Session 5 - Oral 11
Rapid methane hydrate formation in open-cell copper foam
Jiajie Wanga,b, Liang Yanga,b,*, Xinxin Shaoa,b, Hao Zhanga,b
a School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
b Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, Shanghai 200093, China
ABSTRACT：Rapid formation of hydrate with high gas storage capacity is very important for the application of natural gas hydrates technology. Three pieces of open-cell copper foam (CF) with different pore density (or pores per inch, PPI) herein were immersed in sodium dodecyl sulfate (SDS) solution for enhancing methane storage in clathrate hydrates. The promotion effects of CF on the methane hydrate formation in the metal-filled systems were investigated via an unstirred tank reactor. Abundant micro holes and micro grooves are covering with the surface of CF skeleton, which can provide many metal nuclei for gas–water crystallization. The nest-like metal skeleton acts as crisscross “highway” for the crystallization heat transfer. The results demonstrated that methane hydrate was quickly formed in the SDS/CF systems, but CF with high pore density was not favorable for the conversion of water to hydrate. The SDS solutions with the high pore density CF (15, 30 PPI) were able to store more methane at a faster formation rate, compared with the system with the low pore density CF (5 PPI). However, the induction time of methane hydrate nucleation in 15 PPI CF was less than that in 30 PPI CF. A theoretical model based highly porous two-phase systems was used to predict the effective thermal conductivity (ETC) of the CF embedded with hydrate. It was found that the ETC of the hydrate/CF composite was significantly enhanced by using CF matrix, and the low pore density CF had a more positive impact on enhancing the ETC of the composite. Further comparative experiments conducted at various pressures indicated that the solutions containing 15 PPI CF exhibited higher methane storage capacities and lager hydration rates than the simple SDS solution, especially at the low pressure.
Keywords: methane hydrate, formation kinetics, thermal conductivity, copper foam