ARID ZONE JOURNAL OF ENGINEERING, TECHNOLOGY & ENVIRONMENT AZOJETE June 2023. Vol. 19(2):271-288 Published by the Faculty of Engineering, University of Maiduguri, Maiduguri, Nigeria. Print ISSN: 1596-2490, Electronic ISSN: 2545-5818 www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 271 ORIGINAL RESEARCH ARTICLE DEVELOPMENT AND PERFORMANCE EVALUATION OF A MOTORIZED TIGERNUT OIL EXTRACTION MACHINE P. A. Omale1*, A. K. Aremu2, M. O. Omobowale2 1Department of Agricultural and Environmental Engineering, Joseph Sarwuan Tarka University, Makurdi, Benue State, Nigeria. 2Department of Agricultural and Environmental Engineering, University of Ibadan, Ibadan, Oyo State, Nigeria *Corresponding author’s email address: omale.paul@uam.edu.ng 1.0 Introduction The extraction of oil from oil seeds and nuts such as cotton, soyabean, olive, corn, mustard seed, palm tree, coconut, carrot, groundnut, sunflower seed, rapeseed, sesame, castor seed etc. across the globe is a common practice and have played a significant part in human diet as source of fat and oil (Aremu and Ogunlade, 2016, Akomaye and Fehintola, 2019). The oil extracted from these oil seeds and nuts are applied in different areas and for different purposes such as food nutrients, cosmetics, medications, Biodiesel, paints (Samaila and Chukwu, 2014, Omale and Omobowale, 2018, Yusuf, 2018). The extensive range of applications for vegetable oil and the high demand in society attract researchers to explore and uncover new oil seeds. Bamgboye and Adejumo (2011) emphasized the vital role of oil extraction in oil seed processing, highlighting its significance in terms of quality and quantity. They also noted that extraction methods include chemical, mechanical, and traditional approaches. Various extraction methods have different oil yield which can be improved upon by optimizing the extraction conditions (Divine and Anuanwen, 2020, Naquib and Faisal, 2020). ARTICLE INFORMATION ABSTRACT Tiger nut is a common nut in Africa which contains 24.5% oil. The extraction of this oil has been a major challenge to developing countries as most oil is locally extracted because of high cost of importation of oil expellers. A motorized tiger nut oil extracting machine was designed and fabricated consisting of four sections namely feeding, extraction, heating and power sections using available local materials, and was evaluated and optimized. The oil yield (OY), operational rate (OR), extraction efficiency (EE), throughput capacity (TC) and extraction loss (EL) of the machine were determined as affected by barrel temperatures (BT) of 30°C, 45°C, 60°C range, screw speeds (SS) of 60 rpm, 75 rpm, 90 rpm range., 0.5 mm, 1 mm, 1.5 mm range of choke clearance (CC) of the machine and yellow/brown varieties of tiger nut. The optimum ER, EE, OY, EL and TC values of 9.93 kg/hr., 89.02%, 23.78%, 1 kg/hr. and 50.06 kg/hr. were achieved at 60°C barrel temperature, 60 rpm and 0.5 mm choke clearance while the lowest values gotten at 30°C barrel temperature, 90 rpm and 1.5 mm choke clearance were 6.33 kg/hr., 52.40%, 13.90%, 0.33 kg/hr. and 33.96 kg/hr. respectively. Analysis of variance revealed that barrel temperature, screw speed, choke clearance and variety have significant effects on all the machine parameters evaluated at p<0.05 except for the EL. The evaluation results revealed that the brown tiger nut has more oil than the yellow tiger nut and that the developed machine is deemed efficient for small scale tiger nut oil production. © 2023 Faculty of Engineering, University of Maiduguri, Nigeria. All rights reserved. Submitted 7 February, 2023 Revised 5 March, 2023 Accepted 6 March, 2023 Keywords: Development Extraction Efficiency Tiger nut Oil http://www.azojete.com.ng/ mailto:williamolosunde@uniuyo.edu.ng mailto:%20omale.paul@uam.edu.ng Arid Zone Journal of Engineering, Technology and Environment, June, 2023; Vol. 