Claims:Claim:
1. A compact centrifugal edible oil filter using passive filtration technique, the filter comprising,

Centrifugal oil filter system made up of screen filters made up of steel square mesh fabricated to filter the remnants in the used edible oil.
The filtering centrifuge consists of a rotating basket, cylindrical in shape, out of the open end of which the separated and unwanted solid wastes are removed.
Barrel at the top having hollow cylinder made up of Mild steel. Top barrel has a hopper like structure for pouring the oil inside the filtering chamber.
The filter cage with a pack of two mesh filters which is enclosed in the Top barrel.
Bottom barrel which is hollow cylindrical in shape made up of Mild steel. The bottom barrel encloses fine filter mesh sieves. The bottom barrel having a drain valve through which the filtered oil is drained.

The transmission system consisting shaft and bearing and the lower part of shaft is directly attached to the power source. The upper part is internally threaded through which a centrifugal vane is attached.

2. The compact centrifugal edible oil filter using passive filtration technique as claimed in claim 1, wherein the top and bottom barrel enclosing the filtering cage.
3. The compact centrifugal edible oil filter using passive filtration technique as claimed in claim 2, wherein the filtering cage consisting screen filters made up of steel square mesh.
4. The compact centrifugal edible oil filter using passive filtration technique as claimed in claim 3, wherein the centrifugal vane used to splash the oil towards the filtering cage.
5. The compact centrifugal edible oil filter using passive filtration technique as claimed in claim 4, wherein the vane consisting four blades is rotated centrifugally through a shaft connected to the DC power source.
6. The compact centrifugal edible oil filter using passive filtration technique as claimed in claim 1, wherein the top barrel consisting hopper arrangement for pouring the oil inside the filter.
7. The compact centrifugal edible oil filter using passive filtration technique as claimed in claim 1, wherein the bottom barrel cylindrical in shape housing the fine mesh filter screen and rotating vane blades.
8. The compact centrifugal edible oil filter using passive filtration technique as claimed in claim 1, wherein a pedestal structural arrangement to hold the complete filtering system.
9. The compact centrifugal edible oil filter using passive filtration technique as claimed in claim 5, wherein a vertical shaft connecting the vane band the DC power source.
10. The compact centrifugal edible oil filter using passive filtration technique as claimed in claim 7, wherein a cut off valve used for draining the filtered oil out of the system.
A method to filter the used edible oil, the method comprising the steps,
a. Fitting the filter cage inside the barrel;
b. Fixing the setup upright and switching on the power source;
c. Pouring the oil through the hopper inside the barrel;
d. Opening the cut off valve and collecting the filtered oil;
e. Switching off the system and removing the filter cage;
f. Decaking the filtrate manually from the cage;
g. Repeating the steps a to f.
, Description: INTRODUCTION
Edible oils used for cooking form an essential part of the modern diet(Anon n.d.). The physio-chemical and nutritional properties contribute to the flavour and taste of the prepared foods. Edible oils provide essential fatty acids which are the building blocks for the hormones which are essential to regulate body systems and acts as a carrier for the oil soluble vitamins A, D, E, and K. Contribution of Vegetable and animal is about 119 million tonnes per annum to world edible oil production.(Gunstone n.d.). The most commonly used edible oils are palm oil, coconut oil, sunflower oil, rice bran oil(Kochhar,2000). Palm oil is the widely used oil in the world. The common edible oils consist of glycerol, fatty acids, fatty alcohols, sterols, fat-soluble vitamins and other substances. The compositional qualities of edible oils are measured by different physical and chemical parameters, which include viscosity, density, smoke point and Total polar Compounds (Farhoosh 2008).
Deep frying is one of the most common practices used for the preparation of food items in commercial and domestic kitchens. The simultaneous heat and mass transfer between the oil and the food substance during deep-fat frying produces the desirable and unique quality of fried foods. Heat is transferred by convection from the oil to the product surface followed by conduction from the surface to the interior of the product (Farkas,1996). Mass transfer during frying is characterized by the simultaneous movement of water in the form of vapor from the food into the oil, and the movement of oil into the food (Hubbard,.) During deep frying the oils undergo hydrolysis, oxidation and polymerization, which eventually results in production of volatile compounds like hexanal, octanal and also non-volatile compounds such as Esters of higher fatty acids and glycerine (Andrikopoulos NK, 2002).Most of the volatile compounds evaporate with steam and the remaining compounds undergo chemical reactions which have effects on the quality of the oil.(Mishra and Manchanda 2012). The change in the physical and chemical properties will have impact on the nutritional, sensory value of the fried food items. The chemical change in the oil depends upon the factors like original quality of oil, frying conditions, and replenishment rate of fresh oil depending on the food items (Choe and Min 2007). When oils are continuously heated to high temperatures will end up in the smoke point where fat contents are broken down to glycerol and free fatty acids (FFA) resulting in liberation of smoke. The smoke point marks the beginning of both flavour and nutritional degradation giving an unpleasant and disagreeable flavour to the fried food. Reusing the edible oils after attaining the smoke point have negative impact on human health such as causing high cholesterol levels, cancer and Parkinson’s diseases (Amina Sarwar,2016).
During the process of repeated frying, the physicochemical, nutritional and sensory properties of the oil changes due to the interaction of oil with food particles (Che Man and Jasvir 2000). The deep frying will also result in contamination of the edible oil with the remnants and crumbs (May W, 1983). The contaminants and change of chemical composition are the major two reasons cooking oil degradation.
The contaminants will cause the oil to foam, bad odour, unwanted inclusions in the fried food and impart a bad taste to the fried food . (Chung J, 2004). The crumbs in the used edible oil have to be filtered in order to reuse the oil for cooking such that used cooking oil had not reached the smoke point.
CHEMICAL CHANGES IN OIL DURING DEEP FRYING
Physical changes in oils that occur during heating and frying include increased viscosity, darkening in colour, and increased foaming as frying time continues. During
