An algorithm for sensor-less fuel control of direct methanol fuel cells

We report an algorithm for real-time control of the fuel of a DMFC. The MEA voltage decay coefficients [e1, e2], and I-V-T, M′-I-T, and W′-I-T curves (where I is the current, V the voltage, T the temperature, and M′ and W′ the methanol and water consumption rates, respectively) of n fuels with specified methanol concentrations CM,k (k = 1, 2,…, n) are pre-established and form (I,V,T), (M′,I,T), and (W′,I,T) surfaces for each CM,k. The in situ measured (I,V,T)u after voltage decay correction is applied to the n preset (I,V,T) surfaces to estimate CM,u (the CM corresponding to (I,V,T)u) using an interpolation procedure. The CM,u is then applied to the n preset (M′,I,T) and (W′,I,T) surfaces to estimate cumulated “methanol” and “water” consumed quantities . Thus in a real-time system, the CM and total quantity of fuel can be controlled using the estimated CM,u and cumulated “methanol” and “water” consumed quantities.