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818; www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 272 Africa is reported to have produced several oil seeds, with oil palm, groundnut, soybeans, and cotton topping the list as observed by Boadi et al. (2022) where many other oil seeds and nuts have not been utilized such as tiger nut are in abundance. Yet, the demand of vegetable oil in Africa (especially Nigeria) is more than its supply as such, causes constant increase in the price of available vegetable oil. Tiger-nut (Cyperus esculentus L) is a grass like root plant that is rich in nutrients needed by both human and animal. It is cultivated in many African countries including northern Nigeria (Omale et al., 2020). Tiger nut has 24.5% oil (Zhen-shan et al., 2022). It has different varieties and have different names by different ethnic groups. It is generally known in Nigeria as “Aya” in Hausa, “Ofio” in Yoruba, “Akiausa” in Igbo and “Shoho” (Awulu et al., 2018 and Omale et al., 2020). Itcontains golden brown oil which is consumable compared to several other vegetable oil because of its nutritional quality (Yali et al., 2022, Ezebor et al., 2005). However, the manual process of extracting the oil from tiger nuts is time-consuming and labor-intensive. Bamgboye and Adejumo (2007) and Olayanju et al. (2006) found that the traditional extraction method is widely used in Africa due to expensive imports of oil expeller and screw press, resulting in slow, tedious, time- consuming, and demotivating oil extraction processes. In an effort to improve efficiency and increase production, the development and performance evaluation of a motorized tiger nut oil extraction machine was undertaken. This machine is expected to revolutionize the tiger nut oil extraction industry, offering faster and more efficient oil extraction potential. 2 Methodology 2.1 Design Conception The developed tiger nut oil extraction machine has five main components: the feeding, extraction, power, heating, and the frame components. The feeding section is made up of stainless-steel hopper, while the extraction section has a screw shaft, barrel, barrel guide, cake collector, oil collector, and choke. The power section has an electric motor, gear box, belt, and pulleys. The heating section has a heating element, temperature sensor, and control panel, and the frame supports the other parts. Plate 1 shows the pictorial view of the machine while Figures 1, 2, and 3 show the machine's isometric drawing, exploded drawing, and orthographic drawing, respectively. 2.2 Design Consideration The utmost consideration was given to the tiger nut's engineering properties, availability, durability, strength, corrosion resistance, and safety of construction materials, as well as overall cost. 2.3 Design of Machine Components 2.3.1 Design of the Hopper The hopper was made with a stainless-steel material. The passing hole of the hopper was designed to be sizeable enough to avoid choking of the materials using a mass flow pattern as described by Khurmi and Gupta (2008). The volume of the hopper was calculated using equation 1: file:///C:/user/Downloads/azojete143/www.azojete.com.ng Omale et al: Development and Performance Evaluation of a Motorized Tigernut Oil Extraction Machine. AZOJETE, 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 273 𝑉 = 1 3 × ℎ × (𝑎2 + 𝑏2 + 𝑎𝑏) (1) where: V = volume, h = height of the Hopper, a = length of the larger base, b = length of the smaller base 2.3.2 Belt drive design A rubber V-Belt was used to transmit power from the prime mover to the screw shaft by means of pulleys. 