scholarly journals Second Law Analysis of Al2O3-Water Nanofluid Turbulent Forced Convection in a Circular Cross Section Tube with Constant Wall Temperature

2013 ◽  
Vol 5 ◽  
pp. 920278 ◽  
Author(s):  
Vincenzo Bianco ◽  
Oronzio Manca ◽  
Sergio Nardini
Keyword(s):  
Forced Convection ◽  
Cross Section ◽  
Wall Temperature ◽  
Circular Cross Section ◽  
Second Law ◽  
Constant Wall Temperature ◽  
Second Law Analysis

Second law analysis of compressible flow through a diffuser subjected to constant wall temperature

2010 ◽  
Vol 7 (1) ◽  
pp. 110
Author(s):  
Mohammad Hasan Arshad ◽  
Ramazan Kahraman ◽  
Ahmet Z. Sahin ◽  
Rached Ben Mansour
Keyword(s):  
Compressible Flow ◽  
Wall Temperature ◽  
Second Law ◽  
Constant Wall Temperature ◽  
Second Law Analysis ◽  
Flow Through

Discussion: “Second Law Analysis of Laminar Viscous Flow Through a Duct Subjected to Constant Wall Temperature” (Sahin, A. Z., 1998, ASME J. Heat Transfer, 120, pp. 76–83)

2007 ◽  
Vol 129 (9) ◽  
pp. 1302-1302 ◽  
Author(s):  
M. M. Awad
Keyword(s):  
Heat Transfer ◽  
Viscous Flow ◽  
Wall Temperature ◽  
Second Law ◽  
Constant Wall Temperature ◽  
Second Law Analysis ◽  
Flow Through

In the paper Sahin, A. Z., 1998, “Second Law Analysis of Laminar Viscous Flow Through a Duct Subjected to Constant Wall Temperature” ASME J. Heat Transfer, 120(1), pp. 76–83, there are many errors in equations, values, etc. The errors will be summarized below.

Heat Transfer Characteristics of Various Gun Barrels Under Different Operating Conditions

2019 ◽  
Author(s):  
Mohamed Gadalla ◽  
Muhammad Jasim ◽  
Omar Ahmad
Keyword(s):  
Heat Transfer ◽  
Thermal Management ◽  
Cross Section ◽  
Wall Temperature ◽  
Circular Cross Section ◽  
Typical Case ◽  
Operating Conditions ◽  
Firing Process ◽  
Transfer Model ◽  
Gun Barrel

Abstract The thermal stability parameter is an important parameter for predicting the lifespan of structures. In this paper, a two-dimensional transient heat transfer model of machine gun barrels undergoing continuous firing developed and analyzed for different geometries and thermal properties. The model for the transient thermal analysis is based on the forced convection heat transfer at the inner surface of the gun barrel. Finite element simulations were performed to predict the interior and exterior barrel temperature profiles and temperature contours after continuous firing process. The incomplete Cholesky Conjugate Gradient (ICCG) solver was adopted in solving unsymmetrical thermal transient analyses. The material thermal behavior studied for the basic circular cross section of gun barrels showed that the lowest inner wall temperature was for high rounds was achieved in steel barrels due to the rapid conducted and convective heat transfer to the environment. While the highest inner wall temperature was recorded for ceramic STK4 barrels and an increase of inner wall temperature by 17% was observed as compared to the typical case of circular cross section steel barrel. In general, a higher inner temperature in the gun barrel is undesirable and harm due to the possibility of reaching the cook-off scenario at earlier rounds. Results concluded that non-circular geometries with constrained cross section areas of typical case improve thermal management and the hexagonal geometry had the best thermal management and could provide more rounds for users. In addition, titanium barrels would have a weight drop of 41% while the overall barrel’s temperature increases by 49%.

