A self-supported 40W Direct Methanol Fuel Cell (DMFC) system has been developed and benchmarked for its performance. The system consists of a DMFC stack comprising 15-cells with an electrode area of 45cm2, and auxiliaries comprising a methanol sensor, a liquid-level indicator, fuel and air pumps that consume a total power of about 5W. The self-supported system addresses issues (a) related to water recovery from the cathode exhaust, (b) maintaining a constant methanol-feed-concentration, and (c) the thermal management in the system. Methanol and water are pumped to the methanol-mixing tank where the liquid level is monitored and controlled with the help of a liquid-level indicator. During the operation, concentration of methanol in the solution at the outlet of the stack is monitored, and required amount of methanol is added in the feed tank to restore the initial concentration employing a methanol-loop system connected to a methanol sensor that helps monitoring and controlling the system output at a steady value; product water from cathode is recovered and re-circulated for diluting the methanol feed as desired. The feed-rate requirements of methanol fuel and oxidant air are optimized for the stack capacity of 40W. The salient features of the system are: (i) flexible and modular construction, (ii) controlled-output power and (ii) easy start-up and stop. The self-supported DMFC system is ideally suited for military and aerospace applications.

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