2.3.3 Selection of the pulleys of the machine The diameters of the pulleys were selected considering the speeds (in revolutions per minute) to be transmitted between the electric motor and the screw (worm) shaft. The diameters of the pulleys were calculated using equation 2 as given by Khurmi and Gupta (2008): 𝑁1𝐷1 = 𝑁2𝐷2 (2) where: N1 = Speed of the electric motor (rpm), N2= Speed of the screw shaft, (rpm), D1= diameter of the electric motor pulley (mm), D2= pulley diameter of screw shaft 2.3.3.1 Distance between pulley centre The distance between pulley centre was calculated from equation 3 (Cleghorn and Nikolai, 2015). 𝑋 = 𝐶2 + ((𝑅1 + 𝑅2) − (2𝑅1𝑅2cos Ɵ))0.5 (3) where: X is the distance between the centers of the pulleys, C is the distance between the axes of the pulleys, R1 and R2 are the radii of the two pulleys, and theta is the angle between the belts as they wrap around the pulleys. 2.3.4 Belt length According to Shigley et al. (2011), the length of an open belt drive is given by. Belt Length (L) = 2X + π 2 (d1 + d2 ) + (d2−d1)2 4X (4) where: X = Distance between pulleys centre (mm), d1= Driver (electric motor) pulley diameter (mm), d2 = Driven (Screw shaft) pulley diameter (mm). 2.3.5 Design of the screw shaft of the oil extraction machine The screw shaft is the major oil extraction part of the tiger nut oil extraction machine and acted upon by the material weight, pulley, and screw flights. When in use, the screw shaft conveys, press and squeeze the biomaterial for oil extraction. 2.3.5.1 Diameter of the worm shaft To safeguard against bending and tensional stresses, the shaft diameter was estimated from equation 5 (Callister et al., (2018; Khurmi and Gupta, 2008; Adesoji et al., 2012). http://www.azojete.com.ng/ mailto:%20omale.paul@uam.edu.ng Arid Zone Journal of Engineering, Technology and Environment, June, 2023; Vol. 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818; www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 274 ds 3 = 16T 0.27πδ0 (5) where: ds = Diameter of the screw shaft, T = Torque transmitted by the shaft (Nm) and Δ0 = Yield stress for stainless steel (N/mm2). 2.3.5.2 Estimation of the pitches of the decreasing pitch screw conveyor The inlet velocity of raw material (V) was estimated from Equation 6 (Jones and Kocher, 1995). V = Ps × π 4 (𝐷2 − 𝑑2)N 4DL (6) where: V = Inlet velocity (mm/s), Ps = Screw pitch (mm), D = Outside diameter of screw (mm), d = Inside diameter of screw (mm), L = Length of the screw shaft (mm), N = Shaft speed (rpm). 2.3.5.3 The screw winding length The screw winding length (L) was estimated applying Pythagoras rule as the square root of the sum of squares of the circumference (C) of the shaft diameter and the screw pitch (Ps) (Omote and Mwangi, 2012) as given in Equation 7. L = √C2 − Ps 2 (7) The circumference of the shaft diameter = πd (mm) 2.3.5.4 Axes of flight screw distance Axes of flight screw distance was estimated applying the relation shown in Equation 8 (Fadeyibi et al., 2016). a Ds ≤ √2 2 (8) where: a = flight axis distance (mm), Ds = barrel diameter (mm). 2.3.5.5 Maximum flight height Maximum flight height (channel depth) (hmax) was estimated following the equation reported by Fadeyibi et al. (2016) as. hmax = Ds − a (9) where: hmax = Maximum height of flight (mm), Ds = Barrel diameter (mm), a = flight axis distance (mm) 2.3.5.6 Helix angle (Pitch angle) The helix angle (angle of pitch) at the barrel surface (α), which is associated to lead, and diameter was estimated applying equation 10 (Fadeyibi et al., 2016). file:///C:/user/Downloads/azojete143/www.azojete.com.ng Omale et al: Development and Performance Evaluation of a Motorized Tigernut Oil Extraction Machine. AZOJETE, 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 275 α = tan−1 ( P πDs ) (10) where: α = Helix angle (o), P = Mean screw pitch (lead) (mm), Ds = Barrel diameter (mm). 