Determination of Rotor Operating Factor (Efficiency) Required for the Design of Rotor Speed in a Centrifugal Nut Cracker (original) (raw)
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Experimental Determination of the Rotor Speed of a Vertical Shaft Centrifugal Nut Cracking Machine
The impinging velocitythat gives that maximum cracking efficiency of a vertical shaft centrifugal palm nut cracking machine was determined in this study. A nut cracking energy instrument which consists of a hammering mass falling vertically on palm nuts placed on a base was used to determine potential energy required to crack the nuts. This energy was equated to the kinetic energy required to crack the nuts in a centrifugal palm nut cracking machine, from which the average impinging velocity was determined. Experiment was carried out to generate cracking energy data for both Dura and Tenera varieties of palm nuts available in the study area. For Dura type, highest percentage of fully cracked (FC) nuts and average impinging velocity of 32.50 m/s were obtained when the height of the hammering mass was set at 0.15m, 0.25m and 0.30m for nuts sorted into diameter ranges of d < 15mm, 15mm ≤ d ≤ 18mm, and 18mm ≤ d ≤ 22mm respectively. For the Tenera type, highest percentage of fully cra...
Rotor to Drum Diameter Ratio Required for Effective Cracking of Palm Nut in Centrifugal Cracker
ABSTRACT: The estimation of a favourable ratio of rotor diameter to cracking drum diameter that would enhance effective delivery and cracking of nuts to yield high percentage of whole kernels was carried out. In this study, dried palm nuts 4.88 % wb of mixed variety (Dura and Tenera) were classified into five size ranges based on nut geometric mean diameter. Seven diameter ratios were chosen. Each rotor diameter to drum diameter ratio was run at seven speeds. For each speed each nut size range was subjected to impact on the cracking drum surface of a Test Rig (centrifugal nut cracker). The nuts were assessed after impact. Result showed that rotor diameter to cracking drum diameter ratios of 0.22, 0.33 and 0.67 enhanced effectively the cracking of palm nuts to yield high release of whole kernels. Economical production of high percentage of whole kernel using centrifugal nut cracker tends to favour rotor diameter to cracking drum diameter of 0.67 and speed of 31 m/s.
Research in Agricultural Engineering
A mathematical model for predicting the cracking efficiency of vertical-shaft palm nut cracker was presented using dimensional analysis based on the Buckingham’s π theorem. A high coefficient of determination of 94.3% between the predicted and measured values showed that the method is good. The model was validated with data from existing palm nut cracker and there was no significant difference between the experimental cracking efficiency with the predicted values at 5% level of significance. Keywords: cracking efficiency; prediction equation; feed rate; throughput capacity; shaft speed; dimensional analysis The modern crackers are of two types; the hammer impact and the centrifugal impact types. The hammer impact type breaks or cracks the nut on impact when the hammer falls on it; while centrifugal impact nut cracker uses centrifugal action to crack the nut (Ndukwu, Asoegwu 2010). In the centrifugal impact type; the nut is fed into the hopper and it falls into the housing where a pl...
Dynamics of Centrifugal Impact Nut Cracker
This paper presents the dynamics of vertical axis centrifugal nut cracker. The cracker consists of a feed hopper with a flow rate control device, cracking unit, separating unit and power system which consists of a single phase 3hp, 1500-rpm electric motor with belt and pulley system. The cracking unit consists of impeller with four vanes mounted on a vertical shaft and an impeller casing which served as the cracking surface. The working principle of the cracker is similar to that of centrifugal pump. The nuts to be cracked are rotated and pushed by the vanes of the impeller in the direction of the vanes motion, thereby imparting mechanical energy to the nuts. The direction of motion of nuts through the impeller is radially outward. When leaving the impeller, the nuts gain kinetic (velocity) energy and the velocity components are studied graphically by means of velocity vectors. The results of the analysis showed that the radial velocity is 0.66 m/s, tangential velocity is 15.71 m/s, resultant velocity is 15.72 m/s, while the cracking velocity is 10.41 m/s which gave an impact (cracking) energy of 0.55 J. The cracker was evaluated using sheanut at four moisture levels of 6, 13, 22.7 and 27.9% (db) and nut feed rates of 11.4, 15.5, 23.1 and 45.2 kg/h. The study showed that at nut moisture content of 22.7% (db) and feed rate of 11.4 kg/h, the cracking efficiency of 100% was achieved.
