Faculty Publications

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    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.
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    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.
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    Economic and environmental benefits of cool pavements: a case study of Bhubaneswar city
    (Springer, 2025) Anupam, B.R.; Chandra Sahoo, U.C.; Vinoj, V.; Rath, P.
    The change of land use from natural lands to built-up areas is one of the key reasons for the urban heat island (UHI) effect, because of absorbance and storing of heat energy. Roads and streets cover a significant fraction of the urban fabric and are continuously exposed to solar radiation. This study examines the impact of pavement surface temperature on urban air temperature. Measurements were made across the Bhubaneswar city to capture the temperature and relative humidity along the major arterial roads. The study quantified the UHI effect and evaluated the benefits of cool pavements in reducing air temperature and improving energy efficiency. The study reveals a strong relation between pavement surface temperature and near-surface air temperature. It was found that up to 1.5 m above the pavement surface, the impact of pavement surface temperature on the air temperature is substantial. On a particularly hot summer day, the air temperature just above the pavement surface and at 1.5 m above the surface was observed to be higher than the surrounding ambient air temperature by up to 7.4 °C and 2 °C, respectively. Based on the measurements taken during this limited period, the peak UHI intensity in Bhubaneswar city was found to be ~ 1.9 °C, which is high, if the current developments of the city are taken into consideration. This study also indicates that significant economic and environmental benefits can be achieved with the adoption of cool pavement technologies. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.