2.3.6 Pressurized Cone (choke) The choke was conical in shape and made of stainless-steel material which was attached to the shaft at the end of the screw flight to effectively pressurize the tiger nut. The linear movement of the worm shaft was controlled by adjustable nuts that estimate the extraction ratio. The weight of the choke was calculated from Equations 11 and 12 (Hannah and Hillier, 1999). Weight of choke = density × (Volume of cone – Volume of bore) (11) W = ρ × ( 1 3 π(R2 + r2 + Rr)h − πr2h) (12) where: W = Weight of choke (kg), ρ = Density of stainless steel (kg/m3), R = Bigger radius of conical choke (mm), r = Smaller radius of conical choke (h) = height of conical choke (mm). 2.3.7 Press cage (barrel) design The press cage (barrel) was designed to have a large hole for feeding oil bearing material. This feeding hole was machined at the beginning of the screw shaft where the screw pitch was maximum. On the mid zone, the barrel has an oil outlet sieve. The inner diameter of the press cage was determined from Equation 13 (Olaniyan, 2010). DI = D + 2C (13) where: DI = Inner diameter of the press cage, D = Screw shaft diameter (mm), C = Clearance between the internal wall of press cage and screw thread (mm). The outer diameter of the press cage was estimated using equation 14 (Olaniyan, 2010). DI = 0.95 D0 (14) where: D0 = Outer diameter of the press cage in mm. The thickness (t) of the press cage was determined from equation 15 (Olaniyan, 2010). t = D0 − DI (15) 2.3.8 Screw press power requirement The design of the tiger nut oil extraction machine considered the entire areas where power is needed such as power to overcome the inertia of the screw shaft, power to drive and convey the tiger nut through the entire length of the press, power to effectively press and squeeze out entrapped oil from the tiger nut and power compensation for friction and heat losses during operation. 2,982 Watts power was designed for to run the developed machine. http://www.azojete.com.ng/ mailto:%20omale.paul@uam.edu.ng Arid Zone Journal of Engineering, Technology and Environment, June, 2023; Vol. 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818; www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 276 2.3.9 Design of machine frame The frame was designed to avoid failure of the beam by bending and the column by buckling by considering the entire weight of components and constructed with mild steel material. 2.4 Machine Description The isometric drawing, pictorial view, exploded views and orthographic projections of the machine assembly are presented in Figures 1 to 4. Figure 1: Isometric drawing of the tiger nut oil extraction machine Figure 2: Pictorial view of the machine Figure 3: Exploded drawing of a motorized tiger nut oil extracting machine file:///C:/user/Downloads/azojete143/www.azojete.com.ng Omale et al: Development and Performance Evaluation of a Motorized Tigernut Oil Extraction Machine. AZOJETE, 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 277 Figure 4: Orthographic drawing of a motorized tiger nut oil extracting machine 3 Performance Evaluation The developed machine’s throughput capacity, extraction rate, oil yield, extraction efficiency and extraction loss as affected by different machine parameters such as choke clearances (0.5mm, 1mm and 1.5mm), shaft speeds (60rpm, 75rpm and 90rpm), Barrel temperature (30°C, 45°C and 60°C) and variety (brown and yellow) were evaluated by operating the machine at different speeds, choke clearances and barrel temperatures respectively for tiger nut oil extraction. 3.1 Determination of the throughput capacity This is the machine's capability in terms of quantity of tiger nut it processes per unit time. It was quantified using the relationship according to Adesoji et al. (2012) given in Equation 16: OR = WFS T (16) where: OR = Rate of operation (kg/hr), WFS = Weight of fed sample (kg), T = Operation time (hr). 