A turbocharger, colloquially known as a turbo, is a turbine-driven, forced induction device that increases an internal combustion engine's efficiency and power output by forcing extra compressed air into the combustion chamber.
Types of Turbocharging In Marine Engine
There are two types of turbocharging Constant pressure type and Pulse type turbocharging
Constant Pressure Type Turbocharging
> In this type of turbocharging, from each cylinder exhaust gas leads to common manifold, from the manifold it goes to the turbine at a constant pressure. When exhaust gases expand through the turbine nozzles and blade , the work is done by utilizing the heat of exhaust gas
> Exhaust space manifold must be large enough to accommodate exhaust gas from all the cylinders without any pressure rise
> Normally used in 2 stroke marine diesel engines
Pulse Type Turbocharging
> In this type of turbocharging, from each cylinder exhaust gas directly leads to the turbine inlet, utilizing the pressure pulse or waves to do the work.
> When the exhaust valves open and exhaust gas blown through small piping to the turbocharger nozzles and blades, there the work done is by high velocity pressure pulses.
> Normally used in 4 stroke engines
Advantages of Pulse type turbocharging
> Good performance of frequent load change
> Good turbine acceleration at startup
> No additional blowers required
> No exhaust manifold required
Disadvantages of Pulse type turbocharging
You can answer following questions
> Exhaust space manifold must be large enough to accommodate exhaust gas from all the cylinders without any pressure rise
> Normally used in 2 stroke marine diesel engines
Must Read:> Types of turbochargers in marine diesel engines
Advantages of Constant pressure type turbocharging
> Good performance at constant load
> Due to the constant flow of exhaust, turbine efficiency is good
> No grouping required
Disadvantages of Constant type turbocharging
> Not good if continuous load fluctuation persists
> Requires additional blowers at startup
> Need big manifold to accommodate exhaust gas
> In this type of turbocharging, from each cylinder exhaust gas directly leads to the turbine inlet, utilizing the pressure pulse or waves to do the work.
> When the exhaust valves open and exhaust gas blown through small piping to the turbocharger nozzles and blades, there the work done is by high velocity pressure pulses.
> Normally used in 4 stroke engines
Advantages of Pulse type turbocharging
> Good performance of frequent load change
> Good turbine acceleration at startup
> No additional blowers required
> No exhaust manifold required
Disadvantages of Pulse type turbocharging
> Complicated Exhaust piping
> Exhaust grouping required
> Chance of blow back and there by chance of low efficiency.
You can answer following questions
> Which turbocharging method is used in main engine? (Imp)
> Which turbocharger method is used in auxiliary engine? (Imp)