Natural Convection Heat and Mass Transfer From a Horizontal Cylinder of Elliptic Cross Section with Constant Wall Temperature and Concentration in Saturated Porous Media

2006 ◽  
Vol 22 (3) ◽  
pp. 257-261 ◽  
Author(s):  
C.-Y. Cheng
Keyword(s):  
Mass Transfer ◽  
Natural Convection ◽  
Heat And Mass Transfer ◽  
Cross Section ◽  
Wall Temperature ◽  
Horizontal Cylinder ◽  
Elliptic Cross Section ◽  
Convection Heat ◽  
Constant Wall Temperature ◽  
Elliptic Cross

AbstractThis work studies the natural convection heat and mass transfer near a horizontal cylinder of elliptic cross section with constant wall temperature and concentration in a fluid-saturated porous medium. A coordinate transformation is used to obtain the nonsimilar governing boundary layer equations. The transformed governing equations are then solved by the cubic spline collocation method. Results for the local Nusselt and Sherwood numbers are presented as functions of the Lewis number, the buoyancy ratio, and the aspect ratio when the major axis of the elliptical cylinder is vertical (slender orientation) and horizontal (blunt orientation). The heat and mass transfer rates of the elliptical cylinder with slender orientation are higher than those with blunt orientation.

Second Law Analysis of Laminar Viscous Flow Through a Duct Subjected to Constant Wall Temperature

1998 ◽  
Vol 120 (1) ◽  
pp. 76-83 ◽  
Author(s):  
A. Z. S¸ahin
Keyword(s):  
Viscous Flow ◽  
Entropy Generation ◽  
Wall Temperature ◽  
Viscous Friction ◽  
Inlet Temperature ◽  
Total Heat Flux ◽  
Pumping Power ◽  
Constant Wall Temperature ◽  
Second Law Analysis ◽  
Flow Through

Entropy generation for a fully developed laminar viscous flow in a duct subjected to constant wall temperature is investigated analytically. The temperature dependence on the viscosity is taken into consideration in the analysis. The ratio of the pumping power to the total heat flux decreases considerably and the entropy generation increases along the duct length for viscous fluids. The variation of total exergy loss due to both the entropy generation and the pumping process is studied along the duct length as well as varying the fluid inlet temperature for fixed duct length. For low heat transfer conditions the entropy generation due to viscous friction becomes dominant and the dependence of viscosity with the temperature becomes essentially important to be considered in order to determine the entropy generation accurately.

On the Convective Heat Transfer in a Tube of Elliptic Cross Section Maintained Under Constant Wall Temperature

1986 ◽  
Vol 108 (1) ◽  
pp. 33-39 ◽  
Author(s):  
M. A. Ebadian ◽  
H. C. Topakoglu ◽  
O. A. Arnas
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Temperature Distribution ◽  
Convective Heat Transfer ◽  
Cross Section ◽  
Convective Heat ◽  
Wall Temperature ◽  
Elliptic Cross Section ◽  
Constant Wall Temperature ◽  
Elliptic Cross

The convective heat transfer problem along the portion of a tube of elliptic cross section maintained under a constant wall temperature where hydrodynamically and thermally fully developed flow conditions prevail is solved in this paper. The successive approximation method is used for the solution utilizing elliptic coordinates. Analytical expressions for temperature distribution and Nusselt number corresponding to the first cycle of approximation are obtained in terms of the ellipticity of the cross section. In the case of a circular section, the first cycle approximation of the Nusselt number is obtained as 3.7288 compared to the exact value of 3.6568. Representative temperature distribution curves are plotted and compared to those corresponding with constant wall heat flux conditions.

Second-Law Analysis of Heat Transfer in Swirling Flow Through a Cylindrical Duct

1987 ◽  
Vol 109 (2) ◽  
pp. 308-313 ◽  
Author(s):  
P. Mukherjee ◽  
G. Biswas ◽  
P. K. Nag
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Swirling Flow ◽  
Tangential Velocity ◽  
Merit Function ◽  
Second Law ◽  
Constant Wall Temperature ◽  
Boundary Layer Equations ◽  
Second Law Analysis ◽  
Cylindrical Duct

A second-law analysis is made on a swirling flow in a cylindrical duct with constant wall temperature. A purely tangential entry of the fluid is considered and a simplified model, consisting of a central air core enclosed by a potential, free vortex region and a boundary layer, is assumed. The approximate hydrodynamic boundary layer equations, and the continuity equation, are set up and solved numerically for the velocity gradients in the boundary layer. Similarly, the temperature gradients within the thermal boundary layer are obtained from the energy equation. The local Nusselt number and rate of entropy generation are calculated and used to evaluate the rate of heat transfer and loss of available energy, respectively. A merit function, defined as the ratio of exergy transferred to the sum of exergy transferred and exergy destroyed, is evaluated for various values of Reynolds number, based on the inlet tangential velocity, and conclusions are drawn about the influence of inlet swirl on irreversibility.

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