Steady-state multiplicity and transient behaviour of a lumped-parameter solid oxide fuel cell

Rai, Harvind Arjun (2017). Steady-state multiplicity and transient behaviour of a lumped-parameter solid oxide fuel cell. University of Birmingham. Ph.D.

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Abstract

The existence of multiple steady-state solutions within a planar, zero-dimensional Solid Oxide Fuel Cell (SOFC) is investigated. The model presented here is a development of the SOFC model by Bavarian and Soroush (2012), where the heat-transfer coefficients are no longer assumed to be constant, and momentum conservation is considered within the gas channels. The steady-state behaviour of the SOFC is investigated for three modes of operation: (i) constant external load; (ii) constant voltage; (iii) constant current. For (i) and (ii), up to three steady-state solutions exists: two stable and one unstable. The main focus is on the first mode of operation, where the effect of the different inlet parameters on SOFC performance is also considered.
The dynamic model is also considered for a Solid Oxide Fuel Cell operating under a constant external load. The different time-scales relevant to this model is investigated to highlight the multi-time-scale nature of the SOFC system. The transient behaviour of the SOFC is investigated for changes in value of the external load resistance R\(_{load}\). R\(_{load}\) is expressed as a smooth function of time such that it changes smoothly from one value to another around 100 seconds. The evolution of different SOFC parameters with time is investigated, as well as the transient behaviour of the SOFC during ignition and extinction. The results show that at least two different operating regimes exist within a Solid Oxide Fuel Cell. The transient behaviour of the SOFC operating along the unstable steady-state branch is also covered.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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