A second law analysis and entropy generation minimization of an absorption chiller

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.

Download Full-text

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′).

Download Full-text

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.

Download Full-text

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.

Download Full-text

First and second law analysis of a Stirling engine with imperfect regeneration and dead volume

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/09544062jmes1651 ◽

2009 ◽

Vol 223 (11) ◽

pp. 2595-2607 ◽

Cited By ~ 6

Author(s):

J Harrod ◽

P J Mago ◽

K Srinivasan ◽

L M Chamra

Keyword(s):

Entropy Generation ◽

Thermal Efficiency ◽

Engine Performance ◽

Stirling Engine ◽

Dead Volume ◽

Second Law ◽

Work Output ◽

Volume Percentage ◽

Stirling Cycle ◽

Second Law Analysis

This article discusses the thermodynamic performance of an ideal Stirling cycle engine. This investigation uses the first law of thermodynamics to obtain trends of total heat addition, net work output, and thermal efficiency with varying dead volume percentage and regenerator effectiveness. Second law analysis is used to obtain trends for the total entropy generation of the cycle. In addition, the entropy generation of each component contributing to the Stirling cycle processes is considered. In particular, parametric studies of dead volume effects and regenerator effectiveness on Stirling engine performance are investigated. Finally, the thermodynamic availability of the system is assessed to determine theoretical second law efficiencies based on the useful exergy output of the cycle. Results indicate that a Stirling engine has high net work output and thermal efficiency for low dead volume percentages and high regenerator effectiveness. For example, compared to an engine with zero dead volume and perfect regeneration, an engine with 40 per cent dead volume and a regenerator effectiveness of 0.8 is shown to have ∼60 per cent less net work output and a 70 per cent smaller thermal efficiency. Additionally, this engine results in approximately nine times greater overall entropy generation and 55 per cent smaller second law efficiency.

Download Full-text

Second Law Analysis of Fully Developed Convection in a Helical Coiled Tube Under Constant Wall Temperature Using a CFD-ANN Approach

ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, Volume 2 ◽

10.1115/esda2010-24402 ◽

2010 ◽

Author(s):

Mostafa Emami ◽

Mohammad H. Rahimian ◽

Saeed Alem Varzane Esfehani

Keyword(s):

Reynolds Number ◽

Entropy Generation ◽

Wall Temperature ◽

Classical Method ◽

Second Law ◽

Minor Effect ◽

Optimization Approach ◽

Constant Wall Temperature ◽

Coiled Tube ◽

Entropy Generation Minimization

The present paper analyses the second law of thermodynamics in a fully developed forced convection in the horizontal helical coiled tube under constant wall temperature. The influence of non-dimensional parameters such as Reynolds number (Re), coil-to-tube ratio (δ) and coil pitch (λ) are inspected on the entropy generation. According to the literature, the coil pitch has a minor effect on the entropy generation compared with Re and δ. Using a CFD tool is a common classical method to find the optimal Reynolds Number and coil-to-tube ratio (δ) based on the entropy generation minimization principal. This approach requires lots of time and resources while the innovative implementation of an Artificial Neural Network (ANN) reduces the simulation time considerably. The data pool generated by the CFD tool is used to train the ANN. As less data is needed to train the ANN in comparison to classical CFD based method, the performance of ANN-CFD optimization approach enhances. As entropy generation minimization principal is applied during the optimization, Nusselt number and friction factor are required to evaluate the entropy generation; these parameters are obtained through a numerical simulation and then are used to train the ANN. The ANN can predict these parameters as a function of different Re numbers and coil-to-tube ratios during optimization. Several different architectures of ANNs were evaluated and parametric studies were performed to optimize network design for the best prediction of the variables. The results obtained from the ANN are compared with the available experimental data to show the network reasonable accuracy.

