Waste heat recovery from a flame-assisted fuel cell utilizing recompression supercritical CO2 Brayton and dual-pressure organic Rankine cycles

Abstract

A Flame-assisted Fuel Cell is the combination of the Solid Oxide Fuel Cell with fuel-rich combustion. In this work, two different bottoming power cycles i.e., the RSCBC and the DORC are employed to the waste heat recovery of a methane-fueled Flame-assisted Fuel Cell (FFC). Energy and exergy analyses of the FFC-RSCBC combined cycle show that this combination improves the energy and exergy efficiencies from 18.62% to 22.91% and 18.05%–22.21%, respectively. The cathode inlet air is preheated by the exhaust gases from fuel-lean combustion in the FFC-DORC combined cycle, which increases the efficiency. The improvements in energy and exergy efficiencies are 20.54–20.94% and 19.91–20.3% respectively. Comparison of the performance of the proposed cycles show that the FFC-RSCBC generates more power compared to the FFC-DORC (W˙FFC−RSCBC=184.4kW,W˙FFC−DORC=168.6kW) and the exergy loss of FFC-RSCBC and FFC-DORC is 22.02 kW and 3.46 kW, respectively.