Effects of Guide Vane Inclination in Axial Shelling Unit on Corn Shelling Performance

Transcription

1 Kasetsart J. (Nat. Sci.) 49 : (2015) Effects of Guide Vane Inclination in Axial Shelling Unit on Corn Shelling Performance Phatchanida Saeng-ong 1,2, Somchai Chuan-Udom 1,2,* and Khwantri Saengprachatanarak 1,2 ABSTRACT This study was conducted on the effects of guide vane inclination of an axial shelling unit on corn shelling performance, based on loss from the shelling unit, grain breakage, power requirements and specific energy consumption. It was found that when the guide vane inclination increased, loss from the shelling unit had a tendency to decrease, the power requirements and specific energy consumption tended to increase linearly and the grain breakage difference was not significant. A study of the rotor speed and feed rate showed that an increased rotor speed could decrease the loss from shelling, while the grain breakage, power requirements and specific energy consumption tended to increase. Increasing the feed rate increased the loss from the shelling unit, grain breakage and power requirements; additionally, it decreased the specific energy consumption. Keywords: Guide vane inclination, shelling unit for corn, axial shelling unit INTRODUCTION Corn is an important cereal for the economic development of Thailand as the country s total feed-corn plantation area is approximately 1.2 million ha, producing a total of approximately 5 million t, worth THB 40,000 million (approximately USD 1,250 million) according to Office of Agricultural Economics (2013). At present, corn harvesting by farmers in Thailand differs from place to place. In some areas, axial flow rice threshers have been modified into corn shellers. Attempts have been made to improve the thresher so that their performance in corn shelling is imporved (Chuan-Udom and Chinsuwan, 2009a). A study by Chuan-Udom (2012) showed that the guide vane inclination had the greatest effect on the overall loss when using a rice thresher for shelling corn. The guide vane inclination is a device used to guide materials to flow axially along the threshing shaft. Increased inclination enables materials to remain longer in the threshing unit. The study of grain loss from the use of an axial flow rice thresher indicated that when the guide vane inclination from the threshing shaft was increased, losses tended to decrease. A study by Chuan-Udom and Chinsuwan (2011) demonstrated that the amount of grain breakage in Hom Mali rice was not significantly different when the vane inclinations changed. A previous study by Chuan-Udom and Chinsuwan 1 Department of Agricultural Engineering, Faculty of Engineering, Khon Kaen University, Khon Kaen 40002, Thailand. 2 Applied Engineering for Important Crops of the North East Research Group, Khon Kaen University, Khon Kaen 40002, Thailand. * Corresponding author, somchai.chuan@gmail.com Received date : 15/01/15 Accepted date : 06/07/15

2 762 Kasetsart J. (Nat. Sci.) 49(5) (2009b) and subsequent study by Doungpueng and Chuan-Udom (2014) showed that increasing the vane inclination in the shaft axis resulted in diminished loss from rice threshing. Another study on the adjustment of vane inclination in threshing Chainat 1 rice by Chuan-Udom (2011) showed that greater vane inclination during the sorting stage of the threshing unit tended to substantially increase the power requirements for threshing. Gummert et al. (1992) studied an axial flow rice thresher and found that vane inclination affected the flow of materials in the threshing unit. By increasing the inclination, the materials remained in the shelling unit longer and grains were separated from the shell better, thereby decreasing the loss. Two factors aside from vane inclination have an impact on the loss in the threshing step, namely rotor speed and feed rate. Chuan-Udom and Chinsuwan (2009b) performed a study on an axial flow rice thresher and found that the rotor speed and feed rate affected the loss in the threshing unit. The faster rotor speed diminished the loss. When the feed rate was increased, the loss increased. This was similar to the results of Harrison (1991) who studied the axial flow in a barley combine unit and found that the increased feed rate resulted in an increase in the total loss and power requirements. Changrue (1999) also showed that a higher rotor speed increased the power needs and a higher feed rate required more power to shell corn because more materials were fed into the threshing unit, resulting in a greater resistant force. It is apparent that past studies have shown that the guide vane inclination affects the performance of an axial flow thresher unit and shelling unit to a relatively high degree. Thus, this research studied the effects of the guide vane inclination on the performance of a corn shelling unit to determine the most appropriate vane inclination, as well as undertaking further study on the effects of the rotor speed and feed rate on the performance of a corn shelling unit. MATERIALS AND METHODS Equipment used in the test Testing was performed using an axial corn shelling unit (Figure 1) of the throw-in type with a width of 1.83 m, a length of 1.90 m and a height of 1.60 m. A 5.59 kw electric motor was used as the power source. The rotor speed of the sheller and the feed rate were adjustable. In the test, Pioneer B80 whole corns were shelled. During the test, a torque sensor, SG-Link-OEM-LXRS Wireless Analog Sensor Node (Lord MicroStrain; Williston, VT, USA) was used to change the parameters to meet the power requirements and specific energy consumption (SEC). The test was performed entirely within a laboratory. Study of guide vane inclination In order to determine the appropriate guide vane inclination, five levels of vane inclination were chosen for testing 72, 76, 80, 84 and 88 degrees from the thresher axis. A constant rotor speed of 9.6 m.s -1 was used and the feed rate was constant at 1.5 t.hr -1. The moisture content of the grains, corncobs and corn husks was 12.35, and % (wet basis), respectively. A randomized complete block design (RCBD) with three replicates or blocks was used. The guide vane inclination (θ) as shown in Figure 1 was calculated based on trigonometric principles using Equation 1: θ = tan -1 (Y/X) (1) Study of rotor speed and feed rate In the study, the vane inclination that gave the best performance was chosen for testing and the rotor speeds were set at four levels 8, 9.5, 11, and 12.5 m.s -1. The four feed rates set were 0.5, 1, 1.5 and 2 t.hr -1 with the moisture content of the grains, corncobs and corn husks at 18.96, 31.68, and 13.17% (wet basis), respectively. For this test, a factorial RCBD (4 4) with three replicates or blocks was used.

