Temperature Field Analysis of Directional Solidification of Multi-Crystalline Silicon

2013 ◽  
Vol 750 ◽  
pp. 96-99 ◽  
Author(s):  
Yan Hu ◽  
Hai Hao ◽  
Xiao Teng Liu
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Solar Cells ◽  
Directional Solidification ◽  
Crystalline Silicon ◽  
Cost Effective ◽  
Field Analysis ◽  
Temperature Fields ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

A cost effective directional solidification (DS) technique is one of the main methods to produce multi-crystalline silicon (mc-Si) ingots for solar cells. A detailed understanding of the DS process is very important to control the formation and distribution of impurities, precipitates, thermal stress and dislocation defects in an ingot. All these factors have direct effects on the solar cells efficiency. The quality of crystal grown by DS is largely determined by the temperature field. In order to optimize the technique parameters and obtain high quality silicon ingots, the temperature fields with different heat transfer coefficients at different positions have been calculated during the silicon DS process. The influence of the heat transfer coefficients at the ingot top(ht), the ingot bottom (hb), and between ingot and crucible (hs) on the DS process of mc-Si have been analyzed. The calculation results may provide important theoretical basis for optimizing technological recipe in the productive practice.

Numerical Simulation on the Temperature Field of Steel 1045 Quenched by Different Hardening Media

2013 ◽  
Vol 444-445 ◽  
pp. 1222-1228
Author(s):  
Jian Bin Xie ◽  
Chang Chang Wu ◽  
Jing Fan ◽  
Miao Fu ◽  
Deng Feng Hu
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Temperature Field ◽  
Temperature Fields ◽  
Cooling Curves ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Heat Transfer Theory ◽  
Quenching Process ◽  
Estimate Method

Based on the experimental measured cooling curves and the boiling heat transfer theory, the inverse problem of nonlinear heat conduct equation for Steel 1045 quenched by different hardening media was established by functional analysis and finite element method, and the surface heat-transfer coefficients in continuous cooling during quenching were calculated by nonlinear estimate method. Then the constitutive model of Steel 1045 during quenching was established subsequently. Finally, the temperature field of Steel 1045 cylinder quenched by different hardening media was simulated by Finite Element Methods (FEM). Results show that the calculated temperature fields agree with the practical quenching process.

The Effect of Regulating Elements on Convective Heat Transfer along Shaped Heat Exchange Surfaces

2013 ◽  
Vol 34 (1) ◽  
pp. 5-16 ◽  
Author(s):  
Jozef Cernecky ◽  
Jan Koniar ◽  
Zuzana Brodnianska
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Cfd Simulation ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Temperature Fields ◽  
Transfer Coefficients ◽  
Heat Transfer Intensification ◽  
Heat Transfer Coefficients ◽  
Forced Air

Abstract The paper deals with a study of the effect of regulating elements on local values of heat transfer coefficients along shaped heat exchange surfaces with forced air convection. The use of combined methods of heat transfer intensification, i.e. a combination of regulating elements with appropriately shaped heat exchange areas seems to be highly effective. The study focused on the analysis of local values of heat transfer coefficients in indicated cuts, in distances expressed as a ratio x/s for 0; 0.33; 0.66 and 1. As can be seen from our findings, in given conditions the regulating elements can increase the values of local heat transfer coefficients along shaped heat exchange surfaces. An optical method of holographic interferometry was used for the experimental research into temperature fields in the vicinity of heat exchange surfaces. The obtained values correspond very well with those of local heat transfer coefficients αx, recorded in a CFD simulation.

Flow Dynamics Over Two Cylinders in Tandem Subjected to Different Heating Cases

2021 ◽  
Author(s):  
Rami Homsi ◽  
MD Islam ◽  
Yap Yit Fatt ◽  
Isam Janajreh
Keyword(s):  
Heat Transfer ◽  
Cross Flow ◽  
Temperature Fields ◽  
Circular Cylinders ◽  
Transfer Coefficients ◽  
Extended Body ◽  
Heat Transfer Coefficients ◽  
Velocity Magnitude ◽  
Fluid Properties ◽  
Limiting Case

