STUDIO DEI PROCESSI CHIMICO FISICI NEI MOTORI A COMBUSTIONE INTERNA

STUDIO DEI PROCESSI CHIMICO FISICI NEI MOTORI A COMBUSTIONE INTERNA

B. M. Vaglieco Istituto Motori – CNR Napoli, ITALY

[email protected]

The history

1940

2003

Studio dei fenomeni chimico fisici che avvengono nei motori a combustione interna per mezzo di tecniche ad

elevata risoluzione spaziale (< micron) e temporale (nanosecond)

Objective

Compression Ignition

Diesel Engine Gasoline Engine HCCI Engine Spark

Ignition

Homogeneous Charge Compression Ignition

Fuel injector

NO

soot

Spark plug

Flame front

NO

Hot Flame

Combustion

Studio dei fenomeni chimico fisici che avvengono nei motori a combustione interna per mezzo di tecniche ad

elevata risoluzione spaziale (< micron) e temporale (nanosecond)

Objective

Cat-DPF : 5.66”x6” SiC coated with CeO²+Pt

Engine 1: Multi cylinder diesel 1900 cm

UV Mirror Window High

pressure radial pump

Engine 2: Single cylinder

Injection Pressure

Sensor Optical

window Common Rail

Injection Pressure

Sensor Optical

window Common Rail

Engine 3: External Chamber

1.9 liter, 4 cylinder, direct-injection diesel engine equipped with Catalyzed Soot Filter

optical d.i. equipped with a 1.9 liter engine head and multi injection system

diesel system developed "ad hoc" by modifying a real engine with an external accessible

chamber equipped with a single-hole injector centrally located

Three diesel research systems equipped with

CR injection system:

1 2 3 Engine Type 4-stroke 4-stroke

optical

4-stroke optical Cylinder 4 in line single single

Bore [cm] 8.2 8.5 10

Stroke [cm] 9.1 9.2 9.5

Displacement [cm3] 1910 522 750 Volumetric

compression ratio 17.5 17.7 22.3 Combustion chamber

volume [cm3] 21 25 21.3

Holes number 6 6 1

Cone angle of fuel jet

axis [°] 148 148

Hole diameter [mm] 155 145 145

CAT-DPF si no no

Common Rail Injection System Nozzle Microsac Single Guide

After-Treatment System

Engine

Comparison

Diagnostica ottica

•Tecniche di tipo non intrusivo

•Tecniche di tipo non intrusivo

•Elevata risoluzione spaziale e temporale

•Elevata risoluzione spaziale e temporale

Nessuna interferenza sul fenomeno

analizzato

Nessuna interferenza sul fenomeno

analizzato

Capacità di seguire fenomeni fortemente non stazionari e di operare misure “in situ”

Capacità di seguire fenomeni fortemente non stazionari e di operare misure “in situ”

Interazione luce-materia Interazione luce-materia

Informazioni qualitative e quantitative su processi transitori

Informazioni qualitative e quantitative su processi transitori

all’interno di sistemi di combustione otticamente accessibili

all’interno di sistemi di combustione otticamente accessibili

Informazioni qualitative e quantitative su processi transitori

Informazioni qualitative e quantitative su processi transitori

all’interno di sistemi di combustione otticamente accessibili

all’interno di sistemi di combustione otticamente accessibili

 Spettroscopia di estinzione:

evoluzione temporale e spaziale della fase liquida e vapore del combustibile

 Spettroscopia di estinzione:

evoluzione temporale e spaziale della fase liquida e vapore del combustibile

Formazione della

miscela Formazione

della miscela

Tecniche di misura

SPETTROSCOPIA DI ESTINZIONE E DI EMISSIONE DELLA LUCE DALL’U.V. AL VISIBILE

SPETTROSCOPIA DI ESTINZIONE E DI EMISSIONE DELLA LUCE DALL’U.V. AL VISIBILE

 Spettroscopia di emissione per valutare la luminosità fuliggine

 Spettroscopia di emissione per valutare la

luminosità fuliggine Formazione

particolato Formazione

particolato

 Spettroscopia di emissione per valutare la chemiluminescenza di specie radicali

 Spettroscopia di emissione per valutare la

chemiluminescenza di specie radicali Auto- accensione

Auto- accensione

LUCE

SPECTRA

MAGIC BOX

SPETTROSCOPIA DI ESTINZIONE

I(), I₀() =intensità della radiazione incidente ed emergente L= cammino ottico

Nⁱ = concentrazione molare e numerica della specie i-ma estinguente K_EXT , C_EXT= coefficiente e sezione d’urto di estinzione



