Air Conditioning - how well do the self contained units work?

Looking for reports of suitability from people who've used one of the common (Home Depot / Lowes ) portable air conditioner units. Need to know how good a job they'll do cooling a room.

Judging by what I know of thermal principles, the can't work. Where does the heat go? We know that to cool/chill air, you remove heat from it. In other systems, the heat is "pumped" outside. With the self contained unit in the room, seems like it could never get ahead because it's not isolating the heat anywhere.

Additionally, most of your air chillers have dehumidifcation as a by-product. So where's the water going in these units? Maybe they've got a concealed bucket you have to go dump periodically.

Anyway, I'd like to get a couple for use during power outages when we're running on our gensets, but need to know first that they really work. Otherwise, I'll use window units.

For the condenser discharge the hot air is piped via a hose kind of like a drier vent line and piped outside. The condensate is usually caught in a bucket and emptied occsionally as needed or pumped out.

They work ok.