No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Determination of some mechanical properties of castor seed (Ricinus communis L.) to design and fabricate an oil extraction machine
Abstract
This study was carried out to determine the effect of seed growing regions and loading speed on some mechanical properties of castor seed. These properties are used to design and improve related machines such as expeller that are used for extraction of oil from castor seed. Mechanical properties of castor seed were expressed in terms of rupture force and energy, bio-yield force, apparent modulus of elasticity and toughness using material testing machine. Factorial test with Completely Randomized Design (CRD) was used to study the effect of velocity (4 levels: 5, 15, 25, 35 mm min-1) and seed growing regions (Izeh, Dezfoul, Baghmalek, Shoushtar and Urmia). The results showed that the effect of seed growing region on force, modulus of elasticity, bio-yield force and rupture energy was significant. Izeh seed had the maximum rupture force (75.11 N) whereas Dezfoul and Shoushtar seed had the minimum amount of rupture force (approximately 42 N). Also, loading speed had a significant effect on modulus of elasticity and rupture energy. With the increase of loading speed modulus of elasticity of Baghmalek seed decreased significantly from 144 to 65.5 MPa. Finally, interaction effect of seed growing region and loading speed was significant for most properties. In this research work, an extrusion system was designed and fabricated for the extraction of castor oil.
... Materials with this type of behaviour are said to be viscoelastic. Studies have shown that agricultural products are viscoelastic and the determination of the engineering properties of biomaterials are difficult and complicated, since the properties are affected by moisture content, temperature and the rate of loading (Nwuba et al., 1994;ASAE, 2004;Ardebili, 2012;Niveditha, 2013). From the data available, it appeared that the viscoelastic behaviour of biomaterial is non-linear (ASAE, 2004;Ardebili, 2012;Niveditha, 2013). ...
... Studies have shown that agricultural products are viscoelastic and the determination of the engineering properties of biomaterials are difficult and complicated, since the properties are affected by moisture content, temperature and the rate of loading (Nwuba et al., 1994;ASAE, 2004;Ardebili, 2012;Niveditha, 2013). From the data available, it appeared that the viscoelastic behaviour of biomaterial is non-linear (ASAE, 2004;Ardebili, 2012;Niveditha, 2013). Since non-linear viscoelasticity theory has not been well defined in the literature, the linear viscoelastic technique was applied in the study to define the behavior of Moringa seed under the influence of external load. ...
The determination of mechanical properties of unshelled Moringa oleifera seeds was studied under compression test at varying orientations and moisture contents for postharvest equipment design. A completely randomized block design (CRBD) was applied in designing the experiment. The impact of varying moisture content levels of (10.25, 17.33, 24.47, and 32.34% dry basis) on the applied force at bio-yield and rupture, deformation, energy at rupture, crushing strength, and elastic modulus of the seed samples were investigated. Polynomial functions of the 2 nd order with coefficients of correlation ranging between 0.642 ≤ R 2 ≤ 0.999 gave the best fit and described the resulting relationships between the studied properties with respect to moisture levels at the two loading axes. Results obtained showed that the seed samples had maximum values of 80.3 N, 110 N and 257.2 J, for bio-yield force, rupture and rupture energy respectively at (10.25% d.b., in the horizontal orientation; whereas minimum values of 31.5 N, 54.9 N and 51.3 J for bio-yield force, rupture force and rupture energy occurred at (32.34% d.b.) respectively in the vertical orientation. Also, the maximum compressive strength of 5.8 N mm-2 in the horizontal orientation of the seed samples at 10.25% d.b. whereas the minimum compressive strength (2.5 N mm-2) occurred in the vertical orientation at 10.25% d.b. moisture content. The sample exhibited less resistive strength to crushing in the horizontal position as the moisture increased; whereas, in the vertical position, the cell's vertical edges provide some form of shield against external pressure which resulted in increased crushing resistance per contact area of the sample.
