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Thermal conductivity of methane hydrate was measured in hydrate dissociation self-preservation zone by means of the transient plane source(TPS) technique developed by Gustafsson.The sample was formed from 99.9%(volume ratio) methane gas with 280 ppm sodium dodecyl sulfate(SDS) solution under 6.6 MPa and 273.15 K.The methane hydrate sample was taken out of the cell and moved into a low temperature chamber when the conversion ratio of water was more than 90%.In order to measure the thermal conductivity,the sample was compacted into two columnar parts by compact tool at 268.15 K.The measurements are carried out in the temperature ranging from 263.15 K to 271.15 K at atmospheric pressure.Additionally,the relationship between thermal conductivity and time is also investigated at 263.15 K and 268.15 K,respectively.In 24 h,thermal conductivity increases only 5.45% at 268.15 K,but thermal conductivity increases 196.29% at 263.15 K.Methane hydrates exhibit only minimal decomposition at 1 atm and the temperature ranging from 263.15 K to 271.15 K.At 1 atm and 268.15 K,the total gas that evolved after 24 h was amounted to less than 0.71% of the originally stored gas,and this ultra-stability was maintained if the test was lasted for more than two hundreds hours before terminating.
Thermal conductivity of methane hydrate was measured in hydrate dissociation self-preservation zone by means of the transient plane source (TPS) technique developed by Gustafsson. The sample was formed from 99.9% (volume ratio) methane gas with 280 ppm sodium dodecyl sulfate (SDS ) solution under 6.6 MPa and 273.15 K.The methane hydrate sample was taken out of the cell and moved into a low temperature chamber when the conversion ratio of water was more than 90% .In order to measure the thermal conductivity, the sample was compacted into two columnar parts by compact tool at 268.15 K.The measurements are carried out in the temperature ranging from 263.15 K to 271.15 K at atmospheric pressure. Additionally, the relationship between thermal conductivity and time is also investigated at 263.15 K and 268.15 K, respectively .In 24 h, thermal conductivity increases only 5.45% at 268.15 K, but thermal conductivity increases 196.29% at 263.15 K. Methane hydrates exhibit only minimal decomposition at 1 atm an d the temperature ranging from 263.15 K to 271.15 K. At 1 atm and 268.15 K, the total gas that evolved after 24 h was amounted to less than 0.71% of the originally stored gas, and this ultra-stability was maintained if the test was lasted for more than two hours before before terminating