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.

scholarly journals Maximum Allowable Pressure Calculation of Water Tube Boiler during Operation

2021 ◽  
Vol 2 (3) ◽  
pp. 27-33
Author(s):  
Abdlmanam Elmaryami ◽  
Mahmoud Abdelrazek Ahmida ◽  
Walid Saleh Muhammad
Keyword(s):  
Temperature Distribution ◽  
Three Dimensional ◽  
Industrial Sector ◽  
Limiting Factors ◽  
Steam Boiler ◽  
Two Dimensional ◽  
Water Tube ◽  
Steady State Temperature ◽  
Cartesian Coordinate ◽  
Tube Life

In the steam boiler industrial sector, pressure and temperature of the water tube are the two main factors that affect 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 to control the failure and explosion of the boiler.  Once the temperature distribution is known than the limiting factors that affect the water tube life such as the maximum allowable pressure 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 the water- tube is cylindrical in shape.  In axisymmetric theory, a three-dimensional cylindrical problem like a water tube can be reduced to two-dimensional by ignoring the circumferential Ө, while the 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 computerized simulation using ANSYS 10 to find out the steady-state temperature distribution of the water tube.

Axial Transport Effects on Natural Convection Inside of an Open-Ended Annulus

1991 ◽  
Vol 113 (3) ◽  
pp. 627-634 ◽  
Author(s):  
K. Vafai ◽  
J. Ettefagh
Keyword(s):  
Temperature Distribution ◽  
Flow Field ◽  
Three Dimensional ◽  
Transient Behavior ◽  
Temperature Fields ◽  
Two Dimensional ◽  
Three Dimensional Flow ◽  
Subsequent Effect ◽  
Transport Effects ◽  
Temperature And Velocity Fields

The present work centers around a numerical three-dimensional transient investigation of the effects of axial convection on flow and temperature fields inside an open-ended annulus. The transient behavior of the flow field through the formation of a three-dimensional flow field and its subsequent effect on the temperature distribution at different axial locations within the annulus were analyzed by both finite difference and finite element methods. The results show that the axial convection has a distinctly different influence on the temperature and velocity fields. It is found that in the midportion of the annulus a two-dimensional assumption with respect to the temperature distribution can lead to satisfactory results for Ra<10,000. However, such an assumption is improper with respect to the flow field. Furthermore, it is shown that generally the errors for a two-dimensional assumption in the midportion of the annulus are less at earlier times (t<50Δt) during the transient development of the flow and temperature fields.

scholarly journals Using of Parallel Coordinates in Finding Minimum Distance in Time-Space

2019 ◽  
Vol 21 (3) ◽  
pp. 3-7
Author(s):  
Olga Blazekova ◽  
Maria Vojtekova
Keyword(s):  
Coordinate System ◽  
Minimum Distance ◽  
Three Dimensional ◽  
Multidimensional Data ◽  
Fourth Dimension ◽  
Geometric Representation ◽  
Two Dimensional ◽  
Parallel Coordinates ◽  
Time Space ◽  
Cartesian Coordinate

Airspace domain may be represented by a time-space consisting of a three-dimensional Cartesian coordinate system and time as the fourth dimension. A coordinate system provides a scheme for locating points given its coordinates and vice versa. The choice of coordinate system is important, as it transforms data to geometric representation. Visualization of the three and more dimensional data on the two-dimensional drawing - computer monitor is usually done by projection, which often can restrict the amount of information presented at a time. Using the parallel coordinate system is one of possibilities to present multidimensional data. The aim of this article is to describe basics of parallel coordinate system and to investigate lines and their characteristics in time-space.

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.

Numerical Solution to a Two-Dimensional Conduction Problem Using Rectangular and Cylindrical Body-Fitted Coordinate Systems

1981 ◽  
Vol 103 (4) ◽  
pp. 753-758 ◽  
Author(s):  
A. Goldman ◽  
Y. C. Kao
Keyword(s):  
Temperature Distribution ◽  
Coordinate System ◽  
Numerical Solution ◽  
Rectangular Plate ◽  
Three Dimensional ◽  
Cylindrical Body ◽  
Two Dimensional ◽  
Coordinate Systems

The temperature distribution in a rectangular plate with a circular void at the center was calculated using a body-fitted coordinate system. Three different transformed geometries were considered: rectangular-rectangular, cut-line, and cylindrical. Problems involving insulated outer surfaces could not be solved using the rectangular-rectangular transformation but could be solved with both the cut-line and cylindrical transformations. The cylindrical transformation also appears to have the capability of being extended to three-dimensional problems.

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.

Thermal stress analysis of the parting plane flange joint of an industrial steam turbine

1993 ◽  
Vol 28 (3) ◽  
pp. 175-180 ◽  
Author(s):  
R S Alwar ◽  
S Srinivasarao
Keyword(s):  
Steam Turbine ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Correction Factors ◽  
Design Work ◽  
Contact Behaviour ◽  
Analytical Formulae ◽  
Turbine Casing ◽  
Transient Thermal

A typical 14 MW steam turbine casing is analysed using a range of flange parameters and heating conditions with three-dimensional and two-dimensional models, in order to find the contact pressures and thermal stresses during transient thermal operations. Thermal stresses are also calculated with simple analytical formulae which are available in literature. Two-dimensional and analytical results are compared with three-dimensional results, and some correction factors are suggested. These correction factors can be used in day to day design work to obtain quick and simple solutions. Contact behaviour of the parting plane flange under transient thermal loads is studied using ‘gap’ elements available in the application software ‘NISA’.

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.

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.

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