Phase change material composition

A transportable PCM (phase change material) module comprises anumber of PCM packs; a housing for thermally insulting said number of PCM packs from a module's surrounding medium; spaces separating said packs and forming one or more channels for the flow of a fluid; said housing incorporating a fluid inlet and a fluidoutlet; whereby, in use, fluid flows through said channels from said inlet to said outlet.A PCM (phase change material) pack comprises a laminate of a first conducting panel and a second conducting panel enclosing a portion formed primarily of PCM; wherein said portion of PCM incorporates thermal conductors. A PCM (phase change material pack) comprises an envelope of relatively highly thermally conductive material enclosing a portion formed primarily of PCM; wherein said PCM portion incorporates a conductive compound mixed into said PCM which comprises carbon black particles.