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Ravikiran Kadoli - One of the best experts on this subject based on the ideXlab platform.

  • experimental and theoretical study on dehumidification potential of clay additives based cacl2 composite Desiccants
    Applied Thermal Engineering, 2018
    Co-Authors: C R Hiremath, Ravikiran Kadoli, V V Katti
    Abstract:

    Abstract Transported clay suitable for pot making is used as Desiccant carrier. Additives like saw dust and horse dung are considered in particle preparation. Particles nearly spherical in shape are prepared manually and are dried under shadow and subsequently the particles are dried at different temperatures. These burnt particles are characterized for pore volume and surface area. The BET test reveals that clay particles subjected to 500 °C possess higher pore volume but clay-horse dung particles exhibit higher surface area. Heat treated particles of clay with additives are impregnated with CaCl 2 solution of 50% concentration. The ratio of Desiccant water content to surrounding layer water content varies from 14.09 to 75.34 for CaCl 2 based composite Desiccants. One dimensional PGC mass transfer model for process air through burnt clay – additives - CaCl 2 Desiccant Bed is adopted. The RMSE of measured and predicted results for reduction of moisture content from the process air by composite Desiccant Beds are in the range of 3.26–13.2%.

  • modified pgc model and its validation by experiments for heat and moisture transfer analysis in a vertical fluidized Desiccant Bed
    Applied Thermal Engineering, 2015
    Co-Authors: Ahmed Ramzy, Ravikiran Kadoli
    Abstract:

    Abstract Air dehumidification in fluidized Beds utilizing Desiccants is an alternative for the refrigeration methods. A variety of pseudo gas controlled (PGC) model are proposed by assuming constant and varying temperature as well as water content for the solid phase to evaluate the conditions of exit air during adsorption processes. Experimental tests for moisture adsorption in silica gel fluidized Bed are carried out. The modified PGC model that assumes uniform water content, varying temperature and linear porosity distributions along the Bed estimates the temporal average Bed water content to agree very well with the experimental data. The RMSE of the numerical results of the present model ranges from 0.2 to 6% and that obtained from the isothermal model are in the range of 6%–68%.

  • significance of axial heat conduction in non isothermal adsorption process in a Desiccant packed Bed
    International Journal of Thermal Sciences, 2014
    Co-Authors: K A Ramzy, Ravikiran Kadoli, T Ashok P Babu
    Abstract:

    Abstract 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.

Noam Lior - One of the best experts on this subject based on the ideXlab platform.

  • transient two dimensional dehumidification and desorption behavior of plate Desiccants under humid air flow a conjugate model that includes diffusion and adsorption desorption within the Desiccant
    Industrial & Engineering Chemistry Research, 2011
    Co-Authors: Hassan S Alsharqawi, Noam Lior
    Abstract:

    A more rigorous conjugate-transient two-dimensional numerical model of solid Bed Desiccant systems (plates and narrow channels) used for gas dehumidification of a gas laminarly flowing along the Desiccant, which, importantly, includes the associated transport through the Desiccant body, was developed and validated. This improvement of the basic understanding of the process can be used for easier determination of ways for improving the overall performance of such systems. The solution provided a detailed exposition of the associated heat- and mass-transfer phenomena and of the Desiccant performance, conducted here for both the adsorption and desorption processes in a range of air-flow Reynolds numbers and Desiccant Bed particle sizes and for two types of Desiccant materials, silica gel and polystyrenesulfonic acid sodium salt (PSSASS) polymer. The results were also compared to those from an authors’ simpler model that was published earlier and that does not consider transport through the solid Desiccant. T...

  • ARTICLE pubs.acs.org/IECR Transient Two-Dimensional Dehumidification and Desorption Behavior of Plate Desiccants under Humid Air Flow: a Conjugate Model That Includes Diffusion and Adsorption/Desorption within
    2011
    Co-Authors: The Desiccant, Hassan S. Al-sharqawi, Noam Lior
    Abstract:

    ABSTRACT: A more rigorous conjugate-transient two-dimensional numerical model of solid Bed Desiccant systems (plates and narrow channels) used for gas dehumidification of a gas laminarly flowing along the Desiccant, which, importantly, includes the associated transport through the Desiccant body, was developed and validated. This improvement of the basic understanding of the process can be used for easier determination of ways for improving the overall performance of such systems. The solution provided a detailed exposition of the associated heat- and mass-transfer phenomena and of the Desiccant performance, conducted here for both the adsorption and desorption processes in a range of air-flowReynolds numbers and Desiccant Bed particle sizes and for two types of Desiccant materials, silica gel and polystyrenesulfonic acid sodium salt (PSSASS) polymer. The results were also compared to those from an authors ’ simpler model that was published earlier and that does not consider transport through the solid Desiccant. The new model was also employed to define and compute an “effective diffusion coefficient ” from the basic composition of the Desiccant, which is useful for characterizing Desiccant properties and behavior in practical analysis. Besides the detailed behavior, some of the practical results are as follows: (i) the adsorption/desorption processes occur much faster at the flow entrance region; (ii) the mass-transport rates increase with the Reynolds number; (iii) within the studied range, manufacturing of the solid Desiccant from larger particles raises its mass-transport rates; (iv) the water content and adsorption rate for PSSASS are larger than those for silica gel, thus making PSSASS a more effective Desiccant than silica gel. 1

Sassi Ben Nasrallah - One of the best experts on this subject based on the ideXlab platform.

  • Performance of a new Desiccant Bed using phase change material
    'EDP Sciences', 2020
    Co-Authors: Boutheina Zallama, Leila Zili Ghedira, Sassi Ben Nasrallah
    Abstract:

    The main objective of this study was to conduct an experimental analysis to investigate the performance of a new Desiccant Bed. Therefore, tests were carried out in a desiccator filled with a porous media, i.e. silica gel used as Desiccant enhanced with phase change material, using variable inlet climate conditions. Experimental tests were performed to assess the effect of the new packed Bed on the adsorption capacity and this by evaluating the outlet evolutions of temperature, relative humidity and absolute humidity. The experimental setup used in this study is a blower enabling to adjust the flow rate, temperature and relative humidity. The amount of adsorBed mass of moisture is also measured and discussed

  • solid Desiccant solar air conditioning unit in tunisia numerical study
    International Journal of Refrigeration-revue Internationale Du Froid, 2017
    Co-Authors: Ahlem Zouaoui, Leila Zilighedira, Sassi Ben Nasrallah
    Abstract:

    Abstract In this paper, a method for the provision of the human thermal comfort through solar activated solid Desiccant cooling technologies is discussed. These technologies were numerically studied under different Tunisian climatic conditions (relatively cold and humid: Bizerte; hot and dry: Remeda; moderate: Djerba). The studied solid Desiccant cooling is based on the use of a fixed solid Desiccant Bed instead of a rotary Desiccant wheel. The development of the mathematical equations modeling the functioning of the different components (solid fixed Bed, heat exchanger, humidifier, solar collector) is based on heat and mass transfers' balances. Results showed good functioning and applicability of these studied systems for various outdoor conditions of the major Tunisian cities.

  • open solid Desiccant cooling air systems a review and comparative study
    Renewable & Sustainable Energy Reviews, 2016
    Co-Authors: Ahlem Zouaoui, Leila Zilighedira, Sassi Ben Nasrallah
    Abstract:

    Abstract The present work is an overview of new methods aimed to provide air conditioning while avoiding CFC emissions by using low grade energy such as solar energy or waste heat. It deals as well with heat and mass transfers in these installations; the Desiccant cooling installations composed mainly of a Desiccant Bed, a heat exchanger and a humidifier. The ventilated air is cooled through these installations to reduce its temperature and adjust its humidity. In this study a cylindrical fixed Bed is used instead of a Desiccant wheel. The liability and efficiency of the established numerical tool was tested and validated by comparison against numerical and experimental works from the literature. The aim is to give insight on the different Desiccant cooling installations by a general literature survey and also to study numerically different configurations of Desiccant cooling systems. The temporal evolution of air temperature and humidity at the exit of each element of the Desiccant cooling installations were plotted and analyzed.

V V Katti - One of the best experts on this subject based on the ideXlab platform.

  • experimental and theoretical study on dehumidification potential of clay additives based cacl2 composite Desiccants
    Applied Thermal Engineering, 2018
    Co-Authors: C R Hiremath, Ravikiran Kadoli, V V Katti
    Abstract:

    Abstract Transported clay suitable for pot making is used as Desiccant carrier. Additives like saw dust and horse dung are considered in particle preparation. Particles nearly spherical in shape are prepared manually and are dried under shadow and subsequently the particles are dried at different temperatures. These burnt particles are characterized for pore volume and surface area. The BET test reveals that clay particles subjected to 500 °C possess higher pore volume but clay-horse dung particles exhibit higher surface area. Heat treated particles of clay with additives are impregnated with CaCl 2 solution of 50% concentration. The ratio of Desiccant water content to surrounding layer water content varies from 14.09 to 75.34 for CaCl 2 based composite Desiccants. One dimensional PGC mass transfer model for process air through burnt clay – additives - CaCl 2 Desiccant Bed is adopted. The RMSE of measured and predicted results for reduction of moisture content from the process air by composite Desiccant Beds are in the range of 3.26–13.2%.