3.2 Determination of the extraction rate Extraction rate is the weight of oil that the machine could bring out per unit time (Adesoji et al., 2012) and this was calculated applying Equation 17. ER = Wo T (17) where: ER = Extraction rate (kg/hr), WO = Weight of oil extract (kg), T = Operation time (hr). http://www.azojete.com.ng/ mailto:%20omale.paul@uam.edu.ng Arid Zone Journal of Engineering, Technology and Environment, June, 2023; Vol. 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818; www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 278 3.3 Determination of the oil yield The extraction oil yield was expressed as the percentage fraction of the mass of extracted oil to the mass of pressed tiger nut sample. Tiger nut oil yield was calculated using the Equation 18 stated by Olaniyan and Oje (2011) and Adesoji et al. (2012) as: OY = 100 WOE WOE+WRC (18) where: OY = Oil yield (%), WOE = Weight of oil extracted (kg), WRC = Weight of residual cake (kg). 3.4 Estimation of extraction efficiency The extraction efficiency of the machine was evaluated by expressing the oil extracted as a percentage of the total oil content of the tiger nut samples. This was calculated using Equation 19 (Olaniyan and Oje, 2011; Adesoji et al., 2012). OE = 100 WOE XWFS (19) where: OE = Extraction efficiency (%), WOE = Weight of oil extracted (kg), WFS = Weight of fed sample (kg) and X = Oil content of tiger nut in decimal. 3.5 Determination of extraction loss Extraction loss is the fraction of the unrecovered sample to the fed sample. This was estimated according to Olaniyan and Oje (2011) and Adesoji et al., (2012) using Equation 20: EL = 100[WFS− (WOE+WRC)] WFS (20) where: EL = Extraction loss (%), WFS = Weight of fed sample (kg), WOE = Weight of oil extracted (kg), WRC = Weight of residual cake (kg). 4 Results and Discussion 4.1 Extraction rate The oil extraction rate of the brown tiger nut ranged from 6.3312 - 9.9300 (kg/hr) while that of the yellow tiger nut ranged from 6.4708 -9.4070 (kg/hr) as shown in Figure 5. It was observed that the least extraction rate for the brown tiger nut was achieved when the machine was set to 30°C barrel temperature, speed of 90 rpm and choke clearance of 1.5mm and that of yellow tiger nut was gotten at 60°C barrel temperature, 90 rpm and 1.5 mm choke clearance. The highest extraction rate for both the brown and yellow tiger nut were obtained at 45°C barrel temperature, 60 rpm speed and 0.5 mm choke clearance. Analysis of variance revealed that tiger nut variety, barrel temperature, screw speed and choke clearance all have significant effects on the extraction rate of the developed machine at p < 0.05. The extraction rate was observed to increase as the choke clearance decreases and the speed and barrel temperature increases respectively. file:///C:/user/Downloads/azojete143/www.azojete.com.ng Omale et al: Development and Performance Evaluation of a Motorized Tigernut Oil Extraction Machine. AZOJETE, 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 279 Figure 5: Extraction Rate results of the Machine 4.2 Extraction Efficiency The extraction efficiency of brown tiger nut was found to be between 53.6616% and 90.22778% while that of yellow tiger nut was between 52.3990% and 89.0152% (Figure 6). It was observed that the lowest extraction efficiency for brown tiger nut was obtained at 60°C barrel temperature, 90 rpm speed, and 1.5mm choke clearance, and for yellow tiger nut it was also obtained at 60°C barrel temperature, 90 rpm speed, and 1.5mm choke clearance. The highest extraction efficiency for both brown and yellow tiger nut was obtained at 45°C barrel temperature, 60 rpm speed, and 0.5mm choke clearance, respectively. Analysis showed that the tiger nut variety, barrel temperature, screw speed, and choke clearance all have a significant impact on the extraction efficiency (p < 0.05) as shown on Table 1. The efficiency was found to decrease as choke clearance and speed decreased and as barrel temperature increased. 