A fuel delivery system for an energy conversion device includes a fuel deoxygenator and an oxygen scavenger module for removing dissolved oxygen and increasing the usable cooling capability of a fuel. Fuel emerging from the fuel-deoxygenating device flows into the oxygen-scavenging module where a second portion, smaller than the first portion of oxygen is removed from the fuel. The combination of the oxygen scavenger and the fuel deoxygenator provides an increase in removal of dissolved oxygen relative to the use of either device alone. The combination provides the desired increase in deoxygenation of fuel without the corresponding increase in device size.