Rheological and Engineering Properties

of Orange Pulp

Elyse Payne

Juan Fernando Muñoz

José I. Reyes De Corcuera

September 20, 2012

2

Industry

Dr. Paul Winniczuk

Mr. Thomas Fedderly

Mr. Marcelo Bellarde

Dr. Wilbur Widmer

Acknowledgements

Background

Increased market demand for fresh-like

pulpy-juices

Orange pulp contributes to texture and other

sensory properties of fruit juices and other

beverages

− 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)

Finisher

Citrus Pulp Recovery

Pasteurizer

Pulp ~ 500 g/L

Finisher

Extractor

Finisher Hydrocyclone

Pulpy Juice

+ Defects

Defects

Pulpy juice

Juice

Juice

Pulp ~ 900 g/L

To Frozen

Storage

Aseptic

Filling

Pasteurizer

Pulp ~ 500 g/L

Finisher

Extractor

Finisher Hydrocyclone

Pulpy Juice

+ Defects

Defects

Pulpy juice

Juice

Juice

Pulp

~ 900 g/L

Finisher

Citrus Pulp Recovery

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

Study 1

Characterize the rheological properties

orange pulp ~ 500 – 800 g/L at 4 – 80 ºC.

(~ Industrial processing conditions)

• Shear stress () vs. Shear rate ().

Basic Rheological Models

•Newtonian Fluid

•Non-Newtonian Fluid

• Power Law

• Herschel-Bulkley

n

o K )(

nK )(

Shear rate (s-1)

Shear

str

ess

(P

a)

Shear

str

ess

(P

a)

Shear rate (s-1)

Power Law

n < 1

Pseudoplastic

n > 1

Dilatant

K = consistency coefficient

n = flow behavior index

Wall Slippage

• Multiphase systems

• Displacement of the dispersed phase away from the solid boundaries.

• Low viscous liquid layer that acts as a lubricant

Barnes 1995

Shear rate (s-1)

Shear

str

ess

(P

a)

Solutions to Slippage

Roughened surfaces

Vane geometry

http://www.viscometers.org/Brookfield-Accessories.html

0

50

100

150

200

250

300

0 20 40 60 80 100

σ (

Pa

)

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

0

50

100

150

200

250

300

0 20 40 60 80 100

σ (

Pa

)

γ (s-1)

80 °C, 500 g .L-1 4 °C, 900 g .L-1

Effects of Temp. and Conc.

Power Law Parameters

Shear rate range of ~ 0-10 s-1

Linear portion never exceeded shear rates above 4 s-1

Flow behavior index (n)

Consistency coefficient (K)

y = 0.26x + 4.59 R² = 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

ln σ

ln γ

lnlnln nK

503 g∙L-1 597 g∙L-1 643 g∙L-1 795 g∙L-1

Temperature

(K)

n K (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

Effect of Temperature

Arrhenius-type approach

2

3

4

5

6

7

8

0.003 0.0032 0.0034 0.0036

ln K

1/T (K)

)(lnlnRT

EAK a

Apparent Ea 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

Ea (

kJ·m

ol-

1)

Concentration (g∙L-1)

500 497 511 600 606 585 637 644 649 793 817 775

(■) Industry 1, (■) Industry 2, (■) CREC.

(▲) 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

40

60

80

100

120

0 20 40 60 80

σ (

Pa

)

γ (s-1)

4 ºC, ~ 500 g/L

Effect of Pasteurization

• PME

() unpasteurized and (■) pasteurized

0

200

400

600

800

1000

1200

0 2 4 6 8 10

σ (

Pa)

γ (s-1)

Study 2

Determine pressure drop by capillary viscometry

• Slip coefficient

• Apparent friction factor(𝑓)

𝛽𝑐 =𝑄𝑚−𝑄𝑤𝑠

𝜎𝑤𝑟𝜋

c

aff

c

cfc

c

afe

ccc g

vK

g

vK

g

vK

Dg

Lvf

g

vv

g

ZZgP

222

2

2

)()( 22222

1

2

212

K

vD

n

n nnn

n

n

23

132Re

Re

16f For laminar flow

Experimental Setup

Diaphragm Pump

Recirculation Valve

Flow-meter

Pressure Transducer

PT 01

TT 01

FT 01

TT 02

Effects of T and Conc.

