Working fluid in the wick absorbs heat and and evaporates. The vapourised fluid mixes with the vapour phase which is moving in the center of the pipe. Due to tendency of moving towards lower temperature, vapour reaches the radiating surface to transfer the heat to the heat sink. By low heat energy the vapour condenses. Annular Wick structure helps in movement of condensed vapour to the heat extracting point and again this cycle takes place.

Driving mechanism is the temperature difference between source and the radiator.

=== Louvers ===