WorldWideScience

Sample records for model receives fuel

  1. Combustion system for hybrid solar fossil fuel receiver

    Science.gov (United States)

    Mehos, Mark S.; Anselmo, Kenneth M.; Moreno, James B.; Andraka, Charles E.; Rawlinson, K. Scott; Corey, John; Bohn, Mark S.

    2004-05-25

    A combustion system for a hybrid solar receiver comprises a pre-mixer which combines air and fuel to form an air-fuel mixture. The mixture is introduced tangentially into a cooling jacket. A burner plenum is fluidically connected to the cooling jacket such that the burner plenum and the cooling jacket are arranged in thermal contact with one another. The air-fuel mixture flows through the cooling jacket cooling the burner plenum to reduce pre-ignition of the air-fuel mixture in the burner plenum. A combustion chamber is operatively associated with and open to the burner plenum to receive the air-fuel mixture from the burner plenum. An igniter is operatively positioned in the combustion chamber to combust the air-fuel mixture, releasing heat. A recuperator is operatively associated with the burner plenum and the combustion chamber and pre-heats the air-fuel mixture in the burner plenum with heat from the combustion chamber. A heat-exchanger is operatively associated and in thermal contact with the combustion chamber. The heat-exchanger provides heat for the hybrid solar receiver.

  2. Mathematical modeling of polymer electrolyte fuel cells

    Science.gov (United States)

    Sousa, Ruy; Gonzalez, Ernesto R.

    Fuel cells with a polymer electrolyte membrane have been receiving more and more attention. Modeling plays an important role in the development of fuel cells. In this paper, the state-of-the-art regarding modeling of fuel cells with a polymer electrolyte membrane is reviewed. Modeling has allowed detailed studies concerning the development of these cells, e.g. in discussing the electrocatalysis of the reactions and the design of water-management schemes to cope with membrane dehydration. Two-dimensional models have been used to represent reality, but three-dimensional models can cope with some important additional aspects. Consideration of two-phase transport in the air cathode of a proton exchange membrane fuel cell seems to be very appropriate. Most fuel cells use hydrogen as a fuel. Besides safety concerns, there are problems associated with production, storage and distribution of this fuel. Methanol, as a liquid fuel, can be the solution to these problems and direct methanol fuel cells (DMFCs) are attractive for several applications. Mass transport is a factor that may limit the performance of the cell. Adsorption steps may be coupled to Tafel kinetics to describe methanol oxidation and methanol crossover must also be taken into account. Extending the two-phase approach to the DMFC modeling is a recent, important point.

  3. Thermal resistance model for CSP central receivers

    Science.gov (United States)

    de Meyer, O. A. J.; Dinter, F.; Govender, S.

    2016-05-01

    The receiver design and heliostat field aiming strategy play a vital role in the heat transfer efficiency of the receiver. In molten salt external receivers, the common operating temperature of the heat transfer fluid or molten salt ranges between 285°C to 565°C. The optimum output temperature of 565°C is achieved by adjusting the mass flow rate of the molten salt through the receiver. The reflected solar radiation onto the receiver contributes to the temperature rise in the molten salt by means of heat transfer. By investigating published work on molten salt external receiver operating temperatures, corresponding receiver tube surface temperatures and heat losses, a model has been developed to obtain a detailed thermographic representation of the receiver. The steady state model uses a receiver flux map as input to determine: i) heat transfer fluid mass flow rate through the receiver to obtain the desired molten salt output temperature of 565°C, ii) receiver surface temperatures iii) receiver tube temperatures iv) receiver efficiency v) pressure drop across the receiver and vi) corresponding tube strain per panel.

  4. Modeling: driving fuel cells

    Directory of Open Access Journals (Sweden)

    Michael Francis

    2002-05-01

    Fuel cells were invented in 1839 by Sir William Grove, a Welsh judge and gentleman scientist, as a result of his experiments on the electrolysis of water. To put it simply, fuel cells are electrochemical devices that take hydrogen gas from fuel, combine it with oxygen from the air, and generate electricity and heat, with water as the only by-product.

  5. Astronomical Receiver Modelling Using Scattering Matrices

    CERN Document Server

    King, O G; Copley, C; Davis, R J; Leahy, J P; Leech, J; Muchovej, S J C; Pearson, T J; Taylor, Angela C

    2014-01-01

    Proper modelling of astronomical receivers is vital: it describes the systematic errors in the raw data, guides the receiver design process, and assists data calibration. In this paper we describe a method of analytically modelling the full signal and noise behaviour of arbitrarily complex radio receivers. We use electrical scattering matrices to describe the signal behaviour of individual components in the receiver, and noise correlation matrices to describe their noise behaviour. These are combined to produce the full receiver model. We apply this approach to a specified receiver architecture: a hybrid of a continous comparison radiometer and correlation polarimeter designed for the C-Band All-Sky Survey. We produce analytic descriptions of the receiver Mueller matrix and noise temperature, and discuss how imperfections in crucial components affect the raw data. Many of the conclusions drawn are generally applicable to correlation polarimeters and continuous comparison radiometers.

  6. Modeling the Nuclear Fuel Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Jacob J. Jacobson; A. M. Yacout; G. E. Matthern; S. J. Piet; A. Moisseytsev

    2005-07-01

    The Advanced Fuel Cycle Initiative is developing a system dynamics model as part of their broad systems analysis of future nuclear energy in the United States. The model will be used to analyze and compare various proposed technology deployment scenarios. The model will also give a better understanding of the linkages between the various components of the nuclear fuel cycle that includes uranium resources, reactor number and mix, nuclear fuel type and waste management. Each of these components is tightly connected to the nuclear fuel cycle but usually analyzed in isolation of the other parts. This model will attempt to bridge these components into a single model for analysis. This work is part of a multi-national laboratory effort between Argonne National Laboratory, Idaho National Laboratory and United States Department of Energy. This paper summarizes the basics of the system dynamics model and looks at some results from the model.

  7. FUEL3-D: A Spatially Explicit Fractal Fuel Distribution Model

    Science.gov (United States)

    Russell A. Parsons

    2006-01-01

    Efforts to quantitatively evaluate the effectiveness of fuels treatments are hampered by inconsistencies between the spatial scale at which fuel treatments are implemented and the spatial scale, and detail, with which we model fire and fuel interactions. Central to this scale inconsistency is the resolution at which variability within the fuel bed is considered. Crown...

  8. Temperature influences in receiver clock modelling

    Science.gov (United States)

    Wang, Kan; Meindl, Michael; Rothacher, Markus; Schoenemann, Erik; Enderle, Werner

    2016-04-01

    In Precise Point Positioning (PPP), hardware delays at the receiver site (receiver, cables, antenna, …) are always difficult to be separated from the estimated receiver clock parameters. As a result, they are partially or fully contained in the estimated "apparent" clocks and will influence the deterministic and stochastic modelling of the receiver clock behaviour. In this contribution, using three years of data, the receiver clock corrections of a set of high-precision Hydrogen Masers (H-Masers) connected to stations of the ESA/ESOC network and the International GNSS Service (IGS) are firstly characterized concerning clock offsets, drifts, modified Allan deviations and stochastic parameters. In a second step, the apparent behaviour of the clocks is modelled with the help of a low-order polynomial and a known temperature coefficient (Weinbach, 2013). The correlations between the temperature and the hardware delays generated by different types of antennae are then analysed looking at daily, 3-day and weekly time intervals. The outcome of these analyses is crucial, if we intend to model the receiver clocks in the ground station network to improve the estimation of station-related parameters like coordinates, troposphere zenith delays and ambiguities. References: Weinbach, U. (2013) Feasibility and impact of receiver clock modeling in precise GPS data analysis. Dissertation, Leibniz Universität Hannover, Germany.

  9. Quadratic reactivity fuel cycle model

    Energy Technology Data Exchange (ETDEWEB)

    Lewins, J.D.

    1985-11-01

    For educational purposes it is highly desirable to provide simple yet realistic models for fuel cycle and fuel economy. In particular, a lumped model without recourse to detailed spatial calculations would be very helpful in providing the student with a proper understanding of the purposes of fuel cycle calculations. A teaching model for fuel cycle studies based on a lumped model assuming the summability of partial reactivities with a linear dependence of reactivity usefully illustrates fuel utilization concepts. The linear burnup model does not satisfactorily represent natural enrichment reactors. A better model, showing the trend of initial plutonium production before subsequent fuel burnup and fission product generation, is a quadratic fit. The study of M-batch cycles, reloading 1/Mth of the core at end of cycle, is now complicated by nonlinear equations. A complete account of the asymptotic cycle for any order of M-batch refueling can be given and compared with the linear model. A complete account of the transient cycle can be obtained readily in the two-batch model and this exact solution would be useful in verifying numerical marching models. It is convenient to treat the parabolic fit rho = 1 - tau/sup 2/ as a special case of the general quadratic fit rho = 1 - C/sub tau/ - (1 - C)tau/sup 2/ in suitably normalized reactivity and cycle time units. The parabolic results are given in this paper.

  10. PEM Fuel Cells - Fundamentals, Modeling and Applications

    Directory of Open Access Journals (Sweden)

    Maher A.R. Sadiq Al-Baghdadi

    2013-01-01

    Full Text Available Part I: Fundamentals Chapter 1: Introduction. Chapter 2: PEM fuel cell thermodynamics, electrochemistry, and performance. Chapter 3: PEM fuel cell components. Chapter 4: PEM fuel cell failure modes. Part II: Modeling and Simulation Chapter 5: PEM fuel cell models based on semi-empirical simulation. Chapter 6: PEM fuel cell models based on computational fluid dynamics. Part III: Applications Chapter 7: PEM fuel cell system design and applications.

  11. Receiving Basin for Offsite Fuels and the Resin Regeneration Facility Safety Analysis Report, Executive Summary

    Energy Technology Data Exchange (ETDEWEB)

    Shedrow, C.B.

    1999-11-29

    The Safety Analysis Report documents the safety authorization basis for the Receiving Basin for Offsite Fuels (RBOF) and the Resin Regeneration Facility (RRF) at the Savannah River Site (SRS). The present mission of the RBOF and RRF is to continue in providing a facility for the safe receipt, storage, handling, and shipping of spent nuclear fuel assemblies from power and research reactors in the United States, fuel from SRS and other Department of Energy (DOE) reactors, and foreign research reactors fuel, in support of the nonproliferation policy. The RBOF and RRF provide the capability to handle, separate, and transfer wastes generated from nuclear fuel element storage. The DOE and Westinghouse Savannah River Company, the prime operating contractor, are committed to managing these activities in such a manner that the health and safety of the offsite general public, the site worker, the facility worker, and the environment are protected.

  12. Alternative fuels and vehicles choice model

    Energy Technology Data Exchange (ETDEWEB)

    Greene, D.L. [Oak Ridge National Lab., TN (United States). Center for Transportation Analysis

    1994-10-01

    This report describes the theory and implementation of a model of alternative fuel and vehicle choice (AFVC), designed for use with the US Department of Energy`s Alternative Fuels Trade Model (AFTM). The AFTM is a static equilibrium model of the world supply and demand for liquid fuels, encompassing resource production, conversion processes, transportation, and consumption. The AFTM also includes fuel-switching behavior by incorporating multinomial logit-type equations for choice of alternative fuel vehicles and alternative fuels. This allows the model to solve for market shares of vehicles and fuels, as well as for fuel prices and quantities. The AFVC model includes fuel-flexible, bi-fuel, and dedicated fuel vehicles. For multi-fuel vehicles, the choice of fuel is subsumed within the vehicle choice framework, resulting in a nested multinomial logit design. The nesting is shown to be required by the different price elasticities of fuel and vehicle choice. A unique feature of the AFVC is that its parameters are derived directly from the characteristics of alternative fuels and vehicle technologies, together with a few key assumptions about consumer behavior. This not only establishes a direct link between assumptions and model predictions, but facilitates sensitivity testing, as well. The implementation of the AFVC model as a spreadsheet is also described.

  13. Numerical modelling of fuel sprays

    Energy Technology Data Exchange (ETDEWEB)

    Bergstroem, C.

    1999-06-01

    The way the fuel is introduced into the combustion chamber is one of the most important parameters for the power output and the generation of emissions in the combustion of liquid fuels. The interaction between the turbulent gas flow field and the liquid fuel droplets, the vaporisation of them and the mixing of the gaseous fuel with the ambient air that are vital parameters in the combustion process. The use of numerical calculations is an important tool to better understand these complex interacting phenomena. This thesis reports on the numerical modelling of fuel sprays in non-reacting cases using an own developed spray module. The spray module uses the stochastic parcel method to represent the spray. The module was made in such manner that it could by coupled with different gas flow solver. Results obtained from four different gas flow solvers are presented in the thesis, including the use of two different kinds of turbulence models. In the first part the spray module is coupled with a k-{eta} based 2-D cylindrical gas flow solver. A thorough sensitivity analysis was performed on the spray and gas flow solver parameters, such as grid size dependence and sensitivity to initial values of k-{eta}. The results of the spray module were also compared to results from other spray codes, e.g. the well known KIVA code. In the second part of this thesis the spray was injected into a turbulent and fully developed crossflow studied. The spray module was attached to a LES (Large Eddy Simulation) based flow solvers enabling the study of the complex structures and time dependent phenomena involved in spray in crossflows. It was found that the spray performs an oscillatory motion and that the Strouhal number in the wake was about 0.1. Different spray breakup models were evaluated by comparing with experimental results 66 refs, 56 figs

  14. Chemical Kinetic Modeling of Advanced Transportation Fuels

    Energy Technology Data Exchange (ETDEWEB)

    PItz, W J; Westbrook, C K; Herbinet, O

    2009-01-20

    Development of detailed chemical kinetic models for advanced petroleum-based and nonpetroleum based fuels is a difficult challenge because of the hundreds to thousands of different components in these fuels and because some of these fuels contain components that have not been considered in the past. It is important to develop detailed chemical kinetic models for these fuels since the models can be put into engine simulation codes used for optimizing engine design for maximum efficiency and minimal pollutant emissions. For example, these chemistry-enabled engine codes can be used to optimize combustion chamber shape and fuel injection timing. They also allow insight into how the composition of advanced petroleum-based and non-petroleum based fuels affect engine performance characteristics. Additionally, chemical kinetic models can be used separately to interpret important in-cylinder experimental data and gain insight into advanced engine combustion processes such as HCCI and lean burn engines. The objectives are: (1) Develop detailed chemical kinetic reaction models for components of advanced petroleum-based and non-petroleum based fuels. These fuels models include components from vegetable-oil-derived biodiesel, oil-sand derived fuel, alcohol fuels and other advanced bio-based and alternative fuels. (2) Develop detailed chemical kinetic reaction models for mixtures of non-petroleum and petroleum-based components to represent real fuels and lead to efficient reduced combustion models needed for engine modeling codes. (3) Characterize the role of fuel composition on efficiency and pollutant emissions from practical automotive engines.

  15. VISION: Verifiable Fuel Cycle Simulation Model

    Energy Technology Data Exchange (ETDEWEB)

    Jacob J. Jacobson; Abdellatif M. Yacout; Gretchen E. Matthern; Steven J. Piet; David E. Shropshire

    2009-04-01

    The nuclear fuel cycle is a very complex system that includes considerable dynamic complexity as well as detail complexity. In the nuclear power realm, there are experts and considerable research and development in nuclear fuel development, separations technology, reactor physics and waste management. What is lacking is an overall understanding of the entire nuclear fuel cycle and how the deployment of new fuel cycle technologies affects the overall performance of the fuel cycle. The Advanced Fuel Cycle Initiative’s systems analysis group is developing a dynamic simulation model, VISION, to capture the relationships, timing and delays in and among the fuel cycle components to help develop an understanding of how the overall fuel cycle works and can transition as technologies are changed. This paper is an overview of the philosophy and development strategy behind VISION. The paper includes some descriptions of the model and some examples of how to use VISION.

  16. Model Year 2017 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-11-01

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles.

  17. Model Year 2011 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2010-11-01

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles.

  18. Model Year 2012 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2011-11-01

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles.

  19. Model Year 2013 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2012-12-01

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles.

  20. Modeling and Simulation of Nuclear Fuel Materials

    Energy Technology Data Exchange (ETDEWEB)

    Devanathan, Ramaswami; Van Brutzel, Laurent; Chartier, Alan; Gueneau, Christine; Mattsson, Ann E.; Tikare, Veena; Bartel, Timothy; Besmann, T. M.; Stan, Marius; Van Uffelen, Paul

    2010-10-01

    We review the state of modeling and simulation of nuclear fuels with emphasis on the most widely used nuclear fuel, UO2. The hierarchical scheme presented represents a science-based approach to modeling nuclear fuels by progressively passing information in several stages from ab initio to continuum levels. Such an approach is essential to overcome the challenges posed by radioactive materials handling, experimental limitations in modeling extreme conditions and accident scenarios, and the small time and distance scales of fundamental defect processes. When used in conjunction with experimental validation, this multiscale modeling scheme can provide valuable guidance to development of fuel for advanced reactors to meet rising global energy demand.

  1. Progress on Fuel Receiving and Storage Decontamination Work at the West Valley Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    Jablonski, J. F.; Al-Daouk, A. M.; Moore, H. R.

    2003-02-25

    The West Valley Demonstration Project (WVDP) removed the last of its spent nuclear fuel assemblies from an on-site storage pool last year and is now decontaminating its Fuel Receiving and Storage (FRS) Facility. The decontamination project will reduce the long-lived curie inventory, associated radiological hazards, and the operational costs associated with the maintenance of this facility. Workers at the WVDP conducted the first phase of the FRS decontamination project in late 2001 by removing 149 canisters that previously contained spent fuel assemblies from the pool. Removal of the canisters from the pool paved the way for nuclear divers to begin removing canister storage racks and other miscellaneous material from the FRS pool in February 2002. This was only the third time in the history of the WVDP that nuclear divers were used to perform underwater work. After decontaminating the pool, it will be drained slowly until all of the water is removed. The water will be processed through an ion exchanger to remove radioactive contaminants as it is being drained, and a fixative will be applied to the walls above the water surface to secure residual contamination.

  2. Used Fuel Testing Transportation Model

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Steven B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Best, Ralph E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Maheras, Steven J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jensen, Philip J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); England, Jeffery L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); LeDuc, Dan [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-09-25

    This report identifies shipping packages/casks that might be used by the Used Nuclear Fuel Disposition Campaign Program (UFDC) to ship fuel rods and pieces of fuel rods taken from high-burnup used nuclear fuel (UNF) assemblies to and between research facilities for purposes of evaluation and testing. Also identified are the actions that would need to be taken, if any, to obtain U.S. Nuclear Regulatory (NRC) or other regulatory authority approval to use each of the packages and/or shipping casks for this purpose.

  3. Used Fuel Testing Transportation Model

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Steven B.; Best, Ralph E.; Maheras, Steven J.; Jensen, Philip J.; England, Jeffery L.; LeDuc, Dan

    2014-09-24

    This report identifies shipping packages/casks that might be used by the Used Nuclear Fuel Disposition Campaign Program (UFDC) to ship fuel rods and pieces of fuel rods taken from high-burnup used nuclear fuel (UNF) assemblies to and between research facilities for purposes of evaluation and testing. Also identified are the actions that would need to be taken, if any, to obtain U.S. Nuclear Regulatory (NRC) or other regulatory authority approval to use each of the packages and/or shipping casks for this purpose.

  4. Aids to determining fuel models for estimating fire behavior

    Science.gov (United States)

    Hal E. Anderson

    1982-01-01

    Presents photographs of wildland vegetation appropriate for the 13 fuel models used in mathematical models of fire behavior. Fuel model descriptions include fire behavior associated with each fuel and its physical characteristics. A similarity chart cross-references the 13 fire behavior fuel models to the 20 fuel models used in the National Fire Danger Rating System....

  5. Active Versus Passive: Receiver Model Transforms for Diffusive Molecular Communication

    CERN Document Server

    Noel, Adam; Makrakis, Dimitrios; Hafid, Abdelhakim

    2016-01-01

    This paper presents an analytical comparison of the active and passive receiver models in diffusive molecular communication. In the active model, molecules are absorbed when they collide with the receiver surface. In the passive model, the receiver is a virtual boundary that does not affect molecule behavior. Two approaches are presented to derive transforms between the active and passive receiver signals. As an example, we unify the two models for an unbounded diffusion-only molecular communication system with a spherical receiver. As time increases in the three-dimensional system, the transform functions have constant scaling factors, such that the receiver models are effectively equivalent. Methods are presented to enable the transformation of stochastic simulations, which are used to verify the transforms and demonstrate that transforming the simulation of a passive receiver can be more efficient and more accurate than the direct simulation of an absorbing receiver.

  6. Model Year 2016 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2015-11-01

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles. The vehicles listed have been divided into three classes of cars, three classes of light duty trucks, and three classes of special purpose vehicles.

  7. Model Year 2005 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2004-11-01

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles. The vehicles listed have been divided into three classes of cars, three classes of light duty trucks, and three classes of special purpose vehicles.

  8. Model Year 2008 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2007-10-01

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles. The vehicles listed have been divided into three classes of cars, three classes of light duty trucks, and three classes of special purpose vehicles.

  9. Model Year 2009 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2008-10-01

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles. The vehicles listed have been divided into three classes of cars, three classes of light duty trucks, and three classes of special purpose vehicles.

  10. Model Year 2007 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2007-10-01

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles. The vehicles listed have been divided into three classes of cars, three classes of light duty trucks, and three classes of special purpose vehicles.

  11. Model Year 2006 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2005-11-01

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles. The vehicles listed have been divided into three classes of cars, three classes of light duty trucks, and three classes of special purpose vehicles.

  12. Model Year 2015 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2014-12-01

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles. The vehicles listed have been divided into three classes of cars, three classes of light duty trucks, and three classes of special purpose vehicles.

  13. Model Year 2010 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-10-14

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles. The vehicles listed have been divided into three classes of cars, three classes of light duty trucks, and three classes of special purpose vehicles.

  14. Model Year 2014 Fuel Economy Guide: EPA Fuel Economy Estimates

    Energy Technology Data Exchange (ETDEWEB)

    None

    2013-12-01

    The Fuel Economy Guide is published by the U.S. Department of Energy as an aid to consumers considering the purchase of a new vehicle. The Guide lists estimates of miles per gallon (mpg) for each vehicle available for the new model year. These estimates are provided by the U.S. Environmental Protection Agency in compliance with Federal Law. By using this Guide, consumers can estimate the average yearly fuel cost for any vehicle. The Guide is intended to help consumers compare the fuel economy of similarly sized cars, light duty trucks and special purpose vehicles. The vehicles listed have been divided into three classes of cars, three classes of light duty trucks, and three classes of special purpose vehicles.

  15. Modeling of hybrid vehicle fuel economy and fuel engine efficiency

    Science.gov (United States)

    Wu, Wei

    "Near-CV" (i.e., near-conventional vehicle) hybrid vehicles, with an internal combustion engine, and a supplementary storage with low-weight, low-energy but high-power capacity, are analyzed. This design avoids the shortcoming of the "near-EV" and the "dual-mode" hybrid vehicles that need a large energy storage system (in terms of energy capacity and weight). The small storage is used to optimize engine energy management and can provide power when needed. The energy advantage of the "near-CV" design is to reduce reliance on the engine at low power, to enable regenerative braking, and to provide good performance with a small engine. The fuel consumption of internal combustion engines, which might be applied to hybrid vehicles, is analyzed by building simple analytical models that reflect the engines' energy loss characteristics. Both diesel and gasoline engines are modeled. The simple analytical models describe engine fuel consumption at any speed and load point by describing the engine's indicated efficiency and friction. The engine's indicated efficiency and heat loss are described in terms of several easy-to-obtain engine parameters, e.g., compression ratio, displacement, bore and stroke. Engine friction is described in terms of parameters obtained by fitting available fuel measurements on several diesel and spark-ignition engines. The engine models developed are shown to conform closely to experimental fuel consumption and motored friction data. A model of the energy use of "near-CV" hybrid vehicles with different storage mechanism is created, based on simple algebraic description of the components. With powertrain downsizing and hybridization, a "near-CV" hybrid vehicle can obtain a factor of approximately two in overall fuel efficiency (mpg) improvement, without considering reductions in the vehicle load.

  16. Modeling Fuel Efficiency: MPG or GPHM?

    Science.gov (United States)

    Bartkovich, Kevin G.

    2013-01-01

    The standard for measuring fuel efficiency in the U.S. has been miles per gallon (mpg). However, the Environmental Protection Agency's (EPA) switch in rating fuel efficiency from miles per gallon to gallons per hundred miles with the 2013 model-year cars leads to interesting and relevant mathematics with real-world connections. By modeling…

  17. Transmutation Fuel Performance Code Thermal Model Verification

    Energy Technology Data Exchange (ETDEWEB)

    Gregory K. Miller; Pavel G. Medvedev

    2007-09-01

    FRAPCON fuel performance code is being modified to be able to model performance of the nuclear fuels of interest to the Global Nuclear Energy Partnership (GNEP). The present report documents the effort for verification of the FRAPCON thermal model. It was found that, with minor modifications, FRAPCON thermal model temperature calculation agrees with that of the commercial software ABAQUS (Version 6.4-4). This report outlines the methodology of the verification, code input, and calculation results.

  18. Fuel Conditioning Facility Electrorefiner Process Model

    Energy Technology Data Exchange (ETDEWEB)

    DeeEarl Vaden

    2005-10-01

    The Fuel Conditioning Facility at the Idaho National Laboratory processes spent nuclear fuel from the Experimental Breeder Reactor II using electro-metallurgical treatment. To process fuel without waiting for periodic sample analyses to assess process conditions, an electrorefiner process model predicts the composition of the electrorefiner inventory and effluent streams. For the chemical equilibrium portion of the model, the two common methods for solving chemical equilibrium problems, stoichiometric and non stoichiometric, were investigated. In conclusion, the stoichiometric method produced equilibrium compositions close to the measured results whereas the non stoichiometric method did not.

  19. Standard fire behavior fuel models: a comprehensive set for use with Rothermel's surface fire spread model

    Science.gov (United States)

    Joe H. Scott; Robert E. Burgan

    2005-01-01

    This report describes a new set of standard fire behavior fuel models for use with Rothermel's surface fire spread model and the relationship of the new set to the original set of 13 fire behavior fuel models. To assist with transition to using the new fuel models, a fuel model selection guide, fuel model crosswalk, and set of fuel model photos are provided.

  20. Modeling and control of fuel cell systems and fuel processors

    Science.gov (United States)

    Pukrushpan, Jay Tawee

    Fuel cell systems offer clean and efficient energy production and are currently under intensive development by several manufacturers for both stationary and mobile applications. The viability, efficiency, and robustness of this technology depend on understanding, predicting, and controlling the unique transient behavior of the fuel cell system. In this thesis, we employ phenomenological modeling and multivariable control techniques to provide fast and consistent system dynamic behavior. Moreover, a framework for analyzing and evaluating different control architectures and sensor sets is provided. Two fuel cell related control problems are investigated in this study, namely, the control of the cathode oxygen supply for a high-pressure direct hydrogen Fuel Cell System (FCS) and control of the anode hydrogen supply from a natural gas Fuel Processor System (FPS). System dynamic analysis and control design is carried out using model-based linear control approaches. A system level dynamic model suitable for each control problem is developed from physics-based component models. The transient behavior captured in the model includes flow characteristics, inertia dynamics, lumped-volume manifold filling dynamics, time evolving spatially-homogeneous reactant pressure or mole fraction, membrane humidity, and the Catalytic Partial Oxidation (CPOX) reactor temperature. The goal of the FCS control problem is to effectively regulate the oxygen concentration in the cathode by quickly and accurately replenishing oxygen depleted during power generation. The features and limitations of different control configurations and the effect of various measurement on the control performance are examined. For example, an observability analysis suggests using the stack voltage measurement as feedback to the observer-based controller to improve the closed loop performance. The objective of the FPS control system is to regulate both the CPOX temperature and anode hydrogen concentration. Linear

  1. MARMOT update for oxide fuel modeling

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yongfeng [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schwen, Daniel [Idaho National Lab. (INL), Idaho Falls, ID (United States); Chakraborty, Pritam [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jiang, Chao [Idaho National Lab. (INL), Idaho Falls, ID (United States); Aagesen, Larry [Idaho National Lab. (INL), Idaho Falls, ID (United States); Ahmed, Karim [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jiang, Wen [Idaho National Lab. (INL), Idaho Falls, ID (United States); Biner, Bulent [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bai, Xianming [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Tonks, Michael [Pennsylvania State Univ., University Park, PA (United States); Millett, Paul [Univ. of Arkansas, Fayetteville, AR (United States)

    2016-09-01

    This report summarizes the lower-length-scale research and development progresses in FY16 at Idaho National Laboratory in developing mechanistic materials models for oxide fuels, in parallel to the development of the MARMOT code which will be summarized in a separate report. This effort is a critical component of the microstructure based fuel performance modeling approach, supported by the Fuels Product Line in the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program. The progresses can be classified into three categories: 1) development of materials models to be used in engineering scale fuel performance modeling regarding the effect of lattice defects on thermal conductivity, 2) development of modeling capabilities for mesoscale fuel behaviors including stage-3 gas release, grain growth, high burn-up structure, fracture and creep, and 3) improved understanding in material science by calculating the anisotropic grain boundary energies in UO$_2$ and obtaining thermodynamic data for solid fission products. Many of these topics are still under active development. They are updated in the report with proper amount of details. For some topics, separate reports are generated in parallel and so stated in the text. The accomplishments have led to better understanding of fuel behaviors and enhance capability of the MOOSE-BISON-MARMOT toolkit.

  2. Fossil fuels supplies modeling and research

    Energy Technology Data Exchange (ETDEWEB)

    Leiby, P.N.

    1996-06-01

    The fossil fuel supplies modeling and research effort focuses on models for US Strategic Petroleum Reserve (SPR) planning and management. Topics covered included new SPR oil valuation models, updating models for SPR risk analysis, and fill-draw planning. Another task in this program area is the development of advanced computational tools for three-dimensional seismic analysis.

  3. Mathematical modeling of biomass fuels formation process.

    Science.gov (United States)

    Gaska, Krzysztof; Wandrasz, Andrzej J

    2008-01-01

    The increasing demand for thermal and electric energy in many branches of industry and municipal management accounts for a drastic diminishing of natural resources (fossil fuels). Meanwhile, in numerous technical processes, a huge mass of wastes is produced. A segregated and converted combustible fraction of the wastes, with relatively high calorific value, may be used as a component of formed fuels. The utilization of the formed fuel components from segregated groups of waste in associated processes of co-combustion with conventional fuels causes significant savings resulting from partial replacement of fossil fuels, and reduction of environmental pollution resulting directly from the limitation of waste migration to the environment (soil, atmospheric air, surface and underground water). The realization of technological processes with the utilization of formed fuel in associated thermal systems should be qualified by technical criteria, which means that elementary processes as well as factors of sustainable development, from a global viewpoint, must not be disturbed. The utilization of post-process waste should be preceded by detailed technical, ecological and economic analyses. In order to optimize the mixing process of fuel components, a mathematical model of the forming process was created. The model is defined as a group of data structures which uniquely identify a real process and conversion of this data in algorithms based on a problem of linear programming. The paper also presents the optimization of parameters in the process of forming fuels using a modified simplex algorithm with a polynomial worktime. This model is a datum-point in the numerical modeling of real processes, allowing a precise determination of the optimal elementary composition of formed fuels components, with assumed constraints and decision variables of the task.

  4. The Sender-Receiver Model and the Targeting Process.

    Science.gov (United States)

    Larson, Mark A.

    The goal of this paper is to describe how one classroom teacher uses the Sender-Receiver Communications Model to illustrate for students in a lively and memorable way the process of "targeting your audience" with medium and message. Students are used as examples of Receivers, or target audience, illustrating the potential range of…

  5. Comparison of Different Fuel Temperature Models

    Energy Technology Data Exchange (ETDEWEB)

    Weddig, Beatrice

    2003-02-01

    The purpose of this work is to improve the performance of the core calculation system used in Ringhals for in-core fuel management. It has been observed that, whereas the codes yield results that are in good agreement with measurements when the core operates at full nominal power, this agreement deteriorates noticeably when the reactor is running at reduced power. This deficiency of the code system was observed by comparing the calculated and measured boron concentrations in the moderator of the PWR. From the neutronic point of view, the difference between full power and reduced power in the same core is the different temperature of the fuel and the moderator. Whereas the coolant temperature can be measured and is thus relatively well known, the fuel temperature is only inferred from the moderator temperature as well as neutron physics and heat transfer calculations. The most likely reason for the above mentioned discrepancy is therefore the uncertainty of the fuel temperature at low power, and hence the incorrect calculation of the fuel temperature reactivity feedback through the so called Doppler effect. To obtain the fuel temperature at low power, usually some semi-empirical relations, sometimes called correlations, are used. The above-mentioned inaccuracy of the core calculation procedures can thus be tracked down to the insufficiency of these correlations. Therefore, the suggestion is that the above mentioned deficiency of the core calculation codes can be eliminated or reduced if the fuel temperature correlations are improved. An improved model, called the 30% model, is implemented in SIMULATE-3, the core calculation code used at Ringhals. The accuracy of the 30% model was compared to that of the present model by considering a number of cases, where measured values of the boron concentration at low power were available, and comparing them with calculated values using both the present and the new model. It was found that on the whole, the new fuel temperature

  6. Modeling Deep Burn TRISO particle nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Besmann, T.M., E-mail: besmanntm@ornl.gov [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Stoller, R.E., E-mail: stollerre@ornl.gov [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Samolyuk, G., E-mail: samolyukgd@ornl.gov [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Schuck, P.C., E-mail: schuckpc@ornl.gov [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Golubov, S.I., E-mail: golubovsi@ornl.gov [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Rudin, S.P., E-mail: srudin@lanl.gov [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Wills, J.M., E-mail: jxw@lanl.gov [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Coe, J.D., E-mail: jcoe@lanl.gov [Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545 (United States); Wirth, B.D., E-mail: bdwirth@utk.edu [University of Tennessee, Knoxville, TN 37996-0750 (United States); Kim, S., E-mail: sungtae@cae.wisc.edu [University of Wisconsin, 1509 University Ave., Madison, WI 53706 (United States); Morgan, D.D., E-mail: ddmorgan@engr.wisc.edu [University of Wisconsin, 1509 University Ave., Madison, WI 53706 (United States); Szlufarska, I., E-mail: izabela@engr.wisc.edu [University of Wisconsin, 1509 University Ave., Madison, WI 53706 (United States)

    2012-11-15

    Under the DOE Deep Burn program TRISO fuel is being investigated as a fuel form for consuming plutonium and minor actinides, and for greater efficiency in uranium utilization. The result will thus be to drive TRISO particulate fuel to very high burn-ups. In the current effort the various phenomena in the TRISO particle are being modeled using a variety of techniques. The chemical behavior is being treated utilizing thermochemical analysis to identify phase formation/transformation and chemical activities in the particle, including kernel migration. Density functional theory is being used to understand fission product diffusion within the plutonia oxide kernel, the fission product's attack on the SiC coating layer, as well as fission product diffusion through an alternative coating layer, ZrC. Finally, a multiscale approach is being used to understand thermal transport, including the effect of radiation damage induced defects, in a model SiC material.

  7. Thermal Model of a Dish Stirling Cavity-Receiver

    OpenAIRE

    Rubén Gil; Carlos Monné; Nuria Bernal; Mariano Muñoz; Francisco Moreno

    2015-01-01

    This paper presents a thermal model for a dish Stirling cavity based on the finite differences method. This model is a theoretical tool to optimize the cavity in terms of thermal efficiency. One of the main outcomes of this work is the evaluation of radiative exchange using the radiosity method; for that purpose, the view factors of all surfaces involved have been accurately calculated. Moreover, this model enables the variation of the cavity and receiver dimensions and the materials to deter...

  8. Fuel consumption models for pine flatwoods fuel types in the southeastern United States

    Science.gov (United States)

    Clinton S. Wright

    2013-01-01

    Modeling fire effects, including terrestrial and atmospheric carbon fluxes and pollutant emissions during wildland fires, requires accurate predictions of fuel consumption. Empirical models were developed for predicting fuel consumption from fuel and environmental measurements on a series of operational prescribed fires in pine flatwoods ecosystems in the southeastern...

  9. BEHAVE: fire behavior prediction and fuel modeling system--FUEL subsystem

    Science.gov (United States)

    Robert E. Burgan; Richard C. Rothermel

    1984-01-01

    This manual documents the fuel modeling procedures of BEHAVE--a state-of-the-art wildland fire behavior prediction system. Described are procedures for collecting fuel data, using the data with the program, and testing and adjusting the fuel model.

  10. MMSNF 2005. Materials models and simulations for nuclear fuels

    Energy Technology Data Exchange (ETDEWEB)

    Freyss, M.; Durinck, J.; Carlot, G.; Sabathier, C.; Martin, P.; Garcia, P.; Ripert, M.; Blanpain, P.; Lippens, M.; Schut, H.; Federov, A.V.; Bakker, K.; Osaka, M.; Miwa, S.; Sato, I.; Tanaka, K.; Kurosaki, K.; Uno, M.; Yamanaka, S.; Govers, K.; Verwerft, M.; Hou, M.; Lemehov, S.E.; Terentyev, D.; Govers, K.; Kotomin, E.A.; Ashley, N.J.; Grimes, R.W.; Van Uffelen, P.; Mastrikov, Y.; Zhukovskii, Y.; Rondinella, V.V.; Kurosaki, K.; Uno, M.; Yamanaka, S.; Minato, K.; Phillpot, S.; Watanabe, T.; Shukla, P.; Sinnott, S.; Nino, J.; Grimes, R.; Staicu, D.; Hiernaut, J.P.; Wiss, T.; Rondinella, V.V.; Ronchi, C.; Yakub, E.; Kaye, M.H.; Morrison, C.; Higgs, J.D.; Akbari, F.; Lewis, B.J.; Thompson, W.T.; Gueneau, C.; Gosse, S.; Chatain, S.; Dumas, J.C.; Sundman, B.; Dupin, N.; Konings, R.; Noel, H.; Veshchunov, M.; Dubourg, R.; Ozrin, C.V.; Veshchunov, M.S.; Welland, M.T.; Blanc, V.; Michel, B.; Ricaud, J.M.; Calabrese, R.; Vettraino, F.; Tverberg, T.; Kissane, M.; Tulenko, J.; Stan, M.; Ramirez, J.C.; Cristea, P.; Rachid, J.; Kotomin, E.; Ciriello, A.; Rondinella, V.V.; Staicu, D.; Wiss, T.; Konings, R.; Somers, J.; Killeen, J

    2006-07-01

    The MMSNF Workshop series aims at stimulating research and discussions on models and simulations of nuclear fuels and coupling the results into fuel performance codes.This edition was focused on materials science and engineering for fuel performance codes. The presentations were grouped in three technical sessions: fundamental modelling of fuel properties; integral fuel performance codes and their validation; collaborations and integration of activities. (A.L.B.)

  11. Modeling of Proton-Conducting Solid Oxide Fuel Cells Fueled with Syngas

    OpenAIRE

    2014-01-01

    Solid oxide fuel cells (SOFCs) with proton conducting electrolyte (H-SOFCs) are promising power sources for stationary applications. Compared with other types of fuel cells, one distinct feature of SOFC is their fuel flexibility. In this study, a 2D model is developed to investigate the transport and reaction in an H-SOFC fueled with syngas, which can be produced from conventional natural gas or renewable biomass. The model fully considers the fluid flow, mass transfer, heat transfer and r...

  12. Gaussian mixture models as flux prediction method for central receivers

    Science.gov (United States)

    Grobler, Annemarie; Gauché, Paul; Smit, Willie

    2016-05-01

    Flux prediction methods are crucial to the design and operation of central receiver systems. Current methods such as the circular and elliptical (bivariate) Gaussian prediction methods are often used in field layout design and aiming strategies. For experimental or small central receiver systems, the flux profile of a single heliostat often deviates significantly from the circular and elliptical Gaussian models. Therefore a novel method of flux prediction was developed by incorporating the fitting of Gaussian mixture models onto flux profiles produced by flux measurement or ray tracing. A method was also developed to predict the Gaussian mixture model parameters of a single heliostat for a given time using image processing. Recording the predicted parameters in a database ensures that more accurate predictions are made in a shorter time frame.

  13. Thermal Model of a Dish Stirling Cavity-Receiver

    Directory of Open Access Journals (Sweden)

    Rubén Gil

    2015-01-01

    Full Text Available This paper presents a thermal model for a dish Stirling cavity based on the finite differences method. This model is a theoretical tool to optimize the cavity in terms of thermal efficiency. One of the main outcomes of this work is the evaluation of radiative exchange using the radiosity method; for that purpose, the view factors of all surfaces involved have been accurately calculated. Moreover, this model enables the variation of the cavity and receiver dimensions and the materials to determine the optimal cavity design. The tool has been used to study the cavity optimization regarding geometry parameters and material properties. Receiver absorptivity has been identified as the most influential property of the materials. The optimal aperture height depends on the minimum focal space.

  14. A comparative study of approaches to direct methanol fuel cells modelling

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, V.B.; Falcao, D.S.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Eng. Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Rangel, C.M. [Instituto Nacional de Engenharia, Tecnologia e Inovacao, Paco do Lumiar, 22,1649-038 (Portugal)

    2007-03-15

    Fuel cell modelling has received much attention over the past decade in an attempt to better understand the phenomena occurring within the cell. Mathematical models and simulation are needed as tools for design optimization of fuel cells, stacks and fuel cell power systems. Analytical, semi-empirical and mechanistic models for direct methanol fuel cells (DMFC) are reviewed. Effective models were until now developed describing the fundamental electrochemical and transport phenomena taking place in the cell. More research is required to develop models that can account for the two-phase flows occurring in the anode and cathode of the DMFC. The merits and demerits of the models are presented. Selected models of different categories are implemented and discussed. Finally, one of the selected simplified models is proposed as a computer-aided tool for real-time system level DMFC calculations. (author)

  15. FAST: A Fuel And Sheath Modeling Tool for CANDU Reactor Fuel

    Science.gov (United States)

    Prudil, Andrew Albert

    Understanding the behaviour of nuclear fuel during irradiation is a complicated multiphysics problem involving neutronics, chemistry, radiation physics, material-science, solid mechanics, heat transfer and thermal-hydraulics. Due to the complexity and interdependence of the physics and models involved, fuel modeling is typically clone with numerical models. Advancements in both computer hardware and software have made possible new more complex and sophisticated fuel modeling codes. The Fuel And Sheath modelling Tool (FAST) is a fuel performance code that has been developed for modeling nuclear fuel behaviour under normal and transient conditions. The FAST code includes models for heat generation and transport, thermal expansion, elastic strain, densification, fission product swelling, pellet relocation, contact, grain growth, fission gas release, gas and coolant pressure and sheath creep. These models are coupled and solved numerically using the Comsol Multiphysics finite-element platform. The model utilizes a radialaxial geometry of a fuel pellet (including dishing and chamfering) and accompanying fuel sheath allowing the model to predict circumferential ridging. This model has evolved from previous treatments developed at the Royal Military College. The model has now been significantly advanced to include: a more detailed pellet geometry, localized pellet-to-sheath gap size and contact pressure, ability to model cracked pellets, localized fuel burnup for material property models, improved U02 densification behaviour, fully 2-dimensional model for the sheath, additional creep models, additional material models, an FEM Booth-diffusion model for fission gas release (including ability to model temperature and power changes), a capability for end-of-life predictions, the ability to utilize text files as model inputs, and provides a first time integration of normal operating conditions (NOC) and transient fuel models into a single code (which has never been achieved

  16. RECEIVED SIGNAL STRENGTH INDICATION MODELING IN INDOOR WIRELESS SENSOR NETWORKS

    Directory of Open Access Journals (Sweden)

    Edson Taira Procopio

    2013-01-01

    Full Text Available This study aims to identify mathematical models that represent the relation between Received Signal Strength Indication (RSSI and objects in an indoor Wireless Sensor Network (WSN. Using the Least Squares Method, four linear models have been identified: The first one relates uplink RSSI and objects; the second one relates downlink RSSI and objects; the third one relates uplink RSSI and obstacles and the fourth one relates downlink RSSI and obstacles. The obtained results, characterized by small residual values, attest the validation of all four models.

  17. A transient fuel cell model to simulate HTPEM fuel cell impedance spectra

    DEFF Research Database (Denmark)

    Vang, Jakob Rabjerg; Andreasen, Søren Juhl; Kær, Søren Knudsen

    2011-01-01

    This paper presents a spatially resolved transient fuel cell model applied to the simulation of high temperature PEM fuel cell impedance spectra. The model is developed using a 2D finite volume method approach. The model is resolved along the channel and across the membrane. The model considers d...

  18. Fuel model selection for BEHAVE in midwestern oak savannas

    Science.gov (United States)

    Grabner, K.W.; Dwyer, J.P.; Cutter, B.E.

    2001-01-01

    BEHAVE, a fire behavior prediction system, can be a useful tool for managing areas with prescribed fire. However, the proper choice of fuel models can be critical in developing management scenarios. BEHAVE predictions were evaluated using four standardized fuel models that partially described oak savanna fuel conditions: Fuel Model 1 (Short Grass), 2 (Timber and Grass), 3 (Tall Grass), and 9 (Hardwood Litter). Although all four models yielded regressions with R2 in excess of 0.8, Fuel Model 2 produced the most reliable fire behavior predictions.

  19. Modeling Deep Burn TRISO Particle Nuclear Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Besmann, Theodore M [ORNL; Stoller, Roger E [ORNL; Samolyuk, German D [ORNL; Schuck, Paul C [ORNL; Rudin, Sven [Los Alamos National Laboratory (LANL); Wills, John [Los Alamos National Laboratory (LANL); Wirth, Brian D. [University of California, Berkeley; Kim, Sungtae [University of Wisconsin, Madison; Morgan, Dane [University of Wisconsin, Madison; Szlufarska, Izabela [University of Wisconsin, Madison

    2012-01-01

    Under the DOE Deep Burn program TRISO fuel is being investigated as a fuel form for consuming plutonium and minor actinides, and for greater efficiency in uranium utilization. The result will thus be to drive TRISO particulate fuel to very high burn-ups. In the current effort the various phenomena in the TRISO particle are being modeled using a variety of techniques. The chemical behavior is being treated utilizing thermochemical analysis to identify phase formation/transformation and chemical activities in the particle, including kernel migration. First principles calculations are being used to investigate the critical issue of fission product palladium attack on the SiC coating layer. Density functional theory is being used to understand fission product diffusion within the plutonia oxide kernel. Kinetic Monte Carlo techniques are shedding light on transport of fission products, most notably silver, through the carbon and SiC coating layers. The diffusion of fission products through an alternative coating layer, ZrC, is being assessed via DFT methods. Finally, a multiscale approach is being used to understand thermal transport, including the effect of radiation damage induced defects, in a model SiC material.

  20. Boron-10 ABUNCL Models of Fuel Testing

    Energy Technology Data Exchange (ETDEWEB)

    Siciliano, Edward R.; Lintereur, Azaree T.; Kouzes, Richard T.; Ely, James H.

    2013-10-01

    The Department of Energy Office of Nuclear Safeguards and Security (NA-241) is supporting the project Coincidence Counting With Boron-Based Alternative Neutron Detection Technology at Pacific Northwest National Laboratory (PNNL) for the development of a 3He proportional counter alternative neutron coincidence counter. The goal of this project is to design, build and demonstrate a system based upon 10B-lined proportional tubes in a configuration typical for 3He-based coincidence counter applications. This report provides results from MCNP simulations of the General Electric Reuter-Stokes Alternative Boron-Based Uranium Neutron Coincidence Collar (ABUNCL) active configuration model with fuel pins previously measured at Los Alamos National Laboratory. A comparison of the GE-ABUNCL simulations and simulations of 3He based UNCL-II active counter (the system for which the GE-ABUNCL was targeted to replace) with the same fuel pin assemblies is also provided.

  1. Advanced methods of solid oxide fuel cell modeling

    CERN Document Server

    Milewski, Jaroslaw; Santarelli, Massimo; Leone, Pierluigi

    2011-01-01

    Fuel cells are widely regarded as the future of the power and transportation industries. Intensive research in this area now requires new methods of fuel cell operation modeling and cell design. Typical mathematical models are based on the physical process description of fuel cells and require a detailed knowledge of the microscopic properties that govern both chemical and electrochemical reactions. ""Advanced Methods of Solid Oxide Fuel Cell Modeling"" proposes the alternative methodology of generalized artificial neural networks (ANN) solid oxide fuel cell (SOFC) modeling. ""Advanced Methods

  2. A methodology for assessing the market benefits of alternative motor fuels: The Alternative Fuels Trade Model

    Energy Technology Data Exchange (ETDEWEB)

    Leiby, P.N.

    1993-09-01

    This report describes a modeling methodology for examining the prospective economic benefits of displacing motor gasoline use by alternative fuels. The approach is based on the Alternative Fuels Trade Model (AFTM). AFTM development was undertaken by the US Department of Energy (DOE) as part of a longer term study of alternative fuels issues. The AFTM is intended to assist with evaluating how alternative fuels may be promoted effectively, and what the consequences of substantial alternative fuels use might be. Such an evaluation of policies and consequences of an alternative fuels program is being undertaken by DOE as required by Section 502(b) of the Energy Policy Act of 1992. Interest in alternative fuels is based on the prospective economic, environmental and energy security benefits from the substitution of these fuels for conventional transportation fuels. The transportation sector is heavily dependent on oil. Increased oil use implies increased petroleum imports, with much of the increase coming from OPEC countries. Conversely, displacement of gasoline has the potential to reduce US petroleum imports, thereby reducing reliance on OPEC oil and possibly weakening OPEC`s ability to extract monopoly profits. The magnitude of US petroleum import reduction, the attendant fuel price changes, and the resulting US benefits, depend upon the nature of oil-gas substitution and the supply and demand behavior of other world regions. The methodology applies an integrated model of fuel market interactions to characterize these effects.

  3. Process modeling of fuel cell vehicle power system

    Institute of Scientific and Technical Information of China (English)

    CHEN LiMing; LIN ZhaoJia; MA ZiFeng

    2009-01-01

    Constructed here is a mathematic model of PEM Fuel Cell Vehicle Power System which is composed of fuel supply model, fuel cell stack model and water-heat management model. The model was developed by Matiab/Simulink to evaluate how the major operating variables affect the output performances. Itshows that the constructed model can represent characteristics of the power system closely by comparing modeling results with experimental data, and it can be used in the study and design of fuel cell vehicle power system.

  4. Modeling Strategic Interactions to Car and Fuel Taxation

    NARCIS (Netherlands)

    Heijnen, P.; Kooreman, P.

    2006-01-01

    We develop a model to analyse the interactions between actors involved in car and fuel taxation: consumers, car producers, fuel producers and the government. Heterogeneous consumers choose between two versions of a car that differ in engine type (diesel or gasoline). Car manufacturers and fuel produ

  5. Modelling strategic responses to car and fuel taxation

    NARCIS (Netherlands)

    Heijnen, P.; Kooreman, P.

    2006-01-01

    We develop a model to analyse the interactions between actors involved in car and fuel taxation: consumers, car producers, fuel producers and the government. Heterogeneous consumers choose between two versions of a car that differ in engine type (diesel or gasoline). Car manufacturers and fuel produ

  6. Modelling strategic responses to car and fuel taxation

    NARCIS (Netherlands)

    Heijnen, P.; Kooreman, P.

    We develop a model to analyse the interactions between actors involved in car and fuel taxation: consumers, car producers, fuel producers and the government. Heterogeneous consumers choose between two versions of a car that differ in engine type (diesel or gasoline). Car manufacturers and fuel

  7. Modeling Strategic Interactions to Car and Fuel Taxation

    NARCIS (Netherlands)

    Heijnen, P.; Kooreman, P.

    2006-01-01

    We develop a model to analyse the interactions between actors involved in car and fuel taxation: consumers, car producers, fuel producers and the government. Heterogeneous consumers choose between two versions of a car that differ in engine type (diesel or gasoline). Car manufacturers and fuel

  8. Mathematical Model of the Jet Engine Fuel System

    Science.gov (United States)

    Klimko, Marek

    2015-05-01

    The paper discusses the design of a simplified mathematical model of the jet (turbo-compressor) engine fuel system. The solution will be based on the regulation law, where the control parameter is a fuel mass flow rate and the regulated parameter is the rotational speed. A differential equation of the jet engine and also differential equations of other fuel system components (fuel pump, throttle valve, pressure regulator) will be described, with respect to advanced predetermined simplifications.

  9. Mathematical Model of the Jet Engine Fuel System

    Directory of Open Access Journals (Sweden)

    Klimko Marek

    2015-01-01

    Full Text Available The paper discusses the design of a simplified mathematical model of the jet (turbo-compressor engine fuel system. The solution will be based on the regulation law, where the control parameter is a fuel mass flow rate and the regulated parameter is the rotational speed. A differential equation of the jet engine and also differential equations of other fuel system components (fuel pump, throttle valve, pressure regulator will be described, with respect to advanced predetermined simplifications.

  10. Forecast of future aviation fuels: The model

    Science.gov (United States)

    Ayati, M. B.; Liu, C. Y.; English, J. M.

    1981-01-01

    A conceptual models of the commercial air transportation industry is developed which can be used to predict trends in economics, demand, and consumption. The methodology is based on digraph theory, which considers the interaction of variables and propagation of changes. Air transportation economics are treated by examination of major variables, their relationships, historic trends, and calculation of regression coefficients. A description of the modeling technique and a compilation of historic airline industry statistics used to determine interaction coefficients are included. Results of model validations show negligible difference between actual and projected values over the twenty-eight year period of 1959 to 1976. A limited application of the method presents forecasts of air tranportation industry demand, growth, revenue, costs, and fuel consumption to 2020 for two scenarios of future economic growth and energy consumption.

  11. On the modeling of fuel sprays

    Energy Technology Data Exchange (ETDEWEB)

    Bergstroem, Christer

    1997-12-01

    This report concerns on the modelling of fuel sprays in a non-combustible case using an own developed fuel spray code module. The spray code is made as an independent module to simplify the use of different gas flow solvers together with the spray module. This enables the possibility to use different turbulence models. In the report two turbulence models has been used, the standard k-{epsilon} and the LES (Large Eddy Simulation) model. The report presents results obtained from a sensitivity study of both numerical and physical parameters on an evaporating spray under diesel like conditions (light duty diesel engine) with the spray code module attached to a cylindrical gas phase flow solver. The results from the sensitivity analysis showed that these effects were not so pronounced as has been reported. It was suggested that this was due to the `easy` nature of the investigated case, where the flow field could be sufficiently resolved without violating the droplet void fraction criteria and break-up, collision and combustion that may increase the grid spacing sensitivity were not modelled. An investigation was performed to valuate the feasibility of using LES as turbulence model. Calculations of the initial phase of a developing jet were made and it was found that in the initial phase of the spray and the flow structure were similar to that of a spatially developing jet flow, which is in agreement with experimental observations. Results from LES calculations on a developing spray jet was also compared with k-{epsilon} based ones. This result showed that the spray-LES approach captured the transition from a laminar to a turbulent flow field with an increase in turbulent kinetic energy k along the injection direction 45 refs, 37 figs, 2 tabs

  12. A transient model to simulate HTPEM fuel cell impedance spectra

    DEFF Research Database (Denmark)

    Vang, Jakob Rabjerg; Andreasen, Søren Juhl; Kær, Søren Knudsen

    2012-01-01

    This paper presents a spatially resolved transient fuel cell model applied to the simulation of high temperature PEM fuel cell impedance spectra. The model is developed using a 2D finite volume method approach. The model is resolved along the channel and across the membrane. The model considers...

  13. Model of U3Si2 Fuel System using BISON Fuel Code

    Energy Technology Data Exchange (ETDEWEB)

    K. E. Metzger; T. W. Knight; R. L. Williamson

    2014-04-01

    This research considers the proposed advanced fuel system: U3Si2 combined with an advanced cladding. U3Si2 has a number of advantageous thermophysical properties, which motivate its use as an accident tolerant fuel. This preliminary model evaluates the behavior of U3Si2 using available thermophysical data to predict the cladding-fuel pellet temperature and stress using the fuel performance code: BISON. The preliminary results obtained from the U3Si2 fuel model describe the mechanism of Pellet-Clad Mechanical Interaction for this system while more extensive testing including creep testing of U3Si2 is planned for improved understanding of thermophysical properties for predicting fuel performance.

  14. Recent Advances in Enzymatic Fuel Cells: Experiments and Modeling

    Directory of Open Access Journals (Sweden)

    Ivan Ivanov

    2010-04-01

    Full Text Available Enzymatic fuel cells convert the chemical energy of biofuels into electrical energy. Unlike traditional fuel cell types, which are mainly based on metal catalysts, the enzymatic fuel cells employ enzymes as catalysts. This fuel cell type can be used as an implantable power source for a variety of medical devices used in modern medicine to administer drugs, treat ailments and monitor bodily functions. Some advantages in comparison to conventional fuel cells include a simple fuel cell design and lower cost of the main fuel cell components, however they suffer from severe kinetic limitations mainly due to inefficiency in electron transfer between the enzyme and the electrode surface. In this review article, the major research activities concerned with the enzymatic fuel cells (anode and cathode development, system design, modeling by highlighting the current problems (low cell voltage, low current density, stability will be presented.

  15. Modeling Of Proton Exchange Membrane Fuel Cell Systems

    DEFF Research Database (Denmark)

    Nielsen, Mads Pagh

    The objective of this doctoral thesis was to develop reliable steady-state and transient component models suitable to asses-, develop- and optimize proton exchange membrane (PEM) fuel cell systems. Several components in PEM fuel cell systems were characterized and modeled. The developed component...... cell systems. Consequences of indirectly fueling PEM stacks with hydrocarbons using reforming technology were investigated using a PEM stack model including CO poisoning kinetics and a transient Simulink steam reforming system model. Aspects regarding the optimization of PEM fuel cell systems...

  16. A mathematical prognosis model for pancreatic cancer patients receiving immunotherapy.

    Science.gov (United States)

    Li, Xuefang; Xu, Jian-Xin

    2016-10-07

    Pancreatic cancer is one of the most deadly types of cancer since it typically spreads rapidly and can seldom be detected in its early stage. Pancreatic cancer therapy is thus a challenging task, and appropriate prognosis or assessment for pancreatic cancer therapy is of critical importance. In this work, based on available clinical data in Niu et al. (2013) we develop a mathematical prognosis model that can predict the overall survival of pancreatic cancer patients who receive immunotherapy. The mathematical model incorporates pancreatic cancer cells, pancreatic stellate cells, three major classes of immune effector cells CD8+ T cells, natural killer cells, helper T cells, and two major classes of cytokines interleukin-2 (IL-2) and interferon-γ (IFN-γ). The proposed model describes the dynamic interaction between tumor and immune cells. In order for the model to be able to generate appropriate prognostic results for disease progression, the distribution and stability properties of equilibria in the mathematical model are computed and analysed in absence of treatments. In addition, numerical simulations for disease progression with or without treatments are performed. It turns out that the median overall survival associated with CIK immunotherapy is prolonged from 7 to 13months compared with the survival without treatment, this is consistent with the clinical data observed in Niu et al. (2013). The validity of the proposed mathematical prognosis model is thus verified. Our study confirms that immunotherapy offers a better prognosis for pancreatic cancer patients. As a direct extension of this work, various new therapy methods that are under exploration and clinical trials could be assessed or evaluated using the newly developed mathematical prognosis model.

  17. Modeling the Thermal Rocket Fuel Preparation Processes in the Launch Complex Fueling System

    Directory of Open Access Journals (Sweden)

    A. V. Zolin

    2015-01-01

    Full Text Available It is necessary to carry out fuel temperature preparation for space launch vehicles using hydrocarbon propellant components. A required temperature is reached with cooling or heating hydrocarbon fuel in ground facilities fuel storages. Fuel temperature preparing processes are among the most energy-intensive and lengthy processes that require the optimal technologies and regimes of cooling (heating fuel, which can be defined using the simulation of heat exchange processes for preparing the rocket fuel.The issues of research of different technologies and simulation of cooling processes of rocket fuel with liquid nitrogen are given in [1-10]. Diagrams of temperature preparation of hydrocarbon fuel, mathematical models and characteristics of cooling fuel with its direct contact with liquid nitrogen dispersed are considered, using the numerical solution of a system of heat transfer equations, in publications [3,9].Analytical models, allowing to determine the necessary flow rate and the mass of liquid nitrogen and the cooling (heating time fuel in specific conditions and requirements, are preferred for determining design and operational characteristics of the hydrocarbon fuel cooling system.A mathematical model of the temperature preparation processes is developed. Considered characteristics of these processes are based on the analytical solutions of the equations of heat transfer and allow to define operating parameters of temperature preparation of hydrocarbon fuel in the design and operation of the filling system of launch vehicles.The paper considers a technological system to fill the launch vehicles providing the temperature preparation of hydrocarbon gases at the launch site. In this system cooling the fuel in the storage tank before filling the launch vehicle is provided by hydrocarbon fuel bubbling with liquid nitrogen. Hydrocarbon fuel is heated with a pumping station, which provides fuel circulation through the heat exchanger-heater, with

  18. Mathematical Modeling of Fuel Pressure inside High Pressure Fuel Pipeline of Combination Electronic Unit Pump Fuel Injection System

    Directory of Open Access Journals (Sweden)

    Qaisar Hayat

    2013-08-01

    Full Text Available In order to completely understand the trend of pressure variations inside High Pressure (HP fuel pipeline of Combination Electronic Unit Pump (CEUP fuel injection system and study the impact of two major physical properties of fuel i.e., density and dynamic viscosity on pressure a 1D nonlinear dynamic mathematical model of fuel pressure inside pipeline using Wave Equation (WE has been developed in MATLAB using finite difference method. The developed model is based on the structural parameters of CEUP fuel injection system. The impact of two major physical properties of the fuel has been studied as a function of pressure at various operating conditions of diesel engine. Nearly 13.13 bars of increase in pressure is observed by increasing the density from 700 kg/m3 to 1000 kg/m3. Whereas an increase of viscosity from 2 kg/m.s to 6 kg/m.s results in decrease of pressures up to 44.16 bars. Pressure corrections in the mathematical model have been incorporated based on variations of these two fuel properties with the pressure. The resultant pressure profiles obtained from mathematical model at various distances along the pipeline are verified by correlating them with the profiles obtained from simulated AMESim numerical model of CEUP. The results show that MATLAB mathematical results are quite coherent with the AMESim simulated results and validate that the model is an effective tool for predicting pressure inside HP pipelines. The application of the this mathematical model with minute changes can therefore be extended to pressure modeling inside HP rail of Common Rail (CR fuel injection system.

  19. Atomic scale simulations for improved CRUD and fuel performance modeling

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Anders David Ragnar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cooper, Michael William Donald [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-06

    A more mechanistic description of fuel performance codes can be achieved by deriving models and parameters from atomistic scale simulations rather than fitting models empirically to experimental data. The same argument applies to modeling deposition of corrosion products on fuel rods (CRUD). Here are some results from publications in 2016 carried out using the CASL allocation at LANL.

  20. Combustion Characterization and Model Fuel Development for Micro-tubular Flame-assisted Fuel Cells.

    Science.gov (United States)

    Milcarek, Ryan J; Garrett, Michael J; Baskaran, Amrish; Ahn, Jeongmin

    2016-10-02

    Combustion based power generation has been accomplished for many years through a number of heat engine systems. Recently, a move towards small scale power generation and micro combustion as well as development in fuel cell research has created new means of power generation that combine solid oxide fuel cells with open flames and combustion exhaust. Instead of relying upon the heat of combustion, these solid oxide fuel cell systems rely on reforming of the fuel via combustion to generate syngas for electrochemical power generation. Procedures were developed to assess the combustion by-products under a wide range of conditions. While theoretical and computational procedures have been developed for assessing fuel-rich combustion exhaust in these applications, experimental techniques have also emerged. The experimental procedures often rely upon a gas chromatograph or mass spectrometer analysis of the flame and exhaust to assess the combustion process as a fuel reformer and means of heat generation. The experimental techniques developed in these areas have been applied anew for the development of the micro-tubular flame-assisted fuel cell. The protocol discussed in this work builds on past techniques to specify a procedure for characterizing fuel-rich combustion exhaust and developing a model fuel-rich combustion exhaust for use in flame-assisted fuel cell testing. The development of the procedure and its applications and limitations are discussed.

