Abstract: An electrically heated dryer for articles comprises a drying container and an air duct leading thereto for directing air in a stream through the duct and into the container. An electric resistance heating element is provided in the duct and comprises an expanded resistance metal sheet of separated strands and connecting bridges with the strands at an angle to the sheet and generally parallel to each other. The element is serpentively arranged in the duct in successive substantially planar reaches spanning the duct with the strand surfaces of the upstream reaches arranged substantially parallel to the direction of air flow for streamline wiping action thereof by the air stream. A planar reach downstream of said upstream reaches is arranged with its strand surfaces substantially non-parallel to the direction of air stream flow to aid in mixing the heated air prior to delivery into the container.

Abstract: A generally rectangular, self-supporting, unitary high temperature electrical resistance heater adapted for generally horizontal suspension within a high temperature furnace in which the heating element is composed of a flat resistor ribbon folded to form a series of continuous and substantially parallel beam-like heater segments disposed in grate-like fashion. The ribbon heater segments are retained in their parallel configuration by a plurality of refractory insulators disposed between and supported solely by the beam-like segments. The resulting furnace heater offers advantages of light weight, high radiation efficiency and minimum thermal inertia.

Abstract: A high temperature unitary electrical resistance heater which is mechanically supported throughout its active length but spaced from a refractory base with the heating element being substantially free of the supporting structure to provide an efficient heater having relatively low thermal inertia while being rigidly supported for high temperature operation. A flat continuous electrical resistor ribbon is folded in a multiple loop helix-like configuration formed of a plurality of straight segments and a repetitive array of folded, overlapped corner portions. A strut is interposed within each folded corner and welded therein, outwardly extending end portions of each strut being rigidly secured in a refractory base structure with the resistor ribbon being spaced along its active length from the base structure.

Abstract: A high temperature unitary electrical resistance heater which is mechanically supported throughout its active length but spaced from a refractory base with the heating element being substantially free of the supporting structure to provide an efficient heater having relatively low thermal inertia while being rigidly supported for high temperature operation. A flat continuous electrical resistor ribbon is disposed in a multiple loop configuration having a plurality of spaced heater segments with flat confronting surfaces and a plurality of legs outwardly extending from an edge of the ribbon and secured within a refractory base to support the ribbon in spaced relation to the refractory base.

Abstract: A monolithic electrical resistance heater element is produced from mixing particles of a conductive carbonaceous pyropolymer that have been deposited on a refractory metal oxide with a heat unifiable ceramic, such as alumina, cordierite, spodumene, etc., and then forming a resulting rigid "honeycomb type" of semiconductive ceramic substrate. The carbonaceous pyropolymer particles are preferably formed from heating an organic pyrolyzable substance in contact with alumina particles, or other metal oxide particulates, at a temperature above about 400.degree. C.