A thermally sprayed gas heater comprises a gas flow apparatus that propels a gas through a housing; and a thermally sprayed heater bonded to a surface of the apparatus, the heater positioned to heat the gas flow in the housing. In other aspects, a heater system for a turbulent flow gas duct comprises...http://www.google.fr/patents/US20080217324?utm_source=gb-gplus-shareBrevet US20080217324 - Gas heating apparatus and methods