The performance of thermal based modified solid oxide fuel cell (SOFC) model under different DC load conditions

In this paper, a thermal-based dynamic model of a Solid Oxide Fuel Cell under different direct current load conditions is improved by using our previously developed fuel cell model, which includes ohmic, activation and concentration voltage losses, thermal dynamics and methanol reformer. The modified Solid Oxide Fuel Cell model covers restriction of fuel utilization factor. Hence, the voltage and power of the Solid Oxide Fuel Cell stack are limited to avoid excessive fuel flow and temperature. The Solid Oxide Fuel Cell model is developed in a Matlab/Simulink environment and tested for different direct current load conditions, which are step, ramp, random and stair-case loads. The simulation results show that the modified Solid Oxide Fuel Cell model can be used to precisely follow the direct current load variations. This is true, because reaching the steady state of the system takes a shorter time for the ramp load, and takes a longer time for the step load. Besides, the limitation of the fuel utilization factor can be seen more clearly from the system with the stair-case load.