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Numerical and experimental studies of thin liquid film flow between two forward-rollers
Chia-Hung Chien,Jiin-Yuh Jang 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.11
Roll coating is a widely used industrial technique to deposit a thin and uniform liquid film on a sheet or solid substrate.In this paper the three dimensional forward roll coating process has been studied by both experiments and numerical simulations. Experiments were conducted on a 2 roll coating system of pick up roll and application roll using two samples of 50% and 70% by weight aqueous glycerin solutions. The gap between the two rollers at nip was maintained at 100 microns. The coating film thickness and the distance of the film splitting point from the nip were measured during the experiments. The coating film thickness was determined for different speed ratios for both samples. 3D Numerical simulations for forward coating process have been carried out and the simulation results were verified were with experiments. They match very well, the error between them being 5% to 10%.
3-D NUMERICAL AND EXPERIMENTAL ANALYSIS FOR AIRFLOW WITHIN A PASSENGER COMPARTMENT
Chia-Hung Chien,Yung-Hsin Chen,Shih-Chieh Wu,Jiin-Yuh Jang 한국자동차공학회 2008 International journal of automotive technology Vol.9 No.4
People use cars so frequently that they always consider the air-conditioning, and thermal comfort of the driver and passenger when buying a new car. Therefore accurate simulation of the thermal performance of automobile air conditioners to improve human comfort has become increasingly important. In order to improve the thermal comfort of passengers, 3-D flow motion and thermal behavior within vehicles must be analyzed. In this paper, a numerical simulation was used to investigate thermal behavior in a vehicle. Because air temperature at an air vent is related to the cooling capacity of the air conditioner, the cooling capacity was calculated using ε -NTU (effective number of transfer unit) theoretical equations. Using the air temperature relationship between inlet and outlet vents as boundary conditions, a 3-D unsteady κ -ε turbulent model was used to give a transient analysis simulation of the temperature field and flow conditions in a vehicle’s passenger cabin. Cooling cycle analysis and conjugate heat transfer analysis at the inside surface of the cabin’s ceiling, floor and sides were also considered. The predicted temperature distributions in the vehicles passenger cabin were in good agreement with those obtained experimentally.