Measurements and theoretical modelling of the effective thermal conductivity of zeolites

The use of zeolites as an adsorbent for water or ammonia in heat pumps and cooling systems is an interesting alternative to the traditional refrigeran ts. Recently, zeolites are also in discussion as hydrogen storage material. For all these applications the effective thermal conductivity of the zeoli tes is an important thermophysical property. The effective thermal conducti vity lambda(eff) was measured by using the transient hot-wire method with a n accuracy of +/-5-15%. The accuracy increases with increasing effective th ermal conductivity. Hydrogen, argon, helium, nitrogen and air were used as filling gas. The gas pressure was varied in the range of 1 mbar less than o r equal to p less than or equal to 30 bar and the temperature in the range of 210 K less than or equal to T less than or equal to 570 K. A simple mode l is proposed to calculate the effective thermal conductivity of the zeolit e powder with an accuracy of about +/-30%. (C) 1999 Elsevier Science Ltd. A ll rights reserved.