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스테인리스 쿨링포그의 온도저감효과 검증을 위한 모델설계 및 실증 실험
김재경,강준석,김회진,Kim, Jaekyoung,Kang, Junsuk,Kim, Hoijin 한국환경과학회 2020 한국환경과학회지 Vol.29 No.6
According to a NASA Goddard Institute for Space Studies report, temperatures have risen by approximately 1℃ so far, based on temperatures recorded in 1880. The 2003 heatwave in Europe affected approximately 35,000 people across Europe. In this study, a cooling fog, which is used in smart cities, was designed to efficiently reduce the temperature during a heatwave and its pilot test results were interpreted. A model experiment of the cooling fog was conducted using a chamber, in which nano mist spray instruments and spray nozzles were installed. The designed cooling fog chamber model showed a temperature reduction of up to 13.8℃ for artificial pavement and up to 8.0℃ for green surfaces. However, this model was limited by constant wind speed in the experiment. Moreover, if the cooling fog is used when the wind speed is more than 3m/s in the active green zone, the temperature reduction felt by humans is expected to be even greater. As a second study, the effect of cooling fog on temperature reduction was analyzed by installing a pilot test inside the Land Housing Institute (LHI). The data gathered in this research can be useful for the study of heat reduction techniques in urban areas.
전산유체역학(CFD)을 활용한 치악산 자연휴양림의 산불 및 연기전파 모델 분석
김재경(Jaekyoung Kim),강준석(Junsuk Kang) 한국방재학회 2022 한국방재학회논문집 Vol.22 No.5
본 연구는 치악산 자연휴양림에서 산불의 확산 경로, 도달시간과 확산 양상을 분석하였다. 산지 지형으로 발생하는 유동장분석과 연소모델 생성을 위해, 전산유체역학(Computational Fluid Dynamics, CFD) 프로그램인 Simcenter STAR-CCM+를 활용하였다. 도메인의 크기는 16 km2로 생성하고, 제 1 캠핑장에서 발화가 시작되는 것을 가정하였다. 모델 격자는 약 600만 개가 생성되었으며, 시뮬레이션이 시작된 후 1시간 동안 온도와 연기의 전파를 분석했다. 시간에 따른 확산 경로 분석을 위해 Implicit Unsteady 해석과, 유동장 분석을 위해서 Molecular Diffusivity 기능을 사용하였다. 본 연구를 통해 도출되는 결과는 다음의 세 가지다. 1) 산불 확산은 풍향 및 산지 지형으로 인한 연돌효과의 영향을 받는다. 2) 캠핑장에서 서쪽 500 m 떨어진 지점까지 산불이확산되는데 소요 시간은 22분 가량이며, 평균 1,200 ℃ 이상의 높은 온도를 보였다. 3) 산불의 인화점(Ignition Point)과 발화점(Flash Point)의 차이에서 발생하는 산불과 연기의 확산 속도는 시간의 변화에 따라 더 빨라졌다. This study analyzed the arrival time and diffusion pattern of a wildfire at Chiak Mountain, Wonju, Korea. Simcenter STAR-CCM+, which is a computational fluid dynamics program, was used to analyze flow fields generated by mountain topography and to create a combustion model. The size of the area under study was 16 km², and ignition was conducted at the first campsite. Approximately six million mesh were generated. The temperature and propagation of soot were analyzed for 1 h after the simulation was started. Implicit unsteady analysis was used for time-dependent diffusion, and molecular diffusivity was used for flow field analysis. The results were as follows. 1) The spread of the wildfire was affected by the stack effect derived from the wind direction and mountain topography. 2) Approximately 22 min were required for the wildfire to spread from the campground to a western point 500 m away, and the average temperature was 1,200 ℃ or higher. 3) The spread of the wildfire and soot caused by the difference between the ignition and flash points of the wildfire became faster over time.
LIF 기법을 이용한 액막형 선회 분사기의 액막 분열특성 평가
양동욱(Donguk Yang),김재경(JaeKyoung Kim),김경남(Kyungnam Kim),김덕진(Duckjin Kim),이지근(Jeekeun Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
The spray and breakup characteristics of the liquid sheet type swirl injector were evaluated using Urea-SCR injector for heavy-duty diesel engine. The results from experiments was compared with the results of a Urea-SCR injector which is already commercialized. The spraying of the liquid was controlled by pulse width modulation modes, and then spray and breakup characteristics of them were analyzed according to the injection pressures by using the PDA, PIV and LIF technique. The injector shows that the spray angle was small and the SMD was large, but the breakup length was small and the spray velocity is fast.
Urea-SCR 시스템 적용을 위한 스월 인젝터의 분무특성
홍정구(Junggoo Hong),구건우(Kunwoo Ku),김성열(Sungryoul Kim),이충원(Choongwon Lee),강명권(Myungkweon Kang),김경남(Kyungnam Kim),김재경(Jaekyoung Kim) 한국자동차공학회 2011 한국자동차공학회 지부 학술대회 논문집 Vol.2011 No.4
In this study, a swirl hollow cone injector, which has a good atomization performance at the low injection pressure relatively, was designed to apply the Urea-SCR. In order to investigate the spray pattern and SMD of a swirl injector, the spray visualization was conducted by using the simple swirl injector, and the images of the axial of stance from the nozzle exit. The shape of the spray was converted from the hollow cone to solid cone along the distance from the injector exit. The spray angle is increased and the SMD is decreased with increasing injection pressure respectively.
Urea-SCR 시스템 적용을 위한 스월 인젝터의 분무특성
홍정구(Junggoo Hong),구건우(Kunwoo Ku),김성열(Sungyoul Kim),이충원(Choongwon Lee),강명권(Myungkweon Kang),김경남(Kyungnam Kim),김재경(Jaekyoung Kim) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.4
??In this study, a swirl hollow cone injector, which has a good atomization performance at the low injection pressure relatively, was designed to apply the Urea-SCR. In order to investigate the spray pattern and SMD of a swirl injector, the spray visualization was conducted by using the simple swirl injector, and the images of the spray cross-section were obtained from a sheet beam of Nd-Yag laser and CCD camera. The SMD of the swirl injector was measured with the axial of stance from the nozzle exit. The shape of the spray was converted from the hollow cone to solid cone along the distance from the injector exit. The spray angle is increased and the SMD is decreased with increasing injection pressure respectively.