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Rheological and Engineering Properties
of Orange Pulp
Elyse Payne
Juan Fernando Muñoz
José I. Reyes De Corcuera
September 20, 2012
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2
Industry
Dr. Paul Winniczuk
Mr. Thomas Fedderly
Mr. Marcelo Bellarde
Dr. Wilbur Widmer
Acknowledgements
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Background
Increased market demand for fresh-like
pulpy-juices
Orange pulp contributes to texture and other
sensory properties of fruit juices and otherbeverages
− Fresh-like, “natural” perception
Worldwide increased demand for orange
pulp, particularly in Asia An estimate of 300,000 MT of orange pulp
produced in the US (98 lb/ton)
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Finisher
Citrus Pulp Recovery
Pasteurizer
Pulp ~ 500 g/L
Finisher
Extractor
FinisherHydrocyclone
Pulpy Juice+ Defects
Defects
Pulpy juice
Juice
Juice
Pulp ~ 900 g/L
To Frozen
Storage
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Aseptic
Filling
Pasteurizer
Pulp ~ 500 g/L
Finisher
Extractor
FinisherHydrocyclone
Pulpy Juice+ Defects
Defects
Pulpy juice
Juice
Juice
Pulp
~ 900 g/L
Finisher
Citrus Pulp Recovery
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Overall Objectives
To characterize the rheology
• Studies 1 & 2
To determine the thermal properties• Study 3
To characterize heat transfer in a flowing
system• Study 4
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Study 1
Characterize the rheological properties
orange pulp ~ 500 – 800 g/L at 4 – 80 ºC.
(~ Industrial processing conditions)
• Shear stress ( ) vs. Shear rate ().
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Basic Rheological Models
•Newtonian Fluid
•Non-Newtonian Fluid
• Power Law
• Herschel-Bulkleyn
o K )(
n K
)(
Shear rate (s-1) S h e a r s t r e s s ( P a )
S h e a r s t r e
s s (
P a )
Shear rate (s-1)
Power Law
n < 1
Pseudoplastic
n > 1
Dilatant
K = consistency coefficient
n = flow behavior index
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Wall Slippage
• Multiphase systems
• Displacement of the dispersedphase away from the solidboundaries.
• Low viscous liquid layer that actsas a lubricant
Barnes 1995
Shear rate (s-1) S h e
a r s t r e s s (
P a
)
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Solutions to Slippage
Roughened surfaces
Vane geometry
http://www.viscometers.org/Brookfield-Accessories.html
http://www.viscometers.org/Brookfield-Accessories.htmlhttp://www.viscometers.org/Brookfield-Accessories.htmlhttp://www.viscometers.org/Brookfield-Accessories.htmlhttp://www.viscometers.org/Brookfield-Accessories.html
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050
100
150
200
250
300
0 20 40 60 80 100
σ (
P a )
γ (s-1)
() 511 g·L-1
, (■) 585 ·g·L-1
, (▲) 649 g·L-1
and (X) 775 g·L-1
4 °C 80 °C
050
100
150
200
250
300
0 20 40 60 80 100
σ (
P a )
γ (s-1)
80 °C 500 g .L
-1
4 °C 900 g .L
-1
Effects of Temp. and Conc.