... Another framework done in castor seed, has considered some mechanical properties. In particular, these characteristics were measured in order to design an oil extraction machine [28,43]. However, this work was carried out to determine the effect of seed growing regions, and loading speed on some mechanical properties of the seed. ...
... It has been established that castor seed morphological features determine the requirements of the seed oil extraction machinery [12,43]. Thus, depending on the accession lot, the characterization procedure may represent a challenge that could be solve by pattern recognition, and data mining methods [34]. ...
In this study, a castor seed (Ricinus communis L.) classification process was developed using a precise image analysis technique, and several data mining algorithms. Castor seed oil has an excellent demand in the pharmaceutical sector, and it has recently aroused the interest of the biodiesel production companies. However, there are few studies describing the physical characteristics of Ricinus communis; thus, any advance in this field contributes to the design of technology that may increase the production of this oil, up to industrial levels. In fact, this work aims to contribute not only to understand the physical features of castor seed varieties, but also to unveil key information to develop better castor seed oil extraction machines. Additionally, a novel methodology to study accessions of castor seed gathered from several geographical locations is proposed. Particularly, an automatically accurate image analysis technique was implemented in order to extract color and morphological features from seeds. The data set of seeds was built considering fifty samples per accession. After that, several classification experiments were done using well known data mining algorithms in order to cluster all samples. Experimental results showed that it is possible to cluster studied seeds into ten similar classes with high accuracy (larger than 95 %). Moreover, image analysis and data mining techniques were efficient tools for the classification of seeds, and the color and morphological data gathered are really useful for the design of oil extraction equipment. In fact, the effectiveness in the correct classification instances was 100 %, with a computation time of 0.01 seconds.
... Bircan investigated loading speed effect on castor seed's mechanical properties; the rupture force, energy, apparent elastic modulus, and toughness were tested with a material testing machine. These properties are used to design and improve related machines such as expellers that are used for the extraction of oil from castor seeds [12]. Herak [13] studied the mechanical properties of leprosy seeds at different maturity stages and temperatures. ...
Products from castor seeds have been widely used in various fields. In order to study the breaking behavior and rupture mechanism of castor seed episperm during coat shelling process, the force-structure property of coating castor seed was investigated by a self-developed texture analyzer with in situ optical microscopic observation. Influences of compression distance, velocity and working temperature were studied. The results showed that castor seed episperm rupture commonly happened from the tail end to the first end. Compression distance effect can change the episperm cracking degree. Under pressing distance 2–3 mm, the episperm easily cracked into two flaps, and the breaking force stabilized at 77 N. Pressing velocity has no significant effect on episperm breaking. Temperature changes the physical property. With an increase in temperature, breaking force presents a “slope” decline; under a temperature of 120 ℃, temperature effect on the breaking force decreased significantly and the breaking force fell to about 52 N. The research results can provide theoretical basis for the castor episperm peeling.
... The knowledge of these physical and mechanical properties constitutes vital and essential engineering data in the design of 2/7 machines, storage structures, processing and for the purpose of quality control. This basic information is not only important to food engineers, but it is also useful to those who may exploit these properties and find new uses for the plant material [7]. ...
