Papers by Robert Brewster
Tlm-rnal-hydraulic analyses play an important role in design and reload analysis of nuclear power... more Tlm-rnal-hydraulic analyses play an important role in design and reload analysis of nuclear power plants. These analyses have historical y relied on early generation computational fluid dynamics capabilities, originally developed in the 1960s and 1970s. Over the last twenty years, however, dramatic improvements in both computational fluid dynamics codes in the commercial sector and in computing power have taken place. These developments offer the possibility of performing large scale, high fidelity, core thermal hydraulics analysis. Such analyses will allow a determination of the conservatism employed in traditional design approaches and possibly justify the operation of nuclear power systems at higher powers without compromising safety margins. The objective of this work is to demonstrate such a large scale analysis approach using a state of the art CFD code, STAR-CD, and the computing power of massively parallel computers, provided by IBM.
Tlm-rnal-hydraulic analyses play an important role in design and reload analysis of nuclear power... more Tlm-rnal-hydraulic analyses play an important role in design and reload analysis of nuclear power plants. These analyses have historical y relied on early generation computational fluid dynamics capabilities, originally developed in the 1960s and 1970s. Over the last twenty years, however, dramatic improvements in both computational fluid dynamics codes in the commercial sector and in computing power have taken place. These developments offer the possibility of performing large scale, high fidelity, core thermal hydraulics analysis. Such analyses will allow a determination of the conservatism employed in traditional design approaches and possibly justify the operation of nuclear power systems at higher powers without compromising safety margins. The objective of this work is to demonstrate such a large scale analysis approach using a state of the art CFD code, STAR-CD, and the computing power of massively parallel computers, provided by IBM.
Microelectronics Reliability, 1993
In this paper, we provide a thermal analysis for a component mounted on a carrier via solder inte... more In this paper, we provide a thermal analysis for a component mounted on a carrier via solder interconnections, with emphasis on understanding how the thermal gradients across the solder interconnections develop during the power-on transient. A 1-D model is sought for its simplicity, while the important features of the problem are kept intact. Closed-form solutions are obtained whel2n the thermal mass of the component is much less than the thermal mass of the carrier. The asymptotic solutions are compared with the numerical solutions of the same set of equations. Finite element solutions and experimental data are also obtained to assess the validity of the 1-D model as a predictor of the thermal gradients across the solder interconnections. Results of the analysis show that the thermal gradients across the solder interconnections reach a maximum at some early time before steady-state conditions are reached and that the thermally induced transient strains can be several times worse than the steady-state strains.
Journal of Fluids Engineering, 2013
This paper provides the results of numerical calculations of pressure drops and centerline veloci... more This paper provides the results of numerical calculations of pressure drops and centerline velocities for laminar fully-developed flows of non-Newtonian fluids in circular ducts. The particular non-Newtonian fluid model considered is the Cross model, which has shown the ability to model the behavior of time-independent purely-viscous fluids over a wide range of shear rates. It is shown that the Cross model is equivalent to the more recently proposed extended modified power law (EMPL) model, and an alternative formulation of the nondimensional parameters arising from the use of these models is explored. Results are presented for friction factors and nondimensional centerline velocities over a wide range of fluid and flow conditions, and it is shown that simpler constitutive models can be used in cases where the ratios of the limiting Newtonian viscosities are extreme. The implications of the results to the design and analysis of piping systems is considered, and simple and accurate c...
International Journal of Heat and Mass Transfer, 1994
Results of an experimental study of the convective heat and mass transfer processes for downward ... more Results of an experimental study of the convective heat and mass transfer processes for downward freezing from a horizontal surface into seawater at 35k, i.e. at oceanic salinity, are presented here. Liquid supercooling of about 50°C was detected at the cooling surface before freezing began. Supercooled water was also detected far from the cooling surface, under some conditions. This supercooling, before freezing, allowed the possibility for density extremum effects to arise under some conditions of low ambient water temperature and large extracted heat flux. After freezing, however, flow visualization revealed that the flow was downward, below the freezing surface. At the high cooling and freezing rate used in these experiments the ice layer and water-ice interface salinities were found to be only weakly dependent on the ice growth rate. Convective heat transfer rates were found to be strongly affected by solute rejection upon freezing.
