Faculty Publications
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Item Semi-analytical method for heat and moisture transfer in packed bed of silica gel(2011) Ramzy K, A.; Ashok Babu, T.P.; Kadoli, R.A semi-analytical model for the heat and mass transfer of adsorption and desorption processes of the vertical solid desiccant packed bed dehumidifier is presented on the basis of quasi-steady state assumption, and is solved using close form integration with the limits equivalent to bed and time increments, and numerically by Runge-Kutta Fehlberg and forward scheme finite difference techniques. The most important parameters during the dehumidifier operation, namely, (i) exit air temperature and humidity, (ii) axial temperature distribution in the bed and (iii) water content are evaluated. Stability of the semi-analytical method is investigated and found that the main parameters affecting the model stability are the bed and time increments size. A dimensionless parameter combining time and bed increments size and air velocity named velocity ratio is defined and investigated. It is found that when the velocity ratio equals the ratio of particle diameter to bed length, the method is stable, and as the velocity ratio is made smaller beyond the stable velocity ratio, the results remain unchanged. The results of semi-analytical and numerical models agree well with the experimental results for both desorption and adsorption processes. Using the proposed semi-analytical model, the minimum and maximum relative errors for exit air temperature are 2.24% and 11.78%, respectively and for exit air humidity the minimum and maximum errors are 3.79% and 27.17% respectively. © 2010 Published by Elsevier Ltd. All rights reserved.Item Performance studies on the desiccant packed bed with varying particle size distribution along the bed(2012) Ramzy K, A.; Kadoli, R.; Ashok Babu, T.P.The transient heat and mass transfer in a desiccant packed bed containing varying particle diameter distribution along the axial direction has been investigated using the pseudo gas controlled approach that considers the heat conduction in the bed. The numerical results of the present model and the experimental data from literature show good agreement with a maximum root of mean square of errors of 3% and 2% for exit air temperature and humidity ratio, respectively. The improvement in the total mass adsorbed and/or reduction in pressure drop has been investigated for various cases of packed bed namely, uniform particle diameter, linear, parabolic and cubic ascending and descending distributions. It has been found that there is a 25.7% reduction in pressure drop with negligible reduction in the total mass adsorbed for a desiccant bed with cubic type particle size distribution when compared to the bed with uniform particle diameter of 1.0 mm. A threshold flow velocity exists below which the total mass adsorbed is independent of particle diameter distribution type. © 2012 Elsevier Ltd and IIR. All rights reserved.Item Significance of axial heat conduction in non-isothermal adsorption process in a desiccant packed bed(2014) Ramzy, K.A.; Kadoli, R.; Ashok Babu, T.P.Numerical simulation of heat and moisture interactions between air stream and the particles in a desiccant bed provide useful insight on the dynamics of the bed and performance characteristics. Current study introduces a mathematical model for the heat and moisture transfer in desiccant packed bed based on solid side resistance (SSR) model that will now consider heat conduction along the bed. Adsorption and desorption experimental tests have been carried out for validating both solid side resistance (SSR) and solid side resistance with axial heat conduction (SSR-AC) models. The models have been used to investigate the influence of various design parameters like air velocity, particle diameter, bed length and the number of units of mass transfer, on the significance of axial heat conduction. It has been found that increasing the particle diameter or increasing air flow velocity or decreasing the bed length will reduce the influence of axial heat conduction in the bed. Moreover, it has been found that the difference in the bed performance evaluated due to the absence of axial heat conduction in the bed is notably decreasing with the decrease in the number of transfer units of heat or mass. From this study, it is recommended to consider the axial heat conduction term when number of transfer units of mass and heat are greater than unity. © 2013 Elsevier Masson SAS. All rights reserved.Item Control force and inertial migration in Poiseuille flow: a computational study(Taylor and Francis Ltd., 2023) Neeraj, M.P.; Maniyeri, R.The present work deals with the development of a numerical model to analyze the effect of control force on a single rigid massive cylindrical particle’s lateral migration in a straight channel. The finite volume immersed boundary method (feedback forcing-based), along with semi-implicit strategy, is incorporated to create a computational model. The control force is applied in the direction against the fluid flow, to control the equilibrium position and drive it to the channel center. The effect of the Reynolds number, particle diameter and density ratio on the control force is studied. From parametric studies, a prediction model is developed for the control force with the Reynolds number, particle diameter and density ratio as inputs. The linear regression methodology in machine learning is utilized to create the prediction model. The predicted values of control force are observed to match those of the simulation results. © 2023 Taylor & Francis Group, LLC.Item Lateral migration of cylindrical particle in a constricted microchannel—A numerical study(John Wiley and Sons Inc, 2023) Neeraj, M.P.; Maniyeri, R.Inertial migration of a single cylindrical particle in a constricted microchannel is addressed in this work. A computational model (two-dimensional) has been constructed with the assistance of the immersed boundary finite volume method. The feedback forcing strategy is utilized for the simulation of lateral migration. The parameters like equilibrium position, migration time, and shortest equilibrium distance are computed to analyze the inertial migration characteristics of the particle. Also, a comprehensive parametric study has been performed on the migration behaviour of particles inside the constricted channel by addressing the effects of Reynolds number, diameter, initial release position, and constriction clearance. The parametric study shows that the equilibrium position changes with variations in the initial release position and particle diameter. On the other hand, it stays unaffected by changes in Reynolds number and constriction clearance. The parameters like the shortest equilibrium distance and migration time increase with a rise in Reynolds number and particle diameter. On the other hand, it reduces with the reduction in constriction clearance. Inspired by the parametric study results, in the following stage, a prediction model is created with an artificial neural network algorithm. This is used for an effective forecast of equilibrium position, migration time, and shortest equilibrium distance. Further, the computational model is utilized to check for the existence of a critical Reynolds number for the particle movement in a constricted microchannel. It is observed that the critical Reynolds number remains unchanged with a change in particle diameter. However, it increases linearly with an increase in constriction clearance. © 2022 Canadian Society for Chemical Engineering.Item Inertial migration and control force in pulsatile flow- a computational study(Taylor and Francis Ltd., 2024) Neeraj, M.P.; Maniyeri, R.The current work proposes a numerical model for analysing the inertial migration of cylindrical-shaped rigid particles in pulsatile flow. The particle is non-neutrally buoyant, and the numerical model is built using a feedback forcing-based immersed boundary scheme. For shifting particle equilibrium position towards the channel centre, an opposing flow control force is applied. The relationship between control force and parameters such as particle diameter, Reynolds number, and density ratio is thoroughly investigated and reported here. The magnitude of the control force increases with Reynolds number and decreases with particle diameter. With density ratio, on the other hand, the magnitude of the control force first drops and then rises. Based on the results of the parametric study a prediction model for the control force is developed with the help of a linear regression algorithm. © 2024 Indian Institute of Chemical Engineers.