deep-fat processing of foods, smoke points tend to decrease progressively and free fatty acids content of oils increase progressively. The majority of non volatile compounds are categorized as Total polar compounds. The Total Polar compounds include dimeric fatty acid, triglyceride mono hydro peroxides, cyclic fatty acids and aldehydic triglycerides. Total Polar compounds contribute to unpleasant taste and increased oxidation which leads to the oil becoming rancid and completely unusable. The content of total polar compounds is the most predominant indicator for oil quality . A per Food and Safety Standards Authority of India, the content of total polar compounds in frying oil is regulated at not more than 25%.
ART SEARCH:
TYPES OF FILTRATION
The filter used for removing contaminants is basically to trap the solids in the fluid and allow the fluid to flow down. The filtration can be implemented in two ways such as Active filtration and passive filtration. Active filtration involves physio-chemical interaction of the filter media with the fluid to be filtered, which at most times will alter the chemical properties of the fluid. In filtration of fluids, filter medias like clay, activated carbon, zeolite, silica sand are predominantly used. Active filters leach out the compounds in the fried oil. (Bheemreddy ,2001)
Passive filtration involves physical interaction of the filter media with the oils to remove the suspended inclusions through mechanical means. Passive filters like metal screens, mesh filters, rolling paper filters will remove the contaminants and have no effect on the actual chemistry of frying oil (Bheemreddy, 2001).
ACTIVE FILTRATION
(Bernard et al. 1991) Active filter media is developed with replaceable envelope made up of diatomaceous earth particles like Silicates and Alumina. When cooking oil is passed through the envelope, the crumbles are retained in the envelope. The active filter media is developed with materials activated carbon, calcium silicate, magnesium silicate. The combination of components has uniform thickness and exhibits excellent filtering properties because of small pore sizes.
(Seleman et al,,1989)A filter element constructed of stainless steel. The element includes a pair of filter media concentrically dis posed to receive parallel flow of the filtrant. The element is adapted for disassembly to remove the filter media. The various component parts of the filter element may thereafter be easily cleaned and the filter media replaced. The filter media after being removed may also be cleaned and reused if desired. The component parts include appropriate guard assemblies to protect the filter media during handling and use.
(Levy et al)The invention relates to methods and compositions for removing contaminants from edible cooking oils. Reduction s in the accumulation of contaminants Such as polar materials, free fatty acids, metals, color bodies, and Soaps is achieved by treating the oil with a composition containing effective amounts of Silica, acidic alumina, clay and citric acid. Removal of contaminants from oil according to the methods the oil and reduces costs as well as various health and Safety.
(Roy et al 1994) The device comprises a method for extending the life of an edible oil continuously with an activated carbon. The present method is suitable when edible oil is used alone in the process or mixture of two edible oils. Activated carbon can be produced by using silica, Celite and alumina filtration systems. The oil is pumped through a filter means containing a granular, pelletized or bonded activated carbon. Powdered activated carbons require a relatively large pressure gradient in continuous filtration processes. Most of the times, the oil is passed through a cartridge of granular activated carbon which is replaceable
(Whaley et al.1982) invented the filter system consists of the filter envelope applied with diatomaceous earth particles. The diatomaceous particles usually consists of Silicates and Alumina .When cooked oil is passed through the envelope, the crumbles in the oil will be retained on the envelope. After a successful filtration ,the envelope is replaced . For non disturbance of oil after filtration ,the stainless steels are used for deflection of oil. The filtered oil is allowed into drain pan for draining and oil is used for re cooking
PASSIVE FILTRATION
(Wells et al 1993) developed the filter system which has an outer housing having an inlet conduit for connecting a fryer drain outlet to supply cooking oil to be filtered to the unit, and an outlet conduit for returning filtered oil to the fryer. A pump is connected between the additional filter stage and the outlet conduit for drawing oil through the filter pump and sending oil back to the filter. The filtering system consists of three stages of filtration. First stage consists of filter screen to remove coarse particles . Second stage consists of filter canister for filtering fine particles. The Third stage is filter cartridges for filtration of very fine particles.The unit is small and compact and is completely sealed to reduce the risk of splashes and spills of hot oil. The tray can be removed easily at the end of each day for cleaning of both the filter screen, while the filter cartridges in the third stage filters can also be re moved and replaced quickly .The provision of three stages of filters allows more effective cleaning of the oil.
(Gurudoksi.1967) Two combinations of deep fat fryers with continuously operable portable cooking oil filtering circulating apparatus, each including an electric motor, an oil centrifuge and submerged centrifugal oil pump with centrifuge basket shaft and pump impeller shaft vertically aligned and coupled for simultaneous drive by the motor shaft. The first form including a fryer vat, a formed tubular support stand with a centrifuge-pump assembly; the pump submerged in the vat for direct intake of oil and The second form comprising the electric motor mounted within the frame where centrifugal pump coaxially mounted within, and with intake adjacent the bottom of, the centrifuge container jacket, a lower impeller shaft portion rotationally sealed to and extending through the jacket bottom coupled to the motor shaft, an upper impeller shaft portion Serving as the basket mounting shaft; the pump discharging through a conduit and valved spout to a fryer vat above the centrifuge and a fryer vat gravity draining from its bottom through a conduit to the basket.
(Wilson et al.1994) developed the portable oil filter. It has a tank at top and bottom for receiving cooked oil. The reversible pump is used for pumping in and out of the oil. A frame is provided with the wheels hence making the assembly portable. The two types of system are Primary system and secondary system .The secondary filter system consists of movable vertical screen attached with the bottom of oil filter .The secondary oil filter is used for filtering larger particles .The primary filter system consists of a canister attached with the bottom of the tank. The primary filter is used for filtering fine particles in cooking oil.

