Part load operation of a SOFC/GT hybrid system: Dynamic analysis

Abstract

The hybrid solid oxide fuel cell and gas turbine system is a promising solution in the future small scale power plants, thanks to its high energy/power efficiency with low environmental impact. In fact, due to the synergistic effect of using a high temperature fuel cell such as Solid Oxide Fuel Cell (SOFC) and a recuperative gas turbine (GT), the integrated system efficiency can be significantly improved. The goal of this paper is to develop a complete dynamic model of a hybrid system (HS) for the optimization of the plant components, with particular attention to the heat exchangers, also in consideration to the transient response (in terms of the electricity and the interaction between SOFC and GT) of the whole system. This research activity represents the following part of [1], in which the authors analyzed the steady state behavior of the hybrid system through a zero dimensional model developed in Aspen Plus environment. Specifically, in this paper all the model components presented in [1] were implemented in Matlab®Simulink environment. With the aim to achieve a right dimensioning of the main plant components to guarantee a certain inertia of the system and evaluate the system global performance (efficiency, time response), suitable simulations were carried out. Moreover, the interaction between the system components was investigated during transients, with particular attention to the inertial effect of gas turbine and heat exchangers also on the fuel cell, even if maintained at constant load. The developed dynamic allowed the analysis of the fully functioning of the hybrid system, together with the optimization of the plant components and its control logic at gas turbine part load. Then, the final aim of this study is to fill the void present in the technical literature concerning the analysis of dynamic interaction between components of SOFC/GT hybrid system.