G. Selembo, P. Selembo, J. Stanton, and G. Paulsen
University of North Carolina
Surface aeration systems are used in the wastewater treatment industry for the transfer of oxygen in the activated sludge process. These systems are capital intensive and also require a significant amount of energy to operate. Scale-up and design of these systems is largely empirical, and due to the size of these systems, modifications for experimental testing can be economically prohibitive. ...
Analysis of Superheater Tubes with Mutual Irradiation as Applied to a Solar Receiver Steam Generator
N. Lemcoff, S. Wyatt
Rensselaer Polytechnic Institute, Hartford, CT, USA
Alstom Power, Windsor, CT, USA
The objective of this paper is to analyze the temperature variations within a superheater tube of a solar receiver steam generator. The tube is heated by concentrated, collimated solar irradiation with major cooling by an internal steam flow. The influence of heat loss by radiation, internal convection, and conduction are considered. Analytical models are obtained for an isolated tube, and the ...
C. Wylock, S. Goffin, M. Aubinet, B. Longdoz, B. Haut
Université Libre de Bruxelles (ULB), Transfers, Interfaces and Processes (TIPs), Brussels, Belgium
University of Liège-Gembloux Agro-Bio Tech, Unit of Biosystem Physics, Gembloux, Belgium
INRA, Centre INRA de Nancy, UMR1137 Ecologie et Ecophysiologie Forestières, Champenoux, France
The assessment of forest soil respiration and its isotopic composition is one of the important issues for the carbon cycling modeling (greenhouse gas emission control) because it is often inaccurate. Soil respiration is a complex process, depending on the coupling of several phenomena, which is therefore highly sensitive to any disturbance. In this work, the dynamics of the transport of two ...
R.R. Thorat, H. Bruining
Petroleum Engineering, CiTG, TU Delft, Delft, The Netherlands
Recovery of oil by gas injection is usually inefficient due to the low viscosity of the gas, which results in bypassing of the oil. By adding surfactant solutions it is possible to get in-situ foam formation. Foam has a much higher “viscosity” and hence does not bypass the oil, leading to enhanced oil recovery. In this context, the foam propagation is studied experimentally and theoretically. ...
V. Nicolas, C. Doursat, D. Grenier, T. Lucas, D. Flick
Institut de recherche en sciences et technologies pour l'environnement et l'agriculture, Rennes, France
AgroParisTech, UMR1145 Ingénierie Procédés Aliments, Massy, France
Bread is a food product which various complex physico-chemical phenomena occur during the cooking process. Thus, phenomena of heat and mass transfer are coupled to the deformation. In addition, bread is a multiphase product (solid, liquid and vapor) and composed of various components (dry matter, water, air and carbon dioxide). A 2D model is developed with COMSOL Multiphysics® 4.3b witch ...
G. Debenest, and M. Quintard
Institut de Mécanique des Fluides de Toulouse
Flows in highly heterogeneous media are found in many practical fields, such as hydrology, petroleum engineering, and chemical engineering. The case of two-region heterogeneous media (fractured media, catalytic beds, etc.) plays a fundamental role. The different questions associated to this specific case are illustrated in this paper for two different kinds of transport: (i) flow of a slightly ...
Influence of COMSOL on the Design and Testing of the High Flux Isotope Reactor HB-4 Cold Source: Validation of the Simulation
J. D. Freels
Oak Ridge National Laboratory
This presentation concerns our numerical and experimental research on the High Flux Isotope Reactor HFIR, located at the Oak Ridge National Laboratory. In this presentation we give a Brief Pictorial Introduction to the HFIR, som physical properties of Supercritical Hydrogen, and Simulations of both natural and forced convection problems using COMSOL Multiphysics. This presentation also ...
COMSOL Multiphysics for Efficient Solution of a Transient Reaction-Diffusion System with Fast Reaction
M.K. Gobbert, A. Churchill, G. Wang, and T.I. Seidman
Department of Mathematics and Statistics, University of Maryland, Baltimore County, Baltimore, Maryland, USA
A reaction between chemical species is modeled by a particular reaction pathway, in which one reaction is very fast relative to the other one. The diffusion controlled reactions of these species together with a reaction intermediate are described by a system of three transient reaction diffusion equations over a two-dimensional spatial domain. In the asymptotic limit of the reaction parameter ...
Modeling of Coupled Fluid Flow and Shear-induced Solidification Kinetics in Rheocasting of Aluminium Alloys
G. Maizza, and G. Lorenzatto
Politecnico di Torino
Dipartimento di Scienza dei Materiali ed Ingegneria Chimica
The model proposed by Schneider et al., for polymers is herein adapted in order to assess its suitability in elucidating the thixotropic behavior of aluminum alloys. The COMSOL Multiphysics program is employed to solve the inherent coupled mathematical problem, consisting in the kinetic ordinary differential equations and the momentum and energy transport partial differential equations. The ...
A. Melas, A.G. Konstandopoulos, L. Isella, Y. Drossinos
Department of Chemical Engineering, Aristotle University, Thessaloniki, Greece
European Commission, DG Energy, Luxemburg
European Commission, Joint Research Centre, Ispra, Italy
Aerosol and colloid aggregates are complex fractal-like structures composed of primary spheres. The drag force exerted on a fractal-like object is usually determined by solving numerically the Stokes equation. In this study we calculate it by relating it to a molecule-aggregate collision rate. We create the fractal aggregates with a cluster-cluster aggregation algorithm using the software ...