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Thermodynamic optimisation of diesel engine turbocharging system. Part II

Krzysztof Nakonieczny Tadeusz R. Fodemski
Archive of Mechanical Engineering | 2002 | vol. 49 | No 3 | 201-213
Keywords turbocharging
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Abstract

The authors present the optimisation procedure and results, applied to the system discussed in part I. This procedure utilises a "fixed variables" method from the group of "search methods". The optimisation is related to the specific turbocharged engine STAR T3 70 for which necessary construction data and experimental measurements were available. Calculation results, however, are based mainly on the computer simulation of time dependant flows in the inlet and exhaust systems of this engine. They show that the presented method, after necessary improvements and the use of more advanced optimisation procedures, could represent an additional and attractive tool, which might be used by designers of such systems.
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Authors and Affiliations

Krzysztof Nakonieczny
Tadeusz R. Fodemski

Entropy generation in a condenser and related correlations

Rafał Laskowski Maciej Jaworski Adam Smyk
Archives of Thermodynamics | 2015 | No 2 June | 27-48 | DOI: 10.1515/aoter-2015-0013
Keywords steam condenser entropy generation
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Abstract

The paper presents an analysis of relations describing entropy generation in a condenser of a steam unit. Connections between entropy generation, condenser ratio, and heat exchanger effectiveness, as well as relations implied by them are shown. Theoretical considerations allowed to determine limits of individual parameters which describe the condenser operation. Various relations for average temperature of the cold fluid were compared. All the proposed relations were verified against data obtained using a simulator and actual measurement data from a 200 MW unit condenser. Based on data from a simulator it was examined how the sum of entropy rates, steam condenser effectiveness, terminal temperature difference and condenser ratio vary with the change in the inlet cooling water temperature, mass flow rate of steam and the cooling water mass flow rate.
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Authors and Affiliations

Rafał Laskowski
Maciej Jaworski
Adam Smyk

Entropy generation and thermodynamic analysis of solar air heaters with artificial roughness on absorber plate

Radha K. Prasad Mukesh K. Sahu
Archives of Thermodynamics | 2017 | No 3 | 23-48 | DOI: 10.1515/aoter-2017-0014
Keywords entropy generation analysis entropy generation number irreversibility Bejan number
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Abstract

This paper presents mathematical modelling and numerical analysis to evaluate entropy generation analysis (EGA) by considering pressure drop and second law efficiency based on thermodynamics for forced convection heat transfer in rectangular duct of a solar air heater with wire as artificial roughness in the form of arc shape geometry on the absorber plate. The investigation includes evaluations of entropy generation, entropy generation number, Bejan number and irreversibilities of roughened as well as smooth absorber plate solar air heaters to compare the relative performances. Furthermore, effects of various roughness parameters and operating parameters on entropy generation have also been investigated. Entropy generation and irreversibilities (exergy destroyed) has its minimum value at relative roughness height of 0.0422 and relative angle of attack of 0.33, which leads to the maximum exergetic efficiency. Entropy generation and exergy based analyses can be adopted for the evaluation of the overall performance of solar air heaters.

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Authors and Affiliations

Radha K. Prasad
Mukesh K. Sahu

Second law optimization and parametric study of a solar air heater having artificially roughened absorber plate

Mukesh Kumar Sahu Radha Krishna Prasad
Archives of Thermodynamics | 2019 | vol. 40 | No 2 | 107-135 | DOI: 10.24425/ather.2019.129544
Keywords Artificial roughness Entropy generation Entropy generation minimization Augmentation entropy generation number Solar air heater
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Abstract

The Bulletin of the Polish Academy of Sciences: Technical Sciences (Bull.Pol. Ac.: Tech.) is published bimonthly by the Division IV Engineering Sciences of the Polish Academy of Sciences, since the beginning of the existence of the PAS in 1952. The journal is peer‐reviewed and is published both in printed and electronic form. It is established for the publication of original high quality papers from multidisciplinary Engineering sciences with the following topics preferred: Artificial and Computational Intelligence, Biomedical Engineering and Biotechnology, Civil Engineering, Control, Informatics and Robotics, Electronics, Telecommunication and Optoelectronics, Mechanical and Aeronautical Engineering, Thermodynamics, Material Science and Nanotechnology, Power Systems and Power Electronics.

Journal Metrics: JCR Impact Factor 2018: 1.361, 5 Year Impact Factor: 1.323, SCImago Journal Rank (SJR) 2017: 0.319, Source Normalized Impact per Paper (SNIP) 2017: 1.005, CiteScore 2017: 1.27, The Polish Ministry of Science and Higher Education 2017: 25 points.

