Development of the Defrost Performance Evaluation Technology in Automotive Using Design Optimization Analysis Method

In this study, we developed the defrost performance evaluation technology using the multi-objective optimization method based on the CFD. The defrosting is one of the key factors to ensure the drivers’ safety using the forced flow having proper temperature from HVAC during drive. There are many factors affecting the defrost performance, but the configurations of guide-vane and discharge angles in the center DEF(defrosting) duct section which are main design factors of the defrost performance in automotive, so these were set to the design parameters for this study. For the shape-optimization study, the discharge mass flow rate from the HVAC which is transferred to the windshield and the discharge areas in the center defrost duct were set to the response parameters. And then, the standard deviation value of mass flow rate on the selected discharge areas checking the uniformity of discharge flow was set to the objective function to find the optimal design. The results on the windshield from optimization analysis were quantified from some kind of standards to evaluate the defrost performance, in particular, the important parts on it to secure the drivers’ safety as specified FMVSS103, to which the weighted value has been assigned. From this process, it is possible to quantify the defrost performance with various automotive models, and to find the optimized design. In case of using these methods, it is possible to reduce the calculation time, and to effectively analyze the results by controlling the design parameters systematically. These methods also make it possible to check the performance rapidly, and to propose the optimal design through the analytical verifications at the initial design stage.