from the non-condensables. But if you
accept the need for a pump, why use this rather byzantine approach at all?

The whole idea here seems ridiculous. This is nothing but a solar
still. Reducing the boiling point is not necessary. All the energy
absorbed, or nearly, will evaporate water. The limiting factor is the
energy input. There is no benefit to making a modest capacity still
thirty feet tall, and skinny. Make it short and fat and save material
and weight. Did anyone mention weight aloft and windage? The hot side
of the skinny job will be well cooled by the surrounding air.

Casady