An Assessment of the Operation Under Different Ambient Conditions of the Charge–Air Cooler for a Large Marine Diesel Engine

This study investigates the effect of ambient conditions, particularly the humidity of the intake air, on the operation of an ALCO V16 251F (USA) diesel engine. It evaluates the temperature at which air is delivered to the combustion chamber, after the cooling process is accomplished within the aftercooler heat exchanger. A theoretical analysis was conducted using AVL CRUISE software, a specialized computational tool developed by AVL that facilitates the simulation and virtual integration of engine subsystems. An experimental investigation on the operation of air coolers is difficult to perform on a test bench, due to the overall dimensions of heat exchangers used in large marine diesel engines. The simulation results show that the AVL CRUISE virtual cooler reproduces the temperature range of the ALCO aftercooler with small deviations of approximately 7% at the fluid outlets. In these conditions, simulation outcomes demonstrate that the engine’s original charge-air cooler can maintain a stable and controlled air temperature at the intake manifold inlet. For an absolute air humidity of 5%, only minor variations (less than 1%) were registered in the outlet air temperature from the aftercooler, accompanied by 0.7% decrease in cooling effectiveness and 0.6% decrease in heat-exchanger efficiency. These findings confirm that the charge-air cooler operates reliably under humid marine conditions and that the virtual model is suitable for further optimization studies.