(Bievens et al. 1997) developed the filtering device which includes an external wire mesh filter screen and an inner, rigid perforated support shell. The shell including interior, perforated walls and has a spool which is centrally-disposed. The spool has fluid tubes by which the filter is connected to a suction pump. The shell and the interior walls is used for retaining materials of cooking oil. It passes through the support shell compartments and through the central spool. When it passes through the spool, the oil gets filtered.
MESH FILTERS
Mesh is a barrier made to filter the contaminants of liquid ,which is made of connecting the string of metal, fiber and other materials. In a wire mesh, each warp bends where it passes over a wire of the different kind. This wires are crimped for the weaving process for fine wires . The minimum size of wire which can be used depends on the material from which it is made. Thus, fine wire in aluminum ,brass, bronze or copper are not normally used for other than light duties. Stainless steel wire on the other hand is available and is used to heavy duties. Mesh wires are preferred over filter papers as mesh has large retaining capacity over filter papers
TYPES OF MESH
The mesh can be classified according to the pattern of weave and the material used in the mesh sieve
BASED ON PATTERN
• Square mesh has each wire passing alternately over or under each wire .This weave is generally referred to as plain or double crimped weave
• Twilled weave with each wire undergoing one wire at a time, alternately crossing over two and then under two wires, producing a marked diagonal pattern.
• Plain Dutch weave is zero aperture weaves. It is actually a plain rectangular weave, with the larger diameter wires as the warp and the weft wires are crimped at each pass.
• Reverse plain Dutch weave is similar to the the plain Dutch except that the thicker wire is in the weft. Reverse plain Dutch weave is substantially stronger.
• Dutch twilled weave which allows the production of the very fine grades of woven wire cloths, having the advantage of a very smooth surface on both the sides and its disadvantage is high resistance to flow of oil
BASED ON MATERIALS
• Plastic meshes are made from the polypropylene and polyethylene.
• Cloth meshes are made of woven type or knitted fabric with large number of close strings
• Metal meshes are made of different kind of metals, which give the physical and chemical properties to the mesh
• Fiberglass mesh is a closely woven with a crisscross pattern of fiberglass thread used to filtration products
KEY DIMENSIONS OF MESH FILTERS
The major terms used in square mesh filter are Aperture width w, which is the distance between the bounding wires, measured in the projected plane at the mid positions. The wire diameter d, is the diameter of the wire forming the mesh. The pitch p is the sum of the aperture width and the wire diameter. The number of apertures per unit length n, is the same number of apertures that are counted in a row one behind the other for the given unit length. Mathematically, number of apertures is represented by n (per cm) = 10 / p. The term Mesh is referred as the number of apertures per linear inches which is given by mesh = 25. 4 / p. The open screening area AO, is the percentage of the total screening surface represented by all the apertures in that surface. Open screening area AO, is defined as the ratio of the square of the aperture width to the square of the pitch which is represented by AO=(100w2)/ p2. Mesh filters are generally classified as coarse (width of 1–12 mm) and medium (width of 0.1–0.95 mm) and fine (width of 0.02– 0.16 mm)