The aim of this work was to evaluate the engineering properties of two selected varieties of African yam bean (Sphenostylis stenocarpa) seeds-The brown-coated and white testa seed varieties. Physical dimensions (length, width, thickness, weight, volume, amongst other parameters) of the selected test seeds were measured using appropriate devices. Established mathematical formulae were used in the computation of the data generated to deduce several relevant engineering properties of the seeds. The values derived for all parameters are presented in this work. From the results obtained, the mean values for length, width and thickness (all in mm) were generally lower for the white variety than for the brown variety. The average arithmetic and geometric mean diameter values further confirmed this, as was evident from the bigger sizes of the brown seeds compared to the white species. The mean sphericity values for both seeds implied that both seeds were closer to a sphere in shape, though the white seed type had a higher tendency to roll when placed at a particular orientation to improve emptying (as in hopper or conveyor belt/inclined plane platforms). The specific surface and mean surface areas suggested that both seed varieties would fall through a stream of air at the right velocity while lighter/irregularly-shaped chaff/extraneous matter are blown away during pneumatic separation (such as aspiration/winnowing processes) or remain on the belt during pneumatic conveyance. The mean values for volume, bulk density solid density, 1,000-seed mass, unit mass and porosity values indicated that the seeds will not float in water and these values would help to separate unwanted particles from the seeds during wet cleaning on the basis of buoyancy differences. Though, more seeds of the white variety would occupy the same space than the seeds with brown seed coat. The values of angle of repose suggested that the seeds would readily form heaps during collection/packaging and flow out readily during emptying of the holding vessel. The coefficient of static friction on various surfaces (plywood, glass, stainless steel, aluminium, planed wood surface and formica) was indicative of the trend of increased resistance to sliding of the bulk seeds when placed on the respective surfaces. This would be useful in the design of conveying devices like raw materials' reception plane, processing machine hoppers or agricultural machine (planter) hoppers. All the values generated may be exploited in the design and fabrication of equipment to manage, convey, process, contain or preserve African Yam bean seeds.
... Работа разрушения зерен определяется из соотношения [6]: ...
The compression processes of grains of winter wheat cultivar Smuglianka and spring wheat cultivar Ranniaya for the case of loading along the smallest axis of the ellipsoid, which approximates the shape of the grain, have been explored. Typical dependence of grain deformation on the forces applied to it has been examined. A well-known technique for determining the Young’s modulus of the grain in the field of its elastic deformation has been applied. The dependence of the fracture work of the grains of wheat cultivar Smuglianka and Ranniaya on their moisture content has been determined and the regression dependences of the rigidity and the Young’s modulus of grains of wheat cultivar Smuglianka on their moisture content have been obtained.
... The share of other oilseeds and tobacco from total industrial harvest is 3.01% (Agricultural Ministry of Iran, 2015). Iran has also potentials for farming energy plants like castor (Ricinus communis) (Safieddin Ardebili et al., 2012), jatropha (Jatropha curcas) ( Babazadeh et al., 2015), camelina (Camelina sativa) (Mohammadi-Nejad et al., 2018), and algae . ...
... Rudolf Diesel used peanut oil as fuel in 1900 [28]. Researchers have investigated many vegetable oils and their derivatives, which are most commonly biodiesel or the monoalkyl esters of oils or fats, for their potential application as fuel, whether for transportation or heating purposes [29][30][31][32][33][34]. ...
... Effect of 6 different regions & loading speed of castor seeds on rupture force & energy, bio yield force, apparent modulus of elasticity and toughness was studied by M. Safieddin Ardebili et al [28]. Data was further analysed with SPSS software using ANNOVA and completely randomised design (CRD). ...
The quality of agricultural products is mainly dependent on the grading methods adopted. In India, agriculturalists widely use the manual methods of grading which are prone to error and labor intensive. This paper reviews the present methods of grading of agricultural products and the potential application of physical and mechanical properties for quality grading.
... A lot of researches on mechanical properties have been reported for different seed types such as pea seed (Paksoy and Aydin, 2006), melon seed (Abu et al., 2007), soybean (Kibar and Öztürk, 2008), barbery fruit (Fathohzadeh and Rajabipour, 2008), flax seed (Ayman, 2009), jatropha seed and kernel (Karaj and Muller, 2010), palm-kernel seed (Ozumba and Obiakor, 2011), white sesame seed (Hosain, 2012), castor seed (Ardebili et al., 2012) and canavalia seed and kernel (Niveditha et al., 2013). Moreover, due to present prevalent drudgery associated with low output in soursop seeds manual dehulling and oil extraction processes, has necessitated the need to study some moisture-dependent mechanical properties of soursop seeds and kernels since it does not appear to be available in literature. ...
