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Spelling Error in Energy Storage Findings?

  1. Jul 22, 2014 #1
    Hello to all Experts in Adsorption Physics!
    Here is a research paper, stating that water adsorbed in a mineral called bentonite can store as much as 30 kJ/g. According our research and findings with such water based latent heat or phase change storage systems, there seem to be a fatal error published. The correct figure may be 1000times smaller with only 30kJ/kg as enthalpy per mass of heat storage material. See abstracts and publication below. By the way, our PCM has a capacity of 1000kJ/kg. Thanks for looking into this. Johann


    Adsorption/desorption of water vapour on raw Saudi bentonite (RB) is proposed as a heat energy storage. This is most readily achieved by adsorption and desorption of water vapour on RB at different temperatures as a function of time. The RB subjected to preheating temperature of 200 °C, before subjecting to the adsorption process carried out. The IR spectra of RB before adsorption of water vapour at 298 and 313 K were studied. The adsorbed and desorbed water vapour from bentonite surfaces at 298 and 313 K was determined at different time. The adsorptive capacities of RB sample at 298 and 313 K were 0.0097 and 0.0141 mol/g of dry RB, respectively, after 72 h. The desorbed amounts are 0.0085 and 0.01 mol H2O/g of RB at 298 and 313 K, respectively after 72 h. A kinetic models of second order of the adsorption and desorption of water vapour fitted well the experimental data. Application of Van’t Hoff’s law at two temperatures (298 and 313 K) yields the adsorption and desorption enthalpy. The adsorption enthalpy (stored energy) of RB increased with increasing contact time up to 5 h. At this time the maximum enthalpy was about 30 kJ/g dry bentonite, at which the clay has lost all the energy that could be released due to adsorption of water vapours. Then it shows a decrease in sorption energy when the time increases. On the other hand, the desorption enthalpy increases gradually with the increase of the time up to 72 h then become constant, maximum enthalpy was 14.99 kJ/g. The rate of water vapour adsorption was found to be very high so that the extracted energy from the bentonite surface would not be a problem in any practical utilization of this system.

    Energy storage;
    Raw Saudi bentonite;
    Enthalpy of adsorption: kinetic, adsorption and desorption
    Last edited by a moderator: Jul 22, 2014
  2. jcsd
  3. Jul 30, 2014 #2
    I'm sorry you are not finding help at the moment. Is there any additional information you can share with us?
  4. Jul 31, 2014 #3


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    Science Advisor

    Why not contact the author and question the value?

    W.K. Mekhamer nourallha333[at]hotmail[dot]com
    Department of Chemistry, College of Science, P.O. Box 11495, King Saud University, Riyadh 11451, Saudi Arabia
    Tel.: +966 10501963869; fax: +966 14772245.
  5. Jul 31, 2014 #4
    Thanks for the reference. However, i am first looking for a second opinion, not beeing involved.
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