Search Results

This work presents a method to maximize the net power output of an indirect methanol PEM fuel cell system. This method establishes an operating strategy for the air supply based on the stack, air supply and water and thermal management (WTM) sub-system characteristics - holding anode conditions constant. It is shown that operating strategies based on individual components result in the inefficient operation of the overall system. Inclusion of the WTM modifies the optimal operating conditions for both low and high pressure systems. However the results for high pressure show an efficiency gain through reducing air pressure and increasing airflow, the opposite of what is expected. This work also outlines the components and issues not included and their importance in system operation.

A detailed simulation of a load-following indirect methanol fuel cell (IMFC) system was performed by the University of California - Davis fuel cell vehicle modeling program (FCVMP) in order to determine the realistic steady-state and dynamic performance of such a system. The first part of the paper includes a basic description of the model and the control of the system. The interaction between the fuel processor and the anode side of the stack is shown to have dynamic load following limitations and a subsequent control strategy is described to solve this problem. The interaction between the air supply, the cathode side of the stack and the water recovery is shown to have several optimization opportunities. In the second part of the paper, we find that the steady state efficiency of the system peaks at approximately 52% at around 5% of full power. The 25% of full power steady-state system efficiency is approximately 45% and the full power efficiency is approximately 27%.