This work focuses on the design and development of compact edible oil filter, to filter the crumbs and contaminants in the fried vegetable oils through passive filtration without changing the chemical characteristics of oil. The designs for the filter is referenced in filtration handbook. The modeling of oil filter is done in solidworks. The filtered oil is analysed in the food testing laboratory. The results clearly shows that the filtered oil can be reused again
SCOPE
During the process of repeated frying, the remnants raises out of frying activity. These contaminants will cause the oil to foam, produce bad odour, unwanted inclusions in the fried food and impart a bad taste to the fried food. These particles can adhere to the food and can change the physiochemical properties of oil, decreases the sensory value of fried food items. The contaminants in used oil can cause high cholesterol levels in human health. The contaminants in the fried oil have to be filtered in order to enable for reusage. The focus is on developing a filter to remove the crumbs in the fried oil by passive filtration and also the removal of contaminants should have no change in chemical properties and have little impact on physical properties of oil. The filter developed can filter the oil up to a capacity of 500- 750 ml. The filter is very much useful in domestic needs as the testing results drastically decreases the Total polar Compounds which is one of the criteria for reusing the oil.
DESIGN DESCRIPTION
The filter developed consists of two systems, the preliminary system contains a hopper like arrangement for receiving the oil without spilling and an interim tank for storage before filtration. The secondary filter system consists of screen filters made up of meshes. The filtrate resulting out of secondary system will be stored in the canisters. Depending on the size of contaminants and the final oil quality the filters will be employed with multiple screens of varying perforation sizes. The screens used are reusable screens. The centrifugal filtration is employed for fine filtration of crumbs in used oil.
The filtering centrifuge consist of a rotating basket, cylindrical in shape, out of the open end of which the separated and unwanted solid wastes are removed. The walls of the cylinder are usually made up of above discussed mesh filters. The fixed bed filtering as its name implies keeps the separated solids as a cake on the walls of the cylinder basket during filtration. In moving bed centrifuge the solid particles quickly separate from suspension in the feed zone and move along the basket in a direction effectively parallel to that axis of rotation. Mesh sieves range may vary from 2appertures per inch to 400. The weave of the mesh plays a major role in filtering. During passive filtration the contaminants in the oils will be trapped in the screens and after continuous filtration the contaminants will be clogged in the filter screens, this is will be mentioned as caking. The cakes formed in the filter screens can be decaked with reusable screens. The decaking process is carried out by continuously flushing the screens with water at high pressure and few decaking process involves chemical treatment.
PRIMARY SYSTEMS
The primary filtration system includes Top barrel, bottom barrel, Filter cage and mesh filters
TOP BARREL:
Top barrel has a hollow cylindrical shape made up of Mild steel (MS). The Top barrel has a length of 25.4 cm and diameter of 15 cm. A flange of diameter 24 cm is connected to top barrel for easy lifting of top barrel. Top barrel has a hopper like structure for pouring the oil. The outlet is connected to the down barrel. The filter cage with a pack of two mesh filters is enclosed in the Top barrel. The model and fabricated view of top barrel is shown in Fig 1 & Fig 2.

