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Performance Evaluation of Animal Driven Oil Expeller Used in Bangladesh

D. S. Shrestha
Graduate student
Department of Farm Power and Machinery, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh

M. A. Zaman
Professor
Department of Farm Power and Machinery, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh

M. D. Hussain
Professor
Department of Farm Power and Machinery, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh

J. Tiwari
Graduate student
Department of Farm Power and Machinery, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh

Abstract/ Executive Summary:

Mechanical analysis was done for the animal driven rural oil expellers. The result obtained from force analysis was used to estimate the various forces involved in crushing process. For the mustard seed, the oil extraction pattern at different batch and moisture content were determined. Physical properties of different varieties of mustard seed were determined and correlated with optimum moisture added during crushing. The optimum percentage of water added prior to crushing was found to be the functions of initial moisture content of seed, moisture added for maximum angle of repose and maximum bulking.

Keywords: Oil expeller, Animal draught, Performance

Location: Bangladesh Agricultural University, Mymensingh, Bangladesh

Start Date:

End Date:

Program Area: Farm Mechanization

Commodity: Performance evaluation

Objectives:

To determine the Performance Evaluation of Animal Driven Oil Expeller Used in Bangladesh.

Methodology:

The mustard seeds used in the study were collected from the local market. The samples were weighed by a balance. The batch was varied from 4 kg to 5 kg at the interval of 0.5 kg. The moisture content of the mustard seed was varied from 2 to 4 % (wet basis) at the interval of 1 %. The physical parameters of the oil seeds were determined. The pulling force exerted by a bullock on the beam of the crusher was measured by a spring loaded dynamometer. Angles were measured making a suitable triangles and measuring the arm lengths. The density of oil was determined by using a density bottle. The oil content of seed was determined by Nuclear Magnetic Resonance (NMR) method. The angle of repose at different moisture content, bulk density, particle density, bulking etc. were also measured. The moisture content of seed was determined by heating the seeds for 6 hours at 130°C in an oven drier as recommended. Assuming constant angular velocity ωError! Switch argument not specified., the tension T will not lie on xz plane since there is some frictional force between pestle and mortar. To overcome these friction, T force has to incline in y-direction. The excess moisture affect the oil yield more adversely. This may be because as pestle rotates a void space will be created just behind the pestle and it should be filled with uncrushed mustard promptly for effective crushing. As the moisture content is increased the mustard seeds will be reluctant to fill the voids because of increased friction angle. This develops the unevenness of distribution of oil seed and oil cake results in the drastical decrease of oil yield. For optimum production of oil, the water m, that must be added in mustard seed before crushing, was found to be the function of three variables, ma, mb and mc. The relation is given by following empirical equation, m=k(m_a)^a (m_b)^b (m_c)^c where m = moisture added as percentage of sun-dried sample before crushing. ma = percentage of water added to the sun dried seeds (by weight) which makes the angle of repose maximum. mb = percentage of water added to the sun dried seeds (by weight) which makes the bulking maximum. mc = moisture content of sun-dried seed (w. b) k, a, b and c are constants. After transposition and multiple linear regression, the value of k, a, b and c are estimated as k = 0.0385; a = - 0.2503; b = 3.1825; c = - 0.839 Standard error was estimated to be 1.12 %. The left side of the equation (10) is always greater than right side indicating the rotation of the pestle in its own axis in clockwise direction. For efficient oil extraction the oil seed membrane must be ruptured and pressed adequately. The oil seeds break out due to compression and shearing action. If pestle is allowed to rotate in its own axis, the shearing action is greatly reduced; thus reducing the rate of oil extraction and ultimately oil production. To stop the pestle to rotate in its own axis, the right side of equation 10 must be made greater than left side. This can be done by (1) reducing the value of coefficient of friction between pestle and oilcake μ2 , (2) decreasing diameter of pestle at the point of contact with upper portion of bore hole, or otherwise arranging the parameters of equation (10) which eventually makes the right side greater than left side.

Source of Information: J. Agril. Mach. & Mech. 3 (1 & 2), 1996 : 103-110; ISSN 1024-6290.

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Oil crushing by animal driven oil crusher is a very slow process. The katari angle should not be less than 10°. For heavier load or other conditions of operation the angle may be adjusted as required. Tapering of the lower section of pestle may increase the final oil yield. 4.5 kg batch gave the optimum yield of oil. Calculated amount of water (using the empirical equation) is to be added with mustard seed prior to crushing for maximum oil extraction.

Knowledge Management: Journal