Composite covers for isothermal packs - with one reflective film cover and one conductive film cover to orient heat transfer

摘要

Covers for an isothermal pack, (i.e. a pack which may be used as a heat source at a specific temp. for a sustained period while preheated contents pass through a phase change while cooling) are made of flexible materials which, on >=1 face exhibit, a high coefft. of thermal conductivity and on at least the opposite face have a surface which will reflect infra red radiation internally. Pref. the conductive cover is of a tough aluminium based foil (10 mu m) or a plastic film containing metallic or other thermally conductive filler particles, and the reflective cover is of metallised polyolefin (20 mu m) or polyester (15 mu m) film. Pref. the pack incorporates one or more small integral subsidiary pockets incorporating liquid crystal displays to indicate when the pack temp, reaches or deviates from the phase transition temp. range, e.g. 45-55 degrees C for solidification of a conventional complex paraffinic mixture. The covers enhance by >=20% the thermal efficiency of heat transfer to a body adjacent to the conductive cover.