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Power Law Parameters
Shear rate rangeof ~ 0-10 s-1
Linear portion
never exceededshear ratesabove 4 s-1
Flow behavior
index (n) Consistency
coefficient (K)
y = 0.26x + 4.59R² = 0.99
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
5
-2 -1 0 1 2 3 4 5
l n σ
ln γ
lnlnln n K
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503 g∙L-1 597 g∙L-1 643 g∙L-1 795 g∙L-1
Temperature
(K)
nK
(Pa.sn)n
K
(Pa.sn)n
K
(Pa.sn)n
K
(Pa.sn)
RSD (%) RSD (%) RSD (%) RSD (%)
277.15 0.42 70.0 0.41 123.5 0.36 137.2 0.39 233.6
24.21 77.9 14.29 51.1 13.20 51.8 28.67 40.1
292.93 0.32 50.5 0.29 91.3 0.40 109.7 0.33 180.1
3.74 60.0 5.30 49.4 22.89 43.5 14.57 51.7
310.60 0.37 50.9 0.34 83.6 0.30 88.9 0.30 146.7
34.56 61.9 35.61 50.9 23.96 47.2 9.06 47.4
330.55 0.37 43.0 0.25 61.5 0.29 78.3 0.23 115.1
34.27 47.9 16.56 48.5 17.95 45.1 4.55 47.6
353.15 0.18 33.0 0.22 59.9 0.22 74.9 0.21 112.6
60.27 55.9 57.01 0.8 40.62 4.3 47.93 11.7
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Effect of Temperature
Arrhenius-type approach
2
3
4
5
6
7
8
0.003 0.0032 0.0034 0.0036
l n K
1/T (K)
)(lnln RT
E A K a
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Apparent E a for K
• Mango Pulp: 8.9-11.8 kJ.mol-1• Tahini (Slippage) 30.3 kJ.mol-1
0.0
4.0
8.0
12.0
16.0
E a ( k J · m o l - 1 )
Concentration (g∙L-1)
500 497 511 600 606 585 637 644 649 793 817 775
(■) Industry 1, (■) Industry 2, (■) CREC.
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(▲) CREC, and (■) Industry 1(♦) Industry 2
Sources of Pulp Variability
•Batch
•Varieties
•Biological material
•Size/maturity•Mechanical
•Type operation
conditions
•Extractor Finisher•Handling conditions
•Time to pasteurization
0
20
4060
80
100
120
0 20 40 60 80
σ ( P
a )
γ (s-1
)
4 ºC, ~ 500 /L
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Effect of Pasteurization
• PME
() unpasteurized and (■) pasteurized
0
200
400
600
800
1000
1200
0 2 4 6 8 10
σ (
P a )
γ (s-1)
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Study 2
Determine pressure drop by capillary viscometry
• Slip coefficient
• Apparent friction factor( )
=−
c
a ff
c
c fc
c
a fe
ccc g
v K
g
v K
g
v K
D g
Lv f
g
vv
g
Z Z g P
222
2
2
)()( 2222212
212
K
v D
n
n nnn
n
n
2
3
13
2Re
Re
16 f For laminar flow
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Experimental Setup
Diaphragm
Pump
Recirculation
Valve
Flow-
meter
Pressure
Transducer
PT01
TT01
FT01
TT02
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Effects of T and Conc.
200
250
300
350
400450
0.E+00 2.E-04 4.E-04 6.E-04 8.E-04
Δ P ( k P a )
Q with slippage (m3.s-1)
0
100
200
300
400
0.E+00 5.E-04 1.E-03
Δ P ( k P
a )
Q with slippage (m3.s-1)
50 ºC
■ 870 ± 7 g∙L-1 ▲ 760 ± 24 g∙L-1
● 675 ± 13 g∙L-1
♦ 569 ± 11 g∙L-1
4 ºC
■ 864 ± 39 g∙L-1
▲ 729 ± 44 g∙L-1
● 644 ± 35 g∙L-1 ♦ 529 ± 3 g∙L-1
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0
1000
2000
3000
4000
5000
6000
200
250
300
350
400
450
500
0.E+00 2.E-04 4.E-04 6.E-04 8.E-04
Δ P
c a l c w / o s l i p a g e
( k P a )
Δ P E
x p
( k P a )
Q (m3.s-1)
871 g.L-1 (□) calculated (■) experimental
761 g∙L-1 ( Δ) calculated (▲) experimental
Experimental vs. Calculated
675 g∙L-1 (○) calculated (●) experimental
569 g∙L-1 (◊) calculated (♦) experimental
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0
1000
2000
3000
4000
5000
6000
200
250
300
350
400
450
500
0.E+00 2.E-04 4.E-04 6.E-04 8.E-04
Δ P
c a l c w / o s l i
p a g e
( k P a )
Δ P E
x p
( k P a )
Q (m3.s-1)
871 g.L-1 (□) calculated (■) experimental
761 g∙L-1 ( Δ) calculated (▲) experimental
Experimental vs. Calculated
675 g∙L-1 (○) calculated (●) experimental
569 g∙L-1 (◊) calculated (♦) experimental
1” Ø, 25 ft, ~ 6.3 GPM ~ 35 psi < P < 65 psi
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Pumping Costs
(watts)W;sJ
skg
kgJ ][W pW
