Effect of the Cylindrical Cutting Blades and Travelling Speed. on the Performance of Sweet Sorghum Harvesting Equipment

Transcription

1 Effect of the Cylindrical Cutting Blades and Travelling Speed on the Performance of Sweet Sorghum Harvesting Equipment Saknarin Deeyotar 1 and Asst.Prof.Dr. Seree Wongpichet 2 1 address:saknarindeeyotar@gmail.com. Telephone number: Address:Department of Agriculture Engineering. Faculty of Engineering, Khon kaen University, Khon kaen 40002, Thailand 2 address:serwon@kku.ac.th. Telephone number: Address.Department of Agriculture Engineering. Faculty of Engineering, Khon kaen University, Khon kaen 40002, Thailand Abstract This research aims at developing harvesting equipment with cylindrical cutter for sweet sorghum harvesting. Vertical centrifugal blade mechanism is commonly used in forage harvesters. Such a mechanism would chop the plants into small pieces and transports them out of the harvesting equipment. However, this research aims to develop such mechanism for harvesting equipment without the chopping process. The laboratory tests were done under simulation harvesting condition in the laboratory, The appropriate blade cutting speed was found. The efficiencies of the harvesting equipment with the varied blade speed and travelling speed were collected. The findings of the study were used to design and construct the harvester prototypes that would harvest one row at a time. The field test was conducted to evaluate the functions of the prototype in farmer fields. The results showed that the increasing of the blade speed between m/s did not effect the efficiency of the equipment, nor the cutting loss, but affects the height of the stump, which decreased by 4.82 mm/stump. By increasing the travelling speed from 2.00 to 3.50 km/hr, the efficiency of the equipment was increased by 4.14 %, the cutting loss was decreased by 6.86 %, but the loss from the remaining stumps was increased by 2.10 %. The fuel consumption cost of this prototype is lower than the cost of labour wage by baht/ha. Keywords: Cylindrical cutter, Sweet sorghum harvester

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3 1. Introduction Thailand is heavily reliant on its energy imports. In 2010, the net value of import increased by 19.8% to 911 billion baht (Ministry of Energy, 2011). The government has been focusing on policies in the area of alternative energy, especially the ethanol and gasoline mixture. The current government is promoting the use of gasohol instead of benzene and has permitted the construction of 54 ethanol plants in the country. The project will require huge amount of resources while the current raw materials in use are only molasses and cassava, which is clearly insufficient to meet the demand of the ethanol plants. Moreover, because of its similar seasonal harvesting period, November April (Seree Wongpichet, 2008), the feeding of these raw materials such as the cane (molasses) and cassava will not be constant for all ethanol plants. Sweet sorghum is another viable option as a supplemental raw material to enhance ethanol production. Since the sweetness of the juice in its trunk is at a similar level of that in sugarcane, the sweet sorghum juice squeezed from the plant can directly produce ethanol with similar amount of ethanol obtained from sugarcane at 70 litre / tonne (Prasit Jaisil, 2005). Furthermore, the period of sweet sorghum reaping is only days with the growing season between May October that will fill the output gap between the harvesting season sugarcane and cassava (Seree Wongpichet, 2008). Sweet sorghum s harvesting process is similar to that of sugarcane. The research found that the reaping process of sweet sorghum, which includes harvesting, trimming and transporting to trucks, requires 49.2 workers/hr/ha. The whole process requires 300 workers/hr/ha. (Seree Wongpichet, 2008) With the labour cost just for harvesting process as high as 1,843.6 baht/ha and the whole expenditure of 11,250 baht/ha labor (at

