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자동차용 헤드램프 습기현상에 대한 플라스틱 발수해석 모델 개발
이재명(Jaemyeong Lee),노규철(Kyuchul Roh),유기수(Kisoo Yoo),배철호(Cheolho Bae),심재술(Jaesool Shim) 대한기계학회 2019 大韓機械學會論文集B Vol.43 No.7
본 연구의 목적은 자동차 헤드램프 습기 발생의 주요 요인 중 하나인 플라스틱 발수에 대한 해석모델을 개발하고 실험 결과와의 비교를 통해 해석정확도를 검증함에 있다. 발수 해석 모델은 절대 습도를 위해서 수분 수송 방정식을, 증발 및 응축을 위해서는 수막 방정식을 사용하였고, 실차 조건의 온도경계 조건을 모사하기 위해서 평균 온도 개념을 도입하여 수치 해석 모델을 단순화하였다. 플라스틱의 발수는 플럭스 경계조건을 사용하였다. 플라스틱 발수 플럭스는 칼피셔 장비로 측정한 결과를 토대로 아레니우스식의 형태로 표현하였다. 해석 결과는 평균 온도에 의한 평균 습도 값으로, 실험 결과는 특정 위치에서 측정한 값으로 사용하여 비교하였다. 그 결과, 헤드램프 내부절대습도가 급격히 떨어지는 시점, 즉 응축이 일어나는 시점이 해석과 실험에서 동일함을 확인하였다. The objective of this study is to develop a simulation model of polymer desorption under on-car experimental conditions, which is one of the main factors in condensation phenomena for automotive headlamp, and to verify its accuracy by comparison with experimental results. The numerical model is composed of the species transport equation for absolute humidity, and the water film thickness equation for evaporation and condensation. To apply the temperature boundary conditions on the walls inside the headlamp as the on-car test conditions, a time-dependent average temperature is utilized to simplify the numerical simulation. The Arrhenius type flux obtained using the Karl– Fischer Titration instrument is used for the polymer desorption on the headlamp walls for the species transport equation. The numerical average absolute humidity is compared with the experimental absolute humidity taken at a specific location. The results showed that the absolute humidity decreases sharply, i.e., when condensation occurs inside the headlamp, at the same time in the simulations and experiments.
이재명(Jaemyeong Lee),노규철(Kyuchul Roh),이충화(Choonghwa Lee) 한국자동차공학회 2018 한국자동차공학회 부문종합 학술대회 Vol.2018 No.6
Water desorption of polymeric materials in automotive headlamp are one of the main factor in condensation on the inside of the lenses. In this study, the method of measuring amount of water desorption was reviewed and measured amount of water desorption according to polymers by using KFT(Karl Fischer Titration). Setting standard temperature, the total amount of water desorption from parts in headlamp was predicted and compared real readings. And the causes of difference between prediction and measurement were analyzed in terms of KFT method.
조광운(Kwangwoon Cho),배종식(Jong Sik Bae),김학봉(Harkbong Kim),이재명(Jaemyeong Lee) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
On this study, fan less air cooling system that use air inflow naturally driven by the high pressure on the front head lamp during driving and the radiator fan during idle was developed for the LED head lamp. The tube and duct let the inflow air from the inlet grille on front of headlamp to be separated from the air head lamp inside. It makes sure not for contamination and fog up on lens of headlamp. The duct and heat sink were made of one aluminum body to increase the heat transfer area and the rubber tubes were flexible enough for the headlamp aiming movement. The hose connected to radiator fan shroud was 30mm diameter for suction during idle. As a result, the fan less air cooling system could cool the led lower then 102℃ during both idle condition and driving. It shows the new cooling system can make the led headlamp system cost down.