Abbreviations/Acronym: Journal citation: Bull. Pol. Ac.: Tech., ISO: Bull. Pol. Acad. Sci.-Tech. Sci., JCR Abbrev: B POL ACAD SCI-TECH Acronym in the Editorial System: BPASTS.

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Authors and Affiliations

Mukesh Kumar Sahu
Radha Krishna Prasad

Estimation of a tube diameter in a ‘church window’ condenser based on entropy generation minimization

Artur Rusowicz Rafał Laskowski Andrzej Grzebielec
Archives of Thermodynamics | 2015 | No 3 September | 49-59 | DOI: 10.1515/aoter-2015-0021
Keywords entropy generation minimization power plant condenser tube diameter
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Abstract

The internal diameter of a tube in a ‘church window’ condenser was estimated using an entropy generation minimization approach. The adopted model took into account the entropy generation due to heat transfer and flow resistance from the cooling-water side. Calculations were performed considering two equations for the flow resistance coefficient for four different roughness values of a condenser tube. Following the analysis, the internal diameter of the tube was obtained in the range of 17.5 mm to 20 mm (the current internal diameter of the condenser tube is 22 mm). The calculated diameter depends on and is positively related to the roughness assumed in the model.
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Authors and Affiliations

Artur Rusowicz
Rafał Laskowski
Andrzej Grzebielec

Thermal and hydraulic phenomena in boundary layer of minijets impingement on curved surfaces

Tomasz Kura Elżbieta Fornalik-Wajs Jan Wajs
Archives of Thermodynamics | 2018 | vol. 39 | No 1 | DOI: 10.1515/aoter-2018-0008
Keywords Jet impingement Minijets array Boundary layer Entropy generation Nusselt number
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Abstract

Presented work considers flow and thermal phenomena occurring during the single minijet impingement on curved surfaces, heated with a constant heat flux, as well as the array of minijets. Numerical analyses, based on the mass, momentum and energy conservation laws, were conducted, regarding single phase and two-phase simulations. Focus was placed on the proper model construction, in which turbulence and boundary layer modeling was crucial. Calculations were done for various inlet parameters. Initial single minijet results served as the basis for the main calculations, which were conducted for two jet arrays, with flat and curved heated surfaces. Such complex geometries came from the cooling systems of electrical devices, and the geometry of cylindrical heat exchanger. The results, regarding Nusselt number, heated surface temperature, turbulence kinetic energy, production of entropy and vorticity, were presented and discussed. For assumed geometrical parameters similar results were obtained.

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Authors and Affiliations

Tomasz Kura
Elżbieta Fornalik-Wajs
Jan Wajs

Thermodynamic optimisation of diesel-engine turbocharging system. Part I

Krzysztof Nakonieczny Tadeusz R. Fodemski
Archive of Mechanical Engineering | 2002 | vol. 49 | No 2 | 127-140
Keywords turbocharging minimum entropy generation exergy optimisation
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Abstract

The authors present an optirrusanon method, based on the thermodynamic consideration and applied to the inlet and exhaust systems of turbocharged engine. The goal function in this method is defined as a sum of exergy irreversible losses - occurring in the whole flow path. The decision variables, optimisation parameters and, also, the constraint conditions in the discussed method are defined and determined. The validation results of specially written and unique programmes, used for flow simulations in the analysed systems, are also presented. The optimisation results, based on the discussed method and related to a specific turbocharged engine are discussed in part II.
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Authors and Affiliations

Krzysztof Nakonieczny
Tadeusz R. Fodemski

Statistical analysis of entropy generation in longitudinally finned tube heat exchanger with shell side nanofluid by a single phase approach

Pavan Kumar Konchada Vinay Pv Varaprasad Bhemuni
Archives of Thermodynamics | 2016 | No 2 | 3-22 | DOI: 10.1515/aoter-2016-0010
Keywords longitudinal finned tube heat exchanger user functions and CEL Expressions ANSYS CFX Taguchi entropy generation
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Abstract

The presence of nanoparticles in heat exchangers ascertained increment in heat transfer. The present work focuses on heat transfer in a longitudinal finned tube heat exchanger. Experimentation is done on longitudinal finned tube heat exchanger with pure water as working fluid and the outcome is compared numerically using computational fluid dynamics (CFD) package based on finite volume method for different flow rates. Further 0.8% volume fraction of aluminum oxide (Al2O3) nanofluid is considered on shell side. The simulated nanofluid analysis has been carried out using single phase approach in CFD by updating the user-defined functions and expressions with thermophysical properties of the selected nanofluid. These results are thereafter compared against the results obtained for pure water as shell side fluid. Entropy generated due to heat transfer and fluid flow is calculated for the nanofluid. Analysis of entropy generation is carried out using the Taguchi technique. Analysis of variance (ANOVA) results show that the inlet temperature on shell side has more pronounced effect on entropy generation.

