Journal Articles
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Item Investigation of Mixed Convection Heat Transfer Through Metal Foams Partially Filled in a Vertical Channel by Using Computational Fluid Dynamics(American Society of Mechanical Engineers (ASME) infocentral@asme.org, 2018) Kotresha, B.; Gnanasekaran, N.Two-dimensional computational fluid dynamics simulations of mixed convection heat transfer through aluminum metal foams partially filled in a vertical channel are carried out numerically. The objective of the present study is to quantify the effect of metal foam thickness on the fluid flow characteristics and the thermal performance in a partially filled vertical channel with metal foams for a fluid velocity range of 0.05-3 m/s. The numerical computations are performed for metal foam filled with 40%, 70%, and 100% by volume in the vertical channel for four different pores per inch (PPIs) of 10, 20, 30, and 45 with porosity values varying from 0.90 to 0.95. To envisage the characteristics of fluid flow and heat transfer, two different models, namely, Darcy Extended Forchheirmer (DEF) and Local thermal non-equilibrium, have been incorporated for the metal foam region. The numerical results are compared with experimental and analytical results available in the literature for the purpose of validation. The results of the parametric studies on vertical channel show that the Nusselt number increases with the increase of partial filling of metal foams. The thermal performance of the metal foams is reported in terms of Colburn j and performance factors. © Copyright 2018 by ASME.Item Comparison of fluid flow and heat transfer through metal foams and wire mesh by using CFD(Bentham Science Publishers, 2019) Kotresha, B.; Gnanasekaran, N.Background: The unique structural characteristics of the metal foams, such as low density, large surface area, ability to increase turbulence, and increased heat transfer efficiency, are the advantages associated with thermal applications such as electronics cooling, refrigeration air conditioning, etc. The porous metal foam structures are extensively used to enhance heat transfer. Objective: This paper discusses the numerical simulations of a vertical channel filled with metal foam and wire mesh. The fluid flow and heat transfer phenomena of a wire mesh are compared with two different types of metal foams. Metal foams are made of aluminium and copper while the wire mesh is made of brass. The porosity of the metallic porous structures varies from 0.85 to 0.95. Methods: A Darcy extended Forchheirmer model is considered for solving fluid flow through the porous media while the heat transfer through the porous media is predicted using local thermal non-equilibrium model. Results: Initially, the results obtained using the proposed numerical procedures are compared with experimental results available in the literature. The numerical simulations suggest that the pressure drop increases as the velocity of the fluid increases and decreases as the porosity increases. The heat transfer coefficient and Nusselt number are determined for both the metal foams and the wire mesh. Conclusion: The Nusselt number obtained for wire mesh shows almost 90% of the copper metal foam in the same porosity range. The numerical results suggest that the brass wire mesh porous medium can also be used for enhancement of heat transfer. In this article, patents have been discussed. © 2019 Bentham Science Publishers.Item Effect of thickness and thermal conductivity of metal foams filled in a vertical channel – a numerical study(Emerald Publishing, 2019) Kotresha, B.; Gnanasekaran, N.Purpose: This paper aims to discuss about the two-dimensional numerical simulations of fluid flow and heat transfer through high thermal conductivity metal foams filled in a vertical channel using the commercial software ANSYS FLUENT. Design/methodology/approach: The Darcy Extended Forchheirmer model is considered for the metal foam region to evaluate the flow characteristics and the local thermal non-equilibrium heat transfer model is considered for the heat transfer analysis; thus the resulting problem becomes conjugate heat transfer. Findings: Results obtained based on the present simulations are validated with the experimental results available in literature and the agreement was found to be good. Parametric studies reveal that the Nusselt number increases in the presence of porous medium with increasing thickness but the effect because of the change in thermal conductivity was found to be insignificant. The results of heat transfer for the metal foams filled in the vertical channel are compared with the clear channel in terms of Colburn j factor and performance factor. Practical implications: This paper serves as the current relevance in electronic cooling so as to open up more parametric and optimization studies to develop new class of materials for the enhancement of heat transfer. Originality/value: The novelty of the present study is to quantify the effect of metal foam thermal conductivity and thickness on the performance of heat transfer and hydrodynamics of the vertical channel for an inlet velocity range of 0.03-3 m/s. © 2018, Emerald Publishing Limited.Item A Synergistic Combination of Thermal Models for Optimal Temperature Distribution of Discrete Sources Through Metal Foams in a Vertical Channel(American Society of Mechanical Engineers (ASME) infocentral@asme.org, 2019) Kotresha, B.; Gnanasekaran, N.This paper discusses about the numerical prediction of forced convection heat transfer through high-porosity metal foams with discrete heat sources in a vertical channel. The physical geometry consists of a discrete heat source assembly placed at the center of the channel along with high thermal conductivity porous metal foams in order to enhance the heat transfer. The novelty of the