3 Kasetsart J. (Nat. Sci.) 49(5) 763 Figure 1 (a) Equipment used in the test and (b) Measuring guide vane inclination. Testing method Testing of each factor involved three replications, each using 10 kg of ear corn. Data were collected from the materials weighed at the discharge of corncobs and at the corn husks outlet. The loss from the shelling unit consists of separating losses and shelling losses. Grains and materials other than grain were sampled at a cleaning sieve to determine the weight of the grain. Then, a random weight of shelled grain (whole and damaged grain) per unit time collected at the main grain outlet was used to measure breakage. The power requirement for shelling was measured using the torque sensor (SG-Link Model; Lord MicroStrain; Williston, VT, USA). Torque was measured continuously while corns were shelled. The parameters obtained were used to calculate the power requirements and specific energy consumption. Indicator parameters The indicating parameters in the test comprised loss from the shelling unit and grain breakage calculations were based on Regional Network for Agricultural Machinery (RNAM) test codes and procedures for farm machinery (ESCAP RNAM, 1995). The power requirement and specific energy consumption can be calculated using the following equations. Loss from the shelling unit (total losses) calculated using Equation 2: TL = [B / (A+B)] 100 (2) where, TL is the loss from the shelling unit in percent, A is the weight of shelled grain (whole and damage grain) per unit time collected at the main grain outlet in grams and B is the weight of the shelled and unshelled grain per unit time collected at the corncobs and corn husks outlet per unit time in grams. Grain breakage (the ratio of grain broken weight after shelling to weight of grain sampled from the tray beneath the shelling mesh) was determined using Equation 3: GB = (E / C) 100 (3) where, GB is the grain breakage in percent, C is the random weight of shelled grain (whole and damaged grain) per unit time collected at the main grain outlet in grams and E is the weight of grain breakage collected at the main grain outlet in grams. Power requirement was calculated from the force obtained from the torque sensor using Equation 4: P = τω (4)

