IWNET12
IWNET12
Heat transfer in zeolites determined from non-equilibrium molecular
dynamics simulations
S. K. Schnell1, D. Bedeaux2, S. Kjelstrup1,2, T. J. H. Vlugt1
1 Process and Energy Laboratory, Delft University of Technology, Leeghwaterstaat 44, 2628CA Delft, The
Netherlands
2 Department of Chemistry, Norwegian University of Science and Technology, N-7491 Trondheim, Norway
Abstract
The thermal conductivity of complex crystalline materials is an interesting property, though it can be dicult
to determine both experimentally and computationally. Zeolites are one such material, with its wide selection of
structures, and multitude of pores, channels, and cavities. In this work we have used non-equilibrium molecular
dynamics (NEMD) simulations to study the heat conductivity of a wide range of zeolite systems.
The NEMD method induce a thermal gradient in the system, by simulating elastic collisions between particles in
dierent parts of the simulation box, as described by Müller-Plathe[1]. The heat ux, Jq is determined directly
from the transferred amount of heat, the heat conductivity directly follows from the temperature gradient which
is calculated in the simulation:
λ = − Jq
(12)
dT /dx
Using simulations, we are able to determine how this conductivity depends on the loading of the zeolite, the
forceeld parameters, and the orientation of the crystal. We nd that the orientation of the zeolite is very
important, and in some cases, the conductivity can be twice as large in one crystallographic direction.
Figure 1: Temperature in FER zeolite, under a temperature gradient. The outer left- and right part of the
system is perturbed, and the centre region has a linear temperature-prole.
Conclusion
Using non-equilibrium molecular dynamics, we can screen zeolites, and study the mechanisms for heat transfer
in dierent zeolite structures. The method gives results comparable to experimental results, while the method
is not very computationally intensive.
Acknowledgement
We acknowledge nancial support from NWO-CW through an ECHO grant, and computational resources
were sponsored by the Stichting Nationale Computerfaciliteiten (National Computing Facilities Foundation,
NCF), with nancial support from the Nederlandse Organisatie voor Weten- schappelijk onderzoek (Netherlands
Organization for Scientic Research, NWO).
References
[1] Müller-Plathe, F., A simple nonequilibrium molecular dynamics method for calculating the thermal conduc-
tivity, J. Chem. Phys., 1997, 106, 6082-6085.
E-mail: s.k.schnell@tudelft.nl

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