Abstract: A fluid-charged heating device comprising a cylindrical housing in fluid communication with a housing extension; a cylindrical rotor disposed centrally and mounted for rotation in said cylindrical housing in spaced relation to provide an annular passage for heat transfer fluid to recirculate between the cylindrical housing and the housing extension. The rotor has a surface with a continuous helical groove along the longitudinal axis of the rotor and rotation of the helically grooved rotor causes fluid shearing, heat-generating cavitation, and recirculation of the heat transfer fluid between the housing and the housing extension.