Rheological and Engineering Properties of Orange Pulp. Elyse Payne Juan Fernando Muñoz José I. Reyes De Corcuera

Transcription

1 Rheological and Engineering Properties of Orange Pulp Elyse Payne Juan Fernando Muñoz José I. Reyes De Corcuera September 20, 2012

2 Acknowledgements Industry Dr. Paul Winniczuk Mr. Marcelo Bellarde Mr. Thomas Fedderly Dr. Wilbur Widmer 2

3 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)

4 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

5 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

6 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

7 Study 1 Characterize the rheological properties orange pulp ~ g/l at 4 80 ºC. (~ Industrial processing conditions) Shear stress () vs. Shear rate ().

8 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

9 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

10 Solutions to Slippage Roughened surfaces Vane geometry

11 σ (Pa) σ (Pa) Effects of Temp. and Conc C 80 C γ (s -1 ) γ (s -1 ) () 511 g L -1, ( ) 585 g L -1, ( ) 649 g L -1 and (X) 775 g L C, 500 g.l -1 4 C, 900 g.l -1

12 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) y = 0.26x R² = 0.99 ln ln K nln ln γ

13 Temperature (K) n 503 g L g L g L 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 (%)

14 ln K Effect of Temperature Arrhenius-type approach ln K ln Ea A ( RT ) /T (K)

15 Ea (kj mol -1 ) Apparent E a for K Concentration (g L -1 ) ( ) Industry 1, ( ) Industry 2, ( ) CREC. Mango Pulp: kj.mol -1 Tahini (Slippage) 30.3 kj.mol -1

16 σ (Pa) Sources of Pulp Variability ºC, ~ 500 g/l 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

17 σ (Pa) Effect of Pasteurization PME γ (s-1) () unpasteurized and ( ) pasteurized

18 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 ) ( ) ( K v D n n n n n n n Re Re 16 f For laminar flow

19 Experimental Setup Recirculation Valve PT 01 FT 01 TT 02 Flowmeter Diaphragm Pump TT 01 Pressure Transducer

20 ΔP (kpa) ΔP (kpa) 450 Effects of T and Conc. 4 ºC E+00 2.E-04 4.E-04 6.E-04 8.E ± 7 g L ± 24 g L ± 13 g L ± 11 g L Q with slippage (m 3.s -1 ) 50 ºC 864 ± 39 g L ± 44 g L ± 35 g L ± 3 g L E+00 5.E-04 1.E-03 Q with slippage (m 3.s -1 )

21 ΔP Exp (kpa) ΔP calc w/o slipage (kpa) Experimental vs. Calculated 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

22 ΔP Exp (kpa) ΔP calc w/o slipage (kpa) Experimental vs. Calculated 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

23 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 ,375 W in 4,800 h ' 165, c/kw.h Cost 100 psi $11,220

24 Pumping Costs Cost 100 psi $11,220 Assuming P 1000 psi, efficiency factor 0.5 Cost $225,000 / yr or $ /kg or $ 0.06 /gal Disclaimer: This is based on a hypothetical case and a number of non-explicit assumptions were made

25 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).

26 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

27 Study 3 Determine the thermal properties of high concentration orange pulp: Heat capacity (Cp). Thermal diffusivity ( ). Thermal conductivity (k).

28 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]

29 Thermal Diffusivity ( ) Thermal Conductivity (k) = Slope R 2 k =. ρ. Cp

30 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 ± ± ± ± ± ± ± ± ± ± ± ± No significant differences (p > 0.05) between the mean values obtained for Cp,, and k for the different pulp concentrations.

31 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)

32 Experimental Setup PT 01 TT 01 TT 02 PT 02 FT 01 Section of Heat Exchanger TT T 0 T 4 T w T 0 T 4 T w h = C pρdu 4L ln Ti Tw Tf Tw

33 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

34 Experimental setup

35 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!

36 Temperature Profiles

37 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.

38 Thank you Questions?

39 Seeking Sponsors for Food Engineering Division Lecture and Social at Annual Meeting