Numerical and Experimental Investigation of Interface Bonding Via Substrate Remelting of an Impinging Molten Metal Droplet

1996 ◽  
Vol 118 (1) ◽  
pp. 164-172 ◽  
Author(s):  
C. H. Amon ◽  
K. S. Schmaltz ◽  
R. Merz ◽  
F. B. Prinz
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Molten Metal ◽  
Thermal Stresses ◽  
Initial Conditions ◽  
Metal Droplet ◽  
Solid Substrate ◽  
Numerical Results ◽  
Operating Conditions ◽  
Analytical Approaches

A molten metal droplet landing and bonding to a solid substrate is investigated with combined analytical, numerical, and experimental techniques. This research supports a novel, thermal spray shape deposition process, referred to as microcasting, capable of rapidly manufacturing near netshape, steel objects. Metallurgical bonding between the impacting droplet and the previous deposition layer improves the strength and material property continuity between the layers, producing high-quality metal objects. A thorough understanding of the interface heat transfer process is needed to optimize the microcast object properties by minimizing the impacting droplet temperature necessary for superficial substrate remelting, while controlling substrate and deposit material cooling rates, remelt depths, and residual thermal stresses. A mixed Lagrangian–Eulerian numerical model is developed to calculate substrate remelting and temperature histories for investigating the required deposition temperatures and the effect of operating conditions on remelting. Experimental and analytical approaches are used to determine initial conditions for the numerical simulations, to verify the numerical accuracy, and to identify the resultant microstructures. Numerical results indicate that droplet to substrate conduction is the dominant heat transfer mode during remelting and solidification. Furthermore, a highly time-dependent heat transfer coefficient at the droplet/substrate interface necessitates a combined numerical model of the droplet and substrate for accurate predictions of the substrate remelting. The remelting depth and cooling rate numerical results are also verified by optical metallography, and compare well with both the analytical solution for the initial deposition period and the temperature measurements during droplet solidification.

Numerical Analysis on the Impact Behavior of Molten Metal Droplets Using a Modified Splat-Quench Solidification Model

2004 ◽  
Vol 126 (6) ◽  
pp. 1014-1022 ◽  
Author(s):  
D. Sivakumar ◽  
H. Nishiyama
Keyword(s):  
Molten Metal ◽  
Initial Conditions ◽  
Metal Layer ◽  
Metal Droplet ◽  
Solid Substrate ◽  
Impact Behavior ◽  
Solidification Model ◽  
Numerical Predictions ◽  
Model Predictions ◽  
The Impact

A simple model is formulated for the analysis of the spreading and solidification processes of a molten metal droplet impinging on a solid substrate. At the first stage, the model evaluates the diameter and the radial velocity of the spreading molten metal layer at the instant t0=D/W from the start of impact using analytical relations. Here D and W are, respectively, the diameter and the velocity of the impinging droplet. Numerical predictions on the evolution of the spreading metal layer are obtained by using a modified splat-quench solidification model with initial conditions described at the instant t0=D/W. The model predictions are compared with the experimental data available from the literature. A systematic parametric study is carried out to illustrate the model predictions at different impinging conditions.

A Study on Evolution of Splat Radius and Temperature in Thermal Spray Process

2018 ◽  
Author(s):  
Manpreet Dash ◽  
Sangharsh Kumar ◽  
Partha Pratim Bandyopadhyay ◽  
Anandaroop Bhattacharya
Keyword(s):  
Heat Transfer ◽  
Thermal Spray ◽  
Molten Metal ◽  
Spray Deposition ◽  
Substrate Surface ◽  
Metal Droplet ◽  
Droplet Impingement ◽  
Impact Process ◽  
The Impact ◽  
Maximum Spreading

The impact process of a molten metal droplet impinging on a solid substrate surface is encountered in several technological applications such as ink-jet printing, spray cooling, coating processes, spray deposition of metal alloys, thermal spray coatings, manufacturing processes and fabrication and in industrial applications concerning thermal spray processes. Deposition of a molten material or metal in form of a droplet on a substrate surface by propelling it towards it forms the core of the spraying process. During the impact process, the molten metal droplet spreads radially and simultaneously starts losing heat due to heat transfer to the substrate surface. The associated heat transfer influences impingement behavior. The physics of droplet impingement is not only related to the fluid dynamics, but also to the respective interfacial properties of solid and liquid. For most applications, maximum spreading diameter of the splat is considered to be an important factor for droplet impingement on solid surfaces. In the present study, we have developed a model for droplet impingement based on energy conservation principle to predict the maximum spreading radius and the radius as a function of time. Further, we have used the radius as a function of time in the heat transfer equations and to study the evolution of splat-temperature and predict the spreading factor and the spreading time and mathematically correlate them to the spraying parameters and material properties.

