To study the cold start of muti-stack fuel cell system (MFCS), a novel thermal
management subsystem structure and corresponding cold start strategies are
proposed. Firstly, leveraging the distinctive configuration of the MFCS that can
be sequentially initiated, we augmented the existing thermal management
subsystem with the incorporation of two additional collection valves and two
bypass diverter valves, which affords an increased degree of flexibility in the
formulation of cold-start strategies. Secondly, we innovatively propose a
hierarchical auxiliary heating cold start strategy and an average auxiliary
heating cold start tailored for MFCS consisting of power levels of 20 kW, 70 kW,
and 120 kW. Furthermore, we have developed a controller to address temperature
control challenges during the start-up process. The results demonstrate that the
multi-stack hierarchical auxiliary heating cold start strategy yields a
significant reduction in energy consumption and startup time during the
cold-start process, in comparison to the average preheating strategy. Moreover,
when prioritizing the preheating of the 20 kW stack, its energy consumption
metric and start-up time are further improved by preemptively preheating other
stacks, resulting in a 20% reduction in startup time and a concurrent 20.39%
decrease in energy consumption.