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Abraham Kabutey, David Herak, Cestmir Mizera and Petr Hrabe

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.

Open access

Abraham Kabutey, David Herak, Rostislav Choteborsky, Čestmír Mizera, Riswanti Sigalingging and Olaosebikan Layi Akangbe

Abstract

The study described the oil point and mechanical properties of roasted and unroasted bulk oil palm kernels under compression loading. The literature information available is very limited. A universal compression testing machine and vessel diameter of 60 mm with a plunger were used by applying maximum force of 100 kN and speed ranging from 5 to 25 mm min−1. The initial pressing height of the bulk kernels was measured at 40 mm. The oil point was determined by a litmus test for each deformation level of 5, 10, 15, 20, and 25 mm at a minimum speed of 5 mmmin−1. The measured parameters were the deformation, deformation energy, oil yield, oil point strain and oil point pressure. Clearly, the roasted bulk kernels required less deformation energy compared to the unroasted kernels for recovering the kernel oil. However, both kernels were not permanently deformed. The average oil point strain was determined at 0.57. The study is an essential contribution to pursuing innovative methods for processing palm kernel oil in rural areas of developing countries.

Open access

Riswanti Sigalingging, David Herák, Abraham Kabutey, Oldřich Dajbych, Petr Hrabě and Čestmír Mizera

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.

Open access

Cestmir Mizera, David Herak, Petr Hrabe and Abraham Kabutey

Abstract

The mechanical behaviour of natural fibres as composite materials can be affected by changes in temperature and moisture content. The aim of this paper was to describe the effect of temperature and moisture content on tensile strength of false banana fibre (Ensete ventricosum) and to determine its water absorption. Samples of fibres were prepared and tested until rupture point with strain rate of 0.05 min−1 at temperature change between −20 and 220°C as well as moisture content between 10 and 90% wb. The water absorption and release of Ensete fibres at 60 and 90% relative humidity was also determined. Results showed that Ensete fibres exhibited stability of tensile strength in the temperature range from 0 to 100°C but the increase of temperature decreased statistically significantly the tensile strength. The effect of moisture content on tensile strength was not statistically significant. The equilibrium moisture content at 60% relative humidity and 25°C was determined.