the process of combustion in engines p m v subbarao professor mechanical engineering department...
TRANSCRIPT
The Process of Combustion in Engines
P M V SubbaraoProfessor
Mechanical Engineering Department
Creation of Right Environment for Digestion of
Diet …...
Events in Combustion Processes
• Pre-processing of fuel an air.
• The initiation & stabilization of reaction.
• Execution and completion of the reactions.
• Post reaction events.
Pre-processing of fuel & Air
Pre mixing of fuel and air No Pre mixing of fuel and air
Partial Pre mixing of fuel and air
Care for Occurrence of Combustion
• Occurrence of combustion in SI Engine : A Child Care Event.
• Occurrence of combustion in CI Engine: A Teen Care Event.
CI Engine SI Engine
Type of Fuel Vs Combustion Strategy
• Highly volatile with High self Ignition Temperature: Spark Ignition. Ignition after thorough mixing of air and fuel.
• Less Volatile with low self Ignition Temperature: Compression Ignition , Almost simultaneous mixing & Ignition.
Types of Digestion of Diet
• Artificial Perturbation of fuel-air Mixture.
– All pre-process should be completed before perturbation.
– Digestion succeeds all the preprocess.
– Pre-mixed digestion/combustion.
• Natural Perturbation of fuel-air Mixture.
– A degree of pre-processing initiates the perturbation.
– However, pre-processes are accelerated during perturbation.
– Pre-process continue till the end of digestion.
– Simultaneous/Diffusive digestion/combustion.
What is the impact of combustion strategy on cycle area?
What needs to be studied to judge the suitability of a given strategy???
Gross Thermal Energy release in an Engine
• m number of reactants convert into n number of products, in order to release the required heat in an engine cycle.
• True available air will influence the number and quantity of products.
• The fraction of fuel chemical energy available to the cycle from actual combustion is quantified using combustion efficiency.
• The Gross chemical energy release due to actual combustion with in the engine is:
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