0 2 4 6 8 10 12 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 60 rpm 75 rpm 90 rpm 60 rpm 75 rpm 90 rpm 60 rpm 75 rpm 90 rpm 30°C 45°C 60°C Ex tr ac ti o n R at e (k g/ h r) Barrel Temperature (°C) Brown tiger nut Yellow tiger nut http://www.azojete.com.ng/ mailto:%20omale.paul@uam.edu.ng Arid Zone Journal of Engineering, Technology and Environment, June, 2023; Vol. 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818; www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 280 Figure 6: Extraction Efficiency of the Machine 0 10 20 30 40 50 60 70 80 90 100 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 60 rpm 75 rpm 90 rpm 60 rpm 75 rpm 90 rpm 60 rpm 75 rpm 90 rpm 30°C 45°C 60°C Ex tr ac ti o n E ff ic ie n cy ( % ) Barrel Temperature (°C) Brown tiger nut Yellow tiger nut file:///C:/user/Downloads/azojete143/www.azojete.com.ng Omale et al: Development and Performance Evaluation of a Motorized Tigernut Oil Extraction Machine. AZOJETE, 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 281 Table 1: ANOVA Result of the Machine evaluation Tests of Between-Subjects Effects Source Dependent Variable Type III Sum of Squares df Mean Square F Sig. Variety Weight of Cake .012 1 .012 107.884 <.001 Weight of Oil .011 1 .011 93.593 <.001 Operation Time 7.697E-5 1 7.697E-5 49.330 <.001 Extraction Rate .846 1 .846 6.203 .014 Extraction Efficiency 391.670 1 391.670 93.593 <.001 Oil Yield 27.945 1 27.945 99.619 <.001 Extraction Loss .020 1 .020 .286 .594 Throughput Capacity 43.736 1 43.736 32.209 <.001 Barrel Temperature Weight of Cake .008 2 .004 37.324 <.001 Weight of Oil .010 2 .005 44.228 <.001 Operation Time .001 2 .000 254.714 <.001 Extraction Rate 5.468 2 2.734 20.046 <.001 Extraction Efficiency 370.170 2 185.085 44.228 <.001 Oil Yield 24.875 2 12.438 44.339 <.001 Extraction Loss .668 2 .334 4.770 .010 Throughput Capacity 569.860 2 284.930 209.833 <.001 Screw Speed Weight of Cake .104 2 .052 485.451 <.001 Weight of Oil .103 2 .051 439.513 <.001 Operation Time 7.421E-5 2 3.711E-5 23.780 <.001 Extraction Rate 34.523 2 17.262 126.558 <.001 Extraction Efficiency 3678.586 2 1839.293 439.513 <.001 Oil Yield 260.172 2 130.086 463.744 <.001 Extraction Loss .334 2 .167 2.389 .097 Throughput Capacity 52.439 2 26.220 19.309 <.001 Choke Clearance Weight of Cake .308 2 .154 1440.226 <.001 Weight of Oil .305 2 .152 1305.339 <.001 Operation Time .002 2 .001 488.747 <.001 Extraction Rate 28.153 2 14.077 103.206 <.001 Extraction Efficiency 10925.269 2 5462.634 1305.339 <.001 Oil Yield 773.140 2 386.570 1378.083 <.001 Extraction Loss .049 2 .025 .352 .704 Throughput Capacity 1205.484 2 602.742 443.882 <.001 Error Weight of Cake .012 108 .000 Weight of Oil .013 108 .000 Operation Time .000 108 1.560E-6 Extraction Rate 14.730 108 .136 Extraction Efficiency 451.963 108 4.185 Oil Yield 30.295 108 .281 Extraction Loss 7.560 108 .070 Throughput Capacity 146.652 108 1.358 a. R Squared = .977 (Adjusted R Squared = .965) b. R Squared = .974 (Adjusted R Squared = .962) c. R Squared = .955 (Adjusted R Squared = .933) d. R Squared = .893 (Adjusted R Squared = .841) http://www.azojete.com.ng/ mailto:%20omale.paul@uam.edu.ng Arid Zone Journal of Engineering, Technology and Environment, June, 2023; Vol. 