110525 wb3110 ED combustion engines - TU Delft OCW • Compression and expansion in the cylinder...

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Transcript of 110525 wb3110 ED combustion engines - TU Delft OCW • Compression and expansion in the cylinder...

  • 1

    31-5-2011

    Challenge the future

    Delft University of Technology

    wb3110 Combustion Engines Evolving design in marine propulsion

    Dr. Hugo Grimmelius

    2Evolving Design: Dieselmotoren

    1. Introduction: history

    3Evolving Design: Dieselmotoren

    Tijdschaal

    • Eind 1600 eerste experimenten met stoom • 1816 het stirling principe • 1880 eerste gasmotor. • 1886 Otto motor op benzine • 1892 Diesel zelfontbranding • 1957 Wankelmotor

  • 2

    4Evolving Design: Dieselmotoren

    Geschiedenis lesje…

    5Evolving Design: Dieselmotoren

    2. “Grote diesels”

    6Evolving Design: Dieselmotoren

  • 3

    7Evolving Design: Dieselmotoren

    Slow speed engine (2 stroke)

    8Evolving Design: Dieselmotoren

    8

    Medium speed engine (line)

    9Evolving Design: Dieselmotoren

    9

    Medium speed engine (V)

  • 4

    10Evolving Design: Dieselmotoren

    High speed diesel engine

    11Evolving Design: Dieselmotoren

    11

    12Evolving Design: Dieselmotoren

    12

  • 5

    13Evolving Design: Dieselmotoren

    13

    14Evolving Design: Dieselmotoren

    3. Theorie

    15Evolving Design: Dieselmotoren

    Cilinder geometrie

    TDCV

    VBDC

    TDC

    BDC

    SLStroke:

    BDBore:

    S 2

    B

    SBS

    LD 4

    LAV

    ⋅⋅π=

    ⋅= Stroke volume:

    TDC

    BDC

    V V=ε

    Geometrical compression ratio:B

    S S D

    L=λ Stroke-bore

    ratio

  • 6

    16Evolving Design: Dieselmotoren

    4-takt principe

    rotation

    crank

    piston

    exhaust valveinlet valve

    cylinder

    connecting rod

    fuel injector

    DA B C

    17Evolving Design: Dieselmotoren

    2-takt principe

    inlet port

    DA B C

    piston rod

    crosshead

    connecting rod

    piston

    fuel injector

    exhaust valve

    cylinder

    crank

    rotation

    18Evolving Design: Dieselmotoren

    Scavenging

    A B

    "Uni-flow" scavenging "Loop" scavenging

  • 7

    19Evolving Design: Dieselmotoren

    p-V diagram

    6 1

    5

    2

    3 4

    V

    VSVTDC

    p

    VBDC

    V

    VSVTDC VBDC

    2

    3 4

    5

    6

    1

    p

    A) 4-stroke cycle B) 2-stroke cycle

    20Evolving Design: Dieselmotoren

    Standard air cycles

    • Closed cycle • Combustion: external heat input • Perfect gas:

    • All processes internally reversible • Compression and expansion isentropic, i.e. reversible and en

    adiabatic, so Poisson applicable:

    • Expansion ends in same point where compression starts

    p V m R T⋅ = ⋅ ⋅ pc constant=

    v pc c -R constant= =

    1T V constantκ−⋅ =

    p V constantκ⋅ = p

    v

    c c

    constantκ = =

    21Evolving Design: Dieselmotoren

    Otto cycle

    p

    v

    T

    s

    s=c

    s=c

    v=c

    v= c

    2

    3

    4

    1 1

    2

    3

    4

  • 8

    22Evolving Design: Dieselmotoren

    Diesel cycle

    1

    2 3

    4

    1

    2

    3

    4

    s = c

    s=c

    p= c

    v= c

    p

    v s

    T

    23Evolving Design: Dieselmotoren

    Seiliger (dual) cycle

    2

    3 4

    5

    1 1

    2

    3

    4

    5

    T

    sv

    p

    s=c

    v= c

    v= c

    p= c

    s=c

    24Evolving Design: Dieselmotoren

    Turbo charger

    Exhaust Receiverexh

    Principle of turbocharging

    Cylinders

    inlInletReceiver

    Charge Air Compressor

    Inlet Filter

    IC Intercooler

    Exhaust Gas Turbine

    Exhaust Silencer

  • 9

    25Evolving Design: Dieselmotoren

    Limits in engine characteristic

    max rpm

    Min power

    Engine speed (rpm)

    Engine power (kW)

    Max power

    min rpm

    26Evolving Design: Dieselmotoren

    Real envelope natural aspirating engine

    PB

    ne,min ne,max ne

    MB

    ne,min ne,max ne

    27Evolving Design: Dieselmotoren

    Real engine envelopes

  • 10

    28Evolving Design: Dieselmotoren

    Principle of indicated work

    BDC

    TDC

    V

    exp exp V

    W p dV= ⋅∫Expansion stroke delivers work:

