Strategies for Complete Expansion in I.C. Engine

P M V SubbaraoProfessor

Mechanical Engineering Department

Achieve Maximum Work Output….

In 2000, a new engine is born ...

Three cylinder 5-Stroke engine

Five Stroke Internal Combustion Engine : A new concept for internal combustion enginesby Gerhard Schmitz, St.Vith 2011, Belgium

The Five Stroke Cycle

The five-stroke cycle consists in the following steps:

1. Admission in the high pressure (HP) cylinder

2. Compression, followed by the ignition

3. First expansion of the burned gases

4. Second expansion of the burned gases

5. Exhausting of the burned gases.

Phase A : Intake in Hp Cylinder 1, Expansion in HP 2 & Exhaust in LP

Load Pressure Regulation of the 5-stroke cycle at 4000 rpm

Speed Vs Loading Pressure @ Max. Torque

Phase B : Compression + Combustion in HP 1, Expansion in LP & Transfer from HP 2

Explicit Numerical Integration

1

2,,,

,

1

11 ii

i

miximixmix

ii

mix

ivwimixii

ivi

mixiiRTm

d

dVp

R

CTTAh

CV

Rpp

For a crank rotation of

Intake Valve Lift Diagram

Work Consumed by compression Process

dVpW

CS

IVC

CS

IVC

dVpWW nogenncompressio

,

TDC

CS

TDC

CS

dVpWW genncompressio

,

d

dRTm

d

dVp

R

C

d

Q

d

Q

VC

R

d

dp mixmixmix

mix

vlossgen

v

mix21

1

In above Eq., the rate of the heat loss Qloss/dθ is expressed as:

wmixloss TThA

d

Q

The convective heat transfer coefficient is given by the Woschni model as 8.08.02.02.3 mixUpDh

Modeling of Combustion Process

coldIVCIVC

IVCmixdpmix pp

Vp

TVCsU ,

128.2

For combustion and expansion processes: C1=0.00324.

Dual Phase Combustion

LHVmQQQ fcombindp

ddpp m

d

m

dd

d

d

m

p

m

pp

p

pgen amQ

aamQ

ad

Q

expexp11

The rate of the heat input Qgen/dθ (heat release)can be modeled using a dual Weibe function

Magnitude & Location of Peak Pressure

Phase C : Combustion + Expansion in HP 1, Intake in HP2 & Exhaust from LP

Work Delivered during Expansion in HP Cylinder

dVpW

TVO

CE

TVO

CE

dVpWW cmansion

,exp

BDC

TVO

BDC

TVO

dvmpWW cvansion

,exp

CE

TDC

CE

TDC

dVpWW gencmansion

,,exp

Phase D : Transfer from HP 1, Intake in HP 2 & Expansion in LP

Valve Lift Diagrams

Work Delivered during Expansion in LP Cylinder

dVpW

BDC

TVO

BDC

TVO

dvmpWW cvansion

,exp

Pressure/Volume diagram of 5-stroke cycle at 4000 rpm

Pressure/Volume diagram of 5-stroke cycle at 4000 rpm

BSFC of the 4- and 5-stroke engines at 4000 rpm

Net Work distribution at full load (100%)

Frictional Losses : ~ 5%