Download Full-text

Analytical Treatment for the Dynamics of Second Law Analysis of Jeffery Nanofluid with Convective Heat and Mass Conditions

Journal of Nanoelectronics and Optoelectronics ◽

10.1166/jno.2021.2909 ◽

2021 ◽

Vol 16 (1) ◽

pp. 89-96

Author(s):

Rizwan Akhtar ◽

Muhammad Awais ◽

Muhammad Asif Zahoor Raja ◽

M. N. Abrar ◽

Sayyar Ali Shah ◽

...

Keyword(s):

Viscous Dissipation ◽

Newtonian Fluid ◽

Entropy Generation ◽

Fluid Model ◽

Second Law ◽

Jeffrey Fluid ◽

Stretching Surface ◽

Nanofluid Flow ◽

Second Law Analysis ◽

Jeffery Nanofluid

This study has been managed for the investigation of entropy generation of inclined magnetic field (MG) on the Jeffery nanofluid flow on a stretching surface containing viscous dissipation. Heat generation or absorption effects are likewise considered on the magnetohydromagnetic flow problem and electric field is considered negligible. The boundary layer approach is incorporated for simplification of the proposed governing equations in which the target of analysis is focused near the surface of the fluidic problem. The concept of dimensionless parameters are used for simplification of the proposed system which overcomes the complexity of the problem. The relaxation and retardation times are also considered for the non-Newtonian Jeffrey fluid model for better analysis of the entropy generation of inclined MG on the Jeffery nanofluid flow on a stretching surface containing viscous dissipation. The strength of analytical homotopy analysis approach is employed for finding the solutions of the proposed fluidic system in terms of energy, momentum and concentration which is effective in the spatial domain. Graphical explanation for flow parameters have been incorporated. The tabular description is given for the convergence analysis and comparison of velocity gradient at the sheet surface f″ (0) for analytical solution (HAM) computed in this manuscript along with the numerical solution. The aim of second law analysis can be achieved by increasing the magnitude of the finite different temperature parameter. The current study is also described for Newtonian fluid as a special case of our study. Stream lines patterns are also provided for both Newtonian and non-Newtonian fluid models.

Download Full-text

Solar cooling with the absorption principle: first and Second Law analysis of an ammonia—water double-generator absorption chiller

Desalination ◽

10.1016/j.desal.2004.06.179 ◽

2004 ◽

Vol 168 ◽

pp. 137-144 ◽

Cited By ~ 24

Author(s):

N. Ben Ezzine ◽

M. Barhoumi ◽

Kh. Mejbri ◽

S. Chemkhi ◽

A. Bellagi

Keyword(s):

Second Law ◽

Absorption Chiller ◽

Ammonia Water ◽

Solar Cooling ◽

Second Law Analysis

Download Full-text

Second Law Analysis Through a Porous Poiseuille–Benard Channel Flow

Journal of Heat Transfer ◽

10.1115/1.4031731 ◽

2015 ◽

Vol 138 (2) ◽

Cited By ~ 1

Author(s):

Amel Tayari ◽

Nejib Hidouri ◽

Mourad Magherbi ◽

Ammar Ben Brahim

Keyword(s):

Heat Transfer ◽

Finite Element Method ◽

Channel Flow ◽

Entropy Generation ◽

Control Volume ◽

Second Law ◽

Brinkman Model ◽

Second Law Analysis ◽

Medium Porosity ◽

Control Volume Finite Element

This paper proposes a numerical analysis of entropy generation during mixed convection inside a porous Poiseuille–Benard channel flow, where the Darcy–Brinkman model is used. Irreversibilities due to heat transfer and viscous dissipation have been derived, and then calculated by numerically solving mass, momentum, and energy conservation equations, by using a control volume finite element method (CVFEM). For a fixed value of the thermal Rayleigh (Ra = 104) and the modified Brinkman (Br* = 10−3) numbers, transient entropy generation exhibits a periodic behavior for the medium porosity ε ≥ 0.2, which is described by the onset of thermoconvective cells inside the porous channel. Highest irreversibility is obtained at ε = 0.5. More details about the effects of the Darcy, the Rayleigh, and the modified Brinkman numbers on entropy generation and heat transfer are discussed and graphically presented.

Download Full-text