  1. New Mechanical Model for the Transmutation Fuel Performance Code

    Energy Technology Data Exchange (ETDEWEB)

    Gregory K. Miller

    2008-04-01

    A new mechanical model has been developed for implementation into the TRU fuel performance code. The new model differs from the existing FRAPCON 3 model, which it is intended to replace, in that it will include structural deformations (elasticity, plasticity, and creep) of the fuel. Also, the plasticity algorithm is based on the “plastic strain–total strain” approach, which should allow for more rapid and assured convergence. The model treats three situations relative to interaction between the fuel and cladding: (1) an open gap between the fuel and cladding, such that there is no contact, (2) contact between the fuel and cladding where the contact pressure is below a threshold value, such that axial slippage occurs at the interface, and (3) contact between the fuel and cladding where the contact pressure is above a threshold value, such that axial slippage is prevented at the interface. The first stage of development of the model included only the fuel. In this stage, results obtained from the model were compared with those obtained from finite element analysis using ABAQUS on a problem involving elastic, plastic, and thermal strains. Results from the two analyses showed essentially exact agreement through both loading and unloading of the fuel. After the cladding and fuel/clad contact were added, the model demonstrated expected behavior through all potential phases of fuel/clad interaction, and convergence was achieved without difficulty in all plastic analysis performed. The code is currently in stand alone form. Prior to implementation into the TRU fuel performance code, creep strains will have to be added to the model. The model will also have to be verified against an ABAQUS analysis that involves contact between the fuel and cladding.

  2. Modelling and modal properties of nuclear fuel assembly

    Directory of Open Access Journals (Sweden)

    Zeman V.

    2011-12-01

    Full Text Available The paper deals with the modelling and modal analysis of the hexagonal type nuclear fuel assembly. This very complicated mechanical system is created from the many beam type components shaped into spacer grids. The cyclic and central symmetry of the fuel rod package and load-bearing skeleton is advantageous for the fuel assembly decomposition into six identical revolved fuel rod segments, centre tube and skeleton linked by several spacer grids in horizontal planes. The derived mathematical model is used for the modal analysis of the Russian TVSA-T fuel assembly and validated in terms of experimentally determined natural frequencies, modes and static deformations caused by lateral force and torsional couple of forces. The presented model is the first necessary step for modelling of the nuclear fuel assembly vibration caused by different sources of excitation during the nuclear reactor VVER type operation.

  3. Modeling of constituent redistribution in U Pu Zr metallic fuel

    Science.gov (United States)

    Kim, Yeon Soo; Hayes, S. L.; Hofman, G. L.; Yacout, A. M.

    2006-12-01

    A computer model was developed to analyze constituent redistribution in U-Pu-Zr metallic nuclear fuels. Diffusion and thermochemical properties were parametrically determined to fit the postirradiation data from a fuel test performed in the Experimental Breeder Reactor II (EBR-II). The computer model was used to estimate redistribution profiles of fuels proposed for the conceptual designs of small modular fast reactors. The model results showed that the level of redistribution of the fuel constituents of the designs was similar to the measured data from EBR-II.

  4. Nuclear chemistry model of borated fuel crud

    Energy Technology Data Exchange (ETDEWEB)

    Sawicki, J.A. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada)

    2002-07-01

    Fuel crud deposits on Callaway Cycle 9 once-burnt high-axial offset anomaly (AOA {approx} -15%) feed assemblies revealed a complex 4-phase matted-layered morphology of a new type that is uncommon in pressurized water reactors [1-3]. The up to 140-{open_square}m-thick crud flakes consisted predominantly of insoluble needle-like particles of Ni-Fe oxy-borate Ni{sub 2}FeBO{sub 5} (bonaccordite) and granular precipitates of m-ZrO{sub 2} (baddeleyite), along with nickel oxide NiO (bunsenite) and minor amount of nickel ferrite NiFe{sub 2}O{sub 4} (trevorite). Furthermore, boron in crud flakes showed that the concentration of {sup 10}B had depleted to 10.2{+-}0.2%, as compared to its 20% natural isotopic abundance and its 17% end-of-cycle abundance in bulk coolant. The form and depth distribution of Ni{sub 2}FeBO{sub 5} and m-ZrO{sub 2} precipitates, as well as substantial {sup 10}B burn-up, point to a strongly alkaline environment at the clad surface of the high-duty fuel rods. This paper extends a nuclear chemistry model of heavily borated fuel crud deposits. The paper shows that the local nuclear heat and lithium buildup from {sup 10}B(n,{open_square}){sup 7}Li reactions may help to create hydrothermal and chemical conditions within the crud layer in favor of Ni{sub 2}FeBO{sub 5} formation and a ZrO{sub 2} dissolution-reprecipitation mechanism. Consistent with the model, the hydrothermal formation of Ni{sub 2}FeBO{sub 5} needles was recently proved to be possible in laboratory tests with aqueous NiO-Fe{sub 2}O{sub 3}-H{sub 3}BO{sub 3}-LiOH slurries, at temperatures only slightly exceeding 400 C. (author)

  5. Mechanical modeling of porous oxide fuel pellet A Test Problem

    Energy Technology Data Exchange (ETDEWEB)

    Nukala, Phani K [ORNL; Barai, Pallab [ORNL; Simunovic, Srdjan [ORNL; Ott, Larry J [ORNL

    2009-10-01

    A poro-elasto-plastic material model has been developed to capture the response of oxide fuels inside the nuclear reactors under operating conditions. Behavior of the oxide fuel and variation in void volume fraction under mechanical loading as predicted by the developed model has been reported in this article. The significant effect of void volume fraction on the overall stress distribution of the fuel pellet has also been described. An important oxide fuel issue that can have significant impact on the fuel performance is the mechanical response of oxide fuel pellet and clad system. Specifically, modeling the thermo-mechanical response of the fuel pellet in terms of its thermal expansion, mechanical deformation, swelling due to void formation and evolution, and the eventual contact of the fuel with the clad is of significant interest in understanding the fuel-clad mechanical interaction (FCMI). These phenomena are nonlinear and coupled since reduction in the fuel-clad gap affects thermal conductivity of the gap, which in turn affects temperature distribution within the fuel and the material properties of the fuel. Consequently, in order to accurately capture fuel-clad gap closure, we need to account for fuel swelling due to generation, retention, and evolution of fission gas in addition to the usual thermal expansion and mechanical deformation. Both fuel chemistry and microstructure also have a significant effect on the nucleation and growth of fission gas bubbles. Fuel-clad gap closure leading to eventual contact of the fuel with the clad introduces significant stresses in the clad, which makes thermo-mechanical response of the clad even more relevant. The overall aim of this test problem is to incorporate the above features in order to accurately capture fuel-clad mechanical interaction. Because of the complex nature of the problem, a series of test problems with increasing multi-physics coupling features, modeling accuracy, and complexity are defined with the

  6. Performance of fire behavior fuel models developed for the Rothermel Surface Fire Spread Model

    Science.gov (United States)

    Robert Ziel; W. Matt Jolly

    2009-01-01

    In 2005, 40 new fire behavior fuel models were published for use with the Rothermel Surface Fire Spread Model. These new models are intended to augment the original 13 developed in 1972 and 1976. As a compiled set of quantitative fuel descriptions that serve as input to the Rothermel model, the selected fire behavior fuel model has always been critical to the resulting...

  7. Software Requirements Specification Verifiable Fuel Cycle Simulation (VISION) Model

    Energy Technology Data Exchange (ETDEWEB)

    D. E. Shropshire; W. H. West

    2005-11-01

    The purpose of this Software Requirements Specification (SRS) is to define the top-level requirements for a Verifiable Fuel Cycle Simulation Model (VISION) of the Advanced Fuel Cycle (AFC). This simulation model is intended to serve a broad systems analysis and study tool applicable to work conducted as part of the AFCI (including costs estimates) and Generation IV reactor development studies.

  8. Modeling Of Proton Exchange Membrane Fuel Cell Systems

    DEFF Research Database (Denmark)

    Nielsen, Mads Pagh

    The objective of this doctoral thesis was to develop reliable steady-state and transient component models suitable to asses-, develop- and optimize proton exchange membrane (PEM) fuel cell systems. Several components in PEM fuel cell systems were characterized and modeled. The developed component...

  9. Proton exchange membrane fuel cells modeling

    CERN Document Server

    Gao, Fengge; Miraoui, Abdellatif

    2013-01-01

    The fuel cell is a potential candidate for energy storage and conversion in our future energy mix. It is able to directly convert the chemical energy stored in fuel (e.g. hydrogen) into electricity, without undergoing different intermediary conversion steps. In the field of mobile and stationary applications, it is considered to be one of the future energy solutions.Among the different fuel cell types, the proton exchange membrane (PEM) fuel cell has shown great potential in mobile applications, due to its low operating temperature, solid-state electrolyte and compactness.This book pre

  10. Development of 3D Oxide Fuel Mechanics Models

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, B. W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Casagranda, A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pitts, S. A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jiang, W. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-07-27

    This report documents recent work to improve the accuracy and robustness of the mechanical constitutive models used in the BISON fuel performance code. These developments include migration of the fuel mechanics models to be based on the MOOSE Tensor Mechanics module, improving the robustness of the smeared cracking model, implementing a capability to limit the time step size based on material model response, and improving the robustness of the return mapping iterations used in creep and plasticity models.

  11. Fuel Thermo-physical Characterization Project: Evaluation of Models to Calculate Thermal Diffusivity of Layered Composites

    Energy Technology Data Exchange (ETDEWEB)

    Burkes, Douglas [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Casella, Amanda J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gardner, Levi D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Casella, Andrew M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Huber, Tanja K. [Technische Universität München, Munich (Germany); Breitkreutz, Harald [Technische Universität München, Munich (Germany)

    2015-02-11

    The Office of Material Management and Minimization Fuel Thermo-physical Characterization Project at Pacific Northwest National Laboratory (PNNL) is tasked with using PNNL facilities and processes to receive irradiated low enriched uranium-molybdenum fuel plate samples and perform analyses in support of the Office of Material Management and Minimization Reactor Conversion Program. This work is in support of the Fuel Development Pillar that is managed by Idaho National Laboratory. A key portion of the scope associated with this project was to measure the thermal properties of fuel segments harvested from plates that were irradiated in the Advanced Test Reactor. Thermal diffusivity of samples prepared from the fuel segments was measured using laser flash analysis. Two models, one developed by PNNL and the other developed by the Technische Universität München (TUM), were evaluated to extract the thermal diffusivity of the uranium-molybdenum alloy from measurements made on the irradiated, layered composites. The experimental data of the “TC” irradiated fuel segment was evaluated using both models considering a three-layer and five-layer system. Both models are in acceptable agreement with one another and indicate that the zirconium diffusion barrier has a minimal impact on the overall thermal diffusivity of the monolithic U-Mo fuel.

  12. Fuel fragmentation model advances using TEXAS-V

    Energy Technology Data Exchange (ETDEWEB)

    Corradini, M.L.; El-Beshbeeshy, M.; Nilsuwankowsit, S.; Tang, J. [Wisconsin Univ., Madison, WI (United States). Dept. of Nuclear Engineering and Engineering Physics

    1998-01-01

    Because an energetic fuel-coolant interaction may be a safety hazard, experiments are being conducted to investigate the fuel-coolant mixing/quenching process (FARO) as well as the energetics of vapor explosion propagation for high temperature fuel melt simulants (KROTOS, WFCI, ZrEX). In both types of experiments, the dynamic breakup of the fuel is one of the key aspects that must be fundamentally understood to better estimate the magnitude of the mixing/quenching process or the explosion energetics. To aid our understanding the TEXAS fuel-coolant interaction computer model has been developed and is being used to analyze these experiments. Recently, the models for dynamic fuel fragmentation during the mixing and explosion phases of the FCI have been improved by further insights into these processes. The purpose of this paper is to describe these enhancements and to demonstrate their improvements by analysis of particular JRC FCI data. (author)

  13. MODELING NATURAL ATTENUATION OF FUELS WITH BIOPLUME III

    Science.gov (United States)

    A natural attenuation model that simulates the aerobic and anaerobic biodegradation of fuel hydrocarbons was developed. The resulting model, BIOPLUME III, demonstrates the importance of biodegradation in reducing contaminant concentrations in ground water. In hypothetical simulat...

  14. Experimental investigation and modeling of diesel engine fuel spray

    OpenAIRE

    Kolodnytska, R. V.; Karimi, K; Crua, C.; Heikal, M. R.; Sazhina, E. M.

    2008-01-01

    A model for spray penetration in diesel engines is suggested. It is based on momentum conservation for a realistic mass flow rate transient profile. The modelling approach is based on tracking of centre-of-fuel-mass (COFM) of injected diesel fuel. The model was validated for Bosch and Delphi injectors using the data obtained at Sir Harry Ricardo automotive centre, University of Brighton, UK. The model is shown to produce a good agreement with the experimental data until ...

  15. FAST: A combined NOC and transient fuel model for CANDU fuel

    Energy Technology Data Exchange (ETDEWEB)

    Prudil, A.; Lewis, B.J.; Chan, P.K., E-mail: Paul.Chan@rmc.ca [Royal Military College of Canada, Dept. of Chemistry and Chemical Engineering, Kingston, Ontario (Canada); Baschuk, J.J. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2013-07-01

    The Fuel And Sheath modelling Tool (FAST) is a fuel performance code that is being developed for both normal and transient operating conditions. FAST includes models for heat generation and transport, thermal-expansion, elastic strain, densification, fission product swelling, pellet relocation, contact, grain growth, fission gas release, gas and coolant pressure and sheath creep. These models have been implemented using the Comsol finite-element platform. The equations are solved on a two-dimensional (radial-axial) geometry of a fuel pellet and sheath. FAST has undergone a proof of concept validation against experimental data and comparison to the ELESTRES and ELOCA fuel performance codes. The results show excellent agreement with experimental measurements and the above stated IST- codes. (author)

  16. Gas-Cooled Reactor Programs annual progress report for period ending December 31, 1973. [HTGR fuel reprocessing, fuel fabrication, fuel irradiation, core materials, and fission product distribution; GCFR fuel irradiation and steam generator modeling

    Energy Technology Data Exchange (ETDEWEB)

    Kasten, P.R.; Coobs, J.H.; Lotts, A.L.

    1976-04-01

    Progress is summarized in studies relating to HTGR fuel reprocessing, refabrication, and recycle; HTGR fuel materials development and performance testing; HTGR PCRV development; HTGR materials investigations; HTGR fuel chemistry; HTGR safety studies; and GCFR irradiation experiments and steam generator modeling.

  17. Preliminary Modeling of Accident Tolerant Fuel Concepts under Accident Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Gamble, Kyle A.; Hales, Jason D.

    2016-12-01

    The catastrophic events that occurred at the Fukushima-Daiichi nuclear power plant in 2011 have led to widespread interest in research of alternative fuels and claddings that are proposed to be accident tolerant. Thus, the United States Department of Energy through its NEAMS (Nuclear Energy Advanced Modeling and Simulation) program has funded an Accident Tolerant Fuel (ATF) High Impact Problem (HIP). The ATF HIP is funded for a three-year period. The purpose of the HIP is to perform research into two potential accident tolerant concepts and provide an in-depth report to the Advanced Fuels Campaign (AFC) describing the behavior of the concepts, both of which are being considered for inclusion in a lead test assembly scheduled for placement into a commercial reactor in 2022. The initial focus of the HIP is on uranium silicide fuel and iron-chromium-aluminum (FeCrAl) alloy cladding. Utilizing the expertise of three national laboratory participants (INL, LANL, and ANL) a comprehensive mulitscale approach to modeling is being used including atomistic modeling, molecular dynamics, rate theory, phase-field, and fuel performance simulations. In this paper, we present simulations of two proposed accident tolerant fuel systems: U3Si2 fuel with Zircaloy-4 cladding, and UO2 fuel with FeCrAl cladding. The simulations investigate the fuel performance response of the proposed ATF systems under Loss of Coolant and Station Blackout conditions using the BISON code. Sensitivity analyses are completed using Sandia National Laboratories’ DAKOTA software to determine which input parameters (e.g., fuel specific heat) have the greatest influence on the output metrics of interest (e.g., fuel centerline temperature). Early results indicate that each concept has significant advantages as well as areas of concern. Further work is required prior to formulating the proposition report for the Advanced Fuels Campaign.

  18. Device and materials modeling in PEM fuel cells

    CERN Document Server

    Promislow, Keith

    2009-01-01

    Device and Materials Modeling in PEM Fuel Cells is a specialized text that compiles the mathematical details and results of both device and materials modeling in a single volume. Proton exchange membrane (PEM) fuel cells will likely have an impact on our way of life similar to the integrated circuit. The potential applications range from the micron scale to large scale industrial production. Successful integration of PEM fuel cells into the mass market will require new materials and a deeper understanding of the balance required to maintain various operational states. This book contains articles from scientists who contribute to fuel cell models from both the materials and device perspectives. Topics such as catalyst layer performance and operation, reactor dynamics, macroscopic transport, and analytical models are covered under device modeling. Materials modeling include subjects relating to the membrane and the catalyst such as proton conduction, atomistic structural modeling, quantum molecular dynamics, an...

  19. Crustal structure beneath northeast India inferred from receiver function modeling

    Science.gov (United States)

    Borah, Kajaljyoti; Bora, Dipok K.; Goyal, Ayush; Kumar, Raju

    2016-09-01

    We estimated crustal shear velocity structure beneath ten broadband seismic stations of northeast India, by using H-Vp/Vs stacking method and a non-linear direct search approach, Neighbourhood Algorithm (NA) technique followed by joint inversion of Rayleigh wave group velocity and receiver function, calculated from teleseismic earthquakes data. Results show significant variations of thickness, shear velocities (Vs) and Vp/Vs ratio in the crust of the study region. The inverted shear wave velocity models show crustal thickness variations of 32-36 km in Shillong Plateau (North), 36-40 in Assam Valley and ∼44 km in Lesser Himalaya (South). Average Vp/Vs ratio in Shillong Plateau is less (1.73-1.77) compared to Assam Valley and Lesser Himalaya (∼1.80). Average crustal shear velocity beneath the study region varies from 3.4 to 3.5 km/s. Sediment structure beneath Shillong Plateau and Assam Valley shows 1-2 km thick sediment layer with low Vs (2.5-2.9 km/s) and high Vp/Vs ratio (1.8-2.1), while it is observed to be of greater thickness (4 km) with similar Vs and high Vp/Vs (∼2.5) in RUP (Lesser Himalaya). Both Shillong Plateau and Assam Valley show thick upper and middle crust (10-20 km), and thin (4-9 km) lower crust. Average Vp/Vs ratio in Assam Valley and Shillong Plateau suggest that the crust is felsic-to-intermediate and intermediate-to-mafic beneath Shillong Plateau and Assam Valley, respectively. Results show that lower crust rocks beneath the Shillong Plateau and Assam Valley lies between mafic granulite and mafic garnet granulite.

  20. Fuel cycle assessment: A compendium of models, methodologies, and approaches

    Energy Technology Data Exchange (ETDEWEB)

    1994-07-01

    The purpose of this document is to profile analytical tools and methods which could be used in a total fuel cycle analysis. The information in this document provides a significant step towards: (1) Characterizing the stages of the fuel cycle. (2) Identifying relevant impacts which can feasibly be evaluated quantitatively or qualitatively. (3) Identifying and reviewing other activities that have been conducted to perform a fuel cycle assessment or some component thereof. (4) Reviewing the successes/deficiencies and opportunities/constraints of previous activities. (5) Identifying methods and modeling techniques/tools that are available, tested and could be used for a fuel cycle assessment.

  1. Modeling of large-scale oxy-fuel combustion processes

    DEFF Research Database (Denmark)

    Yin, Chungen

    2012-01-01

    , among which radiative heat transfer under oxy-fuel conditions is one of the fundamental issues. This paper demonstrates the nongray-gas effects in modeling of large-scale oxy-fuel combustion processes. Oxy-fuel combustion of natural gas in a 609MW utility boiler is numerically studied, in which....... The simulation results show that the gray and non-gray calculations of the same oxy-fuel WSGGM make distinctly different predictions in the wall radiative heat transfer, incident radiative flux, radiative source, gas temperature and species profiles. In relative to the non-gray implementation, the gray...

  2. Modeling of Flow in Nuclear Reactor Fuel Cell Outlet

    Directory of Open Access Journals (Sweden)

    František URBAN

    2010-12-01

    Full Text Available Safe and effective load of nuclear reactor fuel cells demands qualitative and quantitative analysis of relations between coolant temperature in fuel cell outlet temperature measured by thermocouple and middle temperature of coolant in thermocouple plane position. In laboratory at Insitute of thermal power engineering of the Slovak University of Technology in Bratislava was installed an experimental physical fuel cell model of VVER 440 nuclear power plant with V 213 nuclear reactors. Objective of measurements on physical model was temperature and velocity profiles analysis in the fuel cell outlet. In this paper the measured temperature and velocity profiles are compared with the results of CFD simulation of fuel cell physical model coolant flow.

  3. MODELING OF FUEL SPRAY CHARACTERISTICS AND DIESEL COMBUSTION CHAMBER PARAMETERS

    Directory of Open Access Journals (Sweden)

    G. M. Kukharonak

    2011-01-01

    Full Text Available The computer model for coordination of fuel spray characteristics with diesel combustion chamber parameters has been created in the paper.  The model allows to observe fuel sprays  develоpment in diesel cylinder at any moment of injection, to calculate characteristics of fuel sprays with due account of a shape and dimensions of a combustion chamber, timely to change fuel injection characteristics and supercharging parameters, shape and dimensions of a combustion chamber. Moreover the computer model permits to determine parameters of holes in an injector nozzle that provides the required fuel sprays characteristics at the stage of designing a diesel engine. Combustion chamber parameters for 4ЧН11/12.5 diesel engine have been determined in the paper.

  4. Model-based control of fuel cells (2): Optimal efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Golbert, Joshua; Lewin, Daniel R. [PSE Research Group, Wolfson Department of Chemical Engineering, Technion IIT, Haifa 32000 (Israel)

    2007-11-08

    A dynamic PEM fuel cell model has been developed, taking into account spatial dependencies of voltage, current, material flows, and temperatures. The voltage, current, and therefore, the efficiency are dependent on the temperature and other variables, which can be optimized on the fly to achieve optimal efficiency. In this paper, we demonstrate that a model predictive controller, relying on a reduced-order approximation of the dynamic PEM fuel cell model can satisfy setpoint changes in the power demand, while at the same time, minimize fuel consumption to maximize the efficiency. The main conclusion of the paper is that by appropriate formulation of the objective function, reliable optimization of the performance of a PEM fuel cell can be performed in which the main tunable parameter is the prediction and control horizons, V and U, respectively. We have demonstrated that increased fuel efficiency can be obtained at the expense of slower responses, by increasing the values of these parameters. (author)

  5. Proceedings of the NETL Workshop on Fuel Cell Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Randall S. Gemmen; J. R. Selman

    2000-04-18

    This workshop was the first U.S. DOE sponsored meeting devoted to fuel cell modeling. The workshop was attended by over 45 people from industry, universities, and the government. The goals of the meeting were to assess the status of fuel cell modeling, and determine how new developments in fuel cell modeling can improve cell design, stack design, and power system design. The primary focus was on cell and stack modeling. Following a review of DOE/NETL fuel cell related programs and activities, Professor Robert Selman (Illinois Institute of Technology) kicked off the technical portion of the workshop by presenting an overview of fuel cell phenomena and the status of fuel cell modeling. This overview provided the necessary background for establishing a common framework for discussing fuel cell modeling. A distinction was made between micro modeling, electrode modeling, cell modeling, stack modeling, and system modeling. It was proposed that all modeling levels be supported for further development. In addition, due to significant advances being made outside the U.S., it was proposed that dialog/exchange with other international researchers be established. Following the Overview Session, eight leading researchers in modeling gave individual presentations. These presentations provided additional information on the status and present direction of model developments. All these presentations can be found in Attachment A. Before the workshop, a survey was sent out requesting comments from the attendees. Results from this survey can be found in Attachment B. This survey was then used as initial talking points at the individual breakout sessions on the afternoon of the workshop. Breakouts were organized by microfundamental modeling, cell modeling, stack modeling, and systems modeling.

  6. MELCOR Modeling of Air-Cooled PWR Spent Fuel Assemblies in Water empty Fuel Pools

    Energy Technology Data Exchange (ETDEWEB)

    Herranz, L. E.; Lopez, C.

    2013-07-01

    The OECD Spent Fuel Project (SFP) investigated fuel degradation in case of a complete Loss-Of- Coolant-Accident in a PWR spent fuel pool. Analyses of the SFP PWR ignition tests have been conducted with the 1.86.YT.3084.SFP MELCOR version developed by SNL. The main emphasis has been placed on assessing the MELCOR predictive capability to get reasonable estimates of time-to-ignition and fire front propagation under two configurations: hot neighbor (i.e., adiabatic scenario) and cold neighbor (i.e., heat transfer to adjacent fuel assemblies). A detailed description of hypotheses and approximations adopted in the MELCOR model are provided in the paper. MELCOR results accuracy was notably different between both scenarios. The reasons are highlighted in the paper and based on the results understanding a set of remarks concerning scenarios modeling is given.

  7. 40 CFR 600.207-93 - Calculation of fuel economy values for a model type.

    Science.gov (United States)

    2010-07-01

    ... base level. (7) For alcohol dual fuel automobiles and natural gas dual fuel automobiles the procedures... combined fuel economy values from the tests performed using gasoline or diesel test fuel. (ii) Calculate... economy values for the model type. (5) For alcohol dual fuel automobiles and natural gas dual fuel...

  8. Input modelling for subchannel analysis of CANFLEX fuel bundle

    Energy Technology Data Exchange (ETDEWEB)

    Park, Joo Hwan; Jun, Ji Su; Suk, Ho Chun [Korea Atomic Energy Research Institute, Taejon (Korea)

    1998-06-01

    This report describs the input modelling for subchannel analysis of CANFLEX fuel bundle using CASS(Candu thermalhydraulic Analysis by Subchannel approacheS) code which has been developed for subchannel analysis of CANDU fuel channel. CASS code can give the different calculation results according to users' input modelling. Hence, the objective of this report provide the background information of input modelling, the accuracy of input data and gives the confidence of calculation results. (author). 11 refs., 3 figs., 4 tabs.

  9. HEISHI: A fuel performance model for space nuclear applications

    Energy Technology Data Exchange (ETDEWEB)

    Young, M.F.

    1994-08-01

    HEISHI is a Fortran computer model designed to aid in analysis, prediction, and optimization of fuel characteristics for use in Space Nuclear Thermal Propulsion (SNTP). Calculational results include fission product release rate, fuel failure fraction, mode of fuel failure, stress-strain state, and fuel material morphology. HEISHI contains models for decay chain calculations of retained and released fission products, based on an input power history and release coefficients. Decay chain parameters such as direct fission yield, decay rates, and branching fractions are obtained from a database. HEISHI also contains models for stress-strain behavior of multilayered fuel particles with creep and differential thermal expansion effects, transient particle temperature profile, grain growth, and fuel particle failure fraction. Grain growth is treated as a function of temperature; the failure fraction depends on the coating tensile strength, which in turn is a function of grain size. The HEISHI code is intended for use in analysis of coated fuel particles for use in particle bed reactors; however, much of the code is geometry-independent and applicable to fuel geometries other than spherical.

  10. Macroscopic Modeling of Transport Phenomena in Direct Methanol Fuel Cells

    DEFF Research Database (Denmark)

    Olesen, Anders Christian

    An increasing need for energy efficiency and high energy density has sparked a growing interest in direct methanol fuel cells for portable power applications. This type of fuel cell directly generates electricity from a fuel mixture consisting of methanol and water. Although this technology...... for studying their transport. In this PhD dissertation the macroscopic transport phenomena governing direct methanol fuel cell operation are analyzed, discussed and modeled using the two-fluid approach in the computational fluid dynamics framework of CFX 14. The overall objective of this work is to extend...... the present fundamental understanding of direct methanol fuel cell operation by developing a three-dimensional, two-phase, multi-component, non-isotherm mathematical model including detailed non-ideal thermodynamics, non-equilibrium phase change and non-equilibrium sorption-desorption of methanol and water...

  11. HTR Spherical Super Lattice Model for Equilibrium Fuel Cycle Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gray S. Cahng

    2005-09-01

    Advanced High Temperature gas-cooled Reactors (HTR) currently being developed (GFR, VHTR - Very High Temperature gas-cooled Reactor, PBMR, and GT-MHR) are able to achieve a simplification of safety through reliance on innovative features and passive systems. One of the innovative features in these HTRs is reliance on ceramic-coated fuel particles to retain the fission products even under extreme accident conditions. The effect of the random fuel kernel distribution in the fuel pebble / block is addressed through the use of the Dancoff correction factor in the resonance treatment. In addition, the Dancoff correction factor is a function of burnup and fuel kernel packing factor, which requires that the Dancoff correction factor be updated during Equilibrium Fuel Cycle (EqFC) analysis. Although HTR fuel is rather homogeneously dispersed in the fuel graphite matrix, the heterogeneity effects in between fuel kernels and pebbles cannot be ignored. The double-heterogeneous lattice model recently developed at the Idaho National Engineering and Environmental Laboratory (INEEL) contains tens of thousands of cubic fuel kernel cells, which makes it very difficult to deplete the fuel, kernel by kernel (KbK), for the EqFC analysis. In addition, it is not possible to preserve the cubic size and packing factor in a spherical fuel pebble. To avoid these difficulties, a newly developed and validated HTR pebble-bed Kernel-by-Kernel spherical (KbK-sph) model, has been developed and verified in this study. The objective of this research is to introduce the KbK-sph model and super whole Pebble lattice model (PLM). The verified double-heterogeneous KbK-sph and pebble homogeneous lattice model (HLM) are used for the fuel burnup chracteristics analysis and important safety parameters validation. This study summarizes and compares the KbK-sph and HLM burnup analyzed results. Finally, we discus the Monte-Carlo coupling with a fuel depletion and buildup code - Origen-2 as a fuel burnup

  12. Advanced modeling of oxy-fuel combustion of natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Chungen Yin

    2011-01-15

    The main goal of this small-scale project is to investigate oxy-combustion of natural gas (NG) through advanced modeling, in which radiation, chemistry and mixing will be reasonably resolved. 1) A state-of-the-art review was given regarding the latest R and D achievements and status of oxy-fuel technology. The modeling and simulation status and achievements in the field of oxy-fuel combustion were also summarized; 2) A computer code in standard c++, using the exponential wide band model (EWBM) to evaluate the emissivity and absorptivity of any gas mixture at any condition, was developed and validated in detail against data in literature. A new, complete, and accurate WSGGM, applicable to both air-fuel and oxy-fuel combustion modeling and applicable to both gray and non-gray calculation, was successfully derived, by using the validated EWBM code as the reference mode. The new WSGGM was implemented in CFD modeling of two different oxy-fuel furnaces, through which its great, unique advantages over the currently most widely used WSGGM were demonstrated. 3) Chemical equilibrium calculations were performed for oxy-NG flame and air-NG flame, in which dissociation effects were considered to different degrees. Remarkable differences in oxy-fuel and air-fuel combustion were revealed, and main intermediate species that play key roles in oxy-fuel flames were identified. Different combustion mechanisms are compared, e.g., the most widely used 2-step global mechanism, refined 4-step global mechanism, a global mechanism developed for oxy-fuel using detailed chemical kinetic modeling (CHEMKIN) as reference. 4) Over 15 CFD simulations were done for oxy-NG combustion, in which radiation, chemistry, mixing, turbulence-chemistry interactions, and so on were thoroughly investigated. Among all the simulations, RANS combined with 2-step and refined 4-step mechanism, RANS combined with CHEMKIN-based new global mechanism for oxy-fuel modeling, and LES combined with different combustion

  13. VISION User Guide - VISION (Verifiable Fuel Cycle Simulation) Model

    Energy Technology Data Exchange (ETDEWEB)

    Jacob J. Jacobson; Robert F. Jeffers; Gretchen E. Matthern; Steven J. Piet; Benjamin A. Baker; Joseph Grimm

    2009-08-01

    The purpose of this document is to provide a guide for using the current version of the Verifiable Fuel Cycle Simulation (VISION) model. This is a complex model with many parameters; the user is strongly encouraged to read this user guide before attempting to run the model. This model is an R&D work in progress and may contain errors and omissions. It is based upon numerous assumptions. This model is intended to assist in evaluating “what if” scenarios and in comparing fuel, reactor, and fuel processing alternatives at a systems level for U.S. nuclear power. The model is not intended as a tool for process flow and design modeling of specific facilities nor for tracking individual units of fuel or other material through the system. The model is intended to examine the interactions among the components of a fuel system as a function of time varying system parameters; this model represents a dynamic rather than steady-state approximation of the nuclear fuel system. VISION models the nuclear cycle at the system level, not individual facilities, e.g., “reactor types” not individual reactors and “separation types” not individual separation plants. Natural uranium can be enriched, which produces enriched uranium, which goes into fuel fabrication, and depleted uranium (DU), which goes into storage. Fuel is transformed (transmuted) in reactors and then goes into a storage buffer. Used fuel can be pulled from storage into either separation of disposal. If sent to separations, fuel is transformed (partitioned) into fuel products, recovered uranium, and various categories of waste. Recycled material is stored until used by its assigned reactor type. Note that recovered uranium is itself often partitioned: some RU flows with recycled transuranic elements, some flows with wastes, and the rest is designated RU. RU comes out of storage if needed to correct the U/TRU ratio in new recycled fuel. Neither RU nor DU are designated as wastes. VISION is comprised of several

  14. THE CRUSTAL STRUCTURE OF ELLESMERE ISLAND FROM RECEIVER FUNCTION MODELLING

    DEFF Research Database (Denmark)

    Schiffer, Christian; Stephenson, Randell Alexander; Oakey, Gordon

    . Preliminary results give estimates of Moho depths and crustal velocity structure and these are discussed with a focus on the relationship to topography, regional geological units and fault zones. The receiver functions reveal crustal roots underneath the Victoria and Albert Mountains (45km) and the Grantland...

  15. LG Solid Oxide Fuel Cell (SOFC) Model Development

    Energy Technology Data Exchange (ETDEWEB)

    Haberman, Ben [LG Fuel Cell Systems Inc., North Canton, OH (United States); Martinez-Baca, Carlos [LG Fuel Cell Systems Inc., North Canton, OH (United States); Rush, Greg [LG Fuel Cell Systems Inc., North Canton, OH (United States)

    2013-05-31

    This report presents a summary of the work performed by LG Fuel Cell Systems Inc. during the project LG Solid Oxide Fuel Cell (SOFC) Model Development (DOE Award Number: DE-FE0000773) which commenced on October 1, 2009 and was completed on March 31, 2013. The aim of this project is for LG Fuel Cell Systems Inc. (formerly known as Rolls-Royce Fuel Cell Systems (US) Inc.) (LGFCS) to develop a multi-physics solid oxide fuel cell (SOFC) computer code (MPC) for performance calculations of the LGFCS fuel cell structure to support fuel cell product design and development. A summary of the initial stages of the project is provided which describes the MPC requirements that were developed and the selection of a candidate code, STAR-CCM+ (CD-adapco). This is followed by a detailed description of the subsequent work program including code enhancement and model verification and validation activities. Details of the code enhancements that were implemented to facilitate MPC SOFC simulations are provided along with a description of the models that were built using the MPC and validated against experimental data. The modeling work described in this report represents a level of calculation detail that has not been previously available within LGFCS.

  16. PEM fuel cell modeling and simulation using Matlab

    CERN Document Server

    Spiegel, Colleen

    2011-01-01

    Although, the basic concept of a fuel cell is quite simple, creating new designs and optimizing their performance takes serious work and a mastery of several technical areas. PEM Fuel Cell Modeling and Simulation Using Matlab, provides design engineers and researchers with a valuable tool for understanding and overcoming barriers to designing and building the next generation of PEM Fuel Cells. With this book, engineers can test components and verify designs in the development phase, saving both time and money.Easy to read and understand, this book provides design and modelling tips for

  17. Transient heat conduction in a pebble fuel applying fractional model

    Energy Technology Data Exchange (ETDEWEB)

    Gomez A, R.; Espinosa P, G. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Area de Ingenieria en Recursos Energeticos, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico)], e-mail: gepe@xanum.uam.mx

    2009-10-15

    In this paper we presents the equation of thermal diffusion of temporary-fractional order in the one-dimensional space in spherical coordinates, with the objective to analyze the heat transference between the fuel and coolant in a fuel element of a Pebble Bed Modular Reactor. The pebble fuel is the heterogeneous system made by microsphere constitutes by U O, pyrolytic carbon and silicon carbide mixed with graphite. To describe the heat transfer phenomena in the pebble fuel we applied a constitutive law fractional (Non-Fourier) in order to analyze the behaviour transient of the temperature distribution in the pebble fuel with anomalous thermal diffusion effects a numerical model is developed. (Author)

  18. Receiver Prejudice and Model Ethnicity: Impact on Advertising Effectiveness.

    Science.gov (United States)

    Lai, Hsiu-Chen Sandra; And Others

    1990-01-01

    Assesses the effect of model ethnicity on prejudiced respondents, and thus on advertising effectiveness. Finds that, for the most part, use of Asian models does not cause prejudiced respondents to evaluate a product or advertisement more negatively than when White models are used. (SR)

  19. Receiver Prejudice and Model Ethnicity: Impact on Advertising Effectiveness.

    Science.gov (United States)

    Lai, Hsiu-Chen Sandra; And Others

    1990-01-01

    Assesses the effect of model ethnicity on prejudiced respondents, and thus on advertising effectiveness. Finds that, for the most part, use of Asian models does not cause prejudiced respondents to evaluate a product or advertisement more negatively than when White models are used. (SR)

  20. 42 CFR Appendix to Part 54a - Model Notice of Individuals Receiving Substance Abuse Services

    Science.gov (United States)

    2010-10-01

    ..., ET SEQ., FOR SUBSTANCE ABUSE PREVENTION AND TREATMENT SERVICES Pt. 54a, App. Appendix to Part 54a—Model Notice of Individuals Receiving Substance Abuse Services Model Notice to Individuals Receiving Substance Abuse Services No provider of substance abuse services receiving Federal funds from the...

  1. System level modeling and component level control of fuel cells

    Science.gov (United States)

    Xue, Xingjian

    This dissertation investigates the fuel cell systems and the related technologies in three aspects: (1) system-level dynamic modeling of both PEM fuel cell (PEMFC) and solid oxide fuel cell (SOFC); (2) condition monitoring scheme development of PEM fuel cell system using model-based statistical method; and (3) strategy and algorithm development of precision control with potential application in energy systems. The dissertation first presents a system level dynamic modeling strategy for PEM fuel cells. It is well known that water plays a critical role in PEM fuel cell operations. It makes the membrane function appropriately and improves the durability. The low temperature operating conditions, however, impose modeling difficulties in characterizing the liquid-vapor two phase change phenomenon, which becomes even more complex under dynamic operating conditions. This dissertation proposes an innovative method to characterize this phenomenon, and builds a comprehensive model for PEM fuel cell at the system level. The model features the complete characterization of multi-physics dynamic coupling effects with the inclusion of dynamic phase change. The model is validated using Ballard stack experimental result from open literature. The system behavior and the internal coupling effects are also investigated using this model under various operating conditions. Anode-supported tubular SOFC is also investigated in the dissertation. While the Nernst potential plays a central role in characterizing the electrochemical performance, the traditional Nernst equation may lead to incorrect analysis results under dynamic operating conditions due to the current reverse flow phenomenon. This dissertation presents a systematic study in this regard to incorporate a modified Nernst potential expression and the heat/mass transfer into the analysis. The model is used to investigate the limitations and optimal results of various operating conditions; it can also be utilized to perform the

  2. Macro Level Modeling of a Tubular Solid Oxide Fuel Cell

    Directory of Open Access Journals (Sweden)

    Farshid Zabihian

    2010-11-01

    Full Text Available This paper presents a macro-level model of a solid oxide fuel cell (SOFC stack implemented in Aspen Plus® for the simulation of SOFC system. The model is 0-dimensional and accepts hydrocarbon fuels such as reformed natural gas, with user inputs of current density, fuel and air composition, flow rates, temperature, pressure, and fuel utilization factor. The model outputs the composition of the exhaust, work produced, heat available for the fuel reformer, and electrochemical properties of SOFC for model validation. It was developed considering the activation, concentration, and ohmic losses to be the main over-potentials within the SOFC, and mathematical expressions for these were chosen based on available studies in the literature. The model also considered the water shift reaction of CO and the methane reforming reaction. The model results were validated using experimental data from Siemens Westinghouse. The results showed that the model could capture the operating pressure and temperature dependency of the SOFC performance successfully in an operating range of 1–15 atm for pressure and 900 °C–1,000 °C for temperature. Furthermore, a sensitivity analysis was performed to identify the model constants and input parameters that impacted the over-potentials.

  3. The FIT Model - Fuel-cycle Integration and Tradeoffs

    Energy Technology Data Exchange (ETDEWEB)

    Steven J. Piet; Nick R. Soelberg; Samuel E. Bays; Candido Pereira; Layne F. Pincock; Eric L. Shaber; Meliisa C Teague; Gregory M Teske; Kurt G Vedros

    2010-09-01

    All mass streams from fuel separation and fabrication are products that must meet some set of product criteria – fuel feedstock impurity limits, waste acceptance criteria (WAC), material storage (if any), or recycle material purity requirements such as zirconium for cladding or lanthanides for industrial use. These must be considered in a systematic and comprehensive way. The FIT model and the “system losses study” team that developed it [Shropshire2009, Piet2010] are an initial step by the FCR&D program toward a global analysis that accounts for the requirements and capabilities of each component, as well as major material flows within an integrated fuel cycle. This will help the program identify near-term R&D needs and set longer-term goals. The question originally posed to the “system losses study” was the cost of separation, fuel fabrication, waste management, etc. versus the separation efficiency. In other words, are the costs associated with marginal reductions in separations losses (or improvements in product recovery) justified by the gains in the performance of other systems? We have learned that that is the wrong question. The right question is: how does one adjust the compositions and quantities of all mass streams, given uncertain product criteria, to balance competing objectives including cost? FIT is a method to analyze different fuel cycles using common bases to determine how chemical performance changes in one part of a fuel cycle (say used fuel cooling times or separation efficiencies) affect other parts of the fuel cycle. FIT estimates impurities in fuel and waste via a rough estimate of physics and mass balance for a set of technologies. If feasibility is an issue for a set, as it is for “minimum fuel treatment” approaches such as melt refining and AIROX, it can help to make an estimate of how performances would have to change to achieve feasibility.

  4. The FIT Model - Fuel-cycle Integration and Tradeoffs

    Energy Technology Data Exchange (ETDEWEB)

    Steven J. Piet; Nick R. Soelberg; Samuel E. Bays; Candido Pereira; Layne F. Pincock; Eric L. Shaber; Meliisa C Teague; Gregory M Teske; Kurt G Vedros

    2010-09-01

    All mass streams from fuel separation and fabrication are products that must meet some set of product criteria – fuel feedstock impurity limits, waste acceptance criteria (WAC), material storage (if any), or recycle material purity requirements such as zirconium for cladding or lanthanides for industrial use. These must be considered in a systematic and comprehensive way. The FIT model and the “system losses study” team that developed it [Shropshire2009, Piet2010] are an initial step by the FCR&D program toward a global analysis that accounts for the requirements and capabilities of each component, as well as major material flows within an integrated fuel cycle. This will help the program identify near-term R&D needs and set longer-term goals. The question originally posed to the “system losses study” was the cost of separation, fuel fabrication, waste management, etc. versus the separation efficiency. In other words, are the costs associated with marginal reductions in separations losses (or improvements in product recovery) justified by the gains in the performance of other systems? We have learned that that is the wrong question. The right question is: how does one adjust the compositions and quantities of all mass streams, given uncertain product criteria, to balance competing objectives including cost? FIT is a method to analyze different fuel cycles using common bases to determine how chemical performance changes in one part of a fuel cycle (say used fuel cooling times or separation efficiencies) affect other parts of the fuel cycle. FIT estimates impurities in fuel and waste via a rough estimate of physics and mass balance for a set of technologies. If feasibility is an issue for a set, as it is for “minimum fuel treatment” approaches such as melt refining and AIROX, it can help to make an estimate of how performances would have to change to achieve feasibility.

  5. Modeling of Proton-Conducting Solid Oxide Fuel Cells Fueled with Syngas

    Directory of Open Access Journals (Sweden)

    Meng Ni

    2014-07-01

    Full Text Available Solid oxide fuel cells (SOFCs with proton conducting electrolyte (H-SOFCs are promising power sources for stationary applications. Compared with other types of fuel cells, one distinct feature of SOFC is their fuel flexibility. In this study, a 2D model is developed to investigate the transport and reaction in an H-SOFC fueled with syngas, which can be produced from conventional natural gas or renewable biomass. The model fully considers the fluid flow, mass transfer, heat transfer and reactions in the H-SOFC. Parametric studies are conducted to examine the physical and chemical processes in H-SOFC with a focus on how the operating parameters affect the H-SOFC performance. It is found that the presence of CO dilutes the concentration of H2, thus decreasing the H-SOFC performance. With typical syngas fuel, adding H2O cannot enhance the performance of the H-SOFC, although water gas shift reaction can facilitate H2 production.

  6. Models for fuel rod behaviour at high burnup

    Energy Technology Data Exchange (ETDEWEB)

    Jernkvist, Lars O.; Massih, Ali R. [Quantum Technologies AB, Uppsala Science Park, Uppsala (Sweden)

    2004-12-01

    This report deals with release of fission product gases and irradiation-induced restructuring in uranium dioxide nuclear fuel. Waterside corrosion of zirconium alloy clad tubes to light water reactor fuel rods is also discussed. Computational models, suitable for implementation in the FRAPCON-3.2 computer code, are proposed for these potentially life-limiting phenomena. Hence, an integrated model for the calculation or thermal fission gas release by intragranular diffusion, gas trapping in grain boundaries, irradiation-induced re-solution, grain boundary saturation, and grain boundary sweeping in UO{sub 2} fuel, under time varying temperature loads, is formulated. After a brief review of the status of thermal fission gas release modelling, we delineate the governing equations for the aforementioned processes. Grain growth kinetic modelling is briefly reviewed and pertinent data on grain growth of high burnup fuel obtained during power ramps in the Third Risoe Fission Gas Release Project are evaluated. Sample computations are performed, which clearly show the connection between fission gas release and gram growth as a function of time at different isotherms. Models are also proposed for the restructuring of uranium dioxide fuel at high burnup, the so-called rim formation, and its effect on fuel porosity build-up, fuel thermal conductivity and fission gas release. These models are assessed by use of recent experimental data from the High Burnup Rim Project, as well as from post irradiation examinations of high-burnup fuel, irradiated in power reactors. Moreover, models for clad oxide growth and hydrogen pickup in PWRs, applicable to Zircaloy-4, ZIRLO or M5 cladding, are formulated, based on recent in-reactor corrosion data for high-burnup fuel rods. Our evaluation of these data indicates that the oxidation rate of ZIRLO-type materials is about 20% lower than for standard Zircaloy-4 cladding under typical PWR conditions. Likewise, the oxidation rate of M5 seems to be

  7. Dynamic Model of High Temperature PEM Fuel Cell Stack Temperature

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2007-01-01

    cathode air cooled 30 cell HTPEM fuel cell stack developed at the Institute of Energy Technology at Aalborg University. This fuel cell stack uses PEMEAS Celtec P-1000 membranes, runs on pure hydrogen in a dead end anode configuration with a purge valve. The cooling of the stack is managed by running...... conduction through stack insulation, cathode air convection and heating of the inlet gasses in manifold. Various measurements are presented to validate the model predictions of the stack temperatures....

  8. Modeling the mechanical behaviour of CANDU fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Holt, R.A. [Queen' s Univ., Dept. of Mechanical Engineering, Kingston, Ontario (Canada)

    2003-07-01

    Models for the mechanical behaviour of fuel cladding were developed in the period 1973-1983 by staff at AECL CRNL. The models for the mechanical properties of fuel cladding during normal operation were a by-product of programs during the period 1970-1975 to understand the origin of fuel-cladding defects caused by power ramps at Douglas Point and Pickering A. Models for accident conditions were, initially, based heavily on mechanical properties data generated by McGill University and Westinghouse Canada under contract to AECL in the late 1960's and early 1970's and attempts to interpret the data in terms of the underlying deformation mechanisms. The model for normal operating conditions was embodied in the ELESTRES/ELESIM series of codes, and the models for accident conditions were embodied in NIRVANA. (author)

  9. Study of fuel control strategy based on an fuel behavior model for starting conditions; Nenryo kyodo model ni motozuita shidoji no nenryo hosei hosho ni tsuite no kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Y.; Uchida, M.; Iwano, H.; Oba, H. [Nissan Motor Co. Ltd., Tokyo (Japan)

    1997-10-01

    We have applied a fuel behavior model to a fuel injection system which we call SOFIS (Sophisticated and Optimized Fuel Injection System) so that we get air/fuel ratio control accuracy and good driveability. However the fuel behavior under starting conditions is still not clear. To meet low emission rules and to get better driveability under starting conditions, better air/fuel ratio control is necessary. Now we have understood the ignition timing, injection timing, and injection pulse width required in such conditions. In former days, we analyzed the state of the air/fuel mixture under cold conditions and made a new fuel behavior model which considered fuel loss such as hydrocarbons and dissolution into oil and so on. Al this time, we have applied this idea to starting. We confirm this new model offers improved air/fuel ratio control. 6 refs., 9 figs., 3 tabs.

  10. New hybrid model of proton exchange membrane fuel cell

    Institute of Scientific and Technical Information of China (English)

    WANG Rui-min; CAO Guang-yi; ZHU Xin-jian

    2007-01-01

    Model and simulation are good tools for design optimization of fuel cell systems. This paper proposes a new hybrid model of proton exchange membrane fuel cell (PEMFC). The hybrid model includes physical component and black-box component. The physical component represents the well-known part of PEMFC, while artificial neural network (ANN) component estimates the poorly known part of PEMFC. The ANN model can compensate the performance of the physical model. This hybrid model is implemented on Matlab/Simulink software. The hybrid model shows better accuracy than that of the physical model and ANN model. Simulation results suggest that the hybrid model can be used as a suitable and accurate model for PEMFC.

  11. Alternative Liquid Fuels Simulation Model (AltSim).

    Energy Technology Data Exchange (ETDEWEB)

    Baker, Arnold Barry; Williams, Ryan (Hobart and William Smith Colleges, Geneva, NY); Drennen, Thomas E.; Klotz, Richard (Hobart and William Smith Colleges, Geneva, NY)

    2007-10-01

    The Alternative Liquid Fuels Simulation Model (AltSim) is a high-level dynamic simulation model which calculates and compares the production costs, carbon dioxide emissions, and energy balances of several alternative liquid transportation fuels. These fuels include: corn ethanol, cellulosic ethanol, biodiesel, and diesels derived from natural gas (gas to liquid, or GTL) and coal (coal to liquid, or CTL). AltSim allows for comprehensive sensitivity analyses on capital costs, operation and maintenance costs, renewable and fossil fuel feedstock costs, feedstock conversion efficiency, financial assumptions, tax credits, CO{sub 2} taxes, and plant capacity factor. This paper summarizes the preliminary results from the model. For the base cases, CTL and cellulosic ethanol are the least cost fuel options, at $1.60 and $1.71 per gallon, respectively. Base case assumptions do not include tax or other credits. This compares to a $2.35/gallon production cost of gasoline at September, 2007 crude oil prices ($80.57/barrel). On an energy content basis, the CTL is the low cost alternative, at $12.90/MMBtu, compared to $22.47/MMBtu for cellulosic ethanol. In terms of carbon dioxide emissions, a typical vehicle fueled with cellulosic ethanol will release 0.48 tons CO{sub 2} per year, compared to 13.23 tons per year for coal to liquid.

  12. Review of Phenomenological Models for the Initial Phase HCDA Analysis in a Metal-Fueled Sodium-Cooled Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Young Min; Lee, Ki Rim; Ha, Kwi Seok; Chang, Won Pyo; Suk, Soo Dong

    2009-03-15

    The safety aspects of the KALIMER design results from the advanced safety performance characteristics of its ternary alloy metallic fuel. The superior thermal, mechanical, and neutronic performance of the metal-fueled core assures inherent safety response to unprotected and multiple fault accidents which are HCDA initiating events. HCDA has received great attentions because of its significant consequence, leading to substantial core disruption, although its probability of occurrence is very low. The SAS4A code provides an integrated quantitative framework for examining the phenomenological behaviors under HCDA conditions. Various phenomenological models such as prefailure characterization, transient pin response, margins to cladding failure, axial in-pin fuel relocation prior to cladding breach, and molten fuel relocation after cladding breach are required for the HCDA analysis. The important mechanisms which introduce negative reactivity during HCDA are fuel extrusion and in-pin fuel relocation, and structural feedback through thermal-mechanical neutronic effects. This report describes the safety performance characteristics of the metal fuel as observed in ex-pile and in-pile tests, and describes associated theoretical models employed into the SAS4A HCDA analysis code. Most of such tests and experiments, and development of theoretical models have been performed for the IFR program by ANL. This report provides a phenomenological basis for gaining an understanding of the metal fuel performance characteristics that obtained from expile experiments and in-pile tests. This report will provide insight and direction for planning HCDA experiments and developing theoretical models in Korea later.

  13. Electromagnetic modeling for gap measurement between nuclear fuel channel and liquid injection nozzle

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D. H.; Heo, H.; Jeong, H. G. [KAERI, Taejon (Korea, Republic of)

    2003-10-01

    Fuel channels including Pressure Tube(PT) and Calandria Tube(CT) are important components of Pressurized Heavy Water Reactor(PHWR). A sagging for fuel channel increases by heat and radiation exposure with the increasing operating time. The possibility of contact to Liquid Injection Nozzle(LIN) is thus a critical issue in power plant safety. In order to solve this safety issue, electromagnetic technique was applied to compliment the ultrasonic technology. Electromagnetic fields were investigated for the gap measurement between CT and LIN using computer modeling. We calculated the electromagnetic fields, such as, magnetic flux density, current density near the fuel channel and simulated an impedance and a phase angle in receiving coil for obtaining the optimal inspection parameters, such as, frequency, inter-coil spacing, coil size and configuration. This paper shows that the simulated eddy current signals in variance with the CT/LIN gap can be used for baseline data of experimental electromagnetic technique.

  14. Software Platform Evaluation - Verifiable Fuel Cycle Simulation (VISION) Model

    Energy Technology Data Exchange (ETDEWEB)

    J. J. Jacobson; D. E. Shropshire; W. B. West

    2005-11-01

    The purpose of this Software Platform Evaluation (SPE) is to document the top-level evaluation of potential software platforms on which to construct a simulation model that satisfies the requirements for a Verifiable Fuel Cycle Simulation Model (VISION) of the Advanced Fuel Cycle (AFC). See the Software Requirements Specification for Verifiable Fuel Cycle Simulation (VISION) Model (INEEL/EXT-05-02643, Rev. 0) for a discussion of the objective and scope of the VISION model. VISION is intended to serve as a broad systems analysis and study tool applicable to work conducted as part of the AFCI (including costs estimates) and Generation IV reactor development studies. This document will serve as a guide for selecting the most appropriate software platform for VISION. This is a “living document” that will be modified over the course of the execution of this work.

  15. Modelling of fuel spray and combustion in diesel engines

    Energy Technology Data Exchange (ETDEWEB)

    Huttunen, M.T.; Kaario, O.T. [VTT Energy, Espoo (Finland)

    1997-12-31

    Fuel spray and air motion characteristics and combustion in direct injection (DI) diesel engines was studied using computational models of the commercial CFD-code FIRE. Physical subprocesses modelled included Lagrangian spray droplet movement and behaviour (atomisation, evaporation and interaction of spray droplets) and combustion of evaporated liquid spray in the gas phase. Fuel vapour combustion rate was described by the model of Magnussen and Hjertager. The standard k,{epsilon}-model was used for turbulence. In order to be able to predict combustion accurately, the fuel spray penetration should be predicted with reasonable accuracy. In this study, the standard drag coefficient had to be reduced in order to match the computed penetration to the measured one. In addition, the constants in the submodel describing droplet breakup also needed to be adjusted for closer agreement with the measurements. The characteristic time scale of fuel consumption rate k/C{sub R} {epsilon} strongly influenced the heat release and in-cylinder pressure. With a value around 2.0 to 5.0 for C{sub R}, the computed in-cylinder pressure during the compression stroke agreed quite well with the measurements. On the other hand, the in-cylinder pressure was underpredicted during the expansion stroke. This is partly due to the fact that hydrocarbon fuel combustion was modelled as a one-step reaction reading to CO{sub 2} and H{sub 2}O and inadequate description of the mixing of reactants and combustion products. (author) 16 refs.

  16. Mathematical and Computational Modeling of Polymer Exchange Membrane Fuel Cells

    Science.gov (United States)

    Ulusoy, Sehribani

    In this thesis a comprehensive review of fuel cell modeling has been given and based on the review, a general mathematical fuel cell model has been developed in order to understand the physical phenomena governing the fuel cell behavior and in order to contribute to the efforts investigating the optimum performance at different operating conditions as well as with different physical parameters. The steady state, isothermal model presented here accounts for the combined effects of mass and species transfer, momentum conservation, electrical current distribution through the gas channels, the electrodes and the membrane, and the electrochemical kinetics of the reactions in the anode and cathode catalyst layers. One of the important features of the model is that it proposes a simpler modified pseudo-homogeneous/agglomerate catalyst layer model which takes the advantage of the simplicity of pseudo-homogenous modeling while taking into account the effects of the agglomerates in the catalyst layer by using experimental geometric parameters published. The computation of the general mathematical model can be accomplished in 3D, 2D and 1D with the proper assumptions. Mainly, there are two computational domains considered in this thesis. The first modeling domain is a 2D Membrane Electrode Assembly (MEA) model including the modified agglomerate/pseudo-homogeneous catalyst layer modeling with consistent treatment of water transport in the MEA while the second domain presents a 3D model with different flow filed designs: straight, stepped and tapered. COMSOL Multiphysics along with Batteries and Fuel Cell Module have been used for 2D & 3D model computations while ANSYS FLUENT PEMFC Module has been used for only 3D two-phase computation. Both models have been validated with experimental data. With 2D MEA model, the effects of temperature and water content of the membrane as well as the equivalent weight of the membrane on the performance have been addressed. 3D COMSOL simulation

  17. Solar optical codes evaluation for modeling and analyzing complex solar receiver geometries

    Science.gov (United States)

    Yellowhair, Julius; Ortega, Jesus D.; Christian, Joshua M.; Ho, Clifford K.

    2014-09-01

    Solar optical modeling tools are valuable for modeling and predicting the performance of solar technology systems. Four optical modeling tools were evaluated using the National Solar Thermal Test Facility heliostat field combined with flat plate receiver geometry as a benchmark. The four optical modeling tools evaluated were DELSOL, HELIOS, SolTrace, and Tonatiuh. All are available for free from their respective developers. DELSOL and HELIOS both use a convolution of the sunshape and optical errors for rapid calculation of the incident irradiance profiles on the receiver surfaces. SolTrace and Tonatiuh use ray-tracing methods to intersect the reflected solar rays with the receiver surfaces and construct irradiance profiles. We found the ray-tracing tools, although slower in computation speed, to be more flexible for modeling complex receiver geometries, whereas DELSOL and HELIOS were limited to standard receiver geometries such as flat plate, cylinder, and cavity receivers. We also list the strengths and deficiencies of the tools to show tool preference depending on the modeling and design needs. We provide an example of using SolTrace for modeling nonconventional receiver geometries. The goal is to transfer the irradiance profiles on the receiver surfaces calculated in an optical code to a computational fluid dynamics code such as ANSYS Fluent. This approach eliminates the need for using discrete ordinance or discrete radiation transfer models, which are computationally intensive, within the CFD code. The irradiance profiles on the receiver surfaces then allows for thermal and fluid analysis on the receiver.

  18. Advanced Nuclear Fuel Cycle Transitions: Optimization, Modeling Choices, and Disruptions

    Science.gov (United States)

    Carlsen, Robert W.

    Many nuclear fuel cycle simulators have evolved over time to help understan the nuclear industry/ecosystem at a macroscopic level. Cyclus is one of th first fuel cycle simulators to accommodate larger-scale analysis with it liberal open-source licensing and first-class Linux support. Cyclus also ha features that uniquely enable investigating the effects of modeling choices o fuel cycle simulators and scenarios. This work is divided into thre experiments focusing on optimization, effects of modeling choices, and fue cycle uncertainty. Effective optimization techniques are developed for automatically determinin desirable facility deployment schedules with Cyclus. A novel method fo mapping optimization variables to deployment schedules is developed. Thi allows relationships between reactor types and scenario constraints to b represented implicitly in the variable definitions enabling the usage o optimizers lacking constraint support. It also prevents wasting computationa resources evaluating infeasible deployment schedules. Deployed power capacit over time and deployment of non-reactor facilities are also included a optimization variables There are many fuel cycle simulators built with different combinations o modeling choices. Comparing results between them is often difficult. Cyclus flexibility allows comparing effects of many such modeling choices. Reacto refueling cycle synchronization and inter-facility competition among othe effects are compared in four cases each using combinations of fleet of individually modeled reactors with 1-month or 3-month time steps. There are noticeable differences in results for the different cases. The larges differences occur during periods of constrained reactor fuel availability This and similar work can help improve the quality of fuel cycle analysi generally There is significant uncertainty associated deploying new nuclear technologie such as time-frames for technology availability and the cost of buildin advanced reactors

  19. Modelling of Transmitter & Receiver for VSAT Communication System

    Directory of Open Access Journals (Sweden)

    Sanjida Sharmin Mohona

    2015-02-01

    Full Text Available The Satellite communication is an essential part of telecommunication systems which carrying large amount of data (internet, e-mail and telephone traffic in addition to TV signals. Very small aperture terminal (VSAT is widely used for these purposes. This paper aims to provide the framework of VSAT technology in the evolving context of satellite communications in terms of network configuration, services, economics and operational aspects. This paper presents the modelling and simulation aspects of communication blocks of VSAT which can be used in different types of network topology and also includes the numerical results simulated by MATLAB.

  20. Fuel dispersal modeling for aircraft-runway impact scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Tieszen, S.R.

    1995-11-01

    A fuel dispersal model for C-141 transport accidents was developed for the Defense Nuclear Agency`s Fuel Fire Technology Base Program to support Weapon System Safety Assessments. The spectrum of accidents resulting from aircraft impact on a runway was divided into three fuel dispersal regimes: low, intermediate, and high-velocity impact. Sufficient data existed in the accident, crash test, and fuel-filled bomb literature to support development of a qualitative framework for dispersal models, but not quantitative models for all regimes. Therefore, a test series at intermediate scale was conducted to generate data on which to base the model for the high-velocity regime. Tests were conducted over an impact velocity range from 12 m/s to 91 m/s and angles of impact from 22.5{degrees} to 67.5{degrees}. Dependent variables were area covered by dispersed fuel, amount of mass in that area, and location of the area relative to the impact line. Test results showed that no liquid pooling occurred for impact velocities greater than 61 m/s, independent of the angle of impact. Some pooling did occur at lower velocities, but in no test was the liquid-layer thickness greater than 5.25 mm.

  1. VISION -- A Dynamic Model of the Nuclear Fuel Cycle

    Energy Technology Data Exchange (ETDEWEB)

    J. J. Jacobson; A. M. Yacout; S. J. Piet; D. E. Shropshire; G. E. Matthern

    2006-02-01

    The Advanced Fuel Cycle Initiative’s (AFCI) fundamental objective is to provide technology options that – if implemented – would enable long-term growth of nuclear power while improving sustainability and energy security. The AFCI organization structure consists of four areas; Systems Analysis, Fuels, Separations and Transmutations. The Systems Analysis Working Group is tasked with bridging the program technical areas and providing the models, tools, and analyses required to assess the feasibility of design and deploy¬ment options and inform key decision makers. An integral part of the Systems Analysis tool set is the development of a system level model that can be used to examine the implications of the different mixes of reactors, implications of fuel reprocessing, impact of deployment technologies, as well as potential “exit” or “off ramp” approaches to phase out technologies, waste management issues and long-term repository needs. The Verifiable Fuel Cycle Simulation Model (VISION) is a computer-based simulation model that allows performing dynamic simulations of fuel cycles to quantify infrastructure requirements and identify key trade-offs between alternatives. VISION is intended to serve as a broad systems analysis and study tool applicable to work conducted as part of the AFCI (including costs estimates) and Generation IV reactor development studies.

  2. 3-Dimensional Computational Fluid Dynamics Modeling of Solid Oxide Fuel Cell Using Different Fuels

    Science.gov (United States)

    2011-01-01

    fuel cell ( SOFC ) technology has been of great interest over many years due to its...All Rights Reserved iii ABSTRACT Solid oxide fuel cell ( SOFC ) technology has been of great interest over many years due to its... Fuel Cell (PAFC) Molten Carbonate Fuel Cell (MCFC) Solid Oxide Fuel Cell ( SOFC ) This classification in fuel cells broadly depends on the type

  3. Heat Transfer Modeling of Dry Spent Nuclear Fuel Storage Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Lee, S.Y.

