Multiobjective optimization and performance assessment of a PEM fuel cell-based energy system for multiple products.

In this article, the optimal design of a novel multi-generation system for the production of electricity, cooling, heat and freshwater is discussed. In this system, a Proton exchange membrane fuel cell (PEM FC) is used to generate electricity, and the heat produced by it is absorbed by the Ejector Refrigeration Cycle (ERC) and used to provide cooling and heating capacity. A reverse osmosis (RO) desalination system is also used to supply freshwater. The esign variables in this research are operating temperature and pressure and current density of FC, as well as the operating pressure of the HRVG, evaporator, and condenser of the ERC system. In order to optimize the considered system, the exergy efficiency and total cost rate (TCR) of the system are considered as optimization objective functions. To this end, the genetic algorithm (GA) is used and the Pareto front is extracted. Also, three refrigerants R134a, R600 and R123 areused as ERC system refrigerant and their performance are evaluated. Finally, the optimal design point is selected. At the mentioned point, the exergy efficiency is 70.2% and the TCR of the system is 1.78 S/h.

Multidisiplinary design optimization of a power generation system based on waste energy recovery from an internal combustion engine using organic Rankine cycle and thermoelectric generator.

The research paper mainly deals with waste heat recovery from internal combustion engines (ICE) using the organic Rankine cycle (ORC) and Thermoelectric generator (TEG). Simultaneously recovering the wasted heat of both exhaust gases and coolant, a novel configuration named two-stage is proposed. Then a comprehensive thermo-economic analysis and optimization are conducted. Produced power and total cost rate are selected as the objective function of the optimization. Also, the first and second stage pressures of the ORC system are considered as decision variables. Finally, a sensitivity analysis is performed to study the effect of expander inlet temperature, pumps isentropic efficiency, and expander isentropic efficiency on the objective function.