Consumption of sugarcane harvesters

Operating speed, engine rotation and crop productivity affect the fuel consumption of sugarcane harvesters.

A sugarcane harvester uses an average of 60 liters of diesel oil to harvest one hectare of sugarcane. Considering the current price of diesel oil at around R$3,00 per liter, this harvester will spend, on fuel alone, around R$180,00 per hectare harvested. Harvesting an average of 10ha per day, the daily cost of fuel will be more than R$1.800,00.

Researchers Ripoli and Ripoli (2008) stated that factors such as agronomic, environmental, technical and management conditions influence the mechanized harvesting operation and if this is not carried out within technical precepts, they can compromise the quality of the raw material, productivity and the longevity of the sugarcane field.

The higher the speed, the greater the operational capacity; with a travel speed of 7km/h the field efficiency can reach 75%. Hourly fuel consumption is also influenced by the harvester's travel speed, with the higher the speed, the higher the hourly consumption and the lower the consumption per ton of harvested cane. This work was carried out with the objective of evaluating the fuel consumption of two sugarcane harvesters as a function of travel speed and engine rotation.

Two sugarcane harvesters were evaluated in high productivity sugarcane fields (more than 100t/ha) and in lower productivity sugarcane fields (less than 40t/ha). Harvester “A” had 335 hp and tracked wheels and harvester “B” had 330 hp and tracked wheels. The harvesters were evaluated in three speed ranges (5km/h to 6km/h, 6km/h to 7km/h and 7km/h to 8km/h) and at three different engine speeds (1.900rpm, 2.000rpm and 2.100rpm).

To measure hourly and specific fuel consumption, two volumetric flowmeters with a flow rate of 10ml/pulse were used, one installed between the filters and the injection pump of the harvester engine and the other when returning the fuel to the tank. The real consumption was calculated by the difference between the values ​​of the pulses generated by the flowmeters, which sent to the data acquisition system (PLC) one pulse unit for every 10ml of fuel that passed through it. The specific consumption per ton harvested was obtained by the ratio between fuel consumption per area (L/ha) and sugarcane productivity (t/ha).

To determine the speed of movement of machines in the areas, a GPS receiver was used. The data were subjected to statistical analysis using analysis of variance and the values ​​were compared using the Tukey test at 5% significance.

Figure 1 shows the results of the Tukey test at 5% probability for the hourly consumption of harvester “A” as a function of engine rotations in different travel speed ranges. It is observed that in the speed ranges from 5km/h to 6km/h and from 6km/h to 7km/h there was no significant difference between consumption at speeds of 1.900rpm and 2.000rpm, which were significantly lower than the hourly consumption for speed recommended by the manufacturer (2.100rpm). Reducing the harvesters' engine speed from 2.100rpm to 1.900rpm resulted in savings of more than 20 liters of fuel per hour in the speed range of 6km/h to 7km/h. In the highest speed range, consumption was significantly lower at the lowest speed (39,94L/h), generating an economy of 17,04L/h in relation to the speed of 2.100rpm, however, there was no significant difference in consumption in the range speed range from 6km/h to 7km/h. Regardless of the travel speed range, there were always higher consumption values ​​at the highest speed of the harvester engine, which was not significant only in the speed range of 7km/h to 8km/h.

Figure 2 presents the results of the Tukey test at 5% probability for the hourly consumption of harvester “B” as a function of rotation in different travel speed ranges. Each speed range showed different behavior. In the range of 5km/h to 6km/h, hourly consumption was significantly lower when the machine operated with 2.000 engine rpm. In the speed range of 6km/h to 7km/h, consumption was significantly higher at 2.100rpm and did not differ in the other two ranges. In the highest speed range, hourly consumption did not differ between treatments, however, in all speed ranges consumption was numerically lower when the harvester operated with 2.000rpm in the engine.

Figure 3 shows the graph with the results of the Tukey tests at 5% probability for fuel consumption per ton of sugar cane harvested as a function of the travel speed ranges at different engine speeds. The lowest consumption per ton of sugarcane harvested by harvester “A” occurred in the speed range of 7km/h to 8km/h. Due to the low productivity of the plots harvested by harvester “A”, it did not require high engine power and the higher the travel speed, the greater the harvesting capacity of the harvesters. This explains why the lowest consumption per ton was observed in the speed range from 7km/h to 8km/h and at a speed of 1.900rpm (0,99L/t), and the highest consumption in the speed range from 5km/h to 6km/h operating with the engine at 2.100rpm (2,08L/t).

Figure 4 shows the results of the Tukey tests at 5% probability for fuel consumption per ton of sugar cane harvested by harvester “B” as a function of the travel speed ranges at different engine speeds. For all speeds analyzed, consumption was lower in the highest speed range of 7km/h to 8km/h, not being significant only for 2.000rpm.

Harvester “A” in low-productivity sugarcane fields achieved lower fuel consumption with the machine being operated at 1.900 rpm on the engine. Harvester “B” in the sugarcane field with higher productivity required greater power to carry out the harvest, with the lowest consumption observed at 2.000 rpm. Travel speed influenced fuel consumption per ton of sugarcane harvested for both areas with high and low productivity, with the higher the harvester's travel speed, the lower the fuel consumption per ton. harvested.

Gabriel Lyra, IFMT; Fabrício Campo Masiero, IFC; Kléber Pereiraanças, Carlos Renato Guedes Ramos, Camilo Giachini, FCA/Unesp Botucatu

Article published in issue 164 of Cultivar Máquinas.