    1999-01-13

    The present work was undertaken to provide heat transfer model that accurately predicts the thermal performance of dry spent nuclear fuel storage facilities. One of the storage configurations being considered for DOE Aluminum-clad Spent Nuclear Fuel (Al-SNF), such as the Material and Testing Reactor (MTR) fuel, is in a dry storage facility. To support design studies of storage options a computational and experimental program has been conducted at the Savannah River Site (SRS). The main objective is to develop heat transfer models including natural convection effects internal to an interim dry storage canister and to geological codisposal Waste Package (WP). Calculated temperatures will be used to demonstrate engineering viability of a dry storage option in enclosed interim storage and geological repository WP and to assess the chemical and physical behaviors of the Al-SNF in the dry storage facilities. The current paper describes the modeling approaches and presents the computational results along with the experimental data.

  4. TAFV Alternative Fuels and Vehicles Choice Model Documentation

    Energy Technology Data Exchange (ETDEWEB)

    Greene, D.L.

    2001-07-27

    A model for predicting choice of alternative fuel and among alternative vehicle technologies for light-duty motor vehicles is derived. The nested multinomial logit (NML) mathematical framework is used. Calibration of the model is based on information in the existing literature and deduction based on assuming a small number of key parameters, such as the value of time and discount rates. A spreadsheet model has been developed for calibration and preliminary testing of the model.

  5. Prediction of Group Delay Distribution Around Receiving Point Using Modified IRI Model and IGRF Model

    Institute of Scientific and Technical Information of China (English)

    YAN Zhaowen; WANG Gang; LI Weimin; YU Dapeng; Toyobur RAHMAN

    2011-01-01

    The international reference ionosphere (IRI) model is generally accepted standard ionosphere model.It describes the ionosphere environment in quiet state and predicts the ionosphere parameters within a certain precision.In this paper,we have made a breakthrough in the application of the IRI model by modifying the model for regions of China.The main objectives of this modification are to construct the ionosphere parameters foF2 and M (3000) F2 by using the Chinese reference ionosphere (CRI)coefficients,appropriately increase hmE and hmF2 height,reduce the thickness of F layer,validate the parameter by the measured values,and solve the electron concentration distribution with quasi-parabolic segment (QPS).In this paper,3D ray tracing algorithm is constructed based on the modified IRI model and international geomagnetic reference field (IGRF) model.In short-wave propagation,it can be used to predict the electromagnetic parameters of the receiving point,such as the receiving area,maximum useable frequency (MUF) and the distribution of the group delay etc.,which can help to determine the suitability of the communication.As an example,we estimate the group delay distributions around Changchun in the detection from Qingdao to Changchun using the modified IRI model and IGRF model,and provide technical support for the short-wave communication between the two cities.

  6. Ignition of Metal Powders in Combustion Products of Model Fuel

    Science.gov (United States)

    1974-11-13

    y AD/A-001 172 IGNITION OF METAL POWDERS IN COMBUSTION PRODUCTS OF MODEL FUEL A. K. Klyauzov, et al Foreign Technology...S. Air Force UNCLASSIFIED »b. s»ouc » "I»0«T TITLE IGNITION OF METAL POWDERS IN COMBUSTION PRODUCTS OF MODEL FUEL f* OCJCPIPTIVK NOTKI (Typ* o...report mnd Inclumiv «**»••) Translation S »UTMö«I|I ( Firn tSSS», rnlddl* Inltlml, faar .tarna; A. K. Klyauzov, M. M. Arsh, et al 6

  7. Fuel Conditioning Facility Electrorefiner Model Predictions versus Measurements

    Energy Technology Data Exchange (ETDEWEB)

    D Vaden

    2007-10-01

    Electrometallurgical treatment of spent nuclear fuel is performed in the Fuel Conditioning Facility (FCF) at the Idaho National Laboratory (INL) by electrochemically separating uranium from the fission products and structural materials in a vessel called an electrorefiner (ER). To continue processing without waiting for sample analyses to assess process conditions, an ER process model predicts the composition of the ER inventory and effluent streams via multicomponent, multi-phase chemical equilibrium for chemical reactions and a numerical solution to differential equations for electro-chemical transport. The results of the process model were compared to the electrorefiner measured data.

  8. Numerical modeling of the flow in a cryogenic fuel tank

    Science.gov (United States)

    Greer, Donald Steven

    Developing reusable flight weight cryogenic fuel tanks is one of the technological challenges in designing advanced hypersonic aircraft and the next generation of spacecraft. As an aid in the design of these aircraft, a computational fluid dynamics (CFD) model has been developed specifically for the analysis of flow in a cryogenic fuel tank. The model simulates the transient, two dimensional draining of a fuel tank cross section. The interface between the ullage gas and liquid fuel is modeled as a free surface to enable the calculation of slosh wave dynamics. The drain rate of the liquid fuel is specified as a boundary condition to the model. The ullage gas enters the model to replace the volume of drained liquid. The rate of ullage gas entering the model is calculated from boundary conditions of constant pressure and temperature for the ullage gas. The model employs the full set of Navier-Stokes equations with the exception that viscous dissipation is neglected in the energy equation. The method of solution is an explicit finite difference technique in two dimensional generalized coordinates approximated to second order accuracy in both space and time. The stiffness due to the low Mach number is handled by the method of artificial compressibility. Model comparisons are made to experimental data for free convection to a vertical plate and to free convection inside a horizontal cylinder. Slosh wave dynamics are compared to potential flow calculations for waves inside a square tank. Sample calculations are also performed on a rectangular tank and an eight sided polygon tank to demonstrate the capability of the model.

  9. BISON and MARMOT Development for Modeling Fast Reactor Fuel Performance

    Energy Technology Data Exchange (ETDEWEB)

    Gamble, Kyle Allan Lawrence [Idaho National Lab. (INL), Idaho Falls, ID (United States); Williamson, Richard L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schwen, Daniel [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, Yongfeng [Idaho National Lab. (INL), Idaho Falls, ID (United States); Novascone, Stephen Rhead [Idaho National Lab. (INL), Idaho Falls, ID (United States); Medvedev, Pavel G. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-01

    BISON and MARMOT are two codes under development at the Idaho National Laboratory for engineering scale and lower length scale fuel performance modeling. It is desired to add capabilities for fast reactor applications to these codes. The fast reactor fuel types under consideration are metal (U-Pu-Zr) and oxide (MOX). The cladding types of interest include 316SS, D9, and HT9. The purpose of this report is to outline the proposed plans for code development and provide an overview of the models added to the BISON and MARMOT codes for fast reactor fuel behavior. A brief overview of preliminary discussions on the formation of a bilateral agreement between the Idaho National Laboratory and the National Nuclear Laboratory in the United Kingdom is presented.

  10. Fuel Performance Experiments and Modeling: Fission Gas Bubble Nucleation and Growth in Alloy Nuclear Fuels

    Energy Technology Data Exchange (ETDEWEB)

    McDeavitt, Sean [Texas A & M Univ., College Station, TX (United States); Shao, Lin [Texas A & M Univ., College Station, TX (United States); Tsvetkov, Pavel [Texas A & M Univ., College Station, TX (United States); Wirth, Brian [Univ. of Tennessee, Knoxville, TN (United States); Kennedy, Rory [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-04-07

    Advanced fast reactor systems being developed under the DOE's Advanced Fuel Cycle Initiative are designed to destroy TRU isotopes generated in existing and future nuclear energy systems. Over the past 40 years, multiple experiments and demonstrations have been completed using U-Zr, U-Pu-Zr, U-Mo and other metal alloys. As a result, multiple empirical and semi-empirical relationships have been established to develop empirical performance modeling codes. Many mechanistic questions about fission as mobility, bubble coalescience, and gas release have been answered through industrial experience, research, and empirical understanding. The advent of modern computational materials science, however, opens new doors of development such that physics-based multi-scale models may be developed to enable a new generation of predictive fuel performance codes that are not limited by empiricism.

  11. Shortcut model for water-balanced operation in fuel processor fuel cell systems

    NARCIS (Netherlands)

    Biesheuvel, P.M.; Kramer, G.J.

    2004-01-01

    In a fuel processor, a hydrocarbon or oxygenate fuel is catalytically converted into a mixture rich in hydrogen which can be fed to a fuel cell to generate electricity. In these fuel processor fuel cell systems (FPFCs), water is recovered from the exhaust gases and recycled back into the system. We

  12. Transient air cooling thermal modeling of a PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Adzakpa, K.P.; Ramousse, J.; Dube, Y.; Akremi, H.; Agbossou, K. [Hydrogen Research Institute and Departement de genie electrique, Universite du Quebec a Trois-Rivieres, CP 500, Trois-Rivieres (QC) (Canada); Dostie, M.; Poulin, A.; Fournier, M. [LTE-Hydro-Quebec, 600 av. de la Montagne, Shawinigan (QC) (Canada)

    2008-04-15

    Fuel cell utilization for automobile and residential applications is a promising option in order to help reduce environmental concerns such as pollution. However, fuel cell development requires addressing their dynamic behavior to improve their performances and their life cycle. Since the temperature distribution in the cell is known to be an important factor to the fuel cell's efficiency, a cooling device is often added to homogenize the temperature in the cell and to ensure temperature control. A 3D dynamic thermal model of a single fuel cell is presented in this work in order to study the temperature distribution in a fuel cell cooled from the bottom to the top with air. The model is governed by the thermal energy balance, taking into account the inlet gas humidity. The model is developed with the finite difference method and is implemented in the Matlab/Simulink environment. The validation is based on the performances of the ''NEXA'' fuel cell produced by Ballard Power Systems. The efficiency analysis of that air cooling device reveals that the cell temperature is directly linked to the current density and to the gas humidity - varying from 30 C at 5A to 80 C at 35A at low humidity. Moreover, the temperature non-uniformity in the stack is shown to be very high. As a result, temperatures are higher at the top part of the cell than at the bottom part, with a difference of up to a 5 C. Moreover the non-uniformity of the air cooling between the cells of the stack leads to large temperature variations, up to 8 C, from one cell to another. These temperature variations result in large voltage disparities between the cells, which reduce the total electrical power of the entire stack. (author)

  13. Integration of non-fuel coproducts into the GREET model.

    Science.gov (United States)

    Forman, Grant S; Unnasch, Stefan

    2015-04-07

    The life-cycle greenhouse gas (GHG) emissions of alternative fuels that are capable of replacing conventional, petroleum-derived gasoline and diesel continue to be scrutinized for policy implementation. These alternative fuel technologies can also produce a number of value-adding nonfuel coproducts that require thorough and rigorous assessment in order to achieve an accurate life-cycle GHG emissions value. By using the gas to liquids (GTL) diesel pathway as a proxy for other alternative fuel pathways with coproducts, this paper examines how integration of coproduct analysis using the substitution method is possible within the existing framework and functionality of the GREET model. Using this approach, a GREET-compatible external tool was developed to calculate the life-cycle inventory of GTL coproducts to determine the life-cycle GHG emissions of GTL diesel using the substitution method. In addition to having built-in regional scenarios, this tool allows the user the flexibility to configure a given GTL product slate and to calculate the life-cycle GHG emissions of GTL diesel based on a given product composition. Using this protocol, the life-cycle GHG emissions of GTL diesel can range from 71.7 to 95.7 gCO2e/MJ on a well to wheel basis, with the range in carbon intensity being dependent on the mix of coproducts. These results highlight a weakly understood relationship between fuel and chemical products in LCA models. The coproduct integration approach described herein could potentially be incorporated into fuel LCA models, such as GREET, to allow users to further understand the potential environmental benefits of alternative fuel pathways, such as GTL.

  14. Fuel Burning Rate Model for Stratified Charge Engine

    Institute of Scientific and Technical Information of China (English)

    SONG Jin'ou; JIANG Zejun; YAO Chunde; WANG Hongfu

    2006-01-01

    A zero-dimensional single-zone double-curve model is presented to predict fuel burning rate in stratified charge engines, and it is integrated with GT-Power to predict the overall performance of the stratified charge engines.The model consists of two exponential functions for calculating the fuel burning rate in different charge zones.The model factors are determined by a non-linear curve fitting technique, based on the experimental data obtained from 30 cases in middle and low loads.The results show good agreement between the measured and calculated cylinder pressures,and the deviation between calculated and measured cylinder pressures is less than 5%.The zerodimensional single-zone double-curve model is successful in the combustion modeling for stratified charge engines.

  15. Modeling and cold start in alcohol-fueled engines

    Energy Technology Data Exchange (ETDEWEB)

    Markel, A.J.; Bailey, B.K.

    1998-05-01

    Neat alcohol fuels offer several benefits over conventional gasoline in automotive applications. However, their low vapor pressure and high heat of vaporization make it difficult to produce a flammable vapor composition from a neat alcohol fuel during a start under cold ambient conditions. Various methods have been introduced to compensate for this deficiency. In this study, the authors applied computer modeling and simulation to evaluate the potential of four cold-start technologies for engines fueled by near-neat alcohol. The four technologies were a rich combustor device, a partial oxidation reactor, a catalytic reformer, and an enhanced ignition system. The authors ranked the competing technologies by their ability to meet two primary criteria for cold starting an engine at {minus}25 deg C and also by several secondary parameters related to commercialization. Their analysis results suggest that of the four technologies evaluated, the enhanced ignition system is the best option for further development.

  16. Modeling and cold start in alcohol-fueled engines

    Energy Technology Data Exchange (ETDEWEB)

    Markel, A.J.; Bailey, B.K.

    1998-05-01

    Neat alcohol fuels offer several benefits over conventional gasoline in automotive applications. However, their low vapor pressure and high heat of vaporization make it difficult to produce a flammable vapor composition from a neat alcohol fuel during a start under cold ambient conditions. Various methods have been introduced to compensate for this deficiency. In this study, the authors applied computer modeling and simulation to evaluate the potential of four cold-start technologies for engines fueled by near-neat alcohol. The four technologies were a rich combustor device, a partial oxidation reactor, a catalytic reformer, and an enhanced ignition system. The authors ranked the competing technologies by their ability to meet two primary criteria for cold starting an engine at {minus}25 deg C and also by several secondary parameters related to commercialization. Their analysis results suggest that of the four technologies evaluated, the enhanced ignition system is the best option for further development.

  17. Detailed Chemical Kinetic Modeling of Diesel Combustion with Oxygenated Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Curran, H J; Fisher, E M; Glaude, P-A; Marinov, N M; Pitz, W J; Westbrook, C K; Flynn, P F; Durrett, R P; zur Loye, A O; Akinyemi, O C; Dryer, F L

    2000-01-11

    mixing model to study the premixed, rich ignition process. Using n-heptane as a representative diesel fuel, they showed that addition of an oxygenated additive, methanol, to the fuel reduced the concentrations of a number of hydrocarbon species in the products of the rich ignition. Specifically, methanol addition reduced the total concentrations of acetylene, ethylene and 1,3-butadiene, as well as propargyl and vinyl radicals, in the ignition products. These are the same species shown in a number of studies [4-6] to be responsible for formation of aromatic and polycyclic aromatic species in flames, species which lead eventually to production of soot. Flynn et al. did not, however, examine the kinetic processes responsible for the computed reduction in production of soot precursor species. At least two hypotheses have been advanced to explain the role that oxygenated species play in diesel ignition and the reduction in the concentrations of these species. The first is that the additive, methanol in the case of Flynn et al., does not contain any C-C bonds and cannot then produce significant levels of the species such as acetylene, ethylene or the unsaturated radicals which are known to lead to aromatic species. The second hypothesis is that the product distribution changes very naturally as oxygen is added and the overall equivalence ratio is reduced. In the present study, we repeat the ignition calculations of Flynn et al. and include a number of other oxygenated species to determine which of these theories is more applicable to this model.

  18. Current Capabilities of the Fuel Performance Modeling Code PARFUME

    Energy Technology Data Exchange (ETDEWEB)

    G. K. Miller; D. A. Petti; J. T. Maki; D. L. Knudson

    2004-09-01

    The success of gas reactors depends upon the safety and quality of the coated particle fuel. A fuel performance modeling code (called PARFUME), which simulates the mechanical and physico-chemical behavior of fuel particles during irradiation, is under development at the Idaho National Engineering and Environmental Laboratory. Among current capabilities in the code are: 1) various options for calculating CO production and fission product gas release, 2) a thermal model that calculates a time-dependent temperature profile through a pebble bed sphere or a prismatic block core, as well as through the layers of each analyzed particle, 3) simulation of multi-dimensional particle behavior associated with cracking in the IPyC layer, partial debonding of the IPyC from the SiC, particle asphericity, kernel migration, and thinning of the SiC caused by interaction of fission products with the SiC, 4) two independent methods for determining particle failure probabilities, 5) a model for calculating release-to-birth (R/B) ratios of gaseous fission products, that accounts for particle failures and uranium contamination in the fuel matrix, and 6) the evaluation of an accident condition, where a particle experiences a sudden change in temperature following a period of normal irradiation. This paper presents an overview of the code.

  19. TRISO-Fuel Element Performance Modeling for the Hybrid LIFE Engine with Pu Fuel Blanket

    Energy Technology Data Exchange (ETDEWEB)

    DeMange, P; Marian, J; Caro, M; Caro, A

    2010-02-18

    A TRISO-coated fuel thermo-mechanical performance study is performed for the hybrid LIFE engine to test the viability of TRISO particles to achieve ultra-high burnup of a weapons-grade Pu blanket. Our methodology includes full elastic anisotropy, time and temperature varying material properties for all TRISO layers, and a procedure to remap the elastic solutions in order to achieve fast fluences up to 30 x 10{sup 25} n {center_dot} m{sup -2} (E > 0.18 MeV). In order to model fast fluences in the range of {approx} 7 {approx} 30 x 10{sup 25} n {center_dot} m{sup -2}, for which no data exist, careful scalings and extrapolations of the known TRISO material properties are carried out under a number of potential scenarios. A number of findings can be extracted from our study. First, failure of the internal pyrolytic carbon (PyC) layer occurs within the first two months of operation. Then, the particles behave as BISO-coated particles, with the internal pressure being withstood directly by the SiC layer. Later, after 1.6 years, the remaining PyC crumbles due to void swelling and the fuel particle becomes a single-SiC-layer particle. Unrestrained by the PyC layers, and at the temperatures and fluences in the LIFE engine, the SiC layer maintains reasonably-low tensile stresses until the end-of-life. Second, the PyC creep constant, K, has a striking influence on the fuel performance of TRISO-coated particles, whose stresses scale almost inversely proportional to K. Obtaining more reliable measurements, especially at higher fluences, is an imperative for the fidelity of our models. Finally, varying the geometry of the TRISO-coated fuel particles results in little differences in the scope of fuel performance. The mechanical integrity of 2-cm graphite pebbles that act as fuel matrix has also been studied and it is concluded that they can reliable serve the entire LIFE burnup cycle without failure.

  20. A Markov chain Monte Carlo with Gibbs sampling approach to anisotropic receiver function forward modeling

    Science.gov (United States)

    Wirth, Erin A.; Long, Maureen D.; Moriarty, John C.

    2017-01-01

    Teleseismic receiver functions contain information regarding Earth structure beneath a seismic station. P-to-SV converted phases are often used to characterize crustal and upper-mantle discontinuities and isotropic velocity structures. More recently, P-to-SH converted energy has been used to interrogate the orientation of anisotropy at depth, as well as the geometry of dipping interfaces. Many studies use a trial-and-error forward modeling approach for the interpretation of receiver functions, generating synthetic receiver functions from a user-defined input model of Earth structure and amending this model until it matches major features in the actual data. While often successful, such an approach makes it impossible to explore model space in a systematic and robust manner, which is especially important given that solutions are likely non-unique. Here, we present a Markov chain Monte Carlo algorithm with Gibbs sampling for the interpretation of anisotropic receiver functions. Synthetic examples are used to test the viability of the algorithm, suggesting that it works well for models with a reasonable number of free parameters (<˜20). Additionally, the synthetic tests illustrate that certain parameters are well constrained by receiver function data, while others are subject to severe trade-offs-an important implication for studies that attempt to interpret Earth structure based on receiver function data. Finally, we apply our algorithm to receiver function data from station WCI in the central United States. We find evidence for a change in anisotropic structure at mid-lithospheric depths, consistent with previous work that used a grid search approach to model receiver function data at this station. Forward modeling of receiver functions using model space search algorithms, such as the one presented here, provide a meaningful framework for interrogating Earth structure from receiver function data.

  1. MODELLING AND FUZZY LOGIC CONTROL OF PEM FUEL CELL SYSTEM POWER GENERATION FOR RESIDENTIAL APPLICATION

    OpenAIRE

    Khaled MAMMAR; CHAKER, Abdelkader

    2010-01-01

    This paper presents a dynamic model of Fuel cell system for residential power generation. The models proposedinclude a fuel cell stack model, reformer model and DC/AC inverter model. More then an analytical details ofhow active and reactive power output of a proton-exchange-membrane (PEM) fuel cell system is controlled.Furthermore a fuzzy logic (FLC) controller is used to control active power of PEM fuel cell system. Thecontroller modifies the hydrogen flow feedback from the terminal load. Si...

  2. Molten carbonate fuel cells. Modeling, analysis, simulation, and control

    Energy Technology Data Exchange (ETDEWEB)

    Sundmacher, K.; Kienle, A. [Max-Planck-Institut fuer Dynamik Komplexer Technischer Systeme, Magdeburg (Germany); Pesch, H.J. [Bayreuth Univ. (Germany). Lehrstuhl fuer Ingenieurmathematik; Berndt, J.F. [IPF Beteiligungsgesellschaft Berndt KG, Reilingen (Germany); Huppmann, G. (eds.) [MTU CFC Solutions GmbH, Muenchen (Germany)

    2007-07-01

    This book presents model-based concepts for process analysis and control on a generalized basis. It is structured as follows: Part I - DESIGN AND OPERATION: MTU's Carbonate Fuel Cell HotModule; Operational Experiences. Part II - MODEL-BASED PROCESS ANALYSIS: MCFC Reference Model; Index Analysis of Models; Parameter Identification; Steady State Process Analysis; Hot spot formation and steady state multiplicities; Conceptual design an Reforming concepts. Part III - OPTIMIZATION AND ADVANCED CONTROL: Model reduction and State estimation; Optimal Control Strategies; Optimization of Reforming Catalyst Distribution.

  3. Heavy truck modeling for fuel consumption. Simulations and measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sandberg, T.

    2001-12-01

    Fuel consumption for heavy trucks depends on many factors like roads, weather, and driver behavior that are hard for a manufacturer to influence. However, one design possibility is the power train configuration. Here a new simulation program for heavy trucks is created to find the configuration of the power train that gives the lowest fuel consumption for each transport task. For efficient simulations the model uses production code for speed and gear control, and it uses exchangeable data sets to allow simulation of the whole production range of engine types, on recorded road profiles from all over the world. Combined with a graphical user interface this application is called STARS (Scania Truck And Road Simulation). The forces of rolling resistance and air resistance in the model are validated through an experiment where the propeller shaft torque of a heavy truck is measured. It is found that the coefficient of rolling resistance is strongly dependent on tire temperature, not only on vehicle speed as expected. This led to the development of a new model for rolling resistance. The model includes the dynamic behavior of the tires and relates rolling resistance to tire temperature and vehicle speed. In another experiment the fuel consumption of a test truck in highway driving is measured. The altitude of the road is recorded with a barometer and used in the corresponding simulations. Despite of the limited accuracy of this equipment the simulation program manage to predict a level of fuel consumption only 2% lower than the real measurements. It is concluded that STARS is a good tool for predicting fuel consumption for trucks in highway driving and for comparing different power train configurations.

  4. Heavy truck modeling for fuel consumption. Simulations and measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sandberg, T.

    2001-12-01

    Fuel consumption for heavy trucks depends on many factors like roads, weather, and driver behavior that are hard for a manufacturer to influence. However, one design possibility is the power train configuration. Here a new simulation program for heavy trucks is created to find the configuration of the power train that gives the lowest fuel consumption for each transport task. For efficient simulations the model uses production code for speed and gear control, and it uses exchangeable data sets to allow simulation of the whole production range of engine types, on recorded road profiles from all over the world. Combined with a graphical user interface this application is called STARS (Scania Truck And Road Simulation). The forces of rolling resistance and air resistance in the model are validated through an experiment where the propeller shaft torque of a heavy truck is measured. It is found that the coefficient of rolling resistance is strongly dependent on tire temperature, not only on vehicle speed as expected. This led to the development of a new model for rolling resistance. The model includes the dynamic behavior of the tires and relates rolling resistance to tire temperature and vehicle speed. In another experiment the fuel consumption of a test truck in highway driving is measured. The altitude of the road is recorded with a barometer and used in the corresponding simulations. Despite of the limited accuracy of this equipment the simulation program manage to predict a level of fuel consumption only 2% lower than the real measurements. It is concluded that STARS is a good tool for predicting fuel consumption for trucks in highway driving and for comparing different power train configurations.

  5. Life cycle models of conventional and alternative-fueled automobiles

    Science.gov (United States)

    Maclean, Heather Louise

    This thesis reports life cycle inventories of internal combustion engine automobiles with feasible near term fuel/engine combinations. These combinations include unleaded gasoline, California Phase 2 Reformulated Gasoline, alcohol and gasoline blends (85 percent methanol or ethanol combined with 15 percent gasoline), and compressed natural gas in spark ignition direct and indirect injection engines. Additionally, I consider neat methanol and neat ethanol in spark ignition direct injection engines and diesel fuel in compression ignition direct and indirect injection engines. I investigate the potential of the above options to have a lower environmental impact than conventional gasoline-fueled automobiles, while still retaining comparable pricing and consumer benefits. More broadly, the objective is to assess whether the use of any of the alternative systems will help to lead to the goal of a more sustainable personal transportation system. The principal tool is the Economic Input-Output Life Cycle Analysis model which includes inventories of economic data, environmental discharges, and resource use. I develop a life cycle assessment framework to assemble the array of data generated by the model into three aggregate assessment parameters; economics, externalities, and vehicle attributes. The first step is to develop a set of 'comparable cars' with the alternative fuel/engine combinations, based on characteristics of a conventional 1998 gasoline-fueled Ford Taurus sedan, the baseline vehicle for the analyses. I calculate the assessment parameters assuming that these comparable cars can attain the potential thermal efficiencies estimated by experts for each fuel/engine combination. To a first approximation, there are no significant differences in the assessment parameters for the vehicle manufacture, service, fixed costs, and the end-of-life for any of the options. However, there are differences in the vehicle operation life cycle components and the state of technology

  6. GPS/GLONASS Combined Precise Point Positioning with Receiver Clock Modeling.

    Science.gov (United States)

    Wang, Fuhong; Chen, Xinghan; Guo, Fei

    2015-06-30

    Research has demonstrated that receiver clock modeling can reduce the correlation coefficients among the parameters of receiver clock bias, station height and zenith tropospheric delay. This paper introduces the receiver clock modeling to GPS/GLONASS combined precise point positioning (PPP), aiming to better separate the receiver clock bias and station coordinates and therefore improve positioning accuracy. Firstly, the basic mathematic models including the GPS/GLONASS observation equations, stochastic model, and receiver clock model are briefly introduced. Then datasets from several IGS stations equipped with high-stability atomic clocks are used for kinematic PPP tests. To investigate the performance of PPP, including the positioning accuracy and convergence time, a week of (1-7 January 2014) GPS/GLONASS data retrieved from these IGS stations are processed with different schemes. The results indicate that the positioning accuracy as well as convergence time can benefit from the receiver clock modeling. This is particularly pronounced for the vertical component. Statistic RMSs show that the average improvement of three-dimensional positioning accuracy reaches up to 30%-40%. Sometimes, it even reaches over 60% for specific stations. Compared to the GPS-only PPP, solutions of the GPS/GLONASS combined PPP are much better no matter if the receiver clock offsets are modeled or not, indicating that the positioning accuracy and reliability are significantly improved with the additional GLONASS satellites in the case of insufficient number of GPS satellites or poor geometry conditions. In addition to the receiver clock modeling, the impacts of different inter-system timing bias (ISB) models are investigated. For the case of a sufficient number of satellites with fairly good geometry, the PPP performances are not seriously affected by the ISB model due to the low correlation between the ISB and the other parameters. However, the refinement of ISB model weakens the

  7. A Two-Dimensional PEM Fuel Cell Model

    Science.gov (United States)

    Shi, Zhongying; Wang, Xia; Zhang, Zhuqian

    2006-11-01

    Proton Exchange Membrane (PEM) fuel cell is a typical low temperature cell, where hydrogen and air are fed into the porous anodic electrode and cathodic electrode though the gas distributors on the bipolar plates, respectively. Activated by the catalyst on anode side, hydrogen will spilt into protons and electrons. Since only protons will be allowed to pass through the membrane, electrons must go through an external circuit. Electrons and protons meet air on cathode side to produce water and heat catalyzed by the catalyst on the cathode side. Numerical simulations are useful tools to describe the basic transport and electrochemical phenomena of PEM fuel cells. The goal of the present work is to develop 2-D computational models of PEM fuel cells, which take into account fluid flow, multi- species transport, current distribution and electrical potential. The velocity field in free channel described by Navier-Stokes equation and the velocity field in porous media described by Darcy’s Law are coupled along the channel-MEA interface. The governing differential equations are solved over a single computational domain, which consists of two gas channel layers, two gas diffusion layers, two catalyst layers as well as a membrane. The model is solved with commercial software COMSOL Multiphysics 3.2b. Parametric study will be conducted to analyze the effects of various parameters on the performance of PEM fuel cells. The results, including the mass concentration, the polarization curve and the velocity distribution, will be presented.

  8. Modelling of LOCA Tests with the BISON Fuel Performance Code

    Energy Technology Data Exchange (ETDEWEB)

    Williamson, Richard L [Idaho National Laboratory; Pastore, Giovanni [Idaho National Laboratory; Novascone, Stephen Rhead [Idaho National Laboratory; Spencer, Benjamin Whiting [Idaho National Laboratory; Hales, Jason Dean [Idaho National Laboratory

    2016-05-01

    BISON is a modern finite-element based, multidimensional nuclear fuel performance code that is under development at Idaho National Laboratory (USA). Recent advances of BISON include the extension of the code to the analysis of LWR fuel rod behaviour during loss-of-coolant accidents (LOCAs). In this work, BISON models for the phenomena relevant to LWR cladding behaviour during LOCAs are described, followed by presentation of code results for the simulation of LOCA tests. Analysed experiments include separate effects tests of cladding ballooning and burst, as well as the Halden IFA-650.2 fuel rod test. Two-dimensional modelling of the experiments is performed, and calculations are compared to available experimental data. Comparisons include cladding burst pressure and temperature in separate effects tests, as well as the evolution of fuel rod inner pressure during ballooning and time to cladding burst. Furthermore, BISON three-dimensional simulations of separate effects tests are performed, which demonstrate the capability to reproduce the effect of azimuthal temperature variations in the cladding. The work has been carried out in the frame of the collaboration between Idaho National Laboratory and Halden Reactor Project, and the IAEA Coordinated Research Project FUMAC.

  9. A Comparison of Service Delivery Models for Special Education Middle School Students Receiving Moderate Intervention Services

    Science.gov (United States)

    Jones-Mason, Keely S.

    2012-01-01

    In an effort to improve academic performance for students receiving special education services, a large urban school district in Tennessee has implemented Integrated Service Delivery Model. The purpose of this study was to compare the performance of students receiving instruction in self-contained classrooms to the performance of students…

  10. Induction Heating Model of Cermet Fuel Element Environmental Test (CFEET)

    Science.gov (United States)

    Gomez, Carlos F.; Bradley, D. E.; Cavender, D. P.; Mireles, O. R.; Hickman, R. R.; Trent, D.; Stewart, E.

    2013-01-01

    Deep space missions with large payloads require high specific impulse and relatively high thrust to achieve mission goals in reasonable time frames. Nuclear Thermal Rockets (NTR) are capable of producing a high specific impulse by employing heat produced by a fission reactor to heat and therefore accelerate hydrogen through a rocket nozzle providing thrust. Fuel element temperatures are very high (up to 3000 K) and hydrogen is highly reactive with most materials at high temperatures. Data covering the effects of high-temperature hydrogen exposure on fuel elements are limited. The primary concern is the mechanical failure of fuel elements due to large thermal gradients; therefore, high-melting-point ceramics-metallic matrix composites (cermets) are one of the fuels under consideration as part of the Nuclear Cryogenic Propulsion Stage (NCPS) Advance Exploration System (AES) technology project at the Marshall Space Flight Center. The purpose of testing and analytical modeling is to determine their ability to survive and maintain thermal performance in a prototypical NTR reactor environment of exposure to hydrogen at very high temperatures and obtain data to assess the properties of the non-nuclear support materials. The fission process and the resulting heating performance are well known and do not require that active fissile material to be integrated in this testing. A small-scale test bed; Compact Fuel Element Environmental Tester (CFEET), designed to heat fuel element samples via induction heating and expose samples to hydrogen is being developed at MSFC to assist in optimal material and manufacturing process selection without utilizing fissile material. This paper details the analytical approach to help design and optimize the test bed using COMSOL Multiphysics for predicting thermal gradients induced by electromagnetic heating (Induction heating) and Thermal Desktop for radiation calculations.

  11. Development of standard fuel models in boreal forests of Northeast China through calibration and validation.

    Science.gov (United States)

    Cai, Longyan; He, Hong S; Wu, Zhiwei; Lewis, Benard L; Liang, Yu

    2014-01-01

    Understanding the fire prediction capabilities of fuel models is vital to forest fire management. Various fuel models have been developed in the Great Xing'an Mountains in Northeast China. However, the performances of these fuel models have not been tested for historical occurrences of wildfires. Consequently, the applicability of these models requires further investigation. Thus, this paper aims to develop standard fuel models. Seven vegetation types were combined into three fuel models according to potential fire behaviors which were clustered using Euclidean distance algorithms. Fuel model parameter sensitivity was analyzed by the Morris screening method. Results showed that the fuel model parameters 1-hour time-lag loading, dead heat content, live heat content, 1-hour time-lag SAV(Surface Area-to-Volume), live shrub SAV, and fuel bed depth have high sensitivity. Two main sensitive fuel parameters: 1-hour time-lag loading and fuel bed depth, were determined as adjustment parameters because of their high spatio-temporal variability. The FARSITE model was then used to test the fire prediction capabilities of the combined fuel models (uncalibrated fuel models). FARSITE was shown to yield an unrealistic prediction of the historical fire. However, the calibrated fuel models significantly improved the capabilities of the fuel models to predict the actual fire with an accuracy of 89%. Validation results also showed that the model can estimate the actual fires with an accuracy exceeding 56% by using the calibrated fuel models. Therefore, these fuel models can be efficiently used to calculate fire behaviors, which can be helpful in forest fire management.

  12. Surface science studies of model fuel cell electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Markovic, N.M.; Ross, P.N. [Lawrence Berkeley National Laboratory, Materials Sciences Division, University of California, 94720 Berkeley, CA (United States)

    2002-04-01

    The purpose of this review is to discuss progress in the understanding of electrocatalytic reactions through the study of model systems with surface spectroscopies. Pure metal single crystals and well-characterized bulk alloys have been used quite successfully as models for real (commercial) electrocatalysts. Given the sheer volume of all work in electrocatalysis that is on fuel cell reactions, we will focus on electrocatalysts for fuel cells. Since Pt is the model fuel cell electrocatalyst, we will focus entirely on studies of pure Pt and Pt bimetallic alloys. The electrode reactions discussed include hydrogen oxidation/evolution, oxygen reduction, and the electrooxidation of carbon monoxide, formic acid, and methanol. Surface spectroscopies emphasized are FTIR, STM/AFM and surface X-ray scattering (SXS). The discussion focuses on the relation between the energetics of adsorption of intermediates and the reaction pathway and kinetics, and how the energetics and kinetics relate to the extrinsic properties of the model system, e.g. surface structure and/or composition. Finally, we conclude by discussing the limitations that are reached by using pure metal single crystals and well-characterized bulk alloys as models for real catalysts, and suggest some directions for developing more realistic systems.

  13. Surface science studies of model fuel cell electrocatalysts

    Science.gov (United States)

    Marković, N. M.; Ross, P. N.

    2002-04-01

    The purpose of this review is to discuss progress in the understanding of electrocatalytic reactions through the study of model systems with surface spectroscopies. Pure metal single crystals and well-characterized bulk alloys have been used quite successfully as models for real (commercial) electrocatalysts. Given the sheer volume of all work in electrocatalysis that is on fuel cell reactions, we will focus on electrocatalysts for fuel cells. Since Pt is the model fuel cell electrocatalyst, we will focus entirely on studies of pure Pt and Pt bimetallic alloys. The electrode reactions discussed include hydrogen oxidation/evolution, oxygen reduction, and the electrooxidation of carbon monoxide, formic acid, and methanol. Surface spectroscopies emphasized are FTIR, STM/AFM and surface X-ray scattering (SXS). The discussion focuses on the relation between the energetics of adsorption of intermediates and the reaction pathway and kinetics, and how the energetics and kinetics relate to the extrinsic properties of the model system, e.g. surface structure and/or composition. Finally, we conclude by discussing the limitations that are reached by using pure metal single crystals and well-characterized bulk alloys as models for real catalysts, and suggest some directions for developing more realistic systems.

  14. Transport Studies and Modeling in PEM Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Mittelsteadt, Cortney K. [Giner, Inc., Auburndale, MA (United States); Xu, Hui [Giner, Inc., Auburndale, MA (United States); Brawn, Shelly [Giner, Inc., Auburndale, MA (United States)

    2014-07-30

    This project’s aim was to develop fuel cell components (i.e. membranes, gas-diffusion media (GDM), bipolar plates and flow fields) that possess specific properties (i.e. water transport and conductivity). A computational fluid dynamics model was developed to elucidate the effect of certain parameters on these specific properties. Ultimately, the model will be used to determine sensitivity of fuel cell performance to component properties to determine limiting components and to guide research. We have successfully reached our objectives and achieved most of the milestones of this project. We have designed and synthesized a variety of hydrocarbon block polymer membranes with lower equivalent weight, structure, chemistry, phase separation and process conditions. These membranes provide a broad selection with optimized water transport properties. We have also designed and constructed a variety of devices that are capable of accurately measuring the water transport properties (water uptake, water diffusivity and electro-osmatic drag) of these membranes. These transport properties are correlated to the membranes’ structures derived from X-ray and microscopy techniques to determine the structure-property relationship. We successfully integrated hydrocarbon membrane MEAs with a current distribution board (CBD) to study the impact of hydrocarbon membrane on water transport in fuel cells. We have designed and fabricated various GDM with varying substrate, diffusivity and micro-porous layers (MPL) and characterized their pore structure, tortuosity and hydrophobicity. We have derived a universal chart (MacMullin number as function of wet proofing and porosity) that can be used to characterize various GDM. The abovementioned GDMs have been evaluated in operating fuel cells; their performance is correlated to various pore structure, tortuosity and hydrophobicity of the GDM. Unfortunately, determining a universal relationship between the MacMullin number and these properties

  15. Development of customized fire behavior fuel models for boreal forests of northeastern China.

    Science.gov (United States)

    Wu, Zhi Wei; He, Hong Shi; Chang, Yu; Liu, Zhi Hua; Chen, Hong Wei

    2011-12-01

    Knowledge of forest fuels and their potential fire behavior across a landscape is essential in fire management. Four customized fire behavior fuel models that differed significantly in fuels characteristics and environmental conditions were identified using hierarchical cluster analysis based on fuels data collected across a boreal forest landscape in northeastern China. Fuel model I represented the dense and heavily branched Pinus pumila shrubland which has significant fine live woody fuels. These forests occur mainly at higher mountain elevations. Fuel model II is applicable to forests dominated by Betula platyphylla and Populus davidiana occurring in native forests on hill slopes or at low mountain elevations. This fuel model was differentiated from other fuel models by higher herbaceous cover and lower fine live woody loading. The primary coniferous forests dominated by Larix gmelini and Pinus sylvestris L. var. mongolica were classified as fuel model III and fuel model IV. Those fuel models differed from one another in average cover and height of understory shrub and herbaceous layers as well as in aspect. The potential fire behavior for each fuel model was simulated with the BehavePlus5.0 fire behavior prediction system. The simulation results indicated that the Pinus pumila shrubland fuels had the most severe fire behavior for the 97th percentile weather condition, and had the least severe fire behavior under 90th percentile weather condition. Fuel model II presented the least severe fire potential across weather conditions. Fuel model IV resulted in greater fire severity than Fuel model III across the two weather scenarios that were examined.

  16. Mathematical modeling of diesel fuel hydrotreating

    Science.gov (United States)

    Tataurshikov, A.; Ivanchina, E.; Krivtcova, N.; Krivtsov, E.; Syskina, A.

    2015-11-01

    Hydrotreating of the diesel fraction with the high initial sulfur content of 1,4 mass% is carried out in the flow-through laboratory setup with the industrial GKD-202 catalyst at various process temperature. On the basis of the experimental data the regularities of the hydrogenation reactions are revealed, and the formalized scheme of sulfur-containing components (sulfides, benzothiophenes, and dibenzothiophenes) transformations is made. The mathematical model of hydrotreating process is developed, the constant values for the reaction rate of hydrodesulfurization of the specified components are calculated.

  17. Modeling and control of the output current of a Reformed Methanol Fuel Cell system

    DEFF Research Database (Denmark)

    Justesen, Kristian Kjær; Andreasen, Søren Juhl; Pasupathi, Sivakumar

    2015-01-01

    In this work, a dynamic Matlab SIMULINK model of the relationship between the fuel cell current set point of a Reformed Methanol Fuel Cell system and the output current of the system is developed. The model contains an estimated fuel cell model, based on a polarization curve and assumed first order...

  18. Importance of fossil fuel emission uncertainties over Europe for CO2 modeling: model intercomparison

    NARCIS (Netherlands)

    Peylin, P.; Houweling, S.; Krol, M.C.|info:eu-repo/dai/nl/078760410; Karstens, U.; Pieterse, G.|info:eu-repo/dai/nl/304840858; Ciais, P.; Heimann, M.

    2011-01-01

    Inverse modeling techniques used to quantify surface carbon fluxes commonly assume that the uncertainty of fossil fuel CO2 (FFCO2) emissions is negligible and that intra-annual variations can be neglected. To investigate these assumptions, we analyzed the differences between four fossil fuel

  19. Modelling spent fuel and HLW behaviour in repository conditions

    Energy Technology Data Exchange (ETDEWEB)

    Esparza, A. M.; Esteban, J. A.

    2003-07-01

    The aim of this report is to give the reader an overall insight of the different models, which are used to predict the long-term behaviour of the spent fuels and HLW disposed in a repository. The models must be established on basic data and robust kinetics describing the mechanisms controlling spent fuel alteration/dissolution in a repository. The UO2 matrix, or source term, contains embedded in it the , majority of radionuclides of the spent fuel (some are in the gap cladding). For this reason the SF radionuclides release models play a significant role in the performance assessment of radioactive waste disposal. The differences existing between models published in the literature are due to the conceptual understanding of the processes and the degree of the conservatism used with the parameter values, and the boundary conditions. They mainly differ in their level of simplification and their final objective. Sometimes are focused the show compliance with regulatory requirements, other to support decision making, to increase the level of confidence of public and scientific community, could be empirical, semi-empirical or analytical. The models take into account the experimental results from radionuclides releases and their extrapolation to the very long term. Its necessary a great statistics for have a representative dissolution rate, due at the number of experimental results is not very high and many of them show a great scatter, independently of theirs different compositions by axial and radial variations, due to linear power or local burnup. On the other hand, it is difficult to predict the spent fuel behaviour over the long term, based in short term experiments. In this report is given a little description of the radionuclides distribution in the spent fuel and also in the cladding/pellet gap, grain boundary, cracks and rim zones (the matrix rim zone can be considered with an especial characteristics very different to the rest of the spent fuel), and structural

  20. Mathematical Modeling of a developed Central Receiver Based on Evacuated Solar Tubes

    Directory of Open Access Journals (Sweden)

    Ali Basil. H.

    2016-01-01

    Full Text Available Solar central receiver plays a considerable role in the plant output power; it is one of the most important synthesis in the solar power tower plants. Its performance directly affects the efficiency of the entire solar power generation system. In this study, a new designed receiver model based on evacuated solar tube was proposed, and the dynamic characteristics of the developed receiver were investigated. In order to optimise and evaluate the dynamic characteristics of solar power plant components, the model investigates the solar radiation heat conversion process through the developed receiver, where the energy and mass conservation equations are used to determine the working fluid temperature and state through the receiver parts, beside the calculation and analysis of the thermal losses.

  1. Polymer Electrolyte Membrane (PEM) Fuel Cells Modeling and Optimization

    Science.gov (United States)

    Zhang, Zhuqian; Wang, Xia; Shi, Zhongying; Zhang, Xinxin; Yu, Fan

    2006-11-01

    Performance of polymer electrolyte membrane (PEM) fuel cells is dependent on operating parameters and designing parameters. Operating parameters mainly include temperature, pressure, humidity and the flow rate of the inlet reactants. Designing parameters include reactants distributor patterns and dimensions, electrodes dimensions, and electrodes properties such as porosity, permeability and so on. This work aims to investigate the effects of various designing parameters on the performance of PEM fuel cells, and the optimum values will be determined under a given operating condition.A three-dimensional steady-state electrochemical mathematical model was established where the mass, fluid and thermal transport processes are considered as well as the electrochemical reaction. A Powell multivariable optimization algorithm will be applied to investigate the optimum values of designing parameters. The objective function is defined as the maximum potential of the electrolyte fluid phase at the membrane/cathode interface at a typical value of the cell voltage. The robustness of the optimum design of the fuel cell under different cell potentials will be investigated using a statistical sensitivity analysis. By comparing with the reference case, the results obtained here provide useful tools for a better design of fuel cells.

  2. Development of an Integrated Performance Model for TRISO-Coated Gas Reactor Particle Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Petti, David Andrew; Miller, Gregory Kent; Martin, David George; Maki, John Thomas

    2005-05-01

    The success of gas reactors depends upon the safety and quality of the coated particle fuel. The understanding and evaluation of this fuel requires development of an integrated mechanistic fuel performance model that fully describes the mechanical and physico-chemical behavior of the fuel particle under irradiation. Such a model, called PARFUME (PARticle Fuel ModEl), is being developed at the Idaho National Engineering and Environmental Laboratory. PARFUME is based on multi-dimensional finite element modeling of TRISO-coated gas reactor fuel. The goal is to represent all potential failure mechanisms and to incorporate the statistical nature of the fuel. The model is currently focused on carbide, oxide nd oxycarbide uranium fuel kernels, while the coating layers are the classical IPyC/SiC/OPyC. This paper reviews the current status of the mechanical aspects of the model and presents results of calculations for irradiations from the New Production Modular High Temperature Gas Reactor program.

  3. Statistical modeling and analysis of the influence of antenna polarization error on received power

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The problem of statistical modeling of antenna polarization error is studied and the statistical characteristics of antenna's received power are analyzed. A novel Stokes-vector-based method is presented to describe the conception of antenna's polarization purity. Statistical model of antenna's polarization error in polarization domain is then built up. When an antenna with polarization error of uniform distribution is illuminated by an arbitrary polarized incident field, the probability density of antenna's received power is derived analytically. Finally, a group of curves of deviation and standard deviation of received power are plotted numerically.

  4. Model-based fault diagnosis in PEM fuel cell systems

    Energy Technology Data Exchange (ETDEWEB)

    Escobet, T.; de Lira, S.; Puig, V.; Quevedo, J. [Automatic Control Department (ESAII), Universitat Politecnica de Catalunya (UPC), Rambla Sant Nebridi 10, 08222 Terrassa (Spain); Feroldi, D.; Riera, J.; Serra, M. [Institut de Robotica i Informatica Industrial (IRI), Consejo Superior de Investigaciones Cientificas (CSIC), Universitat Politecnica de Catalunya (UPC) Parc Tecnologic de Barcelona, Edifici U, Carrer Llorens i Artigas, 4-6, Planta 2, 08028 Barcelona (Spain)

    2009-07-01

    In this work, a model-based fault diagnosis methodology for PEM fuel cell systems is presented. The methodology is based on computing residuals, indicators that are obtained comparing measured inputs and outputs with analytical relationships, which are obtained by system modelling. The innovation of this methodology is based on the characterization of the relative residual fault sensitivity. To illustrate the results, a non-linear fuel cell simulator proposed in the literature is used, with modifications, to include a set of fault scenarios proposed in this work. Finally, it is presented the diagnosis results corresponding to these fault scenarios. It is remarkable that with this methodology it is possible to diagnose and isolate all the faults in the proposed set in contrast with other well known methodologies which use the binary signature matrix of analytical residuals and faults. (author)

  5. Experimental Characterization and Modeling of PEM Fuel Cells

    DEFF Research Database (Denmark)

    Jespersen, Jesper Lebæk

    fundamental knowledge of the transport and electrochemical processes of PEM fuel cells and to provide methods for obtaining high quality data for PEM fuel cell simulation model validation. In this thesis three different areas of experimental characterization techniques was investigated, they include: Stack....... In the area of stack flow and pressure distribution, the techniques of CFD, PIV and differential pressure measurements have been adopted to study flow phenomenons in the cathode manifold, with special emphasis on the manifold inlet conguration. It has been shown that these tools are excellent means...... for obtaining very detailed data of the manifold flow. Moreover, the tools complement each other well, as high quality validation data can be obtained from PIV measurements to verify CFD models. AC Impedance Spectroscopy was used to thoroughly characterize a HTPEM single cell. The measurement method...

  6. Testing of a Buran flight-model fuel cell

    Science.gov (United States)

    Schautz, M.; Dudley, G.; Baron, F.; Popov, V.; Pospelov, B.

    A demonstration test program has been performed at European Space Research & Technology Center (ESTEC) on a flight-model Russian 'Photon' fuel cell. The tests, conducted at various power levels up to 23 kW, included current/voltage characteristics, transient behavior, autothermal startup, and impedance measurements. In addition, the product water and the purge gas were analyzed. All test goals were met and no electrochemical limitations were apparent.

  7. Impedance Modeling of Solid Oxide Fuel Cell Cathodes

    DEFF Research Database (Denmark)

    Mortensen, Jakob Egeberg; Søgaard, Martin; Jacobsen, Torben

    2010-01-01

    A 1-dimensional impedance model for a solid oxide fuel cell cathode is formulated and applied to a cathode consisting of 50/50 wt% strontium doped lanthanum cobaltite and gadolinia doped ceria. A total of 42 impedance spectra were recorded in the temperature range: 555-852°C and in the oxygen...... physical parameters such as the cathode thickness. ©2010 COPYRIGHT ECS - The Electrochemical Society...

  8. Modeling and identification of a PEM fuel cell humidification system

    Institute of Scientific and Technical Information of China (English)

    Xianrui DENG; Guoping LIU; George WANG; Min TAN

    2009-01-01

    A theoretical model of a humidifier of proton exchange membrane (PEM) fuel cell systems is developed and analyzed first in this paper. The model shows that there exists a strong nonlinearity in the system. Then, the system is identified using a wavelet networks method. To avoid the curse-of-dimensionality problem, a class of wavelet networks proposed by Billings is employed. The experimental data acquired from the test bench are used for identification. The one-step-ahead predictions and the five-step-ahead predictions are compared with the real measurements, respectively. It shows that the identified model can effectively describe the real system.

  9. A reformer performance model for fuel cell applications

    Science.gov (United States)

    Sandhu, S. S.; Saif, Y. A.; Fellner, J. P.

    A performance model for a reformer, consisting of the catalytic partial oxidation (CPO), high- and low-temperature water-gas shift (HTWGS and LTWGS), and preferential oxidation (PROX) reactors, has been formulated. The model predicts the composition and temperature of the hydrogen-rich reformed fuel-gas mixture needed for the fuel cell applications. The mathematical model equations, based on the principles of classical thermodynamics and chemical kinetics, were implemented into a computer program. The resulting software was employed to calculate the chemical species molar flow rates and the gas mixture stream temperature for the steady-state operation of the reformer. Typical computed results, such as the gas mixture temperature at the CPO reactor exit and the profiles of the fractional conversion of carbon monoxide, temperature, and mole fractions of the chemical species as a function of the catalyst weight in the HTWGS, LTWGS, and PROX reactors, are here presented at the carbon-to-oxygen atom ratio (C/O) of 1 for the feed mixture of n-decane (fuel) and dry air (oxidant).

  10. Thermal modeling of a pressurized air cavity receiver for solar dish Stirling system

    Science.gov (United States)

    Zou, Chongzhe; Zhang, Yanping; Falcoz, Quentin; Neveu, Pierre; Li, Jianlan; Zhang, Cheng

    2017-06-01

    A solar cavity receiver model for the dish collector system is designed in response to growing demand of renewable energy. In the present research field, no investigations into the geometric parameters of a cavity receiver have been performed. The cylindrical receiver in this study is composed of an enclosed bottom at the back, an aperture at the front, a helical pipe inside the cavity and an insulation layer on the external surface of the cavity. The influence of several critical receiver parameters on the thermal efficiency is analyzed in this paper: cavity inner diameter and cavity length. The thermal model in this paper is solved considering the cavity dimensions as variables. Implementing the model into EES, each parameter influence is separately investigated, and a preliminary optimization method is proposed.

  11. Modeling and control of fuel cell based distributed generation systems

    Science.gov (United States)

    Jung, Jin Woo

    This dissertation presents circuit models and control algorithms of fuel cell based distributed generation systems (DGS) for two DGS topologies. In the first topology, each DGS unit utilizes a battery in parallel to the fuel cell in a standalone AC power plant and a grid-interconnection. In the second topology, a Z-source converter, which employs both the L and C passive components and shoot-through zero vectors instead of the conventional DC/DC boost power converter in order to step up the DC-link voltage, is adopted for a standalone AC power supply. In Topology 1, two applications are studied: a standalone power generation (Single DGS Unit and Two DGS Units) and a grid-interconnection. First, dynamic model of the fuel cell is given based on electrochemical process. Second, two full-bridge DC to DC converters are adopted and their controllers are designed: an unidirectional full-bridge DC to DC boost converter for the fuel cell and a bidirectional full-bridge DC to DC buck/boost converter for the battery. Third, for a three-phase DC to AC inverter without or with a Delta/Y transformer, a discrete-time state space circuit model is given and two discrete-time feedback controllers are designed: voltage controller in the outer loop and current controller in the inner loop. And last, for load sharing of two DGS units and power flow control of two DGS units or the DGS connected to the grid, real and reactive power controllers are proposed. Particularly, for the grid-connected DGS application, a synchronization issue between an islanding mode and a paralleling mode to the grid is investigated, and two case studies are performed. To demonstrate the proposed circuit models and control strategies, simulation test-beds using Matlab/Simulink are constructed for each configuration of the fuel cell based DGS with a three-phase AC 120 V (L-N)/60 Hz/50 kVA and various simulation results are presented. In Topology 2, this dissertation presents system modeling, modified space

  12. Enabling Advanced Modeling and Simulations for Fuel-Flexible Combustors

    Energy Technology Data Exchange (ETDEWEB)

    Heinz Pitsch

    2010-05-31

    The overall goal of the present project is to enable advanced modeling and simulations for the design and optimization of fuel-flexible turbine combustors. For this purpose we use a high-fidelity, extensively-tested large-eddy simulation (LES) code and state-of-the-art models for premixed/partially-premixed turbulent combustion developed in the PI's group. In the frame of the present project, these techniques are applied, assessed, and improved for hydrogen enriched premixed and partially premixed gas-turbine combustion. Our innovative approaches include a completely consistent description of flame propagation, a coupled progress variable/level set method to resolve the detailed flame structure, and incorporation of thermal-diffusion (non-unity Lewis number) effects. In addition, we have developed a general flamelet-type transformation holding in the limits of both non-premixed and premixed burning. As a result, a model for partially premixed combustion has been derived. The coupled progress variable/level method and the general flamelet tranformation were validated by LES of a lean-premixed low-swirl burner that has been studied experimentally at Lawrence Berkeley National Laboratory. The model is extended to include the non-unity Lewis number effects, which play a critical role in fuel-flexible combustor with high hydrogen content fuel. More specifically, a two-scalar model for lean hydrogen and hydrogen-enriched combustion is developed and validated against experimental and direct numerical simulation (DNS) data. Results are presented to emphasize the importance of non-unity Lewis number effects in the lean-premixed low-swirl burner of interest in this project. The proposed model gives improved results, which shows that the inclusion of the non-unity Lewis number effects is essential for accurate prediction of the lean-premixed low-swirl flame.

  13. Enabling Advanced Modeling and Simulations for Fuel-Flexible Combustors

    Energy Technology Data Exchange (ETDEWEB)

    Pitsch, Heinz

    2010-05-31

    The overall goal of the present project is to enable advanced modeling and simulations for the design and optimization of fuel-flexible turbine combustors. For this purpose we use a high fidelity, extensively-tested large-eddy simulation (LES) code and state-of-the-art models for premixed/partially-premixed turbulent combustion developed in the PI's group. In the frame of the present project, these techniques are applied, assessed, and improved for hydrogen enriched premixed and partially premixed gas-turbine combustion. Our innovative approaches include a completely consistent description of flame propagation; a coupled progress variable/level set method to resolve the detailed flame structure, and incorporation of thermal-diffusion (non-unity Lewis number) effects. In addition, we have developed a general flamelet-type transformation holding in the limits of both non-premixed and premixed burning. As a result, a model for partially premixed combustion has been derived. The coupled progress variable/level method and the general flamelet transformation were validated by LES of a lean-premixed low-swirl burner that has been studied experimentally at Lawrence Berkeley National Laboratory. The model is extended to include the non-unity Lewis number effects, which play a critical role in fuel-flexible combustor with high hydrogen content fuel. More specifically, a two-scalar model for lean hydrogen and hydrogen-enriched combustion is developed and validated against experimental and direct numerical simulation (DNS) data. Results are presented to emphasize the importance of non-unity Lewis number effects in the lean-premixed low-swirl burner of interest in this project. The proposed model gives improved results, which shows that the inclusion of the non-unity Lewis number effects is essential for accurate prediction of the lean-premixed low-swirl flame.

  14. A review of TRISO-coated particle nuclear fuel performance models

    Institute of Scientific and Technical Information of China (English)

    LIU Bing; LIANG Tongxiang; TANG Chunhe

    2006-01-01

    The success of high temperature gas cooled reactor depends upon the safety and quality of the coated particle fuel. The understanding and evaluation of this fuel requires the development of an integrated mechanistic fuel performance model that fully describes the mechanical and physicochemical behavior of the fuel particle under irradiation. In this paper, a review of the analytical capability of some of the existing computer codes for coated particle fuel was performed. These existing models and codes include FZJ model, JAERI model, Stress3 model, ATLAS model, PARFUME model and TIMCOAT model. The theoretic model, methodology, calculation parameters and benchmark of these codes were classified. Based on the failure mechanism of coated particle, the advantage and limits of the models were compared and discussed. The calculated results of the coated particles for China HTR-10 by using some existing code are shown. Finally, problems and challenges in fuel performance modeling were listed.

  15. A Mathematical Model of a Direct Propane Fuel Cell

    Directory of Open Access Journals (Sweden)

    Hamidreza Khakdaman

    2015-01-01

    Full Text Available A rigorous mathematical model for direct propane fuel cells (DPFCs was developed. Compared to previous models, it provides better values for the current density and the propane concentration at the exit from the anode. This is the first DPFC model to correctly account for proton transport based on the combination of the chemical potential gradient and the electrical potential gradient. The force per unit charge from the chemical potential gradient (concentration gradient that pushes protons from the anode to the cathode is greater than that from the electrical potential gradient that pushes them in the opposite direction. By including the chemical potential gradient, we learn that the proton concentration gradient is really much different than that predicted using the previous models that neglected the chemical potential gradient. Also inclusion of the chemical potential gradient made this model the first one having an overpotential gradient (calculated from the electrical potential gradient with the correct slope. That is important because the overpotential is exponentially related to the reaction rate (current density. The model described here provides a relationship between the conditions inside the fuel cell (proton concentration, overpotential and its performance as measured externally by current density and propane concentration.

  16. System Modeling and Diagnostics for Liquefying-Fuel Hybrid Rockets

    Science.gov (United States)

    Poll, Scott; Iverson, David; Ou, Jeremy; Sanderfer, Dwight; Patterson-Hine, Ann

    2003-01-01

    A Hybrid Combustion Facility (HCF) was recently built at NASA Ames Research Center to study the combustion properties of a new fuel formulation that burns approximately three times faster than conventional hybrid fuels. Researchers at Ames working in the area of Integrated Vehicle Health Management recognized a good opportunity to apply IVHM techniques to a candidate technology for next generation launch systems. Five tools were selected to examine various IVHM techniques for the HCF. Three of the tools, TEAMS (Testability Engineering and Maintenance System), L2 (Livingstone2), and RODON, are model-based reasoning (or diagnostic) systems. Two other tools in this study, ICS (Interval Constraint Simulator) and IMS (Inductive Monitoring System) do not attempt to isolate the cause of the failure but may be used for fault detection. Models of varying scope and completeness were created, both qualitative and quantitative. In each of the models, the structure and behavior of the physical system are captured. In the qualitative models, the temporal aspects of the system behavior and the abstraction of sensor data are handled outside of the model and require the development of additional code. In the quantitative model, less extensive processing code is also necessary. Examples of fault diagnoses are given.

  17. Performance Analysis of Receive Diversity in Wireless Sensor Networks over GBSBE Models

    Directory of Open Access Journals (Sweden)

    Tai-hoon Kim

    2010-12-01

    Full Text Available Wireless sensor networks have attracted a lot of attention recently. In this paper, we develop a channel model based on the elliptical model for multipath components involving randomly placed scatterers in the scattering region with sensors deployed on a field. We verify that in a sensor network, the use of receive diversity techniques improves the performance of the system. Extensive performance analysis of the system is carried out for both single and multiple antennas with the applied receive diversity techniques. Performance analyses based on variations in receiver height, maximum multipath delay and transmit power have been performed considering different numbers of antenna elements present in the receiver array, Our results show that increasing the number of antenna elements for a wireless sensor network does indeed improve the BER rates that can be obtained.

  18. Models and simulations of nuclear fuel materials properties

    Energy Technology Data Exchange (ETDEWEB)

    Stan, M. [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States)], E-mail: mastan@lanl.gov; Ramirez, J.C. [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States); Cristea, P. [University of Bucharest, Faculty of Physics, Bucuresti-Magurele (Romania); Hu, S.Y.; Deo, C.; Uberuaga, B.P.; Srivilliputhur, S.; Rudin, S.P.; Wills, J.M. [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States)

    2007-10-11

    To address the complexity of the phenomena that occur in a nuclear fuel element, a multi-scale method was developed. The method incorporates theory-based atomistic and continuum models into finite element simulations to predict heat transport phenomena. By relating micro and nano-scale models to the macroscopic equilibrium and non-equilibrium simulations, the predictive character of the method is improved. The multi-scale approach was applied to calculations of point defect concentration, helium bubbles formation, oxygen diffusivity, and simulations of heat and mass transport in UO{sub 2+x}.

  19. A state-space model for estimating detailed movements and home range from acoustic receiver data

    DEFF Research Database (Denmark)

    Pedersen, Martin Wæver; Weng, Kevin

    2013-01-01

    We present a state-space model for acoustic receiver data to estimate detailed movement and home range of individual fish while accounting for spatial bias. An integral part of the approach is the detection function, which models the probability of logging tag transmissions as a function...... is used to estimate home range and movement of a reef fish in the Pacific Ocean....

  20. On a Pioneering Polymer Electrolyte Fuel Cell Model

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Adam Z.; Meyers, Jeremy P.

    2010-07-07

    "Polymer Electrolyte Fuel Cell Model" is a seminal work that continues to form the basis for modern modeling efforts, especially models concerning the membrane and its behavior at the continuum level. The paper is complete with experimental data, modeling equations, model validation, and optimization scenarios. While the treatment of the underlying phenomena is limited to isothermal, single-phase conditions, and one-dimensional flow, it represents the key interactions within the membrane at the center of the PEFC. It focuses on analyzing the water balance within the cell and clearly demonstrates the complex interactions of water diffusion and electro-osmotic flux. Cell-level and system-level water balance are key to the development of efficient PEFCs going forward, particularly as researchers address the need to simplify humidification and recycle configurations while increasing the operating temperature of the stack to minimize radiator requirements.