Ahmed M Hamed - One of the best experts on this subject based on the ideXlab platform.

  • application of solar energy for recovery of water from atmospheric air in climatic zones of saudi arabia
    Natural Resources, 2011
    Co-Authors: Ahmed M Hamed, Elshafei B Zeidan
    Abstract:

    In the present work, an investigation on the application of solar energy to heat a sandy Bed impregnated with calcium chloride for recovery of water from atmospheric air is presented. The study also aimed at evaluating the effects of different parameters on the productivity of the system during regeneration. These parameters include system design characteristics and the climatic conditions. An experimental unit has been designed and installed for this purpose in climatic conditions of Taif area, Saudi Arabia. The experimental unit which has a surface area of 0.5 m 2 , comprises a solar/Desiccant collector unit containing sandy Bed impregnated with calcium chloride. The sandy layer impregnated with Desiccant is subjected to ambient atmosphere to absorb water vapor in the night. During the sunshine period, the layer is covered with glass layer where Desiccant is regenerated and water vapor is condensed on the glass surface. Ambient temperature, Bed temperature and temperature of glass surface are recorded. Also, the productivity of the system has been evaluated. Desiccant concentration at start of regeneration is selected on the basis of the climatic data of Al-Hada region, which is located at Taif area, Saudi Arabia. Experimental measurements show that about 1.0 liter per m 2 of pure water can be regenerated from the Desiccant Bed at the climatic conditions of Taif. Liquid Desiccant with initial concentration of 30% can be regenerated to a final concentration of about 44%. Desiccant concentration at start of regeneration is selected on the basis of the climatic data of Al-Hada region. The climate of Taif city is dry compared with that for Al-Hada region. This method for extracting water from atmospheric air is more suitable for Al-Hada region especially in the fall and winter.

  • theoretical and experimental investigation on the radial flow Desiccant dehumidification Bed
    Applied Thermal Engineering, 2008
    Co-Authors: M M Awad, Ahmed M Hamed, M M Bekheit
    Abstract:

    In the present work, a theoretical and experimental investigation of the radial flow solid Desiccant dehumidifier has been reported. In the experimental study, spherical particles of silica gel (indicating type) of 3 mm average diameter were used as the working Desiccant in the dehumidifier. The Bed under investigation was of radial flow and cylindrical shape. Five experimental test units of hollow cylindrical Bed with different values of diameter ratio were used. For all units, the total mass of dry silica gel in the Bed was nearly the same. In the theoretical part of this study, a mathematical model has been developed and its output results were compared with the experimental data. The effect of Bed design parameters on the Desiccant Bed dynamic performance was discussed. Results show that for efficient operation of the hollow cylindrical Bed, dehumidification period is limited to 15 min for the diameter ratio of 7.2. This period increases with decrease in air flow rate and Bed diameter ratio. The increase in diameter ratio increases the pressure drop within the Bed and rises the Bed adsorption capacity for short operation periods. This analysis allows us to identify and quantify the energy losses in the air blowing system for the specified dehumidification capacity of the Desiccant Bed.

  • application of a solar Desiccant collector system for water recovery from atmospheric air
    Renewable Energy, 2001
    Co-Authors: Ahmed M Hamed, Ibrahim I Elsharkawy
    Abstract:

    An integrated Desiccant/solar collector system for production of fresh water from atmospheric air is descriBed. The solar driven system provided about 1.5 l of fresh water per square meter per day. The system involves the absorption of water vapor from ambient air during the night and simultaneous Desiccant regeneration and water vapor condensation during the day. To enhance the mass transfer surface, a thick corrugated layer of cloth was used as a Bed to carry the liquid absorbent. In the nocturnal phase of operation, air is allowed to penetrate the Desiccant Bed. The airflow is driven by fans supported on one side of the Desiccant/solar collector unit. In this study, the effects of different parameters on the absorption and regeneration processes are discussed, and operational conditions for the proposed equipment evaluated. Radiation intensity, ambient temperature, Bed temperature and temperature of the glass surface were recorded. Also, the productivity of the system during the day and under the given operation conditions was plotted. A mathematical model was prepared and its output compared with the analyzed experimental data.