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High potential of employing bentonite in adsorption cooling systems driven by low grade heat source temperatures

: Askalany, A.A.; Ernst, S.-J.; Hügenell, P.P.C.; Bart, H.-J.; Henninger, S.K.; Alsaman, A.S.


Energy 141 (2017), pp.782-791
ISSN: 0360-5442
Journal Article
Fraunhofer ISE ()
Thermische Anlagen und Gebäudetechnik; Gebäudeenergietechnik; Materialien und Komponenten für Wärmetransformation

In this research article a new modified adsorbent has been presented to be used in thermally driven adsorption systems for renewable energy applications. Bentonite is introduced as a cheap adsorbent with high potential for use in heat pumps or chillers driven by renewable energy. A simple acid activation procedure increases the inner surface of the material and also enhances the water adsorption capacity markedly. The raw bentonite is activated with different concentrations (0.2, 0.4, 0.6 mol L−1) of HCl. FT-IR, XRD, N2 adsorption, water adsorption and heat capacity measurements have been carried out for the raw and HCl activated bentonite. The acid activation process increased the surface area of the bentonite from 64 m2 g−1 to a level of 500 m2 g−1. In that respect the maximum adsorption capacity has markedly increased by the acid activation. Experimental and theoretical studies for the adsorption isotherms and kinetics at different adsorption temperatures of water vapor onto 0.6 HCl treated bentonite have been conducted. A simulation for an adsorption cooling system employing treated bentonite has been presented. The performance of the modeled system has been also studied to be driven by low grade heat source temperatures at different operating conditions.