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CFD has been actively applied for developing automotive air conditioning system in recent years. In addition to automobile interior air conditioning, an automotive air conditioning system has the important function of providing a clear field of view by defogging (or defrosting) the windows. Although many CFD application methods have been reported for estimating windshield defogging pattern, few examples of simulation show accurate result of transient clearing pattern. To predict transient clearing pattern accurately, using a correct model of window glass fogging-clearing is important. As the result of our observation on fogged glass surfaces, fogging was found out to be an aggregation of water drops, so that new dropwise condensation-evaporation model was developed and applied. Transient defogging patterns were simulated with the CFD code including this model, and accuracy was verified on a simplified compartment model and actual automobiles.

To improve the performance of the air conditioning evaporator, we have Introduced unique refrigerant circuit. This circuit has refrigerant paths for both upstream and downstream air, and these paths are overlapped to provide uniform temperature distribution at the cooling air side. In addition, the fin pitch has also been minimized by establishing a drainage improvement technology. These technologies have made a great contribution to minimizing the core depth of evaporators.

The important problems to be tackled from the point of view of preventing global warming are to save the power consumption of car air conditioning systems and reducing the refrigerant used in those systems. Our approach to the task is to enhance system efficiency by utilizing sub-cooling at the outlet of the condenser and also to reduce the amount of refrigerant through a refrigerant behavior pattern analysis. This approach has created a simple system construction using an integrated condenser/receiver device.