  1. Multiscale Modeling and Uncertainty Quantification for Nuclear Fuel Performance

    Energy Technology Data Exchange (ETDEWEB)

    Estep, Donald [Colorado State Univ., Fort Collins, CO (United States); El-Azab, Anter [Florida State Univ., Tallahassee, FL (United States); Pernice, Michael [Idaho National Lab. (INL), Idaho Falls, ID (United States); Peterson, John W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Polyakov, Peter [Univ. of Wyoming, Laramie, WY (United States); Tavener, Simon [Colorado State Univ., Fort Collins, CO (United States); Xiu, Dongbin [Purdue Univ., West Lafayette, IN (United States); Univ. of Utah, Salt Lake City, UT (United States)

    2017-03-23

    In this project, we will address the challenges associated with constructing high fidelity multiscale models of nuclear fuel performance. We (*) propose a novel approach for coupling mesoscale and macroscale models, (*) devise efficient numerical methods for simulating the coupled system, and (*) devise and analyze effective numerical approaches for error and uncertainty quantification for the coupled multiscale system. As an integral part of the project, we will carry out analysis of the effects of upscaling and downscaling, investigate efficient methods for stochastic sensitivity analysis of the individual macroscale and mesoscale models, and carry out a posteriori error analysis for computed results. We will pursue development and implementation of solutions in software used at Idaho National Laboratories on models of interest to the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program.

  2. Far-field dispersal modeling for fuel-air-explosive devices

    Energy Technology Data Exchange (ETDEWEB)

    Glass, M.W.

    1990-05-01

    A computer model for simulating the explosive dispersal of a fuel agent in the far-field regime is described and is applied to a wide variety of initial conditions to judge their effect upon the resulting fuel/air cloud. This work was directed toward modeling the dispersal process associated with Fuel-Air-Explosives devices. The far-field dispersal regime is taken to be that time after the initial burster charge detonation in which the shock forces no longer dominate the flow field and initial canister and fuel mass breakup has occurred. The model was applied to a low vapor pressure fuel, a high vapor pressure fuel and a solid fuel. A strong dependence of the final cloud characteristics upon the initial droplet size distribution was demonstrated. The predicted fuel-air clouds were highly non-uniform in concentration. 18 refs., 86 figs., 4 tabs.

  3. Development of burnup dependent fuel rod model in COBRA-TF

    Science.gov (United States)

    Yilmaz, Mine Ozdemir

    The purpose of this research was to develop a burnup dependent fuel thermal conductivity model within Pennsylvania State University, Reactor Dynamics and Fuel Management Group (RDFMG) version of the subchannel thermal-hydraulics code COBRA-TF (CTF). The model takes into account first, the degradation of fuel thermal conductivity with high burnup; and second, the fuel thermal conductivity dependence on the Gadolinium content for both UO2 and MOX fuel rods. The modified Nuclear Fuel Industries (NFI) model for UO2 fuel rods and Duriez/Modified NFI Model for MOX fuel rods were incorporated into CTF and fuel centerline predictions were compared against Halden experimental test data and FRAPCON-3.4 predictions to validate the burnup dependent fuel thermal conductivity model in CTF. Experimental test cases from Halden reactor fuel rods for UO2 fuel rods at Beginning of Life (BOL), through lifetime without Gd2O3 and through lifetime with Gd 2O3 and a MOX fuel rod were simulated with CTF. Since test fuel rod and FRAPCON-3.4 results were based on single rod measurements, CTF was run for a single fuel rod surrounded with a single channel configuration. Input decks for CTF were developed for one fuel rod located at the center of a subchannel (rod-centered subchannel approach). Fuel centerline temperatures predicted by CTF were compared against the measurements from Halden experimental test data and the predictions from FRAPCON-3.4. After implementing the new fuel thermal conductivity model in CTF and validating the model with experimental data, CTF model was applied to steady state and transient calculations. 4x4 PWR fuel bundle configuration from Purdue MOX benchmark was used to apply the new model for steady state and transient calculations. First, one of each high burnup UO2 and MOX fuel rods from 4x4 matrix were selected to carry out single fuel rod calculations and fuel centerline temperatures predicted by CTF/TORT-TD were compared against CTF /TORT-TD /FRAPTRAN

  4. Two-port network analysis and modeling of a balanced armature receiver.

    Science.gov (United States)

    Kim, Noori; Allen, Jont B

    2013-07-01

    Models for acoustic transducers, such as loudspeakers, mastoid bone-drivers, hearing-aid receivers, etc., are critical elements in many acoustic applications. Acoustic transducers employ two-port models to convert between acoustic and electromagnetic signals. This study analyzes a widely-used commercial hearing-aid receiver ED series, manufactured by Knowles Electronics, Inc. Electromagnetic transducer modeling must consider two key elements: a semi-inductor and a gyrator. The semi-inductor accounts for electromagnetic eddy-currents, the 'skin effect' of a conductor (Vanderkooy, 1989), while the gyrator (McMillan, 1946; Tellegen, 1948) accounts for the anti-reciprocity characteristic [Lenz's law (Hunt, 1954, p. 113)]. Aside from Hunt (1954), no publications we know of have included the gyrator element in their electromagnetic transducer models. The most prevalent method of transducer modeling evokes the mobility method, an ideal transformer instead of a gyrator followed by the dual of the mechanical circuit (Beranek, 1954). The mobility approach greatly complicates the analysis. The present study proposes a novel, simplified and rigorous receiver model. Hunt's two-port parameters, the electrical impedance Ze(s), acoustic impedance Za(s) and electro-acoustic transduction coefficient Ta(s), are calculated using ABCD and impedance matrix methods (Van Valkenburg, 1964). The results from electrical input impedance measurements Zin(s), which vary with given acoustical loads, are used in the calculation (Weece and Allen, 2010). The hearing-aid receiver transducer model is designed based on energy transformation flow [electric→ mechanic→ acoustic]. The model has been verified with electrical input impedance, diaphragm velocity in vacuo, and output pressure measurements. This receiver model is suitable for designing most electromagnetic transducers and it can ultimately improve the design of hearing-aid devices by providing a simplified yet accurate, physically

  5. Safety analysis, 200 Area, Savannah River Plant: Separations area operations. Receiving Basin for Offsite Fuel (Supplement 3)

    Energy Technology Data Exchange (ETDEWEB)

    Allen, P M

    1983-09-01

    Analysis of the Savannah River Plant RBOF and RRF included an evaluation of the reliability of process equipment and controls, administrative controls, and engineered safety features. The evaluation also identified potential scenarios and radiological consequences. Risks were calculated in terms of 50-year population dose commitment per year (man-rem/year) to the onsite and offsite population within an 80 Km radius of RBOF and RRF, and to an individual at the plant boundary. The total 50-year onsite and offsite population radiological risks of operating the RBOF and RRF were estimated to be 1.0 man-rem/year. These risks are significantly less than the population dose of 54,000 man/rem/yr for natural background radiation in a 50-mile radius. The 50-year maximum offsite individual risk from operating the facility was estimated to be 2.1 {times} 10{sup 5} rem/yr. These risks are significantly lower than 93 mrem/yr an individual is expected to receive from natural background radiation in this area. The analysis shows. that the RBOF and RRF can be operated without undue risk to onsite personnel or to the general public.

  6. Assessment of stochastic models for GPS measurements with different types of receivers

    Institute of Scientific and Technical Information of China (English)

    LI BoFeng; SHEN YunZhong; XU PeiLiang

    2008-01-01

    The stochastic model plays an important role in parameter estimation. The optimal estimator in the sense of least squares can only be obtained by using the correct stochastic model and consequently guarantees the precise positioning in GPS applications. In this contribution, the GPS measurements, collected by different types of geodetic dual-frequency receiver pairs on ultra-short baselines with a sampling interval of 1 s, are used to address their stochastic models, which include the variances of all observation types, the relationship between the observation accuracy and its elevation angle, the time correlation, as well as the correlation between observation types. The results show that the commonly used stochastic model with the assumption that all the raw GPS measurements are independent with the same variance does not meet the need for precise positioning and the elevation-dependent weight model cannot work well for different receiver and observation types. The time correlation and cross correlation are significant as well. It is therefore concluded that the stochastic model is much associ-ated with the receiver and observation types and should be specified for the receiver and observation types.

  7. Alternative Liquid Fuels Simulation Model (AltSim).

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Ryan; Baker, Arnold Barry; Drennen, Thomas E.

    2009-12-01

    The Alternative Liquid Fuels Simulation Model (AltSim) is a high-level dynamic simulation model which calculates and compares the production and end use costs, greenhouse gas emissions, and energy balances of several alternative liquid transportation fuels. These fuels include: corn ethanol, cellulosic ethanol from various feedstocks (switchgrass, corn stover, forest residue, and farmed trees), biodiesel, and diesels derived from natural gas (gas to liquid, or GTL), coal (coal to liquid, or CTL), and coal with biomass (CBTL). AltSim allows for comprehensive sensitivity analyses on capital costs, operation and maintenance costs, renewable and fossil fuel feedstock costs, feedstock conversion ratio, financial assumptions, tax credits, CO{sub 2} taxes, and plant capacity factor. This paper summarizes the structure and methodology of AltSim, presents results, and provides a detailed sensitivity analysis. The Energy Independence and Security Act (EISA) of 2007 sets a goal for the increased use of biofuels in the U.S., ultimately reaching 36 billion gallons by 2022. AltSim's base case assumes EPA projected feedstock costs in 2022 (EPA, 2009). For the base case assumptions, AltSim estimates per gallon production costs for the five ethanol feedstocks (corn, switchgrass, corn stover, forest residue, and farmed trees) of $1.86, $2.32, $2.45, $1.52, and $1.91, respectively. The projected production cost of biodiesel is $1.81/gallon. The estimates for CTL without biomass range from $1.36 to $2.22. With biomass, the estimated costs increase, ranging from $2.19 per gallon for the CTL option with 8% biomass to $2.79 per gallon for the CTL option with 30% biomass and carbon capture and sequestration. AltSim compares the greenhouse gas emissions (GHG) associated with both the production and consumption of the various fuels. EISA allows fuels emitting 20% less greenhouse gases (GHG) than conventional gasoline and diesels to qualify as renewable fuels. This allows several of the

  8. Alternative Liquid Fuels Simulation Model (AltSim).

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Ryan; Baker, Arnold Barry; Drennen, Thomas E.

    2009-12-01

    The Alternative Liquid Fuels Simulation Model (AltSim) is a high-level dynamic simulation model which calculates and compares the production and end use costs, greenhouse gas emissions, and energy balances of several alternative liquid transportation fuels. These fuels include: corn ethanol, cellulosic ethanol from various feedstocks (switchgrass, corn stover, forest residue, and farmed trees), biodiesel, and diesels derived from natural gas (gas to liquid, or GTL), coal (coal to liquid, or CTL), and coal with biomass (CBTL). AltSim allows for comprehensive sensitivity analyses on capital costs, operation and maintenance costs, renewable and fossil fuel feedstock costs, feedstock conversion ratio, financial assumptions, tax credits, CO{sub 2} taxes, and plant capacity factor. This paper summarizes the structure and methodology of AltSim, presents results, and provides a detailed sensitivity analysis. The Energy Independence and Security Act (EISA) of 2007 sets a goal for the increased use of biofuels in the U.S., ultimately reaching 36 billion gallons by 2022. AltSim's base case assumes EPA projected feedstock costs in 2022 (EPA, 2009). For the base case assumptions, AltSim estimates per gallon production costs for the five ethanol feedstocks (corn, switchgrass, corn stover, forest residue, and farmed trees) of $1.86, $2.32, $2.45, $1.52, and $1.91, respectively. The projected production cost of biodiesel is $1.81/gallon. The estimates for CTL without biomass range from $1.36 to $2.22. With biomass, the estimated costs increase, ranging from $2.19 per gallon for the CTL option with 8% biomass to $2.79 per gallon for the CTL option with 30% biomass and carbon capture and sequestration. AltSim compares the greenhouse gas emissions (GHG) associated with both the production and consumption of the various fuels. EISA allows fuels emitting 20% less greenhouse gases (GHG) than conventional gasoline and diesels to qualify as renewable fuels. This allows several of the

  9. Physical modeling of spent-nuclear-fuel container

    Directory of Open Access Journals (Sweden)

    Wang Liping

    2012-11-01

    Full Text Available A new physical simulation model was developed to simulate the casting process of the ductile iron heavy section spent-nuclear-fuel container. In this physical simulation model, a heating unit with DR24 Fe-Cr-Al heating wires was used to compensate the heat loss across the non-natural surfaces of the sample, and a precise and reliable casting temperature controlling/monitoring system was employed to ensure the thermal behavior of the simulated casting to be similar to the actual casting. Also, a mould system was designed, in which changeable mould materials can be used for both the outside and inside moulds for different applications. The casting test was carried out with the designed mould and the cooling curves of central and edge points at different isothermal planes of the casting were obtained. Results show that for most isothermal planes, the temperature control system can keep the temperature differences within 6 ℃ between the edge points and the corresponding center points, indicating that this new physical simulation model has high simulation accuracy, and the mould developed can be used for optimization of casting parameters of spent-nuclear-fuel container, such as composition of ductile iron, the pouring temperature, the selection of mould material and design of cooling system. In addition, to maintain the spheroidalization of the ductile iron, the force-chilling should be used for the current physical simulation to ensure the solidification of casting in less than 2 h.

  10. Integrating fire behavior models and geospatial analysis for wildland fire risk assessment and fuel management planning

    Science.gov (United States)

    Alan A. Ager; Nicole M. Vaillant; Mark A. Finney

    2011-01-01

    Wildland fire risk assessment and fuel management planning on federal lands in the US are complex problems that require state-of-the-art fire behavior modeling and intensive geospatial analyses. Fuel management is a particularly complicated process where the benefits and potential impacts of fuel treatments must be demonstrated in the context of land management goals...

  11. Phosphoric acid fuel cell power plant system performance model and computer program

    Science.gov (United States)

    Alkasab, K. A.; Lu, C. Y.

    1984-01-01

    A FORTRAN computer program was developed for analyzing the performance of phosphoric acid fuel cell power plant systems. Energy mass and electrochemical analysis in the reformer, the shaft converters, the heat exchangers, and the fuel cell stack were combined to develop a mathematical model for the power plant for both atmospheric and pressurized conditions, and for several commercial fuels.

  12. Model documentation Renewable Fuels Module of the National Energy Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-01-01

    This report documents the objectives, analaytical approach and design of the National Energy Modeling System (NEMS) Renewable Fuels Module (RFM) as it relates to the production of the 1996 Annual Energy Outlook forecasts. The report catalogues and describes modeling assumptions, computational methodologies, data inputs, and parameter estimation techniques. A number of offline analyses used in lieu of RFM modeling components are also described.

  13. Contrasting two models of academic self-efficacy--domain-specific versus cross-domain--in children receiving and not receiving special instruction in mathematics.

    Science.gov (United States)

    Jungert, Tomas; Hesser, Hugo; Träff, Ulf

    2014-10-01

    In social cognitive theory, self-efficacy is domain-specific. An alternative model, the cross-domain influence model, would predict that self-efficacy beliefs in one domain might influence performance in other domains. Research has also found that children who receive special instruction are not good at estimating their performance. The aim was to test two models of how self-efficacy beliefs influence achievement, and to contrast children receiving special instruction in mathematics with normally-achieving children. The participants were 73 fifth-grade children who receive special instruction and 70 children who do not receive any special instruction. In year four and five, the children's skills in mathematics and reading were assessed by national curriculum tests, and in their fifth year, self-efficacy in mathematics and reading were measured. Structural equation modeling showed that in domains where children do not receive special instruction in mathematics, self-efficacy is a mediating variable between earlier and later achievement in the same domain. Achievement in mathematics was not mediated by self-efficacy in mathematics for children who receive special instruction. For normal achieving children, earlier achievement in the language domain had an influence on later self-efficacy in the mathematics domain, and self-efficacy beliefs in different domains were correlated. Self-efficacy is mostly domain specific, but may play a different role in academic performance depending on whether children receive special instruction. The results of the present study provided some support of the Cross-Domain Influence Model for normal achieving children. © 2014 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

  14. New high burnup fuel models for NRC`s licensing audit code, FRAPCON

    Energy Technology Data Exchange (ETDEWEB)

    Lanning, D.D.; Beyer, C.E.; Painter, C.L. [Pacific Northwest Laboratory, Richland, WA (United States)

    1996-03-01

    Fuel behavior models have recently been updated within the U.S. Nuclear Regulatory Commission steady-state FRAPCON code used for auditing of fuel vendor/utility-codes and analyses. These modeling updates have concentrated on providing a best estimate prediction of steady-state fuel behavior up to the maximum burnup level s of current data (60 to 65 GWd/MTU rod-average). A decade has passed since these models were last updated. Currently, some U.S. utilities and fuel vendors are requesting approval for rod-average burnups greater than 60 GWd/MTU; however, until these recent updates the NRC did not have valid fuel performance models at these higher burnup levels. Pacific Northwest Laboratory (PNL) has reviewed 15 separate effects models within the FRAPCON fuel performance code (References 1 and 2) and identified nine models that needed updating for improved prediction of fuel behavior at high burnup levels. The six separate effects models not updated were the cladding thermal properties, cladding thermal expansion, cladding creepdown, fuel specific heat, fuel thermal expansion and open gap conductance. Comparison of these models to the currently available data indicates that these models still adequately predict the data within data uncertainties. The nine models identified as needing improvement for predicting high-burnup behavior are fission gas release (FGR), fuel thermal conductivity (accounting for both high burnup effects and burnable poison additions), fuel swelling, fuel relocation, radial power distribution, fuel-cladding contact gap conductance, cladding corrosion, cladding mechanical properties and cladding axial growth. Each of the updated models will be described in the following sections and the model predictions will be compared to currently available high burnup data.

  15. Experiments and Modeling of Multi-Component Fuel Behavior in Combustion

    Science.gov (United States)

    1984-05-01

    heteroatom components. Such models will be necessary input to the large computer codes which calculate the characteristics of two phase reacting flows...methane -nd acetylene accompanied by soot formation. The trends are similar for the two fuels except that JP-4 produces more methane than JP-7. Both fuels...fuels vii1 be increasingly important as the sources shift to heavier petroleum , oil shale, tar sands and coal derived fuels. The combustion of such

  16. Modeling and Diagnostic Software for Liquefying-Fuel Rockets

    Science.gov (United States)

    Poll, Scott; Iverson, David; Ou, Jeremy; Sanderfer, Dwight; Patterson-Hine, Ann

    2005-01-01

    A report presents a study of five modeling and diagnostic computer programs considered for use in an integrated vehicle health management (IVHM) system during testing of liquefying-fuel hybrid rocket engines in the Hybrid Combustion Facility (HCF) at NASA Ames Research Center. Three of the programs -- TEAMS, L2, and RODON -- are model-based reasoning (or diagnostic) programs. The other two programs -- ICS and IMS -- do not attempt to isolate the causes of failures but can be used for detecting faults. In the study, qualitative models (in TEAMS and L2) and quantitative models (in RODON) having varying scope and completeness were created. Each of the models captured the structure and behavior of the HCF as a physical system. It was noted that in the cases of the qualitative models, the temporal aspects of the behavior of the HCF and the abstraction of sensor data are handled outside of the models, and it is necessary to develop additional code for this purpose. A need for additional code was also noted in the case of the quantitative model, though the amount of development effort needed was found to be less than that for the qualitative models.

  17. 40 CFR 600.209-08 - Calculation of vehicle-specific 5-cycle fuel economy values for a model type.

    Science.gov (United States)

    2010-07-01

    ...) For alcohol dual fuel automobiles and natural gas dual fuel automobiles, the procedures of paragraphs... from the tests performed using gasoline or diesel test fuel. (ii) If 5-cycle testing was performed on... values for the model type. (5) For alcohol dual fuel automobiles and natural gas dual fuel automobiles...

  18. Using a Behavior Modeling Approach to Teach Students the Art of Providing and Receiving Verbal Feedback

    Science.gov (United States)

    Maritz, Carol A.

    2008-01-01

    Using a behavior modeling approach, this study examined how students' perceived self-efficacy improved as they developed, delivered, and evaluated professional presentations. Using journal entries and a self-efficacy assessment, students' perceived self-efficacy increased as they learned to provide and receive verbal peer feedback, and to stage…

  19. Using a Behavior Modeling Approach to Teach Students the Art of Providing and Receiving Verbal Feedback

    Science.gov (United States)

    Maritz, Carol A.

    2008-01-01

    Using a behavior modeling approach, this study examined how students' perceived self-efficacy improved as they developed, delivered, and evaluated professional presentations. Using journal entries and a self-efficacy assessment, students' perceived self-efficacy increased as they learned to provide and receive verbal peer feedback, and to stage…

  20. Study and modeling of a pressurized air receiver to power a micro gas turbine

    Science.gov (United States)

    Ndiogou, Baye A.; Thiam, Ababacar; Mbow, Cheikh; Stouffs, Pascal; Azilinon, Dorothé

    2016-05-01

    In the present work a solar receiver with reticulated porous ceramic foam bounded by two concentric cylinders, horizontal axis and length L is selected and studied. A receiver pre-sizing study based on the optimization work of Hischier allowed us to find the dimensions and the receiver input variables. We have developed a mathematical model based on the Representative elementary volume to model the flow and heat transfer within the absorber. The numerical solution of equations set was obtained with FLUENT. The power of 75 kW wanted in this study is obtained with a thermal efficiency equal to 87%. The fields of temperature and velocities from the simulation are analyzed and it is clear from this study that the temperature profiles show the excellent ability of the receiver to transfer the heat to the fluid. The influences of the porosity and mass flow on the thermal efficiency are analyzed also. It emerges from this study that the mass flow rate and porosity are very critical parameters on the thermal performance of the receiver.

  1. A Model for Molten Fuel-Coolant Interaction during Melt Slumping in a Nuclear Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sohal, Manohar Singh; Siefken, Larry James

    1999-10-01

    This paper describes a simple fuel melt slumping model to replace the current parametric model in SCDAP/RELAP5. Specifically, a fuel-coolant interaction (FCI) model is developed to analyze the slumping molten fuel, molten fuel breakup, heat transfer to coolant, relocation of the molten droplets, size of a partially solidified particles that settle to the bottom of the lower plenum, and melt-plenum interaction, if any. Considering our objectives, the molten fuel jet breakup model, and fuel droplets Lagrangian model as included in a code TEXAS-V with Eulerian thermal hydraulics for water and steam from SCDAP/RELAP5 were used. The model was assessed with experimental data from MAGICO-2000 tests performed at University of California at Santa Barbara, and FARO Test L-08 performed at Joint Research Center, Ispra, Italy. The comparison was found satisfactory.

  2. The linearity response of the Planck-LFI flight model receivers

    Energy Technology Data Exchange (ETDEWEB)

    Mennella, A; Bersanelli, M [Universita degli Studi di Milano, Dipartimento di Fisica, Via Celoria 16, 20133 Milano (Italy); Villa, F; Terenzi, L; Cuttaia, F; Butler, R C [INAF-IASF Bologna, Via P.Gobetti 101, 40129 Bologna (Italy); Battaglia, P; Franceschet, C; Lapolla, P M [Thales Alenia Space - Italia, S.S. Padana Superiore 290, 20090 Vimodrone, Milano (Italy); D' Arcangelo, O [CNR, Istituto di Fisica del Plasma, Via Roberto Cozzi 53, 20125 Milano (Italy); Artal, E [Departamento de Ingenieria de Comunicaciones, Universidad de Cantabria, Avenida de los Castros s/n. 39005 Santander (Spain); Davis, R; Kettle, D [Jodrell Bank Centre for Astrophysics, University of Manchester, M13 9PL (United Kingdom); Frailis, M; Galeotta, S [INAF - Osservatorio Astronomico di Trieste, Via Tiepolo 11, 34012 Trieste (Italy); Gregorio, A [Universita degli Studi di Trieste, Dipartimenti di fisica Via Valerio 2, 34127 Trieste (Italy); Hughes, N; Jukkala, P; Kilpiae, V-H [DA-Design Oj, Keskuskatu 29, FI-31600 Jokioinen (Finland); Laaninen, M, E-mail: aniello.mennella@fisica.unimi.i [Ylinen Electronics Oy, Teollisuustie 9A, FIN-02700 Kauniainen (Finland)

    2009-12-15

    In this paper we discuss the linearity response of the Planck-LFI receivers, with particular reference to signal compression measured on the 30 and 44 GHz channels. In the article we discuss the various sources of compression and present a model that accurately describes data measured during tests performed with individual radiomeric chains. After discussing test results we present the best parameter set representing the receiver response and discuss the impact of non linearity on in-flight calibration, which is shown to be negligible.

  3. Developing custom fire behavior fuel models from ecologically complex fuel structures for upper Atlantic Coastal Plain forests

    Science.gov (United States)

    Bernard R. Parresol; Joe H. Scott; Anne Andreu; Susan Prichard; Laurie Kurth

    2012-01-01

    Currently geospatial fire behavior analyses are performed with an array of fire behavior modeling systems such as FARSITE, FlamMap, and the Large Fire Simulation System. These systems currently require standard or customized surface fire behavior fuel models as inputs that are often assigned through remote sensing information. The ability to handle hundreds or...

  4. The effective and dust free receiving station and handling for the low calorific value solid fuels; Tehokas ja poelytoen seospolttoaineiden vastaanottoasema sekae kaesittely- ja kuljetinjaerjestelmae

    Energy Technology Data Exchange (ETDEWEB)

    Nojonen, O. [Finntech Oy, Espoo (Finland); Jaervinen, T. [VTT Energy, Jyvaeskylae (Finland). Energy Use

    1995-12-31

    The aim of the project was to get higher automatization level and improve dust preventing in solid fuel receiving stations. There are two general types of receiving stations in the Finnish power plants: large unloading stations for the side tipping devices of trucks and small ones for the rear tipping devices of trucks. In the first ones the trucks empty their load (approx. 100 m{sup 3} loose bulk density) divided by hauling unit and trailer within few (5-10) minutes into a rectangular box, which depth is approx. 3 m. The discharging causes a strong counter current air and dust flow (20-40 m{sup 3}/s) upwards and the dust will easily spread out all over the station. In the second ones the discharging takes place from the rear of truck and trailer using loadspace conveyor of the vehicle within 20 minutes. The material falls on a (belt) conveyor, which is on the floor level. The problems in side tipping system are connected with dust and surplus time, which is needed for the preparation and completion of unloading and sampling. For the fine dust control has also been tested water spray (fog) nozzles and tried to utilise a settling chamber for the dust stream. Also the using the settling chamber equipped with air suction connections and cyclone separation may be effective. In the rear tipping system are also applied bag filters because of smaller air quantities. The rapid truck positioning and control in the receiving station is one of the presupposition for the fast and accurate unloading. This can be done using ultrasonic sensing methods. Also the ensuring of accurate discharging can be based on the modern technology. One of the basic things is the enlarging of video control (CCD -cameras)

  5. Mechanistic Model for Atomization of Superheated Liquid Jet Fuel Project

    Data.gov (United States)

    National Aeronautics and Space Administration — As air-breathing combustion applications advance, increased use of fuel for cooling, combined with cycle advancements, leads to a situation where the fuel can...

  6. Mechanistic Model for Atomization of Superheated Liquid Jet Fuel Project

    Data.gov (United States)

    National Aeronautics and Space Administration — As air-breathing combustion applications advance, increased use of fuel for cooling, combined with cycle advancements, leads to a situation where the fuel can become...

  7. Oxy-fuel combustion of pulverized fuels: Combustion fundamentals and modeling

    DEFF Research Database (Denmark)

    Yin, Chungen; Yan, Jinyue

    2016-01-01

    Oxy-fuel combustion of pulverized fuels (PF), as a promising technology for CO2 capture from power plants, has gained a lot of concerns and also advanced considerable research, development and demonstration in the last past years worldwide. The use of CO2 or the mixture of CO2 and H2O vapor as th...

  8. Multi-Fuel oxidation in Solid Oxide Fuel Cells: Model anodes and system studies

    NARCIS (Netherlands)

    Patel, H.C.

    2015-01-01

    With the evolution of renewable energy technologies it has become necessary that a balance is found between power production with conventional energy sources and other long term solutions. SOFCs offer an alternative for utilising conventional fossil fuels as well as sustainable biomass derived fuels

  9. BELA receiver performance modeling over the BepiColombo mission lifetime

    Science.gov (United States)

    Gunderson, Kurt; Thomas, Nicolas

    2010-01-01

    Performance modeling of the BepiColombo laser altimeter (BELA) receiver has been performed in the context of return pulse detection probability and measurement accuracies. Models have been extended beyond earlier work [Gunderson, K., Thomas, N., Rohner, M., 2006. A laser altimeter performance model and its application to BELA. IEEE Transactions on Geoscience and Remote Sensing 44, 3308-3319] to explore the receiver response to time-varying orbital conditions and potential instrument component degradations over the mission lifetime. New signal processing derivations are presented, and the set of measurement accuracy predictions has been broadened to include albedo and return pulse width in addition to range accuracy. Two detector gain optimization derivations are also described and applied as guides towards the identification of a preferred performance enhancing strategy.

  10. Behavioral modeling and simulation of multi-standard RF receivers using MATLAB/SIMULINK

    Science.gov (United States)

    Morgado, Alonso; del Río, Rocío; de la Rosa, José M.

    2007-05-01

    This paper presents a SIMULINK block set for the behavioral modeling and high-level simulation of RF receiver frontends. The toolbox includes a library with the main RF circuit models that are needed to implement wireless transceivers, namely: low noise amplifiers, mixers, oscillators, filters and programmable gain amplifiers. There is also a library including other blocks like the antenna, duplexer filter and switches, required to implement reconfigurable architectures. Behavioral models of building blocks include the main ideal functionality as well as the following non-idealities: thermal noise characterized by the Noise Figure (NF) and the Signal-to-Noise Ratio (SNR) and nonlinearity expressed by the input-referred 2nd- and 3rd-order intercept points, IIP II and IIP 3, respectively. In addition to these general parameters, some block specific errors have been also included, like oscillator phase noise and mixer offset. These models have been incorporated into the SIMULINK environment making an extensive use of C-coded S-functions and reducing the number of library block elements. This approach reduces the simulation time while keeping high accuracy, what makes the proposed toolbox very appropriate to be combined with an optimizer for the automated high-level synthesis of radio receivers. As an application of the capabilities of the presented toolbox, a multi-standard Direct-Conversion Receiver (DCR) intended for 4G telecom systems is modeled and simulated considering the building-block requirements for the different standards.

  11. Modeling of burnup express-estimation for UO{sub 2}-fuel

    Energy Technology Data Exchange (ETDEWEB)

    Likhanskii, Vladimir V.; Tokarev, Sergey A.; Vilkhivskaya, Olga V., E-mail: vilhivskaya_olga@mail.ru

    2017-03-15

    Highlights: • Proposed engineering model estimates fuel burnup by {sup 134}Cs/{sup 137}Cs activity ratio. • Buildup of cesium isotopes relies on changing neutron spectrum in the core cycle. • {sup 134}Cs/{sup 137}Cs activity ratios in FAs with Gd-doped fuel rods are analyzed. • Comparison of the model calculations with the NPPs spike measurements is presented. - Abstract: The paper presents the developed engineering model of cesium isotopes production as function of UO{sub 2}-fuel burnup and an assessment of their activity ratios. The model considers the evolution of linear power of gadolinium-doped fuel rods and fuel rods surrounding them in fuel assemblies with high enrichment fuel, harder neutron spectrum, and the changes in cross-sections of neutron reactions in thermal and epithermal energy areas. Parametrical dependences in the model are based on the fuel operation data for nuclear power plants and on the detailed neutronic-physical calculations of the core. Presented are the results of the model calculations for the {sup 134}Cs/{sup 137}Cs activity ratios in fuel taking into account the parameter of hardness of the neutron spectrum during the first irradiation cycle for fuel with enrichment ranging from 3.6 wt% in {sup 235}U.

  12. An Integrated Model for Identifying Linkages Between the Management of Fuel Treatments, Fire and Ecosystem Services

    Science.gov (United States)

    Bart, R. R.; Anderson, S.; Moritz, M.; Plantinga, A.; Tague, C.

    2015-12-01

    Vegetation fuel treatments (e.g. thinning, prescribed burning) are a frequent tool for managing fire-prone landscapes. However, predicting how fuel treatments may affect future wildfire risk and associated ecosystem services, such as forest water availability and streamflow, remains a challenge. This challenge is in part due to the large range of conditions under which fuel treatments may be implemented, as response is likely to vary with species type, rates of vegetation regrowth, meteorological conditions and physiographic properties of the treated site. It is also due to insufficient understanding of how social factors such as political pressure, public demands and economic constraints affect fuel management decisions. To examine the feedbacks between ecological and social dimensions of fuel treatments, we present an integrated model that links a biophysical model that simulates vegetation and hydrology (RHESSys), a fire spread model (WMFire) and an empirical fuel treatment model that accounts for agency decision-making. We use this model to investigate how management decisions affect landscape fuel loads, which in turn affect fire severity and ecosystem services, which feedback to management decisions on fuel treatments. We hypothesize that this latter effect will be driven by salience theory, which predicts that fuel treatments are more likely to occur following major wildfire events. The integrated model provides a flexible framework for answering novel questions about fuel treatments that span social and ecological domains, areas that have previously been treated separately.

  13. Wildland fire emissions, carbon, and climate: Modeling fuel consumption

    Science.gov (United States)

    Roger D. Ottmar

    2014-01-01

    Fuel consumption specifies the amount of vegetative biomass consumed during wildland fire. It is a two-stage process of pyrolysis and combustion that occurs simultaneously and at different rates depending on the characteristics and condition of the fuel, weather, topography, and in the case of prescribed fire, ignition rate and pattern. Fuel consumption is the basic...

  14. Modeling of the filling and cooling processes of hot fuel mains in Liquid Fuel Rocket Power Plant (LFRPP)

    Science.gov (United States)

    Prisnyakov, V. F.; Pokrishkin, V. V.; Serebryansky, V. N.

    A mathematical model of heat and mass exchange processes during filling and cooling of hot fuel mains of the Liquid Fuel Rocket Power Plant (LFRPP), which allows to define a mass consumption and distribution of two-phase flow parameters by the length of pipeline. Results of calculations are compared with experimental data, taken during filling of the main with a supply of liquid oxygen from the tank into the combustion chamber. Also, the results of modeling of hydrogen main dynamic characteristics of LFRPP in the same conditions are given.

  15. EIA model documentation: Electricity market module - electricity fuel dispatch

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-01

    This report documents the National Energy Modeling System Electricity Fuel Dispatch Submodule (EFD), a submodule of the Electricity Market Module (EMM) as it was used for EIA`s Annual Energy Outlook 1997. It replaces previous documentation dated March 1994 and subsequent yearly update revisions. The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, model source code, and forecast results generated through the synthesis and scenario development based on these components. This document serves four purposes. First, it is a reference document providing a detailed description of the model for reviewers and potential users of the EFD including energy experts at the Energy Information Administration (EIA), other Federal agencies, state energy agencies, private firms such as utilities and consulting firms, and non-profit groups such as consumer and environmental groups. Second, this report meets the legal requirement of the Energy Information Administration (EIA) to provide adequate documentation in support of its statistical and forecast reports. Third, it facilitates continuity in model development by providing documentation which details model enhancements that were undertaken for AE097 and since the previous documentation. Last, because the major use of the EFD is to develop forecasts, this documentation explains the calculations, major inputs and assumptions which were used to generate the AE097.

  16. Aspect Ratio of Receiver Node Geometry based Indoor WLAN Propagation Model

    Science.gov (United States)

    Naik, Udaykumar; Bapat, Vishram N.

    2016-09-01

    This paper presents validation of indoor wireless local area network (WLAN) propagation model for varying rectangular receiver node geometry. The rectangular client node configuration is a standard node arrangement in computer laboratories of academic institutes and research organizations. The model assists to install network nodes for the better signal coverage. The proposed model is backed by wide ranging real time received signal strength measurements at 2.4 GHz. The shadow fading component of signal propagation under realistic indoor environment is modelled with the dependency on varying aspect ratio of the client node geometry. The developed new model is useful in predicting indoor path loss for IEEE 802.11b/g WLAN. The new model provides better performance in comparison to well known International Telecommunication Union and free space propagation models. It is shown that the proposed model is simple and can be a useful tool for indoor WLAN node deployment planning and quick method for the best utilisation of the office space.

  17. Aspect Ratio of Receiver Node Geometry based Indoor WLAN Propagation Model

    Science.gov (United States)

    Naik, Udaykumar; Bapat, Vishram N.

    2017-08-01

    This paper presents validation of indoor wireless local area network (WLAN) propagation model for varying rectangular receiver node geometry. The rectangular client node configuration is a standard node arrangement in computer laboratories of academic institutes and research organizations. The model assists to install network nodes for the better signal coverage. The proposed model is backed by wide ranging real time received signal strength measurements at 2.4 GHz. The shadow fading component of signal propagation under realistic indoor environment is modelled with the dependency on varying aspect ratio of the client node geometry. The developed new model is useful in predicting indoor path loss for IEEE 802.11b/g WLAN. The new model provides better performance in comparison to well known International Telecommunication Union and free space propagation models. It is shown that the proposed model is simple and can be a useful tool for indoor WLAN node deployment planning and quick method for the best utilisation of the office space.

  18. FRED fuel behaviour code: Main models and analysis of Halden IFA-503.2 tests

    Energy Technology Data Exchange (ETDEWEB)

    Mikityuk, K., E-mail: konstantin.mikityuk@psi.ch [Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Shestopalov, A., E-mail: shest@dhtp.kiae.ru [RRC' Kurchatov Institute' , Kurchatov sq, 123182 Moscow (Russian Federation)

    2011-07-15

    Highlights: > We developed a new fuel rod behaviour code named FRED. > Main models and assumptions are described. > The code was checked using the IFA-503.2 tests performed at the Halden reactor. - Abstract: The FRED fuel rod code is being developed for thermal and mechanical simulation of fast breeder reactor (FBR) and light-water reactor (LWR) fuel behaviour under base-irradiation and accident conditions. The current version of the code calculates temperature distribution in fuel rods, stress-strain condition of cladding, fuel deformation, fuel-cladding gap conductance, and fuel rod inner pressure. The code was previously evaluated in the frame of two OECD mixed plutonium-uranium oxide (MOX) fuel performance benchmarks and then integrated into PSI's FAST code system to provide the fuel rod temperatures necessary for the neutron kinetics and thermal-hydraulic modules in transient calculations. This paper briefly overviews basic models and material property database of the FRED code used to assess the fuel behaviour under steady-state conditions. In addition, the code was used to simulate the IFA-503.2 tests, performed at the Halden reactor for two PWR and twelve VVER fuel samples under base-irradiation conditions. This paper presents the results of this simulation for two cases using a code-to-data comparison of fuel centreline temperatures, internal gas pressures, and fuel elongations. This comparison has demonstrated that the code adequately describes the important physical mechanisms of the uranium oxide (UOX) fuel rod thermal performance under steady-state conditions. Future activity should be concentrated on improving the model and extending the validation range, especially to the MOX fuel steady-state and transient behaviour.

  19. Verify Super Double-Heterogeneous Spherical Lattice Model for Equilibrium Fuel Cycle Analysis AND HTR Spherical Super Lattice Model for Equilibrium Fuel Cycle Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Gray S. Chang

    2005-11-01

    The currently being developed advanced High Temperature gas-cooled Reactors (HTR) is able to achieve a simplification of safety through reliance on innovative features and passive systems. One of the innovative features in these HTRs is reliance on ceramic-coated fuel particles to retain the fission products even under extreme accident conditions. Traditionally, the effect of the random fuel kernel distribution in the fuel pebble / block is addressed through the use of the Dancoff correction factor in the resonance treatment. However, the Dancoff correction factor is a function of burnup and fuel kernel packing factor, which requires that the Dancoff correction factor be updated during Equilibrium Fuel Cycle (EqFC) analysis. An advanced KbK-sph model and whole pebble super lattice model (PSLM), which can address and update the burnup dependent Dancoff effect during the EqFC analysis. The pebble homogeneous lattice model (HLM) is verified by the burnup characteristics with the double-heterogeneous KbK-sph lattice model results. This study summarizes and compares the KbK-sph lattice model and HLM burnup analyzed results. Finally, we discuss the Monte-Carlo coupling with a fuel depletion and buildup code - ORIGEN-2 as a fuel burnup analysis tool and its PSLM calculated results for the HTR EqFC burnup analysis.

  20. Modeling Water Management in Polymer-Electrolyte Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Department of Chemical Engineering, University of California, Berkeley; Weber, Adam; Weber, Adam Z.; Balliet, Ryan; Gunterman, Haluna P.; Newman, John

    2007-09-07

    Fuel cells may become the energy-delivery devices of the 21st century with realization of a carbon-neutral energy economy. Although there are many types of fuel cells, polymerelectrolyte fuel cells (PEFCs) are receiving the most attention for automotive and small stationary applications. In a PEFC, hydrogen and oxygen are combined electrochemically to produce water, electricity, and waste heat. During the operation of a PEFC, many interrelated and complex phenomena occur. These processes include mass and heat transfer, electrochemical reactions, and ionic and electronic transport. Most of these processes occur in the through-plane direction in what we term the PEFC sandwich as shown in Figure 1. This sandwich comprises multiple layers including diffusion media that can be composite structures containing a macroporous gas-diffusion layer (GDL) and microporous layer (MPL), catalyst layers (CLs), flow fields or bipolar plates, and a membrane. During operation fuel is fed into the anode flow field, moves through the diffusion medium, and reacts electrochemically at the anode CL to form hydrogen ions and electrons. The oxidant, usually oxygen in air, is fed into the cathode flow field, moves through the diffusion medium, and is electrochemically reduced at the cathode CL by combination with the generated protons and electrons. The water, either liquid or vapor, produced by the reduction of oxygen at the cathode exits the PEFC through either the cathode or anode flow field. The electrons generated at the anode pass through an external circuit and may be used to perform work before they are consumed at the cathode. The performance of a PEFC is most often reported in the form of a polarization curve, as shown in Figure 2. Roughly speaking, the polarization curve can be broken down into various regions. First, it should be noted that the equilibrium potential differs from the open-circuit voltage due mainly to hydrogen crossover through the membrane (i.e., a mixed potential

  1. Characterization and Modeling of a Methanol Reforming Fuel Cell System

    DEFF Research Database (Denmark)

    Sahlin, Simon Lennart

    topologies is the Reformed Methanol Fuel Cell (RMFC) system that operates on a mix of methanol and water. The fuel is reformed with a steam reforming to a hydrogen rich gas, however with additional formation of Carbon Monoxide and Carbon Dioxide. High Temperature Polymer Electrolyte Membrane Fuel Cell (HT...... to heat up the steam reforming process. However, utilizing the excess hydrogen in the system complicates the RMFC system as the amount of hydrogen can vary depending on the fuel methanol supply, fuel cell load and the reformer gas composition. This PhD study has therefore been involved in investigating......Many fuel cells systems today are operated with compressed hydrogen which has great benefits because of the purity of the hydrogen and the relatively simple storage of the fuel. However, compressed hydrogen is stored in the range of 800 bar, which can be expensive to compress.One of the interesting...

  2. An Equivalent Electrical Circuit Model of Proton Exchange Membrane Fuel Cells Based on Mathematical Modelling

    Directory of Open Access Journals (Sweden)

    Dinh An Nguyen

    2012-07-01

    Full Text Available Many of the Proton Exchange Membrane Fuel Cell (PEMFC models proposed in the literature consist of mathematical equations. However, they are not adequately practical for simulating power systems. The proposed model takes into account phenomena such as activation polarization, ohmic polarization, double layer capacitance and mass transport effects present in a PEM fuel cell. Using electrical analogies and a mathematical modeling of PEMFC, the circuit model is established. To evaluate the effectiveness of the circuit model, its static and dynamic performances under load step changes are simulated and compared to the numerical results obtained by solving the mathematical model. Finally, the applicability of our model is demonstrated by simulating a practical system.

  3. Emissions and Fuel Consumption Modeling for Evaluating Environmental Effectiveness of ITS Strategies

    Directory of Open Access Journals (Sweden)

    Yuan-yuan Song

    2013-01-01

    Full Text Available Road transportation is a major fuel consumer and greenhouse gas emitter. Recently, the intelligent transportation systems (ITSs technologies, which can improve traffic flow and safety, have been developed to reduce the fuel consumption and vehicle emissions. Emission and fuel consumption estimation models play a key role in the evaluation of ITS technologies. Based on the influence analysis of driving parameters on vehicle emissions, this paper establishes a set of mesoscopic vehicle emission and fuel consumption models using the real-world vehicle operation and emission data. The results demonstrate that these models are more appropriate to evaluate the environmental effectiveness of ITS strategies with enough estimation accuracy.

  4. Hydrocarbon Fuel Thermal Performance Modeling based on Systematic Measurement and Comprehensive Chromatographic Analysis

    Science.gov (United States)

    2016-07-27

    Conference Paper 3. DATES COVERED (From - To) 10 June 2016 - 27 July 2016 4. TITLE AND SUBTITLE Hydrocarbon Fuel Thermal Performance Modeling based on...The Johns Hopkins University Energetics Research Group (JHU/ERG), Columbia, MD and University of Washington, Seattle, WA 14. ABSTRACT Ensuring fuel ...is a common requirement for aircraft, rockets, and hypersonic vehicles. The Aerospace Fuels Quality Test and Model Development (AFQTMoDev) project

  5. Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen

    In designing and controlling fuel cell sys-tems it is advantageous having models predicting the behavior of the fuel cells in steady-state as well as in dynamic ope-ration. This work examines the use of electro-chemical impedance spectroscopy (EIS) for characterizing and developing a model for a ...... for a high temperature PEM (HTPEM) fuel cell stack. A Labview virtual interface has been developed to perform the signal generation and acquisition which is needed to perform EIS....

  6. 40 CFR 600.208-08 - Calculation of FTP-based and HFET-based fuel economy values for a model type.

    Science.gov (United States)

    2010-07-01

    ... calculate the fuel economy for the base level. (7) For alcohol dual fuel automobiles and natural gas dual... diesel test fuel. (ii) Calculate the city, highway, and combined fuel economy values from the tests... fuel economy values for the model type. (5) For alcohol dual fuel automobiles and natural gas dual fuel...

  7. Aviation Fuel Tracer Simulation: Model Intercomparison and Implications

    Science.gov (United States)

    Danilin, M. Y.; Fahey, D. W.; Schumann, U.; Prather, M. J.; Penner, J. E.; Ko, M. K. W.; Weisenstein, D. K.; Jackman, C. H.; Pitari, G.; Koehler, I.; Sausen, R.; Weaver, C. J.; Douglass, A. R.; Connell, P. S.; Kinnison, D. E.; Dentener, F. J.; Fleming, E. L.; Berntsen, T. K.; Isaksen, I. S. A.

    1998-01-01

    An upper limit for aircraft-produced perturbations to aerosols and gaseous exhaust products in the upper troposphere and lower stratosphere (UT/LS) is derived using the 1992 aviation fuel tracer simulation performed by eleven global atmospheric models. Key findings are that subsonic aircraft emissions: (1) have not been responsible for the observed water vapor trends at 40degN; (2) could be a significant source of soot mass near 12 km, but not at 20 km; (3) might cause a noticeable increase in the background sulfate aerosol surface area and number densities (but not mass density) near the northern mid-latitude tropopause; and (4) could provide a global, annual mean top of the atmosphere radiative forcing up to +0.006 W/sq m and -0.013 W/sq m due to emitted soot and sulfur, respectively.

  8. Modeling and Structural Optimization of Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Panagakos, Grigorios

    The research conducted in the context of this PhD, lies on the cross section between multi-scale modeling of flow in porous media, electrochemical diffusion and reaction, in combination with Shape and Structural Optimization techniques. More specifi-cally, we have followed two lines of action...... requirements. On the one hand, it needs to secure the intake of fuel into the cell, fact that would require an as low hydraulic resistance as possible, i.e. ideally an open channel and on the other hand to exhibit an as high as possible electronic conductance, which in the ideal case would mean an area blocked...... completely by a material with high conductivity such as coated stainless steel. The balance between these two competing, oppositely driving forces, indicate that there should be a design that satisfies in the best way both. Similar problems have been successfully dealt by structural-topology optimization...

  9. The FIT 2.0 Model - Fuel-cycle Integration and Tradeoffs

    Energy Technology Data Exchange (ETDEWEB)

    Steven J. Piet; Nick R. Soelberg; Layne F. Pincock; Eric L. Shaber; Gregory M Teske

    2011-06-01

    All mass streams from fuel separation and fabrication are products that must meet some set of product criteria – fuel feedstock impurity limits, waste acceptance criteria (WAC), material storage (if any), or recycle material purity requirements such as zirconium for cladding or lanthanides for industrial use. These must be considered in a systematic and comprehensive way. The FIT model and the “system losses study” team that developed it [Shropshire2009, Piet2010b] are steps by the Fuel Cycle Technology program toward an analysis that accounts for the requirements and capabilities of each fuel cycle component, as well as major material flows within an integrated fuel cycle. This will help the program identify near-term R&D needs and set longer-term goals. This report describes FIT 2, an update of the original FIT model.[Piet2010c] FIT is a method to analyze different fuel cycles; in particular, to determine how changes in one part of a fuel cycle (say, fuel burnup, cooling, or separation efficiencies) chemically affect other parts of the fuel cycle. FIT provides the following: Rough estimate of physics and mass balance feasibility of combinations of technologies. If feasibility is an issue, it provides an estimate of how performance would have to change to achieve feasibility. Estimate of impurities in fuel and impurities in waste as function of separation performance, fuel fabrication, reactor, uranium source, etc.

  10. The FIT 2.0 Model - Fuel-cycle Integration and Tradeoffs

    Energy Technology Data Exchange (ETDEWEB)

    Steven J. Piet; Nick R. Soelberg; Layne F. Pincock; Eric L. Shaber; Gregory M Teske

    2011-06-01

    All mass streams from fuel separation and fabrication are products that must meet some set of product criteria – fuel feedstock impurity limits, waste acceptance criteria (WAC), material storage (if any), or recycle material purity requirements such as zirconium for cladding or lanthanides for industrial use. These must be considered in a systematic and comprehensive way. The FIT model and the “system losses study” team that developed it [Shropshire2009, Piet2010b] are steps by the Fuel Cycle Technology program toward an analysis that accounts for the requirements and capabilities of each fuel cycle component, as well as major material flows within an integrated fuel cycle. This will help the program identify near-term R&D needs and set longer-term goals. This report describes FIT 2, an update of the original FIT model.[Piet2010c] FIT is a method to analyze different fuel cycles; in particular, to determine how changes in one part of a fuel cycle (say, fuel burnup, cooling, or separation efficiencies) chemically affect other parts of the fuel cycle. FIT provides the following: Rough estimate of physics and mass balance feasibility of combinations of technologies. If feasibility is an issue, it provides an estimate of how performance would have to change to achieve feasibility. Estimate of impurities in fuel and impurities in waste as function of separation performance, fuel fabrication, reactor, uranium source, etc.

  11. A proposed model of factors influencing hydrogen fuel cell vehicle acceptance

    Science.gov (United States)

    Imanina, N. H. Noor; Kwe Lu, Tan; Fadhilah, A. R.

    2016-03-01

    Issues such as environmental problem and energy insecurity keep worsening as a result of energy use from household to huge industries including automotive industry. Recently, a new type of zero emission vehicle, hydrogen fuel cell vehicle (HFCV) has received attention. Although there are argues on the feasibility of hydrogen as the future fuel, there is another important issue, which is the acceptance of HFCV. The study of technology acceptance in the early stage is a vital key for a successful introduction and penetration of a technology. This paper proposes a model of factors influencing green vehicle acceptance, specifically HFCV. This model is built base on two technology acceptance theories and other empirical studies of vehicle acceptance. It aims to provide a base for finding the key factors influencing new sustainable energy fuelled vehicle, HFCV acceptance which is achieved by explaining intention to accept HFCV. Intention is influenced by attitude, subjective norm and perceived behavioural control from Theory of Planned Behaviour and personal norm from Norm Activation Theory. In the framework, attitude is influenced by perceptions of benefits and risks, and social trust. Perceived behavioural control is influenced by government interventions. Personal norm is influenced by outcome efficacy and problem awareness.

  12. A More Complete Model for TCP Connections Established between One Server and Many Receivers

    Institute of Scientific and Technical Information of China (English)

    LINYu; CHENGShiduan; WUHaitao; WANGChonggang

    2003-01-01

    Different from previous TCP (transmis-sion control program) modeling works, this paper presents a more complete analytical model of multiple TCP con-nections established between a busy server and multiple receivers under two distinct cases: the case there is suffi-cient bandwidth and the case there is a bandwidth bottle-neck link between the server and receivers. In the former case, the server will become the bottleneck of the whole system, and TCP behaviors are different from the model presented before. However, in the latter case, multiple TCP connections will share the bandwidth of the bottle-neck link. Based on the analysis of working flows in the system and a M/G/1 queueing model, the RTT and long-term TCP throughput formulae are derived in terms of number of TCPs, packet loss rate, and end-to-end delay.And the effect of maximum window size is also investi-gated. The simulation results confirm that new model is more accurate than previous model.

  13. Toward verifying fossil fuel CO2 emissions with the CMAQ model: motivation, model description and initial simulation.

    Science.gov (United States)

    Liu, Zhen; Bambha, Ray P; Pinto, Joseph P; Zeng, Tao; Boylan, Jim; Huang, Maoyi; Lei, Huimin; Zhao, Chun; Liu, Shishi; Mao, Jiafu; Schwalm, Christopher R; Shi, Xiaoying; Wei, Yaxing; Michelsen, Hope A

    2014-04-01

    Motivated by the question of whether and how a state-of-the-art regional chemical transport model (CTM) can facilitate characterization of CO2 spatiotemporal variability and verify CO2 fossil-fuel emissions, we for the first time applied the Community Multiscale Air Quality (CMAQ) model to simulate CO2. This paper presents methods, input data, and initial results for CO2 simulation using CMAQ over the contiguous United States in October 2007. Modeling experiments have been performed to understand the roles of fossil-fuel emissions, biosphere-atmosphere exchange, and meteorology in regulating the spatial distribution of CO2 near the surface over the contiguous United States. Three sets of net ecosystem exchange (NEE) fluxes were used as input to assess the impact of uncertainty of NEE on CO2 concentrations simulated by CMAQ. Observational data from six tall tower sites across the country were used to evaluate model performance. In particular, at the Boulder Atmospheric Observatory (BAO), a tall tower site that receives urban emissions from Denver CO, the CMAQ model using hourly varying, high-resolution CO2 fossil-fuel emissions from the Vulcan inventory and Carbon Tracker optimized NEE reproduced the observed diurnal profile of CO2 reasonably well but with a low bias in the early morning. The spatial distribution of CO2 was found to correlate with NO(x), SO2, and CO, because of their similar fossil-fuel emission sources and common transport processes. These initial results from CMAQ demonstrate the potential of using a regional CTM to help interpret CO2 observations and understand CO2 variability in space and time. The ability to simulate a full suite of air pollutants in CMAQ will also facilitate investigations of their use as tracers for CO2 source attribution. This work serves as a proof of concept and the foundation for more comprehensive examinations of CO2 spatiotemporal variability and various uncertainties in the future. Atmospheric CO2 has long been modeled

  14. Evaluation of creep-fatigue life-prediction models for the solar central receiver

    Science.gov (United States)

    Hyzak, J. M.; Hughes, D. A.

    1981-09-01

    The applicability of several creep fatigue models to life prediction of boiler tubes in a solar central receiver (SCR) was evaluated. The SCR boiler tubes will experience compressive strain dwell loading with hold times up to 6 to 8 hours at temperatures where time dependent deformation will occur. The evaluation criteria include the ability of the model to account for mean stress effects and to be practical in the long life, small strain range regime. A correlation between maximum tensile stress and fatigue life is presented. Using this correlation, compressive dwell behavior is predicted based on continuous cycling data. The limits of this predictive scheme are addressed.

  15. Model of human breathing reflected signal received by PN-UWB radar.

    Science.gov (United States)

    Mabrouk, Mohamed; Rajan, Sreeraman; Bolic, Miodrag; Batkin, Izmail; Dajani, Hilmi R; Groza, Voicu Z

    2014-01-01

    Human detection is an integral component of civilian and military rescue operations, military surveillance and combat operations. Human detection can be achieved through monitoring of vital signs. In this article, a mathematical model of human breathing reflected signal received in PN-UWB radar is proposed. Unlike earlier published works, both chest and abdomen movements are considered for modeling the radar return signal along with the contributions of fundamental breathing frequency and its harmonics. Analyses of recorded reflected signals from three subjects in different postures and at different ranges from the radar indicate that ratios of the amplitudes of the harmonics contain information about posture and posture change.

  16. Application of Thermochemical Modeling to Assessment/Evaluation of Nuclear Fuel Behavior

    Energy Technology Data Exchange (ETDEWEB)

    Besmann, Theodore M [University of South Carolina, Columbia; McMurray, Jake W [ORNL; Simunovic, Srdjan [ORNL

    2016-01-01

    The combination of new fuel compositions and higher burn-ups envisioned for the future means that representing fuel properties will be much more important, and yet more complex. Behavior within the oxide fuel rods will be difficult to model owing to the high temperatures, and the large number of elements generated and their significant concentrations that are a result of fuels taken to high burn-up. This unprecedented complexity offers an enormous challenge to the thermochemical understanding of these systems and opportunities to advance solid solution models to describe these materials. This paper attempts to model and simulate that behavior using an oxide fuels thermochemical description to compute the equilibrium phase state and oxygen potential of LWR fuel under irradiation.

  17. A suitable model plant for control of the set fuel cell-DC/DC converter

    Energy Technology Data Exchange (ETDEWEB)

    Andujar, J.M.; Segura, F.; Vasallo, M.J. [Departamento de Ingenieria Electronica, Sistemas Informaticos y Automatica, E.P.S. La Rabida, Universidad de Huelva, Ctra. Huelva - Palos de la Frontera, S/N, 21819 La Rabida - Palos de la Frontera Huelva (Spain)

    2008-04-15

    In this work a state and transfer function model of the set made up of a proton exchange membrane (PEM) fuel cell and a DC/DC converter is developed. The set is modelled as a plant controlled by the converter duty cycle. In addition to allow setting the plant operating point at any point of its characteristic curve (two interesting points are maximum efficiency and maximum power points), this approach also allows the connection of the fuel cell to other energy generation and storage devices, given that, as they all usually share a single DC bus, a thorough control of the interconnected devices is required. First, the state and transfer function models of the fuel cell and the converter are obtained. Then, both models are related in order to achieve the fuel cell+DC/DC converter set (plant) model. The results of the theoretical developments are validated by simulation on a real fuel cell model. (author)

  18. Modeling defect and fission gas properties in U-Si fuels

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Anders David Ragnar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stanek, Christopher Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Noordhoek, Mark J. [Univ. of South Carolina, Columbia, SC (United States); Besmann, Theodore M. [Univ. of South Carolina, Columbia, SC (United States); Middleburgh, Simon C. [Westinghouse Electric Sweden, Vasteras (Sweden); Lahoda, E. J. [Westinghouse Electric Company LLC, Cranberry Woods, PA (United States); Chernatynskiy, Aleksandr [Missouri Univ. of Science and Technology, Rolla, MO (United States); Grimes, Robin W. [Imperial College, London (United Kingdom)

    2017-04-14

    Uranium silicides, in particular U3Si2, are being explored as an advanced nuclear fuel with increased accident tolerance as well as competitive economics compared to the baseline UO2 fuel. They benefit from high thermal conductivity (metallic) compared to UO2 fuel (insulator or semi-conductor) used in current Light Water Reactors (LWRs). The U-Si fuels also have higher fissile density. In order to perform meaningful engineering scale nuclear fuel performance simulations, the material properties of the fuel, including the response to irradiation environments, must be known. Unfortunately, the data available for USi fuels are rather limited, in particular for the temperature range where LWRs would operate. The ATF HIP is using multi-scale modeling and simulations to address this knowledge gap.

  19. Modeling defect and fission gas properties in U-Si fuels

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Anders David Ragnar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stanek, Christopher Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Noordhoek, Mark [Univ. of South Carolina, Columbia, SC (United States); Besmann, Theodore [Univ. of South Carolina, Columbia, SC (United States); Middleburgh, Simon C. [Westinghouse Electric Sweden, Vasteras (Sweden); Lahoda, E. J. [Westinghouse Electric Company LLC, Cranberry Woods, PA (United States); Chernatynskiy, Aleksandr [Missouri University of Science and Technology; Grimes, Robin W. [Imperial College, London (United Kingdom)

    2017-04-27

    Uranium silicides, in particular U3Si2, are being explored as an advanced nuclear fuel with increased accident tolerance as well as competitive economics compared to the baseline UO2 fuel. They benefit from high thermal conductivity (metallic) compared to UO2 fuel (insulator or semi-conductor) used in current Light Water Reactors (LWRs). The U-Si fuels also have higher fissile density. In order to perform meaningful engineering scale nuclear fuel performance simulations, the material properties of the fuel, including the response to irradiation environments, must be known. Unfortunately, the data available for USi fuels are rather limited, in particular for the temperature range where LWRs would operate. The ATF HIP is using multi-scale modeling and simulations to address this knowledge gap.

  20. Ab Initio Enhanced calphad Modeling of Actinide-Rich Nuclear Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, Dane [Univ. of Wisconsin, Madison, WI (United States); Yang, Yong Austin [Univ. of Wisconsin, Madison, WI (United States)

    2013-10-28

    The process of fuel recycling is central to the Advanced Fuel Cycle Initiative (AFCI), where plutonium and the minor actinides (MA) Am, Np, and Cm are extracted from spent fuel and fabricated into new fuel for a fast reactor. Metallic alloys of U-Pu-Zr-MA are leading candidates for fast reactor fuels and are the current basis for fast spectrum metal fuels in a fully recycled closed fuel cycle. Safe and optimal use of these fuels will require knowledge of their multicomponent phase stability and thermodynamics (Gibbs free energies). In additional to their use as nuclear fuels, U-Pu-Zr-MA contain elements and alloy phases that pose fundamental questions about electronic structure and energetics at the forefront of modern many-body electron theory. This project will validate state-of-the-art electronic structure approaches for these alloys and use the resulting energetics to model U-Pu-Zr-MA phase stability. In order to keep the work scope practical, researchers will focus on only U-Pu-Zr-{Np,Am}, leaving Cm for later study. The overall objectives of this project are to: Provide a thermodynamic model for U-Pu-Zr-MA for improving and controlling reactor fuels; and, Develop and validate an ab initio approach for predicting actinide alloy energetics for thermodynamic modeling.

  1. Advanced fuel cycle cost estimation model and its cost estimation results for three nuclear fuel cycles using a dynamic model in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sungki, E-mail: sgkim1@kaeri.re.kr [Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Ko, Wonil [Korea Atomic Energy Research Institute, 1045 Daedeokdaero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Youn, Saerom; Gao, Ruxing [University of Science and Technology, 217 Gajungro, Yuseong-gu, Daejeon 305-350 (Korea, Republic of); Bang, Sungsig, E-mail: ssbang@kaist.ac.kr [Korea Advanced Institute of Science and Technology, Department of Business and Technology Management, 291 Deahak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2015-11-15

    Highlights: • The nuclear fuel cycle cost using a new cost estimation model was analyzed. • The material flows of three nuclear fuel cycle options were calculated. • The generation cost of once-through was estimated to be 66.88 mills/kW h. • The generation cost of pyro-SFR recycling was estimated to be 78.06 mills/kW h. • The reactor cost was identified as the main cost driver of pyro-SFR recycling. - Abstract: The present study analyzes advanced nuclear fuel cycle cost estimation models such as the different discount rate model and its cost estimation results. To do so, an analysis of the nuclear fuel cycle cost of three options (direct disposal (once through), PWR–MOX (Mixed OXide fuel), and Pyro-SFR (Sodium-cooled Fast Reactor)) from the viewpoint of economic sense, focusing on the cost estimation model, was conducted using a dynamic model. From an analysis of the fuel cycle cost estimation results, it was found that some cost gap exists between the traditional same discount rate model and the advanced different discount rate model. However, this gap does not change the priority of the nuclear fuel cycle option from the viewpoint of economics. In addition, the fuel cycle costs of OT (Once-Through) and Pyro-SFR recycling based on the most likely value using a probabilistic cost estimation except for reactor costs were calculated to be 8.75 mills/kW h and 8.30 mills/kW h, respectively. Namely, the Pyro-SFR recycling option was more economical than the direct disposal option. However, if the reactor cost is considered, the economic sense in the generation cost between the two options (direct disposal vs. Pyro-SFR recycling) can be changed because of the high reactor cost of an SFR.

