Faculty Publications
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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 Determination of interfacial heat transfer coefficient for the flow assisted mixed convection through brass wire mesh(Elsevier Masson SAS 62 rue Camille Desmoulins Issy les Moulineaux Cedex 92442, 2019) Kotresha, B.; Gnanasekaran, N.In this work, a numerical investigation of Darcy?Forchheimer mixed convection from a heated vertical flat plate embedded in a brass wire mesh porous medium is carried out to determine the coupled effects of flow and thermal diffusion. The numerical model consists of a two dimensional computational domain in which conjugate heat transfer analysis is performed to predict the hydrodynamic and thermal performance of the brass wire mesh in a vertical channel using Local Thermal Non-Equillibrium (LTNE) model. The novelty of the present study is to acquire the interfacial heat transfer coefficient, an as yet another challenging task, of the wire mesh porous medium so as to provide a quick and feasible solution to modeling of fluid flow and heat transfer through brass wire mesh porous media. The results of heat transfer through brass wire mesh are reported in terms of Colburn j factor, performance factor and are compared with other porous mediums available in literature. The present study not only opens up new vistas for more parametric studies but also provides practical and cost effective assessment to design new porous materials. © 2018 Elsevier Masson SASItem 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 A Parametric Study on Mixed Convection in a Vertical Channel in the Presence of Wire Mesh(Taylor and Francis Ltd., 2021) Kotresha, B.; Gnanasekaran, N.A numerical study on mixed convection is carried out through a partially filled brass wire mesh in a vertical channel. A heater embedded with aluminum plates is placed at the center of the vertical channel. The aluminum heater assembly is wrapped with brass wire mesh to facilitate more heat transfer. The vertical channel that consists of aluminum heater assembly with the brass wire mesh is considered as the numerical model. Local thermal non-equilibrium and Darcy extended Forchheimer models are used to accomplish the numerical simulations for thermal and flow characteristics of the considered domain. The aim of the study is to find out the optimum filling of the brass wire mesh in the channel which gives a higher heat transfer rate with low pumping power of the fluid. In the present analysis, three different filling conditions of wire mesh are considered: (i) fully filled channel, (ii) 70% filled channel, and (iii) 40% filled channel. From the results, it is inferred that the vertical channel partially filled with 70% of wire mesh porous medium predicts 89% of heat transfer of the completely filled channel with 41% reduced pressure loss. As a result, the proposed parametric study is good enough to prove that the partly filled wire mesh can be used in the thermal applications where augmentation of heat transfer is required with less pressure drop. © 2020 Taylor & Francis Group, LLC.