4 the wage of 300 baht/worker/day, the idea was to reduce the cost of sweet sorghum harvest by developing harvesters that will serve as a substitute for labour. Refer to the former researches (Luigi Prai, 2008 and Glen C. Rain, 1993), the sweet sorghum harvesting machines were developed in 3 directions. First, single chop and double shop silage harvesters were applied to sweet sorghum harvesting without any machine modification. The sweet sorghum harvested by these machines was chopped into small pieces which are fermented easily. Consequently, the fermentation of chopped sweet sorghum affected in 50% of sugar loss in 24 hours after harvested. However, there was an effort to equip the milling system with the harvester to mill the chopped sweet sorghum, but the fermentation still affected in 40% loss of sugar loss. Thus, this direction of development become less utilization Second direction was the application of the sugarcane harvester without any modification as a sweet sorghum harvester. Luigi Prai, 2008 reported the test result of the sugarcane harvester model Claas cc1400 application. The tested machine cut 3 rows of the sweet sorghum at the same time. Then they was chopped into 320 mm length and conveyed to the truck after leave separation by air. The field capacity was 0.77 ha/h with the traveling speed during harvesting operation at 4.3 km/h. As the sweet sorghum was chopped in large stalks, the loss of sweetness was low at 10% at 7 days after harvested. This direction was popular among farmer in southern part of the united state of America who owns the large area. Nevertheless, there was many limitation of this harvester application found in the middle part of the united state including Europe which the field size is small. Glen C. Rain, 1993 suggested that the field size should be larger than 10 ha for this kind of application.

5 Third, there were many efforts to develop the sweet sorghum harvesting machine for small size field. This direction can be divided into 2 categories. First category was the development of the sweet sorghum cutting machine. Luigi Prai, 2008 reported the operation test result of sweet sorghum cutting machine of Pasquli. The 2 rows of sweet sorghum were cut, then their leaves were split and the sweet sorghum stalks were laid down in the field. The field capacity is 0.11 ha/h with the average speed of 0.9 km/h. Moreover, Omin Ghahraei et al, 2008 reported another test result of the sweet sorghum cutting machine. This machine cut one row of the sweet sorghum and lay down the stalk in the field without leaves separation. The field capacity was also 0.11 ha/h with the average speed of 2 km/h. Second category was the development of the small size combined harvester for sweet sorghum which had the similar operation to the sugarcane harvester. The operating process consisted of leaves splitting, base cutting, 300 mm chopping, leaves separating by air and conveying to the truck. Refer to the test result (Luigi Prai, 2008), the harvester cut one row of sweet sorghum, and had the field capacity of 0.05 ha/h with the average speed of 0.8 km/h. Even if the sweet sorghum has the capability to be used in Ethanol production, the research and development of the sweet sorghum harvesting machine is not available in Thailand at present. Accordingly, the development of the sweet sorghum harvesting machine should be considered in order to solve the labor shortage in the field of agriculture. This research considered the development in the second category of the third direction and focused on the base cutting part and conveying part to the next parts (such as chopping, leaves separating and conveying to the truck)

6 Similar to the sugarcane harvester and silage harvester, part of the sweet sorghum harvesting machine developed in the former research mentioned in the second category of third direction used the counter rotating cutter (Fig. 1-A) to cut the base of stalk and convey the stalk into the vertical feed rolls to be conveyed to the next part of machine. Even if the mechanism mentioned above had good performance, but had the complex assembly and need well maintenance. Thus, this research chose the cylindrical cutter (Fig. 1-B) with the simple mechanism and easy to maintenance. This mechanism was widely used in the single chop silage harvester which Thai farmers are familiar with. Generally, the cylindrical cutter will cut the base of stalk, pick the stalk upward, chop the stalk and hurl the chopped sweet sorghum of the machine. This research aims to develop the cylindrical cutter as a base cutter without chopping and able to hurl the stalk of the machine to convey the cut stalk to the next process.

