The feasibility study of cascade waste heat recovery in a molten carbonate fuel cell-driven system

Abstract

The use of solid-state converters in power production, particularly in combination with molten carbonate fuel cells, holds promise for improving overall power generation efficiency. These systems are designed to capture and utilize the considerable waste heat generated during power production, leading to enhanced performance and energy recovery. The specific approach discussed in this investigation involves a solid-state system consisting of an alkali metal thermal electric converter and a thermally regenerative electrochemical cycle for waste heat recovery and additional power generation. The study conducts a comprehensive analysis of this combined system, focusing on various aspects, including energy, exergy, and economic considerations. One key variable investigated is the current density, which plays a significant role in determining system performance. The investigation considers sensitivity analysis by varying six design parameters, offering insights into how different factors affect the system's performance. One of the notable findings is the identification of the overall maximum power density, which reaches 2642 W/m2 at a specific current density of 4686 A/m2. Evaluating the overall performance of the system, the study reports energetic efficiency, exergetic efficiency, and exergy destruction rate density. The energetic efficiency stands at approximately 44.04 %, while the exergetic efficiency is notably higher at 47.09 %. Additionally, the exergy destruction rate density is reported at 2968 W/m2. The research highlights the significance of the operating temperature of the molten carbonate fuel cell, as it has a substantial impact on the overall performance of the system. Increasing the operating temperature of the fuel cell leads to improvements in system efficiency and performance. In summary, the investigation demonstrates the potential of a solid-state system with waste heat recovery components in combination with a molten carbonate fuel cell. This approach enhances power production efficiency, making it a promising solution for sustainable and efficient energy generation.