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

2009 ◽  
Vol 223 (11) ◽  
pp. 2595-2607 ◽  
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.

Valved Heat Engine Working on Modified Atkinson Cycle

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
C. V. Ramesh
Keyword(s):  
Thermal Efficiency ◽  
Heat Engine ◽  
Engine Performance ◽  
Inertial Force ◽  
Expansion Ratio ◽  
Stirling Engine ◽  
Performance Criteria ◽  
Stirling Cycle ◽  
Heat Engines ◽  
Atkinson Cycle

There is immense scope for the development of heat engines that can directly convert solar and biochemical renewable sources of thermal energy to high-grade energy. Regenerative Stirling cycle heat engine with its performance criteria of highest thermal efficiency and high mean effective pressure is theoretically the best engine for small capacity reciprocating heat engine. However, the practical Stirling engine performance is far from the ideal. As an alternative, practical heat engines based on thermodynamic cycles (without regeneration) other than the Stirling cycle have been suggested. This paper deals with a new concept in the design of reciprocating heat engine working on modified Atkinson cycle. In the Atkinson cycle, expansion ratio being higher than compression ratio, the thermal efficiency is better than that of the standard Otto cycle. Heat engine design based on the suggested modified Atkinson cycle can be an alternative to the practical Stirling engine. In the conceptual mechanical design of the engine suggested here, apart from utilizing the principle of Atkinson cycle for achieving higher thermal efficiency, the mechanical configuration of the reciprocating engine ensures a high degree of inertial force balancing. This can result in reduced vibrations in the mountings of the power units.

scholarly journals Analytical Assessment of (Al2O3–Ag/H2O) Hybrid Nanofluid Influenced by Induced Magnetic Field for Second Law Analysis with Mixed Convection, Viscous Dissipation and Heat Generation

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 498
Author(s):  
Wasim Ullah Khan ◽  
Muhammad Awais ◽  
Nabeela Parveen ◽  
Aamir Ali ◽  
Saeed Ehsan Awan ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Viscous Dissipation ◽  
Entropy Generation ◽  
Heat Generation ◽  
Transfer Rate ◽  
Second Law ◽  
Hybrid Nanofluid ◽  
Entropy Generation Number ◽  
Generation Number ◽  
Second Law Analysis

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.

Second Law Analysis of Spray Evaporation

1990 ◽  
Vol 112 (2) ◽  
pp. 130-135 ◽  
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′).

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

1998 ◽  
Vol 120 (3) ◽  
pp. 797-800 ◽  
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.

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

2011 ◽  
Vol 31 (14-15) ◽  
pp. 2405-2413 ◽  
Author(s):  
Aung Myat ◽  
Kyaw Thu ◽  
Young-Deuk Kim ◽  
A. Chakraborty ◽  
Won Gee Chun ◽  
...  
Keyword(s):  
Entropy Generation ◽  
Second Law ◽  
Absorption Chiller ◽  
Entropy Generation Minimization ◽  
Second Law Analysis

Analysis of Throttle Opening Variation Impact on a Diesel Engine Performance Using Second Law of Thermodynamics

2009 ◽  
Author(s):  
B. B. Sahoo ◽  
U. K. Saha ◽  
N. Sahoo ◽  
P. Prusty
Keyword(s):  
Diesel Engine ◽  
Direct Injection ◽  
Fuel Efficiency ◽  
Engine Performance ◽  
Second Law Of Thermodynamics ◽  
Operating Conditions ◽  
Second Law ◽  
Engine Fuel ◽  
Availability Analysis ◽  
Second Law Analysis

The fuel efficiency of a modern diesel engine has decreased due to the recent revisions to emission standards. For an engine fuel economy, the engine speed is to be optimum for an exact throttle opening (TO) position. This work presents an analysis of throttle opening variation impact on a multi-cylinder, direct injection diesel engine with the aid of Second Law of thermodynamics. For this purpose, the engine is run for different throttle openings with several load and speed variations. At a steady engine loading condition, variation in the throttle openings has resulted in different engine speeds. The Second Law analysis, also called ‘Exergy’ analysis, is performed for these different engine speeds at their throttle positions. The Second Law analysis includes brake work, coolant heat transfer, exhaust losses, exergy efficiency, and airfuel ratio. The availability analysis is performed for 70%, 80%, and 90% loads of engine maximum power condition with 50%, 75%, and 100% TO variations. The data are recorded using a computerized engine test unit. Results indicate that the optimum engine operating conditions for 70%, 80% and 90% engine loads are 2000 rpm at 50% TO, 2300 rpm at 75% TO and 3250 rpm at 100% TO respectively.

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

2018 ◽  
Vol 10 (4) ◽  
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.

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

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.

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