Multi‐objective performance optimization of irreversible molten carbonate fuel cell–Stirling heat engine–reverse osmosis and thermodynamic assessment with ecological objective approach

Abstract

This paper aims to investigate a hybrid cycle consisting of a molten carbonate fuel cell (FC) and a Stirling engine which, by connecting to a seawater reverse osmosis desalination unit, provides fresh water. First, a parametric evaluation is performed to study the effect of some key parameters, including the current density and the working temperature of the FC and the thermal conductance between the working substance and the heat reservoirs in the Stirling engine, on the objective functions. The objective functions include the energy efficiency, the exergy destruction rate density, the fresh water production rate, and the ecological function density. After investigating each double combination of these objective functions, two scenarios are defined in quest to concurrently optimize three functions together. The first scenario aims to optimize the energy efficiency, the exergy destruction rate density, and the fresh water production rate; and the second scenario attempts to optimize the energy efficiency, the fresh water production rate, and the ecological function density. A multi‐objective evolutionary algorithm joined with the nondominated sorting genetic algorithm (NSGA‐II) approach is employed to obtain Pareto fronts in each case scenario. In order to ascertain final solutions between Pareto fronts, three fast and robust decision‐making methods are employed including TOPSIS, LINMAP, and Fuzzy. Finally, a sensitivity analysis is conducted to critically analyze the performance of the system.

Performance Optimizations with Single-, Bi-, Tri-, and Quadru-Objective for Irreversible Diesel Cycle

“…Ahmadi et al [ 40 , 41 , 42 , 43 ] carried out MOO for an irreversible radiant heat engine [ 40 ], fuel cell combined cycle [ 41 , 42 ], and Lenoir heat engine [ 43 ] with different objective functions. Shi et al [ 44 ] and Ahmadi et al [ 45 ] performed MOO of the Atkinson cycle when the working fluid’s specific heats were constants [ 44 ] and varied with temperature non-linearly [ 45 ].…”

Development of an Integrated Structure for the Tri-Generation of Power, Liquid Carbon Dioxide, and Medium Pressure Steam Using a Molten Carbonate Fuel Cell, a Dual Pressure Linde-Hampson Liquefaction Plant, and a Heat Recovery Steam Generator

“…To do so, they investigated several parameters of the integrated structure such as the flow density of the fuel cell, the gas turbine inlet temperature, and the effect of the heating part which transfers heat to the electricity generation cycle. Ahmadi et al [8] optimized a freshwater production hybrid structure by combining the MCFC, a Stirling engine, and reverse osmosis water desalination. They implemented two methods of optimization for analyzing and improving the performance of the developed system.…”

Integrated Ejector‐Based Flare Gas Recovery and On‐Site Desalination of Produced Water in Shale Gas Production

“…They also proposed a new process system for hydrogen and freshwater production. Recently, Ahmadi et al have investigated a hybrid cycle consisting of the molten carbonate fuel cell and a Stirling engine to generate freshwater from a seawater reverse osmosis (RO) desalination unit. Mohammadi et al also proposed a hybrid system composed of a gas turbine, an organic Rankine cycle (ORC) and an absorption refrigeration cycle as a combined cooling, heating and power system for producing hot water for residential usage.…”