Soursop seed is an economically important oil seeds which contains about 40% oil useful in the chemical industries. The present prevalent drudgery associated with low output in its manual dehulling and oil extraction processes, has necessitated the need to study its mechanical properties to enhance the effective mechanization of its handling and processing unit operations. This study therefore, aimed at evaluating some mechanical properties of soursop seeds and kernels. The properties (rupture force and energy, bio-yield force and energy, deformation and hardness at seed vertical and horizontal direction and kernel resting position) were determined using Instron Testing Machine. Within moisture content of 8.0 to 32.5% (db), rupture force, rupture energy, bio-yield force, bio-yield energy, deformation and hardness ranged from 43.98-20.0 N, 40.0-188.0 N.mm, 41.5-22.3 N, 6.73-1.89 N.mm, 1.89-3.58 mm and 23.27-5.59 N/mm, respectively, at the seed horizontal direction, from 576.8-787.7 N, 512.0-1488.6 N.mm, 144.9-1751.7 N, 41.0-246.0 N.mm, 2.19-4.42 mm and 29.1-35.8 N/mm, respectively, at the seed vertical direction and from 576.8 to 787.7 N, 512.3 to 1488.6 N.mm, 44.9 to 1751.7 N, 6.73 to 1.8 N.mm, 2.19 to 4.42 mm and 29.31 to 31.66 N/mm at the kernel resting position. The study established that the mechanical properties of soursop seeds and kernels depend on moisture content (p≤0.05), which is useful for engineers in the development of soursop seed dehuller and oil-expeller.
... Absorbed (rupture) energy by the grains samples at rupture point was determined by calculating the area under the force-deformation curves from the follow equation given by Ardebili et al. (2012) ...
... dissertations and Ph.D. thesis. The results and the findings of the R & D on various topics have been either presented in conferences and/or published in journals [67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82]. The biodiesel R & D activities also resulted in a few number of research patents [83][84][85][86][87][88][89][90][91][92][93][94][95][96]. ...
This paper describes a brief review of biodiesel R & D developmental trends at Tarbiat Modares University (TMU) bio-energy research laboratories (lab.), Tehran, Iran. The developmental trends at includes potential and feasibility study, cultivation of a sample bioenrgy farm, technology innovation and its scale up (patents) for fuel processing, and finally the fuel application in diesel engines. A national investigation was carried out to find out the possible potential of sus-tainable feedstock for biodiesel production. The results showed that easily available biodiesel feedstock is waste cook-ing oil with a maximum potential of 750 mil.lit and an approximately 350 mil.lit. of collectable waste cooking oil. A castor oil plant farm was cultivated to harvest castor plant seeds, extract its oil, produce biodiesel fuel and use it in die-sel engines. This led to a series of patent and consequently technology innovation from 7 lit. lab. scale to semi-con-tinuous, semi-industrial scale of 2 ton capacity.
Knowledge of physical and mechanical properties of cereal grains is important for designing handling and processing equipment. However, there is still a lack of knowledge on the influence of moisture content on the physical-mechanical properties as related to machine design. The aim of this study was to investigate and describe the changes in select physical-mechanical properties of maize, rice, and soybeans at various moisture content (10%, 14%, 18%, 22%, 26%; wet basis) and their compression behavior at two loading rates of 1.25 mm/min and 125 mm/min. The measured physical and mechanical properties include size, shape, and breakage force of single kernels. It was found that an increase in moisture content increased the kernel size, altered the kernel shape, and decreased the bulk density. The effects of moisture content and loading rate on breakage force, stress, and energy varied depending on the grain type. Our results indicated that an increase in moisture content changed the mechanical behavior of grain kernels from brittle to viscoelastic. To prevent kernel damage during processing and handling, the measured force and stress during compression can be used as the limit value for designing equipment.
