Turbochargers and Insulation

In many of today's diesel and gas engines, one will find two ‘chargers’ that are engineered to boost engine efficiency. One ‘charger’ runs hot, the other cold, and both use removable insulation blankets. The two ‘chargers’ that Firwin is referring to are turbochargers and charge air coolers.

Turbochargers

The purpose of a turbocharger (usually referred to as turbo) is to increase the mass of air entering the engine to produce more power. Turbochargers make this possible by using an engine’s exhaust gas flow to power a turbine which drives a compressor, which in turn raises the air flow into the engine’s cylinders. If there is more air in the engine’s cylinders, then the air/fuel mix will be greater and the resulting horsepower will also be greater.

Courtesy 'How Stuff Works.com'

As they use the engine’s own exhaust gas to power the turbine positioned inside the turbo’s housing, turbochargers run hot. Combine this with the fact that the internal turbine can spin at speeds over 200,000 rpm, and the potential for even more heat increases. And heat is what is needed, as the greater the heat and resultant pressure of the exhaust, the faster the turbine will spin, and the more air gets forced into the engine’s cylinders by the compressor.

This heat does have consequences, however, for engine performance and safety. An exposed hot turbocharger can pose a hazard to personnel, as well as unfavorably affect heat sensitive components that are close. Also, increased heat can escalate stress on the piston rings, piston, cylinder liner and cylinder head of the engine.

While the air that exhausts from the compressor section of the turbo is not as hot as the exhaust, (as the compressor is taking in ambient air and not exhaust air), the act of compression causes the temperature of the air to rise (for a regular diesel engine, to around the 200 °C / 400 °F mark). As hot air is not as dense as cooler air, less air can be forced into the engine cylinders, which in turns restricts the effectiveness of the turbocharger. This is where Charge Air Coolers have a role to play.

Charge Air Coolers

Courtesy 'How Stuff Works.com'

The job of the ‘Charge Air Cooler’ also known as an ‘aftercooler’ or ‘intercooler’ is to trap the compressed air and cool it down before it goes into the engine. The resultant cooler air is denser, and therefore more air can be packed into the engine cylinders than could have been realized with the hot air coming out of the turbo compressor.

Removable Insulation Blankets - How They Help

For turbochargers, an appropriately designed removable insulation blanket fitted on top of the turbo ‘hot side’, helps to keep the hot side of the turbo hot, and the cool side cool. This allows the turbo to operate more efficiently. Adjacent components that might be impacted by the very hot ambient temperatures produced by an exposed turbocharger are also protected. Finally, there is the aspect of personnel safety – a turbocharger with a removable insulation blanket will protect people from accidently burning themselves on an otherwise hot engine part.

Firwin Insulation Blankets on engine manifold, turbo and exhaust piping

Firwin Turbocharger Cover

For charge air coolers, removable insulation blankets are chiefly found on the piping that leads from the turbo/compressor into the cooler/radiator. The cooler is probably at a bit of a distance from the turbo, and the piping, which can be over 200 °C / 400 °F for diesel applications (gas would be higher) can pose a risk to personnel if not correctly insulated. Covering these pipes with removable insulation blankets will take the outer touch temperature down to safe levels.

CAT C27 / C32 Charge Air System with insulation blankets. Note the large cooler system (large black fan) in the background.

This information has been sourced, reviewed and adapted from materials provided by Firwin Corporation.

For more information on this source, please visit Firwin Corporation.