PNNL

Abstract

In this research, a Simulink model of a standalone vehicular solid-oxide fuel cell (SOFC) auxiliary power unit (APU) is developed. The SOFC APU model consists of three major components: a controller model; a power electronics system model; and an SOFC plant model, including an SOFC stack module; two heat exchanger modules; and a combustor module. This paper discusses the development of the nonlinear dynamic models for the SOFC stacks, the heat exchangers and the combustors. When coupling with a controller model and a power electronic circuit model, the developed SOFC plant model is able to model the thermal dynamics and the electrochemical dynamics inside the SOFC APU components as well as the transient responses to the electric loading changes. It has been shown that having such a model for the SOFC APU will benefit design engineers to adjust design parameters to optimize the performance. The modeling results of the heat-up stage of an SOFC APU and the output voltage response to a sudden load change are presented in the paper. The fuel flow regulation based on fuel utilization is also briefly discussed.