With the increasing amount of agricultural waste in the world, as well as their disadvantages and environmental problems, it has attracted more attention in the international community. Therefore, suitable methods for agricultural waste management should be used. In addition, biomass, as one of the largest sustainable energy sources in the world, has countless alternative energy sources. It exists in various forms all over the world and due to its availability, numerous economic and environmental benefits, it can be used to replace fossil fuels. One of the suitable methods for this purpose is the use of pyrolysis technology, through which this type of agricultural waste can be converted into materials with high added value and biofuel. In this article, the importance of pyrolysis of agricultural waste as a method for waste management will be discussed by examining various scientific sources and according to the available statistics and information. Also, the effective factors in the pyrolysis process, which include: type of biomass, particle size, reaction atmosphere, temperature, heating rate, steam retention time and type of reactor, are analyzed and the results of each factor are analyzed.
Biogas is a practical way of recycling bio-wastes that can be utilized as a fuel for co-generation of electricity and heat. Livestock and agriculture-based resources have considerable potential for bio-power generation mainly due to their comparatively low cost. However, the contribution of agricultural residues has been neglected within this context in Iran. This study aims to assess Iran’s potentials in bio-power generation from both animal and agriculture-based resources to provide an accurate/realistic estimate of the resource availability. The studied energy crops were wheat, rice, barley, maize, potato, apple, grape, alfalfa and other industrial crops including sugar cane and sugar beet. The total amount of agricultural waste is assessed to be 24.3 million tones that can be considered potential feedstock to produce 6,542 million m³ of biogas, 2,443 million liters of bio-butanol, and 2,082 million m³ of bio-hydrogen. In addition, the biogas potential from livestock and slaughter wastes is estimated to be 11,523.84 and 16,026 million m³/year, respectively. The findings indicated that there is considerable potential for bio-power generation in Iran. The analysis estimated that Iran’s total potential for bio-power generation from these organic matters was around 62,808×10⁶ kWhyear⁻¹, accounting for 27% of the total electricity consumption in the country. The greenhouse gas emission mitigation from bio-based electricity generation would be about 4,096 thousand tons of CO2-eq/year, which account for up to 0.6% of Iran's annual greenhouse gas emissions. To the best of the author’s knowledge, this is the first report assessing the emission inventory and emission allocation of CO2 from both livestock manure and the open burning of crop residues in Iran. This paper provides valuable insights and information for policy-makers to formulate long-term energy policy by taking advantage of these bio-wastes in Iran as a case study.
Physical and mechanical properties of food crops gain importance during design, improvement and optimization of separation and cleaning. In this study, some physical and mechanical properties of corn seeds were determined as a function of moisture content in the range of 5.15 to 22% d.b. The average length, width, thickness and arithmetic diameter were increased by 6, 2.2, 1.66, and 3.3%, with increasing moisture content, respectively. In the moisture range from 5.15 to 22% d.b., the results showed that, the thousand seed mass increased from 267.7 to 305.8 g, the porosity from 31.41 to 45.98%, the static angle of repose from 42 to 57, and the coefficient of friction on compressed plastic, plywood and galvanized iron sheet surfaces were increased from 0.36 to 0.67, 0.36 to 0.6 and 0.38 to 0.57, respectively. The bulk density decreased from 679.1 to 632 kgm-3 and true density increased from 999.33 to 1170.49 kgm-3. Moreover, surface area and volume increased as the moisture content increased. The rupture energy of the grains increased in magnitude with an increase in moisture content, while rupture force was decreasing.