7 2. Materials and Methods The research procedure includes construction of testing unit and simulating an artificial harvesting test in a laboratory to find a suitable blade velocity. The results test will then be used to design and construct a prototype of a harvesting equipment to evaluate the performance in the field. 2.1 Laboratory test: The effect of the cylindrical cutting blades and travelling speed on the performance of sweet sorghum harvesting equipment 2.1.1) A testing unit for a simulation of harvesting work in a laboratory The sweet sorghum harvesting equipment used cylindrical cutter (Figure 1-B) to cut each row of sweet sorghum. When the harvesting equipment approaches the row of sweet sorghum, the sweet sorghum will be supported with the mechanism attached at the front of the blade. At the same time, the cylindrical cutter will rotate to cut at the base of the trunk (Figure 2-A). After that, sweet sorghum with average height of 2.5 m. will be pulled and swung over the blade towards the back of the harvesting equipment (Figure 2-B). As the equipment for the next process was not yet developed, in this research, the cut stalk was hurl off the machine to be laid down behind the developed harvesting equipment ) Test method and testing indicators The study is aimed to find an appropriate blade speed and traveling speed for the harvesting process of sweet sorghum to easily transported across the blade to the back of the harvesting equipment. Refer to the preminary test, the laboratory variation of cutting speed was limited between m/s. The traveling speed was limited to the traveling speed of tractors at the 1st, 2nd and 3rd gear position, respectively. Therefore, considering 4 levels of cutting speed (6.28, 8.64, and m/s) and 3

8 levels of traveling speed (2.0, 2.75 and 3.5 km/hr), the 3x4 factorial in Completely Randomized Design (CRD) with 3 replications were arranged as shown in the following diagram. Travelling speed Blade velocity Replications 2 km/hr 6.28 m/s 8.64 m/s m/s m/s 2.75 km/hr 6.28 m/s 8.64 m/s m/s m/s 3.50 km/hr 6.28 m/s 8.64 m/s m/s m/s

9 The indicating/dependent factors are harvesting efficiency (% wt), harvesting loss (% wt), height of remaining stumps (mm/stump) and the cutting loss (% wt) and cutting torque (N-m). 2.2 Field experiment: Performance evaluation of the prototype of the sweet sorghum harvesting equipment. The results from the laboratory test were used to design and construct a prototype of a sweet sorghum harvesting equipment for a one-row harvest with a 33.6 kw tractor. The prototype was tested in the field with a limitation of the gear set to rotate the blade. The blade velocity set in the study was set at m/s at the 4 levels of travelling speed. The field test was done with 2 replications. Each replication was done in a 5.4 x 19 sq.m. field. The indicating/dependent factors are field capacity (ha/hr), field efficiency (%), harvesting efficiency (% wt), harvesting loss (% wt), height of remaining stumps (mm/stump) and the cutting loss (% wt) and cutting torque (N-m) and fuel consumption (l/ha) calculated by the following formula. Field capacity (ha/hr) = The areas of harvest, hectare. Total time of harvest, hr Field efficiency (%) = Time of harvest, hr Total time of harvest, hr Harvesting efficiency (% wt) = W a x 100 W a + W b + W c Harvesting loss (% wt) = W x + W y + W z x 100 W a + W b + W c

10 The cutting loss (% wt) = Where : W b x 100 W a + W b + W c W a = Weight of stem can be harvested (Figure 3 ). W b = Weight of stump after cutting (Figure 3) W c = Weight of stem cannot be harvested W c = W x + W y + W z W x = Weight of stem was cut off and cannot transported across the blade to the back of the harvesting equipment (Figure 3). W y = Weight of stem was cut but not broken W z = Weight of the trunk is not cut off due to not in wide harvest (Figure 1-B. Harvesting width of 200 mm). Fuel consumption (l/ha) = The amount of fuel used during the operation, liter The areas of harvest, hectare. Cutting torque (T),( N-m) = Measurement the shaft of the blade (Figure 3). Height of remaining stumps (mm/stump) = Measurement the height stump from ground surface to the top of stump (Figure 3).

