Increasing the flow capacity of hoses with electrical-heater coils to supply thickened preservatives for spraying

Introduction. Anticorrosion protection of agricultural machinery working elements is provided through using pneumatic application of thickened preservatives with heating. For this purpose, a wire coil is inserted inside the preservative-supply hose and connected to a current source. It is known that the wire thickness and the coil pitch affect the hydraulic resistance to fluid flow. However, it has not been established how the diameter of the coil insert and its heating affect the flow capacity of the flexible hose channel. The purpose of the research is to increase the capacity of a flexible hose with an electrical-heater coil. For this purpose, it is necessary to determine its geometric parameters minimizing the hydraulic resistance to the thickened preservative flow and reducing the energy consumption for heating the material in the hose. Materials and Methods. It is proposed to investigate two electrical-heater coils of the same length, but of different diameter, made of steel welding wire pieces of equal length. There was developed a stand to study the influence of the inserted coil parameters on the hose hydraulic resistance. The stand was used to determine pressure losses in hoses with coils and in smooth hoses when used engine oil and thickened preservative flow through them. The flow capacity of the hose with cold and heated coils was estimated. Results. The method of heating the preservative in the hose wall layer is justified. At the same time, its flow capacity increases one and a half times with less energy consumption (2.4 times) than when heating the preservative in the central part of the hose. Under laminar flow mode, the pressure loss in the hose is 2 times lower when the coil is equal to 0.85 of the hose channel diameter than when the coil is equal to 0.67 of the channel diameter. Discussion and Conclusion. The research found the rational way of placing the electrical coil near the heated hose channel wall. At low air temperature, the reduction of the thickened preservative viscosity by heating in the hose helps to decrease the pressure loss up to 50% and increase its flow capacity by 1.4-2.0 times. The use of a electrical-heater coil in the hose with thickened preservative will minimize energy consumption when preserving equipment on open storage sites.