Modelling of Biodiesel Sprays

Ruslana Kolodnytska

Zhytomyr State Technological University, Ukraine

“We should be using nature's inexhaustible sources of energy. I hope we don't have to

wait until oil and coal run out before we tackle that.” (Edison, 1931)

Diesel and Biodiesel Spray

C. Crua et all, ICLASS 2012.

Dual frame at nozzle exit (dt = 400 ns)

Diesel fuel Biodiesel

Biodiesel The initial jet formation at 40 MPA into atmospheric pressure

T.T. Shoba et all ILASS 2011

The initial jet formation at 100 MPA into atmospheric pressure

Diesel Spray Modelling

Stip

S

•  Roizman model (2007)

,83

2

2

ggf

gD

d

vdtdSv

dtdSC

rdtSd

−⎟⎠

⎞⎜⎝

⎛ −−=ρ

ρ

)/(2,035,0 ττ gSeЭAl Sa−

=5,05,0SSb Bl τ=

• Lishevsky model

• Sazhin model (2005)

Diesel Spray Penetration Modelling, СOFM – model (Brighton University)

2 2 2( ) 1( ) ( )2f n inj D g

d mu A u t C A t udt

ρ ρ β= −

0( ) exp( )ODt ttε ετ+

= −

Kolodnytska et all, 2008

Biodiesel content and structure

Modelling of Biodiesel Property

Rapeseed oil: ZSTU, Ukraine, 2006

d max

d s

dmax

H - is the space droplet coefficient Hg  d max

2  ρσ =

Surface tension modelling

Modelling of Property by Using the Structure

[ ]( )MppP l νσ

−=4/1

[P] - parachor (temperature independent parameters)

4

1

4/1⎥⎦

⎤⎢⎣

⎡= ∑

=

n

iiim yσσ

)15(723.0)15()( −−= TCT BB ρρ

• Density modelling, (Lapuerta, 2010 )

250.718 280.899851.4711.214BDB

Nρ

+= +

+

• Surface tension modelling

Surface tension of mixture

Shadowgraphic micrographs of biodiesel (RME) sprays

15 mm (0.3 mm off-axis)

C. Crua et all, ICLASS 2012.

10 mm (0.3 mm off-axis)

Images recorded at 10 and 15 mm from the orifice at 40 MPA (atmospheric pressure)

SMD Diameter for Biodiesel Spray • SMD=0.002103 µf +0.00033 σ ( Allen, 1998, model 1) • SMD= 3.08νf 0.385(σρf)0.737ρg

0.06 ΔP-0.54 Elcotb model • dm = Ed d0 (ρg /ρfWej)– 0.266 M 0.0733 Lishevsky model • SMD= 23 d0 0.35 ΔP-0.54ρg

0.06 lν 0.1 ( new model 1)

• SMD= 0.001 lν

0.29 ( new model 2)

lν = µf 2/(σρf) - new length parameter

SMD Dimeters of Diferent Biodiesel (methyl ester of vegetable oils)

S MD  diameter,  mic ron

8.00

10.00

12.00

14.00

16.00

18.00

20.00

coconut  M

E

soya  МЕ

canola  ME

peanut    МЕ  

peanut1  M

E    

palm  ME

rapeseed  M

E    

rapeseed1  ME

Vegetable  oil  methyl  es ters  (МЕ )  

model  (1)

new  model  (2)

experiment

Kolodnytska, 2006

Fuel Eggers Parameters

Parameters of fuel Formulae Rapeseed oil Coconut oil Biodiesel Diesel Density, kg/m3 ρ f 913 915 877 826 Dynamic viscosity, Pa s µf = νfρ f 80.9 × 10-3

31.59 × 10-3 7.02 × 10-3 3.16 × 10 -3

Surface tension, N/m σ 33.2 × 10-3 34.8× 10-3 30.7 × 10-3 27.1 × 10 -3 Length Eggers parameter, µm

lν = µf 2/(σρ f) 216 31.34 1.83 0.446

Time Eggers parameter, µs

tν= µf 3/(σ2ρ f) 526 28.45 0.419 0.052

Length Time ρf – fuel density , σ – fuel surface tension, µ f – fuel dynamic viscosity

New parameters

tν= µf /(σ2ρf )

lν = µf 2/(σρf)

Droplet size distributions for biodiesel and diesel sprays

(a) 10 mm from nozzle exit at 100 MPa (b) 15 mm from nozzle exit at 100 MPa

C. Crua et all, ICLASS 2012

Vaporization history of biodiesel and diesel drops

L. Zhang, S.-C. Kong (2010). Combustion and Flame

a) biodiesel drops at different ambient temperatures and 1 bar ambient pressure

b) diesel–biodiesel blends at 912 K ambient temperature and 1 bar ambient pressure

Vapour distributions of diesel fuel and biodiesel sprays

Diesel fuel vapour

Diesel Biodiesel vapour vapour

Biodiesel fuel vapour

Biodiesel blend B20 (20% biod.)

(t=1.4 ms, Tamb=900 K, Pamb=37.58 bar) Zhang Lei, http://lib.dr.iastate.edu/etd/10268

Conclusions 1. In order to apply spray model to biodiesel it is

necessary to use model’s parameters based on fuel property. It seems promising to develop a hybrid model based on the Wave breakup model and COFM model.

2. The new formula for SMD diameter based on fuel property has been proposed. Biodiesel property has been modelled by using biodiesel structure and liquid bridge experiments.

3. The biodisel droplets has a longer heating time than the diesel droplets due to its low volatility.

Future research

•  To apply a quasi-discrete model for biodiesel droplet avaporation

CTBAPv +

−=)ln(

( ) ( )[ ]456.0354.0 195.10108.7 rrc TTRTL −+−= ω

cr T

TT = is reduced temperature

is reduced temperature at normal boiling temperature ),( cbr PTf=ω

brTis acentric factor

Antoine equation:

Pitzer equation: