When the turbocharger compresses the intake air, it usually raises the air temperature to 300°F (150°C) - this is the data under an ambient temperature of 70°F (21°C); if the ambient temperature is higher, the intake air temperature will increase accordingly. Regardless of the cooling medium used, the core goal of the intercooler is to cool the air that has been pressurized by the turbocharger. The key lies in minimizing the air temperature while maintaining pressure stability. As the intake air temperature rises, the air density decreases, and the oxygen content in the cylinder decreases, resulting in reduced engine power and increased cylinder temperature. The intercooler is essentially a heat exchange device specifically designed to cool the hot turbocharged intake air.
To minimize this potential power loss, the compressed air needs to be cooled through various heat exchangers. Generally, for every 1°C increase in intake air temperature, the exhaust temperature will rise by 2°C. It is worth noting that the performance of the intercooler directly affects the combustion temperature and the air density in the cylinder. It has become an indispensable component in the vehicle's harmful emissions control system. Currently, most turbocharged diesel engines use some type of heat exchanger to cool the intake air.
Types of intercoolers
For ease of study, we divide the turbocharger air coolers into the following categories:
• Air-to-air intercooler: The cooling medium is ram air.
• Post-cooler and intermediate intercooler: The cooling medium is a combination of engine coolant and ram air.
• Tip-rotor intercooler: The cooling medium is the airflow driven by the turbine fan that is cooled through the heat exchanger, sometimes supplemented by engine coolant.
The type of intercooler selected depends on the specific application of the vehicle. For example, the air-to-air intercooler has the highest efficiency, but due to its reliance on the vehicle maintaining a certain speed, it performs poorly in many engineering trucks or urban buses. Tip-rotor intercoolers have been gradually phased out in highway truck engines in recent years; they are still used in large off-road mobile diesel engines,