11 3. Results and Discussion 3.1 The laboratory test result: The effect of the cylindrical cutting blades and travelling speed on the performance of sweet sorghum harvesting equipment. The Sweet Sorghum used in the study was KKU.40, 100 days old, planted using a Jab Planter tool. The average distance between each row and plot was 504 and 141 mm respectively. Each plot had 1-2 trunks with average height of 2,484 mm, average stump diameter of 13 mm (measured at 100 mm from soil surface, Figure 3), and moisture content of 47.4% wb. The laboratory test results were shown in Table 1 and Figure 4 to ) The effect of the blade and travelling speed on harvsting efficiency and harvesting loss It was found that the change of blade speed between m/s did not affect on the harvesting efficiency and loss. The travelling speed between raised from 2.00 to 3.50 km/hr, on the other hand, increased the harvesting efficiency with a statistic significance (P-value = 0.035). The cut sweet sorghum was increased by 4.14% by weight. Moreover, the harvesting loss was also reduced 6.86% with a statistic significance (P-value = 0.027). The findings can be illustrated with a linear correlation shown in respectively (Figure 4 and 5). From the study, it was found that when using travelling speed at 3.50 km/hr, the hervesting tool was able to cultivate 85% of the sweet sorghum with only 5.29% harvesting loss ) The effect of the blade and the travelling speed on the height of the remaining stumps and its cutting loss During the study, the harvester s blade was set to be 5 mm above the soil surface. It was found that the blade speed raised from 6.28 to13.35 m/s reduced the height of the

12 remaining stumps with a statistic significance (P-value = 0.000). On average, the hieght decreased by 4.82 mm. The raising travelling speed from 2.00 to 3.50 km/hr increased the height of the remaining stumps with a statistic significance (P-value = 0.001). Nonetheless, the raising travelling speed between km/hr did not lead to any change in the height of the remaining stumps. All of these finindings can be illustrated in a linear correlation shown in Figure 6. At the blade speed of m/s, if the travelling speed was at km/hr, the height of the remaining stumps would be on average 7 mm, but if the travelling speed was at 3.50 km/hr, the height of remaining stumps wold be on average at 10 mm. This could be concluded that at different travelling speed, cutting with high speed blade will result in lower height of the remaining stumps, closer to the value adjusted before the study at 5 mm. The remaining stumps were weighed to calculate the cutting loss. Figure 7 shows the correlation between the blade speed and the cutting loss. It was found that when the travelling speed was at km/hr, increasing of blade speed reduced the cutting loss on average by 4.40%. When the blade speed was at m/s, travelling speed at and 3.50 km/hr would result in lower cutting loss on average by 4.95% and 7.04% respectively ) The effect of blade and travelling speed on the sweet sorghum cutting torque The ananlysis of the results showed that a the blade speed increased from 6.28 to m/s led to a reduction in sweet sorghum cutting torque with a statistic significance (P-value=0.000). The raising travelling speed from 2.00 to 3.50 km/hr led to an increase in cutting torque with a statistic significance (P-value=0.000). The findings can be shown as a linear correlation illustrated in Figure 8. When the balde speed was at 13.35

13 m/s and the travelling speed was at 2.00 km/hr, the cutting torque was at N-m. when the travelling speed was at 3.50 km/hr, cutting torque increased to N-m. 3.2 The field experiment result: Performance evaluation of the prototype of the sweet sorghum harvesting equipment. From the findings in the laboratory tests, a prototype of the sweet sorghum harvesting equipment was developed to evaluate its performance in the actual farming condition (Figure 9 and 10). For one-row harvest, the speed of the blade was adjusted to m/s, higher than speed in the laboratory tests. The adjustment was made due to limitation of gear used in the prototype model. However, the increased speed could give a better result in terms of height of the chopped stump which is lower. In addition to that, the blade was adjusted to be 80 mm above the soil surface to reduce the problem with chopping into the soil surface. The prototype was tested under the real harvesting condition with 33.6 kw tractor as a power source. The results are shown in the Table 2 to 4. It was found that when the travelling speed exceeded 3.09 km/hr, the performance of the prototype visibly reduced (Table 3). Because of the speed increased, more sweet sorghum was harvested with total volume of trunks and leaves larger than the input canal which was designed for only 0.02 sq.m.. Hence, this caused congestion within the prototype, obstructed the conveyer belt and hamppered the harvesting process. It was concluded that the prototype could not work under the condition in which the travelling speed exceeds about 3.1 km/hr. When comparing the results of the travelling speed from 1.91 to 3.09 km/hr (Table 3 and 4) it was found that an increase in the travelling speed resulted in higher field capacity but barely changed the field efficiency, the harvesting efficiency, the harvesting

