4E analysis and multi-objective optimization of a novel multi-generating cycle based on waste heat recovery from solid oxide fuel cell fed by biomass

Abstract

The present study optimizes a novel developed cycle including solid oxide fuel cell (SOFC) fed by synthesis gas produced from biomass as well as gas turbine (GT), supercritical carbon dioxide cycle (SCO₂), transcritical carbon dioxide cycle (TCO₂), Organic Rankine Cycle (ORC), thermoelectric generator (TEG), and reverse osmosis (RO)- based desalination. Energy, exergy, exergoeconomic and exergoenvironmental analyses on the developed cycle were investigated. Multi-objective optimization was carried out using of Genetic algorithm using generated power and exergy destruction as objective functions. Sankey diagram data indicate that afterburner holds the highest portion of the total exergy destruction 46.5% (692.24 kW), followed by SOFC which is 20.48% (304.51 kW). Moreover, optimization results showed that the total net power, first and second laws of thermodynamic efficiencies increased by 2.6%, 0.96% and 0.83%, respectively, while exergy destruction decreased by 1%. Furthermore, such a power increase (18.53 kW) using the freshwater produced by RO leads to daily production of 17040 liters of drinking water. According to the exergoeconomic analysis, the minimum flow value pertains to GT at a value of 0.0119 $/GJ, while the TCO₂ turbine has the highest value which is 0.2867 $/GJ. The system product cost rate and exergy destruction cost rate reached 27.0353 $/h, and 10.7012 $/h, respectively. In the case of the exergoenvironmental one, the maximum environmental impact is related to the SCO₂ turbine 0.0212 Pts/GJ, while SOFC has the lowest (0.0002 Pts/GJ). The system product environmental impact and exergy destruction were achieved at optimum values of 2.7503 $/h, and 4.1576 $\times {10}^{-7}$ $/h, respectively.