Performance analysis of a hydrogen-fueled PAFC triple system for high efficiency

초록

In this study, a new type of triple system combining a phosphoric acid fuel cell (PAFC), a gas turbine (GT) and a steam turbine (ST) is proposed to achieve high power and efficiency. Water is used as the cooling medium of the waste heat recovery system and is directly utilized as the working fluid of the ST. The PAFC is used not only as a power source, but also as an evaporator to convert water into steam for driving the ST. The impact of the synergistic integration of the triple system was investigated for different fuels: natural gas and hydrogen. Also, a parametric analysis and optimization were performed using the operating pressure of the PAFC as the primary design variable. In the natural gas-fueled triple system, as the pressure ratio increased, performance of the system decreased due to the existence of the fuel-reforming process. Unlike the system using natural gas, since the hydrogen-fueled triple system did not require fuel reforming and had high turbine inlet temperature, the optimum pressure ratio was much higher (6.1). At the optimum of the triple system, the system using natural gas showed a 55% increase in power, and the efficiency increased by 5%p compared to the stand-alone PAFC system. The triple system using hydrogen increased the power by 104% and the efficiency by 5%p compared to the stand-alone PAFC system. At each optimum, the triple system using hydrogen as fuel had 31% higher power and 4%p higher efficiency than the triple system using natural gas. In conclusion, a novel efficient PAFC-GT-ST triple system was proposed, and a higher synergistic effect was observed when using hydrogen as fuel. © Proceedings of ECOS 2022 - 35th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems.

키워드