Clean Technology (청정기술)

The Korean Society of Clean Technology (한국청정기술학회)
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A Study on the Flow Uniformity and Characteristics of Exhaust gas in Diesel Particulate Filter/Diesel Oxidation Catalyst of Ship Diesel Reduction System by Computational Fluid Dynamics

CFD에 의한 선박용 DPF/DOC내 배기가스의 유동 균일도 및 특성 연구

  • Kim, YunJi (Department of Environment-Energy Engineering, The University of Suwon) ;
  • Han, Danbee (Department of Environment-Energy Engineering, The University of Suwon) ;
  • Baek, Youngsoon (Department of Environment-Energy Engineering, The University of Suwon)
  • 김윤지 (수원대학교 환경에너지공학과) ;
  • 한단비 (수원대학교 환경에너지공학과) ;
  • 백영순 (수원대학교 환경에너지공학과)
  • Received : 2019.05.20
  • Accepted : 2019.06.07
  • Published : 2019.06.30
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Abstract

As air pollution becomes more serious due to the increased number of diesel vessel operations, ship regulations on harmful emissions strengthen. Therefore, the development of a diesel exhaust after-treatment system for ships is required, and the higher the flow uniformity of the exhaust treatment system, the higher the treatment efficiency. With the computer software ANSYS Fluent, pressure drop and flow uniformity were used in this study to simulate flow rate with and without a baffle in both a Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF) system. The system pressure drop was found to be 38 to 40 mbar in the existing system condition, and the flow uniformity was approximately 84 to 92% at the inlet and outlet of the DOC. When the baffle was installed inside the system, the pressure increased and the flow uniformity was lowered due to an increase in flow rate. When the exhaust gas flow was reduced by 50% from $7,548kg\;h^{-1}$ to $3,772kg\;h^{-1}$, the flow uniformity at the inlet and outlet of the DOC increased by approximately 1 to 3% due to the low flow rate. In the case of DPF, the flow uniformity of exhaust gas was 98 to 99% because the uneven flow proceeded after uniformly flowing from the DOC.

디젤 선박 운행 횟수의 증가로 인한 대기오염이 심각해짐에 따라 선박의 유해배출가스에 대한 규제가 강화되고 있다. 따라서 선박용 디젤 배기 후처리 장치의 개발이 요구되고 배기 처리 장치는 유동 균일도가 높을수록 처리효율이 증가된다. 본 연구에서는 ANSYS Fluent를 이용하여 기존 저감장치, 저감장치 내부의 Baffle 설치시, 배기가스 유량에 따른 배압과 유동 균일도를 시뮬레이션 하였다. 기존 장치조건에서는 시스템 배압이 38 ~ 40 mbar로 나타났으며, 유동 균일도는 DOC 입구와 출구에서 약 84 ~ 92%로 나타났다. 시스템 내부에 Baffle을 설치한 경우 압력이 상승되고 유속 증가로 인해 유동 균일도가 낮아진다. 배기가스 유량을 $7,548kg\;h^{-1}$에서 $3,772kg\;h^{-1}$로 50% 감소했을 때, 낮은 유속에 의해 DOC 입구와 출구의 유동 균일도는 약 1 ~ 3% 증가했다. DPF의 경우 불균일한 유동이 DOC를 균일하게 거쳐 흐른 후 유입되기 때문에 유동 균일도가 98 ~ 99%로 높게 나타났다.

Keywords

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Figure 1. Configure (L) and Model (R) for the reduction system of exhaust gas.

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Figure 2. Pressure distribution for the reduction system of exhaust gas.

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Figure 3. Flow distribution for reduction system of exhaust gas.

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Figure 4. Geometry for the reduction system of exhaust gas with plate baffle.

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Figure 5. Flow velocity distribution of DOC with plate baffle.

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Figure 6. Baffle installation point in the system.

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Figure 7. Flow velocity distribution of DOC with Baffle ①.

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Figure 8. Flow velocity distribution of ② Baffle.

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Figure 9. Flow velocity distribution of ③ Baffle.

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Figure 10. DOC flow velocity distribution at mass flow rate of 5,661 kg h-1.

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Figure 11. DOC flow velocity distribution at mass flow rate of 3,774 kg h-1.

Table 1. Characteristics of exhaust gas

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Table 2. Average flow rate and pressure distribution with the position of DOC and DPF

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Table 3. Flow uniformity with the position of DOC and DPF

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Table 4. Flow uniformity and pressure distribution of DOC with plate baffle

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Table 5. Flow uniformity and pressure distribution of baffle ①

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Table 6. Flow uniformity and pressure distribution of ② Baffle

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Table 7. Flow uniformity and pressure distribution of ③ Baffle

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Table 8. DOC flow uniformity and Pressure distribution at mass flow rate of 5,661 kg h-1

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Table 9. DOC flow uniformity and Pressure distribution at mass flow rate of 3,774 kg h-1

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