Heat Transfer in Canned Liquid/Particle Mixtures Subjected To Axial Agitation Thermal Processing

1. Heat Transfer in Canned Liquid/Particle Mixtures Subjected To Axial Agitation Thermal Processing Department of Food Science and Agricultural Chemistry McGill University July 15 , 2008 CSBE Conference Mritunjay Dwivedi&H.S. Ramaswamy

2. Introduction Thermal Processing • Most efficient method of food preservation • Principles of thermal processing: • Safety and shelf stability • Reduce the number of microorganisms of public health concern • Create an environment to suppress the growth of spoilage microorganisms

3. Introduction • Today the Consumer demands more than safe and self stable product • High Quality • Convenience in end use • Processors demand technology which is • More efficient • Cost effective • High speed in nature • HTST process is designed to meet the aforementioned processors and consumers demand • Minimizing the severity of heat treatment • Promoting product quality

4. Three Major developments in HTST processing Aseptic processing and Packaging (1)

5. Three Major developments in HTST processing Thin Profile Packaging and Processing (2)

6. Three Major developments in HTST processing Rotational retorts Processing (3)

7. Two Different Modes of Rotation in Agitation retorts Rotational Modes mg mg mg mg mg End over end rotation (Batch Operation) Axial Rotation (Continuous Operation)

8. Several Studies Conducted in End Over End Agitation Processing But very little information is available on axial agitation processing

9. Process Parameters U and hfp are commonly used to quantify the heat transfer process. Particle hfp Retort Liquid U U : Overall heat transfer coefficient hfp: Fluid to particle heat transfer coefficient

10. Heat transfer in free axial agitation is it difficult • Attaching temperature sensors • Collection of data • Knowledge of U and hfp is important in predicting the particle center lethality

11. Overall Objective The overall objective of this presentation is to carry out a detailed evaluation of heat transfer to canned particulate fluids under rotary processing

12. Heat transfer studies of particle-liquid mixtures canned foods in free axial mode Modification of Stock rotomat similar to FMC steritort

13. Modification of Stock Retort RETORT SHELL CAGE Attachments CAN Detail – Attaching Cans in Axial Mode of Rotation

14. Methodology EOE vs Free vs Fixed Axial shell Cage 32 Circuit HUB Tl Tl SUS Attachment Tl S-28 NR rotating thermocouple Placement of cans in EOE and Axial Mode

15. Heat transfer studies of particle-liquid mixtures canned foods in free axial mode S-28 Ecklund Thermocouple To data logger Modification of Stock rotomat similar to FMC steritort Compare heat transfer rates between Axial and EOE mode

16. Results and Discussions Development of a suitable methodology to measure convective heat transfer coefficients in free axial mode

17. Methodology to U & hfp U & hfp (Free axial Mode) Models (U & hfp Vs for free axial mode) + Liquid temperature Data from wireless sensors (Free Axial) Overall energy balance equation

18. Results and Discussions Evaluation of the effects of system parameters on heat transfer coefficients with Newtonian fluids during axial rotation

19. Free Vs. Fixed Axial Mode Effect on hfp

20. Free Axial Mode Effect of Particle size and Conc. on U & hfp

21. Free Axial Mode Effect of Particle density and Conc. on U & hfp

22. Results and Discussions Dimensionless correlations for convective heat transfer to canned liquid particulate mixture subjected to axial and end-over-end rotations under natural and forced convection

23. Dimensionless correlations set up Neural network models set up

24. Dimensionless Groups

25. Regression Analysis used A multiple linear regression analysis for developing forced convection correlations A step-wise multiple non-linear regression analysis was used to develop the mixed convection dimensionless correlations

26. Nu = A1 ( GrPr) A2 + A3 (ρp/pl )A5, (dp/Dc)A6, ReA7, FrA8, PrA9, PCA10 Free Convection Forced Convection

27. Comparisons of errors for ANN models vs. Dimensionless correlations • for liquid with particulates Comparisons of errors for ANN models vs. Dimensionless correlations for liquid without particulates

28. Conclusions Modification of the existing cage of the pilot stock rotomat was successful U was significantly higher in case of axial mode than in EOE mode of agitation, contrary to study made by Naveh and Kopleman (1980) A methodology was developed for the measurement of U and hfp subjected to free axial agitation. With an increase in rotational speed, particle density and retort temperature, there was an increase in the associated hfp and U values

29. Conclusions T-Test showed no significant difference between the performance of standard thermocouples and wireless sensors. Dimensionless correlations for mixed and pure forced convection were developed with and without particulates in Newtonian fluids during all modes of agitation Higher coefficients of correlations showed that in all forced convection situations, the natural convection phenomenon continues to operate because of buoyant forces. ANN models yielded better results those from the dimensionless correlations.

30. Thank You