Is there a Portable air conditioner without exhaust?

I'd like to invite you to consider for a moment what the "window exhaust" is for.

Air conditioners work by making the second law of thermodynamics run, locally, in reverse: moving heat from a cool place to a hot place. In order to put cool air out the front, they've got to put hot air out the back. Or at least put it somewhere.

Hopefully it's fairly obvious that if you've got an air conditioner sealed in a windowless room, there's no place for the hot air to go, so the room is not going to get any cooler. In fact, it's going to be slightly warmer than it would if the air conditioner wasn't there at all, because running the air conditioner produces some amount of heat.