  2. Detailed Multi-dimensional Modeling of Direct Internal Reforming Solid Oxide Fuel Cells.

    Science.gov (United States)

    Tseronis, K; Fragkopoulos, I S; Bonis, I; Theodoropoulos, C

    2016-06-01

    Fuel flexibility is a significant advantage of solid oxide fuel cells (SOFCs) and can be attributed to their high operating temperature. Here we consider a direct internal reforming solid oxide fuel cell setup in which a separate fuel reformer is not required. We construct a multidimensional, detailed model of a planar solid oxide fuel cell, where mass transport in the fuel channel is modeled using the Stefan-Maxwell model, whereas the mass transport within the porous electrodes is simulated using the Dusty-Gas model. The resulting highly nonlinear model is built into COMSOL Multiphysics, a commercial computational fluid dynamics software, and is validated against experimental data from the literature. A number of parametric studies is performed to obtain insights on the direct internal reforming solid oxide fuel cell system behavior and efficiency, to aid the design procedure. It is shown that internal reforming results in temperature drop close to the inlet and that the direct internal reforming solid oxide fuel cell performance can be enhanced by increasing the operating temperature. It is also observed that decreases in the inlet temperature result in smoother temperature profiles and in the formation of reduced thermal gradients. Furthermore, the direct internal reforming solid oxide fuel cell performance was found to be affected by the thickness of the electrochemically-active anode catalyst layer, although not always substantially, due to the counter-balancing behavior of the activation and ohmic overpotentials.

  3. Integration of computational modeling and experimental techniques to design fuel surrogates

    DEFF Research Database (Denmark)

    Choudhury, H.A.; Intikhab, S.; Kalakul, Sawitree

    2017-01-01

    Conventional gasoline comprises of a large number of hydrocarbons that makes it difficult to utilize in a model for prediction of its properties. Modeling is needed for a better understanding of the fuel flow and combustion behavior that are essential to enhance fuel quality and improve engine pe...

  4. Water Balance Simulations of a PEM Fuel Cell Using a Two-Fluid Model

    DEFF Research Database (Denmark)

    Berning, Torsten; Odgaard, Madeleine; Kær, Søren Knudsen

    2010-01-01

    A previously published computational multi-phase model of a polymer-electrolyte membrane fuel cell has been extended in order to account for the anode side and the electrolyte membrane. The model has been applied to study the water balance of a fuel cell during operation under various humidificat...

  5. Modeling of a HTPEM fuel cell using Adaptive Neuro-Fuzzy Inference Systems

    DEFF Research Database (Denmark)

    Justesen, Kristian Kjær; Andreasen, Søren Juhl; Sahlin, Simon Lennart

    2015-01-01

    In this work an Adaptive Neuro-Fuzzy Inference System (ANFIS) model of the voltage of a fuel cell is developed. The inputs of this model are the fuel cell temperature, current density and the carbon monoxide concentration of the anode supply gas. First an identification experiment which spans...

  6. Optical property characterization of molten salt mixtures for thermal modeling of volumetrically absorbing solar receiver applications

    Science.gov (United States)

    Tetreault-Friend, Melanie; McKrell, Thomas; Baglietto, Emilio; Gil, Antoni; Slocum, Alexander H.; Calvet, Nicolas

    2017-06-01

    A method for experimentally determining the attenuation coefficient of high temperature semi-transparent liquids for volumetrically absorbing solar receiver applications was developed. The method was used to measure the attenuation coefficient over a broad spectral range in a 40 wt. % KNO3:60 wt. % NaNO3 binary nitrate molten salt mixture (solar salt). The measured absorption bands extend over 98% of the re-emission spectrum of the salt, indicating that thermal redistribution within the salt itself via radiative participating media effects is negligible. In addition, the effects of the salt's purity and thermal decomposition on the optical properties were also investigated and the light penetration depth is shown to vary significantly in the presence of impurities. The implications of these results for solar receiver design and modeling are discussed.

  7. FMCW CSAR Doppler shifting correction and the layover phenomenon analysising at a new received signal model

    Science.gov (United States)

    Song, Depeng; Qu, Yi; Xie, Yuehui

    2016-10-01

    Because of go-stop mode not applying to FMCW CSAR (frequency modulated continuous wave circular synthetic aperture radar), received signal include Doppler shifting result from the radar fly in one period, which have a bad effect on the quality of imaging in wide-field FMCW CSAR. However the compensation functions of liner SAR are not suitable for CSAR. To solve the problem, the paper rebuild a received mode and elicit the Doppler shifting. At the same time, based on the model, the paper analysis the layover phenomenon while obtaining two-dimensional (2D) representations of 3D large scenes due to the wide-field FMCW CSAR and simulate the phenomenon. By the simulation, the effect of the layover can be expressed clearly.

  8. Research of power fuel low-temperature vortex combustion in industrial boiler based on numerical modelling

    Directory of Open Access Journals (Sweden)

    Orlova K.Y.

    2017-01-01

    Full Text Available The goal of the presented research is to perform numerical modelling of fuel low-temperature vortex combustion in once-through industrial steam boiler. Full size and scaled-down furnace model created with FIRE 3D software and was used for the research. All geometrical features were observed. The baseline information for the low-temperature vortex furnace process are velocity and temperature of low, upper and burner blast, air-fuel ratio, fuel consumption, coal dust size range. The obtained results are: temperature and velocity three dimensional fields, furnace gases and solid fuel ash particles concentration.

  9. Comprehensive Reactive Receiver Modeling for Diffusive Molecular Communication Systems: Reversible Binding, Molecule Degradation, and Finite Number of Receptors

    CERN Document Server

    Ahmadzadeh, Arman; Burkovski, Andreas; Schober, Robert

    2016-01-01

    This paper studies the problem of receiver modeling in molecular communication systems. We consider the diffusive molecular communication channel between a transmitter nano-machine and a receiver nano-machine in a fluid environment. The information molecules released by the transmitter nano-machine into the environment can degrade in the channel via a first-order degradation reaction and those that reach the receiver nano-machine can participate in a reversible bimolecular reaction with receiver receptor proteins. Thereby, we distinguish between two scenarios. In the first scenario, we assume that the entire surface of the receiver is covered by receptor molecules. We derive a closed-form analytical expression for the expected received signal at the receiver, i.e., the expected number of activated receptors on the surface of the receiver. Then, in the second scenario, we consider the case where the number of receptor molecules is finite and the uniformly distributed receptor molecules cover the receiver surfa...

  10. FRAPCON-3: Modifications to fuel rod material properties and performance models for high-burnup application

    Energy Technology Data Exchange (ETDEWEB)

    Lanning, D.D.; Beyer, C.E.; Painter, C.L.

    1997-12-01

    This volume describes the fuel rod material and performance models that were updated for the FRAPCON-3 steady-state fuel rod performance code. The property and performance models were changed to account for behavior at extended burnup levels up to 65 Gwd/MTU. The property and performance models updated were the fission gas release, fuel thermal conductivity, fuel swelling, fuel relocation, radial power distribution, solid-solid contact gap conductance, cladding corrosion and hydriding, cladding mechanical properties, and cladding axial growth. Each updated property and model was compared to well characterized data up to high burnup levels. The installation of these properties and models in the FRAPCON-3 code along with input instructions are provided in Volume 2 of this report and Volume 3 provides a code assessment based on comparison to integral performance data. The updated FRAPCON-3 code is intended to replace the earlier codes FRAPCON-2 and GAPCON-THERMAL-2. 94 refs., 61 figs., 9 tabs.

  11. Modeling and Parameterization of Fuel Economy in Heavy Duty Vehicles (HDVs

    Directory of Open Access Journals (Sweden)

    Yunjung Oh

    2014-08-01

    Full Text Available The present paper suggests fuel consumption modeling for HDVs based on the code from the Japanese Ministry of the Environment. Two interpolation models (inversed distance weighted (IDW and Hermite and three types of fuel efficiency maps (coarse, medium, and dense were adopted to determine the most appropriate combination for further studies. Finally, sensitivity analysis studies were conducted to determine which parameters greatly impact the fuel efficiency prediction results for HDVs. While vitiating each parameter at specific percentages (±1%, ±3%, ±5%, ±10%, the change rate of the fuel efficiency results was analyzed, and the main factors affecting fuel efficiency were summarized. As a result, the Japanese transformation algorithm program showed good agreement with slightly increased prediction accuracy for the fuel efficiency test results when applying the Hermite interpolation method compared to IDW interpolation. The prediction accuracy of fuel efficiency remained unchanged regardless of the chosen fuel efficiency map data density. According to the sensitivity analysis study, three parameters (fuel consumption map data, driving force, and gross vehicle weight have the greatest impact on fuel efficiency (±5% to ±10% changes.

  12. A multiphase interfacial model for the dissolution of spent nuclear fuel

    Science.gov (United States)

    Jerden, James L.; Frey, Kurt; Ebert, William

    2015-07-01

    The Fuel Matrix Dissolution Model (FMDM) is an electrochemical reaction/diffusion model for the dissolution of spent uranium oxide fuel. The model was developed to provide radionuclide source terms for use in performance assessment calculations for various types of geologic repositories. It is based on mixed potential theory and consists of a two-phase fuel surface made up of UO2 and a noble metal bearing fission product phase in contact with groundwater. The corrosion potential at the surface of the dissolving fuel is calculated by balancing cathodic and anodic reactions occurring at the solution interfaces with UO2 and NMP surfaces. Dissolved oxygen and hydrogen peroxide generated by radiolysis of the groundwater are the major oxidizing agents that promote fuel dissolution. Several reactions occurring on noble metal alloy surfaces are electrically coupled to the UO2 and can catalyze or inhibit oxidative dissolution of the fuel. The most important of these is the oxidation of hydrogen, which counteracts the effects of oxidants (primarily H2O2 and O2). Inclusion of this reaction greatly decreases the oxidation of U(IV) and slows fuel dissolution significantly. In addition to radiolytic hydrogen, large quantities of hydrogen can be produced by the anoxic corrosion of steel structures within and near the fuel waste package. The model accurately predicts key experimental trends seen in literature data, the most important being the dramatic depression of the fuel dissolution rate by the presence of dissolved hydrogen at even relatively low concentrations (e.g., less than 1 mM). This hydrogen effect counteracts oxidation reactions and can limit fuel degradation to chemical dissolution, which results in radionuclide source term values that are four or five orders of magnitude lower than when oxidative dissolution processes are operative. This paper presents the scientific basis of the model, the approach for modeling used fuel in a disposal system, and preliminary

  13. Fuel Cell Power Model Version 2: Startup Guide, System Designs, and Case Studies. Modeling Electricity, Heat, and Hydrogen Generation from Fuel Cell-Based Distributed Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Steward, D.; Penev, M.; Saur, G.; Becker, W.; Zuboy, J.

    2013-06-01

    This guide helps users get started with the U.S. Department of Energy/National Renewable Energy Laboratory Fuel Cell Power (FCPower) Model Version 2, which is a Microsoft Excel workbook that analyzes the technical and economic aspects of high-temperature fuel cell-based distributed energy systems with the aim of providing consistent, transparent, comparable results. This type of energy system would provide onsite-generated heat and electricity to large end users such as hospitals and office complexes. The hydrogen produced could be used for fueling vehicles or stored for later conversion to electricity.

  14. Modeling, analysis and control of fuel cell hybrid power systems

    Science.gov (United States)

    Suh, Kyung Won

    Transient performance is a key characteristic of fuel cells, that is sometimes more critical than efficiency, due to the importance of accepting unpredictable electric loads. To fulfill the transient requirement in vehicle propulsion and portable fuel cell applications, a fuel cell stack is typically coupled with a battery through a DC/DC converter to form a hybrid power system. Although many power management strategies already exist, they all rely on low level controllers that realize the power split. In this dissertation we design controllers that realize various power split strategies by directly manipulating physical actuators (low level commands). We maintain the causality of the electric dynamics (voltage and current) and investigate how the electric architecture affects the hybridization level and the power management. We first establish the performance limitations associated with a stand-alone and power-autonomous fuel cell system that is not supplemented by an additional energy storage and powers all its auxiliary components by itself. Specifically, we examine the transient performance in fuel cell power delivery as it is limited by the air supplied by a compressor driven by the fuel cell itself. The performance limitations arise from the intrinsic coupling in the fluid and electrical domain between the compressor and the fuel cell stack. Feedforward and feedback control strategies are used to demonstrate these limitations analytically and with simulations. Experimental tests on a small commercial fuel cell auxiliary power unit (APU) confirm the dynamics and the identified limitations. The dynamics associated with the integration of a fuel cell system and a DC/DC converter is then investigated. Decentralized and fully centralized (using linear quadratic techniques) controllers are designed to regulate the power system voltage and to prevent fuel cell oxygen starvation. Regulating these two performance variables is a difficult task and requires a compromise

  15. Modeling of PEM fuel cell Pt/C catalyst degradation

    Science.gov (United States)

    Bi, Wu; Fuller, Thomas F.

    Pt/C catalyst degradation remains as one of the primary limitations for practical applications of proton exchange membrane (PEM) fuel cells. Pt catalyst degradation mechanisms with the typically observed Pt nanoparticle growth behaviors have not been completely understood and predicted. In this work, a physics-based Pt/C catalyst degradation model is proposed with a simplified bi-modal particle size distribution. The following catalyst degradation processes were considered: (1) dissolution of Pt and subsequent electrochemical deposition on Pt nanoparticles in cathode; (2) diffusion of Pt ions in the membrane electrode assembly (MEA); and (3) Pt ion chemical reduction in membrane by hydrogen permeating through the membrane from the negative electrode. Catalyst coarsening with Pt nanoparticle growth was clearly demonstrated by Pt mass exchange between small and large particles through Pt dissolution and Pt ion deposition. However, the model is not adequate to predict well the catalyst degradation rates including Pt nanoparticle growth, catalyst surface area loss and cathode Pt mass loss. Additional catalyst degradation processes such as new Pt cluster formation on carbon support and neighboring Pt clusters coarsening was proposed for further simulative investigation.

  16. Modeling and Simulation for Fuel Cell Polymer Electrolyte Membrane

    Directory of Open Access Journals (Sweden)

    Takahiro Hayashi

    2013-01-01

    Full Text Available We have established methods to evaluate key properties that are needed to commercialize polyelectrolyte membranes for fuel cell electric vehicles such as water diffusion, gas permeability, and mechanical strength. These methods are based on coarse-graining models. For calculating water diffusion and gas permeability through the membranes, the dissipative particle dynamics–Monte Carlo approach was applied, while mechanical strength of the hydrated membrane was simulated by coarse-grained molecular dynamics. As a result of our systematic search and analysis, we can now grasp the direction necessary to improve water diffusion, gas permeability, and mechanical strength. For water diffusion, a map that reveals the relationship between many kinds of molecular structures and diffusion constants was obtained, in which the direction to enhance the diffusivity by improving membrane structure can be clearly seen. In order to achieve high mechanical strength, the molecular structure should be such that the hydrated membrane contains narrow water channels, but these might decrease the proton conductivity. Therefore, an optimal design of the polymer structure is needed, and the developed models reviewed here make it possible to optimize these molecular structures.

  17. Computational fluid dynamics modelling of a polymer electrolyte membrane fuel cell under transient automotive operations

    OpenAIRE

    Choopanya, Pattarapong

    2016-01-01

    A polymer electrolyte membrane (PEM) fuel cell is probably the most promising technology that will replace conventional internal combustion engines in the near future. As a primary power source for an automobile, the transient performance of a PEM fuel cell is of prime importance. In this thesis, a comprehensive, three-dimensional, two-phase, multi-species computational fuel cell dynamics model is developed in order to investigate the effect of flow-field design on the magnitude of current ov...

  18. Advancements in the behavioral modeling of fuel elements and related structures

    Energy Technology Data Exchange (ETDEWEB)

    Billone, M.C.; Montgomery, R.O.; Rashid, Y.R.; Head, J.L. (Argonne National Lab., IL (USA); ANATECH Research Corp., San Diego, CA (USA); Royal Naval Coll., Greenwich (UK))

    1989-01-01

    An important aspect of the design and analysis of nuclear reactors is the ability to predict the behavior of fuel elements in the adverse environment of a reactor system. By understanding the thermomechanical behavior of the different materials which constitute a nuclear fuel element, analysis and predictions can be made regarding the integrity and reliability of fuel element designs. The SMiRT conference series, through the division on fuel elements and the post-conference seminars on fuel element modeling, provided technical forums for the international participation in the exchange of knowledge concerning the thermomechanical modeling of fuel elements. This paper discusses the technical advances in the behavioral modeling of fuel elements presented at the SMiRT conference series since its inception in 1971. Progress in the areas of material properties and constitutive relationships, modeling methodologies, and integral modeling approaches was reviewed and is summarized in light of their impact on the thermomechanical modeling of nuclear fuel elements. 34 refs., 5 tabs.

  19. User Guide for VISION 3.4.7 (Verifiable Fuel Cycle Simulation) Model

    Energy Technology Data Exchange (ETDEWEB)

    Jacob J. Jacobson; Robert F. Jeffers; Gretchen E. Matthern; Steven J. Piet; Wendell D. Hintze

    2011-07-01

    The purpose of this document is to provide a guide for using the current version of the Verifiable Fuel Cycle Simulation (VISION) model. This is a complex model with many parameters and options; the user is strongly encouraged to read this user guide before attempting to run the model. This model is an R&D work in progress and may contain errors and omissions. It is based upon numerous assumptions. This model is intended to assist in evaluating 'what if' scenarios and in comparing fuel, reactor, and fuel processing alternatives at a systems level. The model is not intended as a tool for process flow and design modeling of specific facilities nor for tracking individual units of fuel or other material through the system. The model is intended to examine the interactions among the components of a fuel system as a function of time varying system parameters; this model represents a dynamic rather than steady-state approximation of the nuclear fuel system. VISION models the nuclear cycle at the system level, not individual facilities, e.g., 'reactor types' not individual reactors and 'separation types' not individual separation plants. Natural uranium can be enriched, which produces enriched uranium, which goes into fuel fabrication, and depleted uranium (DU), which goes into storage. Fuel is transformed (transmuted) in reactors and then goes into a storage buffer. Used fuel can be pulled from storage into either separation or disposal. If sent to separations, fuel is transformed (partitioned) into fuel products, recovered uranium, and various categories of waste. Recycled material is stored until used by its assigned reactor type. VISION is comprised of several Microsoft Excel input files, a Powersim Studio core, and several Microsoft Excel output files. All must be co-located in the same folder on a PC to function. You must use Powersim Studio 8 or better. We have tested VISION with the Studio 8 Expert, Executive, and Education versions

  20. Modeling of thermo-mechanical and irradiation behavior of mixed oxide fuel for sodium fast reactors

    Science.gov (United States)

    Karahan, Aydın; Buongiorno, Jacopo

    2010-01-01

    An engineering code to model the irradiation behavior of UO2-PuO2 mixed oxide fuel pins in sodium-cooled fast reactors was developed. The code was named fuel engineering and structural analysis tool (FEAST-OXIDE). FEAST-OXIDE has several modules working in coupled form with an explicit numerical algorithm. These modules describe: (1) fission gas release and swelling, (2) fuel chemistry and restructuring, (3) temperature distribution, (4) fuel-clad chemical interaction and (5) fuel-clad mechanical analysis. Given the fuel pin geometry, composition and irradiation history, FEAST-OXIDE can analyze fuel and cladding thermo-mechanical behavior at both steady-state and design-basis transient scenarios. The code was written in FORTRAN-90 program language. The mechanical analysis module implements the LIFE algorithm. Fission gas release and swelling behavior is described by the OGRES and NEFIG models. However, the original OGRES model has been extended to include the effects of joint oxide gain (JOG) formation on fission gas release and swelling. A detailed fuel chemistry model has been included to describe the cesium radial migration and JOG formation, oxygen and plutonium radial distribution and the axial migration of cesium. The fuel restructuring model includes the effects of as-fabricated porosity migration, irradiation-induced fuel densification, grain growth, hot pressing and fuel cracking and relocation. Finally, a kinetics model is included to predict the clad wastage formation. FEAST-OXIDE predictions have been compared to the available FFTF, EBR-II and JOYO databases, as well as the LIFE-4 code predictions. The agreement was found to be satisfactory for steady-state and slow-ramp over-power accidents.

  1. WRF fire simulation coupled with a fuel moisture model and smoke transport by WRF-Chem

    CERN Document Server

    Kochanski, Adam K; Mandel, Jan; Kim, Minjeong

    2012-01-01

    We describe two recent additions to WRF coupled with a fire spread model. Fire propagation is strongly dependent on fuel moisture, which in turn depends on the history of the atmosphere. We have implemented a equilibrium time-lag model of fuel moisture driven by WRF variables. The code allows the user to specify fuel parameters, with the defaults calibrated to the Canadian fire danger rating system for 10-hour fuel. The moisture model can run coupled with the atmosphere-fire model, or offline from WRF output to equilibrate the moisture over a period of time and to provide initial moisture conditions for a coupled atmosphere-fire-moisture simulation. The fire model also inserts smoke tracers into WRF-Chem to model the transport of fire emissions. The coupled model is available from OpenWFM.org. An earlier version of the fire model coupled with atmosphere is a part of WRF release.

  2. Modeling and Analysis of FCM UN TRISO Fuel Using the PARFUME Code

    Energy Technology Data Exchange (ETDEWEB)

    Blaise Collin

    2013-09-01

    The PARFUME (PARticle Fuel ModEl) modeling code was used to assess the overall fuel performance of uranium nitride (UN) tri-structural isotropic (TRISO) ceramic fuel in the frame of the design and development of Fully Ceramic Matrix (FCM) fuel. A specific modeling of a TRISO particle with UN kernel was developed with PARFUME, and its behavior was assessed in irradiation conditions typical of a Light Water Reactor (LWR). The calculations were used to access the dimensional changes of the fuel particle layers and kernel, including the formation of an internal gap. The survivability of the UN TRISO particle was estimated depending on the strain behavior of the constituent materials at high fast fluence and burn-up. For nominal cases, internal gas pressure and representative thermal profiles across the kernel and layers were determined along with stress levels in the pyrolytic carbon (PyC) and silicon carbide (SiC) layers. These parameters were then used to evaluate fuel particle failure probabilities. Results of the study show that the survivability of UN TRISO fuel under LWR irradiation conditions might only be guaranteed if the kernel and PyC swelling rates are limited at high fast fluence and burn-up. These material properties are unknown at the irradiation levels expected to be reached by UN TRISO fuel in LWRs. Therefore, more effort is needed to determine them and positively conclude on the applicability of FCM fuel to LWRs.

  3. Impacts and implementation of fuel moisture release and radiation properties in modelling of pulverized fuel combustion processes

    DEFF Research Database (Denmark)

    Yin, Chungen

    2015-01-01

    Pulverized fuels (PF) prepared and fired in utility boilers usually contain a certain amount of moisture, either free moisture or chemically bound moisture. In PF furnaces, radiation which is the principal mode of heat transfer consists of contribution from both gas and particle phase. This paper...... presents different methods for fuel moisture release and new models for gas and particle radiative properties, and demonstrates their implementation, importance and impacts in PF combustion modelling via a comprehensive CFD study of a pulverized coal-fired utility boiler. To conclude, it is recommended...... to add the free moisture into the primary air stream while lump the moisture retained in the feed after the mills with volatiles in PF combustion modelling. For gas and particle radiation in PF boilers, it is found that particle radiation largely overwhelms gas radiation due to high particle loading...

  4. Axisymmetric whole pin life modelling of advanced gas-cooled reactor nuclear fuel

    Science.gov (United States)

    Mella, R.; Wenman, M. R.

    2013-06-01

    Thermo-mechanical contributions to pellet-clad interaction (PCI) in advanced gas-cooled reactors (AGRs) are modelled in the ABAQUS finite element (FE) code. User supplied sub-routines permit the modelling of the non-linear behaviour of AGR fuel through life. Through utilisation of ABAQUS's well-developed pre- and post-processing ability, the behaviour of the axially constrained steel clad fuel was modelled. The 2D axisymmetric model includes thermo-mechanical behaviour of the fuel with time and condition dependent material properties. Pellet cladding gap dynamics and thermal behaviour are also modelled. The model treats heat up as a fully coupled temperature-displacement study. Dwell time and direct power cycling was applied to model the impact of online refuelling, a key feature of the AGR. The model includes the visco-plastic behaviour of the fuel under the stress and irradiation conditions within an AGR core and a non-linear heat transfer model. A multiscale fission gas release model is applied to compute pin pressure; this model is coupled to the PCI gap model through an explicit fission gas inventory code. Whole pin, whole life, models are able to show the impact of the fuel on all segments of cladding including weld end caps and cladding pellet locking mechanisms (unique to AGR fuel). The development of this model in a commercial FE package shows that the development of a potentially verified and future-proof fuel performance code can be created and used. The usability of a FE based fuel performance code would be an enhancement over past codes. Pre- and post-processors have lowered the entry barrier for the development of a fuel performance model to permit the ability to model complicated systems. Typical runtimes for a 5 year axisymmetric model takes less than one hour on a single core workstation. The current model has implemented: Non-linear fuel thermal behaviour, including a complex description of heat flow in the fuel. Coupled with a variety of

  5. Identifying the European fossil fuel plumes in the atmosphere over the Northeast Atlantic Region through isotopic observations and numerical modelling

    DEFF Research Database (Denmark)

    Geels, C.; Christensen, J.H.; Hansen, A.W.;

    2006-01-01

    Atmospheric transport, C-14. fossil fuel CO_2, numerical modeling, the north East Atlantic Region Udgivelsesdato: 18 August......Atmospheric transport, C-14. fossil fuel CO_2, numerical modeling, the north East Atlantic Region Udgivelsesdato: 18 August...

  6. MELCOR model for an experimental 17x17 spent fuel PWR assembly.

    Energy Technology Data Exchange (ETDEWEB)

    Cardoni, Jeffrey

    2010-11-01

    A MELCOR model has been developed to simulate a pressurized water reactor (PWR) 17 x 17 assembly in a spent fuel pool rack cell undergoing severe accident conditions. To the extent possible, the MELCOR model reflects the actual geometry, materials, and masses present in the experimental arrangement for the Sandia Fuel Project (SFP). The report presents an overview of the SFP experimental arrangement, the MELCOR model specifications, demonstration calculation results, and the input model listing.

  7. Evaluating potential benefits of burning lower quality fuel oils using the oil burn optimization model

    Energy Technology Data Exchange (ETDEWEB)

    Babilonia, P.

    1995-09-01

    As a result of a 1987 New York State Public Service Commission Audit of Niagara Mohawk`s Fuel Supply operations, Niagara Mohawk (NMPC) became interested in analyzing the plant performance impacts of burning fuels of differing qualities at its various generating stations. Black & Veatch (B&V) had previously developed a computer model for EPRI that analyzed coal quality impacts (i.e., Coal Quality Impact Model). As a result of B&V`s work, NMPC contracted with B&V to first develop custom-designed software for its coal stations (Coal Burn Optimization Model (CBOM)). Subsequently, B&V was retained to develop a similar designed software for its oil stations, Oswego and Albany Steam Stations. The Oil Burn Optimization Model (OBOM) was, therefore, developed. OBOM was designed to be used to evaluate residual fuel oil supply options by predicting their fuel-related plant operating and maintenance costs. Fuel oil-related costs can also be compared to natural gas-related costs. Costs are estimated by predicting performance of various plant equipment. Predictions focus on combustion calculations, material flows, auxiliary power, boiler efficiency, precipitator and fan performance, fuel pumping and preheating requirements, and corrosion considerations. Total costs at the busbar attributed to fuel are calculated from these predictions. OBOM is a PC-based system operating under MS-DOS. The model produces hard copy results for quick comparison of fuels and their potential effects on plant operating and maintenance costs.

  8. PEM fuel cell catalyst degradation mechanism and mathematical modeling

    Science.gov (United States)

    Bi, Wu

    The durability of carbon-supported platinum oxygen reduction electrocatalysts is one of the limiting factors for their commercial applications in PEM fuel cell cathodes. In this work, we applied both experimental and numerical tools to study Pt/C catalyst degradation mechanisms. An accelerated catalyst degradation protocol through cycling the cathode potential in a square-wave profile was applied to study cell performances, Pt/C catalyst ORR activity, and active surface area losses. Post-mortem analyses of cathode Pt particle size were conducted by X-ray diffraction. Changes of platinum distributions in CCMs were studied by SEM/EDS analyses with surface coated Au as the reference element. The mechanisms of platinum deposition in membrane were investigated. It was confirmed by the SEM/EDS Pt distribution analyses that the deposited Pt atoms originated from the cathode. It was hypothesized that dissolved Pt ions from the cathode diffused into the membrane and were reduced by the permeated hydrogen from the anode. These deposited Pt atoms catalyzed the combustion of permeated oxygen and hydrogen. Pt band was predicted and experimentally confirmed at the location where the permeated hydrogen and oxygen completely reacted with each other. An active research thrust for PEM fuel cells is the development of membranes for high temperature (above 80°C) and low humidity operations. However a large tradeoff the benefits running fuel cell at relatively high temperatures was observed due to the accelerated cathode degradation processes. And at low humidity conditions, the cathode degradation rate decreased due to the slow transport of soluble platinum ions in possible narrowed/limited water (or ionic) channel networks in polymer electrolytes. From the Pt dissolution experiments in 0.5 M HClO4 solution, large positive effects of holding potentials on dissolution rates and soluble Pt concentrations were observed. Without an external holding potential, Pt dissolution rate was

  9. Performance of Cooperative Eigenvalue Spectrum Sensing with a Realistic Receiver Model under Impulsive Noise

    Directory of Open Access Journals (Sweden)

    Dayan A. Guimarães

    2013-01-01

    Full Text Available In this paper we present a unified comparison of the performance of four detection techniques for centralized data-fusion cooperative spectrum sensing in cognitive radio networks under impulsive noise, namely, the eigenvalue-based generalized likelihood ratio test (GLRT, the maximum-minimum eigenvalue detection (MMED, the maximum eigenvalue detection (MED, and the energy detection (ED. We consider two system models: an implementation-oriented model that includes the most relevant signal processing tasks realized by a real cognitive radio receiver, and the theoretical model conventionally adopted in the literature. We show that under the implementation-oriented model, GLRT and MMED are quite robust under impulsive noise, whereas the performance of MED and ED is drastically degraded. We also show that performance under the conventional model can be too pessimistic if impulsive noise is present, whereas it can be too optimistic in the absence of this impairment. We also discuss the fact that impulsive noise is not such a severe problem when we take into account the more realistic implementation-oriented model.

  10. Modeling and control of a small solar fuel cell hybrid energy system

    Institute of Scientific and Technical Information of China (English)

    LI Wei; ZHU Xin-jian; CAO Guang-yi

    2007-01-01

    This paper describes a solar photovoltaic fuel cell (PVEC) hybrid generation system consisting of a photovoltaic (PV) generator, a proton exchange membrane fuel cell (PEMFC), an electrolyser, a supercapacitor, a storage gas tank and power conditioning unit (PCU). The load is supplied from the PV generator with a fuel cell working in parallel. Excess PV energy when available is converted to hydrogen using an electrolyser for later use in the fuel cell. The individual mathematical model for each component is presented. Control strategy for the system is described. MATLAB/Simulink is used for the simulation of this highly nonlinear hybrid energy system. The simulation results are shown in the paper.

  11. Nongray-gas Effects in Modeling of Large-scale Oxy-fuel Combustion Processes

    DEFF Research Database (Denmark)

    Yin, Chungen

    2012-01-01

    , among which radiative heat transfer under oxy-fuel conditions is one of the fundamental issues. This paper demonstrates the nongray-gas effects in modeling of large-scale oxy-fuel combustion processes. Oxy-fuel combustion of natural gas in a large-scale utility boiler is numerically investigated...... cases. The simulation results show that the gray and non-gray calculations of the same oxy-fuel WSGGM make distinctly different predictions in the wall radiative heat transfer, incident radiative flux, radiative source, gas temperature and species profiles. In relative to the non-gray implementation...

  12. A model for recovery of scrap monolithic uranium molybdenum fuel by electrorefining

    Science.gov (United States)

    Van Kleeck, Melissa A.

    The goal of the Reduced Enrichment for Research and Test Reactors program (RERTR) is toreduce enrichment at research and test reactors, thereby decreasing proliferation risk at these facilities. A new fuel to accomplish this goal is being manufactured experimentally at the Y12 National Security Complex. This new fuel will require its own waste management procedure,namely for the recovery of scrap from its manufacture. The new fuel is a monolithic uraniummolybdenum alloy clad in zirconium. Feasibility tests were conducted in the Planar Electrode Electrorefiner using scrap U-8Mo fuel alloy. These tests proved that a uranium product could be recovered free of molybdenum from this scrap fuel by electrorefining. Tests were also conducted using U-10Mo Zr clad fuel, which confirmed that product could be recovered from a clad version of this scrap fuel at an engineering scale, though analytical results are pending for the behavior of Zr in the electrorefiner. A model was constructed for the simulation of electrorefining the scrap material produced in the manufacture of this fuel. The model was implemented on two platforms, Microsoft Excel and MatLab. Correlations, used in the model, were developed experimentally, describing area specific resistance behavior at each electrode. Experiments validating the model were conducted using scrap of U-10Mo Zr clad fuel in the Planar Electrode Electrorefiner. The results of model simulations on both platforms were compared to experimental results for the same fuel, salt and electrorefiner compositions and dimensions for two trials. In general, the model demonstrated behavior similar to experimental data but additional refinements are needed to improve its accuracy. These refinements consist of a function for surface area at anode and cathode based on charge passed. Several approximations were made in the model concerning areas of electrodes which should be replaced by a more accurate function describing these areas.

  13. Challenges in spent nuclear fuel final disposal:conceptual design models

    Institute of Scientific and Technical Information of China (English)

    Mukhtar Ahmed RANA

    2008-01-01

    The disposal of spent nuclear fuel is a long-standing issue in nuclear technology. Mainly, UO2 and metallic U are used as a fuel in nuclear reactors. Spent nuclear fuel contains fission products and transuranium elements, which would remain radioactive for 104 to 108 years. In this brief communication, essential concepts and engineering elements related to high-level nuclear waste disposal are described. Conceptual design models are described and discussed considering the long-time scale activity of spent nuclear fuel or high level waste. Notions of physical and chemical barriers to contain nuclear waste are highlightened. Concerns regarding integrity, self-irradiation induced decomposition and thermal effects of decay heat on the spent nuclear fuel are also discussed. The question of retrievability of spent nuclear fuel after disposal is considered.

  14. Modelling of tubular-designed solid oxide fuel cell with indirect internal reforming operation fed by different primary fuels

    Science.gov (United States)

    Dokmaingam, P.; Assabumrungrat, S.; Soottitantawat, A.; Laosiripojana, N.

    Mathematical models of an indirect internal reforming solid oxide fuel cell (IIR-SOFC) fed by four different primary fuels, i.e., methane, biogas, methanol and ethanol, are developed based on steady-state, heterogeneous, two-dimensional and tubular-design SOFC models. The effect of fuel type on the thermal coupling between internal endothermic reforming with exothermic electrochemical reactions and system performance are determined. The simulation reveals that an IIR-SOFC fuelled by methanol provides the smoothest temperature gradient with high electrochemical efficiency. Furthermore, the content of CO 2 in biogas plays an important role on system performance since electrical efficiency is improved by the removal of some CO 2 from biogas but a larger temperature gradient is expected. Sensitivity analysis of three parameters, namely, a operating pressure, inlet steam to carbon (S:C) ratio and flow direction is then performed. By increasing the operating pressure up to 10 bar, the system efficiency increases and the temperature gradient can be minimized. The use of a high inlet S:C ratio reduces the cooling spot at the entrance of reformer channel but the electrical efficiency is considerably decreased. An IIR-SOFC with a counter-flow pattern (as based case) is compared with that with co-flow pattern (co-flow of air and fuel streams through fuel cell). The IIR-SOFC with co-flow pattern provides higher voltage and a smoother temperature gradient along the system due to superior matching between heat supplied from electrochemical reaction and heat required for steam reforming reaction; thus it is expected to be a better option for practical applications.

  15. Sensitivity to imputation models and assumptions in receiver operating characteristic analysis with incomplete data.

    Science.gov (United States)

    Karakaya, Jale; Karabulut, Erdem; Yucel, Recai M

    Modern statistical methods using incomplete data have been increasingly applied in a wide variety of substantive problems. Similarly, receiver operating characteristic (ROC) analysis, a method used in evaluating diagnostic tests or biomarkers in medical research, has also been increasingly popular problem in both its development and application. While missing-data methods have been applied in ROC analysis, the impact of model mis-specification and/or assumptions (e.g. missing at random) underlying the missing data has not been thoroughly studied. In this work, we study the performance of multiple imputation (MI) inference in ROC analysis. Particularly, we investigate parametric and non-parametric techniques for MI inference under common missingness mechanisms. Depending on the coherency of the imputation model with the underlying data generation mechanism, our results show that MI generally leads to well-calibrated inferences under ignorable missingness mechanisms.

  16. Simplified Modeling of Tropospheric Ozone Formation Considering Alternative Fuels Using

    Directory of Open Access Journals (Sweden)

    Leonardo Aragão Ferreira da Silva

    2014-07-01

    Full Text Available Brazilian cities have been constantly exposed to air quality episodes of high ozone concentrations (O3 . Known for not be emitted directly into the environment, O3 is a result of several chemical reactions of other pollutants emitted to atmosphere. The growth of vehicle fleet and government incentives for using alternative fuels like ethanol and Compressed Natural Gas (CNG are changing the Brazilian Metropolitan Areas in terms of acetaldehyde and formaldehyde emissions, Volatile Organic Compounds (VOC's present in the atmosphere and known to act on the kinetics of ozone. Driven by high concentrations of tropospheric ozone in urban/industry centers and its implications for environment and population health, the target of this work is understand the kinetics of ozone formation through the creation of a mathematical model in FORTRAN 90, describing a system of coupled ordinary differential equations able to represent a simplified mechanism of photochemical reactions in the Brazilian Metropolitan Area. Evaluating the concentration results of each pollutant were possible to observe the precursor’s influence on tropospheric ozone formation, which seasons were more conducive to this one and which are the influences of weather conditions on formation of photochemical smog.

  17. Field Measurement and Calibration of HDM-4 Fuel Consumption Model on Interstate Highway in Florida

    Directory of Open Access Journals (Sweden)

    Xin Jiao

    2015-03-01

    Full Text Available Fuel consumptions are measured by operating passenger car and tractor-trailer on two interstate roadway sites in Florida. Each site contains flexible pavement and rigid pavement with similar pavement, traffic and environmental condition. Field test reveals that the average fuel consumption differences between vehicle operating on flexible pavement and rigid pavement at given test condition are 4.04% for tractor-trailer and 2.50% for passenger car, with a fuel saving on rigid pavement. The fuel consumption differences are found statistically significant at 95% confidence level for both vehicle types. Test data are then used to calibrate the Highway Development and Management IV (HDM-4 fuel consumption model and model coefficients are obtained for three sets of observations. Field measurement and prediction by calibrated model shows generally good agreement. Nevertheless, verification and adjustment with more experiment or data sources would be expected in future studies.

  18. Validation of PAGE-B model in Asian chronic hepatitis B patients receiving entecavir or tenofovir.

    Science.gov (United States)

    Kim, Mi Na; Hwang, Seong Gyu; Rim, Kyu Sung; Kim, Beom Kyung; Park, Jun Yong; Kim, Do Young; Ahn, Sang Hoon; Han, Kwang-Hyub; Kim, Seung Up

    2017-04-18

    A new hepatocellular carcinoma risk prediction model, PAGE-B, which includes age, gender and platelet count as constituent variables, has recently been proposed in Caucasian chronic hepatitis B patients. We validated PAGE-B model and compared its accuracy with that of conventional risk prediction models in Asian chronic hepatitis B patients. Chronic hepatitis B patients treated with entecavir or tenofovir were consecutively recruited. The performance of PAGE-B and three conventional risk prediction models (CU-HCC, GAG-HCC and REACH-B) were analysed. A total of 1092 chronic hepatitis B patients (668 men, 61.2%) were selected between August 2006 and January 2015. The mean age was 48 years. During the follow-up period (median, 43.6 months), 36 (3.3%) patients developed hepatocellular carcinoma. Older age (hazard ratio [HR]=1.077), male gender (HR=3.676) and lower platelet count (HR=0.984) were independent predictors of hepatocellular carcinoma development. The PAGE-B showed similar area under receiver operating characteristic curves (AUROCs) to GAG-HCC and CU-HCC at 3 years (0.777 vs 0.793 and 0.743, respectively; all P>.05) and 5 years (0.799 vs 0.803 and 0.744, respectively; all P>.05), whereas the AUROCs of PAGE-B were significantly higher than those of the REACH-B (0.602 at 3 years and 0.572 at 5 years, P<.05). Our study demonstrated that PAGE-B is applicable to Asian chronic hepatitis B patients receiving ETV or TDF therapy. The PAGE-B showed similar predictive performance to GAG-HCC and CU-HCC. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Fuel load modeling from mensuration attributes in temperate forests in northern Mexico

    Science.gov (United States)

    Maricela Morales-Soto; Marín Pompa-Garcia

    2013-01-01

    The study of fuels is an important factor in defining the vulnerability of ecosystems to forest fires. The aim of this study was to model a dead fuel load based on forest mensuration attributes from forest management inventories. A scatter plot analysis was performed and, from explanatory trends between the variables considered, correlation analysis was carried out...

  20. Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen

    2008-01-01

    This work presents the development of an equivalent circuit model of a 65 cell high temperature PEM (HTPEM) fuel cell stack using Electrochemical Impedance Spectroscopy (EIS). The HTPEM fuel cell membranes used are PBI-based and uses phosphoric acid as proton conductor. The operating temperature...

  1. Development of steady-state model for MSPT and detailed analyses of receiver

    Science.gov (United States)

    Yuasa, Minoru; Sonoda, Masanori; Hino, Koichi

    2016-05-01

    Molten salt parabolic trough system (MSPT) uses molten salt as heat transfer fluid (HTF) instead of synthetic oil. The demonstration plant of MSPT was constructed by Chiyoda Corporation and Archimede Solar Energy in Italy in 2013. Chiyoda Corporation developed a steady-state model for predicting the theoretical behavior of the demonstration plant. The model was designed to calculate the concentrated solar power and heat loss using ray tracing of incident solar light and finite element modeling of thermal energy transferred into the medium. This report describes the verification of the model using test data on the demonstration plant, detailed analyses on the relation between flow rate and temperature difference on the metal tube of receiver and the effect of defocus angle on concentrated power rate, for solar collector assembly (SCA) development. The model is accurate to an extent of 2.0% as systematic error and 4.2% as random error. The relationships between flow rate and temperature difference on metal tube and the effect of defocus angle on concentrated power rate are shown.

  2. Experimental Measurement and Numerical Modeling of the Effective Thermal Conductivity of TRISO Fuel Compacts

    Energy Technology Data Exchange (ETDEWEB)

    Folsom, Charles [Utah State Univ., Logan, UT (United States). Mechanical and Aerospace Engineering Dept.; Xing, Changhu [Utah State Univ., Logan, UT (United States). Mechanical and Aerospace Engineering Dept.; Jensen, Colby [Utah State Univ., Logan, UT (United States). Mechanical and Aerospace Engineering Dept.; Ban, Heng [Utah State Univ., Logan, UT (United States). Mechanical and Aerospace Engineering Dept.; Marshall, Douglas W. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    Accurate modeling capability of thermal conductivity of tristructural-isotropic (TRISO) fuel compacts is important to fuel performance modeling and safety of Generation IV reactors. To date, the effective thermal conductivity (ETC) of tristructural-isotropic (TRISO) fuel compacts has not been measured directly. The composite fuel is a complicated structure comprised of layered particles in a graphite matrix. In this work, finite element modeling is used to validate an analytic ETC model for application to the composite fuel material for particle-volume fractions up to 40%. The effect of each individual layer of a TRISO particle is analyzed showing that the overall ETC of the compact is most sensitive to the outer layer constituent. In conjunction with the modeling results, the thermal conductivity of matrix-graphite compacts and the ETC of surrogate TRISO fuel compacts have been successfully measured using a previously developed measurement system. The ETC of the surrogate fuel compacts varies between 50 and 30 W m-1 K-1 over a temperature range of 50-600°C. As a result of the numerical modeling and experimental measurements of the fuel compacts, a new model and approach for analyzing the effect of compact constituent materials on ETC is proposed that can estimate the fuel compact ETC with approximately 15-20% more accuracy than the old method. Using the ETC model with measured thermal conductivity of the graphite matrix-only material indicate that, in the composite form, the matrix material has a much greater thermal conductivity, which is attributed to the high anisotropy of graphite thermal conductivity. Therefore, simpler measurements of individual TRISO compact constituents combined with an analytic ETC model, will not provide accurate predictions of overall ETC of the compacts emphasizing the need for measurements of composite, surrogate compacts.

  3. Discrete Modeling of Early-Life Thermal Fracture in Ceramic Nuclear Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, Benjamin W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Huang, Hai [Idaho National Lab. (INL), Idaho Falls, ID (United States); Dolbow, John E. [Duke Univ., Durham, NC (United States); Hales, Jason D. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    Fracturing of ceramic fuel pellets heavily influences performance of light water reactor (LWR) fuel. Early in the life of fuel, starting with the initial power ramp, large thermal gradients cause high tensile hoop and axial stresses in the outer region of the fuel pellets, resulting in the formation of radial and axial cracks. Circumferential cracks form due to thermal gradients that occur when the power is ramped down. These thermal cracks cause the fuel to expand radially, closing the pellet/cladding gap and enhancing the thermal conductance across that gap, while decreasing the effective conductivity of the fuel in directions normal to the cracking. At lower length scales, formation of microcracks is an important contributor to the decrease in bulk thermal conductivity that occurs over the life of the fuel as the burnup increases. Because of the important effects that fracture has on fuel performance, a realistic, physically based fracture modeling capability is essential to predict fuel behavior in a wide variety of normal and abnormal conditions. Modeling fracture within the context of the finite element method, which is based on continuous interpolations of solution variables, has always been challenging because fracture is an inherently discontinuous phenomenon. Work is underway at Idaho National Laboratory to apply two modeling techniques model fracture as a discrete displacement discontinuity to nuclear fuel: The extended finite element method (XFEM), and discrete element method (DEM). XFEM is based on the standard finite element method, but with enhancements to represent discontinuous behavior. DEM represents a solid as a network of particles connected by bonds, which can arbitrarily fail if a fracture criterion is reached. This paper presents initial results applying the aforementioned techniques to model fuel fracturing. This work has initially focused on early life behavior of ceramic LWR fuel. A coupled thermal-mechanical XFEM method that includes

  4. Mechanical modelling of transient- to- failure SFR fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Feria, F.; Herranz, L. E.

    2014-07-01

    The response of Sodium Fast Reactor (SFR) fuel rods to transient accident conditions is an important safety concern. During transients the cladding strain caused by the stress due to pellet cladding mechanical interaction (PCMI) can lead to failure. Due to the fact that SFR fuel rods are commonly clad with strengthened material made of stainless steel (SS), cladding is usually treated as an elastic-perfectly-plastic material. However, viscoplastic behaviour can contribute to mechanical strain at high temperature (> 1000 K). (Author)

  5. Modeling of Fuel Film Cooling on Chamber Hot Wall

    Science.gov (United States)

    2014-07-01

    wall-normal Cartesian coordinate y+ = dimensionless y-spacing at wall CEA = Chemical Equilibrium with Applications (computer program) CFD ...Introduction The walls of liquid rocket engine chambers and nozzles must contain large pressures while being exposed to very high temperature gases, and...The physical and chemical phenomena involved in hydrocarbon FFC is notionally represented in Fig. 1. Hydrocarbon fuel at the fuel tank temperature

  6. Fuel Used for Off-Road Recreation: A Reassessment of the Fuel Use Model

    Energy Technology Data Exchange (ETDEWEB)

    Davis, S.C.; Truett, L.F.; Hu, P.S.

    1999-07-01

    The Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) established a National Recreational Trails Funding Program and the National Recreational Trails Trust Fund. ISTEA required that certain tax revenue generated from the sales of motor fuel used for off-road recreation be transferred from the Highway Trust Funds to the Trails Trust Fund for recreational trail and facility improvements. In order to apportion the Trails Trust Fund to individual States equitably, the Federal Highway Administration (FHWA) asked the Oak Ridge National Laboratory (ORNL) in 1993 to estimate the amount of motor fuel used for off-road recreation in the State level by different vehicle types. A modification of the methodology developed by ORNL has been used to apportion funds to the States since that time.

  7. A phenomenological model of two-phase (air/fuel droplet developing and breakup

    Directory of Open Access Journals (Sweden)

    Pavlović Radomir R.

    2013-01-01

    Full Text Available Effervescent atomization namely the air-filled liquid atomization comprehends certain complex two-phase phenomenon that are difficult to be modeled. Just a few researchers have found the mathematical expressions for description of the complex atomization model of the two-phase mixture air/diesel fuel. In the following review, developing model of twophase (air/fuel droplet of Cummins spray pump-injector is shown. The assumption of the same diameters of the droplet and the opening of the atomizer is made, while the air/fuel mass ratio inside the droplet varies.

  8. Using a prescribed fire to test custom and standard fuel models for fire behaviour prediction in a non-native, grass-invaded tropical dry shrubland

    Science.gov (United States)

    Andrew D. Pierce; Sierra McDaniel; Mark Wasser; Alison Ainsworth; Creighton M. Litton; Christian P. Giardina; Susan Cordell; Ralf Ohlemuller

    2014-01-01

    Questions: Do fuel models developed for North American fuel types accurately represent fuel beds found in grass-invaded tropical shrublands? Do standard or custom fuel models for firebehavior models with in situ or RAWS measured fuel moistures affect the accuracy of predicted fire behavior in grass-invaded tropical shrublands? Location: Hawai’i Volcanoes National...

  9. A Theoretical Solid Oxide Fuel Cell Model for Systems Controls and Stability Design

    Science.gov (United States)

    Kopasakis, George; Brinson, Thomas; Credle, Sydni

    2008-01-01

    As the aviation industry moves toward higher efficiency electrical power generation, all electric aircraft, or zero emissions and more quiet aircraft, fuel cells are sought as the technology that can deliver on these high expectations. The hybrid solid oxide fuel cell system combines the fuel cell with a micro-turbine to obtain up to 70% cycle efficiency, and then distributes the electrical power to the loads via a power distribution system. The challenge is to understand the dynamics of this complex multidiscipline system and the design distributed controls that take the system through its operating conditions in a stable and safe manner while maintaining the system performance. This particular system is a power generation and a distribution system, and the fuel cell and micro-turbine model fidelity should be compatible with the dynamics of the power distribution system in order to allow proper stability and distributed controls design. The novelty in this paper is that, first, the case is made why a high fidelity fuel cell mode is needed for systems control and stability designs. Second, a novel modeling approach is proposed for the fuel cell that will allow the fuel cell and the power system to be integrated and designed for stability, distributed controls, and other interface specifications. This investigation shows that for the fuel cell, the voltage characteristic should be modeled but in addition, conservation equation dynamics, ion diffusion, charge transfer kinetics, and the electron flow inherent impedance should also be included.

  10. System analysis with improved thermo-mechanical fuel rod models for modeling current and advanced LWR materials in accident scenarios

    Science.gov (United States)

    Porter, Ian Edward

    A nuclear reactor systems code has the ability to model the system response in an accident scenario based on known initial conditions at the onset of the transient. However, there has been a tendency for these codes to lack the detailed thermo-mechanical fuel rod response models needed for accurate prediction of fuel rod failure. This proposed work will couple today's most widely used steady-state (FRAPCON) and transient (FRAPTRAN) fuel rod models with a systems code TRACE for best-estimate modeling of system response in accident scenarios such as a loss of coolant accident (LOCA). In doing so, code modifications will be made to model gamma heating in LWRs during steady-state and accident conditions and to improve fuel rod thermal/mechanical analysis by allowing axial nodalization of burnup-dependent phenomena such as swelling, cladding creep and oxidation. With the ability to model both burnup-dependent parameters and transient fuel rod response, a fuel dispersal study will be conducted using a hypothetical accident scenario under both PWR and BWR conditions to determine the amount of fuel dispersed under varying conditions. Due to the fuel fragmentation size and internal rod pressure both being dependent on burnup, this analysis will be conducted at beginning, middle and end of cycle to examine the effects that cycle time can play on fuel rod failure and dispersal. Current fuel rod and system codes used by the Nuclear Regulatory Commission (NRC) are compilations of legacy codes with only commonly used light water reactor materials, Uranium Dioxide (UO2), Mixed Oxide (U/PuO 2) and zirconium alloys. However, the events at Fukushima Daiichi and Three Mile Island accident have shown the need for exploration into advanced materials possessing improved accident tolerance. This work looks to further modify the NRC codes to include silicon carbide (SiC), an advanced cladding material proposed by current DOE funded research on accident tolerant fuels (ATF). Several

  11. Population pharmacokinetic/pharmacodynamic modeling of tumor growth kinetics in medullary thyroid cancer patients receiving cabozantinib.

    Science.gov (United States)

    Miles, Dale R; Wada, David R; Jumbe, Nelson L; Lacy, Steven A; Nguyen, Linh T

    2016-04-01

    Nonlinear mixed effects models were developed to describe the relationship between cabozantinib exposure and target lesion tumor size in a phase III study of patients with progressive metastatic medullary thyroid cancer. These models used cabozantinib exposure estimates from a previously published population pharmacokinetic model for cabozantinib in cancer patients that was updated with data from healthy-volunteer studies. Semi-mechanistic models predict well for tumors with static, increasing, or decreasing growth over time, but they were not considered adequate for predicting tumor sizes in medullary thyroid cancer patients, among whom an early reduction in tumor size was followed by a late stabilization phase in those receiving cabozantinib. A semi-empirical tumor model adequately predicted tumor profiles that were assumed to have a net growth rate constant that was piecewise continuous in the regions of 0-110 and 110-280 days. Emax models relating average concentration to average change in tumor size predicted that an average concentration of 79 and 58 ng/ml, respectively, would yield 50% of the maximum possible tumor reduction during the first 110 days of dosing and during the subsequent 110-280 days of dosing. Simulations of tumor responses showed that daily doses of 60 mg or greater are expected to provide a similar tumor reduction. Both model evaluation of observed data and simulation results suggested that the two protocol-defined cabozantinib dose reductions from 140 to 100 mg/day and from 100 to 60 mg/day are not projected to result in a marked reduction in target lesion regrowth.

  12. Characterization and Modeling of Received Signal Strength and Charging Time for Wireless Energy Transfer

    Directory of Open Access Journals (Sweden)

    Uthman Baroudi

    2015-01-01

    Full Text Available Wireless sensor networks can provide effective means for monitoring and controlling a wide range of applications. Recently, tremendous effort was directed towards devising sensors powered from ambient sources such as heat, wind, and vibration. Wireless energy transfer is another source that has attractive features that make it a promising candidate for supplying power to wireless sensor nodes. This paper is concerned with characterizing and modeling the charging time and received signal strength indicator for wireless energy transfer system. These parameters play a vital role in deciding the geometry of sensor network and the routing protocols to be deployed. The development of communication protocols for wireless-powered wireless sensor networks is also improved with the knowledge of such models. These two quantities were computed from data acquired at various coordinates of the harvester relative to a fixed position of RF energy source. Data was acquired for indoor and outdoor scenarios using the commercially available PowerCast energy harvester and evaluation board. Mathematical models for both indoor and outdoor environments were developed and analyzed. A few guidelines on how to use these models were suggested. Finally, the possibility of harvesting the energy from the ambient RF power to energize wireless sensor nodes was also investigated.

  13. A multiphase interfacial model for the dissolution of spent nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

    Jerden, James L., E-mail: jerden@anl.gov [Argonne National Laboratory, 9700 South Cass Ave., Argonne, IL 60439 (United States); Frey, Kurt [University of Notre Dame, Notre Dame, IN 46556 (United States); Ebert, William [Argonne National Laboratory, 9700 South Cass Ave., Argonne, IL 60439 (United States)

    2015-07-15

    Highlights: • This model accounts for chemistry, temperature, radiolysis, U(VI) minerals, and hydrogen effect. • The hydrogen effect dominates processes determining spent fuel dissolution rate. • The hydrogen effect protects uranium oxide spent fuel from oxidative dissolution. - Abstract: The Fuel Matrix Dissolution Model (FMDM) is an electrochemical reaction/diffusion model for the dissolution of spent uranium oxide fuel. The model was developed to provide radionuclide source terms for use in performance assessment calculations for various types of geologic repositories. It is based on mixed potential theory and consists of a two-phase fuel surface made up of UO{sub 2} and a noble metal bearing fission product phase in contact with groundwater. The corrosion potential at the surface of the dissolving fuel is calculated by balancing cathodic and anodic reactions occurring at the solution interfaces with UO{sub 2} and NMP surfaces. Dissolved oxygen and hydrogen peroxide generated by radiolysis of the groundwater are the major oxidizing agents that promote fuel dissolution. Several reactions occurring on noble metal alloy surfaces are electrically coupled to the UO{sub 2} and can catalyze or inhibit oxidative dissolution of the fuel. The most important of these is the oxidation of hydrogen, which counteracts the effects of oxidants (primarily H{sub 2}O{sub 2} and O{sub 2}). Inclusion of this reaction greatly decreases the oxidation of U(IV) and slows fuel dissolution significantly. In addition to radiolytic hydrogen, large quantities of hydrogen can be produced by the anoxic corrosion of steel structures within and near the fuel waste package. The model accurately predicts key experimental trends seen in literature data, the most important being the dramatic depression of the fuel dissolution rate by the presence of dissolved hydrogen at even relatively low concentrations (e.g., less than 1 mM). This hydrogen effect counteracts oxidation reactions and can limit

  14. Source-receiver two-way wave extrapolation for prestack exploding-reflector modelling and migration

    KAUST Repository

    Alkhalifah, Tariq Ali

    2014-10-08

    Most modern seismic imaging methods separate input data into parts (shot gathers). We develop a formulation that is able to incorporate all available data at once while numerically propagating the recorded multidimensional wavefield forward or backward in time. This approach has the potential for generating accurate images free of artiefacts associated with conventional approaches. We derive novel high-order partial differential equations in the source-receiver time domain. The fourth-order nature of the extrapolation in time leads to four solutions, two of which correspond to the incoming and outgoing P-waves and reduce to the zero-offset exploding-reflector solutions when the source coincides with the receiver. A challenge for implementing two-way time extrapolation is an essential singularity for horizontally travelling waves. This singularity can be avoided by limiting the range of wavenumbers treated in a spectral-based extrapolation. Using spectral methods based on the low-rank approximation of the propagation symbol, we extrapolate only the desired solutions in an accurate and efficient manner with reduced dispersion artiefacts. Applications to synthetic data demonstrate the accuracy of the new prestack modelling and migration approach.

  15. Model documentation renewable fuels module of the National Energy Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-04-01

    This report documents the objectives, analytical approach, and design of the National Energy Modeling System (NEMS) Renewable Fuels Module (RFM) as it relates to the production of the 1997 Annual Energy Outlook forecasts. The report catalogues and describes modeling assumptions, computational methodologies, data inputs. and parameter estimation techniques. A number of offline analyses used in lieu of RFM modeling components are also described. This documentation report serves three purposes. First, it is a reference document for model analysts, model users, and the public interested in the construction and application of the RFM. Second, it meets the legal requirement of the Energy Information Administration (EIA) to provide adequate documentation in support of its models. Finally, such documentation facilitates continuity in EIA model development by providing information sufficient to perform model enhancements and data updates as part of EIA`s ongoing mission to provide analytical and forecasting information systems.

  16. Engineering model system study for a regenerative fuel cell: Study report

    Science.gov (United States)

    Chang, B. J.; Schubert, F. H.; Kovach, A. J.; Wynveen, R. A.

    1984-01-01

    Key design issues of the regenerative fuel cell system concept were studied and a design definition of an alkaline electrolyte based engineering model system or low Earth orbit missions was completed. Definition of key design issues for a regenerative fuel cell system include gaseous reactant storage, shared heat exchangers and high pressure pumps. A power flow diagram for the 75 kW initial space station and the impact of different regenerative fuel cell modular sizes on the total 5 year to orbit weight and volume are determined. System characteristics, an isometric drawing, component sizes and mass and energy balances are determined for the 10 kW engineering model system. An open loop regenerative fuel cell concept is considered for integration of the energy storage system with the life support system of the space station. Technical problems and their solutions, pacing technologies and required developments and demonstrations for the regenerative fuel cell system are defined.

  17. Integrating Fire Behavior Models and Geospatial Analysis for Wildland Fire Risk Assessment and Fuel Management Planning

    Directory of Open Access Journals (Sweden)

    Alan A. Ager

    2011-01-01

    Full Text Available Wildland fire risk assessment and fuel management planning on federal lands in the US are complex problems that require state-of-the-art fire behavior modeling and intensive geospatial analyses. Fuel management is a particularly complicated process where the benefits and potential impacts of fuel treatments must be demonstrated in the context of land management goals and public expectations. A number of fire behavior metrics, including fire spread, intensity, likelihood, and ecological risk must be analyzed for multiple treatment alternatives. The effect of treatments on wildfire impacts must be considered at multiple scales. The process is complicated by the lack of data integration among fire behavior models, and weak linkages to geographic information systems, corporate data, and desktop office software. This paper describes our efforts to build a streamlined fuel management planning and risk assessment framework, and an integrated system of tools for designing and testing fuel treatment programs on fire-prone wildlands.

  18. Evaluation and Model of Performance of A Tubular Solid Oxide Fuel Cell

    Institute of Scientific and Technical Information of China (English)

    JIA Jun-xi; SHEN Sheng-qiang

    2005-01-01

    A simulation model was developed to analyze the steady state and transient operation of a tubular solid oxide fuel cell. The model covers both the electrochemical and the heat transfer models. The electrochemical model deals with the Nernst potential, ohmic polarization, activation polarization, and concentration polarization, while the heat transfer model concerns the heat transfer by conduction, convection and radiation. The numerical results show that the ohmic loss is the dominant one among the three polarizations in a cathode-supported solid oxide fuel cell and in the middle part of a solid oxide fuel cell the temperature is higher than those at both the ends. When the inlet temperature and the flow rates of the fuel and the oxidant are kept constantly, the temperature of the solid structure of the cell will increase due to the increase of power output of the cell from the initial state to the new one.

  19. Hydrogen vehicle fueling station

    Energy Technology Data Exchange (ETDEWEB)

    Daney, D.E.; Edeskuty, F.J.; Daugherty, M.A. [Los Alamos National Lab., NM (United States)] [and others

    1995-09-01

    Hydrogen fueling stations are an essential element in the practical application of hydrogen as a vehicle fuel, and a number of issues such as safety, efficiency, design, and operating procedures can only be accurately addressed by a practical demonstration. Regardless of whether the vehicle is powered by an internal combustion engine or fuel cell, or whether the vehicle has a liquid or gaseous fuel tank, the fueling station is a critical technology which is the link between the local storage facility and the vehicle. Because most merchant hydrogen delivered in the US today (and in the near future) is in liquid form due to the overall economics of production and delivery, we believe a practical refueling station should be designed to receive liquid. Systems studies confirm this assumption for stations fueling up to about 300 vehicles. Our fueling station, aimed at refueling fleet vehicles, will receive hydrogen as a liquid and dispense it as either liquid, high pressure gas, or low pressure gas. Thus, it can refuel any of the three types of tanks proposed for hydrogen-powered vehicles -- liquid, gaseous, or hydride. The paper discusses the fueling station design. Results of a numerical model of liquid hydrogen vehicle tank filling, with emphasis on no vent filling, are presented to illustrate the usefulness of the model as a design tool. Results of our vehicle performance model illustrate our thesis that it is too early to judge what the preferred method of on-board vehicle fuel storage will be in practice -- thus our decision to accommodate all three methods.

  20. Model documentation renewable fuels module of the National Energy Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-06-01

    This report documents the objectives, analytical approach, and design of the National Energy Modeling System (NEMS) Renewable Fuels Module (RFM) as it relates to the production of the 1995 Annual Energy Outlook (AEO95) forecasts. The report catalogues and describes modeling assumptions, computational methodologies, data inputs, and parameter estimation techniques. A number of offline analyses used in lieu of RFM modeling components are also described. The RFM consists of six analytical submodules that represent each of the major renewable energy resources--wood, municipal solid waste (MSW), solar energy, wind energy, geothermal energy, and alcohol fuels. The RFM also reads in hydroelectric facility capacities and capacity factors from a data file for use by the NEMS Electricity Market Module (EMM). The purpose of the RFM is to define the technological, cost and resource size characteristics of renewable energy technologies. These characteristics are used to compute a levelized cost to be competed against other similarly derived costs from other energy sources and technologies. The competition of these energy sources over the NEMS time horizon determines the market penetration of these renewable energy technologies. The characteristics include available energy capacity, capital costs, fixed operating costs, variable operating costs, capacity factor, heat rate, construction lead time, and fuel product price.

