Interfaces in Higher Order Phase Change Models

1984 ◽  
Vol 111 (1-2) ◽  
pp. 45-56
Author(s):  
P. Delano Hagan-Von Dreele ◽  
P. H. Von Dreele
Keyword(s):  
Phase Change ◽  
Higher Order ◽  
Change Models

Coupled Electro-Thermal-Phase Change Modeling of a Chalcogenide Switch

2006 ◽  
Author(s):  
Navdeep Singh Dhillon ◽  
Jayathi Y. Murthy
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Charge Transport ◽  
Crystallization Kinetics ◽  
Change Models ◽  
Switching Model ◽  
Memory Switching ◽  
Continuity Equations ◽  
Thermal Phase ◽  
Fully Coupled

A coupled electro-thermal-phase change numerical model is developed to model the threshold and memory switching processes in a chalcogenide switch based on phase change memory (PCM) technology. Coupled electrical and thermal transport coupled to phase change and crystallization kinetics are solved. Charge transport has been implemented using simplified carrier continuity equations with a threshold switching model for electrical conductivity. Heat transfer is modeled using a Fourier model, accounting for latent heat through a fixed-grid enthalpy formulation. Phase change is modeled using the Johnson-Mehl equations for crystallization kinetics. Thermal conductivity and electrical resistivity changes due to phase change are modeled using a local percolation model. The charge transport and circuit equations are fully coupled with the heat transfer and phase change models to accurately simulate the switching process. SET and RESET pulses are simulated to demonstrate that the model is able to capture the underlying physics well.

Numerical Simulation of Immersion Quench Cooling Process: Part I

2008 ◽  
Author(s):  
Vedanth Srinivasan ◽  
Kil-min Moon ◽  
David Greif ◽  
DeMing Wang ◽  
Myung-hwan Kim
Keyword(s):  
Phase Change ◽  
Nucleate Boiling ◽  
Vapor Flow ◽  
Cooling Process ◽  
Change Models ◽  
Liquid Domain ◽  
Commercial Code ◽  
Quenching Process ◽  
Solid Part ◽  
Quench Cooling

In this article, we describe a newly developed modeling procedure to simulate the immersion quench cooling process using the commercial code AVL-FIRE. The boiling phase change process, triggered by the dipping hot solid part into a subcooled liquid bath and the ensuing two-phase flow is handled using an Eulerian two-fluid method. Mass transfer effects are modeled based on different boiling modes such as film or nucleate boiling regime prevalent in the system. Separate computational domains constructed for the quenched solid part and the liquid (quenchant) domain are numerically coupled at the interface of the solid-liquid boundaries using the AVL-Code-Coupling-Interface (ACCI) feature. The advanced ACCI procedure allows the information pertaining to the phase change rates in the liquid domain to appear as cooling rates on the quenched solid boundaries. As a consequence, the code handles the multiphase flow dynamics in the liquid domain in conjunction with the temperature evolution in the solid region in a tightly coupled fashion. The methodology, implemented in the commercial code AVL-FIRE, is exercised in simulating the quenching of solid parts. In part I of the present research, phase change models are validated by simulating a work piece quenching process for which measurement data are available for various water temperature ranging from 20C to 80C. The computations provide a detailed description of the vapor and temperature fields in the liquid and solid domain at various time instants. In particular, the modifications arising in the liquid-vapor flow field in the near vicinity of the solid interface as a function of the boiling mode is well accommodated. The temperature history predicted by our model at different monitoring points, under different subcooling conditions, correlate very well with the experimental data wherever available. In part II, the model is further applied to real engine cylinder head quenching process and assessment is made for the cooling curves for various measuring points. Overall, the predictive capability of the new quenching model is well demonstrated.

scholarly journals Nonlinear evolution inclusions arising from phase change models

2007 ◽  
Vol 57 (4) ◽  
pp. 1067-1098 ◽  
Author(s):  
Pierluigi Colli ◽  
Pavel Krejčí ◽  
Elisabetta Rocca ◽  
Jürgen Sprekels
Keyword(s):  
Phase Change ◽  
Nonlinear Evolution ◽  
Evolution Inclusions ◽  
Change Models

Simple Mechanistically Consistent Formulation for Volume-of-Fluid Based Computations of Condensing Flows

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Alexander S. Rattner ◽  
Srinivas Garimella
Keyword(s):  
Phase Change ◽  
Computational Cost ◽  
Volume Of Fluid ◽  
Film Condensation ◽  
Change Models ◽  
Software Complexity ◽  
Interface Reconstruction ◽  
Mesh Resolution ◽  
Condensing Flows ◽  
Gas Volume

Numerous investigations have been conducted to extend adiabatic liquid–gas volume-of-fluid (VOF) flow solvers to include condensation phenomena by adding an energy equation and phase-change source terms. Some proposed phase-change models employ empirical rate parameters, or adapt heat-transfer correlations, and thus must be tuned for specific applications. Generally applicable models have also been developed that rigorously resolve the phase-change process, but require interface reconstruction, significantly increasing computational cost, and software complexity. In the present work, a simplified first-principles-based condensation model is developed, which forces interface-containing mesh cells to the equilibrium state. The operation on cells instead of complex interface surfaces enables the use of fast graph algorithms without reconstruction. The model is validated for horizontal film condensation, and converges to exact solutions with increasing mesh resolution. Agreement with established results is demonstrated for smooth and wavy falling-film condensation.

Simple Mechanistically Consistent Formulation for Volume-of-Fluid Based Computations of Condensing Flows

2013 ◽  
Author(s):  
Alexander S. Rattner ◽  
Srinivas Garimella
Keyword(s):  
Phase Change ◽  
Computational Cost ◽  
Film Condensation ◽  
Falling Film ◽  
Change Models ◽  
Software Complexity ◽  
Interface Reconstruction ◽  
Mesh Resolution ◽  
Condensing Flows ◽  
Consistent Formulation

Numerous investigations have been conducted to extend adiabatic liquid-gas VOF flow solvers to include condensation phenomena by adding an energy equation and phase-change source terms. Some proposed phase-change models employ empirical rate parameters, or adapt heat transfer correlations, and thus must be tuned for specific applications. Generally applicable models have also been developed that rigorously resolve the phase-change process, but require interface reconstruction, significantly increasing computational cost and software complexity. In the present work, a simplified first-principles-based condensation model is developed, which forces interface-containing mesh cells to the equilibrium state. The operation on cells instead of complex interface surfaces enables the use of fast graph algorithms without reconstruction. The model is validated for horizontal film condensation, and converges to exact solutions with increasing mesh resolution. Agreement with established results is demonstrated for smooth and wavy falling-film condensation.

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