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Linear Extrusion 400 Tons/Day Dry Solids Pump

Description: Pratt & Whitney Rocketdyne (PWR) has developed an innovative gasifier concept that uses rocket engine experience to significantly improve gasifier performance, life, and cost compared to current state-of-the-art systems. The PWR gasifier concept uses a compact and highly efficient (>50%) dry solids pump that has excellent availability (>99.5%). PWR is currently developing this dry solids pump under a U.S. Department of Energy (DOE) cooperative agreement. The conceptual design on two dry solids pumps were completed under this agreement and one pump concept was selected for preliminary design. A preliminary design review (PDR) of the selected pump was presented on September 20, 2007 to PWR management and numerous technical specialists. Feedback from the PDR review team has been factored into the design and a Delta-PDR was held on April 9, 2008.
Date: April 30, 2008
Creator: Sprouse, Kenneth & Matthews, David
Partner: UNT Libraries Government Documents Department

Quasi-Three Dimensional Experiments on Liquid-Solid Fluidized Bed of Three Different Particles in Two Different Distributors

Description: This thesis is an experimental study of the fluidization of binary mixture in particulate flows. A fluidized bed with two distributors was built with water being used as carrying fluid. Three types of solid particles of nylon, glass and aluminum of the same size and different densities are used in the experiments. The wall effect on a single particle fluidization, the fluidization of binary mixture of large density difference (nylon and aluminum of density ratio of 0.42), and the fluidization of binary mixture of close density (glass and aluminum with density ratio of 0.91) were investigated. Also, the effect of distributors on mono-disperse and bi-disperse particle fluidization was investigated. Results show that the presence of narrow walls reduces the minimum fluidization velocity for a single particle by as much as nearly 40%. Also, in the case of binary mixture of close density particles, uniform mixing was easily achieved and no segregation was observed, but in the case of large density difference particles, there exists significant segregation and separation. At high velocity, the uniform distributor behaves like a transport bed. To achieve a full bed in the single jet, it requires 1.5 times velocity of the uniform distributor. This behavior determines their application in the industries.
Date: December 2009
Creator: Obuseh, Chukwuyem Charles
Partner: UNT Libraries

Studies of granular flow down an inclined chute. Final technical report

Description: An inclined chute facility and its associated diagnostics has been developed and utilized to study the flow of granular materials. A variety of flow regimes and flow phenomena were observed. Fully developed flows were observed over a bumpy base for a range of slopes. Under some conditions, these flows were dominated by friction and under other conditions, collisions played a dominant role. A variety of unsteady flows were also observed. These include decelerating flows, accelerating flows, and wavy (periodic) flows. The characteristics of the base strongly influenced the flow regime and flow dynamics.
Date: June 1, 1996
Creator: Hanes, D.M.
Partner: UNT Libraries Government Documents Department

A theoretical and numerical study of the flow of granular materials. Quarterly report, April 1, 1992--June 30, 1992

Description: Linearized stability equations for flow of granular materials down an inclined plane are derived for a continuum model [cf. Goodman and Cowin (1971), Rajagopal and Massoudi (1990)]. The basic flow exhibits multiplicity of solutions, one in which the volume fraction increases monotonically from the inclined plane to the free surface, and the other in which the volume fraction increases monotonically. Solutions to the basic equations were presented in the previous report. Next, we have to solve the stability equations, numerically.
Date: December 31, 1992
Creator: Rajagopal, K.R.
Partner: UNT Libraries Government Documents Department

Nuclear mgnetic resonance study of granular flows. Final report

Description: We have demonstrated the efficacy of NMRI to granular flow studies of objects that yield NMR signals (seeds, pharmaceutical pills) in confined spaces (rotating cylinders, shaking boxes). Excellent results for velocity and concentration of flowing and colliding particles have been obtained non-invasively. We studied flows in geometries that are otherwise impossible to study because of the optical opacity of the materials. In addition, we obtained data for diffusion and collisional losses which must be related to granular temperature. We also measured the global collisional and frictional energy loss for a rotating cylinder containing granular material and compared it to that obtained from the NMRI velocity and acceleration data. We used the same NMR technique to study the interplay between radial and axial segregation of heterogeneous particles in a partially filled rotating cylinder. We also measured flow and diffusion of vibrating particles in the NMRI apparatus to ascertain that such experiments are, indeed, possible. Some theoretical studies were initiated to explain some of the velocity profiles and free surface shapes of rotating drum flow. A direct numerical simulation of the drum flow successfully predicted a number of features, including velocity, concentration, and dissipation profiles in rotating cylinders.
Date: March 1, 1995
Partner: UNT Libraries Government Documents Department

