MDE Unit 4 Q2

Air coolers, also known as charge air coolers or intercoolers, are installed after main engine turbochargers to increase engine efficiency and performance.

1. Charge Air Coolers Explained – Vestas aircoil

The reason for this is to reduce the temperature of the compressed air before it enters the engine’s combustion chambers.

Here’s why this is crucial:

• Denser air: Cooler air is denser than hotter air. This means that more oxygen molecules can be packed into the same volume of air.   1. Cold air is dense – Lamont-Doherty Earth Observatory www.ldeo.columbia.edu2. What is a Charge Air Cooler and Why Are They Important – Dura-Lite www.duralite.net
• Improved combustion: A denser air-fuel mixture burns more efficiently, producing more power and torque.   1. Air Density – The Key to Making Power official.bankspower.com
• Reduced engine knock: Cooler air reduces the likelihood of engine knock (detonation), which can damage the engine.
• Lower emissions: More efficient combustion leads to reduced emissions.

By cooling the compressed air, the air cooler significantly enhances the performance and efficiency of the turbocharged engine.  

1. What is a Charge Air Cooler? | Integrated Engineering

While it might seem counterintuitive, undercooling the charge air can have negative consequences for the engine:

Reduced Engine Performance:

• Increased air density: Excessively cold air can lead to increased air density, which can cause higher peak cylinder pressures. This can result in increased mechanical stress on engine components.
• Detonation: Higher cylinder pressures can increase the risk of detonation (engine knocking), which can damage engine components.
• Increased friction: Colder air can lead to increased friction between piston rings and cylinder walls, potentially leading to premature wear.

Other Issues:

• Lubrication problems: Extremely cold intake air can affect the engine oil’s ability to form a protective film on cylinder walls, potentially leading to increased wear.
• Increased emissions: While undercooling might initially seem to reduce emissions due to denser air, it can actually lead to increased emissions under certain operating conditions.

It’s important to note that the optimal charge air temperature is a balance between maximizing engine performance and preventing potential issues. Overcooling, just like over-heating, can be detrimental to the engine.