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818; www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 282 4.3 Oil Yield The oil yield of brown tiger nuts ranged from 14.2615% to 24.033%, while the yield of yellow tiger nuts ranged from 13.9028% to 23.6181%, as shown in Figure 7. It was noted that the lowest oil yields for both types of tiger nuts were obtained when the machine was set at 60°C barrel temperature, a speed of 90 RPM, and a choke clearance of 1.5mm. The highest oil yield for brown tiger nuts was obtained at 45°C barrel temperature, 90 RPM speed, and 0.5mm choke clearance, and for yellow tiger nuts, it was obtained at 45°C barrel temperature, 60 RPM speed, and 0.5mm choke clearance. An analysis of variance revealed that the tiger nut variety, barrel temperature, screw speed, and choke clearance all significantly impacted the oil yield of the machine, with p < 0.05. This aligns with the findings reported by Aremu and Ogunlade (2016) in their study of African oil bean seeds. The oil yield decreases as the choke clearance and speed increases but increases as the barrel temperature increases and this is because increased choke clearance and speed in an oil extraction machine reduce oil yield due to limited contact time, hindering efficient extraction. Conversely, higher barrel temperature improves oil yield by enhancing fluidity, reducing viscosity, and increasing solubility and separation, facilitating oil extraction. e. R Squared = .974 (Adjusted R Squared = .962) f. R Squared = .976 (Adjusted R Squared = .964) g. R Squared = .321 (Adjusted R Squared = -.012) h. R Squared = .949 (Adjusted R Squared = .924) file:///C:/user/Downloads/azojete143/www.azojete.com.ng Omale et al: Development and Performance Evaluation of a Motorized Tigernut Oil Extraction Machine. AZOJETE, 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 283 Figure 7: Oil Yield of the Machine 4.4 Extraction Loss The extraction loss of brown tiger nuts varied from 0.5 to 1 kg/hr, while that of yellow tiger nuts ranged from 0 to 0.8333 kg/hr, as depicted in Table 2. It was noted that the lowest extraction loss for brown tiger nuts was achieved with a machine set at 30°C barrel temperature, 90 rpm speed, and choke clearance of 1.5mm, 1mm, and 0.5mm. For yellow tiger nuts, the lowest extraction loss was obtained at 60°C barrel temperature, 90 rpm speed, and 1.5mm choke clearance. The highest extraction loss for brown tiger nuts was achieved at 45°C barrel temperature, 90 rpm speed, and 1.5mm choke clearance, while the highest extraction loss for yellow tiger nuts was obtained at 45°C barrel temperature, 90 rpm speed, and 1.5mm choke clearance. Analysis showed that the factors of tiger nut variety, barrel temperature, screw speed, and choke clearance all had no significant impact (p < 0.05) on the extraction loss of the machine. The extraction loss increased as the barrel temperature, speed, and choke clearance increased, which is in line with the findings reported by Ishola et al. (2022). 0 5 10 15 20 25 30 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 0 .5 m m 1 m m 1 .5 m m 60 rpm 75 rpm 90 rpm 60 rpm 75 rpm 90 rpm 60 rpm 75 rpm 90 rpm 30°C 45°C 60°C O il Yi el d ( % ) Barrel Temperature (°C) Brown tiger nut Yellow tiger nut http://www.azojete.com.ng/ mailto:%20omale.paul@uam.edu.ng Arid Zone Journal of Engineering, Technology and Environment, June, 2023; Vol. 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818; www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 284 Table 2: Results of the Extraction Loss of the Machine 4.5 Throughput Capacity Table 3 shows the throughput capacity of the developed machine to extract tiger nut oil varied between 33.9683 and 49.3333 kg/hr for brown tiger nuts and 36.7424 to 50.0580 kg/hr for yellow tiger nuts. The lowest processing throughput capacity for both types of tiger nuts was observed when the machine was set at a barrel temperature of 30°C, a speed of 60 rpm, and a choke clearance of 0.5 mm. The highest extraction throughput capacity for both brown and yellow tiger nuts was achieved at a barrel temperature of 60°C, a speed of 75 rpm, and a choke clearance of 1.5 mm. the analysis further showed that variety of tiger nut, barrel temperature, screw speed, and choke clearance significantly