An online sensor-less methanol concentration monitoring method for direct methanol fuel cell based on the voltage decay rate during the rest cycle

Monitoring the methanol concentration is critical for direct methanol fuel cell (DMFC) reliability. However, monitoring the concentration is expensive due to the high cost of concentration sensors. This paper describes an advanced sensor-less method for monitoring methanol concentration during the rest cycle of a DMFC using the voltage decay rate (kvt). Based on the dynamic behavior of methanol mass transfer and reaction in DMFC during the rest cycle, a feedback equation for methanol concentration is constructed in this method. The rationality of the feedback equation is then confirmed through a series of sensitivity analysis experiments at various methanol concentrations, cell temperatures, and load currents. In addition, 1,900 experiments under random conditions simulating practical applications are used to assess the accuracy of the feedback equation. According to the results, 89.6% of the 1,900 experiments have concentration prediction errors of less than 0.05 mol L−1. The mean error and standard deviation of error are found to be 0.005 mol L−1 and 0.031 mol L−1, respectively. These findings point to the desired accuracy and stability of the sensor-less method, as well as promising applications in a variety of scenarios. •A precise 2D DMFC model was built with only 4.5% error for IV polarization curves.•A concise quadratic concentration feedback equation was derived based on the model.•The concentration feedback equation was validated by 1900 random experiments.•The concentration feedback equation achieves prediction errors below 0.05 mol L−1.