Design and Optimization of an Innovative Solid Oxide Fuel Cell-Gas Turbine Hybrid Cycle for Small Scale Distributed Generation

Distributed power generation and cogeneration is an attractive way toward a more rational conversion of fuel and biofuel. The fuel cell-gas turbine hybrid cycles are emerging as the most promising candidates to achieve distributed generation with comparable or higher efficiency than large-scale power plants. The present contribution is devoted to the design and optimization of an innovative solid oxide fuel cell-gas turbine hybrid cycle for distributed generation at small power scale, typical of residential building applications. A 5kW planar SOFC module, operating at atmospheric pressure, is integrated with a micro gas turbine unit, including two radial turbines and one radial compressor, based on an inverted Brayton cycle. A thermodynamic optimization approach, coupled with system energy integration, is applied to evaluate several design options. The optimization results indicate the existence of optimal designs achieving exergy efficiency higher than 65%. Sensitivity analyses on the more influential parameters are carried out. The heat exchanger network design is performed for an optimal configuration and a complete system layout is proposed. An example of hybrid system integration in a common residential building is discussed. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.