Fig 1: 3D model of top barrel of oil filter Fig 2: Fabricated top barrel of oil filter

BOTTOM BARREL:
Bottom barrel has a hollow cylindrical shape made up of Mild steel (MS). The bottom barrel has a length of 15.4 cm and diameter of 15 cm. The fine filter in a cylindrical shape is enclosed in the bottom barrel. The outlet of bottom barrel has an cut off valve through which filtered oil is taken. There is a vent through which the shaft passes through. The frame is attached with the bottom barrel for easy lifting of bottom barrel. The model and fabricated view of bottom barrel is shown in Fig 3 & Fig 4.

Fig 3: 3D model of down barrel of oil filter Fig 4: Fabricated down barrel of oil filter

FILTER CAGES:
The filter cage in the top barrel has a cylindrical shape. The total length of the filter cage is 18.5 cm and diameter is 12.5 cm. The filter cage has two plates in top and bottom which linked by supports. In between the plates mesh filters are sandwiched and tightened by fasteners. The filter cage can be removed by using a handle. The filter cage in bottom barrel is cylindrical in shape. The total length of the filter cage is 8.5 cm and diameter is 13.2 cm. The mesh filters are enveloped around the filter cage. The model of filter cage of top barrel is shown in Fig 5.The filter cage is coated with stainless steel 304 which is edible graded.

Fig 5: 3D model of Filter cage
MESH SIEVES
Mesh filters are made from Stainless steel. The main reason for opting stainless steel is Cleanability and weldability. The mesh filters are of square mesh because of its easy availability.
Coarse filter in the filter cage has an aperture width of 1250 µm (1.25 mm) and wire diameter of 0.4 mm. The pitch of mesh filter is 1.65 mm. The mesh of filter is approximately 16 per inches. The Number of aperture is 6.06 per cm. The open screening of filter is 57%. The coarse filter is made from Stainless steel. The diameter of mesh filter is 11.5 cm The coarse filter is sandwiched in top plate of top filter cage. The coarse filter can retain very large crumbs in cooked oil.
Medium filter in the filter cage has an aperture width of 500 µm (0.5 mm) and wire diameter of 0.20 mm. The pitch of mesh filter is 0.7 mm. The mesh of filter is approximately 36 per inches. The Number of apertures is 14.285 per cm. The open screening of filter is 51%. The diameter of mesh filter is 11.5 cm The medium filter is made from Stainless steel. The coarse filter is sandwiched in bottom plate of top filter cage The medium filter can retain large crumbs in cooked oil.
Fine filter has an aperture width of 121µm (0.121 mm) and wire diameter of 0.09 mm. The pitch of mesh filter is 0.211 mm. The mesh of filter is approximately 120 per inches. The Number of apertures is 47.39 per cm. The open screening of filter is 33%. The medium filter is made from Stainless steel. The fine filter is enveloped around the filter cage in bottom barrel. The medium filter can retain small crumbs in cooked oil. The fine filter can retain small crumbs in cooked oil. The modelling and fabricated image of fine mesh filter is shown in Fig 6 & Fig 7.

