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Numerical Investigation of Droplets Condensation on a Windshield: Prediction of Fogging Behavior
Technical Paper
2015-01-0360
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
An accurate model to predict the formation of fogging and defogging which occurs for low windshield temperatures is helpful for designing the air-conditioning system in a car. Using a multiphase flow approach and additional user-defined functions within the commercial CFD-software STAR-CCM+, a model which is able to calculate the amount of water droplets on the windshield from condensation and which causes the fogging is set up. Different parameters like relative humidity, air temperature, mass flow rate and droplet distributions are considered. Because of the condition of the windshield's surface, the condensation occurs as tiny droplets with different sizes. The distribution of these very small droplets must be obtained to estimate numerically the heat transfer coefficient during the condensation process to predict the defogging time. This distribution is obtained in a preliminary experiment by using a camera mounted with a microscope on which the picture of the condensation on a windshield's sample is taken. The results show how the relative humidity, the air temperature, the velocity of the car and the droplet distribution influence the fogging pattern and the defogging time. Because of the uncertainties of the boundary conditions in this simple preliminary experiment with the microscope, a complete test bench is currently under investigation and real vehicle tests are planned.
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Leriche, M., Roessner, W., Reister, H., and Weigand, B., "Numerical Investigation of Droplets Condensation on a Windshield: Prediction of Fogging Behavior," SAE Technical Paper 2015-01-0360, 2015, https://doi.org/10.4271/2015-01-0360.Also In
References
- Hassan , M. , Petitjean , C. , Deffieux , J. , and Gilotte , P. Windshield Defogging Simulation with Comparison to Test Data SAE Technical Paper 1999-01-1202 1999 10.4271/1999-01-1202
- Kitada , M. , Asano , H. , Kataoka , T. , Hirayama , S. et al. Numerical Analysis of Transient Defogging Pattern on an Automobile SAE Technical Paper 2002-01-0223 2002 10.4271/2002-01-0223
- Croce , G. , D'Agaro , P. and Della Mora , F. Numerical simulation of glass fogging and defogging International Journal of Computational Fluid Dynamics, Rev. Jan. 2007
- Beysens D. Dew Nucleation and Growth C.R. Physique 7 2006 1082 1100
- Margrain Tom H. , Chris Owen The misting characteristics of spectacle lenses Ophthalmic and Physiological Optics 16 2 March 1996 108 114 0275-5408 10.1016/0275-5408(95)00023-2
- CD-adapco User Guide STAR-CCM+ version 9.02 2014
- Rose J.W. , Glicksman L.R. Dropwise condensation-The distribution of drop sizes International Journal of Heat and Mass Transfer 16 2 February 1973 411 425 0017-9310 10.1016/0017-9310(73)90068-9
- Leach , R. N. , Stevens , F. , Langford , S. C. , & Dickinson , J. T. Dropwise condensation: experiments and simulations of nucleation and growth of water drops in a cooling system Langmuir 22 21 8864 8872 2006 10.1021/la061901+
- Briscoe B.J. , Galvin K.P. The effect of surface fog on the transmittance of light, Solar Energy 46 4 1991 191 197 0038-092X 10.1016/0038-092X(91)90063-3