  1. Model documentation renewable fuels module of the National Energy Modeling System

    Science.gov (United States)

    1995-06-01

    This report documents the objectives, analytical approach, and design of the National Energy Modeling System (NEMS) Renewable Fuels Module (RFM) as it relates to the production of the 1995 Annual Energy Outlook (AEO95) forecasts. The report catalogs and describes modeling assumptions, computational methodologies, data inputs, and parameter estimation techniques. A number of offline analyses used in lieu of RFM modeling components are also described. The RFM consists of six analytical submodules that represent each of the major renewable energy resources -- wood, municipal solid waste (MSW), solar energy, wind energy, geothermal energy, and alcohol fuels. The RFM also reads in hydroelectric facility capacities and capacity factors from a data file for use by the NEMS Electricity Market Module (EMM). The purpose of the RFM is to define the technological, cost, and resource size characteristics of renewable energy technologies. These characteristics are used to compute a levelized cost to be competed against other similarly derived costs from other energy sources and technologies. The competition of these energy sources over the NEMS time horizon determines the market penetration of these renewable energy technologies. The characteristics include available energy capacity, capital costs, fixed operating costs, variable operating costs, capacity factor, heat rate, construction lead time, and fuel product price.

  2. Modelling of automotive fuel droplet heating and evaporation: mathematical tools and approximations

    Science.gov (United States)

    Sazhin, Sergei S.; Qubeissi, Mansour Al

    2016-06-01

    New mathematical tools and approximations developed for the analysis of automotive fuel droplet heating and evaporation are summarised. The approach to modelling biodiesel fuel droplets is based on the application of the Discrete Component Model (DCM), while the approach to modelling Diesel fuel droplets is based on the application of the recently developed multi-dimensional quasi-discrete model. In both cases, the models are applied in combination with the Effective Thermal Conductivity/Effective Diffusivity model and the implementation in the numerical code of the analytical solutions to heat transfer and species diffusion equations inside droplets. It is shown that the approximation of biodiesel fuel by a single component leads to under-prediction of droplet evaporation time by up to 13% which can be acceptable as a crude approximation in some applications. The composition of Diesel fuel was simplified and reduced to only 98 components. The approximation of 98 components of Diesel fuel with 15 quasi-components/components leads to under-prediction of droplet evaporation time by about 3% which is acceptable in most engineering applications. At the same time, the approximation of Diesel fuel by a single component and 20 alkane components leads to a decrease in the evaporation time by about 19%, compared with the case of approximation of Diesel fuel with 98 components. The approximation of Diesel fuel with a single alkane quasi-component (C14.763H31.526) leads to under-prediction of the evaporation time by about 35% which is not acceptable even for qualitative analysis of the process. In the case when n-dodecane is chosen as the single alkane component, the above-mentioned under-prediction increases to about 44%.

  3. Development and verification of fuel burn-up calculation model in a reduced reactor geometry

    Energy Technology Data Exchange (ETDEWEB)

    Sembiring, Tagor Malem [Center for Reactor Technology and Nuclear Safety (PTKRN), National Nuclear Energy Agency (BATAN), Kawasan PUSPIPTEK Gd. No. 80, Serpong, Tangerang 15310 (Indonesia)], E-mail: tagorms@batan.go.id; Liem, Peng Hong [Research Laboratory for Nuclear Reactor (RLNR), Tokyo Institute of Technology (Tokyo Tech), O-okayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2008-02-15

    A fuel burn-up model in a reduced reactor geometry (2-D) is successfully developed and implemented in the Batan in-core fuel management code, Batan-FUEL. Considering the bank mode operation of the control rods, several interpolation functions are investigated which best approximate the 3-D fuel assembly radial power distributions across the core as function of insertion depth of the control rods. Concerning the applicability of the interpolation functions, it can be concluded that the optimal coefficients of the interpolation functions are not very sensitive to the core configuration and core or fuel composition in RSG GAS (MPR-30) reactor. Consequently, once the optimal interpolation function and its coefficients are derived then they can be used for 2-D routine operational in-core fuel management without repeating the expensive 3-D neutron diffusion calculations. At the selected fuel elements (at H-9 and G-6 core grid positions), the discrepancy of the FECFs (fuel element channel power peaking factors) between the 2-D and 3-D models are within the range of 3.637 x 10{sup -4}, 3.241 x 10{sup -4} and 7.556 x 10{sup -4} for the oxide, silicide cores with 250 g {sup 235}U/FE and the silicide core with 300 g {sup 235}U/FE, respectively.

  4. Dynamic modeling and simulation of air-breathing proton exchange membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Yalcinoz, T. [Department of Electrical and Computer Engineering, University of South Alabama, Mobile, AL 36688 (United States); Nigde University, Department of Electrical and Electronic Engineering, Nigde 51245 (Turkey); Alam, M.S. [Department of Electrical and Computer Engineering, University of South Alabama, Mobile, AL 36688 (United States)

    2008-07-15

    Small fuel cells have shown excellent potential as alternative energy sources for portable applications. One of the most promising fuel cell technologies for portable applications is air-breathing fuel cells. In this paper, a dynamic model of an air-breathing PEM fuel cell (AB-PEMFC) system is presented. The analytical modeling and simulation of the air-breathing PEM fuel cell system are verified using Matlab, Simulink and SimPowerSystems Blockset. To show the effectiveness of the proposed AB-PEMFC model, two case studies are carried out using the Matlab software package. In the first case study, the dynamic behavior of the proposed AB-PEMFC system is compared with that of a planar air-breathing PEM fuel cell model. In the second case study, the validation of the air-breathing PEM fuel cell-based power source is carried out for the portable application. Test results show that the proposed AB-PEMFC system can be considered as a viable alternative energy sources for portable applications. (author)

  5. OPTIMUM PLANNING OF EXPERIMENTS AT MODELING FUEL CONSUMPTION IN INTERNAL COMBUSTION ENGINES

    Directory of Open Access Journals (Sweden)

    N. Koshevoy

    2009-01-01

    Full Text Available The efficiency of optimum experiments planning by cost expenses at studying the processes of fuel consumption internal combustion engines is shown. The mathematical models of these processes in different state of engine working are synthesized.

  6. Modeling the Pyrochemical Reduction of Spent UO2 Fuel in a Pilot-Scale Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Steven D. Herrmann; Michael F. Simpson

    2006-08-01

    A kinetic model has been derived for the reduction of oxide spent nuclear fuel in a radial flow reactor. In this reaction, lithium dissolved in molten LiCl reacts with UO2 and fission product oxides to form a porous, metallic product. As the reaction proceeds, the depth of the porous layer around the exterior of each fuel particle increases. The observed rate of reaction has been found to be only dependent upon the rate of diffusion of lithium across this layer, consistent with a classic shrinking core kinetic model. This shrinking core model has been extended to predict the behavior of a hypothetical, pilot-scale reactor for oxide reduction. The design of the pilot-scale reactor includes forced flow through baskets that contain the fuel particles. The results of the modeling indicate that this is an essential feature in order to minimize the time needed to achieve full conversion of the fuel.

  7. Water Balance Simulations of a PEM Fuel Cell Using a Two-Fluid Model

    DEFF Research Database (Denmark)

    Berning, Torsten; Odgaard, Madeleine; Kær, Søren Knudsen

    2010-01-01

    A previously published computational multi-phase model of a polymer-electrolyte membrane fuel cell has been extended in order to account for the anode side and the electrolyte membrane. The model has been applied to study the water balance of a fuel cell during operation under various humidificat......A previously published computational multi-phase model of a polymer-electrolyte membrane fuel cell has been extended in order to account for the anode side and the electrolyte membrane. The model has been applied to study the water balance of a fuel cell during operation under various...... humidification conditions. It was found that the specific surface area of the electrolyte in the catalyst layers close to the membrane is of critical importance for the overall water balance. Applying a high specific electrolyte surface area close to the membrane (a water-uptake layer) always leads to a lower...

  8. Development of an empirical dynamic model for a Nexa PEM fuel cell power module

    Energy Technology Data Exchange (ETDEWEB)

    Soltani, Mehdi; Mohammad Taghi Bathaee, S. [Power Systems Laboratory, Department of Electrical Engineering, K.N. Toosi University of Technology, 16317-14191 Tehran (Iran)

    2010-12-15

    The goal of this study is to develop a fuel cell model which is capable of characterizing fuel cell steady-state performance as well as dynamic behavior. In this paper a new dynamic model of a 1.2 kW Polymer Electrolyte Membrane Fuel Cell (PEMFC) is developed and validated through a series of experiments. The experimental results have been obtained from a Nexa trademark PEM fuel cell power module under different load conditions. Based on this model, a simulator software package has been developed using the MATLAB {sup registered} and Simulink {sup registered} software and simulation results have been carried out. The proposed model exhibits good agreement with experiment results in steady-state and dynamic performance. (author)

  9. An earthquake transient method for pebble-bed reactors and a fuel temperature model for TRISO fueled reactors

    Science.gov (United States)

    Ortensi, Javier

    This investigation is divided into two general topics: (1) a new method for analyzing the safe shutdown earthquake event in a pebble bed reactor core, and (2) the development of an explicit tristructural-isotropic fuel model for high temperature reactors. The safe shutdown earthquake event is one of the design basis accidents for the pebble bed reactor. The new method captures the dynamic geometric compaction of the pebble bed core. The neutronic and thermal-fluids grids are dynamically re-meshed to simulate the re-arrangement of the pebbles in the reactor during the earthquake. Results are shown for the PBMR-400 assuming it is subjected to the Idaho National Laboratory's design basis earthquake. The study concludes that the PBMR-400 can safely withstand the reactivity insertions induced by the slumping of the core and the resulting relative withdrawal of the control rods. This characteristic stems from the large negative Doppler feedback of the fuel. This Doppler feedback mechanism is a major contributor to the passive safety of gas-cooled, graphite-moderated, high-temperature reactors that use fuel based on TRISO particles. The correct prediction of the magnitude and time-dependence of this feedback effect is essential to the conduct of safety analyses for these reactors. An explicit TRISO fuel temperature model named THETRIS has been developed in this work and incorporated in the CYNOD-THERMIX-KONVEK suite of coupled codes. The new model yields similar results to those obtained with more complex methods, requiring multi-TRISO calculations within one control volume. The performance of the code during fast and moderately-slow transients is verified. These analyses show how explicit TRISO models improve the predictions of the fuel temperature, and consequently, of the power escalation. In addition, a brief study of the potential effects on the transient behavior of high-temperature reactors due to the presence of a gap inside the TRISO particles is included

  10. Modeling and Simulation of a Nuclear Fuel Element Test Section

    Science.gov (United States)

    Moran, Robert P.; Emrich, William

    2011-01-01

    "The Nuclear Thermal Rocket Element Environmental Simulator" test section closely simulates the internal operating conditions of a thermal nuclear rocket. The purpose of testing is to determine the ideal fuel rod characteristics for optimum thermal heat transfer to their hydrogen cooling/working fluid while still maintaining fuel rod structural integrity. Working fluid exhaust temperatures of up to 5,000 degrees Fahrenheit can be encountered. The exhaust gas is rendered inert and massively reduced in temperature for analysis using a combination of water cooling channels and cool N2 gas injectors in the H2-N2 mixer portion of the test section. An extensive thermal fluid analysis was performed in support of the engineering design of the H2-N2 mixer in order to determine the maximum "mass flow rate"-"operating temperature" curve of the fuel elements hydrogen exhaust gas based on the test facilities available cooling N2 mass flow rate as the limiting factor.

  11. Model for the calculation of pressure loss through heavy fuel oil transfer pipelines

    Directory of Open Access Journals (Sweden)

    Hector Luis Laurencio-Alfonso,

    2012-10-01

    Full Text Available Considering the limitations of methodologies and empirical correlations in the evaluation of simultaneous effects produced by viscous and mix strength during the transfer of fluids through pipelines, this article presents the functional relationships that describe the pressure variations for the non-Newtonian fuel oil flowrate. The experimental study was conducted based on a characterization of the rheological behavior of fuel oil and modeling for a pseudoplastic behavior. The resulting model describes temperature changes, viscous friction effects and the effects of blending flow layers; which is therefore the basis of calculation for the selection, evaluation and rationalization of transport of heavy fuel oil by pipelines.

  12. On-Road Validation of a Simplified Model for Estimating Real-World Fuel Economy: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Wood, Eric; Gonder, Jeff; Jehlik, Forrest

    2017-01-01

    On-road fuel economy is known to vary significantly between individual trips in real-world driving conditions. This work introduces a methodology for rapidly simulating a specific vehicle's fuel economy over the wide range of real-world conditions experienced across the country. On-road test data collected using a highly instrumented vehicle is used to refine and validate this modeling approach. Model accuracy relative to on-road data collection is relevant to the estimation of 'off-cycle credits' that compensate for real-world fuel economy benefits that are not observed during certification testing on a chassis dynamometer.

  13. Modeling of Diffusive Convective and Electromechanical Processes in PEM fuel cells

    DEFF Research Database (Denmark)

    Bang, Mads

    and chemical species. Since analytical solutions to these three dimensional convections diffusion problems can rarely be obtained, the CFX code makes use of a finite volume discretization and numerical techniques, in order to obtain a solution. The model developed solves the convective and diffusive transport...... the fuel cells polarization curve and efficiency under operation. It is shown that the conductivity and the effective porosity of the catalyst layer, may strongly affect the performance of the fuel cell, and that it therefore should be considered when fuel cell models are made....

  14. Modeling of Fuel Film Cooling Using Steady State RANS and Unsteady DES Approaches

    Science.gov (United States)

    2016-07-27

    Briefing Charts 3. DATES COVERED (From - To) 21 July 2016 – 31 August 2016 4. TITLE AND SUBTITLE Modeling of Fuel Film Cooling Using Steady State RANS...Prescribed by ANSI Std. 239.18 1 Distribution A: Approved for Public Release; Distribution Unlimited. PA# 16391. Modeling of  Fuel  Film Cooling Using...Distribution Unlimited. PA# 16391. 3 Introduction • Fuel  film cooling is critical for high performing boost engines  using the Oxygen Rich Staged

  15. A Model to Predict Thermal Conductivity of Irradiated U-Mo Dispersion Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Burkes, Douglas; Huber, Tanja K.; Casella, Andrew M.

    2016-05-01

    The Office of Materials Management and Minimization Reactor Conversion Program continues to develop existing and new research and test reactor fuels to achieve maximum attainable uranium loadings to support the conversion of a number of the world’s remaining high-enriched uranium fueled reactors to low-enriched uranium fuel. The program is focused on assisting with the development and qualification of a fuel design that consists of a uranium-molybdenum (U-Mo) alloy dispersed in an aluminum matrix as one option for reactor conversion. Thermal conductivity is an important consideration in determining the operational temperature of the fuel and can be influenced by interaction layer formation between the dispersed phase and matrix and upon the concentration of the dispersed phase within the matrix. This paper extends the use of a simple model developed previously to study the influence of interaction layer formation as well as the size and volume fraction of fuel particles dispersed in the matrix, Si additions to the matrix, and Mo concentration in the fuel particles on the effective thermal conductivity of the U-Mo/Al composite during irradiation. The model has been compared to experimental measurements recently conducted on U-Mo/Al dispersion fuels at two different fission densities with acceptable agreement. Observations of the modeled results indicate that formation of an interaction layer and subsequent consumption of the matrix reveals a rather significant effect on effective thermal conductivity. The modeled interaction layer formation and subsequent consumption of the high thermal conductivity matrix was sensitive to the average dispersed fuel particle size, suggesting this parameter as one of the most effective in minimizing thermal conductivity degradation of the composite, while the influence of Si additions to the matrix in the model was highly dependent upon irradiation conditions.

  16. A model to predict thermal conductivity of irradiated U-Mo dispersion fuel

    Science.gov (United States)

    Burkes, Douglas E.; Huber, Tanja K.; Casella, Andrew M.

    2016-05-01

    Numerous global programs are focused on the continued development of existing and new research and test reactor fuels to achieve maximum attainable uranium loadings to support the conversion of a number of the world's remaining high-enriched uranium fueled reactors to low-enriched uranium fuel. Some of these programs are focused on assisting with the development and qualification of a fuel design that consists of a uranium-molybdenum (U-Mo) alloy dispersed in an aluminum matrix as one option for reactor conversion. Thermal conductivity is an important consideration in determining the operational temperature of the fuel and can be influenced by interaction layer formation between the dispersed phase and matrix and upon the concentration of the dispersed phase within the matrix. This paper extends the use of a simple model developed previously to study the influence of interaction layer formation as well as the size and volume fraction of fuel particles dispersed in the matrix, Si additions to the matrix, and Mo concentration in the fuel particles on the effective thermal conductivity of the U-Mo/Al composite during irradiation. The model has been compared to experimental measurements recently conducted on U-Mo/Al dispersion fuels at two different fission densities with acceptable agreement. Observations of the modeled results indicate that formation of an interaction layer and subsequent consumption of the matrix reveals a rather significant effect on effective thermal conductivity. The modeled interaction layer formation and subsequent consumption of the high thermal conductivity matrix was sensitive to the average dispersed fuel particle size, suggesting this parameter as one of the most effective in minimizing thermal conductivity degradation of the composite, while the influence of Si additions to the matrix in the model was highly dependent upon irradiation conditions.

  17. Hydrocarbon Fuel Thermal Performance Modeling based on Systematic Measurement and Comprehensive Chromatographic Analysis

    Science.gov (United States)

    2016-07-31

    distribution unlimited Hydrocarbon Fuel Thermal Performance Modeling based on Systematic Measurement and Comprehensive Chromatographic Analysis Matthew...Technical Note 3. DATES COVERED (From - To) 04 January 2016 - 31 July 2016 4. TITLE AND SUBTITLE Hydrocarbon Fuel Thermal Performance Modeling based on...Systematic Measurement and Comprehensive Chromatographic Analysis 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S

  18. Wildland Fire Behaviour Case Studies and Fuel Models for Landscape-Scale Fire Modeling

    Directory of Open Access Journals (Sweden)

    Paul-Antoine Santoni

    2011-01-01

    Full Text Available This work presents the extension of a physical model for the spreading of surface fire at landscape scale. In previous work, the model was validated at laboratory scale for fire spreading across litters. The model was then modified to consider the structure of actual vegetation and was included in the wildland fire calculation system Forefire that allows converting the two-dimensional model of fire spread to three dimensions, taking into account spatial information. Two wildland fire behavior case studies were elaborated and used as a basis to test the simulator. Both fires were reconstructed, paying attention to the vegetation mapping, fire history, and meteorological data. The local calibration of the simulator required the development of appropriate fuel models for shrubland vegetation (maquis for use with the model of fire spread. This study showed the capabilities of the simulator during the typical drought season characterizing the Mediterranean climate when most wildfires occur.

  19. Model documentation: Renewable Fuels Module of the National Energy Modeling System

    Science.gov (United States)

    1994-04-01

    This report documents the objectives, analytical approach, and design of the National Energy Modeling System (NEMS) Renewable Fuels Module (RFM) as it related to the production of the 1994 Annual Energy Outlook (AEO94) forecasts. The report catalogues and describes modeling assumptions, computational methodologies, data inputs, and parameter estimation techniques. A number of offline analyses used in lieu of RFM modeling components are also described. This documentation report serves two purposes. First, it is a reference document for model analysts, model users, and the public interested in the construction and application of the RFM. Second, it meets the legal requirement of the Energy Information Administration (EIA) to provide adequate documentation in support of its models. The RFM consists of six analytical submodules that represent each of the major renewable energy resources -- wood, municipal solid waste (MSW), solar energy, wind energy, geothermal energy, and alcohol fuels. Of these six, four are documented in the following chapters: municipal solid waste, wind, solar and biofuels. Geothermal and wood are not currently working components of NEMS. The purpose of the RFM is to define the technological and cost characteristics of renewable energy technologies, and to pass these characteristics to other NEMS modules for the determination of mid-term forecasted renewable energy demand.

  20. Elementary kinetic modelling applied to solid oxide fuel cell pattern anodes and a direct flame fuel cell system

    Energy Technology Data Exchange (ETDEWEB)

    Vogler, Marcel

    2009-05-27

    In the course of this thesis a model for the prediction of polarisation characteristics of solid oxide fuel cells (SOFC) was developed. The model is based on an elementary kinetic description of electrochemical reactions and the fundamental conservation principles of mass and energy. The model allows to predict the current-voltage relation of an SOFC and offers ideal possibilities for model validation. The aim of this thesis is the identification of rate-limiting processes and the determination of the elementary pathway during charge transfer. The numerical simulation of experiments with model anodes allowed to identify a hydrogen transfer to be the most probable charge-transfer reaction and revealed the influence of diffusive transport. Applying the hydrogen oxidation kinetics to the direct flame fuel cell system (DFFC) showed that electrochemical oxidation of CO is possible based on the same mechanism. Based on the quantification of loss processes in the DFFC system, improvements on cell design, predicting 80% increase of efficiency, were proposed. (orig.)

  1. BEAM 1.7: development for modelling fuel element and bundle buckling strength

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, G.; Xu, S.; Xu, Z.; Paul, U.K. [Atomic Energy of Canada, Mississauga, Ontario (Canada)

    2010-07-01

    This paper describes BEAM, an AECL developed computer program, used to assess mechanical integrity of CANDU fuel bundles. The BEAM code has been developed to satisfy the need for buckling strength analysis of fuel bundles. Buckling refers to the phenomenon where a compressive axial load is large enough that a small lateral load can cause large lateral deflections. The buckling strength refers to the critical compressive axial load at which lateral instability is reached. The buckling strength analysis has practical significance for the design of fuel bundles, where the buckling strength of a fuel element/bundle is assessed so that the conditions leading to bundle jamming in the pressure tube are excluded. This paper presents the development and qualification of the BEAM code, with emphasis on the theoretical background and code implementation of the newly developed fuel element/bundle buckling strength model. (author)

  2. Integrated modeling for optimized regional transportation with compressed natural gas fuel

    Directory of Open Access Journals (Sweden)

    Hossam A. Gabbar

    2016-03-01

    Full Text Available Transportation represents major energy consumption where fuel is considered as a primary energy source. Recent development in the vehicle technology revealed possible economical improvements when using natural gas as a fuel source instead of traditional gasoline. There are several fuel alternatives such as electricity, which showed potential for future long-term transportation. However, the move from current situation where gasoline vehicle is dominating shows high cost compared to compressed natural gas vehicle. This paper presents modeling and simulation methodology to optimize performance of transportation based on quantitative study of the risk-based performance of regional transportation. Emission estimation method is demonstrated and used to optimize transportation strategies based on life cycle costing. Different fuel supply scenarios are synthesized and evaluated, which showed strategic use of natural gas as a fuel supply.

  3. A distributed real-time model of degradation in a solid oxide fuel cell, part II: Analysis of fuel cell performance and potential failures

    Science.gov (United States)

    Zaccaria, V.; Tucker, D.; Traverso, A.

    2016-09-01

    Solid oxide fuel cells are characterized by very high efficiency, low emissions level, and large fuel flexibility. Unfortunately, their elevated costs and relatively short lifetimes reduce the economic feasibility of these technologies at the present time. Several mechanisms contribute to degrade fuel cell performance during time, and the study of these degradation modes and potential mitigation actions is critical to ensure the durability of the fuel cell and their long-term stability. In this work, localized degradation of a solid oxide fuel cell is modeled in real-time and its effects on various cell parameters are analyzed. Profile distributions of overpotential, temperature, heat generation, and temperature gradients in the stack are investigated during degradation. Several causes of failure could occur in the fuel cell if no proper control actions are applied. A local analysis of critical parameters conducted shows where the issues are and how they could be mitigated in order to extend the life of the cell.

  4. Importance of fossil fuel emission uncertainties over Europe for CO2 modeling: model intercomparison

    Directory of Open Access Journals (Sweden)

    F. Delage

    2011-07-01

    Full Text Available Inverse modeling techniques used to quantify surface carbon fluxes commonly assume that the uncertainty of fossil fuel CO2 (FFCO2 emissions is negligible and that intra-annual variations can be neglected. To investigate these assumptions, we analyzed the differences between four fossil fuel emission inventories with spatial and temporal differences over Europe and their impact on the model simulated CO2 concentration. Large temporal flux variations characterize the hourly fields (~40 % and ~80 % for the seasonal and diurnal cycles, peak-to-peak and annual country totals differ by 10 % on average and up to 40 % for some countries (i.e., the Netherlands. These emissions have been prescribed to seven different transport models, resulting in 28 different FFCO2 concentrations fields. The modeled FFCO2 concentration time series at surface sites using time-varying emissions show larger seasonal cycles (+2 ppm at the Hungarian tall tower (HUN and smaller diurnal cycles in summer (−1 ppm at HUN than when using constant emissions. The concentration range spanned by all simulations varies between stations, and is generally larger in winter (up to ~10 ppm peak-to-peak at HUN than in summer (~5 ppm. The contribution of transport model differences to the simulated concentration std-dev is 2–3 times larger than the contribution of emission differences only, at typical European sites used in global inversions. These contributions to the hourly (monthly std-dev's amount to ~1.2 (0.8 ppm and ~0.4 (0.3 ppm for transport and emissions, respectively. First comparisons of the modeled concentrations with 14C-based fossil fuel CO2 observations show that the large transport differences still hamper a quantitative evaluation/validation of the emission inventories. Changes in the estimated monthly biosphere flux (Fbio over Europe, using two inverse modeling approaches, are relatively small (less that 5 % while changes in annual Fbio (up to ~0.15 % GtC yr−1 are only

  5. Model evaluation of faecal contamination in coastal areas affected by urban rivers receiving combined sewer overflows.

    Science.gov (United States)

    Shibata, T; Kojima, K; Lee, S A; Furumai, H

    2014-01-01

    Odaiba seaside park is one of the most popular waterfronts in Tokyo Bay, but is easily affected by wet weather pollutant loads through combined sewer overflows (CSOs). The monitoring data of Escherichia coli clearly showed high faecal contamination after a rainfall event on 9-11 November 2007. We estimated the amounts of discharge volume and E. coli pollutant loads of urban rivers receiving CSO from rainfall chambers as well as pumping stations and primary effluent discharge. The result suggested that Sumida River and Meguro River were more influential to the Odaiba coastal area than other sources including the nearest wastewater treatment plant. Subsequently, we simulated the dynamic behaviour of E. coli by a three-dimensional (3D) hydro-dynamic and water quality model. The model simulation reproduced that E. coli concentration after the rainfall event increased rapidly at first and later gradually decreased. The simulations with and without inflow pollutant loads from urban rivers suggested that the E. coli concentration can be influenced by the Meguro River just after the rainfall event and Sumida River about 1 week later. From the spatial and temporal distribution of surface E. coli concentration, after at least 6 days from the rainfall event, high faecal contamination spread to the whole of the coastal area.

  6. A computational technique to identify the optimal stiffness matrix for a discrete nuclear fuel assembly model

    Energy Technology Data Exchange (ETDEWEB)

    Park, Nam-Gyu, E-mail: nkpark@knfc.co.kr [R and D Center, KEPCO Nuclear Fuel Co., LTD., 493 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, Kyoung-Joo, E-mail: kyoungjoo@knfc.co.kr [R and D Center, KEPCO Nuclear Fuel Co., LTD., 493 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Kim, Kyoung-Hong, E-mail: kyounghong@knfc.co.kr [R and D Center, KEPCO Nuclear Fuel Co., LTD., 493 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Suh, Jung-Min, E-mail: jmsuh@knfc.co.kr [R and D Center, KEPCO Nuclear Fuel Co., LTD., 493 Deokjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2013-02-15

    Highlights: ► An identification method of the optimal stiffness matrix for a fuel assembly structure is discussed. ► The least squares optimization method is introduced, and a closed form solution of the problem is derived. ► The method can be expanded to the system with the limited number of modes. ► Identification error due to the perturbed mode shape matrix is analyzed. ► Verification examples show that the proposed procedure leads to a reliable solution. -- Abstract: A reactor core structural model which is used to evaluate the structural integrity of the core contains nuclear fuel assembly models. Since the reactor core consists of many nuclear fuel assemblies, the use of a refined fuel assembly model leads to a considerable amount of computing time for performing nonlinear analyses such as the prediction of seismic induced vibration behaviors. The computational time could be reduced by replacing the detailed fuel assembly model with a simplified model that has fewer degrees of freedom, but the dynamic characteristics of the detailed model must be maintained in the simplified model. Such a model based on an optimal design method is proposed in this paper. That is, when a mass matrix and a mode shape matrix are given, the optimal stiffness matrix of a discrete fuel assembly model can be estimated by applying the least squares minimization method. The verification of the method is completed by comparing test results and simulation results. This paper shows that the simplified model's dynamic behaviors are quite similar to experimental results and that the suggested method is suitable for identifying reliable mathematical model for fuel assemblies.

  7. Modelling of the Gadolinium Fuel Test IFA-681 using the BISON Code

    Energy Technology Data Exchange (ETDEWEB)

    Pastore, Giovanni [Idaho National Laboratory; Hales, Jason Dean [Idaho National Laboratory; Novascone, Stephen Rhead [Idaho National Laboratory; Spencer, Benjamin Whiting [Idaho National Laboratory; Williamson, Richard L [Idaho National Laboratory

    2016-05-01

    In this work, application of Idaho National Laboratory’s fuel performance code BISON to modelling of fuel rods from the Halden IFA-681 gadolinium fuel test is presented. First, an overview is given of BISON models, focusing on UO2/UO2-Gd2O3 fuel and Zircaloy cladding. Then, BISON analyses of selected fuel rods from the IFA-681 test are performed. For the first time in a BISON application to integral fuel rod simulations, the analysis is informed by detailed neutronics calculations in order to accurately capture the radial power profile throughout the fuel, which is strongly affected by the complex evolution of absorber Gd isotopes. In particular, radial power profiles calculated at IFE–Halden Reactor Project with the HELIOS code are used. The work has been carried out in the frame of the collaboration between Idaho National Laboratory and Halden Reactor Project. Some slide have been added as an Appendix to present the newly developed PolyPole-1 algorithm for modeling of intra-granular fission gas release.

  8. Numerical modeling of oxides of nitrogen based on density of biodiesel fuels

    Directory of Open Access Journals (Sweden)

    A. Gopinath, Sukumar Puhan, G. Nagarajan

    2010-03-01

    Full Text Available Biodiesel is an alternative fuel derived from vegetable oils or animal fats. Research has shown that biodiesel fueled engines produce lesser carbon monoxide, unburned hydrocarbon, and particulate emissions compared to mineral based diesel fuel but emit higher oxides of nitrogen (NOx emissions. NOx could be strongly correlated with density or cetane number of a fuel. The objective of the present work is to predict the NOx concentration of a neat biodiesel fueled compression ignition engine from the density of biodiesel fuels using regression model. Experiments were conducted at different engine loads and the results were given as inputs to develop the regression model. A single cylinder, four stroke, constant speed, air cooled, direct injection diesel engine was used for the experiments. Five different biodiesel fuels were used and NOx were measured at different engine loads. The NOx concentration was taken as response (dependent variable and the density values were taken as explanatory (independent variables. The regression model has yielded R2 values between 0.918 and 0.995. The maximum prediction error was found to be 3.01 %.

  9. Constructing COMSOL Models of a Bacteriological Fuel Cell

    Science.gov (United States)

    Coker, Robert; Mansell, James

    2012-01-01

    We show very initial work on a specific bioelectrochemical system (BES), a bacteriologically driven 'fuel cell' (BFS), that is intended to process waste products, such as CO2 and brine. (1) Processing is the priority, not power generation (2) Really a Microbial Electrolysis Cell (MEC)

  10. Modelling of radiation field around spent fuel container

    NARCIS (Netherlands)

    Kryuchkov, EF; Opalovsky, VA; Tikhomirov, GV

    2005-01-01

    Operation of nuclear reactors leads to the production of spent nuclear fuel (SNF). There are two basic strategies of SNF management: ultimate disposal of SNF in geological formations and recycle or repeated utilisation of reprocessed SNF. In both options, there is an urgent necessity to study radiat

  11. Nuclear fuel cycle system simulation tool based on high-fidelity component modeling

    Energy Technology Data Exchange (ETDEWEB)

    Ames, David E.,

    2014-02-01

    The DOE is currently directing extensive research into developing fuel cycle technologies that will enable the safe, secure, economic, and sustainable expansion of nuclear energy. The task is formidable considering the numerous fuel cycle options, the large dynamic systems that each represent, and the necessity to accurately predict their behavior. The path to successfully develop and implement an advanced fuel cycle is highly dependent on the modeling capabilities and simulation tools available for performing useful relevant analysis to assist stakeholders in decision making. Therefore a high-fidelity fuel cycle simulation tool that performs system analysis, including uncertainty quantification and optimization was developed. The resulting simulator also includes the capability to calculate environmental impact measures for individual components and the system. An integrated system method and analysis approach that provides consistent and comprehensive evaluations of advanced fuel cycles was developed. A general approach was utilized allowing for the system to be modified in order to provide analysis for other systems with similar attributes. By utilizing this approach, the framework for simulating many different fuel cycle options is provided. Two example fuel cycle configurations were developed to take advantage of used fuel recycling and transmutation capabilities in waste management scenarios leading to minimized waste inventories.

  12. Experimental investigation and modeling of an aircraft Otto engine operating with gasoline and heavier fuels

    Science.gov (United States)

    Saldivar Olague, Jose

    A Continental "O-200" aircraft Otto-cycle engine has been modified to burn diesel fuel. Algebraic models of the different processes of the cycle were developed from basic principles applied to a real engine, and utilized in an algorithm for the simulation of engine performance. The simulation provides a means to investigate the performance of the modified version of the Continental engine for a wide range of operating parameters. The main goals of this study are to increase the range of a particular aircraft by reducing the specific fuel consumption of the engine, and to show that such an engine can burn heavier fuels (such as diesel, kerosene, and jet fuel) instead of gasoline. Such heavier fuels are much less flammable during handling operations making them safer than aviation gasoline and very attractive for use in flight operations from naval vessels. The cycle uses an electric spark to ignite the heavier fuel at low to moderate compression ratios, The stratified charge combustion process is utilized in a pre-chamber where the spray injection of the fuel occurs at a moderate pressure of 1200 psi (8.3 MPa). One advantage of fuel injection into the combustion chamber instead of into the intake port, is that the air-to-fuel ratio can be widely varied---in contrast to the narrower limits of the premixed combustion case used in gasoline engines---in order to obtain very lean combustion. Another benefit is that higher compression ratios can be attained in the modified cycle with heavier fuels. The combination of injection into the chamber for lean combustion, and higher compression ratios allow to limit the peak pressure in the cylinder, and to avoid engine damage. Such high-compression ratios are characteristic of Diesel engines and lead to increase in thermal efficiency without pre-ignition problems. In this experimental investigation, operations with diesel fuel have shown that considerable improvements in the fuel efficiency are possible. The results of

  13. Nonlinear modelling of polymer electrolyte membrane fuel cell stack using nonlinear cancellation technique

    Energy Technology Data Exchange (ETDEWEB)

    Barus, R. P. P., E-mail: rismawan.ppb@gmail.com [Engineering Physics, Faculty of Industrial Technology, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung and Centre for Material and Technical Product, Jalan Sangkuriang No. 14 Bandung (Indonesia); Tjokronegoro, H. A.; Leksono, E. [Engineering Physics, Faculty of Industrial Technology, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung (Indonesia); Ismunandar [Chemistry Study, Faculty of Mathematics and Science, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung (Indonesia)

    2014-09-25

    Fuel cells are promising new energy conversion devices that are friendly to the environment. A set of control systems are required in order to operate a fuel cell based power plant system optimally. For the purpose of control system design, an accurate fuel cell stack model in describing the dynamics of the real system is needed. Currently, linear model are widely used for fuel cell stack control purposes, but it has limitations in narrow operation range. While nonlinear models lead to nonlinear control implemnetation whos more complex and hard computing. In this research, nonlinear cancellation technique will be used to transform a nonlinear model into a linear form while maintaining the nonlinear characteristics. The transformation is done by replacing the input of the original model by a certain virtual input that has nonlinear relationship with the original input. Then the equality of the two models is tested by running a series of simulation. Input variation of H2, O2 and H2O as well as disturbance input I (current load) are studied by simulation. The error of comparison between the proposed model and the original nonlinear model are less than 1 %. Thus we can conclude that nonlinear cancellation technique can be used to represent fuel cell nonlinear model in a simple linear form while maintaining the nonlinear characteristics and therefore retain the wide operation range.

  14. Models for solid oxide fuel cell systems exploitation of models hierarchy for industrial design of control and diagnosis strategies

    CERN Document Server

    Marra, Dario; Polverino, Pierpaolo; Sorrentino, Marco

    2016-01-01

    This book presents methodologies for optimal design of control and diagnosis strategies for Solid Oxide Fuel Cell systems. A key feature of the methodologies presented is the exploitation of modelling tools that balance accuracy and computational burden.

  15. Preliminary Thermal Hydraulic Analyses of the Conceptual Core Models with Tubular Type Fuel Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Chae, Hee Taek; Park, Jong Hark; Park, Cheol

    2006-11-15

    A new research reactor (AHR, Advanced HANARO Reactor) based on the HANARO has being conceptually developed for the future needs of research reactors. A tubular type fuel was considered as one of the fuel options of the AHR. A tubular type fuel assembly has several curved fuel plates arranged with a constant small gap to build up cooling channels, which is very similar to an annulus pipe with many layers. This report presents the preliminary analysis of thermal hydraulic characteristics and safety margins for three conceptual core models using tubular fuel assemblies. Four design criteria, which are the fuel temperature, ONB (Onset of Nucleate Boiling) margin, minimum DNBR (Departure from Nucleate Boiling Ratio) and OFIR (Onset of Flow Instability Ratio), were investigated along with various core flow velocities in the normal operating conditions. And the primary coolant flow rate based a conceptual core model was suggested as a design information for the process design of the primary cooling system. The computational fluid dynamics analysis was also carried out to evaluate the coolant velocity distributions between tubular channels and the pressure drop characteristics of the tubular fuel assembly.

  16. Final Report for NFE-07-00912: Development of Model Fuels Experimental Engine Data Base & Kinetic Modeling Parameter Sets

    Energy Technology Data Exchange (ETDEWEB)

    Bunting, Bruce G [ORNL

    2012-10-01

    The automotive and engine industries are in a period of very rapid change being driven by new emission standards, new types of after treatment, new combustion strategies, the introduction of new fuels, and drive for increased fuel economy and efficiency. The rapid pace of these changes has put more pressure on the need for modeling of engine combustion and performance, in order to shorten product design and introduction cycles. New combustion strategies include homogeneous charge compression ignition (HCCI), partial-premixed combustion compression ignition (PCCI), and dilute low temperature combustion which are being developed for lower emissions and improved fuel economy. New fuels include bio-fuels such as ethanol or bio-diesel, drop-in bio-derived fuels and those derived from new crude oil sources such as gas-to-liquids, coal-to-liquids, oil sands, oil shale, and wet natural gas. Kinetic modeling of the combustion process for these new combustion regimes and fuels is necessary in order to allow modeling and performance assessment for engine design purposes. In this research covered by this CRADA, ORNL developed and supplied experimental data related to engine performance with new fuels and new combustion strategies along with interpretation and analysis of such data and consulting to Reaction Design, Inc. (RD). RD performed additional analysis of this data in order to extract important parameters and to confirm engine and kinetic models. The data generated was generally published to make it available to the engine and automotive design communities and also to the Reaction Design Model Fuels Consortium (MFC).

  17. GPS satellite and receiver instrumental biases estimation using least squares method for accurate ionosphere modelling

    Indian Academy of Sciences (India)

    G Sasibhushana Rao

    2007-10-01

    The positional accuracy of the Global Positioning System (GPS)is limited due to several error sources.The major error is ionosphere.By augmenting the GPS,the Category I (CAT I)Precision Approach (PA)requirements can be achieved.The Space-Based Augmentation System (SBAS)in India is known as GPS Aided Geo Augmented Navigation (GAGAN).One of the prominent errors in GAGAN that limits the positional accuracy is instrumental biases.Calibration of these biases is particularly important in achieving the CAT I PA landings.In this paper,a new algorithm is proposed to estimate the instrumental biases by modelling the TEC using 4th order polynomial.The algorithm uses values corresponding to a single station for one month period and the results confirm the validity of the algorithm.The experimental results indicate that the estimation precision of the satellite-plus-receiver instrumental bias is of the order of ± 0.17 nsec.The observed mean bias error is of the order − 3.638 nsec and − 4.71 nsec for satellite 1 and 31 respectively.It is found that results are consistent over the period.

  18. Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen

    2008-01-01

    This work presents the development of an equivalent circuit model of a 65 cell high temperature PEM (HTPEM) fuel cell stack using Electrochemical Impedance Spectroscopy (EIS). The HTPEM fuel cell membranes used are PBI-based and uses phosphoric acid as proton conductor. The operating temperature...... of the MEA's is 160-180oC, depending on the purity of the hydrogen used, the load pattern and the desired lifetime. The advantages of the HTPEM fuel cell technology include fast response to load changes and high tolerance to CO (1-3%)...

  19. Effects of signal light on the fuel consumption and emissions under car-following model

    Science.gov (United States)

    Tang, Tie-Qiao; Yi, Zhi-Yan; Lin, Qing-Feng

    2017-03-01

    In this paper, a car-following model is utilized to study the effects of signal light on each vehicle's fuel consumption, CO, HC and NOX. The numerical results show that each vehicle's fuel consumption and emissions are influenced by the signal light and that the effects are related to the green split of the signal light and the vehicle's time headway at the origin, which can help drivers adjust their micro driving behavior on the road with a signal light to reduce their fuel consumption and emissions.

  20. Modeling and Design of Hybrid PEM Fuel Cell Systems for Lift Trucks

    DEFF Research Database (Denmark)

    Hosseinzadeh, Elham

    . The most common type of fuel cell used for automotive applications is the PEM fuel cell. They are known for their high efficiency, low emissions and high reliability. However, the biggest obstacles to introducing fuel cell vehicles are the lack of a hydrogen infrastructure, cost and durability of the stack....... This model can be used as a guideline for optimal PEMFC operation with respect to electrical efficiency and net power production. In addition to the optimal operation, investigation of different coolants and operating conditions provides some recommendations for water and thermal management of the system...

  1. Ultrasonic inspection of rocket fuel model using laminated transducer and multi-channel step pulser

    Science.gov (United States)

    Mihara, T.; Hamajima, T.; Tashiro, H.; Sato, A.

    2013-01-01

    For the ultrasonic inspection for the packing of solid fuel in a rocket booster, an industrial inspection is difficult. Because the signal to noise ratio in ultrasonic inspection of rocket fuel become worse due to the large attenuation even using lower frequency ultrasound. For the improvement of this problem, we tried to applied the two techniques in ultrasonic inspection, one was the step function pulser system with the super wideband frequency properties and the other was the laminated element transducer. By combining these two techniques, we developed the new ultrasonic measurement system and demonstrated the advantages in ultrasonic inspection of rocket fuel model specimen.

  2. Artificial neural network modeling for fission gas release in LWR UO 2 fuel under RIA conditions

    Science.gov (United States)

    Koo, Yang-Hyun; Oh, Jae-Yong; Lee, Byung-Ho; Tahk, Young-Wook; Song, Kun-Woo

    2010-10-01

    A fission gas release (FGR) model was developed by using an artificial neural network method to predict fission gas release in UO 2 fuel under reactivity initiated accident (RIA) conditions. Based on the test data obtained in the CABRI test reactor and nuclear safety research reactor, the model takes into account the effect of the five parameters: pellet average burnup, peak fuel enthalpy, the ratio of peak fuel enthalpy to pulse width, fission gas release during base-irradiation, and grain size of a fuel pellet. The parametric study of the model, producing a physically reasonable trend of FGR for each parameter, shows that the pellet average burnup and the ratio of peak fuel enthalpy to pulse width are two of the most important parameters. Depending on the combination of input values for the five parameters, the application of the model to a fuel rod under typical RIA conditions of light water reactor produces 1.7-14.0% of FGR for the pellet average burnup ranging from 20 to 70 MW d/kg U.

  3. Rate Theory Modeling and Simulations of Silicide Fuel at LWR Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Yinbin [Argonne National Lab. (ANL), Argonne, IL (United States); Ye, Bei [Argonne National Lab. (ANL), Argonne, IL (United States); Mei, Zhigang [Argonne National Lab. (ANL), Argonne, IL (United States); Hofman, Gerard [Argonne National Lab. (ANL), Argonne, IL (United States); Yacout, Abdellatif [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-12-10

    Uranium silicide (U3Si2) fuel has higher thermal conductivity and higher uranium density, making it a promising candidate for the accident-tolerant fuel (ATF) used in light water reactors (LWRs). However, previous studies on the fuel performance of U3Si2, including both experimental and computational approaches, have been focusing on the irradiation conditions in research reactors, which usually involve low operation temperatures and high fuel burnups. Thus, it is important to examine the fuel performance of U3Si2 at typical LWR conditions so as to evaluate the feasibility of replacing conventional uranium dioxide fuel with this silicide fuel material. As in-reactor irradiation experiments involve significant time and financial cost, it is appropriate to utilize modeling tools to estimate the behavior of U3Si2 in LWRs based on all those available research reactor experimental references and state-of-the-art density functional theory (DFT) calculation capabilities at the early development stage. Hence, in this report, a comprehensive investigation of the fission gas swelling behavior of U3Si2 at LWR conditions is introduced. The modeling efforts mentioned in this report was based on the rate theory (RT) model of fission gas bubble evolution that has been successfully applied for a variety of fuel materials at devious reactor conditions. Both existing experimental data and DFT-calculated results were used for the optimization of the parameters adopted by the RT model. Meanwhile, the fuel-cladding interaction was captured by the coupling of the RT model with simplified mechanical correlations. Therefore, the swelling behavior of U3Si2 fuel and its consequent interaction with cladding in LWRs was predicted by the rate theory modeling, providing valuable information for the development of U3Si2 fuel as an accident

  4. Dynamic fuel cell stack model for real-time simulation based on system identification

    Energy Technology Data Exchange (ETDEWEB)

    Meiler, M.; Schmid, O.; Schudy, M. [Department of MEA and Stack Technology, DaimlerChrysler AG, Neue Str. 95, D-73230 Kirchheim/Teck (Germany); Hofer, E.P. [Department of Measurement, Control and Microtechnology, University of Ulm, Albert-Einstein-Allee 41, D-89081 Ulm (Germany)

    2008-02-01

    The authors have been developing an empirical mathematical model to predict the dynamic behaviour of a polymer electrolyte membrane fuel cell (PEMFC) stack. Today there is a great number of models, describing steady-state behaviour of fuel cells by estimating the equilibrium voltage for a certain set of operating parameters, but models capable of predicting the transient process between two steady-state points are rare. However, in automotive applications round about 80% of operating situations are dynamic. To improve the reliability of fuel cell systems by model-based control for real-time simulation dynamic fuel cell stack model is needed. Physical motivated models, described by differential equations, usually are complex and need a lot of computing time. To meet the real-time capability the focus is set on empirical models. Fuel cells are highly nonlinear systems, so often used auto-regressive (AR), output-error (OE) or Box-Jenkins (BJ) models do not accomplish satisfying accuracy. Best results are achieved by splitting the behaviour into a nonlinear static and a linear dynamic subsystem, a so-called Uryson-Model. For system identification and model validation load steps with different amplitudes are applied to the fuel cell stack at various operation points and the voltage response is recorded. The presented model is implemented in MATLAB environment and has a computing time of less than 1 ms per step on a standard desktop computer with a 2.8 MHz CPU and 504 MB RAM. Lab tests are carried out at DaimlerChrysler R and D Centre with DaimlerChrysler PEMFC hardware and a good agreement is found between model simulations and lab tests. (author)

  5. Dynamic fuel cell stack model for real-time simulation based on system identification

    Science.gov (United States)

    Meiler, M.; Schmid, O.; Schudy, M.; Hofer, E. P.

    The authors have been developing an empirical mathematical model to predict the dynamic behaviour of a polymer electrolyte membrane fuel cell (PEMFC) stack. Today there is a great number of models, describing steady-state behaviour of fuel cells by estimating the equilibrium voltage for a certain set of operating parameters, but models capable of predicting the transient process between two steady-state points are rare. However, in automotive applications round about 80% of operating situations are dynamic. To improve the reliability of fuel cell systems by model-based control for real-time simulation dynamic fuel cell stack model is needed. Physical motivated models, described by differential equations, usually are complex and need a lot of computing time. To meet the real-time capability the focus is set on empirical models. Fuel cells are highly nonlinear systems, so often used auto-regressive (AR), output-error (OE) or Box-Jenkins (BJ) models do not accomplish satisfying accuracy. Best results are achieved by splitting the behaviour into a nonlinear static and a linear dynamic subsystem, a so-called Uryson-Model. For system identification and model validation load steps with different amplitudes are applied to the fuel cell stack at various operation points and the voltage response is recorded. The presented model is implemented in MATLAB environment and has a computing time of less than 1 ms per step on a standard desktop computer with a 2.8 MHz CPU and 504 MB RAM. Lab tests are carried out at DaimlerChrysler R&D Centre with DaimlerChrysler PEMFC hardware and a good agreement is found between model simulations and lab tests.

  6. Design and modeling of power system for a fuel cell hybrid switcher locomotive

    Energy Technology Data Exchange (ETDEWEB)

    Guo Liping, E-mail: lguo@niu.ed [Department of Engineering Technology, Northern Illinois University, DeKalb, IL 60115 (United States); Yedavalli, Karthik; Zinger, Donald [Department of Electrical Engineering, Northern Illinois University, DeKalb, IL 60115 (United States)

    2011-02-15

    This paper discusses the design and modeling of power system for a fuel cell hybrid locomotive. Different types of fuel cells for appropriate application to locomotives were compared, fuel cell and auxiliary storage devices were modeled, and a control strategy for the overall system was developed in this paper. By using the proposed control strategy, the power control system regulates the sharing of power demand between fuel cell and auxiliary storage units including batteries and ultracapacitors. Experimental data of the power duty cycle of a typical switcher locomotive is analyzed. The proposed control system is tested using the experimental data. Results show that the control system is able to maintain output voltage from different power sources within a certain range, keep the state of charge of the batteries within an optimal range and meet power demand of the locomotive at a high efficiency.

  7. Design and modeling of power system for a fuel cell hybrid switcher locomotive

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Liping [Department of Engineering Technology, Northern Illinois University, DeKalb, IL 60115 (United States); Yedavalli, Karthik; Zinger, Donald [Department of Electrical Engineering, Northern Illinois University, DeKalb, IL 60115 (United States)

    2011-02-15

    This paper discusses the design and modeling of power system for a fuel cell hybrid locomotive. Different types of fuel cells for appropriate application to locomotives were compared, fuel cell and auxiliary storage devices were modeled, and a control strategy for the overall system was developed in this paper. By using the proposed control strategy, the power control system regulates the sharing of power demand between fuel cell and auxiliary storage units including batteries and ultracapacitors. Experimental data of the power duty cycle of a typical switcher locomotive is analyzed. The proposed control system is tested using the experimental data. Results show that the control system is able to maintain output voltage from different power sources within a certain range, keep the state of charge of the batteries within an optimal range and meet power demand of the locomotive at a high efficiency. (author)

  8. Development of numerical models for Monte Carlo simulations of Th-Pb fuel assembly

    Directory of Open Access Journals (Sweden)

    Oettingen Mikołaj

    2017-01-01

    Full Text Available The thorium-uranium fuel cycle is a promising alternative against uranium-plutonium fuel cycle, but it demands many advanced research before starting its industrial application in commercial nuclear reactors. The paper presents the development of the thorium-lead (Th-Pb fuel assembly numerical models for the integral irradiation experiments. The Th-Pb assembly consists of a hexagonal array of ThO2 fuel rods and metallic Pb rods. The design of the assembly allows different combinations of rods for various types of irradiations and experimental measurements. The numerical model of the Th-Pb assembly was designed for the numerical simulations with the continuous energy Monte Carlo Burnup code (MCB implemented on the supercomputer Prometheus of the Academic Computer Centre Cyfronet AGH.

  9. A model for release of fission products from a breached fuel plate under wet storage

    Energy Technology Data Exchange (ETDEWEB)

    Terremoto, L.A.A.; Seerban, R.S.; Zeituni, C.A.; Silva, J.E.R. da; Silva, A.T. e; Castanheira, M.; Lucki, G.; Damy, M. de A.; Teodoro, C.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mail: laaterre@ipen.br

    2007-07-01

    MTR fuel elements burned-up inside the core of nuclear research reactors are stored worldwide mainly under the water of storage pools. When cladding breach is present in one or more fuel plates of such elements, radioactive fission products are released into the storage pool water. This work proposes a model to describe the release mechanism considering the diffusion of nuclides of a radioactive fission product either through a postulated small cylindrical breach or directly from a large circular hole in the cladding. In each case, an analytical expression is obtained for the activity released into the water as a function of the total storage time of a breached fuel plate. Regarding sipping tests already performed at the IEA-R1 research reactor on breached MTR fuel elements, the proposed model correlates successfully the specific activity of {sup 137}Cs, measured as a function of time, with the evaluated size of the cladding breach. (author)

  10. A review on the performance and modelling of proton exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Boucetta, A., E-mail: abirboucetta@yahoo.fr; Ghodbane, H., E-mail: h.ghodbane@mselab.org; Bahri, M., E-mail: m.bahri@mselab.org [Department of Electrical Engineering, MSE Laboratory, Mohamed khider Biskra University (Algeria); Ayad, M. Y., E-mail: ayadmy@gmail.com [R& D, Industrial Hybrid Vehicle Applications (France)

    2016-07-25

    Proton Exchange Membrane Fuel Cells (PEMFC), are energy efficient and environmentally friendly alternative to conventional energy conversion for various applications in stationary power plants, portable power device and transportation. PEM fuel cells provide low operating temperature and high-energy efficiency with near zero emission. A PEM fuel cell is a multiple distinct parts device and a series of mass, energy, transport through gas channels, electric current transport through membrane electrode assembly and electrochemical reactions at the triple-phase boundaries. These processes play a decisive role in determining the performance of the Fuel cell, so that studies on the phenomena of gas flows and the performance modelling are made deeply. This paper gives a comprehensive overview of the state of the art on the Study of the phenomena of gas flow and performance modelling of PEMFC.

  11. A review on the performance and modelling of proton exchange membrane fuel cells

    Science.gov (United States)

    Boucetta, A.; Ghodbane, H.; Ayad, M. Y.; Bahri, M.

    2016-07-01

    Proton Exchange Membrane Fuel Cells (PEMFC), are energy efficient and environmentally friendly alternative to conventional energy conversion for various applications in stationary power plants, portable power device and transportation. PEM fuel cells provide low operating temperature and high-energy efficiency with near zero emission. A PEM fuel cell is a multiple distinct parts device and a series of mass, energy, transport through gas channels, electric current transport through membrane electrode assembly and electrochemical reactions at the triple-phase boundaries. These processes play a decisive role in determining the performance of the Fuel cell, so that studies on the phenomena of gas flows and the performance modelling are made deeply. This paper gives a comprehensive overview of the state of the art on the Study of the phenomena of gas flow and performance modelling of PEMFC.

  12. Treating asphericity in fuel particle pressure vessel modeling

    Science.gov (United States)

    Miller, Gregory K.; Wadsworth, Derek C.

    1994-07-01

    The prototypical nuclear fuel of the New Production Modular High Temperature Gas-Cooled Reactor (NP-MHTGR) consists of spherical TRISO-coated particles suspended in graphite cylinders. The coating layers surrounding the fuel kernels in these particles consist of pyrolytic carbon layers and a silicon carbide layer. These coating layers act as a pressure vessel which retains fission product gases. In the operating conditions of the NP-MHTGR, a small percentage of these particles (pressure vessels) are expected to fail due to the pressure loading. The fuel particles of the NP-MHTGR deviate to some degree from a true spherical shape, which may have some effect on the failure percentages. A method is presented that treats the asphericity of the particles in predicting failure probabilities for particle samples. It utilizes a combination of finite element analysis and Monte Carlo sampling and is based on the Weibull statistical theory. The method is used here to assess the effects of asphericity in particles of two common geometric shapes, i.e. faceted particles and ellipsoidal particles. The method presented could be used to treat particle anomalies other than asphericity.

  13. New approaches to the modelling of multi-component fuel droplet heating and evaporation

    KAUST Repository

    Sazhin, Sergei S

    2015-02-25

    The previously suggested quasi-discrete model for heating and evaporation of complex multi-component hydrocarbon fuel droplets is described. The dependence of density, viscosity, heat capacity and thermal conductivity of liquid components on carbon numbers n and temperatures is taken into account. The effects of temperature gradient and quasi-component diffusion inside droplets are taken into account. The analysis is based on the Effective Thermal Conductivity/Effective Diffusivity (ETC/ED) model. This model is applied to the analysis of Diesel and gasoline fuel droplet heating and evaporation. The components with relatively close n are replaced by quasi-components with properties calculated as average properties of the a priori defined groups of actual components. Thus the analysis of the heating and evaporation of droplets consisting of many components is replaced with the analysis of the heating and evaporation of droplets consisting of relatively few quasi-components. It is demonstrated that for Diesel and gasoline fuel droplets the predictions of the model based on five quasi-components are almost indistinguishable from the predictions of the model based on twenty quasi-components for Diesel fuel droplets and are very close to the predictions of the model based on thirteen quasi-components for gasoline fuel droplets. It is recommended that in the cases of both Diesel and gasoline spray combustion modelling, the analysis of droplet heating and evaporation is based on as little as five quasi-components.

  14. Generation IV benchmarking of TRISO fuel performance models under accident conditions: Modeling input data

    Energy Technology Data Exchange (ETDEWEB)

    Collin, Blaise P. [Idaho National Laboratory (INL), Idaho Falls, ID (United States)

    2014-09-01

    This document presents the benchmark plan for the calculation of particle fuel performance on safety testing experiments that are representative of operational accidental transients. The benchmark is dedicated to the modeling of fission product release under accident conditions by fuel performance codes from around the world, and the subsequent comparison to post-irradiation experiment (PIE) data from the modeled heating tests. The accident condition benchmark is divided into three parts: the modeling of a simplified benchmark problem to assess potential numerical calculation issues at low fission product release; the modeling of the AGR-1 and HFR-EU1bis safety testing experiments; and, the comparison of the AGR-1 and HFR-EU1bis modeling results with PIE data. The simplified benchmark case, thereafter named NCC (Numerical Calculation Case), is derived from ''Case 5'' of the International Atomic Energy Agency (IAEA) Coordinated Research Program (CRP) on coated particle fuel technology [IAEA 2012]. It is included so participants can evaluate their codes at low fission product release. ''Case 5'' of the IAEA CRP-6 showed large code-to-code discrepancies in the release of fission products, which were attributed to ''effects of the numerical calculation method rather than the physical model''[IAEA 2012]. The NCC is therefore intended to check if these numerical effects subsist. The first two steps imply the involvement of the benchmark participants with a modeling effort following the guidelines and recommendations provided by this document. The third step involves the collection of the modeling results by Idaho National Laboratory (INL) and the comparison of these results with the available PIE data. The objective of this document is to provide all necessary input data to model the benchmark cases, and to give some methodology guidelines and recommendations in order to make all results suitable for comparison

  15. Generation IV benchmarking of TRISO fuel performance models under accident conditions: Modeling input data

    Energy Technology Data Exchange (ETDEWEB)

    Collin, Blaise P. [Idaho National Laboratory (INL), Idaho Falls, ID (United States)

    2014-09-01

    This document presents the benchmark plan for the calculation of particle fuel performance on safety testing experiments that are representative of operational accidental transients. The benchmark is dedicated to the modeling of fission product release under accident conditions by fuel performance codes from around the world, and the subsequent comparison to post-irradiation experiment (PIE) data from the modeled heating tests. The accident condition benchmark is divided into three parts: the modeling of a simplified benchmark problem to assess potential numerical calculation issues at low fission product release; the modeling of the AGR-1 and HFR-EU1bis safety testing experiments; and, the comparison of the AGR-1 and HFR-EU1bis modeling results with PIE data. The simplified benchmark case, thereafter named NCC (Numerical Calculation Case), is derived from ''Case 5'' of the International Atomic Energy Agency (IAEA) Coordinated Research Program (CRP) on coated particle fuel technology [IAEA 2012]. It is included so participants can evaluate their codes at low fission product release. ''Case 5'' of the IAEA CRP-6 showed large code-to-code discrepancies in the release of fission products, which were attributed to ''effects of the numerical calculation method rather than the physical model''[IAEA 2012]. The NCC is therefore intended to check if these numerical effects subsist. The first two steps imply the involvement of the benchmark participants with a modeling effort following the guidelines and recommendations provided by this document. The third step involves the collection of the modeling results by Idaho National Laboratory (INL) and the comparison of these results with the available PIE data. The objective of this document is to provide all necessary input data to model the benchmark cases, and to give some methodology guidelines and recommendations in order to make all results suitable for comparison

  16. Bed models for solid fuel conversion process in grate-fired boilers

    DEFF Research Database (Denmark)

    Costa, M.; Massarotti, N.; Indrizzi, V.

    2013-01-01

    to describe the thermo-chemical conversion process of a solid fuel bed in a grate-fired boiler is presented. In this work both models consider the incoming solid fuel as subjected to drying, pyrolysis, gasification and combustion. In the first approach the biomass bed is treated as a 0D system, but the thermo......Because of the complexity to describe and solve thermo-chemical processes occurring in a fuel bed in grate-fired boiler, it is often necessary to simplify the process and use modeling techniques based on overall mass, energy and species conservation. A comparison between two numerical models......-chemical processes are divided in two successive sections: drying and conversion (which includes pyrolysis, gasification and combustion). The second model is an empirical 1D approach. The two models need input data such as composition, temperature and feeding rate of biomass and primary air. Temperature, species...

  17. Control oriented modeling of ejector in anode gas recirculation solid oxygen fuel cell systems

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Yinhai, E-mail: yinhai.zhu@gmail.co [School of Energy and Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Li Yanzhong, E-mail: yzli-epe@mail.xjtu.edu.c [School of Energy and Power Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Cai Wenjian [School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2011-04-15

    A one-equation model is proposed for fuel ejector in anode gas recirculation solid oxide fuel cell (SOFC) system. Firstly, the fundamental governing equations are established by employing the thermodynamic, fluid dynamic principles and chemical constraints inside the ejector; secondly, the one-equation model is derived by using the parameter analysis and lumped-parameter method. Finally, the computational fluid dynamics (CFD) technique is employed to obtain the source data for determining the model parameters. The effectiveness of the model is studied under a wide range of operation conditions. The effect of ejector performance on the anode gas recirculation SOFC system is also discussed. The presented model, which only contains four constant parameters, is useful in real-time control and optimization of fuel ejector in the anode gas recirculation SOFC system.

  18. Modeling and simulation of the anode in direct ethanol fuels cells

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Ruy Jr.; dos Anjos, Daniela Marques [Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, Av. Trabalhador Saocarlense, 400, C. P. 780, 13560-970 Sao Carlos, SP (Brazil); Laboratoire de Catalyse en Chimie Organique, Universite de Poitiers, 40, Av. du Recteur Pineau, 86022 Poitiers (France); Tremiliosi-Filho, Germano; Gonzalez, Ernesto Rafael [Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, Av. Trabalhador Saocarlense, 400, C. P. 780, 13560-970 Sao Carlos, SP (Brazil); Coutanceau, Christophe; Sibert, Eric; Leger, Jean-Michel; Kokoh, Kouakou Boniface [Laboratoire de Catalyse en Chimie Organique, Universite de Poitiers, 40, Av. du Recteur Pineau, 86022 Poitiers (France)

    2008-05-15

    Mathematical modeling has been extensively applied to the study and development of fuel cells. In this work, the objective is to characterize a mechanistic model for the anode of a direct ethanol fuel cell and perform appropriate simulations. The software Comsol Multiphysics {sup registered} (and the Chemical Engineering Module) was used in this work. The software Comsol Multiphysics {sup registered} is an interactive environment for modeling scientific and engineering applications using partial differential equations (PDEs). Based on the finite element method, it provides speed and accuracy for several applications. The mechanistic model developed here can supply details of the physical system, such as the concentration profiles of the components within the anode and the coverage of the adsorbed species on the electrode surface. Also, the anode overpotential-current relationship can be obtained. To validate the anode model presented in this paper, experimental data obtained with a single fuel cell operating with an ethanol solution at the anode were used. (author)

  19. GEN-IV BENCHMARKING OF TRISO FUEL PERFORMANCE MODELS UNDER ACCIDENT CONDITIONS MODELING INPUT DATA

    Energy Technology Data Exchange (ETDEWEB)

    Collin, Blaise Paul [Idaho National Laboratory

    2016-09-01

    This document presents the benchmark plan for the calculation of particle fuel performance on safety testing experiments that are representative of operational accidental transients. The benchmark is dedicated to the modeling of fission product release under accident conditions by fuel performance codes from around the world, and the subsequent comparison to post-irradiation experiment (PIE) data from the modeled heating tests. The accident condition benchmark is divided into three parts: • The modeling of a simplified benchmark problem to assess potential numerical calculation issues at low fission product release. • The modeling of the AGR-1 and HFR-EU1bis safety testing experiments. • The comparison of the AGR-1 and HFR-EU1bis modeling results with PIE data. The simplified benchmark case, thereafter named NCC (Numerical Calculation Case), is derived from “Case 5” of the International Atomic Energy Agency (IAEA) Coordinated Research Program (CRP) on coated particle fuel technology [IAEA 2012]. It is included so participants can evaluate their codes at low fission product release. “Case 5” of the IAEA CRP-6 showed large code-to-code discrepancies in the release of fission products, which were attributed to “effects of the numerical calculation method rather than the physical model” [IAEA 2012]. The NCC is therefore intended to check if these numerical effects subsist. The first two steps imply the involvement of the benchmark participants with a modeling effort following the guidelines and recommendations provided by this document. The third step involves the collection of the modeling results by Idaho National Laboratory (INL) and the comparison of these results with the available PIE data. The objective of this document is to provide all necessary input data to model the benchmark cases, and to give some methodology guidelines and recommendations in order to make all results suitable for comparison with each other. The participants should read

  20. Continuous energy Monte Carlo calculations for randomly distributed spherical fuels based on statistical geometry model

    Energy Technology Data Exchange (ETDEWEB)

    Murata, Isao [Osaka Univ., Suita (Japan); Mori, Takamasa; Nakagawa, Masayuki; Itakura, Hirofumi

    1996-03-01

    The method to calculate neutronics parameters of a core composed of randomly distributed spherical fuels has been developed based on a statistical geometry model with a continuous energy Monte Carlo method. This method was implemented in a general purpose Monte Carlo code MCNP, and a new code MCNP-CFP had been developed. This paper describes the model and method how to use it and the validation results. In the Monte Carlo calculation, the location of a spherical fuel is sampled probabilistically along the particle flight path from the spatial probability distribution of spherical fuels, called nearest neighbor distribution (NND). This sampling method was validated through the following two comparisons: (1) Calculations of inventory of coated fuel particles (CFPs) in a fuel compact by both track length estimator and direct evaluation method, and (2) Criticality calculations for ordered packed geometries. This method was also confined by applying to an analysis of the critical assembly experiment at VHTRC. The method established in the present study is quite unique so as to a probabilistic model of the geometry with a great number of spherical fuels distributed randomly. Realizing the speed-up by vector or parallel computations in future, it is expected to be widely used in calculation of a nuclear reactor core, especially HTGR cores. (author).