    TDC

    BDC

    V

    comp comp V

    W p dV= ⋅∫Compressions stroke requires work:

    i exp comp cycle

    W W W p dV= + = ⋅∫

    Total indicated work is net sum:

    < 0 (since dV

  • 11

    31Evolving Design: Dieselmotoren

    Connection with brake power

    en if k ⋅

    =

    Firing frequency:

    P W fB e= ⋅

    Power is work per second:

    e S

    i nV V k ⋅

    = ⋅ recognize nominal volume flow

    through engine So mean effective pressure is

    specific power of a volumetric machine

    B me

    e S

    Pp k i n V

    = ⋅ ⋅ ⋅

    def e e

    B e me S n i n iP W p V

    k k ⋅ ⋅= ⋅ = ⋅ ⋅

    p W Vme

    def e

    S

    =

    32Evolving Design: Dieselmotoren

    Connection with brake torque

    B me

    e S

    Pp k i n V

    = ⋅ ⋅ ⋅

    def

    B B eP M 2 n= ⋅ π⋅

    Power is torque times speed

    So mean effective pressure is torque scaled with total swept volume

    B me

    S

    Mp 2 k i V

    = π⋅ ⋅ ⋅

    33Evolving Design: Dieselmotoren

    Power density

    Cluster the formula for mean effective pressure as follows:

    S

    B

    e me Vi

    P n kp

    ⋅ ⋅=

    Then power related to total engine cylinder displacement is:

    B VS

    S

    P i V

    β = ⋅

    Conclusion for high power density: - High speed

    - High mean effective pressure - 2-stroke instead of 4-stroke !!?

    me e VS

    p n k ⋅

    β =

  • 12

    34Evolving Design: Dieselmotoren

    Trend of power / stroke volume as function of nominal speed

    Specific power related to swept volume

    0

    10

    20

    30

    40

    50

    0 400 800 1200 1600 2000 2400

    Nominal engine speed in rpm

    Po w

    er /c

    yl v

    ol in

    k W

    /lt r

    High speed 4-stroke V-engines

    High/medium speed 4-stroke Line-engines

    High/medium speed 4-stroke V-engines

    Medium speed 4-stroke Line-engines

    Medium speed 4-stroke V-engines

    Low speed 2-stroke Line engines

    35Evolving Design: Dieselmotoren

    Trend of weight specific power as function of nominal speed

    Weight specific power

    0.000

    0.100

    0.200

    0.300

    0.400

    0.500

    0 400 800 1200 1600 2000 2400

    Nominal engine speed in rpm

    W ei

    gh t s

    pe ci

    fic p

    ow er

    M W

    /to n

    High speed 4-stroke V-engines

    High/medium speed 4-stroke Line-engines

    High/medium speed 4-stroke V-engines

    Medium speed 4-stroke Line-engines

    Medium speed 4-stroke V-engines

    Low speed 2-stroke Line engines

    36Evolving Design: Dieselmotoren

    Trend of volume specific power as function of nominal speed

    Volume specific power

    0.000

    0.100

    0.200

    0.300

    0.400

    0.500

    0 400 800 1200 1600 2000 2400

    Nominal engine speed in rpm

    Vo lu

    m e

    sp ec

    ifi c

    po w

    er M

    W /m

    3

    High speed 4-stroke V-engines

    High/medium speed 4-stroke Line-engines

    High/medium speed 4-stroke V-engines

    Medium speed 4-stroke Line-engines

    Medium speed 4-stroke V-engines

    Low speed 2-stroke Line engines

  • 13

    37Evolving Design: Dieselmotoren

    Bore area & mean piston speed

    Cluster the formula for mean effective pressure as follows:

    B

    B

    Se me Ai

    P Ln

    kp ⋅

    ⋅ ⋅

    = with: V L AS S B= ⋅

    mme cp ⋅

    “Technology”Introduce mean piston speed:

    def S

    m

    e

    2 Lc 1

    n

    distance time

    ⋅ = = ⇒ m e S

    c 2 n L= ⋅ ⋅

    Low speed 2-stroke: approx. 8 m/s Medium and high speed 4-stroke: 9 –12 m/s

    Then power related to total engine bore area is:

    k Lnp

    Ai P Seme

    B

    B AB

    ⋅⋅= ⋅

    =β k2 cp mme

    AB ⋅ ⋅=β

    38Evolving Design: Dieselmotoren

    Trend of technology parameter

    Technology parameter Diesel Engines

    0

    100

    200

    300

    400

    0 400 800 1200 1600 2000 2400

    Nominal engine speed in rpm

    Te ch

    no lo

    gy : p

    e* cm

    in b

    ar *

    m /s

    High speed 4-stroke V-engines

    High/medium speed 4-stroke Line-engines

    High/medium speed 4-stroke V-engin