Thermal Conductivity of Methane-Hydrate

TL;DR

This study measures the thermal conductivity of methane hydrate across 2-140 K, revealing amorphous-like behavior and insights into its structure, with results interpreted via the soft-potential model.

Contribution

First measurement of methane hydrate's thermal conductivity over a wide temperature range, analyzing its glass-like behavior and structural implications.

Findings

Thermal conductivity exhibits amorphous solid behavior.

Ice after hydrate separation shows heavily deformed polycrystal characteristics.

Results align with the soft-potential model for amorphous materials.

Abstract

The thermal conductivity of the methane hydrate CH4 (5.75 H2O) was measured in the interval 2-140 K using the steady-state technique. The thermal conductivity corresponding to a homogeneous substance was calculated from the measured effective thermal conductivity obtained in the experiment. The temperature dependence of the thermal conductivity is typical for the thermal conductivity of amorphous solids. It is shown that after separation of the hydrate into ice and methane, at 240 K, the thermal conductivity of the ice exhibits a dependence typical of heavily deformed fine-grain polycrystal. The reason for the glass-like behavior in the thermal conductivity of clathrate compounds has been discussed. The experimental results can be interpreted within the phenomenological soft-potential model with two fitting parameters.