D. Herák

Deformation Curve Characteristics of Rapeseeds and Sunflower Seeds Under Compression Loading

Abstract The deformation curve characteristics of rapeseeds and sunflower seeds compressed using the equipment ZDM 50-2313/56/18 and varying vessel diameters (40, 60, 80, and 100 mm) were investigated. Maximum compressive force of 100 kN was applied on bulk oilseeds of rape and sunflower of measured height 20-80 mm and deformed at a speed of 60 mm∙min-1. The compression test using the vessel diameters of 40 and 60 mm showed a serration effect while the vessel diameters of 80 and 100 mm indicated an increasing function effect on the force-deformation characteristic curves. Clearly, the increasing function effect described the region with oil flow and that of serration effect described the region without any oil flow. However, it was observed that the serration effect could be due to the higher compressive stress inside the smaller vessel diameters (40 and 60 mm) compared to those with bigger vessel diameters (80 and 100 mm). Parameters such as deformation, deformation energy, and energy density were determined from the force-deformation curves dependency showing both increasing function and serration effect. The findings of the study provide useful information for the determination of specific compressive force and energy requirements for extracting maximum oil from oilseed crops such as rape and sunflower.

Mechanical Behavior of Ensete ventricosum Fiber Under Tension Loading

ABSTRACT The mechanical behavior of Ensete ventricosum fibers, expressed as the dependency of tension force in relation to the elongation, was determined for fibers with gauge length 50 mm and transformed into general linear mathematical model describing dependency of tension stress and strain. The average rupture force (10.88 ± 1.11) N, rupture stress (390.33 ± 21.96) MPa, rupture strain (0.021 ± 2 · 10–5), and volume energy (3.39 ± 0.22) J m−3 were also determined at this conducted study. Using image analyses, it was determined that the cross section of Ensete ventricosum fiber has circle shape and its dimension was specified. From the study, it implies that Ensete ventricosum fiber, with respect to its mechanical behavior under tension loading having regard to its density and to the fact that it is environmentally friendly, biodegradable and recyclable, could be used as a perspective construction material of the future. Determined model of mechanical behavior could be applied as background for further research focused on the Ensete fiber application.

Tangent Curve Function Description of Mechanical Behaviour of Bulk Oilseeds: A Review

Abstract The application of tangent curve mathematical model for description of mechanical behaviour of selected bulk oilseeds, namely jatropha, sunflower, rape, garden pea, and common bean in linear compression was reviewed. Based on the review analysis, the tangent curve function has been developed using MathCAD 14 software which employs the Levenberg-Marquardt algorithm for data fitting optimal for tangent curve approximation. Linear compression parameters including force (N), deformation (mm), energy (J), and/or volume energy (J-m-3) can equally be determined by the tangent model. Additionally, the theoretical dependency between force and deformation characteristic curves can be defined by the force coefficient of mechanical behaviour (N) and deformation coefficient of mechanical behaviour (mm-1) of the tangent model. In conclusion, the review results, however, shows that the tangent curve mathematical model which is dependent on experimental boundary conditions is potentialy useful for theoretical description of mechanical properties and deformation characteristics of bulk oilseeds in axial compression.

Application of a tangent curve mathematical model for analysis of the mechanical behaviour of sunflower bulk seeds

Abstract This paper evaluate the use of a tangent curve mathematical model for representation of the mechanical behaviour of sunflower bulk seeds. Compression machine (Tempos Model 50, Czech Republic) and pressing vessel diameter 60 mm were used for the loading experiment. Varying forces between 50 and 130 kN and speeds ranging from 10, 50, and 100 mm min-1 were applied respectively on the bulk seeds with moisture content 12.37±0.38% w.b. The relationship between force and deformation curves of bulk seeds of pressing height 80 mm was described. The oil point strain was also determined from the different deformation values namely 30, 35, 40, and 45 mm at speed 10 mm min-1. Based on the results obtained, model coefficients were determined for fitting the experimental load and deformation curves. The validity of these coefficients were dependent on the bulk seeds of pressing height, vessel diameter, maximum force 110 kN, and speed 10 mm min-1, where optimal oil yield was observed. The oil point was detected at 45 mm deformation giving the strain value of 0.56 with the corresponding force 16.65±3.51 kN and energy 1.06±0.18 MJ m-3. At the force of 130 kN, a serration effect on the curves was indicated; hence, the compression process was ceased.

Suitability of aquatic biomass from Lake Toba (North Sumatra, Indonesia) for energy generation by combustion process

Several aquatic plant species were identified as aquatic pollution of Lake Toba, North Sumatra (Indonesia); specifically, water hyacinth Eichhornia crassipes and aquatic weeds Hydrilla verticillata and Myriophyllum spicatum due to their high biomass yield which causes impenetrable mats at the bottom and surface of the lake. That complicates other vegetation growth and utilization of water areas for fishing or recreation. In attempt to clean the lake and prevent plants expansion, great amount of plants populations are removed from water but subsequent efficient utilization of such aquatic biomass is not ensured. Present research investigated energy potential of aquatic biomass originated from mentioned aquatic plants from Lake Toba and its possible utilization for energy production by direct combustion. Performed chemical analysis contained from determination of moisture, ash and volatile matter contents and calorific values. Evaluation of results proved highest suitability and energy potential of Eichhornia crassipes with gross calorific value (GCV) 16.31 MJkg–1, followed by Hydrilla verticillata with GCV 15.24 MJkg–1. Samples of Myriophyllum spicatum exhibited unsatisfactory results due to its low GCV (11.27 MJkg–1) in combination with high ash content (36.99%) which indicates complications during combustion, thus, low energy production efficiency and overall unsuitability for combustion purposes.

