If we apply heat to flame to a fork we can feel the heat move along it's length. Put an ice cube on it and the heat is spent moving into the ice melting some of it, therefore the cool feeling that we might mistaken for cold moving, instead it is heat moving into cold. All examples of cooling and warming are one direction. Heat moves, cold does not.
This is the action in the fridge or airconditioner, heat is being moved out and replaced by less heat through gasses that in vacuum vessels boil at lower temperatures than surrounding temperatures. This boiling off of the heat is expended through fins or fans or baths.
The Alaska pipeline sets on permafrost that is kept frozen by pipes into the ground under each foundation. The pipe is a sealed vacuum tube with a little water in it. The degree of vacuum (negative atmosphere) determines when the water boils. Water boils in a vacuum at temps other than 212°f. These are set to boil at temps of the typical permafrost, when winter cold falls below these values the heat syphon moves heat in the permafrost to the cooler air thus freezing the permafrost to a far lower temperature enabling it to get through the summer without thawing and sinking the pipeline.
|check out cooling fins on top|