Fig 6: 3D model of fine mesh filter Fig 7 : Fabricated fine mesh filter

SECONDARY SYSTEMS
The secondary systems include Power source, Transmission systems, Vane blades and structural frame.
POWER SOURCE
The power source is given to shaft by a DC motor. It has a rated voltage of 12 V, Power of 40 W, and has a maximum speed of 1400 rpm. The shaft from the motor should be able to withstand the weight of rotating vane blades. An AC to DC convertor is used to convert the AC supply to DC to operate the motor. The modelling representation of DC motor is shown in Fig 8.

Fig 8 : 3D representation of DC motor attached with shaft

TRANSMISSION SYSTEM
The shaft and bearing forms the transmission system of the filter. The lower part of shaft is directly attached to the power source. The upper part is internally threaded through which a vane is attached. The power is transmitted to vane enveloped in the fine mesh filter. The total length of shaft is 14.5 cm and diameter is 7 cm. The bearing attached on inner down side of down barrel to reduce the friction of shaft while rotating. The bearing used is Deep groove ball bearing of 6202. The inner diameter of bearing is 15 mm and outer diameter of 19 mm. The static load capacity of bearing is 3350 N. The Dynamic load capacity is 6100 N. The maximum speed is 1400 rpm. The life value is 500 hours. The mean diameter of bearing is 25 mm. The fabricated view of transmission system is shown in Fig 9.

Fig 9: Fabricated view of transmission systems
VANE BLADES
The Vane blade is the rotating part attached with the upper most of shaft. The fine filter is enveloped around the vane blades. The vane has four blades and has a diameter of 12.5 cm. The vane blades are fabricated from Mild steel and coated with Stainless steel 304. The modelling and fabricated vane for splashing out is shown in Fig 10 & Fig 11.

Fig 10: 3D model of rotating Vane Fig 11: Fabricated rotating vane
STRUCTURAL FRAME
Frame is used to withhold the down barrel of the filter. The frame has four support. The frame is mainly provided to carry the filter easily. Frame is used to withhold the down barrel of the filter. The frame has four support. The frame is mainly provided to carry the filter easily. Frame has an AC to DC converter attached to one side where the power is converted to DC to supply power to motor.
FINAL ASSEMBLY OF FILTER:
The coarse mesh filters are tightened by fasteners with the upper plates of filter cage. The medium mesh filters are tightened by fasteners with the lower plates of filter cage. The inner view of top barrel is shown in Fig 12. The filter cage is enclosed in top barrel of filter. The fine mesh filter is fastened around the filter cage of cylindrical shape. The filter cage is kept in Bottom barrel. The motor is fitted with shaft and passes through the vent provided in the down barrel. At the top of the shaft, the vane is attached to splash out the oil. The inner view of down barrel is shown in Fig 13.

Fig 12: Fabricated Inner view of Top barrel: coarse and medium
mesh filters sandwiched in plates of filter cage

Fig 13 : Fabricated Inner view of Down barrel: Vane enclosed within mesh filter
The parts of oil filter are assembled to get the final product.The final assembly and fabricated view of oil filter is shown in Fig 14 & Fig 15.

Fig 14: Final 3-D assembly of oil filter Fig 15: Fabricated final assembly of oil filter

Fig 16: Sectioned view of oil filter
The oil filter is sectioned in Solidworks for visibility of oil filter. The sectioned view of oil filter is shown in Fig 16. The drafting view of Solid works is shown in Fig 17