Sorption isotherms of castor seeds were evaluated at 30, 40, 50 and 60ºC using the static gravimetric method. Sigmoid trends were observed for isotherms obtained showing a clear effect of temperature. Experimental values were adjusted using the modified isotherms of Henderson, Halsey, Oswin and Guggenheim-Anderson-de Boer (GAB). Models were compared using four statistics parameters. The results showed that Modified Henderson model adjusted adequately the experimental values in the range of temperature evaluated. The experimental values of the safe storage moisture content for castor seeds varied between 6.1 to 8.4 % (d.b.) between 20 and 40ºC, showing lower values than those reported for other traditional oilseeds as sunflower or rapeseed. The sorption heats evaluated from the combination of Clapeyron equation and Modified Henderson equation varied between 3400 and 2373 kJ/kg for moisture contents between 1 and 28 % (d.b.). Through Othmer relationship the value of the ratio Lb/Lf varied between 1.01 and 1.34 (for 14.5 and 1% d.b. moisture content respectively). The values obtained showed an exponential relationship with moisture content, of the form Lb/Lf=1+0.44exp(-0.17M) with a determination coefficient R2 of 0.97.
Physical properties of kernels, grains, and seeds are necessary for the design of equipment to handle, transport, process and store the crop. The physical properties of flaxseeds have been evaluated as a function of seed moisture content, varying from 6.09% to 16.81% (d.b.). In the moisture range, seed length, width, thickness, arithmetic mean diameter, and geometric mean diameter increased linearly from 4.27 to 4.64 mm, 2.22 to 2.38 mm, 0.85 to 0.88 mm, 2.45 to 2.63 mm and 2.00 to 2.12 mm respectively with increase in moisture content. One thousand seed weight increased linearly from 4.79 to 5.32 gr. The true density increased with moisture content from 1000 to 1111 kg/m3 while bulk density decreased 726.6 to 555.6 kg/m3 in the range of moisture content between 6.09% and 16.81%, d.b. Also, porosity values of flaxseeds increased from 27.34 to 57.44%. The highest static coefficient of friction was found on the plywood surface. The static coefficient of friction increased from 0.537 to 1.073, 0.515 to 0.933, 0.472 to 0.975, 0.499 to 0.877, 0.544 to 0.862, and 0.472 to 0.824 for plywood, aluminium, stainless steel, galvanized iron, polypropylene knitted bag and kraft paper surfaces, respectively. The angle of repose increased linearly from 21.6° to 33.4° with the increase of moisture content.
Designing the equipment for processing, sorting and sizing agricultural crops requires information about the crops' physical properties. The physical properties of castor seed were evaluated as a function of moisture content in the range of 6.24 to 12.56% d.b. (dry basis). The average length, width, thickness and one thousand seed mass were 10.24mm, 6.81mm, 5.05mm and 195g, respectively at a moisture content of 6.24% d.b. The geometric mean diameter and sphericity increased from 7.06 to 7.16mm and 67.62 to 67.84% as moisture content increased from 6.24 to 12.56% d.b., respectively. In the same moisture range, bulk density decreased from 517.64 to 497.65 kg m(-3), true density increased from 908.99 to 989.65 kg m(-3), and the corresponding porosity increased from 43.05 to 49.71%. As the moisture content increased from 6.24 to 12.56% d.b., the repose angle, terminal velocity and surface area increased from 31.5 to 34.3 degrees, 5.56 to 5.79 ms(-1) and 131.97 to 136.08mm(2), respectively. The static coefficient of friction increased on three structural surfaces namely, glass (0.249-0.271), stainless steel (0.314-0.334) and plywood (0.324-0.344) in the moisture range from 6.24 to 12.56% d.b. Linear regression equations were used to express the physical properties of castor seeds as a function of moisture content. High correlation coefficients were found with a significance level of 95%.
A rational approach to the design of peanut processing machinery requires, among others, a knowledge of its physical properties. Foremost among those that affect the design are the properties associated with its geometry. Within such a context this paper deals with the determination of the dimensional properties of peanut as one aspect. This part involves geometric shape, size parameters, size distributions, probability versus dimension, correlation between dimensions, dimensional classification, shell thickness and void. The resulting data of interest for peanuts grown in Turkey is presented and discussed.