14 loss and the cutting loss from remaining stumps. It can be concluded that the prototype had the field capacity at 0.15 ha/hr or 1,895 kg/hr and the average field efficiency was at 74.04%. An average harvesting efficiency was 88.00% while the average harvesting loss was 4.82%. An average cutting loss from the remaining stumps was 7.19% and the prototype needed average torque of N-m. Fuel consumption was at 52.1 l/hr or 1,562 baht/ha at the fuel price of 30 baht/l. The cost of using the sweet sorghum harvester is lower than that of using human labour by 1,843 baht/ha. It can be concluded that the sweet sorghum harvesting with cylindrical cutter equipment has potential to be researched to further development. 4. Conclusions The laboratory results shows that; by increasing blades speeds from 6.28 to m/s the harvesting efficiency barely affected but has reduced the height of the remaining stumps was reduced by 4.82 mm each. By increasing the travelling speed from 2.00 to 3.50 km/hr; the harvesting efficiency was raised by 4.14%, the harvesting loss was reduced by 6.86 % but the loss from the remaining stumps was increased by 2.10%. The prototype for a one-row harvest will then be constructed from the laboratory findings to evaluate the performance under actual farming condition. The results show that, the cost from fuel consumption was lower than that of human labour by baht/ha. It may be concluded that the method of sweet sorghum harvesting with cylindrical cutter has great potential to be researched for further development. Acknowledgement This research was funded by the National Research Universities Project. Special thanks are due to Faculty of Engineering and Faculty of Agriculture of Khon Kaen

15 University for their permission to use their laboratories and sweet sorghum for carrying out this project. References Ghahraei O.,M.H. Khoshtaghaza and D. Bin Ahmad Design and Development Special Cutting System For Sweet Sorgum Harveater. Janal Center Europane Fo Agricoltura. 3 : Ministry of Energy Annual Report Ministry of Energy. Prasit Jaisil Potential of using sweet sorghum as an additional raw material for commercial ethanol production. Proceedings of the 32nd Thai National Corn and Sorghum Research Conference, Bangkok (Thailand), p Pari L State of the are: Harvesting, Storage and Logistic of the Sweet Sorghum. Proceedings of the 16th European Biomass conference & Exhibition, 2-6 June 2008.: Rains G. C.,J.S. Cundiff, and G. E. Welbaum Sweet Sorghum for a Piedmont Ethanol Industryp. Proceedings of the 2nd National Symposium Available source 15/09/2012 Seree Wongpichet Research report: Development of the Sweet Sorghum Crusher for Agricultural Group. Khon Kaen University. p. 17 Suwan Homhual and Watchama Photong Single Row Forage Harvester Driven by Small Tractor. Kamphaengsaen Acad. J. Vol. 3, No. 3, 2005, : 62 69

16 Table 1 the harvesting efficiency and harvesting loss of prototype from sweet sorghum harvest in laboratory test. Traveling Speed Cutting Speed rep Wa Wa Wb Wb Wc Wc Wx Wx Total Total km/hr m/s kg % kg % kg % kg % kg % Remark: W a = Weight of stem can be harvested. W b = Weight of stump after cutting. W c = Weight of stem cannot be harvested. W x = Weight of stem was cut off and cannot transported across the blade to the back of the harvesting equipment.

