Numerical study on the thermal-hydraulic characteristic of an automotive parallel-flow condenser under non-uniform airflow

The performance of an automotive parallel-flow condenser was numerically investigated considering both airside and refrigerant-side flow mal-distributions, the thermal-hydraulic characteristic of the condenser under the air-side blockage of each tube pass was first studied, then the influence of the form and degree of uneven airflow that may be revealed in vehicles on the performance of the condenser was analyzed. At last, using the simulation model combined with the measurements of the vehicle in the climatic wind tunnel, the thermal-hydraulic features of the condenser as well as the performance of the A/C system under various front-end status and vehicle conditions was evaluated. It was found that the performance degradation of the condenser resulting from the air-side blockage of the first pass exceeds that caused by the obstruction of all the other three passes together. According to the performance deterioration sequence of the condenser from high to low, the order of the four possible non-uniform airflow patterns in vehicles is low on the top and high at the bottom (LTHB), low in the middle (LM), high in the middle (HM), and high on the top and low at the bottom (HTLB), and the last two forms could even enhance the performance of the condenser under certain working conditions. The rule of cooling airflow optimization is to arrange large/small air velocity on the area with intrinsically large/small refrigerant side heat transfer coefficient of the condenser. The possible direction of cooling airflow design in vehicles is inferred.