Combined solid oxide fuel cell, micro-gas turbine and organic Rankine cycle for power generation (SOFC–MGT–ORC)

• A micro-scale power generation system is designed.
• The cycle consists of a SOFC, MGT and ORC.
• The cycle electrical efficiency can reach 61%.
• The cycle saves up to 45% fuel with respect to conventional systems.

In the present paper, a novel cycle combining three technologies of solid oxide fuel cell, micro gas turbine, and organic Rankine cycle is proposed to produce power in micro scale. The high quality exhaust of fuel cell is used in a micro gas turbine. The micro gas turbine exhaust is then used in a heat recovery steam generator for steam generation in a Rankine cycle. The cycle is simulated thermodynamically and the fuel cell model is validated with experimental data available in the literature, and good agreement is reached. Parametric study is carried out to evaluate the cycle behavior. In addition a sensitivity analyses is done to investigate the sensitivity of the cycle electrical efficiency by changing 10 design parameters such as current density, fuel flow rate, steam to carbon ratio, fuel cell heat loss, fuel utilization factor, reformer temperature, fuel cell working pressure, and the Rankine cycle minimum and maximum pressure. In addition a pinch analysis is done for the steam generator to evaluate the pinch point temperature difference. The pinch point temperature difference in the steam generator is 10.24 °C for a practical case. The results show that in micro-scale power generation, fuel saving of about 45% is achievable and the overall efficiency can reach more than 65%.