Abstract: A portable heat exchange unit for cooling a medium including a vessel adapted to contain a discrete quantity of a compressed or liquefied gas wherein the vessel includes a wall arranged to be placed in contact with the medium to be cooled, a valve for operatively controlling the release of the gas from the vessel, a panel positioned adjacent and inside the wall of the vessel for operatively directing the gas into heat exchange contact with the wall of the vessel and arranged to release gas from the top of the panel, and a means for exhausting the gas from the vessel. The panel has ridges thereon and engages the wall so as to form a plurality of channels between the ridges and the wall.