This pump would be very similar to a scroll compressor but rather than having a second moving scroll it would use drops of ferrofluid.
A rotor having two or more magnets attached to it radially would pull the drops of ferrofluid around a spiralling tube. As the drops approach the center of the pump, the space between them decreases compressing the gas in those spaces. The drops, along with the now compressed gas, exit at the center of the spiral.
I'm not sure how you could get the ferrofluid back to the low pressure side but if someone can figure that out this might actually work.
I was hoping that this sort of a pump could be used in a vacuum system. Ferrofluid sealed rotary feedthroughs are used in vacuum systems so there are ferrofluids with low enough vapor pressures to work. Also, the Sprengel pump, one of the first high vacuum pumps, used mercury drops pulled down a capillary tube by gravity to remove the air trapped between the drops. this pump would be similar using magnets and ferrofluid instead of gravity and mercury.-- RichardT, Nov 11 2010 scroll compressors http://en.wikipedia...i/Scroll_compressorWikipedia's article [RichardT, Nov 11 2010] sprengel pump http://en.wikipedia.../wiki/Sprengel_pumpWikipedia's article [RichardT, Nov 11 2010] ferrofluid pumping charachteristics http://cat.inist.fr...heN&cpsidt=15764168simple two piston ferrofluid pump reaches 5 kpa (~1/20th of an atmosphere) [RichardT, Nov 11 2010] Ferrofluids are cool. Nice to see an idea that might actually work, from someone who has clearly half-thought it through ! +-- csea, Nov 11 2010 Use two spirals on top of each other, wound in opposite directions, joined at the centre and at the outermost edge, and separated by an insulating disc. The gas is compressed in one direction and allowed to expand in the other, and we've got a heat pump, which pumps heat from one spiral to the other.
Reverse the direction of rotation, and it pumps heat back the other way instead.-- Wrongfellow, Nov 11 2010 random, halfbakery