4 764 Kasetsart J. (Nat. Sci.) 49(5) where, P is the power requirement in watts, τ is the torque of the shaft sheller in N.m and ω is the angular velocity of the rotor speed in rad.s -1. Specific energy consumption (energy per unit mass) was determined using Equation 5: SEC = P / FR (5) where, SEC is the specific energy consumption in kwh.t -1, P is the power requirement in watts and FR is the feed rate of the feeder in t.hr -1. RESULTS AND DISCUSSION Effect of guide vane inclination on performance of corn shelling The losses from the shelling unit (TL) were from 1.53 ± 0.10 to ± 1.88%. The amount of grain breakage (GB) was from 0.31 ± 0.07 to 0.43 ± 0.10%. The power requirement (P) was from ± to ± W and the specific energy consumption was from ± to ± 7.10 W.hr.t -1, as shown in Table 1. Table 2 show the analysis of variance which indicated that adjustment of the guide vane inclination significantly affected the loss from the shelling unit, the power requirement and specific energy consumption at the P < 0.01 level. However, grain breakage was not significantly different because as the guide vane inclination increased, shelling was not violent and as a result, grain breakage did not change (Chuan-Udom and Chinsuwan, 2011). From Table 1, a relationship graph was built between the guide vane inclination and the loss from the shelling unit, as shown in Figure 2. It was found that when the inclination increased, loss from the shelling unit decreased curvilinearly. Increased guide vane inclination meant a longer time for corns to remain in the shelling unit, resulting in better shelling and sorting (Gummert et al., 1992). The correlation of vane inclination affecting loss from the shelling unit can be represented by Equation 6, where the coefficient of determination (R 2 ) = 0.98 Table 1 Effect of guide vane inclination adjustment on loss from the shelling unit, grain breakage and power requirement for corn shelling. GI ( ) TL (%) GB (%) P (W) SEC (Wh.t -1 ) ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 7.10 GI = Guide vane inclination, TL = Loss for shelling unit, GB = Brain breakage, P = Power requirement, SEC = Specific energy consumption. Values shown as mean ± SE. Table 2 Analysis of statistical variance of loss from the shelling unit, grain breakage and power requirement affected from on guide vane inclination. Source of Variation df MS F Loss from the shelling unit (%) ** Grain breakage (%) ns Power requirement (Watts) ** Specific energy consumption (Wh.t -1 ) ** ns = Not significant, * = Significant at P < 0.05, ** = Highly significant at P < 0.01

5 Kasetsart J. (Nat. Sci.) 49(5) 765 TL = e -0.16GI (6) A relationship graph was built between the guide vane inclination and the power requirement, as shown in Figure 3. It was found that when the guide vane inclination increased, the power requirement increased. With increased guide vane inclination, corn remained longer in the threshing unit, resulting in increased shelling of corn. However, corn was flowing continuously into the machine; thus, the amount of corn in the shelling unit increased and the power requirement increased (Harrison, 1991). The correlation between the guide vane inclination and the power requirement can be represented by Equation 7, with R² = P = 22.85GI (7) The relationship graph between the guide vane inclination and the specific energy Figure 2 Effect of guide vane inclination from the thresher shaft axis on loss from the shelling unit. consumption is shown in Figure 4. It was found that when the guide vane inclination increased, the specific energy consumption increased linearly, identically to the power requirement. When the power requirement increased it affected the specific energy consumption. The correlation between the guide vane inclination and specific energy consumption can be represented by Equation 8, with R² = SEC = 15.23GI (8) Effect of rotor speed and feed rate on performance of corn shelling. The axial flow corn-shelling unit was adjusted so that the rotor speed (RS) was m.s -1 and the feed rate (FR) of ear corn was in the range t.hr -1 and using a guide vane inclination of 87. The Thai Industrial Standards Institute (1988) has determined the total losses from a sheller should not exceed 4%. This resulted in loss from the shelling unit (TL) of 1.21 ± 0.12% to 4.92 ± 0.35%, grain breakage (GB) between 0.84 ± 0.11% and 1.64 ± 0.14% with a power requirement (P) of 0.78 ± 0.01 to 2.41 ± 0.04 kw and specific energy consumption (SEC) of 0.92 ± 0.01 to 2.87 ± 0.06 kwh.t -1, as shown in Table 3. The statistical variance analyzed from the data in Table 3 revealed that altering the rotor speed significantly affected the loss from the shelling unit, grain breakage, the power requirement and specific energy consumption Figure 3 Effect of guide vane inclination from the threshing shaft axis on power requirements. Figure 4 Effect of guide vane inclination from the threshing shaft axis on specific energy consumption.

6 766 Kasetsart J. (Nat. Sci.) 49(5) (P < 0.01). Feed rates also significantly influenced the loss from the shelling unit and grain breakage (P < 0.05), as well as affecting the power requirement and specific energy consumption (P < 0.01). Loss from the shelling unit and grain breakage were not correlated with rotor speed and feed rate. The power requirement and specific energy consumption correlated with the linear speed and feed rate (P < 0.01), as shown in Table 4. Effects of rotor speed and feed rate on loss from the shelling unit. Data from Table 3 were used to create a regression equation between the rotor speed and the feed rate, which affected the loss from the shelling unit; no no correlation was found, as shown in Table 5. It was shown that a Model 1 Equation should be used because it yielded the highest adjusted R 2, with the standard error being the lowest. Table 3 Effects of rotor speed and feed rate adjustment on loss from the shelling unit, grain breakage, power requirement and specific energy consumption in corn shelling. RS (m.s -1 ) FR (t.hr -1 ) TL (%) GB (%) P (kw) SEC (kwh.t -1 ) ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.02 RS = Rotor speed, FR = Feed rate, TL = Loss for shelling unit, GB = Brain breakage, P = Power requirement, SEC = Specific energy consumption. Values shown as mean±se. Table 4 Analysis of variance of loss from the shelling unit, grain breakage, power requirement and specific energy consumption affected from rotor speed and feed rate. Source of Variation TL GB P SEC Rotor Speed (RS) ** ** ** ** Feed Rate (FR) 3.034* 4.005* ** ** Block 1.251ns 2.026ns 0.748ns 0.117ns RS * FR 0.803ns 0.985ns 8.352** ** TL = Loss for shelling unit, GB = Brain breakage, P = Power requirement, SEC = Specific energy consumption ns = Not significant, * = Significant at P < 0.05, ** = Highly significant at P < 0.01