  1. Model development for quantitative evaluation of proliferation resistance of nuclear fuel cycles

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Won Il; Kim, Ho Dong; Yang, Myung Seung

    2000-07-01

    This study addresses the quantitative evaluation of the proliferation resistance which is important factor of the alternative nuclear fuel cycle system. In this study, model was developed to quantitatively evaluate the proliferation resistance of the nuclear fuel cycles. The proposed models were then applied to Korean environment as a sample study to provide better references for the determination of future nuclear fuel cycle system in Korea. In order to quantify the proliferation resistance of the nuclear fuel cycle, the proliferation resistance index was defined in imitation of an electrical circuit with an electromotive force and various electrical resistance components. The analysis on the proliferation resistance of nuclear fuel cycles has shown that the resistance index as defined herein can be used as an international measure of the relative risk of the nuclear proliferation if the motivation index is appropriately defined. It has also shown that the proposed model can include political issues as well as technical ones relevant to the proliferation resistance, and consider all facilities and activities in a specific nuclear fuel cycle (from mining to disposal). In addition, sensitivity analyses on the sample study indicate that the direct disposal option in a country with high nuclear propensity may give rise to a high risk of the nuclear proliferation than the reprocessing option in a country with low nuclear propensity.

  2. Construction and utilization of linear empirical core models for PWR in-core fuel management

    Energy Technology Data Exchange (ETDEWEB)

    Okafor, K.C.

    1988-01-01

    An empirical core-model construction procedure for pressurized water reactor (PWR) in-core fuel management is developed that allows determining the optimal BOC k{sub {infinity}} profiles in PWRs as a single linear-programming problem and thus facilitates the overall optimization process for in-core fuel management due to algorithmic simplification and reduction in computation time. The optimal profile is defined as one that maximizes cycle burnup. The model construction scheme treats the fuel-assembly power fractions, burnup, and leakage as state variables and BOC zone enrichments as control variables. The core model consists of linear correlations between the state and control variables that describe fuel-assembly behavior in time and space. These correlations are obtained through time-dependent two-dimensional core simulations. The core model incorporates the effects of composition changes in all the enrichment control zones on a given fuel assembly and is valid at all times during the cycle for a given range of control variables. No assumption is made on the geometry of the control zones. A scatter-composition distribution, as well as annular, can be considered for model construction. The application of the methodology to a typical PWR core indicates good agreement between the model and exact simulation results.

  3. Fuel Efficient Diesel Particulate Filter (DPF) Modeling and Development

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Mark L.; Gallant, Thomas R.; Kim, Do Heui; Maupin, Gary D.; Zelenyuk, Alla

    2010-08-01

    The project described in this report seeks to promote effective diesel particulate filter technology with minimum fuel penalty by enhancing fundamental understanding of filtration mechanisms through targeted experiments and computer simulations. The overall backpressure of a filtration system depends upon complex interactions of particulate matter and ash with the microscopic pores in filter media. Better characterization of these phenomena is essential for exhaust system optimization. The acicular mullite (ACM) diesel particulate filter substrate is under continuing development by Dow Automotive. ACM is made up of long mullite crystals which intersect to form filter wall framework and protrude from the wall surface into the DPF channels. ACM filters have been demonstrated to effectively remove diesel exhaust particles while maintaining relatively low backpressure. Modeling approaches developed for more conventional ceramic filter materials, such as silicon carbide and cordierite, have been difficult to apply to ACM because of properties arising from its unique microstructure. Penetration of soot into the high-porosity region of projecting crystal structures leads to a somewhat extended depth filtration mode, but with less dramatic increases in pressure drop than are normally observed during depth filtration in cordierite or silicon carbide filters. Another consequence is greater contact between the soot and solid surfaces, which may enhance the action of some catalyst coatings in filter regeneration. The projecting crystals appear to provide a two-fold benefit for maintaining low backpressures during filter loading: they help prevent soot from being forced into the throats of pores in the lower porosity region of the filter wall, and they also tend to support the forming filter cake, resulting in lower average cake density and higher permeability. Other simulations suggest that soot deposits may also tend to form at the tips of projecting crystals due to the axial

  4. 3D modeling of missing pellet surface defects in BWR fuel

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, B.W., E-mail: Benjamin.Spencer@inl.gov; Williamson, R.L.; Stafford, D.S.; Novascone, S.R.; Hales, J.D.; Pastore, G.

    2016-10-15

    Highlights: • A global/local analysis procedure for missing pellet surface defects is proposed. • This is applied to defective BWR fuel under blade withdrawal and high power ramp conditions. • Sensitivity of the cladding response to key model parameters is studied. - Abstract: One of the important roles of cladding in light water reactor fuel rods is to prevent the release of fission products. To that end, it is essential that the cladding maintain its integrity under a variety of thermal and mechanical loading conditions. Local geometric irregularities in fuel pellets caused by manufacturing defects known as missing pellet surfaces (MPS) can in some circumstances lead to elevated cladding stresses that are sufficiently high to cause cladding failure. Accurate modeling of these defects can help prevent these types of failures. The BISON nuclear fuel performance code developed at Idaho National Laboratory can be used to simulate the global thermo-mechanical fuel rod behavior, as well as the local response of regions of interest, in either 2D or 3D. In either case, a full set of models to represent the thermal and mechanical properties of the fuel, cladding and plenum gas is employed. A procedure for coupling 2D full-length fuel rod models to detailed 3D models of the region of the rod containing a MPS defect is detailed here. The global and local model each contain appropriate physics and behavior models for nuclear fuel. This procedure is demonstrated on a simulation of a boiling water reactor (BWR) fuel rod containing a pellet with an MPS defect, subjected to a variety of transient events, including a control blade withdrawal and a ramp to high power. The importance of modeling the local defect using a 3D model is highlighted by comparing 3D and 2D representations of the defective pellet region. Parametric studies demonstrate the effects of the choice of gaseous swelling model and of the depth and geometry of the MPS defect on the response of the cladding

  5. Modeling, control and integration of a portable solid oxide fuel cell system

    Science.gov (United States)

    Adhikari, Puran

    This thesis presents an innovative method for the modeling, control and integration of a portable hybrid solid oxide fuel cell system. The control and integration of the fuel cell system is important not only for its efficient operation, but also for issues related to safety and reliability. System modeling is needed in order to facilitate the controller design. Mathematical models of the various components of the system are built in the matlab/simulink environment. Dynamic modeling of the fuel cell stack, catalytic partial oxidation (CPOX) reformer, heat exchanger, tail gas combustor and tail gas splitter of the balance of plant system is performed first. Followed by, modeling of the three input DC/DC converter and energy storage devices (battery and supercapacitor). A two-level control approach, higher level and lower level, is adopted in this research. Each of the two major subsystems, balance of plant subsystem and power electronics subsystem, has its own local level controller (called lower level controller) that are designed such that they follow exactly the command reference from a higher level controller. The higher level controller is an intelligent controller that makes decisions about how the lower level or local controllers should perform based on the status of fuel cell, energy storage device and external load demand. Linear analysis has been done for the design and development of the local controllers as appropriate. For the higher level controller, a finite state machine model is developed and implemented using stateflow and fuzzy logic toolboxes of matlab. Simulations are carried out for the integrated system. The simulation results verify that the controllers are robust in performance during the transient condition when the energy storage devices supplement fuel cells. The temperature and flow rates of the fuel and air are controlled as desired. The output from the designed fuel cell system is a regulated DC voltage, which verifies the overall

  6. Features in geometric receiver shapes modelling bat-like directivity patterns.

    Science.gov (United States)

    Guarato, Francesco; Andrews, Heather; Windmill, James F C; Jackson, Joseph; Pierce, Gareth; Gachagan, Anthony

    2015-09-03

    The directional properties of bat ears as receivers is a current area of interest in ultrasound research. This paper presents a new approach to analyse the relationship between morphological features and acoustical properties of the external ear of bat species. The beam pattern of Rousettus leschenaultii's right ear is measured and compared to that of receiver structures whose design is inspired by the bat ear itself and made of appropriate geometric shapes. The regular shape of these receivers makes it possible to control the key reception parameters and thus to understand the effect on the associated beam pattern of the parameters themselves. Measurements show one receiver structure has a beam pattern very similar to that of R. leschenaultii's ear, thus explaining the function of individual parts constituting its ear. As it is applicable to all bat species, this approach can provide a useful tool to investigate acoustics in bats, and possibly other mammals.

  7. Modeling of a PEM Fuel Cell Stack using Partial Least Squares and Artificial Neural Networks

    Energy Technology Data Exchange (ETDEWEB)

    Han, In-Su; Shin, Hyun Khil [GS Caltex Corp, Daejeon (Korea, Republic of)

    2015-04-15

    We present two data-driven modeling methods, partial least square (PLS) and artificial neural network (ANN), to predict the major operating and performance variables of a polymer electrolyte membrane (PEM) fuel cell stack. PLS and ANN models were constructed using the experimental data obtained from the testing of a 30 kW-class PEM fuel cell stack, and then were compared with each other in terms of their prediction and computational performances. To reduce the complexity of the models, we combined a variables importance on PLS projection (VIP) as a variable selection method into the modeling procedure in which the predictor variables are selected from a set of input operation variables. The modeling results showed that the ANN models outperformed the PLS models in predicting the average cell voltage and cathode outlet temperature of the fuel cell stack. However, the PLS models also offered satisfactory prediction performances although they can only capture linear correlations between the predictor and output variables. Depending on the degree of modeling accuracy and speed, both ANN and PLS models can be employed for performance predictions, offline and online optimizations, controls, and fault diagnoses in the field of PEM fuel cell designs and operations.

  8. Regional refining models for alternative fuels using shale and coal synthetic crudes: identification and evaluation of optimized alternative fuels. Annual report, March 20, 1979-March 19, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Sefer, N.R.; Russell, J.A.

    1980-11-01

    The initial phase has been completed in the project to evaluate alternative fuels for highway transportation from synthetic crudes. Three refinery models were developed for Rocky Mountain, Mid-Continent and Great Lakes regions to make future product volumes and qualities forecast for 1995. Projected quantities of shale oil and coal oil syncrudes were introduced into the raw materials slate. Product slate was then varied from conventional products to evaluate maximum diesel fuel and broadcut fuel in all regions. Gasoline supplement options were evaluated in one region for 10% each of methanol, ethanol, MTBE or synthetic naphtha in the blends along with syncrude components. Compositions and qualities of the fuels were determined for the variation in constraints and conditions established for the study. Effects on raw materials, energy consumption and investment costs were reported. Results provide the basis to formulate fuels for laboratory and engine evaluation in future phases of the project.

  9. On the application of the PFEM to droplet dynamics modeling in fuel cells

    Science.gov (United States)

    Ryzhakov, Pavel B.; Jarauta, Alex; Secanell, Marc; Pons-Prats, Jordi

    2017-07-01

    The Particle Finite Element Method (PFEM) is used to develop a model to study two-phase flow in fuel cell gas channels. First, the PFEM is used to develop the model of free and sessile droplets. The droplet model is then coupled to an Eulerian, fixed-grid, model for the airflow. The resulting coupled PFEM-Eulerian algorithm is used to study droplet oscillations in an air flow and droplet growth in a low-temperature fuel cell gas channel. Numerical results show good agreement with predicted frequencies of oscillation, contact angle, and deformation of injected droplets in gas channels. The PFEM-based approach provides a novel strategy to study droplet dynamics in fuel cells.

  10. An non-uniformity voltage model for proton exchange membrane fuel cell

    Science.gov (United States)

    Li, Kelei; Li, Yankun; Liu, Jiawei; Guo, Ai

    2017-01-01

    The fuel cell used in transportation has environmental protection, high efficiency and no line traction power system which can greatly reduce line construction investment. That makes it a huge potential. The voltage uniformity is one of the most important factors affecting the operation life of proton exchange membrane fuel cell (PEMFC). On the basis of principle and classical model of the PEMFC, single cell voltage is calculated and the location coefficients are introduced so as to establish a non-uniformity voltage model. These coefficients are estimated with the experimental datum at stack current 50 A. The model is validated respectively with datum at 60 A and 100 A. The results show that the model reflects the basic characteristics of voltage non-uniformity and provides the beneficial reference for fuel cell control and single cell voltage detection.

  11. Model-Based Design of Energy Efficient Palladium Membrane Water Gas Shift Fuel Processors for PEM Fuel Cell Power Plants

    Science.gov (United States)

    Gummalla, Mallika; Vanderspurt, Thomas Henry; Emerson, Sean; She, Ying; Dardas, Zissis; Olsommer, Benoît

    An integrated, palladium alloy membrane Water-Gas Shift (WGS) reactor can significantly reduce the size, cost and complexity of a fuel processor for a Polymer Electrolyte Membrane fuel cell power system.

  12. Modeling the influence of precursor volatility and molecular structure on secondary organic aerosol formation using evaporated fuel experiments

    Directory of Open Access Journals (Sweden)

    S. H. Jathar

    2013-09-01

    Full Text Available We use SOA production data from an ensemble of evaporated fuels to test various SOA formation models. Except for gasoline, traditional SOA models focusing exclusively on volatile species in the fuels under-predict the observed SOA formation. These models can be improved dramatically by accounting for lower volatility species, but at the cost of a large set of free parameters. In contrast, a SOA model based only on the volatility of the precursor, starting with the volatility distribution of the evaporated fuels and optimized for the volatility reduction of first-generation products, reasonably reproduces the observed SOA formation with relatively few free parameters. The exceptions are exotic fuels such as Fischer-Tropsch fuels that expose the central assumption of the volatility based model that most emissions consist of complex mixtures displaying reasonably average behavior. However, for the vast majority of fuels, the volatility based model performs well.

  13. Modelling of Physical, Chemical, and Material Properties of Solid Oxide Fuel Cells

    Directory of Open Access Journals (Sweden)

    Jakub Kupecki

    2015-01-01

    Full Text Available This paper provides a review of modelling techniques applicable for system-level studies to account for physical, chemical, and material properties of solid oxide fuel cells. Functionality of 0D to 3D models is discussed and selected examples are given. Author provides information on typical length scales in evaluation of power systems with solid oxide fuel cells. In each section, proper examples of previous studies done in the field of 0D–3D modelling are recalled and discussed.

  14. Modelling and Evaluation of Heating Strategies for High Temperature Polymer Electrolyte Membrane Fuel Cell Stacks

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2008-01-01

    Experiments were conducted on two different cathode air cooled high temperature PEM (HTPEM) fuel cell stacks; a 30 cell 400W prototype stack using two bipolar plates per cell, and a 65 cell 1 kW commercial stack using one bipolar plate per cell. The work seeks to examine the use of different...... heating strategies and find a strategy suited for fast startup of the HTPEM fuel cell stacks. Fast start-up of these high temperature systems enables use in a wide range of applications, such as automotive and auxiliary power units, where immediate system response is needed. The development of a dynamic...... model to simulate the temperature development of a fuel cell stack during heating can be used for assistance in system and control design. The heating strategies analyzed and tested reduced the startup time of one of the fuel cell stacks from 1 h to about 6 min....

  15. Modeling and analysis of tritium dynamics in a DT fusion fuel cycle

    Science.gov (United States)

    Kuan, William

    1998-11-01

    A number of crucial design issues have a profound effect on the dynamics of the tritium fuel cycle in a DT fusion reactor, where the development of appropriate solutions to these issues is of particular importance to the introduction of fusion as a commercial system. Such tritium-related issues can be classified according to their operational, safety, and economic impact to the operation of the reactor during its lifetime. Given such key design issues inherent in next generation fusion devices using the DT fuel cycle development of appropriate models can then lead to optimized designs of the fusion fuel cycle for different types of DT fusion reactors. In this work, two different types of modeling approaches are developed and their application to solving key tritium issues presented. For the first approach, time-dependent inventories, concentrations, and flow rates characterizing the main subsystems of the fuel cycle are simulated with a new dynamic modular model of a fusion reactor's fuel cycle, named X-TRUFFLES (X-Windows TRitiUm Fusion Fuel cycLE dynamic Simulation). The complex dynamic behavior of the recycled fuel within each of the modeled subsystems is investigated using this new integrated model for different reactor scenarios and design approaches. Results for a proposed fuel cycle design taking into account current technologies are presented, including sensitivity studies. Ways to minimize the tritium inventory are also assessed by examining various design options that could be used to minimize local and global tritium inventories. The second modeling approach involves an analytical model to be used for the calculation of the required tritium breeding ratio, i.e., a primary design issue which relates directly to the feasibility and economics of DT fusion systems. A time-integrated global tritium balance scheme is developed and appropriate analytical expressions are derived for tritium self-sufficiency relevant parameters. The easy exploration of the large

  16. A Mathematical Model for Predicting the Life of PEM Fuel Cell Membranes Subjected to Hydration Cycling

    CERN Document Server

    Burlatsky, S F; O'Neill, J; Atrazhev, V V; Varyukhin, A N; Dmitriev, D V; Erikhman, N S

    2013-01-01

    Under typical PEM fuel cell operating conditions, part of membrane electrode assembly is subjected to humidity cycling due to variation of inlet gas RH and/or flow rate. Cyclic membrane hydration/dehydration would cause cyclic swelling/shrinking of the unconstrained membrane. In a constrained membrane, it causes cyclic stress resulting in mechanical failure in the area adjacent to the gas inlet. A mathematical modeling framework for prediction of the lifetime of a PEM FC membrane subjected to hydration cycling is developed in this paper. The model predicts membrane lifetime as a function of RH cycling amplitude and membrane mechanical properties. The modeling framework consists of three model components: a fuel cell RH distribution model, a hydration/dehydration induced stress model that predicts stress distribution in the membrane, and a damage accrual model that predicts membrane life-time. Short descriptions of the model components along with overall framework are presented in the paper. The model was used...

  17. Study of visualized simulation and analysis of nuclear fuel cycle system based on multilevel flow model

    Institute of Scientific and Technical Information of China (English)

    LIU Jing-Quan; YOSHIKAWA Hidekazu; ZHOU Yang-Ping

    2005-01-01

    Complex energy and environment system, especially nuclear fuel cycle system recently raised social concerns about the issues of economic competitiveness, environmental effect and nuclear proliferation. Only under the condition that those conflicting issues are gotten a consensus between stakeholders with different knowledge background, can nuclear power industry be continuingly developed. In this paper, a new analysis platform has been developed to help stakeholders to recognize and analyze various socio-technical issues in the nuclear fuel cycle system based on the functional modeling method named Multilevel Flow Models (MFM) according to the cognition theory of human being. Its character is that MFM models define a set of mass, energy and information flow structures on multiple levels of abstraction to describe the functional structure of a process system and its graphical symbol representation and the means-end and part-whole hierarchical flow structure to make the represented process easy to be understood. Based upon this methodology, a micro-process and a macro-process of nuclear fuel cycle system were selected to be simulated and some analysis processes such as economics analysis, environmental analysis and energy balance analysis related to those flows were also integrated to help stakeholders to understand the process of decision-making with the introduction of some new functions for the improved Multilevel Flow Models Studio, and finally the simple simulation such as spent fuel management process simulation and money flow of nuclear fuel cycle and its levelised cost analysis will be represented as feasible examples.

  18. The need for nano-scale modeling in solid oxide fuel cells.

    Science.gov (United States)

    Ryan, E M; Recknagle, K P; Liu, W; Khaleel, M A

    2012-08-01

    Solid oxide fuel cells (SOFCs) are high temperature fuel cells, which are being developed for large scale and distributed power systems. SOFCs promise to provide cleaner, more efficient electricity than traditional fossil fuel burning power plants. Research over the last decade has improved the design and materials used in SOFCs to increase their performance and stability for long-term operation; however, there are still challenges for SOFC researchers to overcome before SOFCs can be considered competitive with traditional fossil fuel burning and renewable power systems. In particular degradation due to contaminants in the fuel and oxidant stream is a major challenge facing SOFCs. In this paper we discuss ongoing computational and experimental research into different degradation and design issues in SOFC electrodes. We focus on contaminants in gasified coal which cause electrochemical and structural degradation in the anode, and chromium poisoning which affects the electrochemistry of the cathode. Due to the complex microstructures and multi-physics of SOFCs, multi-scale computational modeling and experimental research is needed to understand the detailed physics behind different degradation mechanisms, the local conditions within the cell which facilitate degradation, and its effects on the overall SOFC performance. We will discuss computational modeling research of SOFCs at the macro-, meso- and nano-scales which is being used to investigate the performance and degradation of SOFCs. We will also discuss the need for a multi-scale modeling framework of SOFCs, and the application of computational and multi-scale modeling to several degradation issues in SOFCs.

  19. Characterisation and modelling of a high temperature PEM fuel cell stack using electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jespersen, J.L. [Danish Technological Institute, Kongsvang Alle 29, DK-8000 Arhus C (Denmark); Schaltz, E.; Kaer, S.K. [Department of Energy Technology, Aalborg University, Pontoppidanstraede 101, DK-9220 Aalborg East (Denmark); Andreasen, S.J.

    2009-08-15

    In designing and controlling fuel cell systems, it is advantageous to have models which predict fuel cell behaviour in steady-state as well as in dynamic operation. This work examines the use of electro-chemical impedance spectroscopy (EIS) for characterising and developing an impedance model for a high temperature PEM (HT-PEM) fuel cell stack. A Labview virtual instrument has been developed to perform the signal generation and data acquisition which is needed to perform EIS. The typical output of an EIS measurement on a fuel cell is a Nyquist plot, which shows the imaginary and real parts of the impedance of the measured system. The full stack impedance depends on the impedance of each of the single cells of the stack. Equivalent circuit models for each single cell can be used to predict the stack impedance at different temperature profiles of the stack. The information available in such models can be used to predict the fuel cell stack performance, e.g. in systems where different electronic components introduce current harmonics. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  20. Use of multiscale zirconium alloy deformation models in nuclear fuel behavior analysis

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, Robert; Tomé, Carlos; Liu, Wenfeng; Alankar, Alankar; Subramanian, Gopinath; Stanek, Christopher

    2017-01-01

    Accurate prediction of cladding mechanical behavior is a key aspect of modeling nuclear fuel behavior, especially for conditions of pellet-cladding interaction (PCI), reactivity-initiated accidents (RIA), and loss of coolant accidents (LOCA). Current approaches to fuel performance modeling rely on empirical models for cladding creep, growth and plastic deformation, which are limited to the materials and conditions for which the models were developed. CASL has endeavored to improve upon this approach by incorporating a microstructurally-based, atomistically-informed, zirconium alloy mechanical deformation analysis capability into the BISON-CASL engineering scale fuel performance code. Specifically, the viscoplastic self-consistent (VPSC) polycrystal plasticity modeling approach, developed by Lebensohn and Tome´ [2], has been coupled with BISON-CASL to represent the mechanistic material processes controlling the deformation behavior of the cladding. A critical component of VPSC is the representation of the crystallographic orientation of the grains within the matrix material and the ability to account for the role of texture on deformation. The multiscale modeling of cladding deformation mechanisms allowed by VPSC far exceed the functionality of typical semi-empirical constitutive models employed in nuclear fuel behavior codes to model irradiation growth and creep, thermal creep, or plasticity. This paper describes the implementation of an interface between VPSC and BISON-CASL and provides initial results utilizing the coupled functionality.

  1. Dynamic Thermal Model And Control Of A Pem Fuel Cell System

    DEFF Research Database (Denmark)

    Liso, Vincenzo; Nielsen, Mads Pagh

    2013-01-01

    A lumped parameter dynamic model is developed for predicting the stack performance, temperatures of the exit reactant gases and coolant liquid outlet in a proton-exchange membrane fuel cell (PEMFC) system. The air compressor, humidifier and cooling heat exchanger models are integrated to study th...

  2. A 3D model for PEM fuel cells operated on reformate

    Science.gov (United States)

    Zhou, Tianhong; Liu, Hongtan

    A three-dimensional mathematical model for PEM fuel cells operated on reformate is developed based on our previous established fuel cell model [Int. J. Transport Phenomena 3 (2001) 177], by incorporating the adsorption and oxidation kinetics of CO on platinum surface proposed by Springer et al. [Proceedings of the Electrochemical Society, Montreal, Canada, 1997; J. Electrochem. Soc. 148 (2001) A11]. This model is capable of studying the effect of CO poisoning as well as the hydrogen dilution effect by inert gases. The adsorption and oxidation kinetics of CO on a platinum surface are incorporated in the source terms of the species equations; thus, the basic form of the mathematical equations are the same as those used for PEM fuel cells operated on pure hydrogen. With this model, we can obtain detailed information on the CO poisoning and variation of CO and hydrogen concentrations inside the anode. The results from this 3D model reveal many new phenomena that cannot be obtained from previous 1D or 2D models. Results of the effects of various operating and design parameters, such as anode flow rate, gas diffuser porosity, gas diffuser thickness, and the width of the collector plate shoulder, are also presented. The modeling results demonstrate the value of this model as a design and optimization tool for the anode of PEM fuel cells operating on reformate.

  3. Knock prediction for dual fuel engines by using a simplified combustion model

    Institute of Scientific and Technical Information of China (English)

    费少梅; 刘震涛; 严兆大

    2003-01-01

    The present work used a methane-air mixture chemical kinetics scheme consisting of 119 elementary reaction steps and 41 chemical species to develop a simplified combustion model for prediction of the knock in dual fuel engines. Calculated values by the model for natural gas operation showed good agreement with corresponding experimental values over a broad range of operating conditions.

  4. Aerothermal modeling program, Phase 2, Element C: Fuel injector-air swirl characterization

    Science.gov (United States)

    Mostafa, A. A.; Mongia, H. C.; Mcdonnel, V. G.; Samuelsen, G. S.

    1987-01-01

    The main objectives of the NASA sponsored Aerothermal Modeling Program, Phase 2, Element C, are to collect benchmark quality data to quantify the fuel spray interaction with the turbulent swirling flows and to validate current and advanced two phase flow models. The technical tasks involved in this effort are discussed.

  5. Two-dimensional, isothermal, multi-component model for a polymer electrolyte membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Mahinpey, N.; Jagannathan, A.; Idem, R. [Regina Univ., SK (Canada). Faculty of Engineering

    2007-07-01

    A fuel cell is an electrochemical energy conversion device which is more efficient than an internal combustion engine in converting fuel to power. Numerous fuel cell models have been developed by a number of authors accounting for the various physical processes. Earlier models were restricted to being one dimensional, steady-state, and isothermal while more recent two-dimensional models had several limitations. This paper presented the results of a study that developed a two-dimensional computational fluid dynamics model of a polymer electrolyte membrane fuel cell using a finite element method to solve a multi-component transport model coupled with flow in porous media, charge balance, electrochemical kinetics, and rigorous water balance in the membrane. The mass transport, momentum transport, and electrochemical processes occurring in the membrane electrolyte and catalyst layers were modeled. The local equilibrium was assumed at the interfaces and the model was combined with the kinetics and was analytically solved for the anodic and cathodic current using an agglomerate spherical catalyst pellet. The paper compared the modeling results with previously published experimental data. The study investigated the effects of channel and bipolar plate shoulder size, porosity of the electrodes, temperature, relative humidity and current densities on the cell performance. It was concluded that smaller sized channels and bipolar plate shoulders were required to obtain higher current densities, although larger channels were satisfactory at moderate current densities. 13 refs., 5 figs.

  6. Physical characteristics of shrub and conifer fuels for fire behavior models

    Science.gov (United States)

    Jonathan R. Gallacher; Thomas H. Fletcher; Victoria Lansinger; Sydney Hansen; Taylor Ellsworth; David R. Weise

    2017-01-01

    The physical properties and dimensions of foliage are necessary inputs for some fire spread models. Currently, almost no data exist on these plant characteristics to fill this need. In this report, we measured the physical properties and dimensions of the foliage from 10 live shrub and conifer fuels throughout a 1-year period. We developed models to predict relative...

  7. BEHAVE: fire behavior prediction and fuel modeling system-BURN Subsystem, part 1

    Science.gov (United States)

    Patricia L. Andrews

    1986-01-01

    Describes BURN Subsystem, Part 1, the operational fire behavior prediction subsystem of the BEHAVE fire behavior prediction and fuel modeling system. The manual covers operation of the computer program, assumptions of the mathematical models used in the calculations, and application of the predictions.

  8. Modelling microbial fuel cells with suspended cells and added electron transfer mediator

    NARCIS (Netherlands)

    Picoreanu, C.; Katuri, K.P.; Van Loosdrecht, M.C.M.; Head, I.M.; Scott, K.

    2009-01-01

    Derivation of a mathematical model for microbial fuel cells (MFC) with suspended biomass and added electron-transfer mediator is described. The model is based on mass balances for several dissolved chemical species such as substrate, oxidized mediator and reduced mediator. Biological, chemical and e

  9. A comparison of geospatially modeled fire behavior and potential application to fire and fuels management for the Savannah River Site.

    Energy Technology Data Exchange (ETDEWEB)

    Kurth, Laurie; Hollingsworth, LaWen; Shea, Dan

    2011-12-20

    This study evaluates modeled fire behavior for the Savannah River Site in the Atlantic Coastal Plain of the southeastern U.S. using three data sources: FCCS, LANDFIRE, and SWRA. The Fuel Characteristic Classification System (FCCS) was used to build fuelbeds from intensive field sampling of 629 plots. Custom fire behavior fuel models were derived from these fuelbeds. LANDFIRE developed surface fire behavior fuel models and canopy attributes for the U.S. using satellite imagery informed by field data. The Southern Wildfire Risk Assessment (SWRA) developed surface fire behavior fuel models and canopy cover for the southeastern U.S. using satellite imagery.

  10. FITTING A THREE DIMENSIONAL PEM FUEL CELL MODEL TO MEASUREMENTS BY TUNING THE POROSITY AND

    DEFF Research Database (Denmark)

    Bang, Mads; Odgaard, Madeleine; Condra, Thomas Joseph

    2004-01-01

    PEM fuel cell are dealt with in detail.The model solves the convective and diffusive transport of thegaseous phase in the fuel cell and allows prediction of theconcentration of the species present. A special feature of themodel is a method that allows detailed modelling and predictionof electrode kinetics...... dependency on the gas concentration andactivation overpotential can thereby be addressed. The proposedmodel makes it possible to predict the effect of geometrical andmaterial properties on the fuel cell?s performance. It is shownhow the ionic conductivity and porosity of the catalyst layeraffects...... the distribution of current density and further how thisaffects the polarization curve.The porosity and conductivity of the catalyst layer are some ofthe most difficult parameters to measure, estimate and especiallycontrol. Yet the proposed model shows how these two parameterscan have significant influence...

  11. Deep removal of 4,6-dimethyldibenzothiophene from model transportation diesel fuels over reactive adsorbent

    Directory of Open Access Journals (Sweden)

    Shengqiang Wang

    2012-06-01

    Full Text Available This paper presents a new reactive adsorbent used to effectively remove 4,6-dimethyldibenzothiophene (4,6-DMDBT from model transportation diesel fuels. This reactive adsorbent was composed of formaldehyde, phosphotungstic acid and mesoporous silica gel. The experiment was based on an assumed condensation reaction of 4,6-DMDBT with formaldehyde using phosphotungstic acid as catalyst in pore spaces. The effect of temperature and the amount of formaldehyde and phosphotungstic acid loaded on the substrate were investigated in a batch system. In the breakthrough experiment, three different model diesel fuels containing 1000 mg/kg 4,6-DMDBT were pumped through a fixed-bed reactor packed with reactive adsorbent at constant temperature and atmospheric pressure, respectively. The experimental results showed that sulfur-free model fuel was obtained at 80ºC despite the presence of aromatics. The sulfur capacity of regenerated reactive adsorbent was almost totally recovered.

  12. Prediction models for performance and emissions of a dual fuel CI engine using ANFIS

    Indian Academy of Sciences (India)

    A Adarsh Rai; P Srinivasa Pai; B R Shrinivasa Rao

    2015-04-01

    Dual fuel engines are being used these days to overcome shortage of fossil fuels and fulfill stringent exhaust gas emission regulations. They have several advantages over conventional diesel engines. In this context, this paper makes use of experimental results obtained from a dual fuel engine for developing models to predict performance and emission parameters. Conventional modelling efforts to understand the relationships between the input and the output variables, requires thermodynamic analysis which is complex and time consuming. As a result, efforts have been made to use artificial intelligence modelling techniques like fuzzy logic, Artificial Neural Network (ANN), Genetic Algorithm (GA), etc. This paper uses a neuro fuzzy modelling technique, Adaptive Neuro Fuzzy Inference System (ANFIS) for developing prediction models for performance and emission parameter of a dual fuel engine. Percentage load, percentage Liquefied Petroleum Gas (LPG) and Injection Timing (IT) have been used as input parameters, whereas output parameters include Brake Specific Energy Consumption (BSEC), Brake Thermal Efficiency (BTE), Exhaust Gas Temperature (EGT) and smoke. In order to further improve the prediction accuracy of the model, GA has been used to optimize ANFIS. GA optimized ANFIS gives higher prediction accuracy of more than 90% for all parameters except for smoke, where there is a substantial improvement from 46.67% to 73.33%, when compared to conventional ANFIS model.

  13. A Model for Nitrogen Chemistry in Oxy-Fuel Combustion of Pulverized Coal

    OpenAIRE

    Hashemi, Hamid; Hansen, Stine; Toftegaard, Maja Bøg; Pedersen, Kim Hougaard; Jensen, Anker Degn; Dam-Johansen, Kim; Glarborg, Peter

    2011-01-01

    In this work, a model for the nitrogen chemistry in the oxy-fuel combustion of pulverized coal has been developed. The model is a chemical reaction engineering type of model with a detailed reaction mechanism for the gas-phase chemistry, together with a simplified description of the mixing of flows, heating and devolatilization of particles, and gas–solid reactions. The model is validated by comparison with entrained flow reactor results from the present work and from the literature on pulver...

  14. Proton Exchange Membrane Fuel Cell Modeling Based on Seeker Optimization Algorithm

    Institute of Scientific and Technical Information of China (English)

    LI Qi; DAI Chao-hua; Chen Wei-rong; JIA Jun-bo; HAN Ming

    2008-01-01

    Seeker optimization algorithm (SOA) has applications in continuous space of swarm intelligence. In the fields of proton ex-change membrane fuel cell (PEMFC) modeling, SOA was proposed to research a set of optimized parameters in PEMFC polariza-tion curve model. Experimental result showed that the mean square error of the optimization modeling strategy was only 6.9 × 10-23. Hence, the optimization model could fit the experiment data with high precision.

  15. Numerical modeling on homogeneous charge compression ignition combustion engine fueled by diesel-ethanol blends

    Directory of Open Access Journals (Sweden)

    Hanafi H.

    2016-01-01

    Full Text Available This paper investigates the performance and emission characteristics of HCCI engines fueled with oxygenated fuels (ethanol blend. A modeling study was conducted to investigate the impact of ethanol addition on the performance, combustion and emission characteristics of a Homogeneous Charge Compression Ignition (HCCI engine fueled by diesel. One dimensional simulation was conducted using the renowned commercial software for diesel and its blend fuels with 5% (E5 and 10% ethanol (E10 (in vol. under full load condition at variable engine speed ranging from 1000 to 2750 rpm with 250 rpm increment. The model was then validated with other researcher’s experimental result. Model consists of intake and exhaust systems, cylinder, head, valves and port geometries. Performance tests were conducted for volumetric efficiency, brake engine torque, brake power, brake mean effective pressure, brake specific fuel consumption, and brake thermal efficiency, while exhaust emissions were analyzed for carbon monoxide (CO and unburned hydrocarbons (HC. The results showed that blending diesel with ethanol increases the volumetric efficiency, brake specific fuel consumption and brake thermal efficiency, while it decreases brake engine torque, brake power and brake mean effective pressure. In term of emission characteristics, the CO emissions concentrations in the engine exhaust decrease significantly with ethanol as additive. But for HC emission, its concentration increase when apply in high engine speed. In conclusion, using Ethanol as fuel additive blend with Diesel operating in HCCI shows a good result in term of performance and emission in low speed but not recommended to use in high speed engine. Ethanol-diesel blends need to researched more to make it commercially useable.

  16. Modeling and energy management control design for a fuel cell hybrid passenger bus

    Science.gov (United States)

    Simmons, Kyle; Guezennec, Yann; Onori, Simona

    2014-01-01

    This paper presents the modeling and supervisory energy management design of a hybrid fuel cell/battery-powered passenger bus. With growing concerns about petroleum usage and greenhouse gas emissions in the transportation sector, finding alternative methods for vehicle propulsion is necessary. Proton Exchange Membrane (PEM) fuel cell systems are viable possibilities for energy converters due to their high efficiencies and zero emissions. It has been shown that the benefits of PEM fuel cell systems can be greatly improved through hybridization. In this work, the challenge of developing an on-board energy management strategy with near-optimal performance is addressed by a two-step process. First, an optimal control based on Pontryagin's Minimum Principle (PMP) is implemented to find the global optimal solution which minimizes fuel consumption, for different drive cycles, with and without grade. The optimal solutions are analyzed in order to aid in development of a practical controller suitable for on-board implementation, in the form of an Auto-Regressive Moving Average (ARMA) regulator. Simulation results show that the ARMA controller is capable of achieving fuel economy within 3% of the PMP controller while being able to limit the transient demand on the fuel cell system.

  17. One dimensional modeling of a diesel-CNG dual fuel engine

    Science.gov (United States)

    Azman, Putera Adam; Fawzi, Mas; Ismail, Muammar Mukhsin; Osman, Shahrul Azmir

    2017-04-01

    Some of the previous studies have shown that the use of compressed natural gas (CNG) in diesel engines potentially produce engine performance improvement and exhaust gas emission reduction, especially nitrogen oxides, unburned hydrocarbons, and carbon dioxide. On the other hand, there are other researchers who claimed that the use of CNG increases exhaust gas emissions, particularly nitrogen oxides. In this study, a one-dimensional model of a diesel-CNG dual fuel engine was made based on a 4-cylinder 2.5L common rail direct injection diesel engine. The software used is GT-Power, and it was used to analyze the engine performance and exhaust gas emissions of several diesel-CNG dual fuel blend ratios, i.e. 100:0, 90:10, 80:20, 70:30, 60:40 and 50:50. The effect of 100%, 75%, 50% engine loads on the exhaust gas emissions were also studied. The result shows that all diesel-CNG fuel blends produces higher brake torque and brake power at engine speed of 2000-3000 rpm compared with 100% diesel. The 50:50 diesel-CNG blend produces the highest brake torque and brake power, but also has the highest brake specific fuel consumption. As a higher percentage of CNG added to the dual fuel blend, unburned hydrocarbons and carbon monoxide emission increased while carbon dioxide emission decreased. The nitrogen oxides emission concentration is generally unaffected by any change of the dual fuel ratio.

  18. Multiphysics Modeling of a Single Channel in a Nuclear Thermal Propulsion Grooved Ring Fuel Element

    Science.gov (United States)

    Kim, Tony; Emrich, William J., Jr.; Barkett, Laura A.; Mathias, Adam D.; Cassibry, Jason T.

    2013-01-01

    In the past, fuel rods have been used in nuclear propulsion applications. A new fuel element concept that reduces weight and increases efficiency uses a stack of grooved discs. Each fuel element is a flat disc with a hole on the interior and grooves across the top. Many grooved ring fuel elements for use in nuclear thermal propulsion systems have been modeled, and a single flow channel for each design has been analyzed. For increased efficiency, a fuel element with a higher surface-area-to-volume ratio is ideal. When grooves are shallower, i.e., they have a lower surface area, the results show that the exit temperature is higher. By coupling the physics of turbulence with those of heat transfer, the effects on the cooler gas flowing through the grooves of the thermally excited solid can be predicted. Parametric studies were done to show how a pressure drop across the axial length of the channels will affect the exit temperatures of the gas. Geometric optimization was done to show the behaviors that result from the manipulation of various parameters. Temperature profiles of the solid and gas showed that more structural optimization is needed to produce the desired results. Keywords: Nuclear Thermal Propulsion, Fuel Element, Heat Transfer, Computational Fluid Dynamics, Coupled Physics Computations, Finite Element Analysis

  19. Biojet Fuels and Emissions Mitigation in Aviation: an Integrated Assessment Modeling Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wise, Marshall A.; Muratori, Matteo; Kyle, Gordon P.

    2017-05-01

    Although the aviation sector is a relatively small contributor to total greenhouse gas emissions, it is a fast-growing, fossil fuel-intensive transportation mode. Because aviation is a mode for which liquid fuels currently have no practical substitute, biofuels are gaining attention as a promising cleaner alternative. In this paper, we use the GCAM integrated assessment model to develop scenarios that explore the potential impact of biojet fuels for use in aviation in the context of broader climate change mitigation. We show that a carbon price would have a significant impact on the aviation sector. In the absence of alternatives to jet fuel from petroleum, mitigation potential is limited and would be at the expense of aviation service demand growth. However, mitigation efforts through the increased use of biojet fuels show potential to reduce the carbon intensity of aviation, and may not have a significant impact on carbon mitigation and bioenergy use in the rest of the energy system. The potential of biofuel to decarbonize air transport is significantly enhanced when carbon dioxide capture and storage (CCS) is used in the conversion process to produce jet fuels from biomass feedstock.

  20. Summary report on the fuel performance modeling of the AFC-2A, 2B irradiation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Pavel G. Medvedev

    2013-09-01

    The primary objective of this work at the Idaho National Laboratory (INL) is to determine the fuel and cladding temperature history during irradiation of the AFC-2A, 2B transmutation metallic fuel alloy irradiation experiments containing transuranic and rare earth elements. Addition of the rare earth elements intends to simulate potential fission product carry-over from pyro-metallurgical reprocessing. Post irradiation examination of the AFC-2A, 2B rodlets revealed breaches in the rodlets and fuel melting which was attributed to the release of the fission gas into the helium gap between the rodlet cladding and the capsule which houses six individually encapsulated rodlets. This release is not anticipated during nominal operation of the AFC irradiation vehicle that features a double encapsulated design in which sodium bonded metallic fuel is separated from the ATR coolant by the cladding and the capsule walls. The modeling effort is focused on assessing effects of this unanticipated event on the fuel and cladding temperature with an objective to compare calculated results with the temperature limits of the fuel and the cladding.

  1. Radiation induced dissolution of UO 2 based nuclear fuel - A critical review of predictive modelling approaches

    Science.gov (United States)

    Eriksen, Trygve E.; Shoesmith, David W.; Jonsson, Mats

    2012-01-01

    Radiation induced dissolution of uranium dioxide (UO 2) nuclear fuel and the consequent release of radionuclides to intruding groundwater are key-processes in the safety analysis of future deep geological repositories for spent nuclear fuel. For several decades, these processes have been studied experimentally using both spent fuel and various types of simulated spent fuels. The latter have been employed since it is difficult to draw mechanistic conclusions from real spent nuclear fuel experiments. Several predictive modelling approaches have been developed over the last two decades. These models are largely based on experimental observations. In this work we have performed a critical review of the modelling approaches developed based on the large body of chemical and electrochemical experimental data. The main conclusions are: (1) the use of measured interfacial rate constants give results in generally good agreement with experimental results compared to simulations where homogeneous rate constants are used; (2) the use of spatial dose rate distributions is particularly important when simulating the behaviour over short time periods; and (3) the steady-state approach (the rate of oxidant consumption is equal to the rate of oxidant production) provides a simple but fairly accurate alternative, but errors in the reaction mechanism and in the kinetic parameters used may not be revealed by simple benchmarking. It is essential to use experimentally determined rate constants and verified reaction mechanisms, irrespective of whether the approach is chemical or electrochemical.

  2. Characterizing model uncertainties in the life cycle of lignocellulose-based ethanol fuels.

    Science.gov (United States)

    Spatari, Sabrina; MacLean, Heather L

    2010-11-15

    Renewable and low carbon fuel standards being developed at federal and state levels require an estimation of the life cycle carbon intensity (LCCI) of candidate fuels that can substitute for gasoline, such as second generation bioethanol. Estimating the LCCI of such fuels with a high degree of confidence requires the use of probabilistic methods to account for known sources of uncertainty. We construct life cycle models for the bioconversion of agricultural residue (corn stover) and energy crops (switchgrass) and explicitly examine uncertainty using Monte Carlo simulation. Using statistical methods to identify significant model variables from public data sets and Aspen Plus chemical process models,we estimate stochastic life cycle greenhouse gas (GHG) emissions for the two feedstocks combined with two promising fuel conversion technologies. The approach can be generalized to other biofuel systems. Our results show potentially high and uncertain GHG emissions for switchgrass-ethanol due to uncertain CO₂ flux from land use change and N₂O flux from N fertilizer. However, corn stover-ethanol,with its low-in-magnitude, tight-in-spread LCCI distribution, shows considerable promise for reducing life cycle GHG emissions relative to gasoline and corn-ethanol. Coproducts are important for reducing the LCCI of all ethanol fuels we examine.

  3. Statistical model for combustion of high-metal magnesium-based hydro-reactive fuel

    Institute of Scientific and Technical Information of China (English)

    Hu Jian-Xin; Han Chao; Xia Zhi-Xun; Huang Li-Ya; Huang Xu

    2012-01-01

    We investigate experimentally and analytically the combustion behavior of a high-metal magnesium-based hydro-reactive fuel under high temperature gaseous atmosphere.The fuel studied in this paper contains 73% magnesium powders.An experimental system is designed and experimeuts are carried out in both argon and water vapor atmospheres.It is found that the burning surface temperature of the fuel is higher in water vapor than that in argon and both of them are higher than the melting point of magnesium,which indicates the molten state of magnesium particles in the burning surface of the fuel.Based on physical considerations and experimental results,a mathematical one-dimensional model is formulated to describe the combustion behavior of the high-metal magnesium-based hydro-reactive fuel.The model enables the evaluation of the burning surface temperature,the burning rate and the flame standoff distance each as a function of chamber pressure and water vapor concentration.The results predicted by the model show that the burning rate and the surface temperature increase when the chamber pressure and the water vapor concentration increase,which are in agreement with the observed experimental trends.

  4. Preliminary Mathematical Model for Jet Fuel Exacerbated Noise-Induced Hearing Loss

    Science.gov (United States)

    2013-01-01

    hearing loss . Noise alone induces hearing loss due to loss of hair cells in the cochlea, associated with oxidative stress. Jet fuel toxicity in association with noise may be at least partially explained by increased free radical production and oxidative stress at the cellular level, resulting in hair cell dysfunction and loss. This project combines a physiologically-based pharmacokinetic (PBPK) model to describe jet fuel component concentrations in the cochlea with pharmacodynamic (PD) models of free radical formation in the cochlea by both noise and

  5. Input/output models for general aviation piston-prop aircraft fuel economy

    Science.gov (United States)

    Sweet, L. M.

    1982-01-01

    A fuel efficient cruise performance model for general aviation piston engine airplane was tested. The following equations were made: (1) for the standard atmosphere; (2) airframe-propeller-atmosphere cruise performance; and (3) naturally aspirated engine cruise performance. Adjustments are made to the compact cruise performance model as follows: corrected quantities, corrected performance plots, algebraic equations, maximize R with or without constraints, and appears suitable for airborne microprocessor implementation. The following hardwares are recommended: ignition timing regulator, fuel-air mass ration controller, microprocessor, sensors and displays.

  6. New Procedure to Develop Lumped Kinetic Models for Heavy Fuel Oil Combustion

    KAUST Repository

    Han, Yunqing

    2016-09-20

    A new procedure to develop accurate lumped kinetic models for complex fuels is proposed, and applied to the experimental data of the heavy fuel oil measured by thermogravimetry. The new procedure is based on the pseudocomponents representing different reaction stages, which are determined by a systematic optimization process to ensure that the separation of different reaction stages with highest accuracy. The procedure is implemented and the model prediction was compared against that from a conventional method, yielding a significantly improved agreement with the experimental data. © 2016 American Chemical Society.

  7. The modeling of a standalone solid-oxide fuel cell auxiliary power unit

    Science.gov (United States)

    Lu, N.; Li, Q.; Sun, X.; Khaleel, M. A.

    In this research, a Simulink model of a standalone vehicular solid-oxide fuel cell (SOFC) auxiliary power unit (APU) is developed. The SOFC APU model consists of three major components: a controller model; a power electronics system model; and an SOFC plant model, including an SOFC stack module, two heat exchanger modules, and a combustor module. This paper discusses the development of the nonlinear dynamic models for the SOFC stacks, the heat exchangers and the combustors. When coupling with a controller model and a power electronic circuit model, the developed SOFC plant model is able to model the thermal dynamics and the electrochemical dynamics inside the SOFC APU components, as well as the transient responses to the electric loading changes. It has been shown that having such a model for the SOFC APU will help design engineers to adjust design parameters to optimize the performance. The modeling results of the SOFC APU heat-up stage and the output voltage response to a sudden load change are presented in this paper. The fuel flow regulation based on fuel utilization is also briefly discussed.

  8. Modeling optimizes PEM fuel cell durability using three-dimensional multi-phase computational fluid dynamics model

    Directory of Open Access Journals (Sweden)

    Maher A.R. Sadiq Al-Baghdadi

    2010-05-01

    Full Text Available Damage mechanisms in a proton exchange membrane (PEM fuel cell are accelerated by mechanical stresses arising during fuel cell assembly (bolt assembling, and the stresses arise during fuel cell running, because it consists of the materials with different thermal expansion and swelling coefficients. Therefore, in order to acquire a complete understanding of the damage mechanisms in the membrane and gas diffusion layers, mechanical response under steady-state hygro-thermal stresses should be studied under real cell operating conditions and in real cell geometry (three-dimensional. In this work, full three-dimensional, non-isothermal computational fluid dynamics model of a PEM fuel cell has been developed to simulate the hygro and thermal stresses in PEM fuel cell, which are occurring during the cell operation due to the changes of temperature and relative humidity. A unique feature of the present model is to incorporate the effect of hygro and thermal stresses into actual three-dimensional fuel cell model. The mechanical behaviour of the membrane, catalyst layers, and gas diffusion layers during the operation of a unit cell has been studied and investigated. The model is shown to be able to understand the many interacting, complex electrochemical, transport phenomena, and stresses distribution that have limited experimental data. The results show that the non-uniform distribution of stresses, caused by the temperature gradient in the cell, induces localized bending stresses, which can contribute to delaminating between the membrane and the gas diffusion layers. These results may explain the occurrence of cracks and pinholes in the membrane during regular cell operation. This model is used to study the effect of operating, design, and material parameters on fuel cell hygro-thermal stresses in polymer membrane, catalyst layers, and gas diffusion layers. Detailed analyses of the fuel cell durability under various operating conditions have been

  9. Modeling of molecular and particulate transport in dry spent nuclear fuel canisters

    Science.gov (United States)

    Casella, Andrew M.

    2007-09-01

    The transportation and storage of spent nuclear fuel is one of the prominent issues facing the commercial nuclear industry today, as there is still no general consensus regarding the near- and long-term strategy for managing the back-end of the nuclear fuel cycle. The debate continues over whether the fuel cycle should remain open, in which case spent fuel will be stored at on-site reactor facilities, interim facilities, or a geologic repository; or if the fuel cycle should be closed, in which case spent fuel will be recycled. Currently, commercial spent nuclear fuel is stored at on-site reactor facilities either in pools or in dry storage containers. Increasingly, spent fuel is being moved to dry storage containers due to decreased costs relative to pools. As the number of dry spent fuel containers increases and the roles they play in the nuclear fuel cycle increase, more regulations will be enacted to ensure that they function properly. Accordingly, they will have to be carefully analyzed for normal conditions, as well as any off-normal conditions of concern. This thesis addresses the phenomena associated with one such concern; the formation of a microscopic through-wall breach in a dry storage container. Particular emphasis is placed on the depressurization of the canister, release of radioactivity, and plugging of the breach due to deposition of suspended particulates. The depressurization of a dry storage container upon the formation of a breach depends on the temperature and quantity of the fill gas, the pressure differential across the breach, and the size of the breach. The first model constructed in this thesis is capable of determining the depressurization time for a breached container as long as the associated parameters just identified allow for laminar flow through the breach. The parameters can be manipulated to quantitatively determine their effect on depressurization. This model is expanded to account for the presence of suspended particles. If

  10. Process Model of A Fusion Fuel Recovery System for a Direct Drive IFE Power Reactor

    Science.gov (United States)

    Natta, Saswathi; Aristova, Maria; Gentile, Charles

    2008-11-01

    A task has been initiated to develop a detailed representative model for the fuel recovery system (FRS) in the prospective direct drive inertial fusion energy (IFE) reactor. As part of the conceptual design phase of the project, a chemical process model is developed in order to observe the interaction of system components. This process model is developed using FEMLAB Multiphysics software with the corresponding chemical engineering module (CEM). Initially, the reactants, system structure, and processes are defined using known chemical species of the target chamber exhaust. Each step within the Fuel recovery system is modeled compartmentally and then merged to form the closed loop fuel recovery system. The output, which includes physical properties and chemical content of the products, is analyzed after each step of the system to determine the most efficient and productive system parameters. This will serve to attenuate possible bottlenecks in the system. This modeling evaluation is instrumental in optimizing and closing the fusion fuel cycle in a direct drive IFE power reactor. The results of the modeling are presented in this paper.

  11. Ionic conductivity studies of solid oxide fuel cell electrolytes and theoretical modeling of an entire solid oxide fuel cell

    Science.gov (United States)

    Pornprasertsuk, Rojana

    Because of the steep increase in oil prices, the global warming effect and the drive for energy independence, alternative energy research has been encouraged worldwide. The sustainable fuels such as hydrogen, biofuel, natural gas, and solar energy have attracted the attention of researchers. To convert these fuels into a useful energy source, an energy conversion device is required. Fuel cells are one of the energy conversion devices which convert chemical potentials into electricity. Due to their high efficiency, the ease to scale from 1 W range to megawatts range, no recharging requirement and the lack of CO2 and NOx emission (if H2 and air/O 2 are used), fuel cells have become a potential candidate for both stationary power generators and portable applications. This thesis has been focused primarily on solid oxide fuel cell (SOFC) studies due to its high efficiency, varieties of fuel choices, and no water management problem. At the present, however, practical applications of SOFCs are limited by high operating temperatures that are needed to create the necessary oxide-ion vacancy mobility in the electrolyte and to create sufficient electrode reactivities. This thesis introduces several experimental and theoretical approaches to lower losses both in the electrolyte and the electrodes. Yttria stabilized zirconia (YSZ) is commonly used as a solid electrolyte for SOFCs due to its high oxygen-ion conductivity. To improve the ionic conductivity for low temperature applications, an approach that involves dilating the structure by irradiation and introducing edge dislocations into the electrolyte was studied. Secondly, to understand the activation loss in SOFC, the kinetic Monte Carlo (KMC) technique was implemented to model the SOFC operation to determining the rate-limiting step due to the electrodes on different sizes of Pt catalysts. The isotope exchange depth profiling technique was employed to investigate the irradiation effect on the ionic transport in different

  12. Issues associated with modelling of proton exchange membrane fuel cell by computational fluid dynamics

    Science.gov (United States)

    Bednarek, Tomasz; Tsotridis, Georgios

    2017-03-01

    The objective of the current study is to highlight possible limitations and difficulties associated with Computational Fluid Dynamics in PEM single fuel cell modelling. It is shown that an appropriate convergence methodology should be applied for steady-state solutions, due to inherent numerical instabilities. A single channel fuel cell model has been taken as numerical example. Results are evaluated for quantitative as well qualitative points of view. The contribution to the polarization curve of the different fuel cell components such as bi-polar plates, gas diffusion layers, catalyst layers and membrane was investigated via their effects on the overpotentials. Furthermore, the potential losses corresponding to reaction kinetics, due to ohmic and mas transport limitations and the effect of the exchange current density and open circuit voltage, were also investigated. It is highlighted that the lack of reliable and robust input data is one of the issues for obtaining accurate results.

  13. Modelling of solid polymer and direct methanol fuel cells: Phenomenological equations and analytical solutions

    Science.gov (United States)

    Kauranen, P. S.

    1993-04-01

    In the solid state concept of a direct methanol fuel cell (DMFC), methanol is directly oxidized at the anode of a solid polymer electrolyte fuel cell (SPEFC). Mathematical modelling of the transport and reaction phenomena within the electrodes and the electrolyte membrane is needed in order to get a closer insight into the operation of the fuel cell. In the work, macro-homogenous porous electrode and dilute solution theories are used to derive the phenomenological equations describing the transport and reaction mechanisms in a SPEFC single cell. The equations are first derived for a conventional H2/air SPEFC, and then extended for a DMFC. The basic model is derived in a one dimensional form in which it is assumed that species transport take place only in the direction crossing the cell sandwich. In addition, two dimensional descriptions of the catalyst layer are reviewed.

  14. A model to predict failure of irradiated U–Mo dispersion fuel

    Energy Technology Data Exchange (ETDEWEB)

    Burkes, Douglas E.; Senor, David J.; Casella, Andrew M.

    2016-12-01

    Numerous global programs are focused on the continued development of existing and new research and test reactor fuels to achieve maximum attainable uranium loadings to support the conversion of a number of the world’s remaining high-enriched uranium fueled reactors to low-enriched uranium fuel. Some of these programs are focused on development and qualification of a fuel design that consists of a uranium-molybdenum (U-Mo) alloy dispersed in an aluminum matrix as one option for reactor conversion. The current paper extends a failure model originally developed for UO2-stainless steel dispersion fuels and used currently available thermal-mechanical property information for the materials of interest in the current proposed design. A number of fabrication and irradiation parameters were investigated to understand the conditions at which failure of the matrix, classified as pore formation in the matrix, might occur. The results compared well with experimental observations published as part of the Reduced Enrichment for Research and Test Reactors (RERTR)-6 and -7 mini-plate experiments. Fission rate, a function of the 235U enrichment, appeared to be the most influential parameter in premature failure, mainly as a result of increased interaction layer formation and operational temperature, which coincidentally decreased the yield strength of the matrix and caused more rapid fission gas production and recoil into the surrounding matrix material. Addition of silicon to the matrix appeared effective at reducing the rate of interaction layer formation and can extend the performance of a fuel plate under a certain set of irradiation conditions, primarily moderate heat flux and burnup. Increasing the dispersed fuel particle diameter may also be effective, but only when combined with other parameters, e.g., lower enrichment and increased Si concentration. The model may serve as a valuable tool in initial experimental design.

  15. Modeling of gas turbine - solid oxide fuel cell systems for combined propulsion and power on aircraft

    Science.gov (United States)

    Waters, Daniel Francis

    This dissertation investigates the use of gas turbine (GT) engine integrated solid oxide fuel cells (SOFCs) to reduce fuel burn in aircraft with large electrical loads like sensor-laden unmanned air vehicles (UAVs). The concept offers a number of advantages: the GT absorbs many SOFC balance of plant functions (supplying fuel, air, and heat to the fuel cell) thereby reducing the number of components in the system; the GT supplies fuel and pressurized air that significantly increases SOFC performance; heat and unreacted fuel from the SOFC are recaptured by the GT cycle offsetting system-level losses; good transient response of the GT cycle compensates for poor transient response of the SOFC. The net result is a system that can supply more electrical power more efficiently than comparable engine-generator systems with only modest (capture `down-the-channel' effects (a level of fidelity necessary for making meaningful performance, mass, and volume estimates). Models are created in a NASA-developed environment called Numerical Propulsion System Simulation (NPSS). A sensitivity analysis identifies important design parameters and translates uncertainties in model parameters into uncertainties in overall performance. GT-SOFC integrations reduce fuel burn 3-4% in 50 kW systems on 35 kN rated engines (all types) with overall uncertainty 3 in some cases) than generator-based systems before encountering turbine inlet temperature limits. Aerodynamic drag effects of engine-airframe integration are by far the most important limiter of the combined propulsion/electrical generation concept. However, up to 100-200 kW can be produced in a bypass ratio = 8, overall pressure ratio = 40 turbofan with little or no drag penalty. This study shows that it is possible to create cooperatively integrated GT-SOFC systems for combined propulsion and power with better overall performance than stand-alone components.

  16. Overview of lower length scale model development for accident tolerant fuels regarding U3Si2 fuel and FeCrAl cladding

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yongfeng [Idaho National Laboratory

    2016-09-01

    U3Si2 and FeCrAl have been proposed as fuel and cladding concepts, respectively, for accident tolerance fuels with higher tolerance to accident scenarios compared to UO2. However, a lot of key physics and material properties regarding their in-pile performance are yet to be explored. To accelerate the understanding and reduce the cost of experimental studies, multiscale modeling and simulation are used to develop physics-based materials models to assist engineering scale fuel performance modeling. In this report, the lower-length-scale efforts in method and material model development supported by the Accident Tolerance Fuel (ATF) high-impact-problem (HIP) under the NEAMS program are summarized. Significant progresses have been made regarding interatomic potential, phase field models for phase decomposition and gas bubble formation, and thermal conductivity for U3Si2 fuel, and precipitation in FeCrAl cladding. The accomplishments are very useful by providing atomistic and mesoscale tools, improving the current understanding, and delivering engineering scale models for these two ATF concepts.

  17. Modeling and simulation of the dynamic behavior of portable proton exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, C.

    2005-07-01

    In order to analyze the operational behavior, a mathematical model of planar self-breathing fuel cells is developed and validated in Chapter 3 of this thesis. The multicomponent transport of the species is considered as well as the couplings between the transport processes of heat, charge, and mass and the electrochemical reactions. Furthermore, to explain the oxygen mass transport limitation in the porous electrode of the cathode side an agglomerate model for the oxygen reduction reaction is developed. In Chapter 4 the important issue of liquid water generation and transport in PEMFCs is addressed. One of the major tasks when operating this type of fuel cell is avoiding the complete flooding of the PEMFC during operation. A one-dimensional and isothermal model is developed that is based on a coupled system of partial differential equations. The model contains a dynamic and two-phase description of the proton exchange membrane fuel cell. The mass transport in the gas phase and in the liquid phase is considered as well as the phase transition between liquid water and water vapor. The transport of charges and the electrochemical reactions are part of the model. Flooding effects that are caused by liquid water accumulation are described by this model. Moreover, the model contains a time-dependent description of the membrane that accounts for Schroeder's paradox. The model is applied to simulate cyclic voltammograms. Chapter 5 is focused on the dynamic investigation of PEMFC stacks. Understanding the dynamic behavior of fuel cell stacks is important for the operation and control of fuel cell stacks. Using the single cell model of Chapter 3 and the dynamic model of Chapter 4 as basis, a mathematical model of a PEMFC stack is developed. However, due to the complexity of a fuel cell stack, the spatial resolution and dynamic description of the liquid water transport are not accounted for. These restrictions allow for direct comparison between the solution variables of

  18. Multiple-Echo Suppression Modeling and Experimental Verification for Acoustic Transmission along Periodic Drillstring Using Dual Receivers

    Directory of Open Access Journals (Sweden)

    Li Cheng

    2014-01-01

    Full Text Available In the oil industry, the accompanied reverberation is a major constraint in the transmission rate and distance because the drillstring is a heterogeneous assembly. Based on the transient impulse responses in uplink and downlink channels, an improved simplified echo suppression model with two acoustic receivers is presented in consideration of position optimization of single acoustic receiver. Then the acoustic receiving characteristics of transmitted signals in a length-limited periodic drillstring channel are obtained in single- and dual-receiver modes. An additive downward white Gaussian noise is also introduced in the channel. Moreover, an experimental rig is established by using a rotatable electromagnetic vibration exciter and two piezoelectric accelerometers, which are spaced one-quarter wavelength apart along a 6.3-meter simulated periodic drillstring. The ASK-, FSK-, and PSK-modulated square-wave pulse sequences at a transmission rate of 200 bit/s are applied to the simulated drillstring at a rotation speed of 0, 80, and 140 r/min, respectively. The experimental results show that the dual-receiver mode can exhibit a significantly improved average error bit ratio, which is approximately 2.5 to 3 times lower than that of the single-receiver mode, especially under the conditions of higher rotation speeds.

