Heat-exchanger

摘要

A body comprising a ceramic electrical resistance material of positive temperature coefficient of resistivity adapted to display a sharp increase in resistivity when heated to a selected temperature has passages extending through the body between opposite ends of the body for passing fluid through the passages in heat-exchange relationship to the body and has means electrically contacting spaced-apart portions of the body for directing electrical current through the body to self-heat the body. The body is made with an improved structure in an improved manner and is particularly adapted for use as a self-regulated fluid heater within a small or irregularly-shaped conduit or the like.