Design optimization of a SOFC-based CHP system through dynamic analysis

In this paper a complete dynamic model of a solid oxide fuel cell (SOFC)-based residential cogenerative (CHP) energy system has been developed, with particular attention to the heat exchangers, also in consideration to the transient response (in terms of the electricity and heat production) of the whole system. At first, the model has been implemented in Aspen Plus environment to evaluate the thermo-chemical operating conditions of the system and, subsequently, all the system components have been evaluated in Matlab Simulink environment to analyse CHP system behaviour at variable electric loads. With the aim to achieve an optimal dimensioning of the main plant components to guarantee a suitable inertia of the system and evaluate the system global performance (efficiency, time response), suitable simulations were carried out. The global CHP FC dynamic response, in term of the current/voltage delivered by the SOFC and the hot water supplied, under a fixed load step (from 2200 to 3000 W), has been determined resulting in a delay respectively equal to 220 and 100 s. It was also evidenced the relevant inertial effect of the steam generator and the cathodic regenerator of the SOFC operation. (C) Copyright 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.