I recently acquired a plate chiller for my home brewery. Here it is in action.
Edit: For those not sure what is going on here (Bob), beer production involves boiling up malt and hops. At the end of the boil, you want to chill the wort (what it's called before it's fermented) to a suitable temperature for pitching yeast. That's what this device is for. It could also be called a heat exchanger. Hot wort and cold water go in through separate flow paths, make contact along the surfaces of 30 brazed plates, and cold wort and hot water come out. Now I can pitch the yeast and get fermentation underway. I could just let it cool down naturally, but it will take a day or two to reach pitching temperature and increases the risk of a wild yeast or bacteria infection. Happy?