 



 



 

 _i ⁱ _extⁱ

ext N C

I I K L

0

1 ln

Dal coefficiente di estinzione Kext nell’ipotesi di regime di Rayleigh (D<<):

si può calcolare la frazione volumetrica f=N*V del particolato

note le proprietà ottiche delle particelle (indice di rifrazione complesso m)

    ^{λ =I}

^{exp( K L )}

I   

Legge di Lambert-Beer



  





 

 

 K m m

f_{v ext}  

SPETTROSCOPIA DI SCATTERING

Rappresentazione schematica del processo di

diffusione della luce

(scattering) _INCIDENTE^LUCE

LUCE DIFFUSA

Nel regime di Rayleigh: D<<

 ^{, ,} 

 m D f ^D 

I 

UV Mirror Window High

pressure radial pump

Engine 2

Injection pressure sensor

Combustion pressure sensor

UV Mirror Window High

pressure radial pump

Injection pressure sensor Injection pressure sensor

Combustion pressure sensor

UV Mirror Window

UV Mirror UV Mirror Window Window High

pressure radial pump

Engine

direct injection

Common Rail diesel research engine

Injection system Common Rail System Injector type Solenoid driven

Nozzle Microsac single guide

Number of holes 6

Cone angle of

fuel jet axis 148°

Hole diameter 0.145 mm Rated flow 400cm³/30s

Transparent engine

Injection Pressure

Sensor Optical

window Common Rail

Injection Pressure

Sensor Optical

window Common Rail

Engine 2

Common Rail diesel high-swirl

research engine

Injection system Common Rail System Injector type Solenoid driven

Nozzle Microsac single guide Number of holes 1

Hole diameter 0.15 mm Rated flow 67cm ³/30s

Injection system Common Rail System Injector type Solenoid driven

Nozzle Microsac single guide Number of holes 1

Hole diameter 0.15 mm Rated flow 67cm ³/30s

Engine type 4 stroke monocyl.

Bore 10.0 cm

Stroke 9.5 cm

Displacement 750 cc

Compress ion ratio 22.3:1

Connecting rod length 17 cm Divided -chamber volume 21.3 cm Optical Access Diameter 32 mm Connecting duct diam eter 0.8 cm Clearance height at TDC 0.15 cm

3 1

1 3

2

Scheme of the engine

Lateral and Top Cross-Sections

Toroidal bowl window diameter =34mm Lateral window diameter =16mm

IN

OUT IN OUT

Pressure transducer Nozzle tip

IN

OUT IN OUT

Pressure transducer Nozzle tip

IN

OUT IN OUT

Pressure transducer Nozzle tip

IN

OUT IN OUT

Pressure transducer Nozzle tip

Engine Layout

Three wide optical accesses:

- two longitudinal windows (=30 mm)

- one orthogonal window (w=10 mm and h=40 mm)

Front Lateral

Optical Set-up

Spectroscopic measurement

Extinction-scattering 2D Chemiluminescence

detector interface

Shaft

encoder Engine Lens

Injector

ICCD- Spectrograph Laser IR

Lens

Optical Breakdown

PC

ICCD: 512x512 pixels,1 kHz max recording rate, 180-900 nm spectral range.

Optical Set-up

Spectrometer

ICCD

Quarz Window

Mirror UV UV Lens

F 15cm

Quartz Window

UV - Vis Mirror ICCD

UV Objective

filter

Interference filter:

 10 nm; =310, 430, 470,515 nm Spectrometer:

150 mm, f/3.8, grating 300 groove/mm

Spectroscopic measurement

Chemiluminescence Digital imaging

Air-Fuel Mixing

Mechanical P_MAX = 300 bar

1000 rpm

2000 rpm

Common Rail P= 800bar

Effect of high pressure on fuel

injection phase

High pressure: 800bar

Digital image sequence of fuel injection phase

Liquid Distribution - Single jet

c o m b u s t i o n p r e s s u r e

d r i v e c u r r e n t

n e e d l e l i f t R O H R

- 4 0 - 3 0 - 2 0 - 1 0 0 1 0 2 0 3 0 4 0

c r a n k a n g l e [ d e g r e e ] - 1 0

0 1 0 2 0 3 0 4 0 5 0 6 0

Combustion Pressure [bar]

0 . 0 0 0 . 1 0 0 . 2 0 0 . 3 0

needle lift [mm]

1 0 2 0 3 0

Drive current [Ampere]

- 8 0 - 6 0 - 4 0 - 2 0 0 2 0 4 0 6 0 8 0 1 0 0

ROHR [a.u.]

