Physico-Mechanical Properties of Pumpkin Seeds in the Context of Drying Processes

Abstract

The paper highlights the significance of the drying process in post-harvest cucurbit seed treatment technology. To improve the effectiveness of drying high-moisture seeds, a plant construction design was introduced, incorporating the concept of providing varied heat distribution to a vigorously agitated seed layer. The paper validates the necessity of refining the dimensional, frictional, and aerodynamic properties of pumpkin seeds to determine the optimal operating modes for the proposed dryer. (Research purpose) To identify the physical and mechanical properties of pumpkin seeds by defining their dimensional, frictional and aerodynamic characteristics. (Materials and methods) The study employs one-factor experimental research methods with subsequent statistical data processing. An experimental study was conducted on the physical and mechanical properties of Volzhskaya Grey pumpkin seeds possessing a standard moisture content ranging between 9.3 and 9.7 percent. Well-known laboratory apparatuses, namely the «conical tank» and the «inclined plane», were used to determine the natural repose angle and to enhance the accuracy of friction coefficients determination. For analyzing the aerodynamic properties of the seeds, the K-293 Petkus air separator was employed. (Results and discussion) Research methods were developed and experimental plants were described. It was established that with a probability confidence level of 0.95, the static friction coefficients of pumpkin seeds on a solid steel sheet, a perforated steel sieve and on rubber are 0.473, 0.418, 0.481, respectively, and the dynamic friction coefficients under the identical conditions are measured as 0.331, 0.293, 0.337. The average angle of natural repose is found to be 22 degrees, the midsection area is 97.94 square millimeters, the soaring velocity is 7.083 meters per second, the windage coefficient stands at 0.196 and the aerodynamic drag coefficient is 0.136. (Conclusions). The assumption that enhancing the drying efficiency of vegetable seeds can be achieved by implementing a diverse thermal energy supply to continuously moving mass inside the apparatus is confirmed, provided that the seeds do not stick together in layers resulting in blockage of the coolant flow. An improved design of the dryer configurations has been developed and, to validate its optimum design and technological specifications, an in-depth analysis of the seeds' dimensional, frictional, and aerodynamic attributes has been conducted.