Gravity-driven dense granular flows

Description: The authors report and analyze the results of numerical studies of dense granular flows in two and three dimensions, using both linear damped springs and Hertzian force laws between particles. Chute flow generically produces a constant density profile that satisfies scaling relations suggestive of a Bagnold grain inertia regime. The type for force law has little impact on the behavior of the system. Failure is not initiated at the surface, consistent with the absence of surface flows and different principal stress directions at vs. below the surface.
Date: March 29, 2000
Partner: UNT Libraries Government Documents Department

Effect of finite particle interaction time in granular systems

Description: Almost all previously published theoretical papers that propose constitutive relations for granular flows use some form of kinetic theory, which neglects effects of finite particle interaction time and multiparticle interactions. In dense systems, these effects contain essential physics and determine the evolution of the stress system in granular flows. In this paper, the authors shall demonstrate the importance of these effects and study the behavior of the granular stress in a dense system. The particle interaction time is a random variable in a granular system, and they show that its probability distribution obeys an exponential law. The temporal decay of this probability represents the destruction of contacts between particles and is related to the relaxation of the collisional stress in a granular system. By considering the balance between creation and destruction of contacts, they derive a constitutive relation for collisional stress. Depending on the form of the model chosen to approximate forces developed during particle interactions, the constitutive relation can predict either viscoelastic or viscoplastic behavior of the collisional stress. Numerical simulations are performed to verify the theoretical findings and to study further the properties of dense granular systems.
Date: July 1, 1998
Creator: Zhang, D.Z. & Rauenzahn, R.M.
Partner: UNT Libraries Government Documents Department

Experimental investigation of vibration-induced bulk solids transport and segregation. Quarterly technical progress report, April--June 1995

Description: In the first phase of this research, we have finished the simulation studies to support the experimental work in the area of particle transport in vibrated granular beds. Representative results are briefly summarized in the attached short paper. Based on the results obtained, in particular the interesting phenomena such as heaping, arching and bifurcation in the flow regime, we have decided to carry put the initial set of experiments in a two dimensional rectangular bed. A schematic diagram of this is also attached. This rectangular cell will allow us to make the necessary observations, in particular the optical observations made through the use of Kodak EkatPro1000 high-speed video camera. A student, supported by the Institute as a match to this grant is in tile process of completing the fabrication of this cell, and has collected all the pertinent literature in this area. We have also obtained specifications and quotations for the vibration unit to be used in this experiments, and it will be ordered in the near future. In addition to the use of the two dimensional rectangular bed, we have also developed a three dimensional cylindrical cell for the study of segregation behavior. A nonintrusive tracking system will be used in measuring the trajectories of tile rising large particle, and at present all the calibration jigs, and software have been developed. We anticipate collecting the experimental data in the next few weeks.
Date: May 1, 1996
Creator: Rosato, A.D. & Dave, R.N.
Partner: UNT Libraries Government Documents Department

A theoretical and numerical study of the flow of granular materials down an inclined plane. Final report

