The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Radha Krishna Prasad - One of the best experts on this subject based on the ideXlab platform.
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investigation of thermal performance of unidirectional flow Porous Bed solar air heater using mlp grnn and rbf models of ann technique
Thermal science and engineering, 2018Co-Authors: Harish Kumar Ghritlahre, Radha Krishna PrasadAbstract:Abstract In the present work, Multi-layer perceptron (MLP), Generalized regression neural network (GRNN), Radial basis function (RBF) and Multiple linear regression (MLR) models has been used to predict the thermal performance of unidirectional flow Porous Bed solar air heater. These four models have been constructed on the basis of actual experimental data and calculated values. Total 96 experimental data sets have been used in the present work. In GRNN, RBF and MLP models, six input parameters such as mass flow rate, wind speed, atmospheric temperature, inlet fluid temperature, fluid mean temperature and solar intensity were used in input layer, and one variable, the thermal efficiency was used in output layer. Same parameters were used in MLR model. It is observed that GRNN model is the best model due to lowest error and highest value of R2 as compared to MLP, RBF and MLR model performances. It is found that the value of MAE, RMSE and R2 for GRNN model are 1.1128E−03, 5.9284E−06 and 0.99758 respectively, and the model efficiency is 0.99760, which is the highest value as compared to other model. These results confirmed that the GRNN model is appropriate model to predict the thermal performance of solar air heater.
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prediction of thermal performance of unidirectional flow Porous Bed solar air heater with optimal training function using artificial neural network
Energy Procedia, 2017Co-Authors: Harish Kumar Ghritlahre, Radha Krishna PrasadAbstract:Abstract In the present work, Artificial Neural Network (ANN) has been used to predict the thermal performance of unidirectional flow Porous Bed solar air heater. The ANN model was structured on the basis of data sets obtained from experiments and values of thermal efficiency of solar air heater. Four types of training functions are used in ANN model for training process with feed forward learning procedure. The aim of this work is to examine the performance and comparison of four training functions (TRAINCGP, TRAINSCG, TRAINLM and TRAINOSS) applied in training process of neural model. A comparison was based on the RMSE and R 2 . It was found that training function TRAINLM exhibits optimal result with the experimental data.
Achintya Mukhopadhyay - One of the best experts on this subject based on the ideXlab platform.
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Impact of side injection on heat removal from truncated conical heat-generating Porous Bed: thermal non-equilibrium approach
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Aranyak Chakravarty, Nirmalendu Biswas, Koushik Ghosh, Nirmal K. Manna, Achintya MukhopadhyayAbstract:Effective removal of heat from the heat-generating Porous Bed, particularly in a confined space, is essential due to its implications on thermal management and system safety. The safety aspect becomes particularly important during post-accident heat removal from decay heat-generating debris in nuclear reactors, as well as thermal management of self-igniting coal stockpiles. In spite of detailed research on thermal convection through Porous media, only a handful of studies have considered mixed convective heat transport involving heat-generating Porous Bed along with external fluid injection. The situation, however, demands an in-depth analysis due to the associated practical implications. The present work addresses one cooling method providing side injection of cold fluid and assuming a typical conical heat-generating Porous Bed located centrally within a fluid-filled cylindrical enclosure. The study is carried out in a general way to suit other applications. The dimensionless governing equations, along with the boundary conditions in a two-dimensional coordinate system, are solved numerically assuming laminar and incompressible flow along with the Boussinesq approximation. The analysis is carried utilizing the local thermal non-equilibrium model within the Porous Bed. Injection of cold fluid can markedly affect the convective heat transport rate. Porous media permeability considerably influences the flow mechanism. The major findings of this study can be very useful in improving the management of thermal energy removal from self-igniting coal stockpiles, grain storages, Porous debris, etc. Heat transport intensification from heat-generating Porous Bed is analyzed by injecting coolant through the sidewall and considering liquid water as the working medium. The impacts of pertinent parameters on the thermal convection characteristics are illustrated using the average Nusselt number and energy flux vectors.
