The Thermal Interaction of Pulsed Sprays with Hot Surfaces – application to Port-Fuel Gasoline Injection Systems João Carvalho Miguel R. O. Panão António.

The Thermal Interaction of Pulsed Sprays with Hot Surfaces – application to Port-Fuel Gasoline Injection Systems

João CarvalhoMiguel R. O. PanãoAntónio L. N. Moreira

IN+, Center for Innovation, Technology and Policy ResearchMechanical Engineering DepartmentInstituto Superior TécnicoAv. Rovisco Pais, 1049-001 Lisbon, Portugal

Primary Droplets

Fuel InjectorIntake Manifold

Air Flow

Secondary Breakup

Spray/Wall Interaction mechanismsWall Film

Evaporation of droplets

Intake Valve

Wall Film Evaporation

Super CriticalFilm Flow

Airblast

Liquid Fuel

Elsaer, Samenfink, Hallman and Wittig (1994)

Primary Droplets

Fuel InjectorIntake Manifold

Air Flow

Secondary Breakup

Spray/Wall Interaction mechanismsWall Film

Evaporation of droplets

Intake Valve

Wall Film Evaporation

Super CriticalFilm Flow

Airblast

Liquid Fuel

Elsaer, Samenfink, Hallman and Wittig (1994)

The Thermal Interaction of Pulsed Sprays with Hot Surfaces- application to Port-Fuel Gasoline Injection Systems Background

Cryogen Spray Cooling systems

Spray Cooling in Port-Fuel Injection systems

example of Port Wain Stain treatment


Fuel Sprayfuel characteristics injection conditions

surroundingenvironment

injector position &orientation

Breakup and Vaporization

Vapor

Fuel/AirMixture

DropletLiquid Film

impingement

adherencevaporization

adherence

secondary atomization

vaporization

vaporization

secondarybreakup

air carry

air carryflow throughsolid surfaces

Panão and Moreira, Experimental Characterization of an Intermittent Gasoline Spray Impinging Under Cross-Flow Conditions, Atomization and Sprays, vol. 15, 201-222, 2005.

Tinj

Concept of Duty Cycle in a pulsed

spray

tinj

inj

inj

tDuty Cycle

T

The Thermal Interaction of Pulsed Sprays with Hot Surfaces- application to Port-Fuel Gasoline Injection Systems

Sample rate = 50kHzGainTC = 300


Panão and Moreira, Thermo- and fluid dynamics characterization of spray cooling with pulsed sprays, Experimental Thermal and Fluid Science, in Press.

finj = 30 Hz tinj = 5 ms

r = 0 mm


1. To develop of a simple method to describe the overall thermal interaction, which accounts for the complex non-linear interactions.


Nseries

Step 1 – Calculate Ensemble-Average Series

Average over 70 Series

ensemble-average series

series th

Ni series

w w1i 1series

1T r,0,t T r,0,t

N

w1

Tr,

0,t

ºC


Step 2 – Phase-Average Wall Temperature

-5% of Tw(t=0)

valid injections (Nvinj)

ensemble-average series

w1

Tr,

0,t

ºC

vinj thN

i valid injection1st

w w w w2 1 1 1i 1vinj

1T r,0,t T r,0,0 T r,0,t T r,0,0

N


Step 3 – Total Average Heat Flux

Phase-AverageWall TemperatureTransient Profile

Reichelt et al., Int. J. Heat Mass Transfer 45 (2002), pp579.

-0.02 0 0.02 0.04 0.06tim e (sec)

-4

-3

-2

-1

0

w2

Tr,

0,t

ºC

2q

r,0,

tM

W/m

iq r ,tinstantaneous heat fluxCALCULATION


Reichelt et al., Int. J. Heat Mass Transfer 45 (2002), pp579.

-0.02 0 0.02 0.04 0.06tim e (sec)

-4

-3

-2

-1

0

-20 -16 -12 -8 -4 0 4 8 12 16 20r (m m )

0

0 .1

0 .2

0 .3

0 .4

2q r kW /m

Tw = 125ºCfinj = 10Hz

injT

* *i inj i

0

q r f q r , d

time-average heat flux

2q

r,0,

tM

W/m


Step 3 – Total Average Heat Flux

R

w injimpact 0 R

1q T ,f q r drd

A

total average heat flux

-20 -16 -12 -8 -4 0 4 8 12 16 20r (m m )

0

0 .1

0 .2

0 .3

0 .4 2q r kW /m

Tw = 125ºCfinj = 10Hz

OVERALLBOILINGCURVE


f

fi nj injp b fuel fg

maximpact

m t fq C T T h

A

R

w injimpact 0 R

1q T ,f q r drd

A

w inj

sc

max

q T ,f

q

Step 4 – Spray Cooling Efficiency

spray cooling efficiency


1. To develop of a simple method to describe the overall thermal interaction, which accounts for the complex non-linear interactions.

2. To quantify the effects of injection frequency on the heat removed by the spray.


20 - 20(mm)

r = 2 mmSample rate = 50kHzGainTC = 300

Working ConditionsInjection frequency = 10, 15, 20 and 30 HzDuty Cycle = 0.05, 0.075, 0.1 and 0.15 (tinj = 5ms)Wall temperature = 125, 150, 175, 200 and 225ºC


Overall Boiling Curves

wb w bT T T


Spray Cooling Efficiency

fp w b

fg

c T TJa

h




A novel methodology is developed to quantify the thermal interaction of pulsed sprays with hot surfaces.

Total average heat flux increases with injection frequency due to an increase in net mass flux.

Nukiyama temperature is independent of injection frequency.

Spray cooling efficiency is larger for CHF and lower injection frequencies.

The Thermal Interaction of Pulsed Sprays with Hot Surfaces – application to Port-Fuel Gasoline Injection Systems João Carvalho Miguel R. O. Panão António.

Documents

hot surfaces application

hot surfaces application

overall thermal interaction

pulsed spray t inj slide

portugal slide

series ensembleaverage

solid surfaces pano

hz t inj