Performance analysis of a fuel cells integrated system utilizing Liquified Natural Gas as fuel for a green shipping target

Abstract

In this study, a system integrating Solid Oxide Fuel Cells (SOFC) fueled by Liquefied Natural Gas (LNG) for marine vessels is proposed and analyzed. The system comprises Proton Exchange Membrane Fuel Cells (PEMFC), Organic Rankine Cycle (ORC), Gas Turbine (GT), Steam Rankine Cycle (SRC), and Waste Heat Boiler (WHB) combined with the SOFC system to enhance power generation and system performance. The PEMFC is particularly important for maritime applications, compensating for the disadvantage of the SOFC in terms of starting and response time according to the vessel's demand. The CO2 capture system designated in this proposal not only helps to comply with international regulations and standards on emission control but also reduces the power consumption requirement for traditional CO2 capture. To simulate and optimize the system's design, the Aspen HYSYS V12.1 process modelling software is employed. The thermodynamic models and equations for this proposed system are based on the first and second laws of thermodynamics. The exergy destruction equations and calculations for the main components are established and estimated to optimize the system's design and operation. The predicted performance of the proposed system is 68.76% for energy efficiency and 33.58% for exergy efficiency. The combined system for cold energy utilization and waste heat recovery generates more than 2100.42 kW equivalent, representing 35.6% of the total system generation. The results of the analysis indicate that when the current density is increased from 930 to 1930 A/m2, performance of system experience a reduction of 33.18% and 16.2% for the energy and exergy efficiencies, respectively.

Keywords

• LNG
• SOFC
• CO2 cryogenic capture
• Cold energy utilization
• Waste heat recovery