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Srinivasan V.,Advanced Simulation Technologies
ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011 | Year: 2011

In this paper, the development of a new mass transfer model to simulate the thermal and phase change characteristics encountered by binary mixtures during flow boiling process is discussed. A new boiling mass transfer model based on detailed bubble dynamic effects, inclusive of local bubble shear, drag and buoyancy dynamics, has been developed and full implemented within the commercial CFD code AVL FIRE v2010. In the present study the phasic mass, momentum and energy equations are solved in a segregated fashion in conjunction with an interfacial area transport and a number density equation to study the heat and mass transfer characteristics of binary flow boiling inside a rectangular duct. Turbulence in the fluidic system and those generated by the bubbly flow are treated using an advanced k-ζ-f model. The simulation results comprising of flow variables such as volume fraction, fluidic velocities and temperature and the resultant heat flux generated on the heated wall section clearly monitors the suppression in heat transfer coefficients with enhancement in flow convection. Competing mechanisms such as phase change process and turbulent convection are identified to influence the heat transfer characteristics. In particular, the varying influence of the mass transfer effects on the heat flux characteristics with alteration in wall temperature is well demonstrated. Comparisons of the predicted heat transfer coefficients for varying wall superheat and varying fluidic velocity indicates a very good agreement with experimental data, wherever available. Description of the flow field inclusive of interfacial area and number density distribution is provided. The current model can be easily extended to simulate multiphase flow in complex systems such as a cooling water jacket for automotive applications. Copyright © 2011 by ASME. Source


Srinivasan V.,Advanced Simulation Technologies
ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011 | Year: 2011

In this article, a fixed-grid finite volume approach to simulate the convection-dominated solidification/melting process is presented. An Eulerian multi - fluid modeling approach is employed to track the phase change interface by obtaining solutions to governing volume fraction, momentum and energy transport equations. The liquid-solid interfacial phase transfer effects are modeled using a novel mass transfer function incorporating the latent heat modification due to the phase change process. The alterations in the local phasic fractions and the resultant cellular latent heat is correctly realized using a source term approach within a homogeneous enthalpy modeling framework. The model fully implemented within the commercial CFD code AVL FIRE® V2010 is tested and validated using a (1) classical 1D Stefan's problem (2) melting of gallium (3) tin solidification scenario. In addition to the mass, momentum and energy solutions, transport of species within multi-component liquids is made possible, thereby allowing means for efficient and accurate coupling between the temperature and concentration fields within the system. Description of the phase change fronts, the local velocity and temperature fields are discussed in detail. Results from the simulations are compared against experimental data wherever available. Discussions pertaining to the applicability of the model and its robustness are elaborated within the article. Copyright © 2011 by ASME. Source


Grant
Agency: Cordis | Branch: FP7 | Program: BSG-SME | Phase: SME-2012-1 | Award Amount: 1.30M | Year: 2013

Modular construction is used in housing and residential buildings because it is fast to construct and of high quality. This proposal provides the research necessary to extend two types of modular building systems into high-rise building applications where means of providing stability and in some areas, seismic resistance are very important. In addition, the proposal will lead to quantification of the sustainability benefits and acoustic performance, that affect the use of modular construction in the residential building sector. With this information, it is possible to develop design guidance to support the use of these modular systems and to create new markets in high-rise and mixed use buildings. The research will involve full-scale physical tests on modules and on groups of modules, and supprted by finite element analyses as well as on -site measurements of performance. The tests will cover the basic structural performance of the modules and their connections and in particular, their robustness to removal of supports. This will aslso simulate the loss of support and tying action in seismic events. The structural guidance will be presented in the form of application rules to Eurocode 3. Case studies and architectural information will be presented to support the use of the modular systems in practice. This will extend to building typologies using the developed modular systems. seminars and other dissemination activities will be carried out to exploit the results of this research and to create market awareness.


Grant
Agency: Cordis | Branch: FP7 | Program: CP-IP | Phase: EeB.NMP.2011-3 | Award Amount: 9.94M | Year: 2012

The building envelope (roof, faade and basements) is the key element to address in order to achieve the energy efficiency in the retrofitting of buildings, where the faade represent the largest part of the heat transmission surface and includes a number of critical components (like windows, balconies, ventilation units,etc) and thermal bridge phenomena. The present project aims to develop an energy efficient integrated system composed by an innovative concept, built on composite materials, and advanced multifunctional panels with technological modules integrated in the faade for building envelope retrofitting. The following solutions will be developed: - Innovative faade concept for retrofitting based on new industrialized constructive system integrating advanced multifunctional panels, technological modules and installations; allowing personalized configurations for each faade typology, orientation and local climate conditions, always using standardized panels and technological modules. It will be cost effective in service life, with low maintenance, easy assembly and disassembly. - Energy Efficient panels and modules integrated in the faade will include a particular technology for reducing energy demand of the building or for supplying energy by means of RES; two new energy efficient modules will be developed: Advanced Passive Solar Protector and Energy Absorption auto mobile unit, Advanced Passive Solar Collector and Ventilation Module. - A set of flexible, lightweight and cost-effective structural panels, easy to be industrialized and assembled, made of composite materials (FRP - Fibre Reinforced Polymer). The solution will be demonstrated in a real building in Spain, in a region with a continental climate, where extreme conditions in summer up to (>35C) and in winter (<0C), covering the different seasons. The building will be monitored before and after the retrofitting with the new Retrofitting system to evaluate the performance solutions.


Srinivasan V.,Advanced Simulation Technologies | Greif D.,A-D Technologies | Basara B.,AVL List GmbH
Quenching Control and Distortion - Proceedings of the 6th International Quenching and Control of Distortion Conference, Including the 4th International Distortion Engineering Conference | Year: 2012

In this article, discussions pertaining to a robust computational methodology to simulate the immersion quenching heat treatment process are presented. Computational Fluid Dynamics (CFD) study carried out using the commercial CFD code AVL FIRE® v2011, performs coupled computations encompassing both the fluid domain, containing the quench bath, and the immersing solid structure(s) through a novel interface coupling procedure, which allows data exchange such as of phase change rates, convection coefficients, heat fluxes etc across the domain boundaries. In the fluid domain, the boiling multiphase flow, triggered by the dipping hot solid part into a sub-cooled liquid bath, is handled using an Eulerian multi-fluid method. The ensuing heat and mass transfer effects are modeled based on the different boiling modes, film or nucleate boiling regime, prevalent in the system. In the solid domain, solutions to the energy equation provide the necessary temperature evolution dynamics. Separate computational domains constructed for the quenched solid part(s) and the fluid (quenchant) flow are numerically coupled at the interface of the solid-fluid boundaries leading to a tightly coupled multi-domain system. The discussed quenching procedure is applied to a wide variety of quenching scenarios involving immersion cooling of trapezoidal blocks, engine cylinder heads and other complex structures. Results in the form of temperature evolution in the solids, volume fraction distribution in the fluid domain are compared with the experimental recordings, wherever available. Elaborate descriptions of the numerical and physical models employed in the procedure are provided. Extended applications of the current modeling procedure are also noted. Copyright © 2012 ASM International® All rights reserved. Source

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