Description: The mechanics of the flowing granular materials such as coal, agricultural products, at deal of attention as it has fertilizers, dry chemicals, metal ores, etc. have received a great deal of attention as it has relevance to several important technological problems. Despite wide interest and more than five decades of experimental and theoretical investigations, most aspects of the behavior of flowing granular materials are still not well understood. So Experiments have to be devised which quantify and describe the non-linear behavior of the modular materials, and theories developed which can explain the experimentally observed facts. As many models have been suggested for describing the behavior of granular materials, from both continuum and kinetic theory viewpoints, we proposed to investigate the validity and usefulness of representative models from both the continuum and kinetic theory points of view, by determining the prediction of such a theory, in a representative flow, with respect to existence, non-existence, multiplicity and stability of solutions. The continuum model to be investigated is an outgrowth of a model due to Goodman and Cowin (1971, 1972) and the kinetic theory models being those due to Jenkins and Richman (1985) and Boyle and Massoudi (1989). In this report we present detailed results regarding the same. Interestingly, we find that the predictions of all the theories, in certain parameter space associated with these models, are qualitatively similar. This ofcourse depends on the values assumed for various material parameters in the models, which as yet are unknown, as reliable experiments have not been carried out as yet for their determination.
Date: December 1995
Creator: Rajagopal, K. R.
Partner: UNT Libraries Government Documents Department

Dense inclined flows: Theory and experiments. Quarterly technical progress report, January 1, 1995--March 31, 1995

Description: Rapid, gravity-driven flows of granular materials down inclines pose a challenge to our understanding. Even in situations in which the flow is steady and two-dimensional, the details of how momentum and energy are balanced within the flow and at the bottom boundary are not well understood. Thus we have undertaken a research program integrating theory, computer simulation, and experiment that will focus on dense entry flows down inclines. The effort involves the development of theory informed by the results of simultaneous computer simulations and the construction, instrumentation, and use of an experimental facility in which the variables necessary to assess the success or failure of the theory can be measured. In the present reporting period, we have continued a series of measurements in the chute facility with a flat, frictional boundary. At several inclinations between 15.5{degrees} and 20{degrees}, and at several gate openings for each angle, we have measured mass flow rate and mass holdup, as well as granular temperature and collision frequency at the bottom wall of the chute. By recording simultaneously the collisional normal stress at the bottom wall and the mass holdup above it, the experiments reveal the fraction of the weight of particles that is supported by direct impact.
Date: August 1, 1995
Creator: Jenkins, J.T. & Louge, M.Y.
Partner: UNT Libraries Government Documents Department

Development of Millimeter-Wave Velocimetry and Acoustic Time-of-Flight Tomography for Measurements in Densely Loaded Gas-Solid Riser Flow

Description: The MFDRC was formed in 1998 to advance the state-of-the-art in simulating multiphase turbulent flows by developing advanced computational models for gas-solid flows that are experimentally validated over a wide range of industrially relevant conditions. The goal was to transfer the resulting validated models to interested US commercial CFD software vendors, who would then propagate the models as part of new code versions to their customers in the US chemical industry. Since the lack of detailed data sets at industrially relevant conditions is the major roadblock to developing and validating multiphase turbulence models, a significant component of the work involved flow measurements on an industrial-scale riser contributed by Westinghouse, which was subsequently installed at SNL. Model comparisons were performed against these datasets by LANL. A parallel Office of Industrial Technology (OIT) project within the consortium made similar comparisons between riser measurements and models at NETL. Measured flow quantities of interest included volume fraction, velocity, and velocity-fluctuation profiles for both gas and solid phases at various locations in the riser. Some additional techniques were required for these measurements beyond what was currently available. PNNL’s role on the project was to work with the SNL experimental team to develop and test two new measurement techniques, acoustic tomography and millimeter-wave velocimetry. Acoustic tomography is a promising technique for gas-solid flow measurements in risers and PNNL has substantial related experience in this area. PNNL is also active in developing millimeter wave imaging techniques, and this technology presents an additional approach to make desired measurements. PNNL supported the advanced diagnostics development part of this project by evaluating these techniques and then by adapting and developing the selected technology to bulk gas-solids flows and by implementing them for testing in the SNL riser testbed.
Date: April 1, 2007
Creator: Fort, James A.; Pfund, David M.; Sheen, David M.; Pappas, Richard A. & Morgen, Gerald P.
Partner: UNT Libraries Government Documents Department