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Mixed convective heat transfer in an enclosure containing a heat-generating Porous Bed under the influence of bottom injection
International Journal of Heat and Mass Transfer, 2018Co-Authors: Aranyak Chakravarty, Koushik Ghosh, Priyankan Datta, Swarnendu Sen, Achintya MukhopadhyayAbstract:Abstract The present study numerically models the process of heat removal from a heat-generating Porous Bed with cold fluid injection from the bottom of the Bed. This type of situation is encountered during post-accident situations in nuclear reactors and involves augmentation of heat removal capacity with forced coolant injection from the bottom. A steady-state analysis is carried out with the assumption of laminar flow regime and without accounting for phase change. Darcy-Brinkmann-Forchheimer approximation and local thermal equilibrium assumption are adopted for modelling the momentum and energy equations in Porous media, respectively. It is observed that the fluid flow is determined based on the dominancy of the two co-existing flow mechanisms viz. inertial flow due to forced fluid injection and buoyancy-driven flow due to heat generation within the Porous Bed. In addition, permeability of the Porous media significantly affects the flow mechanism, especially near the fluid inlet. Heat transfer characteristics closely follow the flow mechanism established within the enclosure.
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thermal non equilibrium heat transfer and entropy generation due to natural convection in a cylindrical enclosure with a truncated conical heat generating Porous Bed
Transport in Porous Media, 2017Co-Authors: Aranyak Chakravarty, Koushik Ghosh, Priyankan Datta, Swarnendu Sen, Achintya MukhopadhyayAbstract:Natural convection in enclosures driven by heat-generating Porous media has diverse applications in fields like geothermal, chemical, thermal and nuclear energy. The present article focuses on heat transfer and entropy generation characteristics of a heat-generating Porous Bed, placed centrally within a fluid-filled cylindrical enclosure. Pressure drop and heat transfer in the Porous Bed are modelled using the Darcy–Brinkmann–Forchheimer approximation and the local thermal non-equilibrium model, respectively. Energy flux vectors have been utilised for visualising convective energy transfer within the enclosure. The study of a wide range of Rayleigh number (\(10^{7}\)–\(10^{11}\)) and Darcy number (\(10^{-6}\)–\(10^{-10}\)) reveals that heat transfer in the Porous region can be classified into conduction-dominated and convection-dominated regimes. This is supplemented with an entropy generation analysis in order to identify and characterise the irreversibilities associated with the phenomenon. It is observed that entropy generation characteristics of the enclosure closely follow the above-mentioned regime demarcation. Numerical computations for the present study have been conducted using ANSYS FLUENT 14.5. The solid energy equation is solved as a user-defined scalar equation, while data related to energy flux vectors and entropy generation are obtained using user-defined functions.
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Numerical analysis of a heat-generating, truncated conical Porous Bed in a fluid-filled enclosure
Energy, 2016Co-Authors: Aranyak Chakravarty, Koushik Ghosh, Priyankan Datta, Swarnendu Sen, Achintya MukhopadhyayAbstract:Abstract Analysis of natural convection in enclosures containing heat generating Porous medium has important applications related to geothermal, chemical, thermal and nuclear energy such as in-vessel cooling of debris Beds in nuclear reactors, cooling of coal stockpiles etc. The objective of the present numerical study is to characterise the pattern of fluid flow and energy transfer during steady laminar natural convective flow in a cylindrical enclosure with a centrally placed heat generating Porous Bed. Flow through Porous region is modelled using Darcy–Brinkmann–Forchheimer model and local thermal equilibrium is assumed for the Porous region. Analysis is carried out for a wide range of Rayleigh number ( Ra ), Darcy number ( Da ) and thermal conductivity ratio, as well as for different Bed geometries. It is observed that in addition to Ra and Da , the Bed geometry also plays a very important role in determining flow field and temperature distribution within the enclosure. Interestingly, a significant change is observed in energy transfer mode from the Porous Bed corresponding to specific values of Bed permeability and Bed heat generation rate. This is characterised in terms of Ra and Da . Further, it is observed that this change in energy transfer mode is highly dependent on Ra .
Harish Kumar Ghritlahre - One of the best experts on this subject based on the ideXlab platform.
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investigation of thermal performance of unidirectional flow Porous Bed solar air heater using mlp grnn and rbf models of ann technique
Thermal science and engineering, 2018Co-Authors: Harish Kumar Ghritlahre, Radha Krishna PrasadAbstract:Abstract In the present work, Multi-layer perceptron (MLP), Generalized regression neural network (GRNN), Radial basis function (RBF) and Multiple linear regression (MLR) models has been used to predict the thermal performance of unidirectional flow Porous Bed solar air heater. These four models have been constructed on the basis of actual experimental data and calculated values. Total 96 experimental data sets have been used in the present work. In GRNN, RBF and MLP models, six input parameters such as mass flow rate, wind speed, atmospheric temperature, inlet fluid temperature, fluid mean temperature and solar intensity were used in input layer, and one variable, the thermal efficiency was used in output layer. Same parameters were used in MLR model. It is observed that GRNN model is the best model due to lowest error and highest value of R2 as compared to MLP, RBF and MLR model performances. It is found that the value of MAE, RMSE and R2 for GRNN model are 1.1128E−03, 5.9284E−06 and 0.99758 respectively, and the model efficiency is 0.99760, which is the highest value as compared to other model. These results confirmed that the GRNN model is appropriate model to predict the thermal performance of solar air heater.