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Authors and Affiliations

Pavan Kumar Konchada
Vinay Pv
Varaprasad Bhemuni

Entropy generation and squeezing flow past a Riga plate with Cattaneo-Christov heat flux

M. Atlas S. Hussain M. Sagheer
Bulletin of the Polish Academy of Sciences Technical Sciences | 2018 | 66 | No 3 | 291-300
Keywords squeezing flow Riga plate nanofluids convective boundary conditions Cattaneo-Christov heat flux entropy generation
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Authors and Affiliations

M. Atlas
S. Hussain
M. Sagheer

Entropy analysis of third-grade MHD convection flows from a horizontal cylinder with slip

K. Madhavi V. Ramachandra Prasad S. Abdul Gaffar K. Venkatadri
Archive of Mechanical Engineering | 2018 | vol. 65 | No 3 | 417-440
Keywords third-grade viscoelastic fluid model thermal jump entropy generation Bejan number Hartmann number
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Abstract

In thermos fluid dynamics, free convection flows external to different geometries, such as cylinders, ellipses, spheres, curved walls, wavy plates, cones, etc., play major role in various industrial and process engineering systems. The thermal buoyancy force associated with natural convection flows can play a critical role in determining skin friction and heat transfer rates at the boundary. In thermal engineering, natural convection flows from cylindrical bodies has gained exceptional interest. In this article, we mathematically evaluate an entropy analysis of magnetohydrodynamic third-grade convection flows from permeable cylinder considering velocity and thermal slip effects. The resulting non-linear coupled partial differential conservation equations with associated boundary conditions are solved with an efficient unconditionally stable implicit finite difference Keller-Box technique. The impacts of momentum and heat transport coefficients, entropy generation and Bejan number are computed for several values of non-dimensional parameters arising in the flow equations. Streamlines are plotted to analyze the heat transport process in a two-dimensional domain. Furthermore, the deviations of the flow variables are compared with those computed for a Newtonian fluid and this has important implications in industrial thermal material processing operations, aviation technology, different enterprises, energy systems and thermal enhancement of industrial flow processes.
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Authors and Affiliations

K. Madhavi
V. Ramachandra Prasad
S. Abdul Gaffar
K. Venkatadri

Numerical analysis of structure, stability and entropy generation in biogas coflow diffusion flames

R. Nivethana Kumar S. Muthu Kumaran Vasudevan Raghavan
Archive of Mechanical Engineering | 2022 | vol. 69 | No 1 | 99-128 | DOI: 10.24425/ame.2021.139648
Keywords biogas flame stability entropy generation coflow air hydrogen injection preheated reactants
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Abstract

Biogas is a gaseous biofuel predominantly composed of methane and carbon-dioxide. Stability of biogas flames strongly depend upon the amount of carbon-dioxide present in biogas, which varies with the source of biomass and reactor. In this paper, a comprehensive study on the stability and flame characteristics of coflow biogas diffusion flames is reported. Numerical simulations are carried out using reactive flow module in OpenFOAM, incorporated with variable thermophysical properties, Fick’s and Soret diffusion, and short chemical kinetics mechanism. Effects of carbon-dioxide content in the biogas, temperatures of the fuel or coflowing air streams (preheated reactant) and hydrogen addition to fuel or air streams are analyzed. Entropy generation in these flames is also predicted. Results show that the flame temperature increases with the degree of preheat of reactants and the flames show better stability with the preheated air stream. Preheating the air contributes to increased flame stability and also to a significant decrease in entropy generation. Hydrogen addition, contributing to the same power rating, is seen to be relatively more effective in increasing the flame stability when added to the fuel stream. Results in terms of flow, temperature, species and entropy fields, are used to describe the stability and flame characteristics.
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Authors and Affiliations

R. Nivethana Kumar
1
S. Muthu Kumaran
1
Vasudevan Raghavan
1
  1. Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai – 600036, India

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