Effect of Length of False Banana Fibre (Ensete ventricosum) on Mechanical Behaviour under Tensile Loading

Abstract The effect of gauge length of false banana fibre (Ensete ventricosum) on the tensile strength, volume energy, and modulus of elasticity under tensile loading was examined. Fibres of gauge length L0 (mm) 10, 20, 40, 80, 160, and 320 mm were prepared and tested until rupture point at strain rate of 0.05 min−1. Mathematical models describing the mechanical behaviour of the varying gauge lengths were presented. With the increasing gauge length of fibre, the tensile strength and volume energy decreased while the values of modulus of elasticity increased. The theoretical model describing the mechanical behaviour of Ensete fibre under tensile loading presented herein provides useful information for the fibres application in industry. The determined models could be used as a background for further research focused on Ensete fibre application.

Exploitation of anaerobic fermentation of bio-degradable wastes.

Kara J., Janca E., Herak D., 2010. Exploitation of anaerobic fermentation of bio-degradable wastes. Res. Agr. Eng., 56: 8–17. The paper deals with assessment of biogas yield from mixtures of Reynoutria substrates and livestock manure. The aim was to perform laboratory experiments and suggest suitable fermenter operating conditions (dry matter content, pH, share of substrate components, thermic regime) for metanogenic digestion, then to determine its quality and assess the usability of such produced biogas.

Compressive loading experiment of non-roasted bulk oil palm kernels at varying pressing factors

Abstract Compression testing of non-roasted bulk oil palm kernels at different processing factors was performed using a universal compression testing machine and a pressing vessel witha plunger. The purpose of the research was to describe regression models of deformation, deformation energy and percentage kernel oil depending on force, speed and vessel diameter. The tested compression forces were 100, 125, 150, 175 and 200 kN, while the speeds were 5, 10, 15, 20 and 25 mm min−1. Three pressing vessels of diameter 60, 80 and 100 mm were used. Samples were compressed at an initial height of 60 mm. For varying forces and vessel diameters at a constant speed of 5 mm min−1, the values of deformation, deformation energy and percentage kernel oil ranged from 28.47±0.89 to 37.45±0.11 mm, 796±0.82 to 1795±49.01 J and 7.33±0.26 to 25.67±0.39%. At a constant force of 200 kN for different speeds and vessel diameters; the aforementioned determined parameters also ranged from 31.91±1.61 to 37.63±1.21 mm, 1012±26.76 to 1795±49.01 J and 14.66±0.42 to 24.98±1.37%. The results were statistically significant (p<0.05) or (F-ratio>F-critical), with high coefficients of determination between 0.74 and 0.99. Thus, higher force at specific speed may be needed to maximally recover kernel oil.

Evaluation of physical properties of rice used in traditional Kyrgyz Cuisine

Abstract Eight staple rice cultivars consumed in Kyrgyzstan were evaluated for physical properties in this study. The dimensions of investigated grains correspond to 5.29–6.99 mm for length, 2.52–3.10 mm for width, and 1.88–2.13 for thickness. Equivalent diameter was in range of 3.14 – 3.47 mm, surface area took 25.35–31.90 mm². The sphericity analysis values varied from 0.480 to 0.559, aspect ratio from 0.39 to 0.55, volume of the grain was measured in range from 16.25 to 22.02 mm3, bulk density values were 0.77–0.87 g/cm3, and solid density from 1.17 to 1.41 g/cm3. The porosity of grain was equal to 28.27–39.83%, thousand kernel weight correspond to 19.67 to 27.15 g, rupture force of grain was measured in range of 63.47–155.50 N, color characteristic varied in parameters L*, a* and b*, 37.58–72.19, –0.22–10.17, and 9.65–21.12, respectively. Optimum cooking time ranged from 19.33 to 33.00 min. The water uptake ratios for 30 min of soaking were 1.21–1.28, 1.18–1.45, and 1.14–1.57 for 30, 45, and 60°C, respectively. While the water uptake ratios for 60 min of soaking were 1.22–1.42, 1.19–1.54, and 1.25–1.75 for 30, 45, and 60°C, respectively. Optimal cooking time showed that imported varieties needed lower interval for full grain cooking compared to the local Kyrgyz varieties. It was found that Kyrgyz rice varieties staying more firm after cooking as compared to imported varieties and therefore more suitable for the local traditional dish such as plov.

Mechanical Behaviour of Bulk Seeds of Some Leguminous Crops under Compression Loading

Abstract The behaviours of constrained bulk columns of seeds of 3 important leguminous feed crops under compressive force applied at a uniform rate of 10 mm min-1 up to 100 kN at ≈ 9% moisture content (in dry basis) were studied to establish parameters which are relevant to the design of equipment for achieving product densification. Deformation varied significantly (P < 0.02) with crop type and was the highest in lupine seeds. Feed pea had the highest strain resistance value. Both deformation energy and volume energy requirements varied significantly (P < 0.0001) with crop type. Moduli of deformation of compressed feed pea, lupine, and soybean at an applied force of 100 kN were 269.7, 306.3, and 455.2 MPa, indicating the proportionate resistance of the crop materials to compressive strain. Precisely 4.43, 3.76, and 3.15 MJ m-3 are required to achieve 56.7, 77.0, and 67.7% or 461.7, 539.3, and 500.4 kg m-3 gains in bulk density in feed pea, lupine, and soybean, respectively. Deformation and volume energy demands correlated negatively (r = -0.934 and r = -0.78) with lipid presence. Crops with more oil appeared to deform more easily under compressive force. Higher deformations and lower energy demands may be possible at optimal combinations of force, product moisture, and depth.