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Sustainable reduction of the CO2 emissions of future vehicles goes hand in hand with the increase in efficiency of ancillary units. Of particular importance is the reduction of fuel consumption attributed to the vehicle's air conditioning system. The innovative development of a condenser with a 3-pass subcooling zone renders it possible to significantly increase the efficiency of the cooling circuit. This is applicable both in the case of current and future refrigerants. The basis for increasing the efficiency of the condenser is rooted in the systematic analysis of the local heat transfer functions, pressure drops and implementation of an improved flow path configuration. The current condenser design, which includes the functionality of a receiver/dryer with a dedicated subcooling zone, is effective at providing stable liquid refrigerant to the TXV under a variety of conditions.

The car air conditioning system causes approximately 0.5 l/100 km excess fuel consumption on average. To meet future fuel consumption and emission regulations improvements in the AC system are called for. To consistently assess improvements in air conditioning power consumption, specific driving and temperature profiles are defined. It is shown that improvements can be achieved by: Better thermodynamic component and system design Refrigerant expansion device sized for efficiency rather than maximum performance System control strategies such as variable air recirculation Measurement of a refrigerant circuit on a system test bench reveal that the energy requirement for A/C can by reduced by 15% to 30% compared to current state of the art AC system technologies. Only part of the presented measures are based on electronic controls however only the combination of all will lead to a significant reduction.