Abstract: A heat transfer system comprising a pair of zones positioned at respective locations of differing temperatures between which heat is transferred; a first element, one surface of which conducts heat; a second element, one end of which communicates with one of the pair of zones and the other end of which communicates with the other of the pair of zones and one surface of which conducts heat and is slidably engaged with the heat-conducting surface of the first element and means for establishing oscillatory movement of the second element between the pair of zones such that the heat-conducting surface thereof slidably engages the heat-conducting surface of the first element and such that the ends thereof do not communicate with the other of the pair of zones.