Well 3 phase motor or car alternator (1KW) is pretty much the same thing isn't it?
Not necessarily. If its a PM BLDC motor, you've got a more or less fixed relationship between volts and RPM. The alternator lets you set that relationship by the field current, fed through the slip rings to the rotor which will give you much better control of loading over a wide speed range.
Coppercone's heat exchanger ideas sound like a *LOT* of work. If you've got access to a milling machine, it would be a lot simpler to just mill two mating serpentine half-channels in two slabs of aluminum, then bolt them together all round the edges with a gasket, drill and tap the edge faces where the two channel ends emerge to bolt on flanged pipe couplings again with gaskets, drill and tap blind holes in the faces for the metal cased resistors and run ordinary automotive coolant through it and the radiator to control corrosion.
Well if you do it just with a mill you wont have good thermal transfer because of surface area. For flats you want broached or cut grooves, you can double/triple surface area this way, which is why I said go with star
you also need coating for aluminum as mold preventers and stuff will destroy it and corrode, or impurities, especia;lly if you use an evaporator
closed loop distilled water or coolant will be alot more mild, but you won't get the concentrated cooling power of an evaporator, you need giant radiators and cooling fans to blow on them, which means more moving parts, or really really giant radiators that don't have moving parts, and you need to worry about sunlight control, etc.. hard to do outdoor radiators I think without moving parts.
A cooling tower is nice because the pump does all the work and its fairly low surface area so you don't have the sun turning it into a water heater so easily.
I mean a regular wet cooling tower that uses its own water to cool, not something more advanced, I think they are the cheapest and intermittent operation means you can get away with the downsides. I would recommend a closed loop one that uses air exchange only if its constant operation to keep down humidity, I think that at that point its worth investing in your facility to have more advanced infrastructure.
Some of the smaller ones you could also probably fit on a cart of some sort so you can keep it in a storage room when not in use to keep it clean. Bigger ones might require a fork lift or some shit.
Otherwise, you can use it, splash it down with soap afterwords using a garden hose, then clean it out ,maybe give it a gentle pressure wash if it gets filthy