impacted the processing throughput capacity of the machine. In addition, an increase in choke clearance, barrel temperature, and speed leading to an increase in throughput capacity. Brown Tigernut Yellow Tigernut Barrel Temp. (°C) Speed (rpm) Choke clearance (mm) Extraction Loss (kg/hr) Std. Deviation Extraction Loss (kg/hr) Std. Deviation 30 60 0.5a .6667 .28868 .6667 .28868 1a .6667 .28868 .5000 .00000 1.5a .5000 .00000 .5000 .00000 75 0.5 .8333 .28868 .6667 .28868 1 .5000 .50000 .6667 .28868 1.5 .6667 .28868 .6667 .28868 90 0.5 .6000 .17321 .5000 .00000 1 .3333 .28868 .6667 .28868 1.5 .6667 .28868 .5000 .00000 45 60 0.5 .3333 .28868 .6667 .28868 1 .3333 .28868 .5000 .00000 1.5 .6667 .28868 .5000 .00000 75 0.5 .6667 .28868 .6667 .28868 1 .8333 .28868 .5000 .00000 1.5 .6667 .28868 .5000 .00000 90 0.5 .6667 .28868 .5000 .00000 1 .5000 .00000 .6667 .28868 1.5 .5000 .50000 .6667 .28868 60 60 0.5 1.1667 .28868 .5000 .00000 1 .8333 .28868 .8333 .28868 1.5 .6667 .28868 .6667 .28868 75 0.5 .6667 .28868 .6667 .28868 1 .6667 .28868 .6667 .28868 1.5 1.0000 .00000 .8333 .28868 90 0.5 .6667 .28868 .8333 .28868 1 .6667 .28868 .6667 .28868 1.5 .6667 .28868 .5000 .00000 file:///C:/user/Downloads/azojete143/www.azojete.com.ng Omale et al: Development and Performance Evaluation of a Motorized Tigernut Oil Extraction Machine. AZOJETE, 19(2):271-288. ISSN 1596-2490; e-ISSN 2545-5818, www.azojete.com.ng Corresponding author’s e-mail address: omale.paul@uam.edu.ng 285 Table 3: Results of the Throughput Capacity of the Machine 5 Conclusion A motorized tiger nut oil extraction machine was developed and evaluated to provide an economic means of processing oil from tiger nuts. The main aim of developing the machine is to provide the most economical means for processing oil from tiger nut. The machine achieved optimum extraction parameters at 45°C barrel temperature, 60rpm speed, and 0.5 choke clearance, resulting in a throughput capacity of 9.9kg/hr, 90.23% extraction efficiency, 24.032% oil yield, and 1kg/hr extraction loss. Lower values were obtained at 30°C barrel temperature, 90rpm speed, and 1.5 choke clearance. Analysis of variance revealed that barrel temperature, screw speed, choke clearance and variety have significant impacts on all the machine evaluated parameters at p≤0.05 except for the extraction loss. It is confirmed that the brown tiger nut has more oil than the yellow tiger nut and the developed machine is efficient for small scale tiger nut oil production. Brown Tigernut Yellow Tigernut Variety Barrel Temp. (°C) Speed (rpm) Choke clearance (mm) Throughput Capacity (kg/hr) Std. Deviation Throughput Capacity (kg/hr) Std. Deviation 30a 60a 0.5a 33.9683 .54986 36.7424 .65608 1b 42.8936 1.53289 41.8719 .85323 1.5c 46.1538 .00000 46.7692 1.06588 75a 0.5 34.6218 .58220 37.9032 .69841 1 38.7366 1.25022 45.0142 .98692 1.5 34.3044 .98053 45.5840 .98692 90b 0.5 36.7424 .65608 38.7097 .00000 1 40.9195 .79635 40.0297 1.33506 1.5 39.5699 .74497 44.4444 .00000 45b 60 0.5 37.5244 1.17321 38.7366 1.25022 1 42.8936 1.53289 42.3645 .85323 1.5 45.0142 .98692 41.8719 .85323 75 0.5 37.9032 .69841 38.7366 1.25022 1 40.4598 .79635 45.0142 .98692 1.5 43.3862 .91643 50.0580 2.08756 90 0.5 38.7366 1.25022 39.5699 .74497 1 46.1994 1.77822 45.0142 .98692 1.5 48.6667 1.15470 50.0580 2.08756 60c 60 0.5 40.9195 .79635 40.0297 1.33506 1 42.3645 .85323 45.5840 .98692 1.5 48.6667 1.15470 47.3846 1.06588 75 0.5 44.4851 1.64873 40.0297 1.33506 1 44.4851 1.64873 43.9153 .91643 1.5 49.3333 1.15470 46.1994 1.77822 90 0.5 44.4851 1.64873 42.8936 1.53289 1 48.0513 1.92359 45.0142 .98692 1.5 46.7692 1.06588 46.7692 1.06588 http://www.azojete.com.ng/ mailto:%20omale.paul@uam.edu.ng Arid Zone Journal of Engineering, Technology and Environment, June, 2023; Vol. 19(2):271-288. 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