Liquid-Vapor Distribution - Single jet

-6°-7°-5°

-3°-4°

-2°-1°TDC+1°

DIGITAL IMAGING

of fuel spray and combustion phase.

High pressure (600 bar) High pressure (600 bar)

- 3 0 - 2 5 - 2 0 - 1 5 - 1 0 - 5 0 5 1 0 1 5 2 0 2 5 3 0 c r a n k a n g l e [ d e g r e e ]

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0

Combustion Pressure [bar]

0 2 0 4 0 6 0 8 0 1 0 0

ROHR [kJ/kg/CAD]

0 1 0 2 0

Drive Current [Ampere] M ^PSOC

Main Injection

Main Injection

-7.5-7 -6.5-6 -5.5-5-3 -2.5-2 -1.5-1 -0.50.51.52

- 4 0 - 3 0 - 2 0 - 1 0 0 1 0 2 0 3 0 4 0

c r a n k a n g l e [ d e g r e e ] - 1 0

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0

Combustion Pressure [bar]

- 4 0 - 2 0 0 2 0 4 0 6 0 8 0 1 0 0

ROH

0 1 0 2 0

Drive Current [Ampere]

1 0 0 0 R P M _ s o v r . 0 . 3 S P - 9 E P 4 0 0 u s S M - 4 E M 6 8 5 u s 6 0 0 b a r

DIGITAL IMAGING

of fuel spray and combustion phase.

High pressure (600 bar) High pressure (600 bar)

Pre+Main Injection

Pre+Main Injection

injector

tip of the jet intake valve

fuel jet

Fine droplets

Liquid core

Autoignition

4°BTDC

1

0 Vapor

concentration

1.5°BTDC 2°BTDC=SOC

2°BTDC=SOC

2°BTDC=SOC 4°BTDC

7.0°BTDC

OH

0 5 0 0 0 0 1 0 0 0 0 0 1 5 0 0 0 0 2 0 0 0 0 0 2 5 0 0 0 0

emission intensity [a.u.]

1 ° A S O C 0 . 5 ° A S O C S O C

3 0 0 3 2 0 3 4 0 3 6 0 3 8 0 4 0 0 4 2 0 4 4 0 4 6 0

w a v e l e n g t h [ n m ]

OH

CH

UV-Visible spectra

Autoignition phase multi-jet

2 2 0 2 5 0 2 8 0 3 1 0 3 4 0 3 7 0 4 0 0 4 3 0 4 6 0

W a v e l e n g t h [ n m ] 0

1 0 0 0 0 0 2 0 0 0 0 0 3 0 0 0 0 0 4 0 0 0 0 0

Emission intensity [a.u.]







OH

CH

2 2 0 2 5 0 2 8 0 3 1 0 3 4 0 3 7 0 4 0 0 4 3 0 4 6 0

W a v e l e n g t h [ n m ] 0

1 0 0 0 0 2 0 0 0 0 3 0 0 0 0 4 0 0 0 0

Emission intensity [a.u.]



 OH 

3° BTDC= SOCpre CH 2.4° BTDC= 0.6°ASOCpre



 

Pre-injection - Autoignition phase

3.0° BTDC

2.5° BTDC

UV

@ 310nm

Vapor distribution Visible

Digital imaging

-3.5° -3.0° -2.5 -2.0° -1.5°

-3.5° -3.0° -2.5 -2.0° -1.5°

Visible flame @516nm

UV flame @310nm

Pre-injection - Autoignition phase

Single jet

Multi-jet Comparison

Pollutants Formation

SOOT

2 2 0 2 5 0 2 8 0 3 1 0 3 4 0 3 7 0 4 0 0 4 3 0 4 6 0

W a v e l e n g t h [ n m ] 0

1 0 0 0 0 0 2 0 0 0 0 0 3 0 0 0 0 0 4 0 0 0 0 0

Emission intensity [a.u.]







