Compact, Lightweight Adsorber and Sabatier Reactor for CO2 Capture and Reduction for Consumable and Propellant Production
The utilization of CO2 to produce (or recycle) life support consumables, such as O2 and H2O, and to generate propellant fuels is an important aspect of NASA’s concept for future, long duration planetary exploration. One potential approach is to capture and use CO2 from the Martian atmosphere to generate the consumables and propellant fuels. Precision Combustion, Inc. (PCI), with support from NASA, continues to develop its regenerable adsorber technology for capturing CO2 from gaseous atmospheres (for cabin atmosphere revitalization and in-situ resource utilization applications) and its Sabatier reactor for converting CO2 to methane and water. Both technologies are based on PCI’s Microlith ® substrates and have been demonstrated to reduce size, weight, and power consumption during CO2 capture and methanation process. For adsorber applications, the Microlith substrates offer a unique resistive heating capability that shows potential for short regeneration time and reduced power requirements compared to conventional systems. For the Sabatier applications, the combination of the Microlith substrates and durable catalyst coating permits efficient CO2 methanation that favors high reactant conversion, high selectivity, and durability. Results from performance testing at various operating conditions will be presented. An effort to optimize the Sabatier reactor and to develop a bench-top Sabatier Development Unit (SDU) will be discussed. Nomenclature
Lessons Learned from the Development and Implementation of the Atmosphere Resource Recovery and Environmental Monitoring Project
The Advanced Exploration Systems (AES) Program's Atmosphere Resource Recovery and Environmental Monitoring (ARREM) Project have been developing atmosphere revitalization and environmental monitoring subsystem architectures suitable for enabling sustained crewed exploration missions beyond low Earth orbit (LEO). Using the International Space Station state-of-the-art (SOA) as the technical basis, the ARREM Project has contributed to technical advances that improve affordability, reliability, and functional efficiency while reducing dependence on a ground-based logistics resupply model. Functional demonstrations have merged new process technologies and concepts with existing ISS developmental hardware and operate them in a controlled environment simulating various crew metabolic loads. The ARREM Project's strengths include access to a full complement of existing developmental hardware that perform all the core atmosphere revitalization functions, unique testing facilities to evaluate subsystem performance, and a coordinated partnering effort among six NASA field centers and industry partners to provide the innovative expertise necessary to succeed. A project overview is provided and the project management strategies that have enabled a multidiscipinary engineering team to work efficiently across project, NASA field center, and industry boundaries to achieve the project's technical goals are discussed. Lessons learned and best practices relating to the project are presented and discussed.
Comminution of carbons in fluidized bed combustion
Abstract The study surveys fifteen years of research on carbon comminution in bubbling fluidized bed combustors. It is carried out on the premise that comminution can be seen as the result of at least four phenomena occurring in series-parallel with each other and with combustion, namely: the primary fragmentation of coals or other carbonaceous materials, the secondary fragmentation, the fragmentation by uniform percolation and the attrition of chars, cokes and graphite. In combination with combustion, these phenomena control size reduction of feed carbon particles into fines of elutriable size and, as a consequence, combustion efficiency and particulate emissions. Information on fragmentation and attrition behaviour is conveniently obtained by means of laboratory and pre-pilot scale combustors when carbon is charged batchwise to the bed. Some of the literature data separately reported in the paper for each of the four phenomena taken into consideration can be used, as they are, or after appropriate modification, in the design of larger units. To this end, submodels directed to extrapolate comminution data beyond the ranges of experimental conditions in which they have been determined are thoroughly examined. The paper also discusses how comminution parameters are embodied into the equation model of bubbling fluidized bed combustors. The starting point is the carbon particle population balance. Depending on whether secondary fragmentation is or is not relevant, the population balance is expressed by means of an integro-differential or an ordinary differential equation. Reference is also made to a simplified model which contains essential comminution effects and adequately describes the performance of combustors charged with coals of different rank.