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

Area of Science:

• Sustainable Energy Systems
• Thermodynamics and Energy Conversion
• Environmental Engineering

Background:

• Integrated energy systems offer efficient resource utilization.
• Proton exchange membrane fuel cells (PEM FCs) are key for clean electricity generation.
• Waste heat recovery is crucial for enhancing system efficiency.

Purpose of the Study:

• To optimally design a novel multi-generation system.
• To integrate PEM FC, Ejector Refrigeration Cycle (ERC), and Reverse Osmosis (RO) desalination.
• To maximize exergy efficiency and minimize total cost rate (TCR).

Main Methods:

• Design variables included operating temperature, pressure, and current density of the PEM FC, and ERC operating pressures.
• Exergy efficiency and TCR were used as objective functions for optimization.
• Genetic Algorithm (GA) was employed to extract the Pareto front.
• Performance evaluation of refrigerants R134a, R600, and R123 within the ERC.

Main Results:

• The optimal design point yielded an exergy efficiency of 70.2%.
• The total cost rate (TCR) at the optimal point was 1.78 S/h.
• Performance variations were observed based on the selected ERC refrigerant.

Conclusions:

• The developed multi-generation system effectively produces electricity, cooling, heating, and freshwater.
• The optimization process successfully identified a design point balancing exergy efficiency and cost.
• The study provides a framework for designing efficient and cost-effective integrated energy systems.