Optimization of Organ Freezing Protocols With Specified Allowable Thermal Stress Levels

2000 ◽  
Author(s):  
Brian H. Dennis ◽  
George S. Dulikravich ◽  
Yoed Rabin
Keyword(s):  
Temperature Distribution ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Genetic Optimization ◽  
Local Cooling ◽  
Temperature Dependent ◽  
Nonlinear Constrained Optimization ◽  
Unsteady Heat Conduction ◽  
Novel Concept ◽  
Cryo Preservation

Abstract A novel concept of determining optimized cooling protocols for freezing three-dimensional organs has been developed and its feasibility examined computationally. The concept is based on determining correct spatial variation of temperature distribution on the walls of a freezing container at every instant of time during the cooling process so that local thermal stresses in the heterogeneous organ are always kept below a specified level while maximizing the local cooling rates. The cryo-preservation medium must be gelatin which prevents thermal convection. The optimized cooling protocol was simulated by developing a time-accurate finite element computer program to predict unsteady heat conduction with phase change and thermal stresses within a realistically shaped and sized organ made of tissues with temperature-dependent physical properties. A micro-genetic optimization algorithm was then used to achieve nonlinear constrained optimization of parameterized time-varying container wall temperature distribution so that the prescribed maximum allowable thermal stresses are never exceeded in the organ.

Design Optimization of Induction Heater in Planetary Reactors for Semiconductor Industry

2015 ◽  
Vol 792 ◽  
pp. 505-510 ◽  
Author(s):  
Aleksandr Nikanorov ◽  
Bernard Nacke ◽  
Tatiana Zedler
Keyword(s):  
Temperature Distribution ◽  
Thermal Stresses ◽  
Semiconductor Industry ◽  
Three Dimensional ◽  
Induction Coil ◽  
Temperature Dependent ◽  
Thermal Calculations ◽  
Three Dimensional Models ◽  
Account Temperature ◽  
Coil Shape

One application of induction heating is a planetary reactor for deposition of compound semiconductor layers from the gas phase. High temperature needed for the process is provided by a “pancake” induction coil. Temperature distribution in the reactor influences the deposition quality as well as the lifetime of the reactor components. The induction coil shape has been improved by numerical modelling combined with automatic optimization. The developed two-and three-dimensional models include coupled electromagnetic and thermal calculations to take into account temperature dependent material properties. Three-dimensional structural analysis, based on the predicted temperature distribution, was used to estimate the level of the appeared thermal stresses in the reactor parts. The received optimal design of the induction coil has been successfully tested in the industrial planetary reactor.

Numerical Simulation Investigation on Single-Layer Multi-Tracks Laser Milling of Al2O3 Ceramic

2014 ◽  
Vol 971-973 ◽  
pp. 111-114
Author(s):  
Zhao Mei Xu ◽  
Zong Hai Hong ◽  
Qing An Wang ◽  
Hai Bing Wu
Keyword(s):  
Temperature Distribution ◽  
Laser Beam ◽  
Parametric Design ◽  
Three Dimensional ◽  
Single Layer ◽  
Element Model ◽  
Temperature Dependent ◽  
Laser Milling ◽  
Transient Thermal ◽  
Account Temperature

Regional-input high-power laser beam inevitably leads to inhomogeneous and instable temperature distribution of laser milling(LM) process. Knowledge of thermal of multi-track LM is critical to understand the interaction of different milling tracks. Taking into account temperature-dependent thermal conduction and heat capacity, a three-dimensional transient thermal finite element model has been developed. The moving laser beam is simulated with the employment of ANSYS parametric design language and latent heat is considered by using enthalpy. Several conclusions according to the simulation results were produced, comparing with the previous track, the latter one has larger heat affected region and larger in homogeneous temperature distribution; the greatest temperature gradient takes place near the edges of milling part where the scanning direction changes.

