Patent ID: 8568495

Claim:
An evaporator of a fuel reformer comprising: a first stage having a first chamber, a first first opening and a first second opening, the first first opening and the first second opening for allowing a first fluid to enter into and exit from the first chamber; a second stage stacked together with the first stage as a stack of the stages, the second stage having a second chamber, a second first opening and a second second opening, the second first opening and the second second opening for allowing a second fluid to enter into and exit from the second chamber; a first fin structure in the first chamber and for increasing a heat-exchange surface area with a flow of the first fluid within the first chamber; and a second fin structure in the second chamber and for increasing a heat-exchange surface area with a flow of the second fluid within the second chamber, wherein each of the first and the second fin structures comprises: a plurality of first fins each extending along a first direction in a first wave pattern having a first period; and a plurality of corresponding second fins each extending along the first direction in a second wave pattern having the first period and being offset from the first wave pattern by one half of the first period, the second fins being arranged alternately with the corresponding first fins, wherein the first fin structure substantially contacts inner surfaces of the first chamber, wherein the second fin structure substantially contacts inner surfaces of the second chamber.