Charge air cooler optimisation

A charge air cooler (CAC), also known as an intercooler or aftercooler, is a device used in internal combustion engines (both diesel and gasoline) to cool the compressed intake air before it enters the engine’s combustion chamber. The turbocharger or supercharger compresses the air, making it hot and less dense. The charge air cooler cools the compressed air by passing it through a heat exchanger, which uses air or liquid to remove heat from the compressed air. This results in denser, cooler air, leading to better combustion and increased engine power. In this study, Synergetics Consulting Engineers employed computational fluid dynamics (CFD) to model and then optimise the performance of a diesel locomotive charge air cooler unit.

Figure 1: An electric motor and fan inside the charge air cooler unit. The inlet to the charge air pipe is visible at the lower right-hand corner of the unit.

The team developed a numerical model of the complete system and validated it against experimental measurements provided by the manufacturer. Synergetics then tested a range of different fan, fuel cooler and louvre configurations to determine which configuration would provide optimal cooling performance. The manufacturer used these results to demonstrate that the air cooler unit would meet performance requirements under various operating conditions.

Figure 2: Streamlines and temperature contours inside the charge air cooler unit.