---- David Beierl <dbeierl@ATTGLOBAL.NET> wrote:
 Which always leads me to wonder
> what happened to the ROVAC
> system.
> <http://books.google.com/books?id=WwEAAAAAMBAJ&pg=PA84&lpg=PA84&dq=rovac+air+conditioner&source=bl&ots=VvTiK97nzA&sig=2MCLGpTq0lnWCCKsLv6nDvNvFmQ&hl=en&ei=DX0QTOeRCcP38AaVwOH-BQ&sa=X&oi=book_result&ct=result&resnum=7&ved=0CDUQ6AEwBg#v=onepage&q=rovac%20air%20conditioner&f=true>

Well, David -- that article is 35 years old.  I followed the description in detail.  I keep thinking something like, "No free lunch."  Does air really have that much thermal capacity to provide that much cooling effect from compression and expansion?  Especially as the article describes the system as recouping much of the energy used for compression.  I wonder.  Of course, I haven't done any calculations, and would have to go back to some old books to be able to do so, after so many years.

On a much simpler (and only marginally effective) note, back in the day, there were swamp coolers to hang on cars.  A metal cylinder with some sort of evaporative surface inside and a grill to catch air, with a snorkel to direct air into the passenger space, was hung on the car window.  No meaningful energy expenditure occurred (some nominal gas mileage effect from the drag), and relatively cool air blew onto the car's occupants.  My brother put in ice once, which set off my Dad's fiscal alert system, and resulted in a lecture about economy (said brother had bought the ice, probably a dime's worth at the roadside service stop).

Ain't life odd?

David McNeely