Yesterday evening we all tried to pump the fridge down.
Hard work. It all seemed to be working well - the pump
pumped, the pressure got lower and lower, the containers
all withstood the low pressures - but the blasted water
temperature didn't go down very impressively. 2 degrees
Celsius, maybe? That's hardly going to cool Ellen in
Death Valley, and we'll all have died of heat exhaustion.
We seemed to reach a pressure that we just couldn't
get lower than. Jonathan's PhD required a lot of playing
around with vacuums, so he has loads of experience with
them, thankfully. He says we just need to be really
careful about potential leaks, that seals can work really
well until you hit a particular pressure, when they
would start to leak, which means you just can't get
to a lower pressure.
I spend the day trying to make improvements. Everyone
is helping everyone else, and we're all beginning to
discuss other ways of trying to reduce the temperature.
For instance, chemical reactions that cause a big temperature
drop. Various reactions are used to make mixtures that
can freeze water (they've been used to make ice cream),
so Mike B is starting to think about of trying something
else ... we need all the help we can get!