Second law analysis of recharging microchannel using entropy generation minimization method

The current study is an attempt to analytically characterize the second law analysis and mixed convective rheology of the (Al2O3–Ag/H2O) hybrid nanofluid flow influenced by magnetic induction effects towards a stretching sheet. Viscous dissipation and internal heat generation effects are encountered in the analysis as well. The mathematical model of partial differential equations is fabricated by employing boundary-layer approximation. The transformed system of nonlinear ordinary differential equations is solved using the homotopy analysis method. The entropy generation number is formulated in terms of fluid friction, heat transfer and Joule heating. The effects of dimensionless parameters on flow variables and entropy generation number are examined using graphs and tables. Further, the convergence of HAM solutions is examined in terms of defined physical quantities up to 20th iterations, and confirmed. It is observed that large λ1 upgrades velocity, entropy generation and heat transfer rate, and drops the temperature. High values of δ enlarge velocity and temperature while reducing heat transport and entropy generation number. Viscous dissipation strongly influences an increase in flow and heat transfer rate caused by a no-slip condition on the sheet.

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Second Law Analysis of Spray Evaporation

Journal of Energy Resources Technology ◽

10.1115/1.2905719 ◽

1990 ◽

Vol 112 (2) ◽

pp. 130-135 ◽

Cited By ~ 6

Author(s):

S. K. Som ◽

A. K. Mitra ◽

S. P. Sengupta

Keyword(s):

Heat Transfer ◽

Reynolds Number ◽

Entropy Generation ◽

Exergy Analysis ◽

Droplet Evaporation ◽

Second Law ◽

Hot Gas ◽

Second Law Analysis ◽

Initial Drop ◽

Parallel Stream

A second law analysis has been developed for an evaporative atomized spray in a uniform parallel stream of hot gas. Using a discrete droplet evaporation model, an equation for entropy balance of a drop has been formulated to determine numerically the entropy generation histories of the evaporative spray. For the exergy analysis of the process, the rate of heat transfer and that of associated irreversibilities for complete evaporation of the spray have been calculated. A second law efficiency (ηII), defined as the ratio of the total exergy transferred to the sum of the total exergy transferred and exergy destroyed, is finally evaluated for various values of pertinent input parameters, namely, the initial Reynolds number (Rei = 2ρgVixi/μg) and the ratio of ambient to initial drop temperature (Θ∞′/Θi′).

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Second-Law Analysis on Wavy Plate Fin-and-Tube Heat Exchangers

Journal of Heat Transfer ◽

10.1115/1.2824357 ◽

1998 ◽

Vol 120 (3) ◽

pp. 797-800 ◽

Cited By ~ 8

Author(s):

W. W. Lin ◽

D. J. Lee

Keyword(s):

Entropy Generation ◽

Operating Conditions ◽

Generation Rate ◽

Entropy Generation Rate ◽

Second Law ◽

Spanwise Direction ◽

Minimum Entropy ◽

Tube Heat Exchanger ◽

Second Law Analysis ◽

Minimum Entropy Generation

Second-law analysis on the herringbone wavy plate fin-and-tube heat exchanger was conducted on the basis of correlations of Nusselt number and friction factor proposed by Kim et al. (1997), from which the entropy generation rate was evaluated. Optimum Reynolds number and minimum entropy generation rate were found over different operating conditions. At a fixed heat duty, the in-line layout with a large tube spacing along streamwise direction was recommended. Furthermore, within the valid range of Kim et al.’s correlation, effects of the fin spacing and the tube spacing along spanwise direction on the second-law performance are insignificant.

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Second Law Analysis of Magneto-Micropolar Fluid Flow Between Parallel Porous Plates

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4039633 ◽

2018 ◽

Vol 10 (4) ◽

Cited By ~ 1

Author(s):

Abbas Kosarineia ◽

Sajad Sharhani

Keyword(s):

Magnetic Field ◽

Reynolds Number ◽

Fluid Flow ◽

Entropy Generation ◽

Hartmann Number ◽

Second Law ◽

Brinkman Number ◽

Viscosity Parameter ◽

Micropolar Fluid Flow ◽

Second Law Analysis

In this study, the influence of the applied magnetic field is investigated for magneto-micropolar fluid flow through an inclined channel of parallel porous plates with constant pressure gradient. The lower plate is maintained at constant temperature and the upper plate at a constant heat flux. The governing motion and energy equations are coupled while the effect of the applied magnetic field is taken into account, adding complexity to the already highly correlated set of differential equations. The governing equations are solved numerically by explicit Runge–Kutta. The velocity, microrotation, and temperature results are used to evaluate second law analysis. The effects of characteristic and dominate parameters such as Brinkman number, Hartmann Number, Reynolds number, and micropolar viscosity parameter are discussed on velocity, temperature, microrotation, entropy generation, and Bejan number in different diagrams. The results depicted that the entropy generation number rises with the increase in Brinkman number and decays with the increase in Hartmann Number, Reynolds number, and micropolar viscosity parameter. The application of the magnetic field induces resistive force acting in the opposite direction of the flow, thus causing its deceleration. Moreover, the presence of magnetic field tends to increase the contribution of fluid friction entropy generation to the overall entropy generation; in other words, the irreversibilities caused by heat transfer reduced. Therefore, to minimize entropy, Brinkman number and Hartmann Number need to be controlled.

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Optimization of microchannel heat sinks using entropy generation minimization method

Twenty-Second Annual IEEE Semiconductor Thermal Measurement And Management Symposium ◽

10.1109/stherm.2006.1625210 ◽

2006 ◽

Cited By ~ 21

Author(s):

W.A. Khan ◽

M.M. Yovanovich ◽

J.R. Culham

Keyword(s):

Entropy Generation ◽

Heat Sinks ◽

Minimization Method ◽

Entropy Generation Minimization ◽

Microchannel Heat Sinks

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Entropy Analysis of a R32/CO2 Cascade Refrigeration Cycle

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.672-674.1676 ◽

2014 ◽

Vol 672-674 ◽

pp. 1676-1679

Author(s):

Jian Xiao ◽

Ying Fu Liu

Keyword(s):

Entropy Generation ◽

Temperature Difference ◽

Design Parameters ◽

Refrigeration Cycle ◽

Total Entropy ◽

Entropy Analysis ◽

Minimization Method ◽

Entropy Generation Minimization ◽

Cascade Refrigeration

In order to study the performance of a R32/CO2 cascade refrigeration cycle, entropy generation minimization method was adopted to get the influence of some important operating and design parameters on the performance of the system and entropy generations of each component and the whole system, such as the evaporating temperature(Te), the condensing temperature(Tk) and the temperature difference in the cascade condenser(ΔT). The results indicate that there are a maximum COP and a minimum total entropy generation of the system at the optimal condensing temperature of the cascade condenser when Te, Tk and ΔT are constant. The total entropy generations of the throttling device, the condenser and the compressor of HTC, the cascade condenser and the compressor of LTC are above 80% of the total entropy generation of the whole system.

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