Comprehensive Energy Exergy Economic and Environmental Assessment of an Integrated Organic Rankine Cycle Solid Oxide Fuel Cell and Absorption Chiller System Fueled by Steam Reformed Natural Gas

Abstract

This research presents a thorough evaluation of an integrated system comprising a Solid Oxide Fuel Cell (SOFC), Organic Rankine Cycle (ORC), and Absorption Chiller (AC). The study employs ASPEN PLUS V10 to assess the system's energy, exergy, economic, and environmental performance. The Integrated SOFC-ORC-AC system offers trigeneration capabilities, generating electricity, cooling, and heating from a single fuel source. It demonstrates potential as an efficient and environmentally friendly energy generation method. The system can be fuelled by steam-reformed natural gas or renewable fuels like biogas or syngas. The SOFC, employing a solid electrolyte, facilitates an electrochemical reaction with hydrogen, producing electricity and heat. The exhaust gas further powers the ORC and AC units. The study builds a mathematical model, assuming steady-state, isothermal, and chemically equilibrated conditions. The SOFC and ORC simulations utilize the Peng Robinson model, while the LiBr absorption chiller employs the ELECNRTL property method for fluid thermodynamic properties. The SOFC electrical model was validated against real-world data, ensuring accuracy. The study also tested a single-effect LiBr absorption chiller, comparing results with experimental data. The operating pressure's effect on SOFC performance was evaluated, demonstrating reduced voltage losses and increased cell voltage and power density at higher pressures. Operating temperature elevation enhanced electrochemical reactions, resulting in higher cell voltage and power density, despite increased voltage losses. Augmenting the fuel utilization factor reduced voltage losses, leading to increased cell voltage and power density. The SOFC-ORC system efficiency peaked at 58.9% at the highest operating pressure, influenced by factors like compressor consumption and high fuel flow rate. Redirecting exhaust gas for waste heat recovery produced hot water, influencing the Coefficient of Performance (COP) of the LiBr absorption chiller. Mass flow rate had a smaller impact compared to hot water temperature. Exergy analysis revealed the SOFC's high efficiency (83.92%), while the steam turbine and LiBr absorption chiller demonstrated lower exergy efficiencies (70% and 32.6% respectively). Cost analysis indicated that the SOFC power plant was the most significant investment at 130,715 $, highlighting the long-term benefits of the integrated system in terms of high efficiency, low emissions, and fuel flexibility. This research offers a comprehensive assessment of the integrated SOFC-ORC-AC system, shedding light on its potential as an efficient and environmentally friendly energy generation solution. The study's findings contribute to the advancement of sustainable energy technologies, emphasizing the importance of trigeneration systems for future energy landscapes.