Analysis of a Gas Mask Using CFD Simulation

CFD모사기법을 이용한 가스 여과기 성능 해석

Abstract

Special chemical warfare agents are lethal gases that attack the human respiratory system. One of such gases are blood agents that react with the irons present in the electron transfer system of the human body. This reaction stops internal respiration and eventually causes death. The molecular sizes of these agents are smaller than the pores of an activated carbon, making chemical adsorption the only alternative method for removing them. In this study, we carried out a Computational Fluid Dynamics simulation by passing a blood agent: cyanogen chloride gas through an SG-1 gas mask canister developed by SG Safety Corporation. The adsorption bed consisted of a Silver-Zinc-Molybdenum-Triethylenediamine activated carbon impregnated with copper, silver, zinc and molybdenum ions. The kinetic analysis of the chemical adsorption was performed in accordance with the test procedure for the gas mask canister and was validated by the kinetic data obtained from experimental results. We predicted the dynamic behaviors of the main variables such as the pressure drop inside the canister and the amount of gas adsorbed by chemisorption. By using a granular packed bed instead of the Ergun equation that is used to model porous materials in Computational Fluid Dynamics, applicable results of the activated carbon were obtained. Dynamic simulations and flow analyses of the chemical adsorption with varying gas flow rates were also executed.

화학적 무기 중 혈액작용제는 전자전달계 내 효소의 철 이온과 반응하고 세포호흡을 정지시켜 사망을 초래한다. 혈액작용제는 활성탄의 미세공보다 분자크기가 작아 화학적 흡착이 유일한 제독방법이다. 본 연구는 SG 생활안전에서 개발한 SG-1 가스 여과기를 이용하여 혈액작용제 시아노겐 클로라이드(CK) 가스의 유입에 따른 유동해석을 수행하였다. 구리, 은, 아연 및 몰리브데늄 이온이 첨착된 ASZM TEDA 활성탄을 적용하여 가스 여과기 제작 시험 규정에 따라 화학적 흡착 모사를 수행하였으며 흡착 Kinetic을 적용하기 위해 선 수행된 흡착 베드에서 CK 가스 흡착 실험 결과를 분석하였다. 화학적 흡착을 통해 발생되는 가스 여과기 내부 압력강하 및 가스 흡착 질량 등 주요 변수의 동적거동을 예측하였다. CFD에서 다공성 물질을 적용할 때 사용하는 Ergun 방정식 대신 Granular와 Packed bed를 사용하여 활성탄 적용 가능 결과를 확인하였으며 시간에 따른 흡착 및 유속에 따른 흡착의 유동 해석에 대한 동적 모사를 수행하였다.

Fig. 1. CK gas adsorption experiment equipment.

Fig. 2. CK gas adsorption breakthrough curve.

Fig. 3. The amount of CK gas adsorbed according to the time in the adsorption bed.

Fig. 4. SG-1 gas mask geometry.

Fig. 5. CFD simulation framework with UDF.

Fig. 6. Simulation with different inlet flow rate (a) 0.04 m/s (b) 0.0947 m/s (c) 0.2 m/s.

Fig. 7. SG-1 gas mask internal velocity distribution (a) No activated carbon (b) Activated carbon.

Fig. 8. SG-1 gas mask internal pressure drop (a) No activated carbon (b) Activated carbon.

Fig. 9. Volume fraction of CK gas adsorbed at different simulation time.

Fig. 10. Amount CK gas adsorbed on activated carbon over time: mg.

Fig. 11. Velocity distribution for different inlet flow rate: (a) 0.04 m/s (b) 0.0947 m/s (c) 0.2 m/s.

Fig. 12. Pressure drop for different inlet flow rate: (a) 0.04 m/s (b) 0.0947 m/s (c) 0.2 m/s.

Fig. 13. CK gas volume fraction for different inlet flow rate: (a) 0.04 m/s (b) 0.0947 m/s (c) 0.2 m/s.

Table 1. Design conditions of SG-1 gas mask

Table 2. Simulation method for SG-1 gas mask

Table 3. Simulation condition of SG-1 gas mask

Table 4. Comparison of SG-1 gas mask simulation results with reference