Thermal Stresses in Thick-Walled Circular Cylinders Under Axisymmetric Temperature Distribution

1971 ◽  
Vol 93 (4) ◽  
pp. 969-975 ◽  
Author(s):  
K. W. Yang ◽  
C. W. Lee
Keyword(s):  
Temperature Distribution ◽  
Thin Shell ◽  
Shell Theory ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Circular Cylinders ◽  
Curved Surfaces ◽  
Present Solution ◽  
Axisymmetric Temperature ◽  
Thin Shell Theory

A series solution is obtained for thick-walled cylinders subjected to a temperature distribution which varies both radially and axially. The solution is based on three-dimensional linear theory of thermoelasticity, with appropriate approximations by neglecting small terms and using St. Venant’s principle. The internal and external curved surfaces are assumed traction-free. In each series of the solution the first term is identical to the thin shell theory and the subsequent correcting terms are expressed in increasing powers of the thickness-to-radius ratio. An illustrative example problem is solved by using the present solution, and the numerical results are compared with those based on the thin shell theory.

scholarly journals MAXIMUM ALLOWABLE THERMAL STRESSES CALCULATION OF WATER TUBE BOILER DURING OPERATION

2019 ◽  
Vol 7 (7) ◽  
pp. 191-199
Author(s):  
Asa Elmaryami ◽  
Abdulla Sousi ◽  
Walid Saleh ◽  
Sharefa El-Mabrouk Abd El-Mawla ◽  
Mohamed Elshayb
Keyword(s):  
Temperature Distribution ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Industrial Sector ◽  
Limiting Factors ◽  
Steam Boiler ◽  
Two Dimensional ◽  
Water Tube ◽  
Cartesian Coordinate ◽  
Tube Life

In steam boiler industrial sector, pressure and temperature of the water tube are the two main factors that affecting the safety and efficiency of a steam boiler. Explosions may be occurring because of a sudden drop in pressure without a corresponding drop in temperature. Therefore, understanding the temperature distribution of the water tube boiler is essential control the failure and explosion of the boiler. Once the temperature distribution is known then the limiting factors that affect the water tube life such as maximum allowable thermal stresses can be determined. ANSYS software will be used to determine the temperature distribution in the water tube of a utility boiler during operation at elevated inlet water and furnace temperature. The theory of axisymmetric has been utilized since water- tube is cylindrical in shape. In axisymmetric theory, a three-dimensional cylindrical problem like water tube can be reduced to two dimensional by ignoring the circumferential Ө, while r-axis and z-axis became x-axis and y-axis or Cartesian coordinate. Then two-dimensional rectangular elements meshing for the profile cross-section along the water tube in r and z axes were implemented in a computerize simulation using ANSYS 10 to find out the steady state temperature distribution of the water tube.

A photothermoelastic investigation of transient thermal stresses in wing ribs

1972 ◽  
Vol 7 (2) ◽  
pp. 117-124 ◽  
Author(s):  
E Matsumoto ◽  
S Sumi ◽  
T Sekiya
Keyword(s):  
Temperature Distribution ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Composite Model ◽  
New Technique ◽  
Transient Temperature ◽  
Transient Temperature Distribution ◽  
Transient Thermal

The photothermoelastic method of refrigeration has been used to study the problem of a long beam under transient temperature distribution and good correlation with the theoretical values has been obtained. The new technique for three-dimensional photothermoelasticity, which uses a composite model made of photoelastically sensitive and insensitive materials, is suggested for the analysis of idealized wing-rib structures.

Predicting Residual Thermal Stresses in Friction Stir Welding

2003 ◽  
Author(s):  
Mir H. Zahedul Khandkar ◽  
Jamil A. Khan
Keyword(s):  
Friction Stir Welding ◽  
Residual Stresses ◽  
Thermal Model ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Welding Process ◽  
Temperature History ◽  
Temperature Dependent ◽  
Friction Stir ◽  
Input Torque

Sequentially coupled finite element models of the friction stir welding process have been proposed to study the residual stresses caused by the thermal cycles during friction stir welding of metals. This is a two step simulation process. In the first step, the thermal history is predicted from an input torque based thermal model. The temperature history generated by the thermal model is then sequentially coupled to a mechanical model that predicts the residual stresses. The model does not deal with the severe plastic deformations within the weld nugget and the thermo-mechanically affected regions, a fact that may cause modeled results to deviate from experimentally measured residual stresses. The model is three dimensional and uses temperature dependent material and thermophysical properties.

