Modeling of Evaporation Phenomenon Considering Liquid and Vapor Phase Conduction Effects: Stefan Problems

2016 ◽  
Author(s):  
Isaac Perez-Raya ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Stefan Problem ◽  
Current Approach ◽  
Numerical Code ◽  
Transfer Model ◽  
Ansys Fluent ◽  
Stefan Problems ◽  
Realistic Representation ◽  
Interface Displacement ◽  
Liquid Heat

In developing numerical code for interfacial evaporation problems, 1st Stefan problem is generally used for validation. In this paper, both 1st and 2nd Stefan problems are used for validating a numerical code that utilizes volume of fluid method and is based on ANSYS-Fluent along with user defined functions (UDFs) to account for the mass and energy transfer at the interface. The 2nd Stefan problem incorporates heat transfer in both phases and provides a more realistic representation of an evaporating interface. Emphasis is put on the vapor-liquid heat transfer, which takes into account the sensible heat transfer in the liquid phase where liquid conduction effects are important. The mass transfer model takes into account the temperature gradients in both phases at the interface. Analytical solutions for the two Stefan problems are reported and used for validation purposes. Results show that the interface displacement and temperature distributions are simulated accurately. The current approach utilizes the robust platform of ANSYS-Fluent while allowing an accurate representation of the phase change processes at the interface.

scholarly journals Numerical Modelling Of Humid Air Flow Around A Porous Body

2015 ◽  
Vol 9 (3) ◽  
pp. 161-166
Author(s):  
Aneta Bohojło-Wiśniewska
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Porous Medium ◽  
Numerical Modelling ◽  
Chinese Cabbage ◽  
Air Flow ◽  
Transfer Model ◽  
Humid Air ◽  
Ansys Fluent ◽  
Complex Heat Transfer

Summary This paper presents an example of humid air flow around a single head of Chinese cabbage under conditions of complex heat transfer. This kind of numerical simulation allows us to create a heat and humidity transfer model between the Chinese cabbage and the flowing humid air. The calculations utilize the heat transfer model in porous medium, which includes the temperature difference between the solid (vegetable tissue) and fluid (air) phases of the porous medium. Modelling and calculations were performed in ANSYS Fluent 14.5 software.

Multiphysics Modeling and Simulation of an Arc-Jet Sprayer

2021 ◽  
Author(s):  
Juan J. Campos Manzo ◽  
Nicole Wagner ◽  
Kevin R. Anderson
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Substrate Surface ◽  
Arc Spraying ◽  
Process Conditions ◽  
Transfer Model ◽  
Ansys Fluent ◽  
Numerical Heat Transfer ◽  
Twin Wire Arc Spraying ◽  
Wire Arc Spraying

Abstract Twin wire arc spraying (TWAS) is a plasma spraying process that offers low workpiece heating and high deposition rates at a lower cost. Variations in TWAS process conditions cause the substrate temperature to fluctuate and even melt. Therefore, the motivation of this project was to simulate the heat transfer from the TWAS torch to the substrate during spraying and layer formation of a coating. Simulations using ANSYS FLUENT Computational Fluid Dynamics (CFD) software were used to model the heat transfer in a TWAS system. The results of this paper are meant to augment and improve the database of TWAS technology. A CFD numerical heat transfer model is presented that was used to investigate the substrate surface temperature during the TWAS process. The results for the different pressure models showed that for a 3 second simulation, substrate surface temperatures increased as nozzle inlet pressure was decreased. For the upper and lower bound pressures of 75 psia and 29 psia, substrate surface temperature resulted in 946 °C and 1010 °C, respectively.

Investigation of Mechanism for a Thermal Cloak Metamaterial by an Entropy Production Approach

2016 ◽  
Author(s):  
H.-C. Zhang ◽  
H.-Y. Yu ◽  
Y. Li ◽  
N.-Q. Song ◽  
Y.-Q. Wei
Keyword(s):  
Heat Transfer ◽  
Layer Structure ◽  
Fundamental Principle ◽  
Heat Transfer Process ◽  
Transfer Model ◽  
Ansys Fluent ◽  
Energy Aspect ◽  
Protected Object ◽  
Fluent Software ◽  
Good Heat

With the development of metamaterials, microscale thermal cloak attracted many researchers’ attention. It was found that a thermodynamic cloak has unique characteristics of heat transfer transformation, with fundamental principle of transformation optics applied in thermodynamic field. An overview of thermal cloak related studies have not explained the physical mechanism in view of energy aspect. In the current work, two-dimensional heat transfer model of a multilayer thermal cloak was investigated through simulation according to Schittny’s microstructured model as well as an only polydimethylsiloxane protected layer model and plate model as control groups. Numerical simulations were developed with ANSYS FLUENT software for three models respectively in the process of heating to analysis the heat transfer and stealth protection during transient heat transfer process. The simulation results were agreed well with other’s previous experiment results on temperature distribution. The cloaking mechanism was analyzed by entropy generation approaches, and deriving the thermodynamics explanation at the aspect of the energy transfer. Thermodynamic cloak structure has a good heat stealth effect on the process of heat transfer, without the effecting outside the protected object on the distribution of both temperature and energy. Thermodynamic cloak control the energy dissipation inside the multi-layer structure, but the maximum dissipation position was shifted along the heat transfer processing.

