Thermal stress analysis and entropy generation rate due to laser short pulse heating of a metallic surface

2014 ◽  
Vol 92 (12) ◽  
pp. 1681-1687 ◽  
Author(s):  
Bekir Sami Yilbas ◽  
Haider Ali ◽  
Ahmad Yousef Al-Dweik
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Stress Field ◽  
Entropy Generation ◽  
Pulse Heating ◽  
Short Pulse ◽  
Entropy Generation Rate ◽  
Metallic Surface ◽  
Thermodynamic Irreversibility ◽  
Thermal Stress Field

An analytical solution is developed for thermal stress in exponentially time decaying laser short-pulse heating of a metallic surface. Because the heating duration is short, a nonequilibrium heating model incorporating the electron kinetic theory approach is used to formulate the temperature distribution during the laser heating pulse. Thermomechanical coupling is introduced in the analysis to formulate the thermal stress field. Thermodynamic irreversibility is considered and the entropy generation rate due to heat transfer and thermal stress field is formulated during the heating process. It is found that temperature decays gradually in the surface region and becomes sharp as the distance increases towards the solid bulk. Thermal stress is compressive in the irradiated region. Thermodynamic irreversibility due to heat transfer dominates thermodynamic irreversibility because of the thermal stress field.

Non-equilibrium energy transport and entropy production due to laser short-pulse irradiation

2016 ◽  
Vol 94 (1) ◽  
pp. 130-138 ◽  
Author(s):  
H. Ali ◽  
B.S. Yilbas ◽  
A.Y. Al-Dweik
Keyword(s):  
Laser Pulse ◽  
Entropy Generation ◽  
Energy Transport ◽  
Pulse Heating ◽  
Short Pulse ◽  
Generation Rate ◽  
Entropy Generation Rate ◽  
Pulse Intensity ◽  
Laser Pulse Intensity ◽  
Nano Size

Laser short-pulse heating of a nano-size wire is considered and entropy generation rate is predicted during the heating pulse. The analytical solution of the heat equation is obtained using the Lie point symmetry for the laser short-pulse heating. The nano-size wire is assumed to be symmetric along its y-axis. Laser pulse intensity is considered to be Gaussian at the irradiated surface while the exponential decay of the laser pulse is incorporated in the time domain. It is found that surface temperature variation in the lattice subsystem almost follows the laser pulse intensity distribution at the surface. Entropy generation rate attains low values along the symmetry axis and it increases considerably in the region of the nano-size wire edges. This behavior is associated with the temperature gradient, which attains high values in the region close to the nano-size wire edge.

Optimization of Radial Convective Radiating Fin Geometry for Single Cylinder Internal Combustion Engine (ICE): Entropy Generation Minimization

2005 ◽  
Author(s):  
B. N. Taufiq ◽  
T. M. I. Mahlia ◽  
H. H. Masjuki ◽  
M. S. Faizul ◽  
E. Niza Mohamad
Keyword(s):  
Heat Transfer ◽  
Entropy Generation ◽  
Combustion Engine ◽  
Fluid Velocity ◽  
Cross Flow ◽  
Entropy Generation Rate ◽  
Material Surface ◽  
Optimal Geometry ◽  
Entropy Generation Minimization ◽  
Thermodynamic Irreversibility

This study attempts to calculate the optimal geometry of convective-radiating radial of ICEs fin arrays using entropy generation method. The analysis is conducted to achieve the balance between entropy generation due to heat transfer and entropy generation due to fluid friction. In designing of the thermal system, it is important to minimize thermal irreversibilities, because the optimal geometry found while the entropy generation rate is minimized. In this study, the entropy generation minimization (EGM) technique based on fin thickness is applied to study the thermodynamic irreversibility caused by heat transfer and fluid irreversibility in radiating convective radial fin arrays. In addition, the cost parameters of fin optimum thickness is also considered and presented. The entropy generation is found to be strongly influenced by emissivity of fin material surface and increasing the cross flow fluid velocity will enhance the heat transfer rate that will reduce the heat transfer irreversibility.

Entropy generation and heat transfer analysis for ferrofluid flow between two rotating disks with variable conductivity

2021 ◽  
pp. 095440622199118
Author(s):  
Anupam Bhandari
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Differential Equations ◽  
Entropy Generation ◽  
Heat Transfer Analysis ◽  
Entropy Generation Rate ◽  
Geometrical Parameters ◽  
Rotating Disks ◽  
Coupled Differential Equations ◽  
Lower Disk

Present model analyze the flow and heat transfer of water-based carbon nanotubes (CNTs) [Formula: see text] ferrofluid flow between two radially stretchable rotating disks in the presence of a uniform magnetic field. A study for entropy generation analysis is carried out to measure the irreversibility of the system. Using similarity transformation, the governing equations in the model are transformed into a set of nonlinear coupled differential equations in non-dimensional form. The nonlinear coupled differential equations are solved numerically through the finite element method. Variable viscosity, variable thermal conductivity, thermal radiation, and volume concentration have a crucial role in heat transfer enhancement. The results for the entropy generation rate, velocity distributions, and temperature distribution are graphically presented in the presence of physical and geometrical parameters of the flow. Increasing the values of ferromagnetic interaction number, Reynolds number, and temperature-dependent viscosity enhances the skin friction coefficients on the surface and wall of the lower disk. The local heat transfer rate near the lower disk is reduced in the presence of Harman number, Reynolds number, and Prandtl number. The ferrohydrodynamic flow between two rotating disks might be useful to optimize the use of hybrid nanofluid for liquid seals in rotating machinery.

MHD and nonlinear thermal radiation effects on hybrid nanofluid past a wedge with heat source and entropy generation

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fazle Mabood ◽  
Anum Shafiq ◽  
Waqar Ahmed Khan ◽  
Irfan Anjum Badruddin
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Heat Source ◽  
Thermal Radiation ◽  
Entropy Generation ◽  
Entropy Generation Rate ◽  
Design Parameters ◽  
Hybrid Nanofluid ◽  
Nonlinear Thermal Radiation ◽  
Content Type

Purpose This study aims to investigate the irreversibility associated with the Fe3O4–Co/kerosene hybrid-nanofluid past a wedge with nonlinear radiation and heat source. Design/methodology/approach This study reports the numerical analysis of the hybrid nanofluid model under the implications of the heat source and magnetic field over a static and moving wedge with slips. The second law of thermodynamics is applied with nonlinear thermal radiation. The system that comprises differential equations of partial derivatives is remodeled into the system of differential equations via similarity transformations and then solved through the Runge–Kutta–Fehlberg with shooting technique. The physical parameters, which emerges from the derived system, are discussed in graphical formats. Excellent proficiency in the numerical process is analyzed by comparing the results with available literature in limiting scenarios. Findings The significant outcomes of the current investigation are that the velocity field uplifts for higher velocity slip and magnetic strength. Further, the heat transfer rate is reduced with the incremental values of the Eckert number, while it uplifts with thermal slip and radiation parameters. An increase in Brinkmann’s number uplifts the entropy generation rate, while that peters out the Bejan number. The results of this study are of importance involving in the assessment of the effect of some important design parameters on heat transfer and, consequently, on the optimization of industrial processes. Originality/value This study is original work that reports the hybrid nanofluid model of Fe3O4–Co/kerosene.

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