OH

2.4° BTDC= 0.6°ASOCpre



 

0 100000 200000 300000 400000 500000

Emission intensity [a.u.]

220 250 280 310 340 370 400 430 460

Wavelength [nm]







OH

0 100000 200000 300000 400000 500000

Emission intensity [a.u.]

220 250 280 310 340 370 400 430 460

Wavelength [nm]







OH

1.5° BTDC= 1.6°ASOCpre

Injection strategies

- 3 0 - 2 5 - 2 0 - 1 5 - 1 0 - 5 0 5 1 0 1 5 2 0 2 5 3 0

c r a n k a n g l e [ d e g r e e ] 0

1 0 2 0 3 0 4 0 5 0 6 0 7 0

Combustion Pressure [bar]

0 2 0 4 0 6 0 8 0 1 0 0

ROHR [kJ/kg/CAD]

0 1 0 2 0

Drive Current [Ampere] M ^PSOC

- 3 0 - 2 5 - 2 0 - 1 5 - 1 0 - 5 0 5 1 0 1 5 2 0 2 5 3 0

c r a n k a n g l e [ d e g r e e ] 0

1 0 2 0 3 0 4 0 5 0 6 0 7 0

Combustion Pressure [bar]

0 2 0 4 0 6 0 8 0 1 0 0

ROHR [kJ/kg/CAD]

0 1 0 2 0

Drive Current [Ampere]

Pre+M

PSOC Pre

PSOC M

- 3 0 - 2 5 - 2 0 - 1 5 - 1 0 - 5 0 5 1 0 1 5 2 0 2 5 3 0

c r a n k a n g l e [ d e g r e e ] 0

1 0 2 0 3 0 4 0 5 0 6 0 7 0

Combustion Pressure [bar]

0 2 0 4 0 6 0 8 0 1 0 0

ROHR [kJ/kg/CAD]

0 1 0 2 0

Drive Current [Ampere]

Pre+M+P

PSOC Pre

PSOC M PSOC P

- 3 0 - 2 5 - 2 0 - 1 5 - 1 0 - 5 0 5 1 0 1 5 2 0 2 5 3 0 c r a n k a n g l e [ d e g r e e ]

0 1 0 2 0 3 0 4 0 5 0 6 0 7 0

Combustion Pressure [bar]

0 2 0 4 0 6 0 8 0 1 0 0

ROHR [kJ/kg/CAD]

0 1 0 2 0

Drive Current [Ampere]

Pre+M+P

PSOC Pre

PSOC M PSOC P

Pre+Main +Post

fuel amount 8 mm³/stroke P _inj=600 bar

-4-3.5-2.5-3 -2-1.5-1 -0.5TDC0.511.5 2 2.533.544.555.5 66.577.525.588.599.51010.51111.51212.51313.51414.51515.51616.51717.51818.51919.52020.52121.52222.52323.52424.5252626.52727.52828.52929.53030.53131.53232.53333.53434.53535.536

Soot Evolution

- 1 0 - 5 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0

C r a n k a n g l e d e g r e e 0

2 0 4 0 6 0

ROHR [kJ/kg deg]

SOIpre

SOImain

SOIpost SOCmain

SOCpost SOCpre

- 1 0 - 5 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0

C r a n k a n g l e d e g r e e 0 x 1 0⁰

2 x 1 0⁸ 4 x 1 0⁸ 6 x 1 0⁸

Emission intensity [a.u.]

2.0°

0 600

2.5°

0 600

3.0°

0 600

3.5°

0 600

4.0°

0 600

4.5°

00 600600

5.0°

6.0°

0 600

7.0°

0 600

8.0°

0 600

9.0°

00 600600

10.0°

0 600

13.0°14.0°

0 600

15.0°

0 600

16.0°

0 600

17.0°

0 600

18.0°

0 600

19.0°

0 600

20.0°

00 600600

21.0°

11.0°

00 600600

12.0°

- 1 0 - 5 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0

C r a n k a n g l e d e g r e e 0

2 0 4 0 6 0

ROHR [kJ/kg deg]

SOIpre

SOImain

SOIpost SOCmain

SOCpost SOCpre

- 1 0 - 5 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0

C r a n k a n g l e d e g r e e 0

0 . 2 0 . 4 0 . 6 0 . 8 1

Emission intensity [a.u.]

OH

UV flame

Post-inj. – Soot oxidation phase