The effect of inter-particle contact time in granular flows -- A network theory

Description: In a kinetic theory, it is usually assumed that the time duration of particle collision is vanishingly small and only binary collisions are considered. The validity of these assumptions depends on the ratio of collision time to mean free flight time. If this ratio is small, the kinetic theory description is appropriate. In a dense system, however, this ratio is usually large, and the dynamics of the multi-particle interactions have to be considered. For instance, during a collision, the contacting pair usually has a relative tangential velocity that causes a change in the direction of rebound. This implies a dependence of the granular stress on the vorticity of the mean flows field. Due to the inherent energy dissipation in a particle collision, and the consistent rearrangement of particles, there are relaxation times associated with them. In a binary collision, this energy dissipation is represented by coefficient of restitution. In a dense granular system, multi-particle interactions occur frequently. The energy dissipation and system relaxation have to be studied by the consideration of the dynamics in the duration of particle interaction and cannot be represented by a single coefficient of restitution. In this case, the relaxation times must be introduced explicitly. By modification of the network theory for rubber material, a constitutive model for dense granular material is developed based on the dynamics of multi-particle interaction. The finite particle interaction time and system relaxation times are considered.
Date: December 31, 1996
Creator: Zhang, D.Z. & Rauenzahn, R.M.
Partner: UNT Libraries Government Documents Department


Description: The objective of this project is to demonstrate proof of principal to feed and meter granular coal into 450 psig gas pressure for use with pressurized fluidized bed combustors. This report summarizes work undertaken in the first quarter of 2000 in support of that objective. At the end of the last quarter the pump had been re-designed to incorporate a larger torque hub and provide a substantial increase in drive train strength to prevent recurrence of failures experienced during earlier testing. Additional modifications were incorporated to improve the performance of the disk seals by improved location and adjustability, and the outlet was modified to incorporate a method to allow rapid adjustment of the outlet sealing column length without pump disassembly and rework being required. This quarter has been largely spent in manufacture of the new parts required, and in initial assembly, alignment and pinning of the revised configuration. The assembly is now complete and the pump is ready for installation into the test rig for the final series of tests.
Date: April 1, 2000
Creator: Aldred, Derek L.
Partner: UNT Libraries Government Documents Department

Experimental investigation of vibration-induced bulk solids transport and segregation. Final technical report, March 28, 1995--September 26, 1996

Description: We report experiments on the rise time T of a single large sphere within a sinusoidally vibrated bed (amplitude a) of uniform particles (diameter d). At fixed acceleration, three distinct behavioral regimes are identified both from visual observations and from the typical increase of T with frequency f. Two convective regimes separated by a critical frequency are found, and for low a and high f, a {open_quotes}non-convective{close_quotes} regime. In the latter, the bed crystallizes and a size dependent rise is evidenced. The relevance of the non-dimensional parameter a/d is shown and a scaling law is deduced which has the form f {proportional_to} d{sup {minus}1/2}
Date: January 12, 1997
Creator: Plasynski, S.; Rosato, A.D. & Dave, R.N.
Partner: UNT Libraries Government Documents Department

Wet solids flow enhancemant

Description: WE used glass beads of different sizes as.a model system to study the flow enhancing properties of Octadecyltrichlorosilane (OTS). 0TS provides Si(CH{sub 2}){sub 17}CH{sub 3} groups that bind with the surface hydrox groups to make it hydrophobic. Experimental data showed, indeed, that surface hydrophobicity promotes the flow of wet granular materials. Mixtures of different percentage of silanized/unsilanized particles were prepared for tensile strength measurements. The tensile strength decreased as more silanized particles were added to the samples. The relationship between dimensionless tensile strength and void fraction followed the correlation found by Pierrat (1994). Contact angles were larger for the silanized particles, as compared with unsilanized ones.
Date: December 31, 1996
Creator: Caram, H.S.; Foster, N. & Wildman, D.J.
Partner: UNT Libraries Government Documents Department

Experiments using non-intrusive particle tracing techniques for granular chute flows. Final report