7 Kasetsart J. (Nat. Sci.) 49(5) 767 Model 1 in Table 5, indicating the relationship between the rotor speed and the feed rate affecting the loss from the shelling unit is shown in Figure 5. From the graph, the loss from the shelling unit tended to decrease curvilinearly when the rotor speed increased. When the feed rate increased, the total loss increased slightly because the increased rotor speed brought about increased centrifugal force in the sheller at the end of the peg teeth, resulting in much better shelling. An increased feed rate into the shelling unit resulted in a decrease in the rotor speed. Thus, separation and shelling decreased, leading to a greater loss from the shelling unit (Chuan-Udom and Chinsuwan, 2009b). Effects of rotor speed and feed rate on grain breakage. From Table 3, a regression equation was created between the rotor speed and feed rate on grain breakage, with no interrelation apparent between the rotor speed and feed rate, as shown in Table 6. A Model 1 Equation was found to be most suitable because it yielded the highest adjusted R 2 and the lowest standard error. Figure 6 show the relationship between the rotor speed and the feed rate that affected the grain breakage from Model 1 in Table 6. An increase in the rotor speed tended to increase the grain breakage because the increased rotor speed resulted in greater centrifugal force during shelling. Violent beating caused more broken grains. When feed rates of t.hr -1 were tested, it was discovered that the grain breakage was greatest at 1.5 t.hr -1. Breakage tended to decrease when the feed rate was higher than 1.5 t.hr -1 because this rate meant more material remained in the shelling unit and there was less chance of grain being beaten by the peg teeth. The rotor speed and a higher feed rate during operation could lower the revolution speed (Chuan-Udom and Chinsuwan, 2011). Table 5 Equation from regression analysis of rotor speed (RS) and feed rate (FR) on loss from the shelling unit (TL). Model Equation Adj. R 2 SE P-value TL = (RS) (RS) (FR) 0.425(FR) 2 2 TL = (RS) (RS) (FR) 3 TL = (RS) (FR) (FR) 4 TL = (RS) (FR) Adj. R 2 = Adjusted coefficient of determination. TL (%) Feed rate (t.hr -1 ) Rotor speed (m.s -1 ) Figure 5 Effects of rotor and feed rate on loss from the shelling unit (TL).

8 768 Kasetsart J. (Nat. Sci.) 49(5) Effects of rotor speed and feed rate on power requirement. The data shown in Table 3 were used to develop a regression equation between the rotor speed and feed rate that was used to predict the power requirement as shown in Table 7. Models 1 4 were tested and Model 3 was found to be the most appropriate because it had the greatest adjusted R 2 and the standard error was the lowest. The graph demonstrating the relationship between the rotor speed and the feed rate with the power requirement (Figure 7) was built using the Model 3 Equation from Table 7. It can be seen that when the rotor speed increased, the graph showed a linear increase and the feed rate showed a polynomial degree 2 increase. when the rotor speed increased, the power required for rotating also increased. Due to the increased feed rate, more materials were fed into the shelling unit and the power requirement increased (Gummert et al., 1992). Effects of rotor speed and feed rate on specific energy consumption. The data shown in Table 3 was used to develop a regression equation between the rotor speed and the feed rate to predict the specific energy consumption as shown in Table 8. Models 1 to 4 were considered and as shown in Table 8, Model 1 was found to be the most suitable because it provided the highest adjusted R 2. The graph showing the relationship between the rotor speed and the feed rate with specific energy consumption (Figure 8) was created using the Model 1 Equation from Table 8. As the rotor speed increased, the SEC also increased. With an increase in the feed rate, the SEC tended to decrease. This correlated with a Table 6 Equations from regression analysis of rotor speed (RS) and feed rate (FR) on grain breakage (GB). Model Equation Adj.R 2 SE P-value GB = (RS) (RS) (FR) (FR) 2 2 GB = (RS) (RS) (FR) 3 GB = (RS) (FR) (FR) 4 GB = (RS) (FR) Adj. R 2 = Adjusted coefficient of determination. GB (%) Feed rate (t.hr -1 ) Rotor speed (m.s -1 ) Figure 6 Effects of rotor speed and feed rate on grain breakage (GB).