W�rme- und Stoff�bertragung, 1987
ABSTRACT
Drying Technology, 2009
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Annals of the New York Academy of Sciences, 2006
International Journal of Heat and Mass Transfer, 1989
ABSTRACT
IEEE Transactions on Components, Hybrids, and Manufacturing Technology
As power dissipation at the chip level increases, current levels through power distribution wires... more As power dissipation at the chip level increases, current levels through power distribution wires increase correspondingly. This current Bow results in Joule heating in the package, which must be included in any sizing of the package cooling requirements. In this paper, we present an analysis of the temperature field resulting from the Joule heating in a metal wire surrounded by a nonheat generating (electrically insulating) material. Exact analytical solutions are given for when the heat generation rate is constant (independent of temperature) and linearly dependent on the temperature. Asymptotic solutions are given for arbitrarily temperature-dependent heat generation, when the insulating material thermal conductivity is much less than the thermal conductivity of the wire. A numerical example of practical interest is then considered. It is shown that neglecting the Joule heating in the wires can result in significant underprediction of the temperature. The effect of temperature on the electrical resistivity of the wire is shown to be negligible. The phenomenon of thermal runaway is also examined using stability theory and is shown to be unimportant in practical circumstances. NOMENCLATURE Voltage drop. Dimensionless substrate thickness. Current. Modified Bessel function of the first kind of order zero. Modified Bessel function of the first kind of order one. Substrate thermal conductivity. Via thermal conductivity. Dimensionless thermal conductivity ratio. Modified Bessel function of the second kind of order zero. Modified Bessel function of the second kind of order one. Via volumetric heat generation rate. Dimensionless via heat generation rate. Dimensionless coordinate. Coordinate. Electrical resistance. Dimensionless via radius. Substrate outer radius. Via radius (substrate inner radius). Dimensionless substrate temperature. Dimensionless via temperature. Substrate temperature. Via temperature.
Volume 6: Fluids and Thermal Systems; Advances for Process Industries, Parts A and B, 2011
ABSTRACT The Spallation Neutron Source (SNS) is an acceleratorbased neutron source at Oak Ridge N... more ABSTRACT The Spallation Neutron Source (SNS) is an acceleratorbased neutron source at Oak Ridge National Laboratory (ORNL). The nuclear spallation reaction occurs when a proton beam hits liquid mercury. This interaction causes thermal expansion of the liquid ...
Volume 3: Design and Analysis, 2012
Dry storage casks are used to store spent nuclear fuel after removal from the reactor spent fuel ... more Dry storage casks are used to store spent nuclear fuel after removal from the reactor spent fuel pool. Even prior to the Fukushima earthquake of March 2011, dry storage of spent fuel was receiving increased attention as many reactor spent fuel pools near their capacity. Many different types of cask designs are used, and one representative design is the TN-24P spent fuel cask, a non-ventilated steel cask with a shielded exterior shell and lid. The cask is typically filled with an inert gas such as helium, argon or nitrogen. In this paper, Computational Fluid Dynamics (CFD) calculation results for the thermal performance of the TN-24P cask using the commercial CFD software STAR-CCM+ are presented. Initial calculations employ a common approach of treating the fuel assemblies as conducting porous media with calibrated volume-averaged properties, and comparison to existing measured temperature data shows good agreement. One of the fuel assemblies is then replaced with a more accurate rep...
Journal of Fluid Mechanics, 1991
ABSTRACT
International Journal of Heat and Mass Transfer, 1988
ABSTRACT
Uploads
Papers by Robert Brewster