Heat of liquefaction and solidification is transmitted between a heat storing material undergoing the phase transition and a heating medium in a heat exchanger by means of a partly gaseous, partly liquid fluid sealed in a heat pipe a portion of which is received in the container for the aforementioned...http://www.google.es/patents/US4131158?utm_source=gb-gplus-sharePatente US4131158 - Storage arrangement for thermal energy
