Simulation of Dynamic Operation and Coke-Based Degradation for SOFC-GT-Powered Medium and Long Haul Locomotives.

摘要

Movement of goods throughout the United States is often achieved via diesel-fueled rail power, among a multitude of available transportation methods. Accomplishing this task is often at the expense of individual and environmental health. This investigation develops an understanding of the potential for utilizing an SOFC-GT system in the locomotive application to replace the conventional diesel engine. The goals of utilizing such a system are to substantially reduce fuel consumption, CO2, PM, and NOx emission, and noise levels. These changes would potentially improve the health, environment, and livelihood of those who live near rail-based operations and are burdened with a disproportionate share of these negative effects. This understanding is developed through consideration of the system's physical constraints as well as projections of its operational capability. A first principles-based dynamic, spatially-resolved simulation model was developed in FORTRAN to study the performance capabilities, requirements, and limitations of the SOFC-GT system when operating along a representative long-haul path in the area of the South Coast Air Basin. Simulations analyzed the system performance for diesel fuel, natural gas, and hydrogen as potential near-term, transitional, and long-term fuels. Experimentation and dynamic modeling were utilized to develop a description of the expected amount of degradation within the fuel cell due to the deposition of carbon. This study concludes that the potential exists for an SOFC-GT system to be fully capable of replacing the conventional diesel engine onboard locomotives. Of particular note, a system integrating a diesel reformer onboard, which allows for the most seamless integration with current operations, could have an efficiency of 52.2%, save 30.3% of CO2, and reduce NOx by 97.7%. A similar system operating on natural gas would exhibit 60% efficiency, 53.8% CO2 savings, and the same NOx savings. For either system, water management considerations may require careful system design and packaging. Unmitigated carbon-related degradation was predicted to be severe, completely deactivating the SOFC in under 300 hours. Simulation of a mitigation strategy like an anode barrier layer predicted complete deactivation after greater than 4000 hours, indicating that an estimated 100 anode regeneration cycles over a 100,000 hour lifetime may be sufficient.