The aim of this work is to develop dynamic models for two types of kW-scale
molten carbonate fuel cell (MCFC) systems on the basis of experimental dat
a. The dynamic models are represented as a 3 x 3 transfer function matrix f
or a multi-input and multi-output (MIMO) system with three inputs and three
outputs. The three controlled variables which severely affect the stack pe
rformance and lifetime are the temperature difference in the stack and the
pressure drop at. the anode and the cathode. Three manipulated variables, n
amely, current load, fuel and oxidant utilization, are selected to keep the
three controlled variables within their safety limits for the reliable ope
ration and protection of the system in case of emergency. Each element in t
he transfer function matrix is in the form of a first-order model using a s
imple, unit step, response test during operation. The non-zero off-diagonal
elements in the transfer function matrix show that some interactions exist
among the operating variables, and two zeros show no interaction between f
uel and oxidant flow without gas cross-over. The stability of both dynamic
models is analyzed using the relative gain array (RGA) method. Large diagon
al elements in the RGA matrix show that the pairing between the manipulated
and controlled variables is appropriate. Proper pairing is also proven by
the singular value analysis (SVA) method with a smaller singular value in e
ach system. (C) 2001 Elsevier Science B.V. All rights reserved.