Abstract: Fuel reformers and methods for using fuel reformers are disclosed herein. In one embodiment, the fuel reformer can comprise: an oxidant inlet, a mixing zone capable of receiving the oxidant and vaporized fuel to form a fuel mixture, a reforming zone disposed downstream of and in fluid communication with the mixing zone, wherein the reforming zone is capable of converting the fuel mixture into a gas stream, and a passive heat exchanger disposed in thermal communication with the gas stream and capable of heating the fuel prior to introduction to the mixing zone.