Impacts of non-uniform airflow over gas cooler on the performance of transcritical CO2 air conditioning

Abstract

The air flowrate and air inlet temperature over gas cooler in transcritical CO₂ air conditioning for vehicles are easily unevenly distributed due to the influence of upstream obstacles. The unevenly distributed airflow affects heat exchange between CO₂ and air, thus influencing the cooling capacity and power consumption of the air conditioning system. This study delves into the implications of such non-uniform airflow on the operational performance of transcritical CO₂ air conditioning through simulation analysis. It elucidates the mechanisms by which the uneven distribution pattern, uneven distribution direction and non-uniformity affect the cooling capacity of transcritical CO₂ air conditioning system. Moreover, the conditions of inhomogeneous airflow for enhanced heat transfer are explored by decoupling inhomogeneous flow rate and inhomogeneous temperature. Results indicate that non-uniform airflow of air temperature distributed as TB-HT (high in top and low in bottom) and air flowrate as TB-HB (high in bottom and low in top) increases the cooling capacity of 27.7 % at non-uniformity of 55 %. Conversely, uneven airflow of flowrate and temperature both distributed as LR-HL (high in left and low in right) at 40 % non-uniformity leads to a wastage of compressor power up to 1/2. These findings reveal the dual impacts of non-uniform airflow on the performance of transcritical CO₂ air conditioning system, which emphasizes the importance of considering these impacts when designing automotive CO₂ air conditioning systems.