Development of a simulation method to predict condensation outbreak in headlampsDevelopment of a simulation method to predict condensation outbreak in headlamps
Haibin TAN1, Jean-Charles KHOU2, Jiangkun LIU1, Guoliang XIE1 1, Valeo Lighting Systems China Technical Center B4 building, No.18 ShenLong Street, WEDZ, 430056 Wuhan, China 2, Valeo Lighting System 34 rue saint André Bobigny 93102 France Email: haibin.tan@valeo.com, jean-charles.khou@valeo.com, jiangkun.liu@valeo.com
Abstract-The issues regarding condensation apparition and clearance in headlamps are still a difficult topic to solve in warm and humid climate. In addition, the increasing amount of plastic components and complex designs in lighting products creates new challenges in regards to water desorption and venting systems management. In order to adapt to the different needs of automotive manufacturers, Valeo has developed a new method of simulation of condensation appearance to detect condensation risk with more precision. A simulation method for predicting defogging was formerly developed. The method can detect the critical condensed area and clearing trend, which correlated well with test. However, since reference products are used as a benchmark to compare the defogging performance, it doesn’t predict the exact transient condensation appearance and its properties. These information would yet be very valuable in order to design new and more efficient solutions to prevent or reduce condensation. This paper will present the condensation outbreak simulation method, which predicts the appearance of condensation, taking into account the water vapour desorption of specific plastic components and housing material as well as the transfer of moisture by convection and diffusion through different types of vents. A series of correlations have been performed in all kinds of automotive lamps, which show that simulations and tests results compare well. Based on these studies, absolute criteria regarding film thickness and surface coverage have been devised to characterize the visibility of condensation on headlamps. The data provided by these simulations are very helpful to better meet the specifications of customers, helping us finding alternative and innovative solutions to condensation issues. Keyword: Automotive headlamps, Condensation, Outbreak, Simulation, Vents, Humidity desorption. |