200

250

300

350

400

450

0.E+00 2.E-04 4.E-04 6.E-04 8.E-04

ΔP

(kP

a)

Q with slippage (m3.s-1)

0

100

200

300

400

0.E+00 5.E-04 1.E-03

ΔP

(kP

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

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

ΔP

calc

w/o

slip

age

(kP

a)

ΔP

Exp (

kP

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

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

ΔP

calc

w/o

slip

age

(kP

a)

ΔP

Exp (

kP

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

Pumping Costs

(watts) W;s

J

s

kg

kg

J ][ W

pW

kg

J 660 PW

3m

kg 1,045 psi, 100 P

A processor produces 1/20 of Florida’s pulp = 15,000 MT in 200 days 3 shifts

GPM 13min

lb 115

s

kg52

h

kg 3,125 W

220,11$

c/kW.h 6.8 @kW.h 165,000 '

h 4,800in W 375,3452660

100

psiCost

Pumping Costs

/gal0.06 $or /kg0.015 $or yr /000,225$

0.5factor efficiency psi, 1000 P Assuming

220,11$100

Cost

Cost psi

Disclaimer: This is based on a hypothetical case and a number of non-explicit

assumptions were made

Data Variability

Diaphragm pump

• Fluctuating flow rates

• Lower flow rates at higher concentrations

Pulp variability

• Two sample sources-biological material has

natural variability

• Industrial vs. non-Industrial (handling and

storage prior to pasteurization).

Conclusions Studies 1 & 2

Non-Newtonian pseudo-plastic fluid with slippage at > 2-4 s-1

T and Conc. have a small effect on n

50 < K < 230 (Pa ∙sn) as Conc. or T

Ea 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

Study 3

Determine the thermal properties of high

concentration orange pulp:

• Heat capacity (𝐶𝑝).

• Thermal diffusivity (∝).

• Thermal conductivity (𝑘).

Heat Capacity (𝑪𝒑)

𝑄 = 𝑚 𝐶𝑝 ∆𝑇

𝐶𝑝𝑠 = 𝐶𝑝𝑟𝑒𝑓 . 𝑚𝑟𝑒𝑓 + 𝐻𝑘 . [𝑇𝑒𝑞 − 𝑇𝑜𝑟𝑒𝑓 −

∆𝑇∆𝑡

. 𝑡𝑒𝑞]

𝑚𝑠[𝑇𝑜𝑠 − 𝑇𝑒𝑞 + ∆𝑇∆𝑡

. 𝑡𝑒𝑞]

Thermal Diffusivity (∝)

Thermal Conductivity (𝒌)

∝ = −𝑆𝑙𝑜𝑝𝑒

2.4052 𝑅2

𝑘 = ∝ . 𝜌 . 𝐶𝑝

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

𝐶𝑝, ∝, and 𝑘 for the different pulp concentrations.

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)

Experimental Setup

Section of Heat Exchanger

ℎ =𝐶𝑝𝜌𝐷𝑢

4𝐿ln𝑇𝑖 − 𝑇𝑤

𝑇𝑓 − 𝑇𝑤

TT 03-07

PT 01

TT 02

PT 02

T0…T 4

Tw

TT 01

Tw

T0…T 4

FT 01

Heat Transfer Coefficients

∆𝑇𝐿𝑀𝑇𝐷= 𝑇ℎ 𝑖 − 𝑇𝑖 − (𝑇ℎ 𝑜 − 𝑇𝑓)

ln [( 𝑇ℎ 𝑖 − 𝑇 𝑖)/(𝑇ℎ 𝑜 − 𝑇𝑓)]

𝑈 = 𝑞

𝐴 ∆𝑇𝐿𝑀𝑇𝐷

Distance from center of the inner pipe T

em

pera

ture

Pulp

inside

the pipe

Metal Heating

Media

Ti

Tw

T∞

ℎ =𝐶𝑝𝜌𝐷𝑢

4𝐿ln𝑇𝑖 − 𝑇𝑤

𝑇𝑓 − 𝑇𝑤

Local

Overall

Experimental setup

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!

Temperature Profiles

Conclusions

Thermal properties (𝐶𝑝, ∝, and 𝑘) 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.

Thank you

Questions?

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