scholarly journals Pairing Directional Solar Inputs From Ray Tracing to Solar Receiver/Reactor Heat Transfer Models on Unstructured Meshes: Development and Case Studies

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
H. Evan Bush ◽  
Andrew J. Schrader ◽  
Peter G. Loutzenhiser
Keyword(s):  
Heat Transfer ◽  
Monte Carlo ◽  
Case Studies ◽  
Ray Tracing ◽  
Three Dimensional ◽  
Transfer Model ◽  
Reactor Model ◽  
Ansys Fluent ◽  
Ray Tracing Model ◽  
Transfer Models

Abstract A novel method for pairing surface irradiation and volumetric absorption from Monte Carlo ray tracing to computational heat transfer models is presented. The method is well-suited to directionally and spatially complex concentrated radiative inputs (e.g., solar receivers and reactors). The method employs a generalized algorithm for directly mapping absorbed rays from a Monte Carlo ray tracing model to boundary or volumetric source terms in the computational mesh. The algorithm is compatible with unstructured, two and three-dimensional meshes with varying element shapes. Four case studies were performed on a directly irradiated, windowed solar thermochemical reactor model to validate the method. The method was shown to conserve energy and preserve spatial variation when mapping rays from a Monte Carlo ray tracing model to a computational heat transfer model in ansys fluent.

scholarly journals Pairing Directional Solar Inputs From Ray Tracing to Solar Receiver/Reactor Heat Transfer Models on Unstructured Meshes: Development and Case Studies

2020 ◽  
Author(s):  
H. Evan Bush ◽  
Andrew J. Schrader ◽  
Peter G. Loutzenhiser
Keyword(s):  
Heat Transfer ◽  
Case Studies ◽  
Ray Tracing ◽  
Three Dimensional ◽  
Transfer Model ◽  
Reactor Model ◽  
Ansys Fluent ◽  
Computational Mesh ◽  
Ray Tracing Model ◽  
Transfer Models

Abstract A novel method for pairing surface irradiation and volumetric absorption from ray tracing to computational heat transfer models is presented. The method is well-suited to directionally and spatially-complex concentrated radiative inputs, such as in solar receivers and reactors. The method employs a generalized algorithm for directly mapping absorbed rays from the ray tracing model to boundary or volumetric source terms in the computational mesh. The algorithm is compatible with unstructured, two and three-dimensional meshes with varying element shapes. To validate the method, four case studies were performed on a directly irradiated, windowed solar thermochemical reactor model. The method was shown to be energy conservative and to preserve spatial variation when mapping rays from a Monte Carlo ray tracing model to the computational heat transfer model in ANSYS Fluent.

Study on Mechanisms and Model of Heat Transfer in Spray Cooling

2005 ◽  
Author(s):  
Shu-Ye Lei ◽  
Qiu-Min Lu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Dissipation ◽  
Pure Water ◽  
Spray Cooling ◽  
Transfer Model ◽  
Analysis Model ◽  
Transfer Coefficients ◽  
Liquid Heat

The paper presented two heat transfer coefficients: apparent heat transfer coefficient and real heat transfer coefficient. Apparent HTC is overall HTC, which is affected by many factors, such as liquid heat dissipation; on the other hand, real HTC is the HTC between heater and liquid film, which only relates to spray momentum. Local spray cooling experiments and PDA measurement experiments were conducted and the real heat transfer empirical correlation was developed. A half empirical and half analysis model involving the heat dissipation is acquired. At last, experimental apparent HTC was compared with the computed value to check the heat transfer model. It is shown that it is possible to predict HTC with pure water coolant and full cone sprays for non-boiling spray cooling.

Theoretical Post-Dryout Heat Transfer Model

2018 ◽  
Vol 1 (1) ◽  
pp. 142-150
Author(s):  
Murat Tunc ◽  
Ayse Nur Esen ◽  
Doruk Sen ◽  
Ahmet Karakas
Keyword(s):  
Heat Transfer ◽  
Droplet Diameter ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Operating Pressure ◽  
Vertical Pipe ◽  
Two Phase ◽  
Experimental Values ◽  
Reactor Operating ◽  
Coolant System

A theoretical post-dryout heat transfer model is developed for two-phase dispersed flow, one-dimensional vertical pipe in a post-CHF regime. Because of the presence of average droplet diameter lower bound in a two-phase sparse flow. Droplet diameter is also calculated. Obtained results are compared with experimental values. Experimental data is used two-phase flow steam-water in VVER-1200, reactor coolant system, reactor operating pressure is 16.2 MPa. On heater rod surface, dryout was detected as a result of jumping increase of the heater rod surface temperature. Results obtained display lower droplet dimensions than the experimentally obtained values.

Sign in / Sign up

Export Citation Format

Share Document