Patent ID: 7484590

Claim:
A fuel cell system comprising: an electric generator configured to generate electricity through an electrochemical reaction between air and fuel; an air feeder configured to supply air to the electric generator, the air feeder comprising an inlet and an outlet; and a muffler in fluid communication with one of the inlet and outlet of the air feeder, the muffler comprising: a first air passageway having a first end and a second end, the first air passageway having a first length extending along the first air passageway between the first and second ends of the first air passageway; and a second air passageway having a first end and a second end, the second air passageway having a second length extending along the second air passageway between the first and second ends of the second air passageway, the first end of the second air passageway being connected to the first end of the first air passageway, the second end of the second air passageway being connected to the second end of the first air passageway, the second length being different from the first length, wherein the second air passageway is spaced apart from the first air passageway between the first and second ends of the first air passageway, and wherein the first length of the first air passageway and second length of the second air passageway are configured such that the muffler resonates at a frequency of noise generated by the air feeder.