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prediction of thermal performance of unidirectional flow Porous Bed solar air heater with optimal training function using artificial neural network
Energy Procedia, 2017Co-Authors: Harish Kumar Ghritlahre, Radha Krishna PrasadAbstract:Abstract In the present work, Artificial Neural Network (ANN) has been used to predict the thermal performance of unidirectional flow Porous Bed solar air heater. The ANN model was structured on the basis of data sets obtained from experiments and values of thermal efficiency of solar air heater. Four types of training functions are used in ANN model for training process with feed forward learning procedure. The aim of this work is to examine the performance and comparison of four training functions (TRAINCGP, TRAINSCG, TRAINLM and TRAINOSS) applied in training process of neural model. A comparison was based on the RMSE and R 2 . It was found that training function TRAINLM exhibits optimal result with the experimental data.
Aranyak Chakravarty - One of the best experts on this subject based on the ideXlab platform.
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Impact of side injection on heat removal from truncated conical heat-generating Porous Bed: thermal non-equilibrium approach
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Aranyak Chakravarty, Nirmalendu Biswas, Koushik Ghosh, Nirmal K. Manna, Achintya MukhopadhyayAbstract:Effective removal of heat from the heat-generating Porous Bed, particularly in a confined space, is essential due to its implications on thermal management and system safety. The safety aspect becomes particularly important during post-accident heat removal from decay heat-generating debris in nuclear reactors, as well as thermal management of self-igniting coal stockpiles. In spite of detailed research on thermal convection through Porous media, only a handful of studies have considered mixed convective heat transport involving heat-generating Porous Bed along with external fluid injection. The situation, however, demands an in-depth analysis due to the associated practical implications. The present work addresses one cooling method providing side injection of cold fluid and assuming a typical conical heat-generating Porous Bed located centrally within a fluid-filled cylindrical enclosure. The study is carried out in a general way to suit other applications. The dimensionless governing equations, along with the boundary conditions in a two-dimensional coordinate system, are solved numerically assuming laminar and incompressible flow along with the Boussinesq approximation. The analysis is carried utilizing the local thermal non-equilibrium model within the Porous Bed. Injection of cold fluid can markedly affect the convective heat transport rate. Porous media permeability considerably influences the flow mechanism. The major findings of this study can be very useful in improving the management of thermal energy removal from self-igniting coal stockpiles, grain storages, Porous debris, etc. Heat transport intensification from heat-generating Porous Bed is analyzed by injecting coolant through the sidewall and considering liquid water as the working medium. The impacts of pertinent parameters on the thermal convection characteristics are illustrated using the average Nusselt number and energy flux vectors.
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Mixed convective heat transfer in an enclosure containing a heat-generating Porous Bed under the influence of bottom injection
International Journal of Heat and Mass Transfer, 2018Co-Authors: Aranyak Chakravarty, Koushik Ghosh, Priyankan Datta, Swarnendu Sen, Achintya MukhopadhyayAbstract:Abstract The present study numerically models the process of heat removal from a heat-generating Porous Bed with cold fluid injection from the bottom of the Bed. This type of situation is encountered during post-accident situations in nuclear reactors and involves augmentation of heat removal capacity with forced coolant injection from the bottom. A steady-state analysis is carried out with the assumption of laminar flow regime and without accounting for phase change. Darcy-Brinkmann-Forchheimer approximation and local thermal equilibrium assumption are adopted for modelling the momentum and energy equations in Porous media, respectively. It is observed that the fluid flow is determined based on the dominancy of the two co-existing flow mechanisms viz. inertial flow due to forced fluid injection and buoyancy-driven flow due to heat generation within the Porous Bed. In addition, permeability of the Porous media significantly affects the flow mechanism, especially near the fluid inlet. Heat transfer characteristics closely follow the flow mechanism established within the enclosure.
