Energy-exergy analysis of an integrated small-scale LT-PEMFC based on steam methane reforming process

This study reports a novel integrated system for power generation with on-site produced hydrogen and heat recovery. The main equipment of the integrated system includes a steam methane reforming (SMR) reactor for hydrogen production, a palladium membrane (Pd-M) unit for hydrogen purification, a waste heat collector (HC) unit for heat recovery, and a low-temperature proton exchange membrane fuel cell (LT-PEMFC) for power generation. ASPEN Plus and MATLAB/Simulink jointed simulation model is used to establish an accurate model for the whole integrated system. Moreover, for the SMR reactor, it is found that the RPlug reactor simulation module is more appropriate compared with the RGibb module. Then a detailed parametric analysis is carried out to estimate the effects of hydrogen utilization, the SMR reactor operating temperature, and the current density of the PEMFC stack on the overall energy and exergy efficiency of the integrated system. Finally, thermodynamic analysis is performed on the integrated system with S/C of 3.0, SMR reaction temperature of 700 degrees C, PEMFC hydrogen utilization rate of 0.8, and power generation of 520 W, delivering energy and exergy efficiencies as high as 47.4% and 45.7% under these operating parameters. The thermodynamic analysis shows that the PEMFC stack is the primary source of the system exergy destruction (326.27 W) with 34.33% of the relative exergy destruction ratio.

Automated summary

This study introduces a novel integrated system for power generation utilizing on-site produced hydrogen and heat recovery. Through detailed parametric analysis and thermodynamic evaluation, the system achieved high energy and exergy efficiencies under specific operating parameters. The primary source of exergy destruction within the system was identified as the PEMFC stack.