• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.529-534
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• 2003

Comprehensive study on the system, including blower and ducts, of HVAC device of a vehicle has been carried out for improvements of noise characteristics. The parameters of design improvements are concerned with geometric informations such as the shape of ducts and presence of a windshield window. Test results show that noise level increasing the following order: HV (HD) < V (D) < BH ${\sim}$ BHV (BHD) < B (B, H, V, D denote for blower, heater unit, vent duct, defrost duct, respectively). The effects of windshield glass on the noise level in the case of defrost mode are pronounced and the effects of the geometry of ducts on the overall HVAC noise prove to be not small.

• Journal of the Korean Society of Visualization
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• v.8 no.2
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• pp.40-44
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• 2010

Thermal comfort inside a passenger car has been receiving large attention in automobile industries. Especially, the performance of windshield defroster is important in the design of a car to ensure passenger comport and safety. Thereby, better understanding on the ventilation flow along the vehicle windshield is essential to evaluate the performance of windshield defroster. However, most previous studies dealt with the defrost flow using CFD (computational fluid dynamics) calculations or scale-down model experiments. In this study, a real commercial automobile was used to investigate the flow discharged from the vehicle defroster and the ventilation flow along the windshield using a PIV velocity field measurement technique. The experimental data would be useful to understand the flow characteristics in detail and also can be used to validate numerical predictions.

• International Journal of Automotive Technology
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• v.7 no.2
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• pp.139-143
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• 2006

As an automobile tends to be high grade, the needs for more luxurious interior and comfortable HVAC system are emerged. The defrosting ability is another major factor of the performances of HVAC system. The present work is to simulate the flow and the temperature field of cabin interior during the defrost mode. The three-dimensional incompressible Navier-Stokes equations and energy equation were solved on the multi blocked grid system by the iterative time marching method and AF scheme, respectively. The present computations were validated by the comparison of the temperature field of a driven cavity and velocity field of 1/5 model scale of an automobile. Generally good agreements were obtained. By the present computation, the complicated features of flow and temperature within the automotive cabin interior could be well understood.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.11
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• pp.1084-1091
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• 2004

In automotive air handling system, mixing of air streams by the cooler and the heater affects the comfort of cabin room. In the present study, computer-aided analysis is done to improve the thermal comfort and for the optimal design of automotive HVAC system. The simulation software used was FLUENT, and complicate geometries were created by three dimensional CAD. Air flow volume, fir distribution rate and temperature controllability and temperature differences between upper and lower discharge air are analyzed through numerical simulation at vent, floor and defrost mode. Also, velocity vector of sirocco fan is investigated through the scroll housing. The velocity vector magnitude is larger at lower region of fan than that at any other regions. Recirculation and disturbance of air is relatively high near the cut-off edge in the scroll housing. By using the results of this study, the time for prototype production can be reduced and timely decisions can be made to determine initial design directions.

• Journal of Energy Engineering
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• v.15 no.4 s.48
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• pp.235-242
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• 2006

This study experimentally investigates the performance improvement of the heat pump by adopting the hot gas bypass method and using the internal heat exchanger according to the automatic defrost test conditions of ISO 5151 This study compares the hot gas bypass method with the time step method, and investigates effect on outdoor coil fan speed when the hot gas of compressor outlet enter outdoor coil inlet after the frost formation. The tests were made for the fan speeds of the outdoor coil controlled at 90, 60 and 30% of the normal speed together with the case of the stationary fan. The performance of the heat pump is evaluated by variables such as COP, heat capacity, and the average COP during the 210 minutes heating mode. Results show that average COP of the hot gas bypass mettled is $2.2{\sim}6%$ higher than that of the time step method. When the outdoor coil fan speed is 60% (780 rpm) of the normal speed, it shows the best COP and heating capacity.