Sang Youp Hwang

In this study, a feasible experiment on adsorbed natural gas (ANG) was performed using activated carbons (ACs) with high surface areas. Upgraded ACs were prepared using chemical activation with potassium hydroxide, and were then applied as adsorbents for methane (CH₄) storage. This study had three principal objectives: (i) upgrade ACs with high surface areas; (ii) evaluate the factors regulating CH₄ adsorption capacity; and (iii) assess discharge conditions for the delivery of CH₄. The results showed that upgraded ACs with surface areas of 3052 m²/g had the highest CH₄ storage capacity (0.32 g-CH₄/g-ACs at 3.5 MPa), which was over two times higher than the surface area and storage capacity of low-grade ACs (surface area = 1152 m²/g, 0.10 g-CH₄/g-ACs). Among the factors such as surface area, packing density, and heat of adsorption in the ANG system, the heat of adsorption played an important role in controlling CH₄ adsorption. The released heat also affected the CH₄ storage and enhanced available applications. During the discharge of gas from the ANG system, the residual amount of CH₄ increased as the temperature decreased. The amount of delivered gas was confirmed using different evacuation flow rates at 0.4 MPa, and the highest efficiency of delivery was 98% at 0.1 L/min. The results of this research strongly suggested that the heat of adsorption should be controlled by both recharging and discharging processes to prevent rapid temperature change in the adsorbent bed.