Automatic Continuous Vacuum Frying System

1. Automatic Continuous Vacuum Frying System Thesis Project Proposal designed by: Akhilesh Pandey Texas A & M University

2. Deep Fat Frying (DFF) • Deep fat frying is basically heat treatment processing of product in oil as a medium of heat transfer. • The deep fat fryers are of two types:- • Batch fryers • Continuous fryers

3. Batch Fryers • These fryers are basically one batch at a time small capacity fryers. • They can be both conventional deep fat fryers and vacuum type fryers. • The batch fryers are generally used in restaurants like McDonalds, KFC etc. • Batch vacuum fryers are for small scale and are tedious to work with.

4. Continuous fryers • Continuous fryers, as by name, process the product in continuous manner and may utilize conveyors and or other mechanisms to convey the product through heated oil and keep it in fryer for desired time duration. • These fryers are highly efficient and are used at industrial level. • They are fully automatic and have sensors to control the frying operation.

5. Continuous vacuum frying • This is relatively newer technique of commercializing the use of vacuum fryers, with only 2-3 companies that have actually developed a working continuous vacuum fryer. • The use of such fryer in industry is still a far cry due to cost effectiveness and local availability of such a machine. • Thus continuous vacuum frying requires more R&D to make it available for use.

6. Why Vacuum frying? • As known through various researches that vacuum frying is a better method in terms of :- • Healthy product (Low acrylamide formation). • Better quality of product (Texture, Color, Nutritional aspects etc.) • Newest trend in the line, towards which the advancing food industry is looking forward to adapt.

7. Objective • To design a cost effective prototype of fully automatic continuous vacuum fryer. • Path of research • Calculate the required dimensions of the fryer for processing different type of raw products using the same equipment. • Fabricate a prototype according to calculated dimensions.

8. Overview of the Machine • This machine utilizes three different stages for processing the raw material. • The Pre-drying Stage- carried out by Vacuum + Microwave drying of product to desired moisture content for frying (second stage). • The Multi-zone fryer- utilizes submerging of product in complete vacuum in the oil at desired temperature and frying time. • The De-oiler- consist of a centrifuge to remove any free oil from the product.

9. The idea behind • The main idea is to use conveyor belts to move the product from one stage to another. • This will require maintaining a vacuum through out the system so as to keep the units name maintained as a vacuum fryer. • This can be done by using three separate chambers with sluice gates. The gates will open/close for product’s entry/outlet. (similar to air-locks used in space shuttles)

10. Material to be used • The chambers will be designed by using stainless steel and fabricated in order to form an air tight system. • Most of the components will be designed manually to keep the cost as low as possible. • The chambers will be separated by air tight sliding sluice gates to form an air tight assembly. • The conveyor belt is a continuous wire mesh to provide maximum heat and mass transfer through it.

11. Working components • The main working components in the whole process will be: • Variable speed drive for conveyor belts.(5#s) (on/off) • Vacuum pump(3 #s) (on/off) • Gate mechanism(4#s) (open/close)

12. Main Unit in Operation Movie

13. Conveyor belt diagram

14. Technique • The whole system works in synchronization with all the conveyor belts, pumps, sluice gates. • Once the product enters the system it goes on the wire mesh conveyor belt through different stages and unit operations of drying, frying and centrifuging. • The final product is fried under vacuum for desired duration and de-oiled to bring the oil content to the optimum level.

15. Stage 1 - Microwave Vacuum Drying (MVD) • It is simply drying the product by microwave in presence of vacuum. • It relies on principle of the dielectric loss properties in microwave field. • Water molecules (highest dielectric constant) in food absorb microwave and generate evident heat effect. • This creates outward flux of rapidly escaping water vapor from food pores.

16. Stage 1 - Diagram

17. Stage 1 – Design Equations • Basic formula for calculation of drying rate: • Power dissipation: Pv = 1.41 E2 f Er tan dX 10-12 watts/in3

18. Stage 1 – Design Equations Contd… • Penetration depth: • Loss tangent = Tanδ • Dielectric loss = έ Tanδ

19. Advantages of MVD • Fast, efficient, no stray heat or left over heat. • Easy on and off control functionality. • Volumetric and selective heating. • Rated equal to freeze dried product in terms of quality retention. • In MVD boiling point of water falls down under vacuum. • Drying rate increase due to high moisture gradient.

20. Stage 2 – Vacuum Frying

21. Stage 2 – Design Equations • Basic formula for calculation of frying rate: • Effective diffusivity: Deff = A . exp(-Ea/RT) • Heat and mass balance is done to calculate the energy requirement, temperature and amount of oil etc.

22. Stage 3 – Deoiling Centrifuge • Deoiler works on the principle of mechanical separation or centrifugation of oil from fried chips. • Oil is assumed to be on surface in free form due to whole process being carried out in vacuum/ high temperature. • it is governed by very simple equation

23. Stage 3 - Diagram

24. Conclusion/Future Work • The design consideration basics followed until now will help in calculation of: • Dimensions of all the 3 stages. • RPM of required motors. • Load capacity of conveyor belts. • Design of controller and graphic interface of computer.