9 Kasetsart J. (Nat. Sci.) 49(5) 769 study by Sudajan et al. (2002), where the power requirement per shelling was determined during equal periods and with an increased feed rate, the specific energy consumption tended to decrease. CONCLUSION breakage, power requirement and specific energy consumption tended to increase. 3. An increased feed rate also increased the loss from the shelling unit, the grain breakage and the power requirement. However, the specific energy consumption tended to decrease. 1. Increased guide vane inclination resulted in a decrease in the loss from the shelling unit with an increase in the power requirement and specific energy consumption. No effect was found on grain breakage. 2. The increase in the rotor speed tended to reduce the shelling unit loss, while the grain ACKNOWLEDGEMENTS The authors are grateful to the Agricultural Research Development Agency (Public Organization) and Khon Kaen University, Thailand. Table 7 Equation from regression analysis of rotor speed (RS) and feed rate (FR) on power requirement (P). Model Equation Adj.R 2 SE P-value 1 P = (RS) (RS) (FR) (FR) (FR)(RS) 2 P = (RS) (RS) (FR) (FR)(RS) 3 P = (RS) (FR) (FR) (FR)(RS) 4 P = (RS) (FR) (FR)(RS) Adj. R 2 = Adjusted coefficient of determination. P (%) Feed rate (t.hr -1 ) Rotor speed (m.s -1 ) Figure 7 Effects of rotor speed and feed rate on power requirement (P).

10 770 Kasetsart J. (Nat. Sci.) 49(5) Table 8 Equation for regression analysis of the effect of rotor speed (RS) and feed rate (FR) on specific energy consumption (SEC). Model Equation Adj.R 2 SE P-value 1 SEC = (RS) (RS) (FR) (FR) (FR)(RS) 2 SEC = (RS) (RS) (FR) (FR)(RS) 3 SEC = (RS) (FR) (FR) (FR)(RS) 4 SEC = (RS) (FR) (FR)(RS) Adj. R 2 = Adjusted coefficient of determination. SEC (%) Feed rate (t.hr -1 ) Rotor speed (m.s -1 ) Figure 8 Effects of rotor speed and feed rate on specific energy consumption (SEC). LITERATURE CITED Changrue, V Development of Corn Husker Sheller. M. Eng. Thesis, Kasetsart University. Bangkok, Thailand. 83 pp. [in Thai] Chuan-Udom, S Patters of adjustment of guide vane inclination of axial flow rice threshing unit affecting on threshing unit losses and power requirement when threshing Chainat 1 variety. KKU. Res. J. 16: [in Thai] Chuan-Udom, S Operating factors of Thai threshers affecting corn shelling losses. Songklanakarin J. Sci. Technol. 35: Chuan-Udom, S. and W. Chinsuwan. 2009a. Assessment of performance of axial flow rice threshers for corn shelling. KKU. Res. J. 14: [in Thai]. 2009b. Threshing unit losses prediction for Thai axial flow rice combine harvester. Agric. Mech. in Asia, Africa and Latin America 40: Effects of operating factors of an axial flow rice combine harvester on grain breakage. Songklanakarin J. Sci. Technol. 33: Doungpueng, K., and S. Chuan-Udom Effects of guide vane inclination patterns on threshing losses and power requirement. Kasetsart J. (Nat. Sci.) 48: ESCAP RNAM RNAM Test Codes and Procedures for Farm Machinery, Technical Series No nd ed. Bangkok, Thailand. 468 pp.

11 Kasetsart J. (Nat. Sci.) 49(5) 771 Gummert, M., H.D. Kutzbach, W. Muhlbauer, P. Wackerand G.R. Quick Performance evaluation of an IRRI axial-flow paddy thresher. Agric. Mech. in Asia, Africa and Latin America 34: Harrison, H.P Rotor power and losses of an axial-flow combine. Am. Soc. Agric. Eng 34: Office of Agricultural Economics Agricultural Statistics. [Available from: [Sourced: 7 March 2013]. Sudajan, S., V.M. Salokheand K. Triratanasirichai Effect of type of drum, drum speed and feed rate on sunflower threshing. Biosys. Eng. J. 83: Thai Industrial Standards Institute TISI Standards for power maize shellers. Ministry of Industry. Bangkok, Thailand. 11 pp. [in Thai]