Is it possible to make an AC chiller using normal PVC and a vacuum pump?

Question

I was reading about chillers and refrigerants and thought that if there is a strong enough vacuum it could be done. I’m seeking the advice of experts here. I think an evaporation process in the evaporator part of the unit might be achieved if there is a strong enough vacuum to drop the boiling level to a lower temperature. The refrigerant say normal water may be pulled into the evaporator through an expansion valve o*****e by the vacuum and begin to evaporate. There would be no condenser as the water produce hopefully will be distilled water that I can use in the house. Or the return piping would be long enough to allow the water to condense and be reused again in a closed cycle?

Answer 1

I hate to burst your bubble, but this is a case where a little knowledge is a dangerous thing.  In theory, what you propose is possible, but you would have to pull a deep vacuum down below 100 microns to get the water to boil at < 40 degrees.  The commercially available vacuum pumps in supply houses can reach those levels - but (there's always a "but") - they don't pump the volume you would need to achieve effective cooling of any area the size of a house or apartment.  It would also cost way more than a unit using common refrigerants.  If it were practical, the global HVAC & Refrigeration industry would not have spent billions in research coming up with replacements for chlorine-bearing refrigerants over the past few years.

Answer 2

Looks like you would need a vacuum of 25torr to get the water to boil at about  20C(68F).  You want the water to boil at 40 -55F but let’s continue.

25 Torr is .9843 Hg   Normal atmospheric pressure is 760 Torr

For $350 you can get a vacuum pump that will do 26” or 660 Torr

You need 25 Torr, do you see where this is going?

You need something called a 2 stage Liquid ring vacuum pump to get to 25 Torr.

I think you might be able to fit the system into a 2-3 car garage, but the neighbors will complain about the noise and your electric bill would be huge.