kg
J 660 P W
3m
kg 1,045 psi,100 P
A processor produces 1/20 of Florida’s pulp = 15,000 MT in 200 days 3 shifts
GPM13min
lb 115
s
kg52
h
kg 3,125W
220,11$
c/[email protected],000'h4,800inW375,3452660
100
psiCost
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Pumping Costs
/gal0.06$or/kg0.015$oryr/000,225$
0.5factorefficiency psi,1000PAssuming
220,11$100
Cost
Cost psi
Disclaimer: This is based on a hypothetical case and a number of non-explicit
assumptions were made
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Data Variability
Diaphragm pump
• Fluctuating flow rates• Lower flow rates at higher concentrations
Pulp variability
• Two sample sources-biological material hasnatural variability
• Industrial vs. non-Industrial (handling andstorage prior to pasteurization).
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Conclusions Studies 1 & 2
Non-Newtonian pseudo-plastic fluid with slippageat > 2-4 s-1
T and Conc. have a small effect on n
50 < K < 230 (Pa ∙sn) as Conc. or T E a was moderately affected by concentration and
pulp source
c increaced with flow rate History of product handling (PME) has a huge
impact on pulp rheology
This impact needs to be fully characterized
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Study 3
Determine the thermal properties of high
concentration orange pulp:
• Heat capacity ( ).
• Thermal diffusivity (∝).
• Thermal conductivity ( ).
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Heat Capacity ()
= ∆
= . + . [
∆∆
. ]
[ +∆∆
. ]
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Thermal Diffusivity (∝)
Thermal Conductivity ( )
∝ =
2.405
= ∝ . .
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Results
Pulp
Concentration
(g L-1)
Specific Heat
Capacity
(J kg-1K-1 )
Thermal
Diffusivity
(m2 s-1) x 107
Thermal
Conductivity
(W m-1 K-1)516 ± 6 4025.0 ± 37.1 1.50 ± 0.01 0.63
617 ± 7 4051.2 ± 64.1 1.55 ± 0.02 0.66
712 ± 12 4055.7 ± 32.1 1.56 ± 0.04 0.66
801 ± 13 4068.4 ± 12.5 1.55 ± 0.07 0.65
No significant differences (p > 0.05) between the mean values obtained for
, ∝, and for the different pulp concentrations.
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Study 4
Determine heat transfer characteristics of
HCP pulp in tubular heat exchangers at
selected concentrations and flow rates• Heat transfer coefficients of orange
• Radial temperature profiles (heating and
cooling)
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Experimental Setup
Section of Heat Exchanger
ℎ =
4ln
TT03-07
PT01
TT02
PT02
T0…T 4 T
w
TT01
Tw T0…
T 4
FT01
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Heat Transfer Coefficients
∆= ( )
ln [( )/( )]
=
∆
Distance from center of the inner pipe
T e m p e r a t u
r e
Pulp
inside
the pipe
Metal Heating
Media
Ti
Tw
T∞
ℎ =
4ln
Local
Overall
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Experimental setup
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Results h
Overall heat transfer coefficients as function of velocity and pulp concentration,
in the heating section of heat exchanger.
5 ft/s
Warning! These numbers were calculating flow rates with slippage, hence they
are artificially high, hence inaccurate!
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Temperature Profiles
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Conclusions
Thermal properties (, ∝, and ) of orange pulp were
not significantly different among different concentrations.
Heat transfer coefficients were lower for highly
concentrated pulp due to its “solid-like” flow that caused
higher temperature gradients within the product.
Heat in this fluid is mainly transferred by conduction with
slight convection around the slippage region.
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Thank you
Questions?
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