Seminar on Fpe

8/6/2019 Seminar on Fpe

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SEMINAR ON

FREE PISTON ENGINEGuided By, By,

wazzim MENISH S

7333

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FREE PISTON ENGINE

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INTRODUCTION

It is a linear , crank less internalcombustion engine.

The piston movement is not controlled bycrankshaft but determined by theinteraction of forces in the combustionchamber gases , a rebound device and aload device.

In 1807, de Rivaz tested an early engine thatoperated a free piston on a chain.

The modern free piston engine wasproposed by R.P. Pescara.

It is in practice restricted to two strokeoperating principle. 3


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INTRODUCTION [CONTD]

The piston is free because its motion is not

restricted by the position of the rotating

crankshaft.

Some of the distinct characteristics areVariable stroke length

The need for active control of piston

motion

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INTERNAL COMBUSTION

ENGINE

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TYPES OF FREE PISTON

ENGINES

Single piston

Double piston

Opposed piston

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SINGLE PISTON

It consists of three parts a combustion

cylinder, a load device and a rebound

device.

High controllability is the main strength ofthe single piston engine.

The rebound device give the opportunity to

accurately control the amount of energy

put in to the compression process.

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DOUBLE PISTON

It eliminates the need for a rebound device.

The working piston provides the work to

drive the compression process in the other

cylinder. Simple and more compact device with high

power to weight ratio.

The control of piston motion in a particular

stroke length and compression ratio isdifficult.

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OPPOSED PISTON

It consists of two single piston units with

common combustion chamber.

Each piston requires a rebound device and

a load device may be coupled to one or bothof the pistons.

Perfectly balanced and vibration free

design.

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OPPOSED PISTON [CONTD]

Reduced heat transfer losses due to the

opposed piston cylinder

It allows uniflow scavenging to be used,

giving high scavenging efficiency. Need of piston synchronization is the

important disadvantage of it.

It is complicated and bulky

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FIRST GENERATION FREE

PISTON ENGINES

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Air compressors

Gas generators


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AIR COMPRESSOR

Air compressor cylinders where coupled to

the moving parts , often in a multi stage

configuration.

Some of the engines utilize the airremaining in the compressor cylinder to

return the piston , thereby eliminating the

need of rebound device.

It had the advantage of high efficiency,

compactness and low noise and vibration.

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GAS GENERATORS

These are free piston engines feeding hot

gas to a power turbine.

The only load for the engine itself is that to

supercharge the intake air, the output workis taken out entirely from the power

turbine.

High compression and pressure ratio.

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MODERN APPLICATIONS

Hydraulic free piston engine.

Free piston engine generators.

Off highway vehicles.

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ADVANTAGES

Optimized combustion through variable

compression ratio.

Higher part load efficiency and possible

multi fuel operation. Reduced frictional losses.

Compact engine with low maintenance cost.

Enhanced fuel air mixing, reduction in the

time available for heat transfer losses andformation of temperature dependent

emissions such as nitrogen oxides.

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DISADVANTAGES

The main challenge for the free piston

engine is the engine control.

Misfiring .

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CONCLUSION

It is a crank less engine having higher part

load efficiency and variable compression

ratio.

More research is required to investigate thepotential advantages over conventional

technology.

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REFERENCES

R. Mikalsen , A.P. Roskilly . A review of

free piston engine history and applications

Wikipedia

M.L.Mathur , R.P.Sharma. a course inInternal combustion engines .

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Documents

Seminar on Fpe