Development and performance evaluation of palm nut cracker
2019
In this paper, palm nut cracking machine was designed, fabricated and the performance evaluation done using locally sourced materials. The cracking machine was developed to have the hopper, the cracking chamber which incorporates the shaft and cracking hammers, the outlet, electric motor, belt and pulleys. The performance of the machine was evaluated to consider the cracking time, the shaft speed and the throughput. At shaft speed of 800 rpm, the average cracking time and throughput values are 86.14 s and 11.606 g/s, respectively for 1 kg of palm kernel nuts. The average cracking time and throughput values at 1200 rpm and 1400 rpm are 59.54 s and 16.799 g/s, and 47.58 s and 21.061 g/s, respectively. The results obtained show that as the shaft speed increases, the cracking time reduces and throughput increases. The efficiency of the machine is averagely estimated to be 74.2%. The throughput of the machine is determined to be 75.6kg nuts/ hour. This mechanized system of cracking is fa...
Properties influencing cracking and separation of palm nuts in a mechanical cracker.pdf
Croatian Journal of Food Science and Technology, 2018
Experimental studies of some properties influencing cracking and separation of palm kernel from the shell was conducted in a palm kernel dual processing machine. A mechanical cracking cum separating machine was developed for the study. The cracking unit consists of feed hopper, impeller shaft, cracking drum and impeller blade. The nut falls by gravity through the hopper channel into the cracking drum where the cracking process takes place through the help of impeller blades that flip the palm nut against the walls of cylindrical cracking drum. The mass of cracked nut flows through the separating unit that separates the kernel from the shell. The separation is induced by high current of air mass generated by an axial fan. A dura palm variety was selected and a total sample of eighteen thousand (18000) palm nuts were obtained and divided into two groups (feed rates), A and B, of eight thousand and ten thousand palm nuts respectively. Sample groups A and B were further divided into five sub – groups of four hundred (400) and five hundred (500) palm kernel nuts. Each sub group (feed rate) was replicated four times at different shaft speeds (600, 900, 1200, 1500 and 1800 rpm). Results showed that cracking efficiencies increased with respect to speed. Un-cracked nuts percentage ranged from 1.3 to 5.3% at 7.1% moisture content, and 1.6 to 4.5% for 400 and 500 feed rates, respectively. Cracking time for both feed rates decreased with shaft speed. Throughput capacity of 11.49 kg/h was observed to be the lowest at 600 rpm and moisture content of 7.1% for both 400 feed rates and the highest throughput capacity of 37.16 kg/h was recorded at 1800 rpm at moisture contents of 9.3% and 16.1%. The results of this study shows that moisture content, engine speed and feed rate are significant parameters that influence cracking of nuts and separation of palm kernel from the shell.
Thesis : Nut Cracking Efficiency in Palm Oil Mill
The case study was carried out at Kilang Minyak Sawit Kamunting Sdn.Bhd,Taiping aiming towards increasing the production of palm oil. This could be achievedby improving the ripple mill machine. The ripple mill machine is part of the palm oil factory and is used to separate the palm kernel and its shell. The scope of the study is to investigate the efficiency of palm kernels and shell breakage. The efficiency could be increased by improving the existing machine. Based on the design of the existing ripple mill machine, the ripple rod has shorter shelf life due to bending of the rod. Among the parameters that is expected to affect the efficiency of the palm kernels and shell breakage and bending of the rods are the optimum speed of the rotor, the distance between the rotor and the ripple plate, the strength of the rod material and the spacing between the baffle plates.
Investigation into the Energy Demand for Palm Nut Cracking Using the Static Impact Method
Investigation into the energy demand for cracking of palm nuts using static impact method was carried out. A nut cracking energy equipment was designed and constructed for the analysis. Fresh palm kernel nuts already dried to a moisture content of 10.42%wb ready for cracking were obtained from an oil mill and characterized into five categories based on their nominal diameter as follows d<12mm; 12mm≤d<15mm; 15mm≤d<17mm; 17mm≤d<19mm; 19mm≤d20mm. The nuts were subjected to cracking using the equipment developed and visual observation was used to assess the level of cracking as follows; completely cracked (CC), completely cracked with slight damage (CCD), cracked without nut separation (CWS), unable to crack (UC) and smashed (SM). The results show that efficiency for complete cracking of nuts without defects increased with increase in drop height to a peak (80 – 100%) and then decreased. Statistical analysis show that the cracking energy determined and cracking percentage have high linear correlation at (0.91, 0.82, 0.94, 0.81 and 0.74) and corresponding high coefficient of determination (0.836, 0.671, 0.889, 0.659, 0.5407) for the various size ranges with their t test showing high significance at 5% level of probability. It was also observed that cracking energies of 0.514; 0.709; 0.904; 1.294 and 1.787 J respectively were adequate to sufficiently crack palm nuts of the five size ranges respectively and release whole kernel. The results suggests the need to grade palm kernel nuts before cracking and the design of a nut cracker with a grading component before cracking to actualize minimal breakage of kernels.