present work is the use of combination of local thermal equilibrium (LTE) model and local thermal nonequilibrium (LTNE) model for the metal foam region to investigate the temperature distribution of the heat sources and to obtain an optimal heat distribution so as to achieve isothermal condition. Aluminum and copper metal foams of 10 PPI having a thickness of 20 mm are considered for the numerical simulations. The metal foam region is considered as homogeneous porous media and numerically modeled using Darcy Extended Forchheimer model. The proposed methodology is validated using the experimental results available in literature. The results of the present numerical solution indicate that the excess temperature of the bottom heat source reduces by 100 °C with the use of aluminum metal foam. The overall temperature of the vertical channel reduces based on the combination of LTE and LTNE models compared to only LTNE model. The results of excess temperature for both the empty and the metal foam filled vertical channels are presented in this work. © 2019 by ASME.Item Numerical Simulations of Flow-Assisted Mixed Convection in a Vertical Channel Filled with High Porosity Metal Foams(Taylor and Francis Ltd., 2020) Kotresha, B.; Gnanasekaran, N.; Balaji, C.In this work, two-dimensional numerical simulations of flow-assisted mixed convection in a vertical channel filled with high porosity metal foams have been carried out by using the commercial ANSYS FLUENT. In order to enhance heat transfer, the vertical channel is filled with aluminum metal foams of different pores per inch (PPI). Four different metal foams PPI 10, 20, 30, and 45, with porosity values varying from 0.90 to 0.95 are considered in this study. The geometry under consideration consists of metal foam attached to the aluminum plate in the vertical channel and the resulting problem becomes conjugate heat transfer. The metal foam region is considered as a homogeneous porous medium with the Darcy Extended Forchheirmer model to evaluate the flow characteristics while the local thermal non-equilibrium heat transfer model is considered for the heat transfer analysis. Initially, numerical results are compared with the experimental results available in literature and the agreement was found to be good. Parametric studies show that as the metal foam PPI increases, the pressure drop increases, while the heat transfer is seen to increase with an increase in the pore density of the metal foam. © 2019, © 2019 Taylor & Francis Group, LLC.Item Numerical Simulations of Fluid Flow and Heat Transfer through Aluminum and Copper Metal Foam Heat Exchanger–A Comparative Study(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2020) Kotresha, B.; Gnanasekaran, N.This article discusses about a numerical simulation of a metal foam heat exchanger system carried out by a commercial software. A metal foam layer is attached to the bottom of the heat exchanger to absorb heat from the exhaust hot gas leaving the system. Two types of metal foams with two different pores per inch (PPI) values are considered for heat transfer enhancement. Similarly, two different materials Aluminum and copper, that poses high thermal conductivity, metal foams are considered for the present numerical simulations. The heat exchanger system is simulated over a range of 6–30 m/s fluid velocity. The proposed simulations are compared with theoretical and experimental data available in the literature. The goal is to improve the thermal performance of the heat exchanger by decreasing the pressure drop and maximizing the heat transfer rate. Finally, it has been noticed that the velocity of the fluid decreases as PPI increases at the expense of its pressure drop. The copper metal foam gives a maximum increase of 4–10% heat transfer rate compared to aluminum metal foams for a fluid velocity of 30 m/s. © 2019, © 2019 Taylor & Francis Group, LLC.Item Nuances of fluid flow through a vertical channel in the presence of metal foam/solid block – A hydrodynamic analysis using CFD(Elsevier Ltd, 2020) Kotresha, B.; Gnanasekaran, N.A numerical study is presented in this paper to examine the fluid flow in a vertical channel partly filled with porous metallic foams. The physical model comprises of aluminum plate-heater assembly placed in the vertical channel. Heat is carried away by the working fluid air from the plates inside the vertical channel through forced convection. High thermal conductivity metal foams are attached to the heater-plate assembly in order to reduce the temperature of the aluminum plates. Thus, the study pays attention only to the characteristics of fluid flow at different positions of the vertical channel in the presence of metal foams. The present analysis considers the Forchheimer – Extended Darcy equation for the metal foam to predict the fluid flow in conjunction with the local non-thermal equilibrium model for the analysis of heat transfer through the porous metal foams. At first, the methodology applied to the present numerical analysis is validated with the existing results. Upon reaffirming the solution methodology, the results of the metal foam study are then compared with a solid block that replaces the metal foam structure inside the vertical channel. Consequently, as a novel approach, the analysis enables one to arbitrate the tradeoff between the porous metal foam and the solid block for heat transfer augmentation from the plate assembly to the air. © 2020 Elsevier LtdItem Numerical study on maximizing heat transfer and minimizing flow resistance behavior of metal foams owing to their structural properties(Elsevier Masson SAS 62 rue Camille Desmoulins Issy les Moulineaux Cedex 92442, 2021) Trilok, T.; Gnanasekaran, N.Despite many research works considering metal foams largely involving heat exchange applications, an overall comprehensive view on the performance