Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “fluidization”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

1,055 records · Page 59

Comprehensive Benchmark Suite for Simulation of Particle Laden Flows Using the Discrete Element Method with Performance Profiles from the Multiphase Flow with Interface eXchanges (MFiX) Code

Five benchmark problems are developed and simulated with the computational fluid dynamics and discrete element model code MFiX. The benchmark problems span dilute and dense regimes, consider statistically homogeneous and inhomogeneous (both clusters and bubbles) particle concentrations and a range of particle and fluid dynamic computational loads. Several variations of the benchmark problems are also discussed to extend the computational phase space to cover granular (particles only), bidisperse and heat transfer cases. A weak scaling analysis is performed for each benchmark problem and, in most cases, the scalability of the code appears reasonable up to approx. 103 cores. Profiling of the benchmark problems indicate that the most substantial computational time is being spent on particle-particle force calculations, drag force calculations and interpolating between discrete particle and continuum fields. Hardware performance analysis was also carried out showing significant Level 2 cache miss ratios and a rather low degree of vectorization. These results are intended to serve as a baseline for future developments to the code as well as a preliminary indicator of where to best focus performance optimizations.

97 MATHEMATICS AND COMPUTING↗

Operation of the NETL Chemical Looping Reactor with Natural Gas and a Novel Copper-Iron Material

As part of the U.S. Department of Energy’s Advanced Combustion Program, the National Energy Technology Laboratory’s Research and Innovation Center (NETL R&IC) is investigating the feasibility of a novel combustion concept in which the GHG emissions can be significantly reduced. This concept involves burning fuel and air without mixing these two reactants. If this concept is technically feasible, then CO 2 emissions can be significantly reduced at a much lower cost than more conventional approaches. This indirect combustion concept has been called Chemical Looping Combustion (CLC) because an intermediate material (i.e., a metaloxide) is continuously cycled to oxidize the fuel. This CLC concept is the focus of this research and will be described in more detail in the following sections.

01 COAL, LIGNITE, AND PEAT↗

Supercritical Carbon Dioxide (SCO 2 ) Cycle as an Efficiency Improvement Opportunity for Air-fired Coal Combustion

Coal has been historically the fuel to satisfy the United States’ need for baseload electricity generation. Increasingly stringent environmental regulations (specifically uncertainty for CO 2 emission regulations), are forcing the electric power industry to scrutinize the long-term viability of new and existing coal-fueled assets. The development of advanced, higher efficiency coal power generation technologies leading to reductions in CO 2 and other emissions and competitive costs are one avenue to address these concerns. A goal of this study was initially to identify one or more conceptual designs for a coal-fired power plant that could meet the existing “Carbon Pollution Standard (CPS) for New Power Plants” without dedicated CO 2 capture equipment. Since the EPA proposals are still under the review process, this report uses the current limits. Additional goals include: sCO 2 cycles systems that achievie an efficiency > 46.7 % HHV and a cost of electricity of < $82.3/MWh.

01 COAL, LIGNITE, AND PEAT↗

Economic Long-Duration Electricity Storage by Using Low-Cost Thermal Energy Storage and High-Efficiency Power Cycle (ENDURING)

The project involved considerable industry participation including General Electric (GE, power cycle analysis), Babcock & Wilcox (B&W), Allied Mineral Products (insulation materials), and Worley-Advisian (system integration). They provided insights on their products or services for component and system designs. The project successfully achieved the project goals of demonstrating technology feasibility for long duration energy storage with a technology path towards 5c/kWh levelized cost of storage. The project has generated four patent applications (one awarded patent and three under review), three published journal papers, a draft book chapter, and five manuscripts under preparation, with several conference papers and numerous presentations including invited talks. An intellectual properties (IP) option agreement has been signed with an U.S. manufacturer, with interests from energy developers. Four related projects with $5.5 million DOE funding support more developments for long duration energy storage and broad industry decarbonization.

25 ENERGY STORAGE↗

An Adaptive Timestepping Algorithm for Particle Time Integration in Coupled CFD-DEM Simulations

Coupled Computational Fluid Dynamics(CFD) - Discrete Element Method (DEM) models provide an accurate description of multiphase physical systems where a granular phase exists in an underlying continuous medium. The time integration of the granular phase in these simulations are typically handled using an explicit time integration scheme with a global time step that is much smaller than fluid time scales, in order to resolve inter-particle collisions. An adapative time integration technique that avoids this global constraint for the granular phase is presented in this work. The algorithm involves the use of a local time stepping approach to resolve collisional time scales for only a subset of particles that are in close proximity to potential collision partners, thereby resulting in substantial reduction of computational cost. This approach is observed to be 2-3X faster than traditional explicit methods for problems that involve both dense and dilute regions, while maintaining the same level of accuracy.

97 MATHEMATICS AND COMPUTING↗

Pilot-Scale CFP Commissioning: Creative Problem Solving and Lessons Learned

We have commissioned a pilot-scale, ex-situ catalytic fast pyrolysis (CFP) reactor system in the Thermal and Catalytic Process Development Unit (TCPDU) at the National Renewable Energy Laboratory. The FCC-style CFP system, including a riser and continuous regeneration, was added to the existing half-ton-per-day biomass fast pyrolysis unit and was designed to run a zeolite-type catalyst. The system is unique due to its scale and catalyst flow control scheme. As the design of this system was informed by early data from a bench-scale reactor, several technical scale-up challenges had to be overcome. Additionally, physical constraints and the complexities of biomass vapors required and inspired creative solutions. This talk will discuss the specific challenges we found and addressed, including an oxygen deficiency in the regenerator and plugging in the exit streams. We explored several options for increasing oxygen availability and selected a cyclone-catalyst return design on the exit line so we could increase air flow through the regenerator. We found that hot gas filtration is essential in any exit streams containing water vapor and trace amounts of catalyst; any combination of catalyst and condensate quickly makes mud that plugs equipment and severely limits run time. Duplicate filters are also required to extend run time. Most of the equipment and solutions were designed and installed by our team of engineers and technicians, working closely together in an iterative process to design, install, operate, then redesign. Collaborations with other national laboratories with computational fluid dynamics expertise helped inform designs and identify creative solutions to these scale-up challenges. Ultimately, data from the reactor system will be used to validate a comprehensive kinetic model of CFP that can be used to better design and inform new systems at various scales.

09 BIOMASS FUELS↗