Abstract: An electrical resistance heater includes interior surface bounding a fluid passage therein configured so as to disrupt lamellar flow of fluid and impart cross-mixing to the fluid. In specific construction, heaters herein include a housing, or heating cartridge insert to the housing, having a fluid inlet port and a fluid outlet port, a fluid passage extending longitudinally with the housing between the fluid inlet port and the fluid outlet port and bounded in part by surface which is configured to impart lateral displacement to fluid traversing the passage, and an electrical resistance heater disposed in such passage.

Abstract: Apparatus for electrically heating a fluid medium includes a housing (18) having an inlet channel (54) and an outlet channel (60) communicating with a central passage (62). A heating cartridge (38) is resident in the central passage (62) and has a web (90) defining first and second series connected interior channels in communication respectively with the inlet and outlet channels (54, 60). A continuous electric resistance heating coil (94) extends successively through the interior channels and includes a mechanically stressed portion (94a) bridging the first and second interior channels. The bridging portion (94a) is electrically shunted by an electrically conductive member (96) to eliminate current flow therethrough to lessen the likelihood of burnout or failure of the stressed portion (94a).