Modelling of a Hybrid Gas Turbine and Fuel Cell System for Power Generation

Abstract

This paper presents the modelling of a hybrid cycle power generation with gas turbine and fuel cell technologies. The fuel cell used for the model is the Solid Oxide Fuel Cell (SOFC), with helium gas taken as the closed cycle fluid because of its high rate of heat transfer. Due to their ceramic constituent, SOFC can operate at high temperatures in the range of 800oC - 1000oC and requires no precious metal catalysts and is considered the most promising of all high temperature fuel cells.The fuel cell, gas turbine and heat exchanger were modelled and design calculations carried out show that the mass flow rate of hydrogen,the rate of heat exchange from the fuel cell and the gas turbine power output are respectively 0.225kg/s, 5931.46kW and 1087.65kW. A preliminary evaluation of the model was achieved by varying the stoichiometric constant λ and the turbine inlet temperature T3 while the compressor inlet temperature T1 and fuel cell voltage were kept constant at 375K and 0.65volts respectively. The hybrid efficiency increases with increase in turbine inlet temperature and attained 52% at 980K. The increase in stoichiometric constant from 1.25 to 2.0 led to a corresponding increase in the ac power output of the gas turbine from 1.65 to 2.0MW. The hybrid power output is 14MW.