Experimental and Numerical Investigation of Heat Transfer Characteristics of Liquid Flow With Micro-Encapsulated Phase Change Material

2008 ◽  
Author(s):  
Rami Sabbah ◽  
Jamal Yagoobi ◽  
Said Al Hallaj
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Pressure Drop ◽  
Phase Change ◽  
Phase Change Material ◽  
Operating Conditions ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Encapsulated Phase Change Material ◽  
Change Material

This experimental and numerical study investigates Micro-Encapsulated Phase Change Material (MEPCM) heat transfer characteristics and corresponding pressure drop. To conduct this study, an experimental setup consisting of a steel tube with an inner diameter of 4.3mm, outer diameter of 6.5mm and a length of 1,016mm is selected. A MEPCM mass concentration of 20% slurry with particle diameter ranging between 5–15μm is included in this study. Tube wall temperature profile, fluid inlet, outlet temperatures, the pressure drop across the tube are measured and corresponding Nusselt number are determined for various operating conditions. The experimental results are used to validate the numerical model predictions. The numerical model results show good agreement with the experimental data under various operating conditions. The controlling parameters are identified and their effects on the heat transfer characteristics of micro-channels with MEPCM slurries are evaluated.

A Numerical Simulation on the Fluid Flow and Heat Transfer Around a Vehicle in a Paint Drying Process

2013 ◽  
Author(s):  
Jongrak Choi ◽  
Nahmkeon Hur ◽  
Hee-Soo Kim
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Fluid Flow ◽  
Moving Boundary ◽  
Numerical Results ◽  
Operating Conditions ◽  
Drying Process ◽  
Automotive Manufacturing ◽  
Flow And Heat Transfer ◽  
Paint Drying

In the automotive manufacturing process, the paint drying process is very important to improve the appearance of the vehicle. In the present study, the fluid flow and heat transfer around a vehicle were numerically investigated for the purpose of predicting the drying performance of the paint drying process. In order to simulate the operating conditions of the paint drying process, the following techniques were used: relative moving boundary conditions, multiple reference frames, and conjugated heat transfer. The present numerical method was verified by comparing the numerical results of the temperature at several monitoring points on a vehicle, while using the experimental data. To evaluate the drying performance quantitatively, the absorbed heat energy that is closely related to the drying of paint was obtained from the numerical simulation. It was found that the drying performance is greatly affected by operating conditions such as the temperature and flow rate of blowing air. To improve the drying performance, the operating conditions of the paint drying process were optimized using the numerical results of various operating conditions.

Three-Dimensional Surface Heat Transfer Coefficient and Thermal Stress Analysis for Ceramics Tube Dipping into Molten Metal

2010 ◽  
Vol 452-453 ◽  
pp. 233-236 ◽  
Author(s):  
Yasushi Takase ◽  
Wen Bin Li ◽  
Hendra ◽  
Hiroki Ogura ◽  
Yusuke Higashi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Stress ◽  
Transfer Coefficient ◽  
Molten Metal ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Surface Heat ◽  
Surface Heat Transfer ◽  
Surface Heat Transfer Coefficient

The low pressure die casting machine has been used in industries because of its low-cost and high efficiency precision forming technique. In the low pressure die casting process is that the permanent die and filling systems are placed over the furnace containing the molten alloy. The filling of the cavity is obtained by forcing the molten metal, by means of a pressurized gas, to rise into a ceramic tube, which connects the die to the furnace. The ceramics tube, called stalk, has high temperature resistance and high corrosion resistance. However, attention should be paid to the thermal stress when the ceramics tube is dipped into the molten metal. It is important to reduce the risk of fracture that may happen due to the thermal stresses. To calculate the thermal stress, it is necessary to know the surface heat transfer coefficient when the ceramics tube dips into the molten metal. In this paper, therefore, the three-dimensional thermo-fluid analysis is performed to calculate surface heat transfer coefficient correctly. The finite element method is applied to calculate the thermal stresses when the tube is dipped into the crucible with varying dipping speeds and dipping directions. It is found that the thermal stress can be reduced by dipping slowly when the tube is dipped into the molten metal.

Microchannel Optimization for Heat Dissipation From a Solid Substrate

2008 ◽  
Author(s):  
C. B. Sobhan ◽  
P. S. Anoop ◽  
Kuriyan Arimboor ◽  
Thomas Abraham ◽  
G. P. Peterson
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Thermal Resistance ◽  
Computational Model ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Heat Dissipation ◽  
Three Dimensional ◽  
Solid Substrate ◽  
Nusselt Numbers

A computational model was developed to analyze and optimize the convective heat transfer for water flowing through rectangular microchannels fabricated in a silicon substrate. A baseline case was analyzed by solving the nondimensional governing equations. Using a quasi three-dimensional computational model, the velocity and temperature distributions were obtained and the numerical results were then used to determine the overall dimensionless thermal resistance for the convective heat transfer from the substrate to the fluid. To validate the numerical model, the average Nusselt numbers as determined by the numerical model were compared with experimental results available in the literature, for channels with comparable hydraulic diameters. The procedure for arriving at an optimum geometric configuration and arrangement of microchannels on the substrate, subject to given design constraints, so that the thermal resistance is at a minimum, is described and demonstrated using the computational model.

