Rheological and Engineering Properties of Orange Pulp Elyse Payne Juan Fernando Muñoz José I. Reyes De Corcuera September 20, 2012
Acknowledgements Industry Dr. Paul Winniczuk Mr. Marcelo Bellarde Mr. Thomas Fedderly Dr. Wilbur Widmer 2
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)
Extractor Citrus Pulp Recovery Pulpy Juice + Defects Pulpy juice Finisher Hydrocyclone Pulp ~ 500 g/l Defects Finisher Juice Finisher Pulp ~ 900 g/l To Frozen Storage Pasteurizer Juice
Extractor Citrus Pulp Recovery Pulpy Juice + Defects Pulpy juice Finisher Hydrocyclone Pulp ~ 500 g/l Defects Finisher Juice Finisher Pulp ~ 900 g/l Aseptic Filling Juice Pasteurizer
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 ().
Shear stress (Pa) Shear stress (Pa) Basic Rheological Models Newtonian Fluid Shear rate (s -1 ) Power Law n < 1 Pseudoplastic n > 1 Dilatant Shear rate (s -1 ) Non-Newtonian Fluid Power Law K ( ) Herschel-Bulkley o K ( ) K = consistency coefficient n = flow behavior index n n
Shear stress (Pa) Wall Slippage Shear rate (s -1 ) Multiphase systems Displacement of the dispersed phase away from the solid boundaries. Low viscous liquid layer that acts as a lubricant Barnes 1995
Solutions to Slippage Roughened surfaces http://www.viscometers.org/brookfield-accessories.html Vane geometry
σ (Pa) σ (Pa) 300 250 200 150 100 50 0 Effects of Temp. and Conc. 300 250 4 C 80 C 200 150 100 50 0 0 20 40 60 80 100 0 20 40 60 80 100 γ (s -1 ) γ (s -1 ) () 511 g L -1, ( ) 585 g L -1, ( ) 649 g L -1 and (X) 775 g L -1 80 C, 500 g.l -1 4 C, 900 g.l -1
ln σ 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) 5 4.9 4.8 4.7 4.6 4.5 4.4 4.3 4.2 y = 0.26x + 4.59 R² = 0.99 ln ln K nln -2-1 0 1 2 3 4 5 ln γ
Temperature (K) n 503 g L -1 597 g L -1 643 g L -1 795 g L -1 K n K n K n K (Pa.s n ) (Pa.s n ) (Pa.s n ) (Pa.s n ) 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
ln K Effect of Temperature Arrhenius-type approach 8 7 6 5 4 ln K ln Ea A ( RT ) 3 2 0.003 0.0032 0.0034 1/T (K) 0.0036
Ea (kj mol -1 ) Apparent E a for K 16.0 12.0 8.0 4.0 0.0 500 497 511 600 606 585 637 644 649 793 817 775 Concentration (g L -1 ) ( ) Industry 1, ( ) Industry 2, ( ) CREC. Mango Pulp: 8.9-11.8 kj.mol -1 Tahini (Slippage) 30.3 kj.mol -1
σ (Pa) Sources of Pulp Variability 120 100 80 4 ºC, ~ 500 g/l 60 40 20 0 0 20 40 60 80 γ (s -1 ) ( ) CREC, and ( ) Industry 1( ) Industry 2 Batch Varieties Biological material Size/maturity Mechanical Type, operation conditions Extractor, Finisher Handling conditions Time to pasteurization
σ (Pa) Effect of Pasteurization PME 1200 1000 800 600 400 200 0 0 2 4 6 8 10 γ (s-1) () unpasteurized and ( ) pasteurized
Study 2 Determine pressure drop by capillary viscometry Slip coefficient Apparent friction factor(f) β c = Q m Q ws σ w rπ c a ff c c fc c a fe c c c g v K g v K g v K D g L fv g v v g Z Z g P 2 2 2 2 2 ) ( ) ( 2 2 2 2 2 1 2 2 1 2 K v D n n n n n n n 2 3 1 3 2 Re Re 16 f For laminar flow
Experimental Setup Recirculation Valve PT 01 FT 01 TT 02 Flowmeter Diaphragm Pump TT 01 Pressure Transducer
ΔP (kpa) ΔP (kpa) 450 Effects of T and Conc. 4 ºC 400 350 300 250 200 0.E+00 2.E-04 4.E-04 6.E-04 8.E-04 870 ± 7 g L -1 760 ± 24 g L -1 675 ± 13 g L -1 569 ± 11 g L -1 400 300 200 100 Q with slippage (m 3.s -1 ) 50 ºC 864 ± 39 g L -1 729 ± 44 g L -1 644 ± 35 g L -1 529 ± 3 g L -1 0 0.E+00 5.E-04 1.E-03 Q with slippage (m 3.s -1 )
ΔP Exp (kpa) ΔP calc w/o slipage (kpa) Experimental vs. Calculated 500 6000 450 5000 400 4000 350 3000 300 2000 250 1000 200 0 0.E+00 2.E-04 4.E-04 6.E-04 8.E-04 Q (m 3.s -1 ) 871 g.l -1 ( ) calculated ( ) experimental 761 g L -1 (Δ) calculated ( ) experimental 675 g L -1 ( ) calculated ( ) experimental 569 g L -1 ( ) calculated ( ) experimental
ΔP Exp (kpa) ΔP calc w/o slipage (kpa) Experimental vs. Calculated 500 6000 450 5000 400 4000 350 3000 300 2000 250 1000 200 0 0.E+00 2.E-04 4.E-04 6.E-04 8.E-04 Q (m 3.s -1 ) 871 g.l -1 ( ) calculated ( ) experimental 761 g L -1 (Δ) calculated ( ) experimental 675 g L -1 ( ) calculated ( ) experimental 569 g L -1 ( ) calculated ( ) experimental 1 Ø, 25 ft, ~ 6.3 GPM ~ 35 psi < P < 65 psi
P Pumping Costs W p 100 psi, 1,045 W [ ] kg 3 m J kg kg s J s W; (watts) W P 660 A processor produces 1/20 of Florida s pulp = 15,000 MT in 200 days 3 shifts W 3,125 kg h kg 52 s 115 lb min 13 GPM J kg 66052 34,375 W in 4,800 h ' 165,000 kw.h @ 6.8 c/kw.h Cost 100 psi $11,220
Pumping Costs Cost 100 psi $11,220 Assuming P 1000 psi, efficiency factor 0.5 Cost $225,000 / yr or $ 0.015 /kg or $ 0.06 /gal 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 s n ) 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
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 Cp s = Cp ref. m ref + H k. [T eq To ref m s [To s T eq + T t. t eq] T t. t eq]
Thermal Diffusivity ( ) Thermal Conductivity (k) = Slope 2.405 2 R 2 k =. ρ. Cp
Results Pulp Concentration (g L -1 ) Specific Heat Capacity (J kg -1 K -1 ) Thermal Diffusivity (m 2 s -1 ) x 10 7 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 PT 01 TT 01 TT 02 PT 02 FT 01 Section of Heat Exchanger TT 03-07 T 0 T 4 T w T 0 T 4 T w h = C pρdu 4L ln Ti Tw Tf Tw
Temperature Heat Transfer Coefficients h = C pρdu 4L Local ln Ti Tw Tf Tw T i T w Overall q U = A T LMTD T h i T i (T h o T f ) T LMTD = ln [( T h i T i)/(t h o T f )] Pulp inside the pipe Metal T Heating Media Distance from center of the inner pipe
Experimental setup
Results h 5 ft/s Overall heat transfer coefficients as function of velocity and pulp concentration, in the heating section of heat exchanger. 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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