Ever leave a bottle of pop in the freezer to get cold, you take it out and does not look to be frozen, untill you pop the cap then it instantly freezes. Same theory. Liquid under pressure has a lower freezing point, when pressure is released, liquid will freeze.
I seem to vaguely recall that a fluid in motion has lower pressure, too.
Good point. the process of ebulition of disolved gases draws up energy and freezes the water.
If his pump is cavitating and then compressing gases , then when you open the tap the gasses bubble up which draws up energy and cools the water perhaps
I’ve also pulled an ice cube tray out of the freezer, the water in it still not frozen, and suddenly some cubes partially freeze, sometimes even generating little ice stalagmites or bumps upward...
Back in the 60s, I heard the term “triple point” for water - where it seemed to be liquid but wasn’t really any of the 3 states (liquid/solid/gas).
Pretty much that when water was at the freezing point but hadn’t solidified yet, just taping the container would set up enough vibration to release the last amount of “heat” and it would instantly crystalize.
More scientific explanation: https://www.thermal-engineering.org/what-is-triple-point-of-water-definition/
“Ever leave a bottle of pop in the freezer to get cold, you take it out and does not look to be frozen, untill you pop the cap then it instantly freezes. Same theory. Liquid under pressure has a lower freezing point, when pressure is released, liquid will freeze.”
Pressure has an insignificant effect on the freezing point.
This happened last evening to a bottle of wine my daughter brought over. She left it in the car for an hour and the cork popped!
The wine was like a slushy! But none of it spilled.
It was a very nice German Reissling.