Determining the operating parameters of a pruning residues shredder under different working conditions

Türkiye is a country that can cultivate various agricultural products due to its geographical location and climatic features. In recent years, there has been an increase in both the quantity and quality of fruit production areas. Consequently, significant amounts of agricultural residues are generated. It is important to propose appropriate solutions considering the material properties, regional factors, and economic conditions for the utilization of agricultural residues to prevent environmental damage and contribute to the economy. One of the issues that has emerged is how pruning residues can be effectively utilized. It is necessary to evaluate pruning residues in a way that does not harm the environment and brings economic benefits. One critical step in the evaluation process is the shredding (size reduction) of residues. Depending on the purpose of utilization, different types of machines are used for the shredding of pruning residues. Conducting research on the aspects to consider in the manufacturing and operation of these machines would be beneficial. This study aims to determine the operating parameters of a pruning residue chooper machine equipped with a collection and sieving unit, taking into account previous studies and practical requirements. Three independent experiments were conducted using olive and vineyard pruning residues, considering three different moisture contents (N1, N2, N3) (45%, 35%, 20% for olives and 55%, 35%, 25% for vineyards), three different rotor speeds (S1, S2, S3) (1200, 1500, and 1800 1/min), and two different blades (B1 and B2) (hammer and designed blade). The obtained data were analyzed in terms of the most suitable application conditions, energy consumption, and shredding efficiency. Additionally, using the determined specific energy requirements (kWh/ton) and machine capacity (ton/h), the operating costs of the machine were estimated. According to the findings of the study, the increase in rotor speed and decrease in material moisture content positively affected the success of the shredding process in terms of low energy consumption, high machine capacity and high shredding efficiency in the shredding of olive pruning residues. In olive pruning residues, the most successful shredding process was obtained at S3 rotor speed (1800 1/min) and N3 moisture content (25%) for dry material. The lowest total machine cost per unit mass values were calculated as 166.8 TL/ton for the B1 blade and 159.9 TL/ton for the B2 blade under the specified conditions. It was determined that the B2 blade generated an average cost of 5.9% lower than the B1 blade. Regarding vineyard pruning residues, an increase in rotor speed resulted in a decrease in specific energy requirement, while increasing machine capacity and choopering efficiency. In contrast to the results obtained from olive pruning residue experiments, in the case of vineyard pruning residues, a decrease in moisture content from N1 to N2 increased specific energy consumption and decreased machine capacity. However, when the moisture content decreased from N2 to N3, specific energy requirement decreased, and machine capacity increased. The optimum machine performance for vineyard pruning residues was achieved with S3 rotor speed (1800 1/min) and N3 moisture content (20%). The lowest total machine cost per unit mass in the shredding of vineyard pruning residues compared to the dry base was determined as 179.6 TL/ton for B1 knife and 174.8 TL/ton for B2 knife at the end of the shredding process carried out at S3 rotor speed and N3 moisture content. According to the calculations, for all trials, the B2 blade cost 7.7% less than the B1 blade on average on dry material.