Description: The objective of this contract was to develop a system capable of non-intrusively tracking the motion of an individual particle for the study of granular flows down inclined chutes. The result of the project is a system capable of following the three-dimensional translational and rotational motion of an individual particle embedded with a flowing granular material. The basic system consists of a sphere embedded with three orthogonal transmitters emitting at different frequencies which induce voltages in an antenna array surrounding the flow regime. Analysis of the induced voltage signals within the framework of a derived model yields both the position and orientation of the sphere. Tests were performed in a small scale model chute as well as in a cylindrical vibrated granular bed, which clearly demonstrates the capability of the system. As a result of discussions at meetings held semi-annually for the Granular Flow Advanced Research Objectives (GFARO) contractors, it was deemed necessary to pursue an additional experimental program as part of this contract related to the measurement of sphere collision properties. The outcome of the work (reported in Appendix C) is the determination of certain properties which are needed for use in computer simulations and theory.
Date: December 31, 1998
Creator: Rosato, A.D.; Dave, R.N. & Fischer, I.S.
Partner: UNT Libraries Government Documents Department

Two-phase potential flow. Final report, September 1, 1988--March 31, 1999

Description: The objective of this work was to devise essentially exact solutions to a set of well-defined basic problems of inviscid fluid flow with particulate inclusions. This would help to establish a sound basis for fundamental theoretical developments in the field of two-phase flow. The results of this effort have ranged from basic theorems and the formulation of conservation laws for two-phase mixtures, to detailed predictions for specific geometrical patterns and experimental confirmation of these results.
Date: July 1, 1999
Creator: Wallis, G.B.
Partner: UNT Libraries Government Documents Department

Advanced material distribution measurement in multiphase flows: A case study

Description: A variety of tomographic techniques that have been applied to multiphase flows are described. The methods discussed include electrical impedance tomography (EIT), magnetic resonance imaging (MRI), positron emission tomography (PET), gamma-densitometry tomography (GDT), radiative particle tracking (RDT), X-ray imaging, and acoustic tomography. Also presented is a case study in which measurements were made with EIT and GDT in two-phase flows. Both solid-liquid and gas-liquid flows were examined. EIT and GDT were applied independently to predict mean and spatially resolved phase volume fractions. The results from the two systems compared well.
Date: August 1, 1998
Creator: George, D.L.; Ceccio, S.L.; O`Hern, T.J.; Shollenberger, K.A. & Torczynski, J.R.
Partner: UNT Libraries Government Documents Department

Spatiotemporal dynamics of a shallow fluidized bed.

Description: An experimental and theoretical study of the dynamics of an air-fluidized thin granular layer is presented. Near the threshold of instability, the system exhibits critical behavior with remarkably long transient dynamics. Above the threshold of fluidization the system undergoes a Hopf bifurcation as the layer starts to oscillate at a certain frequency due to a feedback between the layer dilation and the airflow rate. Based on our experimental data, we formulate a the simple dynamical model which describes the transition in a shallow fluidized bed.
Date: December 5, 2000
Creator: Aranson, I. S.; Tsimring, L. S. & Clark, D. K.
Partner: UNT Libraries Government Documents Department


Description: The objective was to visualize the flow of granular materials in flat bottomed silo. This was done by for dry materials introducing mustard seeds and poppy seeds as tracer particles and imaging them using Nuclear Magnetic Resonance. The region sampled was a cylinder 25 mm in diameter and 40 mm in length. Eight slices containing 128*128 to 256*256 pixels were generated for each image. The size of the silo was limited by the size of the high resolution NMR imager available. Cross-sections of 150mm flat bottomed silos, with the tracer layers immobilized by a gel, showed similar qualitative patterns for both dry and wet granular solids.
Date: March 31, 1997
Creator: Caram, Hugo S. & Foster, Natalie
Partner: UNT Libraries Government Documents Department


Description: The strain-stress behavior of a wet granular media was measured using a split Parfitt tensile tester. In all cases the stress increases linearly with distance until the maximum uniaxial tensile stress is reached. The stress then decreases exponentially with distance after this maximum is reached. The linear region indicates that wet solids behave elastically for stresses below the tensile stresses and can store significant elastic energy. The elastic deformation cannot be explained by analyzing the behavior of individual capillary bridges and requires accounting for the deformation of the solids particles. The elastic modulus of the wet granular material remains unexplained.
Date: July 1, 1999
Creator: Caram, Hugo S. & Foster, Natalie
Partner: UNT Libraries Government Documents Department