of metal foams based on their structural properties is hitherto unaddressed in the literature. In the present work, an air forced convection-laminar flow in a vertical channel is considered in which a heated plate along with metal foam is placed at the center. The plate is subject to constant heat flux condition to assess the performance of aluminum metal foam based on their degree of inclination towards maximizing heat transfer and minimizing flow resistance behavior in a vertical channel corresponding to the combination of structural properties they possess. Heat transfer and flow phenomena pertaining to the metal foam are numerically modeled using Local Thermal Non-Equilibrium (LTNE) and Darcy–Forchheimer flow models, respectively to obtain key thermo-hydrodynamic parameters. Both the independent and the combined effects of foam structural parameters viz., porosity and pore density on Nusselt number and friction factor are discussed justifying the effects of interfacial specific surface area and interfacial heat transfer coefficient of fluid saturated foam samples. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) a multi attribute decision-making technique is applied to solve the multi objective function to determine the performance of metal foams measured on a scale of 0 to 1. Five distinct criteria are studied involving distributed weights of 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25 and 1:0 each representing amplitudes of varying importance given to maximizing heat transfer and minimizing flow resistance characteristics of metal foams. Global performance charts are obtained, featuring performance abilities of metal foam samples covering wide ranges of porosity ranging from 0.8 to 0.97 and pore densities ranging from 5PPI to 45PPI corresponding to a given criteria involving a specific weight distribution scenario. The present work provides performance characteristics of available as well as possible foam samples with an overview idea on the range of structural aspects of foam samples, where the enhanced ability of the foam to perform best in meeting the given criteria is witnessed. © 2020 Elsevier Masson SASItem Numerical consideration of LTNE and darcy extended forchheimer models for the analysis of forced convection in a horizontal pipe in the presence of metal foam(American Society of Mechanical Engineers (ASME), 2021) Jadhav, P.H.; Gnanasekaran, N.; Arumuga Perumal, D.The intent of the current research work is to emphasize the computational modeling of forced convection heat dissipation in the presence of high porosity and thermal conductivity metallic foam in a horizontal pipe for different regimes of the fluid flow for a range of Reynolds number. A two-dimensional physical domain is considered in which Darcy extended Forchheimer (DEF) model is adopted in the aluminum metallic foam to predict the features of fluid flow and local thermal nonequilibrium (LTNE) model is employed for the analysis of heat transfer in a horizontal pipe for different flow regimes. The numerical results are initially matched with experimental and analytical results for the purpose of validation. The average Nusselt number for fully filled foam is found to be higher compared to other filling rate of metallic foams and the clear pipe at the cost of pressure drop. As an important finding, it has been observed that the laminar and transition flow gives higher heat transfer enhancement ratio and thermal performance factor compared to turbulent flow. This work resembles numerous industrial applications such as solar collectors, heat exchangers, electronic cooling, and microporous heat exchangers. The novelty of the work is the selection of suitable flow and thermal models in order to clearly assimilate the flow and heat transfer in metallic foam. The presence of aluminum metal foam is highlighted for the augmentation of heat dissipation in terms of PPI and porosity. The parametric study proposed in this work surrogates the complexity and cost involved in developing an expensive experimental setup. © 2021 American Society of Mechanical Engineers (ASME). All rights reserved.Item Conjugate heat transfer study comprising the effect of thermal conductivity and irreversibility in a pipe filled with metallic foams(Springer Science and Business Media Deutschland GmbH, 2021) Jadhav, P.H.; Gnanasekaran, N.; Arumuga Perumal, D.A.A parametric study is proposed in this paper to examine heat dissipation rate and entropy generation of a forced convection in a horizontal pipe which is filled with high porous metallic foams. The study quantifies the effect of thermal conductivity and pore density on entropy generation when the pipe is fully filled with copper, aluminium and nickel metallic foams of 0.6 m length in the fluid flow direction. To predict fluid flow and heat transfer features through these metallic foams the Darcy-extended Forchheimer (DEF) flow and the local thermal non-equilibrium (LTNE) models are employed. The characteristics of laminar, transition and turbulent in the non-foam region of the pipe are captured by considering the appropriate flow models. To affirm the methodology adopted in this work, the results of the present numerical solutions are validated with the available experimental results reported in the literature. Colburn j factor and thermal performance factor are the important factors that decide the performance and efficiency of any heat exchange device. Hence, these parameters are critically evaluated and are observed to increase with increasing pore densities of the metal foams and decrease with increasing flow rates of the fluid. Furthermore, the numerical analysis is extended to obtain the results of wall temperature, Nusselt number, heat transfer enhancement ratio, frictional irreversibility and Bejan number. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.