Charge air inter cooler



 Inside this post
  • Intercooler Introduction
  • How it works
  • Heat transfer calculation
  • Problems
  •  Treatment precess


Charge air inter cooler used to cool charging air coming from compressor unit of Turbo Charger.Charge air coolers are located between the turbo charger and the engine air inlet manifold. When the air is compressed by the turbocharger or supercharger, it is also heated, which causes its density to decrease.
MAN B&W interclloer
MAN B&W intercooler


Cooling the combustion air by a charge air cooler prior to sending it into the engine, the density of the air increases which permits more air to enter the engine and increases the power and efficiency of the engine..For proper combustion of fuel,it is required to maintain charge air temperature to a certain limit.(For MAN B&W 9L 58/64 engine the range is 45-55 degree Celsius).

How it works?

Hot air coming from the turbocharger(compressor unit) flows through air passage inside the intercooler. The turbocharger air transfers heat to the tubes, warming the tubes and cooling the turbo air. Outside water passes over the tubes. Heat is transferred from the hot air to cool water occurs. This is how the turbocharger air is cooled down.

The theoretical heat transfer occur

The amount of heat transfer occur between two fluids(air and water) can be calculated from the following equation,
                      Q = m x Cp x dT

Q =is the energy transferred.

m= is the mass flowrate (lbs/minute) of fluid
Cp =is the heat capacity of the air. It is about 0.25 for air and 1.0 for water.  .
dT= is the difference in temperature between the inlet and outlet. 


Intercooler Materials 
       
Tube
Tubes
  • Aluminium (Light Weight)
  • Aluminum-Brass alloy
  • Copper
  • Nikel 
  • Mild steel(cheap)
  • Stainless steel (heavy duty)
  • Aluminium tube with Zinc Sprayed(corrosion resistant)
Fin
Fins
  • Usually Aluminium(temperatures lower than 150°C)
  • Aluminium alloy
  • Copper( for over 150°C charge air temperature)
  • Tin Plated Copper( for over 150°C charge air temperature)
    Frame
    For applications, carbon steel and Rolled Naval Brass are widely used materials for side panels and middle mirrors respectively. Stainless steel can also be used for applications if desired. The construction must be well designed for the robustness and resistance to vibration of the unit.

    Intercooler Problems
    • Low heat transfer rate-Due to scale formation in tubes and fins external and internal surface
    • Leakage in tubes-Due to corrosion or life time get over 

    Corrosion in fins
    Fins get staked
    • Fins get staked together-Due to excess pressure
    • Corrosion in fins
    • Structural damage-Due to external pressure
    Treatment Precess 

    Treatment process consist of few steps.
    • Removing dust,Carbon deposits and other impurities with the help of compressed air
    • Submerging the cooler in Chemical mixed water
    "If the condition become very bad then pour degreaseer on the cooler and keep it in dry state 4 ti 5 hours" 
    • Attached heater and maintain the temperature about 45 degree celsius
    • Provide compressed air line under the cooler
    • Keep in this condition about 12 hours(sometime vary)
    • Draw it from water and spray normal water until all the impurities gone
    • Provide compressed air to remove water particle from the cooler
    "During compressed air and water spraying, always spray such a way that fins are not bended"


     
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