Aci Findik, Cakildak, Tombul, and Güney Karasi varieties of hazelnut were loaded between two parallel plates to determine the specific deformation, rupture force, and rupture energy required to initiate shell and kernel rupture. The tests were carried out at two deformation rates of 0·52, and 0·91mms−1, four moisture contents of 6, 11, 15, and 18% w.b., and three axes (X,Y,Z). The X-axis is the longitudinal axis through the hilum, while the Y-axis is the transverse axis containing the major dimension at right angles to the longitudinal axis, and the Z-axis is the transverse axis containing the minimum dimension. Physical characteristics of nut and kernel such as mass, dimensions, geometric mean diameter and sphericity were determined. Specific deformation and rupture energy of the shell generally increased in magnitude with an increase in moisture content while rupture force decreased for compression along the X- and Y-axis. The highest nut shell specific deformation, rupture force and rupture energy among the four varieties were obtained for Aci Findik nuts loaded along the Z-axis at a deformation rate of 0·52mms−1. The Tombul and Güney Karasi varieties had the highest kernel rupture force and rupture energy, respectively.
The modulus of elasticity, maximum compressive contact stress and the force relaxation behaviour of single wheat and canola (rapeseed) kernels at different moisture contents were determined. In the force relaxation experiments, the effect of different deformation rates and strain levels were examined. Results indicated that the modulus of elasticity and maximum compressive contact stress decreased linearly with increase in moisture content of the grains. A three-term Maxwell model was found to adequately describe the force relaxation behaviour of both grain kernels when compared with one- and two-term models. The optimum number of terms in the model was determined based on the criteria of maximum relative difference (⩽5%). The moisture content was found to have a significant effect on stress relaxation behaviour of both grains.
The operation of cracking Macadamia nuts is the most critical and delicate step for achieving high-quality kernels. The nuts, usually at high moisture content, are dried to a recommended moisture, before cracking, in a process that takes from 3 to 4 weeks at the expense of large energy consumption. The present paper examines the basis of shell rupture which is needed for the development of new methodologies or techniques to reduce the drying period and to obtain a more efficient kernel extraction process. Requirements in terms of force, specific deformation and energy for initial rupturing of the macadamia nut shell under compression were experimentally investigated as a function of moisture content, nut size, and compression load position. The experiments have shown that there is a compression position for which force, specific deformation and energy values are minimal, independent of nut size and shell moisture. A damage evaluation of compressed nuts showed a trend for the void between kernel and shell to be the greatest at this position with the force acting longitudinally through the hilum.
Results are reported of the first part of a research project designed to develop machines for shelling melon seeds and for mechanical extraction of oil from the shelled seeds. The design of a machine for shelling the seeds is influenced by the size (length, breadth and thickness) of the seeds. For the design of cleaning and washing machines, the surface area of the flat side of the seeds is taken into consideration.The performance of the shelling machine is influenced by the behaviour of the seeds when subjected to bending. In the present study the results of the behaviour of the seeds when bent at different moisture contents are reported.Based on a large number of measurements, empirical equations are proposed to express the correlation between the 3 principal dimensions for the 2 most common types of melon seed produced in the Western State of Nigeria. Another set of equations are suggested to estimate the surface area of the flat side with reasonable degree of accuracy from the measurement of either the length or the breadth of the seed.
Some of the physical properties of castor nut were studied, namely: shape, size, surface area, angle of repose, static coefficient of friction and the behaviour of the nut under compressive loading. Representative samples of plant material were collected from three varieties. The results of the investigation show that the frequency distribution of the size, shape and contact area for nuts of each variety follow a normal distribution curve. The angle of repose of the nut ranges between 25 and 29°. Castor nut Evahura had the highest value of angle of repose. The hardness values for the nuts were 23·6, 25·6 and 70·9 kN/m2for castor nut Ojji, Evahura and Asbowu varieties, respectively. The coefficient of sliding friction for each variety of nuts showed varying values on different structural surfaces.