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Phung Quoc Huy 

Visiting PhD Student 
(June 30 - Sept. 20, 2009) 
with Kyushu University, Japan 

Research topic: Investigation of Volume Expansion of Coal Using Carbon Dioxide

CO2 sequestration into unmineable or depth coal seams is now being actively investigated as a method for reducing greenhouse gas emissions to the atmosphere. However, coal is well known to swell in the presence of CO2 and this is likely to affect gas transport through coal seams. It has been suggested that in situ coal swelling may close the cleat system in the seam thus reducing permeability. Swelling of coal may affect the accuracy of sorption capacity estimates because the volume of the coal may change during the measurement of the adsorption isotherms. We previously observed the volume change before and after CO2 gas adsorption process of Vietnam coal, the volume expansion amount were about 1.74~1.93% for the MK-V9D-1 coal sample [1]. In order to clarify the volume expansion phenomena, we designed a system to visually observe the volume change of coal samples when injecting CO2 (gas, liquid and supercritical). The result showed that the total area of sample increased around 1 to 5% after 40 hours sucked in CO2 super-critical. There are several CO2 droplets appeared on the surface of coal samples, the biggest droplet area was increased from 14% to 21% after 40 hours (see Figure 2 below).

Experimental system. 





The visualization results by using supercritical CO2 (T = 40 C; P = 7.5 MPa) 
LEFT FIGURE: After 22 hours, Ab = 0.028 sq cm, A = 0.365 sq cm 
MIDDLE FIGURE: After 24 hours, Ab = 0.032 sq cm, A = 0.370 sq cm 
RIGHT FIGURE: After 40 hours, Ab = 0.034 sq cm, A = 0.385 sq cm 
Ab: Area of CO2 droplet; A: Total area of coal sample. 




  1. Huy, P.Q., Sasaki, K., Sugai, Y., Ichikawa, S., and Babadagli, T.: “Visualization Study on Swelling of Coal Matrix in High Pressure CO2,” in the proceedings of Int. Symp. On Earth Science and Tech., Organized by Cooperative Int. Network for Earth Sci. and Tech. and Kyushu Univ., Dec. 8-9, 2009, pp. 6.

  2. Huy, P.Q., Sasaki, K., Sugai, Y. Kreangkrai, M., and Babadagli, T.: “Numerical Simulation of CO2 Enhanced Coal Bed Methane Recovery for a Vietnamese Coal Seam,” Journal of Novel Carbon Resource Sciences, vol. 2, 1-7, Sept. 2010.

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