Numerical Modeling of Adsorption Dynamics through Activated-carbon-fiber Cloth

Activated-carbon-fiber cloth (ACFC) [ 1-5] has promising characteristics as an adsorbent, and potentially as a molecular sieve, a catalyst, or a catalyst support for a wide range of concentrations and chemical species. This is mainly because ACFC can be prepared with different and controlled pore size distributions, total pore volumes, specific surface areas and surface chemistries. ACFC can be > 95% by mass carbon, with the balance being hydrogen, oxygen, and nitrogen. Surfaces of ACFC can be modified to be acidic, basic, neutral or polar surfaces [6-7]. Risk of side reactions, poisoning and sintering in a zero ash content ACFC is minimal. Due to the ACFC physical structure and electrical resistance properties, it can be efficiently regenerated by electro-thermal regeneration [1,2,8]. Adsorbate retentivity in ACFC regenerated electro-thermally is less than in other carbon adsorbents regenerated by conventional methods. The high affinity of ACFC for certain adsorbates and rapid adsorption, desorption and heat transfer rates can reduce the required process cycle time, and increase the working capacity by reducing the length of the mass transfer zone. ACFC can be installed in different configurations providing desired heat, mass and momentum transfer. Therefore, use of ACFC in many new applications is promising for the near future. To take advantage of ACFC properties fully in the design of a separation, purification or catalytic conversion system, it is important to simulate transport processes through it. Simulation of these processes can be used to perform sensitivity studies that describe the performance of a proposed system. Results can then be used to fund the optimum process conditions for a certain objective such as reducing the cost. Because ACFC is inhomogeneous and has different degrees of periodicity and characteristic lengths in three dimensions, coupling of heat, mass, and momentum transfer processes affect the ACFC local adsorption equilibrium and kinetics. With recent advancements in computer hardware and computational algorithms, these complexities can be resolved to provide a general predictive tool.