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thermal non equilibrium heat transfer and entropy generation due to natural convection in a cylindrical enclosure with a truncated conical heat generating Porous Bed
Transport in Porous Media, 2017Co-Authors: Aranyak Chakravarty, Koushik Ghosh, Priyankan Datta, Swarnendu Sen, Achintya MukhopadhyayAbstract:Natural convection in enclosures driven by heat-generating Porous media has diverse applications in fields like geothermal, chemical, thermal and nuclear energy. The present article focuses on heat transfer and entropy generation characteristics of a heat-generating Porous Bed, placed centrally within a fluid-filled cylindrical enclosure. Pressure drop and heat transfer in the Porous Bed are modelled using the Darcy–Brinkmann–Forchheimer approximation and the local thermal non-equilibrium model, respectively. Energy flux vectors have been utilised for visualising convective energy transfer within the enclosure. The study of a wide range of Rayleigh number (\(10^{7}\)–\(10^{11}\)) and Darcy number (\(10^{-6}\)–\(10^{-10}\)) reveals that heat transfer in the Porous region can be classified into conduction-dominated and convection-dominated regimes. This is supplemented with an entropy generation analysis in order to identify and characterise the irreversibilities associated with the phenomenon. It is observed that entropy generation characteristics of the enclosure closely follow the above-mentioned regime demarcation. Numerical computations for the present study have been conducted using ANSYS FLUENT 14.5. The solid energy equation is solved as a user-defined scalar equation, while data related to energy flux vectors and entropy generation are obtained using user-defined functions.
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Numerical analysis of a heat-generating, truncated conical Porous Bed in a fluid-filled enclosure
Energy, 2016Co-Authors: Aranyak Chakravarty, Koushik Ghosh, Priyankan Datta, Swarnendu Sen, Achintya MukhopadhyayAbstract:Abstract Analysis of natural convection in enclosures containing heat generating Porous medium has important applications related to geothermal, chemical, thermal and nuclear energy such as in-vessel cooling of debris Beds in nuclear reactors, cooling of coal stockpiles etc. The objective of the present numerical study is to characterise the pattern of fluid flow and energy transfer during steady laminar natural convective flow in a cylindrical enclosure with a centrally placed heat generating Porous Bed. Flow through Porous region is modelled using Darcy–Brinkmann–Forchheimer model and local thermal equilibrium is assumed for the Porous region. Analysis is carried out for a wide range of Rayleigh number ( Ra ), Darcy number ( Da ) and thermal conductivity ratio, as well as for different Bed geometries. It is observed that in addition to Ra and Da , the Bed geometry also plays a very important role in determining flow field and temperature distribution within the enclosure. Interestingly, a significant change is observed in energy transfer mode from the Porous Bed corresponding to specific values of Bed permeability and Bed heat generation rate. This is characterised in terms of Ra and Da . Further, it is observed that this change in energy transfer mode is highly dependent on Ra .
Stephen Wilson - One of the best experts on this subject based on the ideXlab platform.
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Squeeze-film flow between a curved impermeable bearing and a flat Porous Bed
Physics of Fluids, 2017Co-Authors: D. J. Knox, Brian Duffy, Sean Mckee, Stephen WilsonAbstract:Axisymmetric squeeze-film flow in the thin gap between a stationary flat thin Porous Bed and a curved impermeable bearing moving under a prescriBed constant load is analysed. The unsteady Reynolds equation is formulated and solved for the fluid pressure. This solution is used to obtain the time for the minimum fluid layer thickness to reduce to a given value, and, in particular, the finite time for the bearing and the Bed to come into contact. The effect of varying the shape of the bearing and the permeability of the layer is investigated, and, in particular, it is found that both the contact time and the fluid pressure behave qualitatively differently for Beds with small and large permeabilities. In addition, the paths of fluid particles initially situated in both the fluid layer and the Porous Bed are calculated. In particular, it is shown that, unlike in the case of a flat bearing, for a curved bearing there are fluid particles, initially situated in the fluid layer, that flow from the fluid layer into...
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Porous squeeze-film flow
IMA Journal of Applied Mathematics, 2013Co-Authors: D. J. Knox, Stephen Wilson, Brian Duffy, S. MckeeAbstract:The squeeze-film flow of a thin layer of Newtonian fluid filling the gap between a flat impermeable surface moving under a prescriBed constant load and a flat thin Porous Bed coating a stationary flat impermeable surface is considered. Unlike in the classical case of an impermeable Bed, in which an infinite time is required for the two surfaces to touch, for a Porous Bed contact occurs in a finite contact time. Using a lubrication approximation an implicit expression for the fluid layer thickness and an explicit expression for the contact time are obtained and analysed. In addition, the fluid particle paths are calculated, and the penetration depths of fluid particles into the Porous Bed are determined. In particular, the behaviour in the asymptotic limit of small permeability, in which the contact time is large but finite, is investigated. Finally, the results are interpreted in the context of lubrication in the human knee joint, and some conclusions are drawn about the contact time of the cartilage-coated femoral condyles and tibial plateau and the penetration of nutrients into the cartilage.