Are there any Socket F/940 evaporator blocks available?

[apt403]

Yeah, a 1 hp rotary would be a good estimate, depending on how cold you want to go and what you use for refrigerant. If you don't want something that sounds like a V8 in your case, you could use hermetic or semi-hermetic compressors, but those are more expensive, especially for the kind of power you'd need.

You will need SOME tools that would carry over to phase building, but if you wanted a chiller you could take a standard window AC unit and slightly modify it for your purposes. You'd essentially just have to strip it down, and put it into another housing in such a way that you would have the evaporator sitting in a tank of ethylene glycol or propylene glycol mixed with water.

Or a plate HX with refrigerant running through one side and the water/anti-freeze through the other. That would save on size, but you'd be looking at some minor modifications to the AC unit. Namely vac'ing the refrigerant, brazing on the plate HX in place of the stock evaporator, and recharging the system.

Or you could use a TEC cooler to chill the water, that's even easier. Although you're looking at temps that will be higher than the phase setup, you massively cut down on complexity and cost.