Solid Oxide Fuel Cell Gas Turbine System Research Articles

Parametric Thermodynamic Analysis of a Solid Oxide Fuel Cell Gas Turbine System Design Space

A parametric study of a solid oxide fuel cell-gas turbine (SOFC-GT) hybrid system design is conducted with the intention of determining the thermodynamically based design space constrained by modern material and operating limits. The analysis is performed using a thermodynamic model of a generalized SOFC-GT system where the sizing of all components, except the fuel cell, is allowed to vary. Effects of parameters such as pressure ratio, fuel utilization, oxygen utilization, and current density are examined. Operational limits are discussed in terms of maximum combustor exit temperature, maximum heat exchanger effectiveness, limiting current density, maximum hydrogen utilization, and fuel cell temperature rise. It was found that the maximum hydrogen utilization and combustor exit temperature were the most significant constraints on the system design space. The design space includes the use of cathode flow recycling and air preheating via a recuperator (heat exchanger). The effect on system efficiency of exhaust gas recirculation using an ejector versus using a blower is discussed, while both are compared with the base case of using a heat exchanger only. It was found that use of an ejector for exhaust gas recirculation caused the highest efficiency loss, and the base case was found to exhibit the highest overall system efficiency. The use of a cathode recycle blower allowed the largest downsizing of the heat exchanger, although avoiding cathode recycling altogether achieved the highest efficiency. Efficiencies in the range of 50–75% were found for variations in pressure ratio, fuel utilization, oxygen utilization, and current density. The best performing systems that fell within all design constraints were those that used a heat exchanger only to preheat air, moderate pressure ratios, low oxygen utilizations, and high fuel utilizations.

Research status and advances in modeling and control of solid oxide fuel cell gas turbine hybrid generation system

Solid oxide fuel cell gas turbine (SOFC-GT) hybrid generation system is one of highly-efficient clean generation technologies in the future. Research of modeling, optimization and control of the hybrid system is very meaningful to the system integration and commercialization. By introducing the state-of-the-art achievements including mechanistic and semi-empirical model of single cell, stack model, hybrid system model, system integration and optimization, control-oriental dynamic model and control of distributed generation system, the multi-scale independent research and development strategy are presented. Based on the general mechanistic cell model which is suitable for high fuel utilization and multi-component fuel, more accurate semi-empirical or approximate analytical model can be developed for system-level analysis. Based on building the multi-scale model library with independent intellectual property rights, the platform of design and optimization for steady-state system analysis is provided. In the V-type mode, the advanced control algorithms are developed to form the rapid control prototype based on the analysis of system dynamic characteristics. Meanwhile, the hardware-in-the-loop simulation technology with real-time controller can be used for the pre-integration of SOFC-GT system.