The effect of charge air condensate on Diesel Engine

The effect of charge air condensate on Diesel Engine is massive. The formation of charge air condensate depends upon many factors. The relative humidity of the air and cooling system (CHATCO) play an important role for condensation. If the formation of charge air condensation is not controlled properly, it creates huge impacts on engine. Let’s discuss.

Cold corrosion inside combustion chamber

Fuel (Heavy fuel oil) contains Sulphur. Charge air contains water in vaporized form. During engine stopped condition, as the combustion chamber temperate goes down (below dew point temperature), water forms as a film onto the component's surface of as aerosols. 

Corrosion inside combustion chamber due to condensation

This water combines with sulphur and form sulphuric acid, which causes cold corrosion in the combustion chamber components (Cylinder liner, piston crown, cylinder head, exhaust- inlet valves & seats.

Channel on Inlet valve and valve seat sealing area

Due to the acid formation in the inlet valve and valve sealing surface, corrosion started and the material properties changed (getting weak). Experience shows that the sulfuric acid corrodes the softer phases of the cast iron at a faster rate. 

valve and valve seat damaged due to charge air condensation

During suction stroke charge air (saturated with fine water particle) and condensate entered through the sealing surface which acts as jet and damaged the weak area. As the sealing surface starting damaged, exhaust gas also damaged the surface.

Torched valve sealing surfaces showed metal loss, surface cracking, and oxidation. Non torched areas retained a compacted oil deposit covering an oxidized sealing surface.

Intake manifold corrosion

 High condensate in the charge air causes corrosion (rust formation) in the intake air manifold. Charge air strike at the wall and the end cover and goes to liquid form. Not all condensate drained at a time. Some go to combustion chamber and some stayed in the bottom of the charge air manifold which cause corrosion.

Corrosion inside charge air manifold due to condensate

Charge air cooler corrosion

 After charge air cools down in the charge air cooler condensate forms and goes down for drainage. If the humidity is high and the drainage system is not sufficient condensate water accumulated in the bottom side of the charge air cooler casing. Due to the condensate water in the bottom side of the inter-cooler cover and support frame gets heavily rusted.

Rusty Charge Air Cooler due to Condensate

High exhaust temperature

 Due to water content in the charge air the air fuel ratio (oxygen in the air) does not remain balanced for complete combustion. So, some unburnt fuel burnt gradually in the expansion and exhaust stroke and the exhaust gas temperature get high.

High fuel consumption

Charge air contains moisture, which reduces combustion speed.

Combustion efficiency is always higher at low condensate in charge air. This has a positive relationship with fuel consumption and negative relationships with combustion efficiency.

Conclusion: humidity as low as possible for better fuel consumption and higher efficiency