DESIGN AND CONTROL OF HIGH TEMPERATURE PEM FUEL CELL SYSTEMS USING METHANOL REFORMERS - AIR OR LIQUID HEAT INTEGRATION - SØREN J. ANDREASEN ASSOCIATE PROFESSOR, FUEL CELL AND BATTERY RESEARCH GROUP

Outline 2 Introduction System control approach Methanol reformers and HTPEM fuel cells Air heat exchange Liquid heat exchange System control challenges Conclusion

System control approach 3 System Design Component Characterization /Modelling Control Strategy Development Controller Evaluation /Implementation

PBI-based MEAs have a high tolerance to CO A liquid fuel, such as methanol is easily accessable and storable Heat can be utililzed in fuel conversion System energy density increase is ”cheap” System size and complexity increases Impurities are introduced Reformed methanol HTPEM fuel cell systems 4

Complicated system dynamics often require hybridization with electrical energy storage for high lifetime and reliability Improvements in load following could be attained using control schemes Applications – Hybridization 5

Cathode air cooled FC stacks have high quality waste heat that can be directly transferred and used for evaporation of reformer fuel. Proper heat integration and design is required to avoid high BoP consumption. Reformer system - air heat exchange 6

Individual system components are characterized ex-situ, such that fuel cell stack and reformer system behaviour can be separated. Fuzzy logic / Neural network models of internal system states, can be developed Model based control approaches are implemented in system software and system improvements are quantified. Reformer system - air heat exchange 7 Serenergy H3-350 off-grid battery charger (HTPEM + SR)

Reformer system - air heat exchange 8 Example: Extensive ex-situ reformer output gas measurements using gas analyzers create the foundation for ”learning” system behaviour by an Adaptive Neuro-Fuzzy Inference System (ANFIS) model. Proper prediction of gas composition, anode stoichiometry, etc. can enable higher efficiency, reliability and lifetime.

Reformer system - liquid heat exchange 9 Liquid heat transfer can minimize system size and BoP power consumption. System logistics are more conventional. Several system topologies are usable depending on application utility heat and demand.

Pump flow determines usable hydrogen flow in the FC anode, but fuel evaporation and conversion need to be considered. A modelbased approach can be used for proper feedforward contol and determination of system setpoints. For example ANFIS modelling can provide high prescision state prediction based on experimental results avoiding undesired system operating conditions. System control challenges 10

Efficient and reliable HTPEM fuel cell systems are at a development stage, where system design and control are increasingly relevant. Fuel cell systems are excellent part load performers, but lag, complex systems dynamics and expensive state monitoring can limit load following capabilities and system performance. Conclusions 11

The authours would like to gratefully acknowledge the financial support from the EUDP program and the Danish Energy Agency for sponsoring the project :COmmercial BReakthrough of Advanced Fuel Cells - (COBRA) Acknowledgements 12 Thank you