Faculty Publications
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Item Linear thermal buckling and free vibration analysis are presented for functionally graded cylindrical shells with clamped-clamped boundary condition based on temperature-dependent material properties. The material properties of functionally graded materials (FGM) shell are assumed to vary smoothly and continuously across the thickness. With high-temperature specified on the inner surface of the FGM shell and outer surface at ambient temperature, 1D heat conduction equation along the thickness of the shell is applied to determine the temperature distribution; thereby, the material properties based on temperature distribution are made available for thermal buckling and free vibration analysis. First-order shear deformation theory along with Fourier series expansion of the displacement variables in the circumferential direction are used to model the FGM shell. Numerical studies involved the understanding of the influence of the power-law index, r/h and l/r ratios on the critical buckling temperature. Free vibration studies of FGM shells under elevated temperature show that the fall in natural frequency is very drastic for the mode corresponding to the lowest natural frequency when compared to the lowest buckling temperature mode. © 2005 Elsevier Ltd. All rights reserved.(Academic Press, Buckling and free vibration analysis of functionally graded cylindrical shells subjected to a temperature-specified boundary condition) Kadoli, R.; Ganesan, N.2006Item 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 Experimental and theoretical investigations on the cyclic operation of TSA cycle for air dehumidification using packed beds of silica gel particles(Elsevier Ltd, 2013) Ramzy K, A.K.; Kadoli, R.; Ashok Babu, T.P.Dehumidification using desiccant beds provide a good alternative for the conventional vapor compression cooling system. Desiccant material in the desiccant dehumidification system should undergo both adsorption and desorption processes. In the present work, experimental tests have been carried out for thermal swing adsorption (TSA) cycle utilizing two packed beds of silica gel spherical particles. The pseudo gas side controlled (PGC) mathematical model has been presented for predicting the cycle performance. The mathematical model has been validated using the experimental results. The root mean square of errors ranges from 1.15% to 9.03% for the exit air humidity ratio and from 1.08% to 9.68% for exit air temperature. The dynamics of desiccant bed during the cyclic operation has been investigated numerically. In addition, it has been found from the parametric study that the cycle efficiency is maximum for a regeneration temperature of 90-95°C when the bed length varies from 50 to 300mm and for desiccant particle diameter ranging from 2 to 5mm. A sensible cooling for the process air before undergoing the dehumidification period is recommended for increasing the cycle efficiency and the dehumidification time which is an added advantage. © 2013 Elsevier Ltd.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.