17 Table 2 the harvesting efficiency and harvesting loss of prototype from sweet sorghum harvest in field test. Traveling Speed rep Wa Wa Wb Wb Wx Wx Wy Wy Wz Wz total total km/hr kg % kg % kg % kg % kg % kg % Remark: W a = Weight of stem can be harvested. W b = Weight of stump after cutting. W c = Weight of stem cannot be harvested. W x = Weight of stem was cut off and cannot transported across the blade to the back of the harvesting equipment. W y = Weight of stem was cut but not broken. W z = Weight of the trunk is not cut off due to not in wide harvest. Table 3 the performance of the sweet sorghum harvester prototype in a field 1) Travelling Speed (km/hr) Field Capacity (ha/hr) 2) Field Efficiency Cutting Torque (%) 2) (N-m) Fuel Consumption (l/ha) a a b a c a d b Remark: 1) sweet sorghum cultivated was KKU 0.40, 93 days old, grown using a row-planting tool. The average distance between each row and plot was 678 and 181 mm respectively. Each plot had 1-3 trunks with moisture content average of 48.9% wb and yield of 24,194 1 kg/ha 2) In each column, the average was derived from two repeated tests. There is no difference between average values followed by the same letter when compared the average values against the Least significant difference (LSD) at level of significance of Table 4 the performance of prototype from sweet sorghum harvest Average Harvesting loss (% wt) Travelling Average Speed Harvesting eff. 1) (km./hr) (% wt) partially cut successfully cut but not fed into the harvester remained uncut total 1) Average Cutting Loss from Remaining Stumps 1) (% wt) a a 7.23 a a a 5.28 a a a 9.06 a b b b Remark: 1) In each column, the average was derived from two repeated tests. There is no difference between average values followed by the same letter when compared the average values against the Least significant difference (LSD) at level of significance of Total

18 Counter Rotating Cutter and Vertical Feed Rolls A: Counter Rotating Cutter (S. Homhual and W.Photong, 2005) T B: Cylindrical Cutter Figure 1: Comparion of the blade between Counter Rotating Cutter (A) and Cylindrical Cutter (B).

19 (A) (B) Figure 2: Showing the process of cutting the sweet sorghum (A) and transporting process (B). Direction of motion W a W x T 100 mm Stump (w b) Figure 3: Show the sweet sorghum after harvested. The stem was cut off and cannot transported across the blade to the back of the harvesting equipment ( W x ). The stem can be harvested (W a ). The stump after cutting (W b ).

20 Harvesting Efficiency (% weight) Travelling speed (km/hr) Figure 4: Harvesting efficiency at different travelling speed. 20 Harvesting Loss (% weight) Travelling speed (km/hr) Figure 5: Harvesting loss at different travelling speed. Height of stumps (mm./stump) (3.50 km/hr), y = x R² = ( km/hr), y = x R² = Speed of Cutting Blades (m/s) V= km/hr V=3.50 km/hr Figure 6 The relation between the speed of cutting blade and the heigh of stumps.

21 20 15 (3.50 km/hr), y = x R² = km/hr 3.50 km/hr Cutting Loss (% weight) ( km/hr), y = x R² = Speed of Cutting Blades (m/s) Figure 7 The relation between the speed of cutting blade and cutting loss. Cutting torque (N-m) (2.75km/hr), y = x R² = (3.50km/hr), y = x R² = (2.00km/hr), y = x R² = km/hr 2.75 km/hr 3.50 km/hr Speed of Cutting Blades (m/s) Figure 8: The relation between the speed of cutting blade and the cutting torque.

22 Figure 9 The distance between row and plot. Direction of motion Direction of motion Figure 10 The Sweet sorghum harvesting equipment one row with a tractor while sweet sorghum harvesting.

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