Boundary Condition Design to Heat a Moving Object at Uniform Transient Temperature Using Inverse Formulation

2004 ◽  
Vol 126 (3) ◽  
pp. 619-626 ◽  
Author(s):  
Hakan Ertu¨rk ◽  
Ofodike A. Ezekoye ◽  
John R. Howell
Keyword(s):  
Boundary Condition ◽  
Temperature Distribution ◽  
Design Problem ◽  
Manufacturing Industry ◽  
Three Dimensional ◽  
Chemical Deposition ◽  
Iterative Solution ◽  
Conveyor Belt ◽  
Temperature History ◽  
Transient Temperature

The boundary condition design of a three-dimensional furnace that heats an object moving along a conveyor belt of an assembly line is considered. A furnace of this type can be used by the manufacturing industry for applications such as industrial baking, curing of paint, annealing or manufacturing through chemical deposition. The object that is to be heated moves along the furnace as it is heated following a specified temperature history. The spatial temperature distribution on the object is kept isothermal through the whole process. The temperature distribution of the heaters of the furnace should be changed as the object moves so that the specified temperature history can be satisfied. The design problem is transient where a series of inverse problems are solved. The process furnace considered is in the shape of a rectangular tunnel where the heaters are located on the top and the design object moves along the bottom. The inverse design approach is used for the solution, which is advantageous over a traditional trial-and-error solution where an iterative solution is required for every position as the object moves. The inverse formulation of the design problem is ill-posed and involves a set of Fredholm equations of the first kind. The use of advanced solvers that are able to regularize the resulting system is essential. These include the conjugate gradient method, the truncated singular value decomposition or Tikhonov regularization, rather than an ordinary solver, like Gauss-Seidel or Gauss elimination.

scholarly journals Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

scholarly journals A new boundary element algorithm for modeling and simulation of nonlinear thermal stresses in micropolar FGA composites with temperature-dependent properties

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Mohamed Abdelsabour Fahmy
Keyword(s):  
Modeling And Simulation ◽  
Boundary Element ◽  
Thermal Stresses ◽  
Computation Time ◽  
Functionally Graded ◽  
Temperature Dependent ◽  
Time Step ◽  
Kirchhoff Transformation ◽  
Nonlinear Temperature ◽  
Temperature Dependent Properties

AbstractThe main aim of this article is to develop a new boundary element method (BEM) algorithm to model and simulate the nonlinear thermal stresses problems in micropolar functionally graded anisotropic (FGA) composites with temperature-dependent properties. Some inside points are chosen to treat the nonlinear terms and domain integrals. An integral formulation which is based on the use of Kirchhoff transformation is firstly used to simplify the transient heat conduction governing equation. Then, the residual nonlinear terms are carried out within the current formulation. The domain integrals can be effectively treated by applying the Cartesian transformation method (CTM). In the proposed BEM technique, the nonlinear temperature is computed on the boundary and some inside domain integral. Then, nonlinear displacement can be calculated at each time step. With the calculated temperature and displacement distributions, we can obtain the values of nonlinear thermal stresses. The efficiency of our proposed methodology has been improved by using the communication-avoiding versions of the Arnoldi (CA-Arnoldi) preconditioner for solving the resulting linear systems arising from the BEM to reduce the iterations number and computation time. The numerical outcomes establish the influence of temperature-dependent properties on the nonlinear temperature distribution, and investigate the effect of the functionally graded parameter on the nonlinear displacements and thermal stresses, through the micropolar FGA composites with temperature-dependent properties. These numerical outcomes also confirm the validity, precision and effectiveness of the proposed modeling and simulation methodology.

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