(220c) Application of Multi-Element Structure Array On Activated Carbon Filter in HVAC Systems

Activated carbon is widely used in industries to remove gas phase contaminants such as ozone and volatile organic compounds (VOC). Coarse particles are mostly used in commercial carbon filters mainly due to their low flow resistance despite the fact that they have a low mass transfer rate which leads low bed utilization and short breakthrough times. In contrast, fine particles have higher mass transfer rate but are limited by high pressure drop. This study aims to improve the carbon filter to obtain a high carbon loading while maintaining a low pressure drop.  To reach this goal, a multi-element structure array (MESA), which combines multiple filters into single housing, was developed. A W-shape MESA bank can obtain a tenfold resistance reduction while introducing fourfold carbon load. A predictive pressure drop model for single honeycomb carbon filters, as well as MESA bank, was derived based on fundamental fluid dynamics equations and experimental data. The model can be used as a design tool to optimize carbon filter's parameter including filter depth, particle size, and filter count. Microfibrous entrapped sorbent (MFES) was prepared by entrapping fine particles (180-300µm) into 3D sinter-locked network of polymer or metal microfibers via a wet-lay process. These materials excel in mass transport and pressure drop due to their uniform structure with small particles and adjustable porosity. A polishing layer (a thin layer of MFES media placed in series with the packed bed) was used to improve the performance of bed by “polishing” the trace volume of gas after packed bed. Hexane adsorption breakthrough test was used to evaluate the performance of the composite bed based on the breakthrough time and percentage of adsorbent utilization. Experimental breakthrough curves showed that composite bed outperformed packed beds in single pass remove efficiency, breakthrough time and bed utilization due to a synergic effect between the high capacity of packed bed and the high contacting efficiency of MFES layer.