Heat transfer with kinetic phase transition in geomaterials

2021 ◽  
Vol 167 ◽  
pp. 120826
Author(s):  
Zhiqiang Liu ◽  
Danni Gong ◽  
Linlin Wang
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Kinetic Phase Transition

Fast forced liquid film spreading on a substrate: flow, heat transfer and phase transition

2010 ◽  
Vol 656 ◽  
pp. 189-204 ◽  
Author(s):  
ILIA V. ROISMAN
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Stokes Equations ◽  
Substrate Surface ◽  
Reynolds Numbers ◽  
Drop Impact ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Theoretical Predictions ◽  
Viscous Drop

This theoretical study is devoted to description of fluid flow and heat transfer in a spreading viscous drop with phase transition. A similarity solution for the combined full Navier–Stokes equations and energy equation for the expanding lamella generated by drop impact is obtained for a general case of oblique drop impact with high Weber and Reynolds numbers. The theory is applicable to the analysis of the phenomena of drop solidification, target melting and film boiling. The theoretical predictions for the contact temperature at the substrate surface agree well with the existing experimental data.

Numerical Modeling of Heat Transfer and Phase Transition in Programming the Ovonic Unified Memory Cells

2005 ◽  
Author(s):  
Evan Small ◽  
Sadegh M. Sadeghipour ◽  
Mehdi Asheghi
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Diffusion Equation ◽  
Dynamic Range ◽  
Semiconductor Device ◽  
Computer Code ◽  
Drift Diffusion ◽  
Thermally Induced ◽  
Design And Optimization ◽  
Phase Prediction

An Ovonic Unified Memory (OUM) cell is a semiconductor device that stores data by a thermally induced phase transition between polycrystalline (set) and amorphous (reset) states in a thin film of chalcogenide alloy. The small volume of active media acts as a programmable resistor switching between a high (amorphous) and low (crystalline) resistance state. The change in the film resistivity (>40X dynamic range) caused by this rapid, reversible structural change is measured to detect the state of the cell (set or reset) for read out. OUM can benefit from a simulator capable of predicting the electrical, thermal, and crystallization behavior for design and optimization, particularly at the present stage of the development. This paper reports on the efforts being made to prepare such a numerical simulator, using an existing finite element computer code as the source for thermal and electrical modeling, and a custom crystallization code for phase prediction. Heat generation in the device is by Joule heating and is achieved by passage of the electric current, which is obtained from the electrical simulation. This result appears in the heat source term of the heat transfer equation that is solved for thermal modeling. As the first attempt the Ohmic current-voltage relation was implemented successfully to simulate set and reset in a two dimensional model of OUM. Solution of the drift-diffusion equation is now underway to capture the semiconductor behavior of the I-V curve. A good progress is made however, still more works needs to be done to fully implement the drift diffusion equation.

Numerical Simulation of Melting of Phase Change Material in a Square Cavity with a Heat Source

2016 ◽  
Vol 685 ◽  
pp. 104-108 ◽  
Author(s):  
Nadezhda S. Bondareva ◽  
Mikhail A. Sheremet
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Heat Source ◽  
Local Heat ◽  
Effect Of Temperature ◽  
Square Cavity ◽  
Flow And Heat Transfer ◽  
The Finite Difference Method ◽  
Change Material ◽  
Melting And Solidification

Melting and solidification problems are important in applications of many industries. In the present work mathematical simulation of natural convection with phase transition inside an enclosure with a local heat source has been carried out. Partial differential equations with corresponding initial and boundary conditions have been solved using the finite difference method. The effect of temperature differences on fluid flow and heat transfer has been discussed.

scholarly journals Experimental Research on the Thermal Performance of Composite PCM Hollow Block Walls and Validation of Phase Transition Heat Transfer Models

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Yuan Zhang ◽  
Sunqi Zhuang ◽  
Qian Wang ◽  
Jiapeng He
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Thermal Performance ◽  
Heat Transfer Process ◽  
Unsteady State ◽  
Typical Structure ◽  
Hollow Block ◽  
Change Material ◽  
Capacity Method ◽  
Transition Heat

A type of concrete hollow block with typical structure and a common phase change material (PCM) were adopted. The PCM was filled into the hollow blocks by which the multiform composite PCM hollow blocks were made. The temperature-changing hot chamber method was used to test the thermal performance of block walls. The enthalpy method and the effective heat capacity method were used to calculate the heat transfer process. The results of the two methods can both reach the reasonable agreement with the experimental data. The unsteady-state thermal performance of the PCM hollow block walls is markedly higher than that of the wall without PCM. Furthermore, if the temperature of the PCM in the wall does not exceed its phase transition temperature range, the PCM wall can reach high thermal performance.

scholarly journals Calculated Study of the Influence of Overheating Aluminum Melt on the Dynamics the Granulation Process

2020 ◽  
pp. 84-93
Author(s):  
Alexander P. Skuratov ◽  
Alexander V. Ivlev ◽  
Artem A. Pianykh
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Solid Phase ◽  
Numerical Study ◽  
Three Dimensional ◽  
Solidification Process ◽  
Square Root ◽  
Effective Heat Capacity ◽  
Granulation Process ◽  
Aluminum Melt

A three-dimensional mathematical model of the solidification process of a liquid metal is considered, taking into account the mobility of the boundaries at which the phase transition is carried out (Stefan boundary value problem). The algorithm of calculation is improved, allowing due to the use of the Dirac δ-function in determining the effective heat capacity to take into account the nonlinearity of the equation of unsteady thermal conductivity and the heat of the phase transition. A numerical study of heat transfer during solidification of lead-containing aluminum melt droplets in air and water is carried out. The influence of droplet size and melt overheating on the solidification dynamics of granules has been studied. An approximate ratio based on the square root law is proposed, taking into account the amount of overheating of the liquid phase and linking the thickness of the formed solid phase with the duration of the granulation process

scholarly journals Numerical simulation and analysis of phase change heat transfer in crude oil

2019 ◽  
pp. 464-464
Author(s):  
Ying Xu ◽  
Xin Nie ◽  
Zhonghua Dai ◽  
Xiao-Yan Liu ◽  
Yang Liu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Transition ◽  
Natural Convection ◽  
Crude Oil ◽  
Phase Change ◽  
Heat Release ◽  
Latent Heat ◽  
Breaking Point ◽  
Latent Heat Release ◽  
Waxy Crude Oil

Accurately obtaining the temperature distribution of the medium in the shutdown pipeline of waxy crude oil has important guiding significance for making maintenance plan and restart plan.The phase transition process of waxy crude oil involves complex problems such as natural convection heat transfer, latent heat release, difficulty in tracing liquid-solid interface. In this paper, the concept and significance of breaking point were proposed. Taking the breaking point and the freezing point as dividing point, and a new zonal partition model was established based on the influence of phase change of crude oil wax crystal on heat transfer mode, with the corresponding governing equations being established for different regions. With the proposed model, the effects of natural convection on heat transfer, latent heat release, location change of condensate reservoir, heat transfer mechanism and other key issues in the process of oil phase transition were analyzed.

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