Patent ID: 6080973
Filing Date: 2000-06-27
Classification: F24H,G05D

Abstract:
A heater comprising:a polymeric body having an elongated hollow, and an inlet opening and an outlet opening in communication with said hollow for flowing fluid therethrough;an electrical resistance heater having a heating element of a material exhibiting a positive temperature coefficient of resistance, said heating element disposed in said hollow of said polymeric body and in heat transfer communication with fluid flowing through said hollow;an input terminal for receiving electrical power and supplying said electrical power to said heating element to produce a current in said heating element to generate heat; anda controller for sensing current flow through said heating element and determining a resistance related value of said heating element, said controller further determining a first derivative of said resistance related value as a function of time and controlling the electrical power supplied to said heating element as a function of said first derivative so that the controller prevents overheating of the polymeric body.