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Noise reduction of Automotive HVAC systems is a hard task because of the highly complicated and very sensitive turbulent flow in the blower fan unit. First, we identified the location of noise sources by the Sound Intensity (SI) method, then we investigated the flow pattern by the oil-mist method. As a result, two main noise generation mechanisms have been identified. One mechanism is generated by the interaction of the strong steady flow of air in the unit with the fan wheel, and the other is from the turbulent flow between the fan blades. Results: A new fan blade design was developed that had improved control of the turbulent flow, and which configuration caused a noise reduction of 2 dB-A over current blown fan systems.

The use of copper heat exchangers was the major trend in large transportation vehicles due to their satisfactory performance in severe conditions. However, heat exchangers made of aluminum for the heat exchanger part and glass-fiber reinforced modified polyamide resin for the coolant tank have been developed due to the demand for weight and cost reduction as well as productivity improvement. In the injection molding of these large tanks, warping is an engineering concern. Therefore, by analyzing the warping with the use of injection molding simulations, we have developed a production method that is capable of satisfying the dimensional requirements without any dimension correcting process.

These days the alignment of radiator and condenser in the vehicle front is the major trend. Due to this alignment, the radiator characteristics are one-sidedly affected by condenser radiating heat, which will cause deterioration in the engine cooling performance at high engine speed and high heat load vehicle operation when air conditioning (A/C) capacity becomes excess. Studies were made on the effects that condenser operation have on radiator characteristics. Results showed that controlling the condenser operation characteristics will provide improved A/C and engine cooling performance in the vehicle system. This paper will discuss the details of the above-mentioned analyses with focus on the vehicle characteristics of front engine, front drive (FF) vehicles and the results of vehicle proving tests.

The main function of automobile heat exchangers is to transfer residual heat from the engine to the open air so as to keep running the engine at its best condition. In order to efficiently transport heat from the heat exchanger to the air, extended surfaces (e.q., fins) are usually provided over the outer surface of the water tube in the heat exchanger. Moreover, many bent out plate louvers are manufactured on the fin safaces. In order to obtain higher rate of heat transmission in a more compact heat exchanger, many experimental and analytical studies have been carried out up to the present. However, there are many difficult problems to be resolved so far in finding the obtimum louver profile because of the complexity of air flow around small-scale louver assemblies. In the present paper, the characteristics of air flow as well as heat flow around louver assemblies are analysed by the numerical analysis code developed at the Central Engineering Laboratory of the Nissan Motor Co., Ltd.