Experimental emulation of charge air cooler temperature and pressure on an engine dynamometer for air–fuel ratio optimization and pulsation reduction

This study presents an experimental investigation aimed at addressing charge air cooler (CAC) delta temperature variation and air pulsation issues encountered during final vehicle calibration on engine dynamometers. Conventional calibration setups typically employ customized water-cooled CAC systems, which often fail to replicate actual vehicle conditions, leading to discrepancies in pressure, temperature, and air-fuel ratio (AFR). To overcome this limitation, a novel air-to-air (A2A) CAC configuration incorporating a dynamically controlled airflow system using a variable frequency drive (VFD) and a closed-loop PID controller was implemented on the engine dynamometer. The proposed setup enables accurate emulation of vehicle charge air temperature and pressure conditions under both stationary and transient operating modes. Experimental results demonstrate a significant reduction in pressure drop from 10 kPa to 1.2 kPa and improved temperature control from 49 °C to 39 °C, resulting in an efficiency improvement of approximately 6-8% compared to conventional water-cooled systems. The optimized CAC performance contributes to improved air density, stable AFR, reduced air pulsation (pumping loss), and enhanced overall engine efficiency. The findings confirm that the proposed methodology effectively replicates real vehicle conditions on the dynamometer, thereby minimizing iterative calibration efforts, reducing development time and cost, and improving reliability in OEM calibration processes.