Inside It: Reciprocating Engines
(Sources: Automotive Mechanics by Crouse and Anglin, Thermodynamics by Cengel and Boles.)
Air Standard Assumptions
Actual gas power cycles are complex. To reduce analysis we follow the air standard assumptions, which are:
Overview of Reciprocating Engines and Some Important Definitions
A reciprocating engine is basically a piston-cylinder device. It is quite verstile and has a wide range of applications. Eg. Automobiles, trucks, ships, light aircrafts, electric power generators etc.
The figure shows the basic components of a reciprocating engine.
#-Link-Snipped-#
Photo: #-Link-Snipped-#
The piston reciprocates in the cylinder between two points called TDC and BDC
TDC or Top Dead Center is the position of piston when it forms the smallest volume in the piston
BDC or Bottom Dead Center is the position of the piston when it forms the largest volume in the cylinder.
Distance moved by the piston from TDC to BDC or vice versa is called a Stroke.
Bore is the diameter of the piston.
The whole arrangement contains two valves.
Intake Valve - through this the air-fuel mixture enters the cylinder.
Exhaust Valve - combustion products are expelled through it.
Clearance Volume - The minimum volume formed in cylinder when piston is at TDC.
Displacement Volume - Volume displaced by piston as it moves between TDC and BDC.
Compression Ratio - rotio of maximum volume formed in the cylinder to minimum(clearance) volume.
Mean Effective Pressure - a fictitious pressure that, if acted on a cylinder during the entire power stroke, would produce the same amount of work as produced during the actual cycle.
Air Standard Assumptions
Actual gas power cycles are complex. To reduce analysis we follow the air standard assumptions, which are:
- Working fluid is air, it continuously circulates in a closed loop and behaves like an ideal gas.
- All processes in the cycle are internally reversible.
- Combustion is replaced by heat addition from an external source.
- Exhaust is replaced by heat rejection to an external source.
Overview of Reciprocating Engines and Some Important Definitions
A reciprocating engine is basically a piston-cylinder device. It is quite verstile and has a wide range of applications. Eg. Automobiles, trucks, ships, light aircrafts, electric power generators etc.
The figure shows the basic components of a reciprocating engine.
#-Link-Snipped-#
Photo: #-Link-Snipped-#
The piston reciprocates in the cylinder between two points called TDC and BDC
TDC or Top Dead Center is the position of piston when it forms the smallest volume in the piston
BDC or Bottom Dead Center is the position of the piston when it forms the largest volume in the cylinder.
Distance moved by the piston from TDC to BDC or vice versa is called a Stroke.
Bore is the diameter of the piston.
The whole arrangement contains two valves.
Intake Valve - through this the air-fuel mixture enters the cylinder.
Exhaust Valve - combustion products are expelled through it.
Clearance Volume - The minimum volume formed in cylinder when piston is at TDC.
Displacement Volume - Volume displaced by piston as it moves between TDC and BDC.
Compression Ratio - rotio of maximum volume formed in the cylinder to minimum(clearance) volume.
Mean Effective Pressure - a fictitious pressure that, if acted on a cylinder during the entire power stroke, would produce the same amount of work as produced during the actual cycle.
Replies
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raj87verma88I am sorry for the delay in updates but am not getting sufficient time and am having some problems with my PC. Will definitely complete this thread. By the way could we have more Inside It series threads in various sections of the forum? I request all members to start them in appropriate sections. -
ShrinkDWorldthansk for4 such nice information
I will pray to god so that you can get suffiecnt tyime to commpite this thraed
I requrest you plz use more images. they will expain easily -
hrishikI am trying to model an engine mathematically.Can anyone please help me with this?
I am working on a project in which I am trying to develop a mean value model of an IC(SI) engine.If possible please post links. -
raj87verma88I think you can find links yourself if you try searching on Google and/or Wolfram Alpha.
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hrishikI tried to,But can you please help me out with the computational implementation.When we get pm(dot) and rpm(dot),how do we integrate them.
You are reading an archived discussion.
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