Modeling Heat Transfer of the Air Gap between Human Body and Clothing

2011 ◽  
Vol 332-334 ◽  
pp. 1611-1614
Author(s):  
Ying Ke ◽  
Yun Yi Wang ◽  
Jun Li
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Numerical Model ◽  
Human Skin ◽  
Human Body ◽  
Air Gap ◽  
Numerical Results ◽  
Unsteady State ◽  
State Heat ◽  
Set Up

An unsteady-state heat transfer numerical model of the microclimate between human skin and clothing is set up. Air-gap thickness less than 17mm is considered. Matlab pde toolbox is chosen to compute the numerical model. The numerical results of the model agrees well with a set of published experimental data.

scholarly journals The Effect of Heat Transfer and Polymer Concentration on Non-Newtonian Fluid from Pore-Scale Simulation of Rock X-Ray micro-CT

2017 ◽  
Author(s):  
Moussa Tembely ◽  
Ali M. AlSumaiti ◽  
Mohamed S. Jouini ◽  
Khurshed Rahimov
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Newtonian Fluid ◽  
Polymer Concentration ◽  
Isothermal Condition ◽  
Operating Conditions ◽  
Flow Index ◽  
Micro Ct ◽  
Pore Scale ◽  
Fluid Rheology

Most of the pore-scale imaging and simulations of non-Newtonian fluid are based on the simplifying geometry of network modeling and overlook the fluid rheology and heat transfer. In the present paper, we developed a non-isothermal and non-Newtonian numerical model of the flow properties at pore-scale by direct simulation of the 3D micro-CT images using a Finite Volume Method (FVM). The numerical model is based on the resolution of the momentum and energy conservation equations. Owing to an adaptive meshing technique and appropriate boundary conditions, rock permeability and mobility are accurately computed. A temperature and concentration-dependent power-law viscosity model in line with the experimental measurement of the fluid rheology is adopted. The model is first applied at isothermal condition to 2 benchmark samples, namely Fontainebleau sandstone and Grosmont carbonate, and is found to be in good agreement with the Lattice Boltzmann method (LBM). Finally, at non-isothermal conditions, an effective mobility is introduced that enables to perform a numerical sensitivity study to fluid rheology, heat transfer, and operating conditions. While the mobility seems to evolve linearly with polymer concentration, the effect of the temperature seems negligible by comparison. However, a sharp contrast is found between carbonate and sandstone under the effect of a constant temperature gradient. Besides concerning the flow index and consistency factor, a good master curve is derived when normalizing the mobility for both the carbonate and the sandstone.

scholarly journals Thermal behavior of phase change material (PCM) based cavity: experimental and numerical validation

2021 ◽  
Author(s):  
Md Ali Ahamed Shak
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Thermal Behavior ◽  
Phase Change ◽  
Thermal Energy ◽  
Numerical Results ◽  
Rectangular Cavity ◽  
Hot Water ◽  
Heating Source ◽  
Shaped Tube

Recently, thermal energy storage (TES) includes technologies for collecting and storing energy for later use in domestic and industry by using Phase Change Materials (PCMs) which is a main topic for many researchers. In this experimental and numerical study, melting process and thermal behavior due to a U-shaped heat source embedded in the PCM is investigated which has been simulated in COMSOL-3D Multiphysics. The three-dimensional governing equation is solved for the fluid flow and heat transfer behavior. Two different cases are analyzed in this study. In the first case, the experimental results of a rectangular cavity filled with PCM, and a Ushaped heating source embedded in it is validated with a numerical model. PCM is used that has melting point temperature 32 °C, and flow of water at temperature 39 °C for six hours period through the U-shaped tube to intensify the PCM`s temperature. PCM melts and absorbs latent heat as energy which is analyzed horizontally and vertically. PCMs temperature increased uniformly with increasing of time inside the cavity. The melting rate was high around the heating source than the far distances of heating source. After six hours, 100% PCM was melted around the U-shaped tube, however, far from the U-shaped tube was not significantly melted in both experimental study and numerical model. The numerical results are in good agreement with the experimental data with a small number of relative error in all cases. In the second case, PCM and Bentonite are used in four different models in the same rectangular cavity, then hot-water and, cold-water flowing through the U-shaped tube, and the numerical results were validated for all models. It was observed that, when Bentonite is used, the heat transfer rate was higher compare to the case when PCM is used for anywhere in the cavity. The reason is that, Bentonite has higher thermal conductivity and temperature gradient than the PCM. So, Bentonite was more sensitive for heat transfer whenever used in heating or cooling. It is clear from this study that PCM and Bentonite can be a good media for storing thermal energy for later use such as room heating, space heating, industrial and commercial uses. PCM has a great possibility to it, because of its low initial and maintenance cost, and its availability.

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