摘要 |
An electrical heating element 35, 35' is located in a thin walled, closed metal tube or sleeve 37, 37' which is packed with a packing material 38, 38' of good heat conductive, insulating properties; the electrical heating element is a spirally wound resistance heater embedded in the insulating packing. A solid electrolyte body 11, 68 surrounds at least a portion of the thin walled metal sleeve and is positioned in heat exchange relation therewith. The solid electrolyte body may be a closed tube 11 or may be applied as a ring element 68 over the thin walled metal tube with an insulating material layer 66 interposed. |