Abstract Heated and unheated flows with forced convection over two fixed circular cylinders in tandem are studied numerically for 80 ≤ Re ≤ 250 and 1 ≤ T* ≤ 2.3. Three different spacing ratios (L/D) = [2, 4, 8] are considered under three heating conditions. The scenarios considered are (1) heated upstream and unheated downstream cylinders, (2) unheated upstream and heated downstream cylinders and (3) heated upstream and downstream cylinders. These scenarios represent the limiting case for a cross-flow heat exchanger, where the downstream tubes are at increasingly lower or higher temperature for cooling or heating, respectively. The global aerodynamic forces on the cylinder as vortices shed was investigated. The flow is visualized by plotting the streamlines, temperature fields, and velocity magnitude contours for the different spacing ratios and compared to the flow regimes in literature namely, Extended-body, Reattachment, and Co-shedding regimes. The drag and surface heat transfer coefficients are analyzed for different scenarios. The effect of heating on the fluid properties and the resulted wakes in the flow are found to be strongly influenced by Re and L/D. The scenario of heated upstream and unheated downstream cylinders was found to increase the mean drag coefficient Cd on the upstream cylinder for L/D = 2 & 4 but is not as evident for the downstream cylinder. The heat transfer coefficient h on the upstream cylinder remained approximately the same regardless of a heated or unheated downstream cylinder. In contrast, h of the downstream cylinder decreases for the scenario of heated upstream and downstream cylinder.

Effect of Rotation and Coolant Throughflow on the Heat Transfer and Temperature Field in an Enclosure

1976 ◽  
Vol 98 (3) ◽  
pp. 387-394 ◽  
Author(s):  
E. M. Sparrow ◽  
Leonardo Goldstein
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Flow Rate ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Transfer Coefficients ◽  
Disk System ◽  
Heat Transfer Coefficients

Measurements were performed to determine the local heat transfer coefficients along the heated shroud of a shrouded parallel disk system. The temperature field within the enclosure formed by the shroud and the disks was also measured. One of the disks was rotating, whereas the other disk and the shroud were stationary. Coolant air was introduced into the enclosure through an aperture at the center of the stationary disk and exited through a slot at the rim of the rotating disk. The coolant entrance-exit arrangement differed from that of previous studies, with the additional difference that the incoming coolant stream was free of rotation. The coolant flow rate, the disk rotational speed, and the aspect ratio of the enclosure were varied during the experiments. The heat transfer coefficients were found to be increasingly insensitive to the absence or presence of rotation as the coolant flow rate increased. There was a general increase of the transfer coefficients with increasing coolant flow rate, especially for low rotational speeds. The temperature field in the enclosure differed markedly depending on the relative importance of rotation and of coolant throughflow. When the latter dominates, the temperature in the core is relatively uniform, but in the presence of strong rotation there are significant nonuniformities. A comparison was made between the present Nusselt number results and those of prior experiments characterized by different coolant entrance—exit arrangements. The positioning of the coolant exit slot relative to the direction of the boundary layer flow on the shroud emerged as an important factor in the comparison.

Inverse Determination of Steady Heat Convection Coefficient Distributions

1998 ◽  
Vol 120 (2) ◽  
pp. 328-334 ◽  
Author(s):  
T. J. Martin ◽  
G. S. Dulikravich
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Boundary Conditions ◽  
Measurement Data ◽  
Cost Effective ◽  
Heat Fluxes ◽  
Transfer Coefficients ◽  
Simple Modification ◽  
Heat Transfer Coefficients ◽  
Thermal Boundary Conditions

An inverse Boundary Element Method (BEM) procedure has been used to determine unknown heat transfer coefficients on surfaces of arbitrarily shaped solids. The procedure is noniterative and cost effective, involving only a simple modification to any existing steady-state heat conduction BEM algorithm. Its main advantage is that this method does not require any knowledge of, or solution to, the fluid flow field. Thermal boundary conditions can be prescribed on only part of the boundary of the solid object, while the heat transfer coefficients on boundaries exposed to a moving fluid can be partially or entirely unknown. Over-specified boundary conditions or internal temperature measurements on other, more accessible boundaries are required in order to compensate for the unknown conditions. An ill-conditioned matrix results from the inverse BEM formulation, which must be properly inverted to obtain the solution to the ill-posed problem. Accuracy of numerical results has been demonstrated for several steady two-dimensional heat conduction problems including sensitivity of the algorithm to errors in the measurement data of surface temperatures and heat fluxes.

Temperature Field Analysis on Cooling Stave Material and Stave Body

2011 ◽  
Vol 130-134 ◽  
pp. 931-934
Author(s):  
Fang Wei ◽  
Jiang Chang
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Blast Furnace ◽  
Structure Design ◽  
Field Analysis ◽  
Temperature Fields ◽  
Temperature Field Distribution ◽  
The Relationship ◽  
Account Temperature ◽  
General Method

The cooling stave longevity is the most important factor to affect the blast furnace life. In this paper the cooling stave model was built by use of software ANSYS. With boundary conditions of heat transfer of cooling stave fully taken into account, temperature fields of cooling stave made of different materials are analyzed. The analysis results showed the relationship between the different cooling stave materials and temperature field distribution of stave body. A general method of selecting cooling stave material and structure design for longevity design of cooling stave was developed.

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