scholarly journals Studies on Behaviour of in Service Tubular Material Used at Refinery Process Furnaces

2019 ◽  
Vol 70 (4) ◽  
pp. 1162-1166
Author(s):  
Ibrahim Naim Ramadan ◽  
Eugen Victor Laudacescu ◽  
Maria Popa ◽  
Loredana Irena Negoita
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Pipe Wall ◽  
Heat Transfer Analysis ◽  
If Steel ◽  
Medium Temperature ◽  
Refinery Process ◽  
Carburizing Process ◽  
Allowable Temperature ◽  
Tubing Material

The purpose of the heat transfer analysis at the level of the technological furnace in radiation section was to determine the medium temperature on the outside wall of the pipeline through which the effluent is processed. It is important to keep an outside temperature of the wall of the duct below the maximum allowable temperature at which this carburizing process takes place. Thus, the temperature calculated on the outside pipe wall is 523.5 oC and the maximum allowable temperature of the outside pipe wall is 595.5oC. The carburizing process leads to the modification of the thermal conductivity of the tubing material. Therefore, if steel is enriched with carbon, thermal conductivity decreases.

Characterization of Tissue Thermal Conductivity During a Tissue Joining Process

2016 ◽  
Author(s):  
Che-Hao Yang ◽  
Yang Liu ◽  
Wei Li ◽  
Roland K. Chen
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Tissue Sample ◽  
Heat Transfer Analysis ◽  
Vessel Sealing ◽  
Inverse Heat Transfer ◽  
Thermal Spread ◽  
Higher Temperature ◽  
Postoperative Problems ◽  
Joining Process

Electrosurgical vessel sealing, a tissue joining process, has been widely used in surgical procedures, such as prostatectomies for bleeding control. The heat generated during the process may cause thermal damages to the surrounding tissues which can lead to detrimental postoperative problems. Having better understanding about the thermal spread helps to minimize these undesired thermal damages. The purpose of this study is to investigate the changes of tissue thermal conductivity during the joining process. We propose a hybrid method combining experimental measurement with inverse heat transfer analysis to determine thermal conductivity of thin tissue sample. Instead of self-heating the tissue by the thermistor, we apply an external cold boundary on the other side of the tissue sample to stimulate a higher temperature gradient without denaturing the tissue in comparison to the heated method. The inverse heat transfer technique was then applied to determine the tissue thermal conductivity. Tissue thermal conductivity at different levels (0%, 25%, 50%, 75%, and 100%) of the joining process was measured. The results show a decreasing trend in tissue thermal conductivity with increasing joining level. When the tissue is fully joined, an average of 60% reduction in tissue thermal conductivity was found.

Thermal Conductivity and Specific Heat Evaluation of Tissue Using Laser

2020 ◽  
Vol 1002 ◽  
pp. 303-310
Author(s):  
Sudad Issam Younis ◽  
Haqi I. Qatta ◽  
Mohammed Jalal Abdul Razzaq ◽  
Khalid S. Shibib
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Specific Heat ◽  
Iterative Procedure ◽  
Input Data ◽  
Maximum Error ◽  
Heat Transfer Analysis ◽  
Long Wavelength ◽  
Inverse Heat Transfer

In this work, an inverse heat transfer analysis was used to determine thermal conductivity and specific heat of tissue using special iteration. A laser with a long wavelength was utilized to impose heat to the tissue. The heat that induced in the sample causes an increase in the temperature of a tissue which is measured by a thermocouple. The readings were used together with that analytically obtained from the solution of the heat equation in an iterative procedure to obtain the thermal properties of tissue. By using this method, accurate thermal conductivity and specific heat of tissue could be obtained. It was found that the maximum error in output result and the error in input data were in the same order and that there was a linear relationship between output and input errors.

MHD slip flow and convective heat transfer due to a moving plate with effects of variable viscosity and thermal conductivity

2020 ◽  
Vol 16 (5) ◽  
pp. 991-1018
Author(s):  
Mahantesh M. Nandeppanavar ◽  
M.C. Kemparaju ◽  
R. Madhusudhan ◽  
S. Vaishali
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Boundary Layer ◽  
Differential Equations ◽  
Radiation Effects ◽  
Variable Viscosity ◽  
Heat Transfer Analysis ◽  
Concentration Profiles ◽  
Moving Plate ◽  
Content Type

PurposeThe steady two-dimensional laminar boundary layer flow, heat and mass transfer over a flat plate with convective surface heat flux was considered. The governing nonlinear partial differential equations were transformed into a system of nonlinear ordinary differential equations and then solved numerically by Runge–Kutta method with the most efficient shooting technique. Then, the effect of variable viscosity and variable thermal conductivity on the fluid flow with thermal radiation effects and viscous dissipation was studied. Velocity, temperature and concentration profiles respectively were plotted for various values of pertinent parameters. It was found that the momentum slip acts as a boost for enhancement of the velocity profile in the boundary layer region, whereas temperature and concentration profiles decelerate with the momentum slip.Design/methodology/approachNumerical Solution is applied to find the solution of the boundary value problem.FindingsVelocity, heat transfer analysis is done with comparing earlier results for some standard cases.Originality/value100

On the Estimation of Oxide Scale Growth in T22 Superheater and Reheater Tubes

2012 ◽  
Vol 516-517 ◽  
pp. 364-369
Author(s):  
Cai Xia Bian ◽  
Ke Yi Zhou ◽  
Jian Qun Xu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Oxide Scale ◽  
Growth Kinetics ◽  
Iterative Procedure ◽  
Heat Transfer Analysis ◽  
Oxide Growth ◽  
Scale Growth ◽  
Small Influence ◽  
Influence Degree

In this paper, an iterative procedure was performed for the prediction of scale growth in T22 superheater and reheater tubes, which utilized empirical formulae for oxide-growth kinetics in steam and heat transfer analysis. Several expressions for oxide-growth kinetics and different thermal conductivities of scale were considered in calculations. The results indicate that the expression for oxide-growth kinetics can affect the estimated results significantly, and the thermal conductivity of scale has relatively small influence on the prediction of scale growth, but the influence degree increases with time.

Convective Heat Transfer Analysis of Open Cell Metal Foam for Solar Air Heaters

Solar Energy ◽  
2003 ◽  
Author(s):  
Nihad Dukhan ◽  
Pablo D. Quinones
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Metal Foam ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Aluminum Foams ◽  
Maximum Heat ◽  
Open Cell ◽  
Maximum Heat Transfer

A one-dimensional heat transfer model for open-cell metal foam is presented. Three aluminum foams having different areas, relative densities, ligament diameters, and number of pores per inch were analyzed. The effective thermal conductivity and the heat transfer increased with the number of pores per inch. The effective thermal conductivity of the foams can be up to four times higher than that of solid aluminum. The resulting improvement in heat transfer can be as high as 50 percent. The maximum heat transfer for the aluminum foams occurs at a pore Reynolds number of 52. The heat transfer, in addition, becomes insensitive to the flow regime for pore Reynolds numbers beyond 200.

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