Exergy and Energy Evaluation of Bio-ethanol Steam Reforming in a Catalytic Membrane Reactor
Résumé
The exergy efficiency and exergy destruction of a catalytic membrane reactor were evaluated based on inlet and outlet streams using experimental data. To calculate the exergy content of chemical species, three different parts i.e. physical exergy, chemical exergy, and exergy of mixing has been taken into account. For the system under study, ethanol steam reforming (ESR) experiments were performed over PdRh/CeO2 catalyst in a membrane reactor (MR) containing Pd-Ag membranes. Experiments were performed at T=873-923 K, P=4-12 bar, and fuel flow rates of 50 and 100 µl/min. The fuel was a mixture of ethanol and distilled water with steam to carbon ratio=1.6, 2, and 3. The exergy efficiency of the system was evaluated considering both an insulated reactor (without heat loss), and non-insulated reactor (with heat loss). The significant effect of pressure and temperature on the exergy efficiency was observed. Exergy efficiency up to around 50% was reached in the case of insulated reactor at 12 bar and 923 K. It was concluded that the highest amount of exergy was destructed by heat losses. The study showed that the exergy content of the retentate gas especially at lower pressures can provide the reactor with a fraction of its required heat at steady state conditions. This notably increased the exergy efficiency of the system. Thermal efficiency of the system was between 70-90% for insulated reactor system and decreased to between around 40-60% when the heat loss was considered.