  19. Improvement of Jet Breakup Model in Fuel Coolant Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Kwang Hyun; Kim, Kyung Kyu; Nam, Yang Ho [Korea Maritime Univ., Jinhae (Korea, Republic of)

    2007-02-15

    The objective of this work is to improve TRACER-II code in conjunction with the OECD SERENA project for validation of vapor explosion analysis codes. FCI breakup model is to be improved by building four-fluid multiphase flow model and existing models and experimental data are examined for the validation of the model. Four-fluid multiphase flow model has been built in TRACER-II code and jet breakup model has been included. Kelvin-Helmholtz instability is modelled for the jet side and boundary layer stripping is modelled for the jet leading edge. This work can contributes to the reduction of uncertainty in the FCI models for reactor safety analysis.

  20. 微生物燃料电池阴极电子受体研究进展%Progress on cathode eletron-receiver of microbial fuel cells

    Institute of Scientific and Technical Information of China (English)

    卜文辰; 蔡昌凤

    2013-01-01

    微生物燃料电池是一个阳极产生电子,阴极接受电子的电化学系统.阐述了微生物燃料电池各种电子受体在阴极的反应机理和研究现状,分析了目前微生物燃料电池研究存在的不足,并提出了未来的研究和发展方向.%Microbial fuel cell (MFC) is a electrochemical system of anode donate electrons and cathode as an accepter.This paper elaborates the reaction mechanism and research status of kinds of electron acceptors of MFC in cathode ; analysis the difference in current research in MFC,and put forward the research and development direction in future.

  1. Conformity of the time and root characteristics received at modeling of linear systems in the environment of MATLAB

    Directory of Open Access Journals (Sweden)

    Vitaliy Borodenko

    2009-10-01

    Full Text Available The author analyses conformity of the time and root characteristics received at modeling of linear systems in the environment of MATLAB, to each other and to the standard approach. The author studies conditions of reception of false or inexact results at the analysis of regulation quality on the transition characteristic.

  2. Heat and mass transfer effects in a direct methanol fuel cell: A 1D model

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, V.B.; Falcao, D.S.; Pinto, A.M.F.R. [Centro de Estudos de Fenomenos de Transporte, Departamento de Eng. Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Rangel, C.M. [INETI - Unidade de Electroquimica e Materiais, Paco do Lumiar, 22,1649-038 (Portugal)

    2008-07-15

    Models are a fundamental tool for the design process of fuel cells and fuel cell systems. In this work, a steady-state, one-dimensional model accounting for coupled heat and mass transfer, along with the electrochemical reactions occurring in the DMFC, is presented. The model output is the temperature profile through the cell and the water balance and methanol crossover between the anode and the cathode. The model predicts the correct trends for the influence of current density and methanol feed concentration on both methanol and water crossover. The model estimates the net water transfer coefficient through the membrane, {alpha}, a very important parameter to describe water management in the DMFC. Suitable operating ranges can be set up for different MEA structures maintaining the crossover of methanol and water within acceptable levels. The model is rapidly implemented and is therefore suitable for inclusion in real-time system level DMFC calculations. (author)

  3. Modeling of Heating and Evaporation of FACE I Gasoline Fuel and its Surrogates

    KAUST Repository

    Elwardani, Ahmed Elsaid

    2016-04-05

    The US Department of Energy has formulated different gasoline fuels called \\'\\'Fuels for Advanced Combustion Engines (FACE)\\'\\' to standardize their compositions. FACE I is a low octane number gasoline fuel with research octane number (RON) of approximately 70. The detailed hydrocarbon analysis (DHA) of FACE I shows that it contains 33 components. This large number of components cannot be handled in fuel spray simulation where thousands of droplets are directly injected in combustion chamber. These droplets are to be heated, broken-up, collided and evaporated simultaneously. Heating and evaporation of single droplet FACE I fuel was investigated. The heating and evaporation model accounts for the effects of finite thermal conductivity, finite liquid diffusivity and recirculation inside the droplet, referred to as the effective thermal conductivity/effective diffusivity (ETC/ED) model. The temporal variations of the liquid mass fractions of the droplet components were used to characterize the evaporation process. Components with similar evaporation characteristics were merged together. A representative component was initially chosen based on the highest initial mass fraction. Three 6 components surrogates, Surrogate 1-3, that match evaporation characteristics of FACE I have been formulated without keeping same mass fractions of different hydrocarbon types. Another two surrogates (Surrogate 4 and 5) were considered keeping same hydrocarbon type concentrations. A distillation based surrogate that matches measured distillation profile was proposed. The calculated molar mass, hydrogen-to-carbon (H/C) ratio and RON of Surrogate 4 and distillation based one are close to those of FACE I.

  4. Modeling, simulation, and concept studies of a fuel cell hybrid electric vehicle powertrain

    Energy Technology Data Exchange (ETDEWEB)

    Oezbek, Markus

    2010-03-29

    This thesis focuses on the development of a fuel cell-based hybrid electric powertrain for smaller (2 kW) hybrid electric vehicles (HEVs). A Hardware-in-the-Loop test rig is designed and built with the possibility to simulate any load profile for HEVs in a realistic environment, whereby the environment is modeled. Detailed simulation models of the test rig are developed and validated to real physical components and control algorithms are designed for the DC/DC-converters and the fuel cell system. A state-feedback controller is developed for the DC/DC-converters where the state-space averaging method is used for the development. For the fuel cells, a gain-scheduling controller based on state feedback is developed and compared to two conventional methods. The design process of an HEV with regard to a given load profile is introduced with comparison between SuperCaps and batteries. The HEV is also evaluated with an introduction to different power management concepts with regard to fuel consumption, dynamics, and fuel cell deterioration rate. The power management methods are implemented in the test rig and compared. (orig.)

  5. A model to predict failure of irradiated U–Mo dispersion fuel

    Energy Technology Data Exchange (ETDEWEB)

    Burkes, Douglas E., E-mail: Douglas.Burkes@pnnl.gov; Senor, David J.; Casella, Andrew M.

    2016-12-15

    Highlights: • Simple model to predict failure of dispersion fuel meat designs. • Evaluated as a function of fabrication parameters and irradiation conditions. • Predictions compare well with experimental measurements of miniature fuel plates. • Interaction layer formation reduces matrix strength and increases temperature. • Si additions to the matrix appear effective only at moderate heat flux and burnup. - Abstract: Numerous global programs are focused on the continued development of existing and new research and test reactor fuels to achieve maximum attainable uranium loadings to support the conversion of a number of the world’s remaining high-enriched uranium fueled reactors to low-enriched uranium fuel. Some of these programs are focused on development and qualification of a fuel design that consists of a uranium–molybdenum (U–Mo) alloy dispersed in an aluminum matrix as one option for reactor conversion. The current paper extends a failure model originally developed for UO{sub 2}-stainless steel dispersion fuels and uses currently available thermal–mechanical property information for the materials of interest in the currently proposed design. A number of fabrication and irradiation parameters were investigated to understand the conditions at which failure of the matrix, classified as onset of pore formation in the matrix, might occur. The results compared well with experimental observations published as part of the Reduced Enrichment for Research and Test Reactors (RERTR)-6 and -7 mini-plate experiments. Fission rate, a function of the {sup 235}U enrichment, appeared to be the most influential parameter in premature failure, mainly as a result of increased interaction layer formation and operational temperature, which coincidentally decreased the strength of the matrix and caused more rapid fission gas production and recoil into the surrounding matrix material. Addition of silicon to the matrix appeared effective at reducing the rate of

  6. Manual of phosphoric acid fuel cell stack three-dimensional model and computer program

    Science.gov (United States)

    Lu, C. Y.; Alkasab, K. A.

    1984-01-01

    A detailed distributed mathematical model of phosphoric acid fuel cell stack have been developed, with the FORTRAN computer program, for analyzing the temperature distribution in the stack and the associated current density distribution on the cell plates. Energy, mass, and electrochemical analyses in the stack were combined to develop the model. Several reasonable assumptions were made to solve this mathematical model by means of the finite differences numerical method.

  7. Non-linear model reduction and control of molten carbonate fuel cell systems with internal reforming

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, Min

    2007-10-12

    Currently, the process design of fuel cells and the development of control strategies is mainly based on heuristic methods. Fuel cell models are often too complex for control purposes, or they are developed for a specific type of fuel cell and valid only in a small range of operation conditions. The application of fuel cell models to controller design is still limited. Furthermore, suitable and simple-to-implement design strategies for fuel cell control remain an open area. There is thus a motivation for simplifying dynamic models for process control applications and for designing suitable control strategies for fuel cells. This is the main objective of this work. As an application example, the 250 kW industrial molten carbonate fuel cell (MCFC) system HotModule by MTU CFC Solutions, Germany is considered. A detailed dynamic two-dimensional spatially distributed cross-flow model of a MCFC from literature is taken as a starting point for the investigation. In Chapter 2, two simplified model versions are derived by incorporating additional physical assumptions. One of the simplified models is extended to a three-dimensional stack model to deal with physical and chemical phenomena in the stack. Simulations of the stack model are performed in Chapter 3 in order to calculate the mass and temperature distributions in the direction perpendicular to the electrode area. The other simplified model forms the basis for a low order reduced model that is derived in Chapter 4. The reduced-order model is constructed by application of the Karhunen-Loeve Galerkin method. The spatial temperature, concentration and potential profiles are approximated by a set of orthogonal time independent spatial basis functions. Problem specific basis functions are generated numerically from simulation data of the detailed reference model. The advantage of this approach is that a small number of basis functions suffices in order to approximate the solution of the detailed model very well. The

  8. Dynamic Modeling of a Reformed Methanol Fuel Cell System using Empirical Data and Adaptive Neuro-Fuzzy Inference System Models

    DEFF Research Database (Denmark)

    Justesen, Kristian Kjær; Andreasen, Søren Juhl; Shaker, Hamid Reza

    2014-01-01

    In this work, a dynamic MATLAB Simulink model of a H3-350 Reformed Methanol Fuel Cell (RMFC) stand-alone battery charger produced by Serenergy is developed on the basis of theoretical and empirical methods. The advantage of RMFC systems is that they use liquid methanol as a fuel instead of gaseous...... of the reforming process are implemented. Models of the cooling flow of the blowers for the fuel cell and the burner which supplies process heat for the reformer are made. The two blowers have a common exhaust, which means that the two blowers influence each other’s output. The models take this into account using...... an empirical approach. Fin efficiency models for the cooling effect of the air are also developed using empirical methods. A fuel cell model is also implemented based on a standard model which is adapted to fit the measured performance of the H3-350 module. All the individual parts of the model are verified...

  9. Dynamic Modeling of a Reformed Methanol Fuel Cell System using Empirical Data and Adaptive Neuro-Fuzzy Inference System Models

    DEFF Research Database (Denmark)

    Justesen, Kristian Kjær; Andreasen, Søren Juhl; Shaker, Hamid Reza

    2013-01-01

    In this work, a dynamic MATLAB Simulink model of a H3-350 Reformed Methanol Fuel Cell (RMFC) stand-alone battery charger produced by Serenergy is developed on the basis of theoretical and empirical methods. The advantage of RMFC systems is that they use liquid methanol as a fuel instead of gaseous...... of the reforming process are implemented. Models of the cooling flow of the blowers for the fuel cell and the burner which supplies process heat for the reformer are made. The two blowers have a common exhaust, which means that the two blowers influence each other’s output. The models take this into account using...... an empirical approach. Fin efficiency models for the cooling effect of the air are also developed using empirical methods. A fuel cell model is also implemented based on a standard model which is adapted to fit the measured performance of the H3-350 module. All the individual parts of the model are verified...

  10. Modeling the reaction kinetics of a hydrogen generator onboard a fuel cell -- Electric hybrid motorcycle

    Science.gov (United States)

    Ganesh, Karthik

    Owing to the perceived decline of the fossil fuel reserves in the world and environmental issues like pollution, conventional fuels may be replaced by cleaner alternative fuels. The potential of hydrogen as a fuel in vehicular applications is being explored. Hydrogen as an energy carrier potentially finds applications in internal combustion engines and fuel cells because it is considered a clean fuel and has high specific energy. However, at 6 to 8 per kilogram, not only is hydrogen produced from conventional methods like steam reforming expensive, but also there are storage and handling issues, safety concerns and lack of hydrogen refilling stations across the country. The purpose of this research is to suggest a cheap and viable system that generates hydrogen on demand through a chemical reaction between an aluminum-water slurry and an aqueous sodium hydroxide solution to power a 2 kW fuel cell on a fuel cell hybrid motorcycle. This reaction is essentially an aluminum-water reaction where sodium hydroxide acts as a reaction promoter or catalyst. The Horizon 2000 fuel cell used for this purpose has a maximum hydrogen intake rate of 28 lpm. The study focuses on studying the exothermic reaction between the reactants and proposes a rate law that best describes the rate of generation of hydrogen in connection to the surface area of aluminum available for the certain reaction and the concentration of the sodium hydroxide solution. Further, the proposed rate law is used in the simulation model of the chemical reactor onboard the hybrid motorcycle to determine the hydrogen flow rate to the fuel cell with time. Based on the simulated rate of production of hydrogen from the chemical system, its feasibility of use on different drive cycles is analyzed. The rate of production of hydrogen with a higher concentration of sodium hydroxide and smaller aluminum powder size was found to enable the installation of the chemical reactor on urban cycles with frequent stops and starts

  11. Starch hydrolysis modeling: application to fuel ethanol production.

    Science.gov (United States)

    Murthy, Ganti S; Johnston, David B; Rausch, Kent D; Tumbleson, M E; Singh, Vijay

    2011-09-01

    Efficiency of the starch hydrolysis in the dry grind corn process is a determining factor for overall conversion of starch to ethanol. A model, based on a molecular approach, was developed to simulate structure and hydrolysis of starch. Starch structure was modeled based on a cluster model of amylopectin. Enzymatic hydrolysis of amylose and amylopectin was modeled using a Monte Carlo simulation method. The model included the effects of process variables such as temperature, pH, enzyme activity and enzyme dose. Pure starches from wet milled waxy and high-amylose corn hybrids and ground yellow dent corn were hydrolyzed to validate the model. Standard deviations in the model predictions for glucose concentration and DE values after saccharification were less than ± 0.15% (w/v) and ± 0.35%, respectively. Correlation coefficients for model predictions and experimental values were 0.60 and 0.91 for liquefaction and 0.84 and 0.71 for saccharification of amylose and amylopectin, respectively. Model predictions for glucose (R2 = 0.69-0.79) and DP4+ (R2 = 0.8-0.68) were more accurate than the maltotriose and maltose for hydrolysis of high-amylose and waxy corn starch. For yellow dent corn, simulation predictions for glucose were accurate (R2 > 0.73) indicating that the model can be used to predict the glucose concentrations during starch hydrolysis.

  12. Gas composition modeling in a reformed Methanol Fuel Cell system using adaptive Neuro-Fuzzy Inference Systems

    DEFF Research Database (Denmark)

    Justesen, Kristian Kjær; Andreasen, Søren Juhl; Shaker, Hamid Reza

    2013-01-01

    This work presents a method for modeling the gas composition in a Reformed Methanol Fuel Cell system. The method is based on Adaptive Neuro-Fuzzy-Inference-Systems which are trained on experimental data. The developed models are of the H2, CO2, CO and CH3OH mass flows of the reformed gas. The ANFIS......, or fuel cell diagnostics systems....

  13. Experimental study and modeling of degradation phenomena in HTPEM fuel cell stacks for use in CHP systems

    DEFF Research Database (Denmark)

    Nielsen, Mads Pagh; Andreasen, Søren Juhl; Rasmussen, Peder Lund

    2009-01-01

    Degradation phenomena in HTPEM fuel cells for use in CHP systems were investigated experimentally and by modeling. It was found that the two main degradation mechanisms in HTPEM fuel cells are carbon corrosion and Pt agglomeration. On basis of this conclusion a mechanistic model, describing...

  14. Experimental study and modelling of degradation phenomena in HTPEM fuel cell stacks for use in CHP systems

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl

    2009-01-01

    Degradation phenomena in HTPEM fuel cells for use in CHP systems were investigated experimentally and by modelling. It was found that the two main degradation mechanisms in HTPEM fuel cells are carbon corrosion and Pt agglomeration. On basis of this conclusion a mechanistic model, describing...

  15. Water balance simulations of a polymer-electrolyte membrane fuel cell using a two-fluid model

    DEFF Research Database (Denmark)

    Berning, Torsten; Odgaard, M.; Kær, Søren Knudsen

    2011-01-01

    A previously published computational multi-phase model of a polymer-electrolyte membrane fuel cell cathode has been extended in order to account for the anode side and the electrolyte membrane. The model has been applied to study the water balance of a fuel cell during operation under various hum...

  16. The program cyberdiesel for mathematical modeling of fuel supply and local intracylinder processes in a diesel engine with volumetric carburetion

    OpenAIRE

    Maschenko, V. Yu.

    2007-01-01

    The program CyberDiesel is developed on the basis of complex mathematical model of fuel supply and local intracylinder processes in a diesel engine with volumetric carburetion. The program is intended for solving practical problems of coordinating constructive and adjusting parameters of fuel equipment and combustion chamber of a diesel engine by mathematical modeling methods.

  17. Relative importance of fuel management, ignition management and weather for area burned: Evidence from five landscape-fire-succession models

    Science.gov (United States)

    Geoffrey J. Cary; Mike D. Flannigan; Robert E. Keane; Ross A. Bradstock; Ian D. Davies; James M. Lenihan; Chao Li; Kimberley A. Logan; Russell A. Parsons

    2009-01-01

    The behaviour of five landscape fire models (CAFE, FIRESCAPE, LAMOS(HS), LANDSUM and SEMLAND) was compared in a standardised modelling experiment. The importance of fuel management approach, fuel management effort, ignition management effort and weather in determining variation in area burned and number of edge pixels burned (a measure of potential impact on assets...

  18. An evaluation of hardwood fuel models for planning prescribed fires in oak shelterwood stands

    Science.gov (United States)

    Patrick H. Brose

    2017-01-01

    The shelterwood burn technique is becoming more accepted and used as a means of regenerating eastern mixed-oak (Quercus spp.) forests on productive upland sites. Preparation is important to successfully implement this method; part of that preparation is selecting the proper fuel model (FM) for the prescribed fire. Because of the mix of leaf litter...

  19. An Economic Model of Brazil’s Ethanol-Sugar Markets and Impacts of Fuel Policies

    NARCIS (Netherlands)

    Drabik, D.; Gorter, de H.; Just, D.R.; Timilsina, G.R.

    2014-01-01

    We develop an economic model of flex plants, export demands and two domestic fuel demand curves: E25, a 25 percent blend of ethanol with gasoline consumed by conventional cars, and E100, ethanol consumed only by flex cars. This allows us to analyze the market impacts of specific policies, namely the

  20. Water equilibria and management using a two-volume model of a polymer electrolyte fuel cell

    Science.gov (United States)

    Karnik, Amey Y.; Stefanopoulou, Anna G.; Sun, Jing

    In this paper, we introduce a modified interpretation of the water activity presented in Springer et al. [T.E. Springer, T.A. Zawodzinski, S. Gottesfeld, Polymer electrolyte fuel cell model, J. Electrochem. Soc. 138 (8) (1991) 2334-2342]. The modification directly affects the membrane water transport between the anode and the cathode (two electrodes) of the polymer electrolyte membrane (PEM) fuel cell in the presence of liquid water inside the stack. The modification permits calibration of a zero-dimensional isothermal model to predict the flooding and drying conditions in the two electrodes observed at various current levels [D. Spernjak, S. Advani, A.K. Prasad, Experimental investigation of liquid water formation and transport in a transparent single-serpentine PEM fuel cell, in: Proceedings of the Fourth International Conference on Fuel Cell Science, Engineering and Technology (FUELCELL2006-97271), June 2006]. Using this model the equilibria of the lumped water mass in the two electrodes are analyzed at various flow conditions of the stack to determine stable and unstable (liquid water growth) operating conditions. Two case studies of water management through modification of cathode inlet humidification and anode water removal are then evaluated using this model. The desired anode water removal and the desired cathode inlet humidification are specified based upon (i) the water balance requirements, (ii) the desired conditions in the electrodes, and (iii) the maximum membrane transport at those conditions.

  1. National Aviation Fuel Scenario Analysis Program (NAFSAP). Volume I. Model Description. Volume II. User Manual.

    Science.gov (United States)

    1980-03-01

    TESI CHART NATIONAI RUREAt (F ANDA[)Rt 1V4 A NATIONAL. AVIATION ~ FUEL SCENARIO.. ANALYSIS PROGRAM 49!! VOLUM I: MODEL DESCRIA~v 4<C VOLUME II: tr)ER...executes post processor which translates results of the graphics program to machine readable code used by the pen plotter) cr (depressing the carriage

  2. Synthesis of Multiwalled Carbon Nanotubes-Titania Nanomaterial for Desulfurization of Model Fuel

    Directory of Open Access Journals (Sweden)

    Tawfik A. Saleh

    2014-01-01

    Full Text Available This work reported on the development of novel nanomaterials of multiwalled carbon nanotubes doped with titania (CNT/TiO2 for the adsorptive desulfurization of model fuel oils. Various analytical techniques such as field emission scanning electron microscope (FESEM, energy dispersive X-ray spectroscopy (EDX, and Fourier transform infrared spectroscopy (FTIR were used for the characterization of the nanomaterials. The initial results indicated the effectiveness of the prepared CNT/TiO2 nanomaterials in removing sulfur compounds from model fuel oil. The adsorption of DBT, BT, and thiophene from model fuel onto the derived sorbents was performed using batch mode system. These CNT/TiO2 nanomaterials initially afforded approximately 45% removal of DBT, 55% BT, and more than 65% thiophene compounds from model fuels. The CNT/TiO2 nanomaterials provided an excellent activity towards interaction with organosulfur compounds. More experiments are underway to optimize the parameters for the adsorptive desulfurization processes. We believe that these nanomaterials as adsorbents will find useful applications in petroleum industry because of their operational simplicity, high efficiency, and high capacity.

  3. Simulations and measurements of adiabatic annular flows in triangular, tight lattice nuclear fuel bundle model

    Energy Technology Data Exchange (ETDEWEB)

    Saxena, Abhishek, E-mail: asaxena@lke.mavt.ethz.ch [ETH Zurich, Laboratory for Nuclear Energy Systems, Department of Mechanical and Process Engineering, Sonneggstrasse 3, 8092 Zürich (Switzerland); Zboray, Robert [Laboratory for Thermal-hydraulics, Nuclear Energy and Safety Department, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland); Prasser, Horst-Michael [ETH Zurich, Laboratory for Nuclear Energy Systems, Department of Mechanical and Process Engineering, Sonneggstrasse 3, 8092 Zürich (Switzerland); Laboratory for Thermal-hydraulics, Nuclear Energy and Safety Department, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland)

    2016-04-01

    High conversion light water reactors (HCLWR) having triangular, tight-lattice fuels bundles could enable improved fuel utilization compared to present day LWRs. However, the efficient cooling of a tight lattice bundle has to be still proven. Major concern is the avoidance of high-quality boiling crisis (film dry-out) by the use of efficient functional spacers. For this reason, we have carried out experiments on adiabatic, air-water annular two-phase flows in a tight-lattice, triangular fuel bundle model using generic spacers. A high-spatial-resolution, non-intrusive measurement technology, cold neutron tomography, has been utilized to resolve the distribution of the liquid film thickness on the virtual fuel pin surfaces. Unsteady CFD simulations have also been performed to replicate and compare with the experiments using the commercial code STAR-CCM+. Large eddies have been resolved on the grid level to capture the dominant unsteady flow features expected to drive the liquid film thickness distribution downstream of a spacer while the subgrid scales have been modeled using the Wall Adapting Local Eddy (WALE) subgrid model. A Volume of Fluid (VOF) method, which directly tracks the interface and does away with closure relationship models for interfacial exchange terms, has also been employed. The present paper shows first comparison of the measurement with the simulation results.

  4. A study of the diffusion of alternative fuel vehicles : An agent-based modeling approach

    NARCIS (Netherlands)

    Zhang, Ting; Gensler, Sonja; Garcia, Rosanna

    This paper demonstrates the use of an agent-based model (ABM) to investigate factors that can speed the diffusion of eco-innovations, namely alternative fuel vehicles (AFVs). The ABM provides the opportunity to consider the interdependencies inherent between key participants in the automotive

  5. Dynamic Thermal Model and Temperature Control of Proton Exchange Membrane Fuel Cell Stack

    Institute of Scientific and Technical Information of China (English)

    邵庆龙; 卫东; 曹广益; 朱新坚

    2005-01-01

    A dynamic thermal transfer model of a proton exchange membrane fuel cell (PEMFC) stack is developed based on energy conservation in order to reach better temperature control of PEMFC stack. Considering its uncertain parameters and disturbance, we propose a robust adaptive controller based on backstepping algorithm of Lyaponov function. Numerical simulations indicate the validity of the proposed controller.

  6. Contact behavior modelling and its size effect on proton exchange membrane fuel cell

    Science.gov (United States)

    Qiu, Diankai; Peng, Linfa; Yi, Peiyun; Lai, Xinmin; Janßen, Holger; Lehnert, Werner

    2017-10-01

    Contact behavior between the gas diffusion layer (GDL) and bipolar plate (BPP) is of significant importance for proton exchange membrane fuel cells. Most current studies on contact behavior utilize experiments and finite element modelling and focus on fuel cells with graphite BPPs, which lead to high costs and huge computational requirements. The objective of this work is to build a more effective analytical method for contact behavior in fuel cells and investigate the size effect resulting from configuration alteration of channel and rib (channel/rib). Firstly, a mathematical description of channel/rib geometry is outlined in accordance with the fabrication of metallic BPP. Based on the interface deformation characteristic and Winkler surface model, contact pressure between BPP and GDL is then calculated to predict contact resistance and GDL porosity as evaluative parameters of contact behavior. Then, experiments on BPP fabrication and contact resistance measurement are conducted to validate the model. The measured results demonstrate an obvious dependence on channel/rib size. Feasibility of the model used in graphite fuel cells is also discussed. Finally, size factor is proposed for evaluating the rule of size effect. Significant increase occurs in contact resistance and porosity for higher size factor, in which channel/rib width decrease.

  7. Fuel treatment effects on modeled landscape level fire behavior in the northern Sierra Nevada

    Science.gov (United States)

    J.J. Moghaddas; B.M. Collins; K. Menning; E.E.Y. Moghaddas; S.L. Stephens

    2010-01-01

    Across the western United States, decades of fire exclusion combined with past management history have contributed to the current condition of extensive areas of high-density, shade-tolerant coniferous stands that are increasingly prone to high-severity fires. Here, we report the modeled effects of constructed defensible fuel profile zones and group selection...

  8. Linking 3D spatial models of fuels and fire: Effects of spatial heterogeneity on fire behavior

    Science.gov (United States)

    Russell A. Parsons; William E. Mell; Peter McCauley

    2011-01-01

    Crownfire endangers fire fighters and can have severe ecological consequences. Prediction of fire behavior in tree crowns is essential to informed decisions in fire management. Current methods used in fire management do not address variability in crown fuels. New mechanistic physics-based fire models address convective heat transfer with computational fluid dynamics (...

  9. A simple numerical model to estimate the effect of coal selection on pulverized fuel burnout

    Energy Technology Data Exchange (ETDEWEB)

    Sun, J.K.; Hurt, R.H.; Niksa, S.; Muzio, L.; Mehta, A.; Stallings, J. [Brown University, Providence, RI (USA). Division Engineering

    2003-06-01

    The amount of unburned carbon in ash is an important performance characteristic in commercial boilers fired with pulverized coal. Unburned carbon levels are known to be sensitive to fuel selection, and there is great interest in methods of estimating the burnout propensity of coals based on proximate and ultimate analysis - the only fuel properties readily available to utility practitioners. A simple numerical model is described that is specifically designed to estimate the effects of coal selection on burnout in a way that is useful for commercial coal screening. The model is based on a highly idealized description of the combustion chamber but employs detailed descriptions of the fundamental fuel transformations. The model is validated against data from laboratory and pilot-scale combustors burning a range of international coals, and then against data obtained from full-scale units during periods of coal switching. The validated model form is then used in a series of sensitivity studies to explore the role of various individual fuel properties that influence burnout.

  10. An Economic Model of Brazil’s Ethanol-Sugar Markets and Impacts of Fuel Policies

    NARCIS (Netherlands)

    Drabik, D.; Gorter, de H.; Just, D.R.; Timilsina, G.R.

    2014-01-01

    We develop an economic model of flex plants, export demands and two domestic fuel demand curves: E25, a 25 percent blend of ethanol with gasoline consumed by conventional cars, and E100, ethanol consumed only by flex cars. This allows us to analyze the market impacts of specific policies, namely the

  11. Development of a used fuel cladding damage model incorporating circumferential and radial hydride responses

    Science.gov (United States)

    Chen, Qiushi; Ostien, Jakob T.; Hansen, Glen

    2014-04-01

    At the completion of the fuel drying process, used fuel Zry4 cladding typically exhibits a significant population of δ-hydride inclusions. These inclusions are in the form of small platelets that are generally oriented both circumferentially and radially within the cladding material. There is concern that radially-oriented hydride inclusions may weaken the cladding material and lead to issues during used fuel storage and transportation processes. A high fidelity model of the mechanical behavior of hydrides has utility in both designing fuel cladding to be more resistant to this hydride-induced weakening and also in suggesting modifications to drying, storage, and transport operations to reduce the impact of hydride formation and/or the avoidance of loading scenarios that could overly stress the radial inclusions. We develop a mechanical model for the Zry4-hydride system that, given a particular morphology of hydride inclusions, allows the calculation of the response of the hydrided cladding under various loading scenarios. The model treats the Zry4 matrix material as J2 elastoplastic, and treats the hydrides as platelets oriented in predefined directions (e.g., circumferentially and radially). The model is hosted by the Albany analysis framework, where a finite element approximation of the weak form of the cladding boundary value problem is solved using a preconditioned Newton-Krylov approach. Instead of forming the required system Jacobian operator directly or approximating its action with a differencing operation, Albany leverages the Trilinos Sacado package to form the Jacobian via automatic differentiation. We present results that describe the performance of the model in comparison with as-fabricated Zry4 as well as HB Robinson fuel cladding. Further, we also present performance results that demonstrate the efficacy of the overall solution method employed to host the model.

  12. Development of a used fuel cladding damage model incorporating circumferential and radial hydride responses

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qiushi, E-mail: qiushi@clemson.edu [Glenn Department of Civil Engineering, Clemson University, Clemson, SC 29634 (United States); Ostien, Jakob T., E-mail: jtostie@sandia.gov [Mechanics of Materials Dept. 8256, Sandia National Laboratories, P.O. Box 969, Livermore, CA 94551-0969 (United States); Hansen, Glen, E-mail: gahanse@sandia.gov [Computational Multiphysics Dept. 1443, Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185-1321 (United States)

    2014-04-01

    At the completion of the fuel drying process, used fuel Zry4 cladding typically exhibits a significant population of δ-hydride inclusions. These inclusions are in the form of small platelets that are generally oriented both circumferentially and radially within the cladding material. There is concern that radially-oriented hydride inclusions may weaken the cladding material and lead to issues during used fuel storage and transportation processes. A high fidelity model of the mechanical behavior of hydrides has utility in both designing fuel cladding to be more resistant to this hydride-induced weakening and also in suggesting modifications to drying, storage, and transport operations to reduce the impact of hydride formation and/or the avoidance of loading scenarios that could overly stress the radial inclusions. We develop a mechanical model for the Zry4-hydride system that, given a particular morphology of hydride inclusions, allows the calculation of the response of the hydrided cladding under various loading scenarios. The model treats the Zry4 matrix material as J{sub 2} elastoplastic, and treats the hydrides as platelets oriented in predefined directions (e.g., circumferentially and radially). The model is hosted by the Albany analysis framework, where a finite element approximation of the weak form of the cladding boundary value problem is solved using a preconditioned Newton–Krylov approach. Instead of forming the required system Jacobian operator directly or approximating its action with a differencing operation, Albany leverages the Trilinos Sacado package to form the Jacobian via automatic differentiation. We present results that describe the performance of the model in comparison with as-fabricated Zry4 as well as HB Robinson fuel cladding. Further, we also present performance results that demonstrate the efficacy of the overall solution method employed to host the model.

  13. Two dimensional, two fluid model for sodium boiling in LMFBR fuel assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Granziera, M.R.; Kazimi, M.S.

    1980-05-01

    A two dimensional numerical model for the simulation of sodium boiling transient was developed using the two fluid set of conservation equations. A semiimplicit numerical differencing scheme capable of handling the problems associated with the ill-posedness implied by the complex characteristic roots of the two fluid problems was used, which took advantage of the dumping effect of the exchange terms. Of particular interest in the development of the model was the identification of the numerical problems caused by the strong disparity between the axial and radial dimensions of fuel assemblies. A solution to this problem was found which uses the particular geometry of fuel assemblies to accelerate the convergence of the iterative technique used in the model. Three sodium boiling experiments were simulated with the model, with good agreement between the experimental results and the model predictions.

  14. Modeled and experimental results of an omnidirectional free-space optical receiver architecture

    Science.gov (United States)

    Murshid, Syed H.; Lovell, Gregory L.; Finch, Michael F.

    2017-03-01

    Free-space optical (FSO) communications provide point-to-point connectivity while offering many advantages in size, weight, and power as compared to radio frequency. It has the potential to provide fiber-optic data rates without the need for lengthy fiber cables. Omnidirectional FSO, also known as O-FSO systems, provide a non-line-of-sight option for data communications. They are gaining popularity in short-distance networks. Most existing O-FSO links range from 1 to 100 m and present experimental/simulated data rates ranging between 5 kb/s and 1 Mb/s. A 2.5-Gb/s O-FSO system was recently reported with a range of 25 cm. This paper employs a fiber bundle as an O-FSO receiver. The energy collected by the receiver is related to the acceptance cone of each fiber. The fiber bundle integrates the optical power gathered by the individual fibers and couples it to the photodetector. Experimental data rates approaching 100 kb/s over a meter long system are presented, whereas simulated results support a data rate up to 52 Mb/s for distances approaching a kilometer. Theoretical and experimental optical power versus range is also presented for the proposed O-FSO architecture, using on-off keying.

  15. GPS receivers timing data processing using neural networks: optimal estimation and errors modeling.

    Science.gov (United States)

    Mosavi, M R

    2007-10-01

    The Global Positioning System (GPS) is a network of satellites, whose original purpose was to provide accurate navigation, guidance, and time transfer to military users. The past decade has also seen rapid concurrent growth in civilian GPS applications, including farming, mining, surveying, marine, and outdoor recreation. One of the most significant of these civilian applications is commercial aviation. A stand-alone civilian user enjoys an accuracy of 100 meters and 300 nanoseconds, 25 meters and 200 nanoseconds, before and after Selective Availability (SA) was turned off. In some applications, high accuracy is required. In this paper, five Neural Networks (NNs) are proposed for acceptable noise reduction of GPS receivers timing data. The paper uses from an actual data collection for evaluating the performance of the methods. An experimental test setup is designed and implemented for this purpose. The obtained experimental results from a Coarse Acquisition (C/A)-code single-frequency GPS receiver strongly support the potential of methods to give high accurate timing. Quality of the obtained results is very good, so that GPS timing RMS error reduce to less than 120 and 40 nanoseconds, with and without SA.

  16. Mathematical modelling of friction-vibration interactions of nuclear fuel rods

    Directory of Open Access Journals (Sweden)

    Zeman V.

    2016-06-01

    Full Text Available Nuclear fuel rods (FRs are transverselly linked to each other by three spacer grid cells at several vertical levels inside a fuel assembly (FA. Vibration of FA components, caused by the motion of FA support plates in the reactor core, generates variable contact forces between FRs and spacer grid cells. Friction effects in contact surfaces have an influence on the expected lifetime period of nuclear FA in terms of FR cladding fretting wear. This paper introduces an original approach to mathematical modelling and simulation analysis of FR nonlinear vibrations and fretting wear taking into consideration friction forces at all levels of spacer grids.

  17. Redox Chemistry in Radiation Induced Dissolution of Spent Nuclear Fuel : from Elementary Reactions to Predictive Modeling

    OpenAIRE

    Roth, Olivia

    2008-01-01

    The focus of this doctoral thesis is the redox chemistry involved in radiation induced oxidative dissolution of spent nuclear fuel and UO2 (as a model substance for spent nuclear fuel). It is shown that two electron oxidants are more efficient than one electron oxidants in oxidative dissolution of UO2 at low oxidant concentrations. Furthermore, it is shown that H2O2 is the only oxidant that has to be taken into account in radiation induced dissolution of UO2 under deep repository conditions (...

  18. Soot modeling of counterflow diffusion flames of ethylene-based binary mixture fuels

    KAUST Repository

    Wang, Yu

    2015-03-01

    A soot model was developed based on the recently proposed PAH growth mechanism for C1-C4 gaseous fuels (KAUST PAH Mechanism 2, KM2) that included molecular growth up to coronene (A7) to simulate soot formation in counterflow diffusion flames of ethylene and its binary mixtures with methane, ethane and propane based on the method of moments. The soot model has 36 soot nucleation reactions from 8 PAH molecules including pyrene and larger PAHs. Soot surface growth reactions were based on a modified hydrogen-abstraction-acetylene-addition (HACA) mechanism in which CH3, C3H3 and C2H radicals were included in the hydrogen abstraction reactions in addition to H atoms. PAH condensation on soot particles was also considered. The experimentally measured profiles of soot volume fraction, number density, and particle size were well captured by the model for the baseline case of ethylene along with the cases involving mixtures of fuels. The simulation results, which were in qualitative agreement with the experimental data in the effects of binary fuel mixing on the sooting structures of the measured flames, showed in particular that 5% addition of propane (ethane) led to an increase in the soot volume fraction of the ethylene flame by 32% (6%), despite the fact that propane and ethane are less sooting fuels than is ethylene, which is in reasonable agreement with experiments of 37% (14%). The model revealed that with 5% addition of methane, there was an increase of 6% in the soot volume fraction. The average soot particle sizes were only minimally influenced while the soot number densities were increased by the fuel mixing. Further analysis of the numerical data indicated that the chemical cross-linking effect between ethylene and the dopant fuels resulted in an increase in PAH formation, which led to higher soot nucleation rates and therefore higher soot number densities. On the other hand, the rates of soot surface growth per unit surface area through the HACA mechanism were

  19. Dynamic Model of the High Temperature Proton Exchange Membrane Fuel Cell Stack Temperature

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2009-01-01

    consists of a prototype cathode air cooled 30 cell HTPEM fuel cell stack developed at the Institute of Energy Technology at Aalborg University. This fuel cell stack uses PEMEAS Celtec P-1000 membranes and runs on pure hydrogen in a dead-end anode configuration with a purge valve. The cooling of the stack...... elements for start-up, heat conduction through stack insulation, cathode air convection, and heating of the inlet gases in the manifold. Various measurements are presented to validate the model predictions of the stack temperatures....

  20. Physical-Mathematical Model for Fixed-Bed Solid Fuel Gasification Process Simulation

    Directory of Open Access Journals (Sweden)

    Slyusarskiy Konstantin V.

    2017-01-01

    Full Text Available Phycial-mathmatical model for fixed-bed coal gasification process simulation is proposed. The heterogeneous carbon oxidation chemical reactions were simulated via Arrhenius equation while homogeneous reactions in gas phase were calculated using Gibbs free energy minimization procedure. The syngas component concentration field and fuel conversion distribution as well as syngas final temperature and composition were defined for fixed bed gasification of T-grade coal of Kuznetskiy deposit. The optimal fuel residence time and gasifyer specific productivity were defined. The prevail reactions in oxidizing and reduction zones together with its height were defined.

  1. Proton exchange membrane fuel cells modeling based on artificial neural networks

    Institute of Scientific and Technical Information of China (English)

    Yudong Tian; Xinjian Zhu; Guangyi Cao

    2005-01-01

    To understand the complexity of the mathematical models of a proton exchange membrane fuel cell (PEMFC) and their shortage of practical PEMFC control, the PEMFC complex mechanism and the existing PEMFC models are analyzed, and artificial neural networks based PEMFC modeling is advanced. The structure, algorithm, training and simulation of PEMFC modeling based on improved BP networks are given out in detail. The computer simulation and conducted experiment verify that this model is fast and accurate, and can be used as a suitable operational model for PEMFC real-time control.

  2. Model documentation, Renewable Fuels Module of the National Energy Modeling System

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-01-01

    This report documents the objectives, analytical approach, and design of the National Energy Modeling System (NEMS) Renewable Fuels Module (RFM) as it relates to the production of the Annual Energy Outlook 1998 (AEO98) forecasts. The report catalogues and describes modeling assumptions, computational methodologies, data inputs, and parameter estimation techniques. A number of offline analyses used in lieu of RFM modeling components are also described. For AEO98, the RFM was modified in three principal ways, introducing capital cost elasticities of supply for new renewable energy technologies, modifying biomass supply curves, and revising assumptions for use of landfill gas from municipal solid waste (MSW). In addition, the RFM was modified in general to accommodate projections beyond 2015 through 2020. Two supply elasticities were introduced, the first reflecting short-term (annual) cost increases from manufacturing, siting, and installation bottlenecks incurred under conditions of rapid growth, and the second reflecting longer term natural resource, transmission and distribution upgrade, and market limitations increasing costs as more and more of the overall resource is used. Biomass supply curves were also modified, basing forest products supplies on production rather than on inventory, and expanding energy crop estimates to include states west of the Mississippi River using information developed by the Oak Ridge National Laboratory. Finally, for MSW, several assumptions for the use of landfill gas were revised and extended.

  3. Modelling of iodine-induced stress corrosion cracking in CANDU fuel

    Science.gov (United States)

    Lewis, B. J.; Thompson, W. T.; Kleczek, M. R.; Shaheen, K.; Juhas, M.; Iglesias, F. C.

    2011-01-01

    Iodine-induced stress corrosion cracking (I-SCC) is a recognized factor for fuel-element failure in the operation of nuclear reactors requiring the implementation of mitigation measures. I-SCC is believed to depend on certain factors such as iodine concentration, oxide layer type and thickness on the fuel sheath, irradiation history, metallurgical parameters related to sheath like texture and microstructure, and the mechanical properties of zirconium alloys. This work details the development of a thermodynamics and mechanistic treatment accounting for the iodine chemistry and kinetics in the fuel-to-sheath gap and its influence on I-SCC phenomena. The governing transport equations for the model are solved with a finite-element technique using the COMSOL Multiphysics® commercial software platform. Based on this analysis, this study also proposes potential remedies for I-SCC.

  4. Modeling Methodologies for Design and Control of Solid Oxide Fuel Cell APUs

    Science.gov (United States)

    Pianese, C.; Sorrentino, M.

    2009-08-01

    Among the existing fuel cell technologies, Solid Oxide Fuel Cells (SOFC) are particularly suitable for both stationary and mobile applications, due to their high energy conversion efficiencies, modularity, high fuel flexibility, low emissions and noise. Moreover, the high working temperatures enable their use for efficient cogeneration applications. SOFCs are entering in a pre-industrial era and a strong interest for designing tools has growth in the last years. Optimal system configuration, components sizing, control and diagnostic system design require computational tools that meet the conflicting needs of accuracy, affordable computational time, limited experimental efforts and flexibility. The paper gives an overview on control-oriented modeling of SOFC at both single cell and stack level. Such an approach provides useful simulation tools for designing and controlling SOFC-APUs destined to a wide application area, ranging from automotive to marine and airplane APUs.

  5. Importance of pressure gradient in solid oxide fuel cell electrodes for modeling study

    Science.gov (United States)

    Ni, Meng; Leung, Dennis Y. C.; Leung, Michael K. H.

    The pressure gradients in the electrodes of a solid oxide fuel cell (SOFC) are frequently neglected without any justification in calculating the concentration overpotentials of the SOFC electrodes in modeling studies. In this short communication, a comparative study has been conducted to study the effect of pressure gradients on mass transfer and the resulting concentration overpotentials of an SOFC running on methane (CH 4) fuel. It is found that the pressure gradients in both anode and cathode are significant in the fuel cell electrochemical activities. Neglecting the anode pressure gradient in the calculation can lead to underestimation of the concentration overpotential by about 20% at a typical current density of 5000 A m -2 and at a temperature of 1073 K. The deviation can be even larger at a higher temperature. At the cathode, neglecting the pressure gradient can result in overestimation of the concentration overpotential by about 10% under typical working conditions.

  6. Modeling of the heat transfer performance of plate-type dispersion nuclear fuel elements

    Science.gov (United States)

    Ding, Shurong; Huo, Yongzhong; Yan, XiaoQing

    2009-08-01

    Considering the mutual actions between fuel particles and the metal matrix, the three-dimensional finite element models are developed to simulate the heat transfer behaviors of dispersion nuclear fuel plates. The research results indicate that the temperatures of the fuel plate might rise more distinctly with considering the particle swelling and the degraded surface heat transfer coefficients with increasing burnup; the local heating phenomenon within the particles appears when their thermal conductivities are too low. With rise of the surface heat transfer coefficients, the temperatures within the fuel plate decrease; the temperatures of the fuel plate are sensitive to the variations of the heat transfer coefficients whose values are lower, but their effects are weakened and slight when the heat transfer coefficients increase and reach a certain extent. Increasing the heat generation rate leads to elevating the internal temperatures. The temperatures and the maximum temperature differences within the plate increase along with the particle volume fractions. The surface thermal flux goes up along with particle volume fractions and heat generation rates, but the effects of surface heat transfer coefficients are not evident.

  7. The fuel cell model of abiogenesis: a new approach to origin-of-life simulations.

    Science.gov (United States)

    Barge, Laura M; Kee, Terence P; Doloboff, Ivria J; Hampton, Joshua M P; Ismail, Mohammed; Pourkashanian, Mohamed; Zeytounian, John; Baum, Marc M; Moss, John A; Lin, Chung-Kuang; Kidd, Richard D; Kanik, Isik

    2014-03-01

    In this paper, we discuss how prebiotic geo-electrochemical systems can be modeled as a fuel cell and how laboratory simulations of the origin of life in general can benefit from this systems-led approach. As a specific example, the components of what we have termed the "prebiotic fuel cell" (PFC) that operates at a putative Hadean hydrothermal vent are detailed, and we used electrochemical analysis techniques and proton exchange membrane (PEM) fuel cell components to test the properties of this PFC and other geo-electrochemical systems, the results of which are reported here. The modular nature of fuel cells makes them ideal for creating geo-electrochemical reactors with which to simulate hydrothermal systems on wet rocky planets and characterize the energetic properties of the seafloor/hydrothermal interface. That electrochemical techniques should be applied to simulating the origin of life follows from the recognition of the fuel cell-like properties of prebiotic chemical systems and the earliest metabolisms. Conducting this type of laboratory simulation of the emergence of bioenergetics will not only be informative in the context of the origin of life on Earth but may help in understanding whether life might emerge in similar environments on other worlds.

  8. Determination of Experimental Fuel Rod Parameters using 3D Modelling of PCMI with MPS Defect

    Energy Technology Data Exchange (ETDEWEB)

    Casagranda, Albert [Idaho National Laboratory; Spencer, Benjamin Whiting [Idaho National Laboratory; Pastore, Giovanni [Idaho National Laboratory; Novascone, Stephen Rhead [Idaho National Laboratory; Hales, Jason Dean [Idaho National Laboratory; Williamson, Richard L [Idaho National Laboratory; Martineau, Richard Charles [Idaho National Laboratory

    2016-05-01

    An in-reactor experiment is being designed in order to validate the pellet-cladding mechanical interaction (PCMI) behavior of the BISON fuel performance code. The experimental parameters for the test rod being placed in the Halden Research Reactor are being determined using BISON simulations. The 3D model includes a missing pellet surface (MPS) defect to generate large local cladding deformations, which should be measureable after typical burnup times. The BISON fuel performance code is being developed at Idaho National Laboratory (INL) and is built on the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework. BISON supports both 2D and 3D finite elements and solves the fully coupled equations for solid mechanics, heat conduction and species diffusion. A number of fuel performance effects are included using models for swelling, densification, creep, relocation and fission gas production & release. In addition, the mechanical and thermal contact between the fuel and cladding is explicitly modelled using a master-slave based contact algorithm. In order to accurately predict PCMI effects, the BISON code includes the relevant physics involved and provides a scalable and robust solution procedure. The depth of the proposed MPS defect is being varied in the BISON model to establish an optimum value for the experiment. The experiment will be interrupted approximately every 6 months to measure cladding radial deformation and provide data to validate BISON. The complete rodlet (~20 discrete pellets) is being simulated using a 180° half symmetry 3D model with MPS defects at two axial locations. In addition, annular pellets will be used at the top and bottom of the pellet stack to allow thermocouples within the rod to measure the fuel centerline temperature. Simulation results will be presented to illustrate the expected PCMI behavior and support the chosen experimental design parameters.

  9. Analysis of Experimental Fuel Rod Parameters using 3D Modelling of PCMI with MPS Defect

    Energy Technology Data Exchange (ETDEWEB)

    Casagranda, Albert [Idaho National Laboratory; Spencer, Benjamin Whiting [Idaho National Laboratory; Pastore, Giovanni [Idaho National Laboratory; Novascone, Stephen Rhead [Idaho National Laboratory; Hales, Jason Dean [Idaho National Laboratory; Williamson, Richard L [Idaho National Laboratory; Martineau, Richard Charles [Idaho National Laboratory

    2016-06-01

    An in-reactor experiment is being designed in order to validate the pellet-cladding mechanical interaction (PCMI) behavior of the BISON fuel performance code. The experimental parameters for the test rod being placed in the Halden Research Reactor are being determined using BISON simulations. The 3D model includes a missing pellet surface (MPS) defect to generate large local cladding deformations, which should be measureable after typical burnup times. The BISON fuel performance code is being developed at Idaho National Laboratory (INL) and is built on the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework. BISON supports both 2D and 3D finite elements and solves the fully coupled equations for solid mechanics, heat conduction and species diffusion. A number of fuel performance effects are included using models for swelling, densification, creep, relocation and fission gas production & release. In addition, the mechanical and thermal contact between the fuel and cladding is explicitly modelled using a master-slave based contact algorithm. In order to accurately predict PCMI effects, the BISON code includes the relevant physics involved and provides a scalable and robust solution procedure. The depth of the proposed MPS defect is being varied in the BISON model to establish an optimum value for the experiment. The experiment will be interrupted approximately every 6 months to measure cladding radial deformation and provide data to validate BISON. The complete rodlet (~20 discrete pellets) is being simulated using a 180° half symmetry 3D model with MPS defects at two axial locations. In addition, annular pellets will be used at the top and bottom of the pellet stack to allow thermocouples within the rod to measure the fuel centerline temperature. Simulation results will be presented to illustrate the expected PCMI behavior and support the chosen experimental design parameters.

  10. Dynamic modelling and stability parametric analysis of a flexible spacecraft with fuel slosh

    Science.gov (United States)

    Gasbarri, Paolo; Sabatini, Marco; Pisculli, Andrea

    2016-10-01

    Modern spacecraft often contain large quantities of liquid fuel to execute station keeping and attitude manoeuvres for space missions. In general the combined liquid-structure system is very difficult to model, and the analyses are based on some assumed simplifications. A realistic representation of the liquid dynamics inside closed containers can be approximated by an equivalent mechanical system. This technique can be considered a very useful mathematical tool for solving the complete dynamics problem of a space-system containing liquid. Thus they are particularly useful when designing a control system or to study the stability margins of the coupled dynamics. The commonly used equivalent mechanical models are the mass-spring models and the pendulum models. As far as the spacecraft modelling is concerned they are usually considered rigid; i.e. no flexible appendages such as solar arrays or antennas are considered when dealing with the interaction of the attitude dynamics with the fuel slosh. In the present work the interactions among the fuel slosh, the attitude dynamics and the flexible appendages of a spacecraft are first studied via a classical multi-body approach. In particular the equations of attitude and orbit motion are first derived for the partially liquid-filled flexible spacecraft undergoing fuel slosh; then several parametric analyses will be performed to study the stability conditions of the system during some assigned manoeuvers. The present study is propaedeutic for the synthesis of advanced attitude and/or station keeping control techniques able to minimize and/or reduce an undesired excitation of the satellite flexible appendages and of the fuel sloshing mass.

  11. Development of a System Dynamics Model for Evaluating the Economics of an Advanced CANDU Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Jong Yeob; Park, Joo Hwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-10-15

    failure risk of commercializing CANFLEX-NU fuel. The power de-rating of Wolsong Unit 2, 3 and 4 will be expected from 2012, 2013 and 2014, respectively, and the compensation effect of the de-rated power by using CANFLEX-NU fuel is increased as the time goes. Therefore, the starting point of license study affects to the economic profits because it requires usually more than 4 years. A system dynamics model (SD model) was developed to carry out the economic evaluation by using the commercial SD code Vensim DSS Professional. From the economic evaluation results, it was found that the early starting of a licensing study from 2009 results in better economic profits than the late starting of a licensing study from 2012 if the probability of a successful implementation is higher than 20%.

  12. Determination of optimal reformer temperature in a reformed methanol fuel cell system using ANFIS models and numerical optimization methods

    DEFF Research Database (Denmark)

    Justesen, Kristian Kjær; Andreasen, Søren Juhl

    2015-01-01

    In this work a method for choosing the optimal reformer temperature for a reformed methanol fuel cell system is presented based on a case study of a H3 350 module produced by Serenergy A/S. The method is based on ANFIS models of the dependence of the reformer output gas composition on the reformer...... temperature and fuel flow, and the dependence of the fuel cell voltage on the fuel cell temperature, current and anode supply gas CO content. These models are combined to give a matrix of system efficiencies at different fuel cell currents and reformer temperatures. This matrix is then used to find...... the reformer temperature which gives the highest efficiency for each fuel cell current. The average of this optimal efficiency curve is 32.11% and the average efficiency achieved using the standard constant temperature is 30.64% an increase of 1.47 percentage points. The gain in efficiency is 4 percentage...

  13. Use of multiscale zirconium alloy deformation models in nuclear fuel behavior analysis

    Science.gov (United States)

    Montgomery, Robert; Tomé, Carlos; Liu, Wenfeng; Alankar, Alankar; Subramanian, Gopinath; Stanek, Christopher

    2017-01-01

    Accurate prediction of cladding mechanical behavior is a key aspect of modeling nuclear fuel behavior, especially for conditions of pellet-cladding interaction (PCI), reactivity-initiated accidents (RIA), and loss of coolant accidents (LOCA). Current approaches to fuel performance modeling rely on empirical constitutive models for cladding creep, growth and plastic deformation, which are limited to the materials and conditions for which the models were developed. To improve upon this approach, a microstructurally-based zirconium alloy mechanical deformation analysis capability is being developed within the United States Department of Energy Consortium for Advanced Simulation of Light Water Reactors (CASL). Specifically, the viscoplastic self-consistent (VPSC) polycrystal plasticity modeling approach, developed by Lebensohn and Tomé [1], has been coupled with the BISON engineering scale fuel performance code to represent the mechanistic material processes controlling the deformation behavior of light water reactor (LWR) cladding. A critical component of VPSC is the representation of the crystallographic nature (defect and dislocation movement) and orientation of the grains within the matrix material and the ability to account for the role of texture on deformation. A future goal is for VPSC to obtain information on reaction rate kinetics from atomistic calculations to inform the defect and dislocation behavior models described in VPSC. The multiscale modeling of cladding deformation mechanisms allowed by VPSC far exceed the functionality of typical semi-empirical constitutive models employed in nuclear fuel behavior codes to model irradiation growth and creep, thermal creep, or plasticity. This paper describes the implementation of an interface between VPSC and BISON and provides initial results utilizing the coupled functionality.

  14. Dynamic modeling, experimental evaluation, optimal design and control of integrated fuel cell system and hybrid energy systems for building demands

    Science.gov (United States)

    Nguyen, Gia Luong Huu

    Fuel cells can produce electricity with high efficiency, low pollutants, and low noise. With the advent of fuel cell technologies, fuel cell systems have since been demonstrated as reliable power generators with power outputs from a few watts to a few megawatts. With proper equipment, fuel cell systems can produce heating and cooling, thus increased its overall efficiency. To increase the acceptance from electrical utilities and building owners, fuel cell systems must operate more dynamically and integrate well with renewable energy resources. This research studies the dynamic performance of fuel cells and the integration of fuel cells with other equipment in three levels: (i) the fuel cell stack operating on hydrogen and reformate gases, (ii) the fuel cell system consisting of a fuel reformer, a fuel cell stack, and a heat recovery unit, and (iii) the hybrid energy system consisting of photovoltaic panels, fuel cell system, and energy storage. In the first part, this research studied the steady-state and dynamic performance of a high temperature PEM fuel cell stack. Collaborators at Aalborg University (Aalborg, Denmark) conducted experiments on a high temperature PEM fuel cell short stack at steady-state and transients. Along with the experimental activities, this research developed a first-principles dynamic model of a fuel cell stack. The dynamic model developed in this research was compared to the experimental results when operating on different reformate concentrations. Finally, the dynamic performance of the fuel cell stack for a rapid increase and rapid decrease in power was evaluated. The dynamic model well predicted the performance of the well-performing cells in the experimental fuel cell stack. The second part of the research studied the dynamic response of a high temperature PEM fuel cell system consisting of a fuel reformer, a fuel cell stack, and a heat recovery unit with high thermal integration. After verifying the model performance with the

  15. Source‐receiver two‐way wave extrapolation for prestack exploding‐reflector modeling and migration

    KAUST Repository

    Alkhalifah, Tariq Ali

    2010-10-17

    While most of the modern seismic imaging methods perform imaging by separating input data into parts (shot gathers), we develop a formulation that is able to incorporate all available data at once while numerically propagating the recorded multidimensional wavefield backward in time. While computationally extensive, this approach has the potential of generating accurate images, free of artifacts associated with conventional approaches. We derive novel high‐order partial differential equations in source‐receiver‐time domain. The fourth order nature of the extrapolation in time has four solutions two of which correspond to the ingoing and outgoing P‐waves and reduces to the zero‐offset exploding‐reflector solutions when the source coincides with the receiver. Using asymptotic approximations, we develop an approach to extrapolating the full prestack wavefield forward or backward in time.

  16. A model for evolution of oxygen potential and stoichiometry deviation in irradiated UO 2 fuel

    Science.gov (United States)

    Ozrin, V. D.

    2011-12-01

    A model for radial redistribution of oxygen in irradiated UO 2 fuel under conditions of temperature and fission rate gradients has been developed. The oxygen transport in irradiated fuel is considered as a two-scale problem. On the local scale defined by the grain size, irradiated fuel is considered as a multi-phase system including solid solution of fission products in UO 2 matrix, solid precipitates (metal phase, grey phase of complex ternary compounds, the phase of condensed CsI) formed at the gas/solid interface and the gas phase in the intergranular bubbles. Intraganular transport of fission products is described by a set of diffusion equations which are supplemented by the condition of partial thermochemical equilibrium in the subsystem "precipitates & gas phase". The boundary conditions are formulated basing on thermochemical equilibrium on the interface of subsystems "solid solution" and "precipitates & gas phase". Calculation of the partial thermochemical equilibrium yields local values of the oxygen chemical potential and the deviation from fuel stoichiometry. On the global scale defined by the fuel pellet size, spatial variations of the oxygen potential caused by the temperature gradients or the presence of sources/sinks at the pellet boundary determine thermal diffusion fluxes resulting in redistribution of oxygen. The whole set of equations describing local equilibration and the transport in the local and global scales is solved in a self-consistent manner. The model results for radial distribution of oxygen potential of UO 2 calculated for typical reactor operating conditions and the fuel burnup up ˜100 MW d/kg HM are in satisfactory agreement with experimental data.

  17. Inclusion of models to describe severe accident conditions in the fuel simulation code DIONISIO

    Energy Technology Data Exchange (ETDEWEB)

    Lemes, Martín; Soba, Alejandro [Sección Códigos y Modelos, Gerencia Ciclo del Combustible Nuclear, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Provincia de Buenos Aires (Argentina); Daverio, Hernando [Gerencia Reactores y Centrales Nucleares, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Provincia de Buenos Aires (Argentina); Denis, Alicia [Sección Códigos y Modelos, Gerencia Ciclo del Combustible Nuclear, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Provincia de Buenos Aires (Argentina)

    2017-04-15

    The simulation of fuel rod behavior is a complex task that demands not only accurate models to describe the numerous phenomena occurring in the pellet, cladding and internal rod atmosphere but also an adequate interconnection between them. In the last years several models have been incorporated to the DIONISIO code with the purpose of increasing its precision and reliability. After the regrettable events at Fukushima, the need for codes capable of simulating nuclear fuels under accident conditions has come forth. Heat removal occurs in a quite different way than during normal operation and this fact determines a completely new set of conditions for the fuel materials. A detailed description of the different regimes the coolant may exhibit in such a wide variety of scenarios requires a thermal-hydraulic formulation not suitable to be included in a fuel performance code. Moreover, there exist a number of reliable and famous codes that perform this task. Nevertheless, and keeping in mind the purpose of building a code focused on the fuel behavior, a subroutine was developed for the DIONISIO code that performs a simplified analysis of the coolant in a PWR, restricted to the more representative situations and provides to the fuel simulation the boundary conditions necessary to reproduce accidental situations. In the present work this subroutine is described and the results of different comparisons with experimental data and with thermal-hydraulic codes are offered. It is verified that, in spite of its comparative simplicity, the predictions of this module of DIONISIO do not differ significantly from those of the specific, complex codes.

  18. Mathematical modeling of channel-porous layer interfaces in PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Ehrhardt, M.; Fuhrmann, J.; Holzbecher, E.; Linke, A.

    2008-07-01

    In proton exchange membrane (PEM) fuel cells, the transport of the fuel to the active zones, and the removal of the reaction products are realized using a combination of channels and porous diffusion layers. In order to improve existing mathematical and numerical models of PEM fuel cells, a deeper understanding of the coupling of the flow processes in the channels and diffusion layers is necessary. After discussing different mathematical models for PEM fuel cells, the work focuses on the description of the coupling of the free flow in the channel region with the filtration velocity in the porous diffusion layer as well as interface conditions between them. The difficulty in finding effective coupling conditions at the interface between the channel flow and the membrane lies in the fact that often the orders of the corresponding differential operators are different, e.g., when using stationary (Navier-)Stokes and Darcy's equation. Alternatively, using the Brinkman model for the porous media this difficulty does not occur. We review different interface conditions, including the well-known Beavers-Joseph-Saffman boundary condition and its recent improvement by Le Bars and Worster. (orig.)

  19. Predictive model of transport properties of fuel cell membrane : from microscopic to macroscopic level

    Energy Technology Data Exchange (ETDEWEB)

    Colinart, T.; Lottin, O.; Maranzana, G.; Didierjean, S.; Moyne, C. [Nancy-Univ., Vandoeuvre-les-Nancy (France). Laboratoire d' Energetique et de Mecanique Theorique et Appliquee

    2007-07-01

    Because of their attractiveness as efficient and clean energy producers, proton exchange membrane fuel cells (PEMFC) can be used in automotive and small stationary applications. The electrochemical reaction takes place on two electrodes separated by a ionomer membrane. An important component of fuel cell water management and a problem for fuel cell performances involves the transport of protons from the anode to the cathode as its' transport properties are highly water dependent. Nafion membranes are widely used as an electrolyte for PEMFC. This paper presented a model to predict transport properties of polymer membranes such as Nafion used as electrolytes in a low temperature fuel cell. The paper discussed the electrical double layer that was used to determine surface charge density. The paper then discussed the analytical solution to the physical problem in the diffuse part of a cylindrical pore which involved solving the Poisson-Boltzmann, the Navier-Stokes and the Nernst-Planck equations. The properties of the electrolytic solution were equal to those of water and they were considered to be constant within the pore. A literature comparison with other models was also pre