Study of the modernized single-screw extruder body energy efficiency

Abstract

The subject of the study is the energy efficiency of the polymer extrusion process in a single-screw extruder for the polymer materials processing. The purpose of the research is to improve the design of the feeding section of the single-screw extruder cylinder, which consists in placing thermal paste in the gap between the connecting cylindrical surfaces of the removable cylindrical sleeve and the channel of the feeding section cylinder, which reduces the thermal resistance of the section wall and improves heat transfer from the processed material to the cooling water, and therefore, it makes it possible to reduce its consumption. To check the energy efficiency of the proposed technical solution, thermal calculation of the basic and modernized structures of the feeding section cylinder was performed in the Steady Thermal model of the Ansys program. Polyvinyl chloride brand SorVyl G 2171/9005 11/01 was chosen as a recyclable polymer, alloy steel as the material of the feeding section elements, and thermal paste with a thermal conductivity of 4 W/(m·K) as a filler for the annular space between the cylinder and the sleeve. The analysis of the calculations showed that the use of thermal paste instead of air in the gap between the cylinder and the removable cylindrical sleeve reduces the thermal resistance of the cylinder wall by 9 %, while with the traditional method of assembling the extruder body, the temperature on the inner surface of the sleeve was 67.5 °C, and under the condition application of thermal paste – 61.5 °C. At the same time, the temperature field along the length of the feeding section of the cylinder is also equalized. In addition, it is worth noting that the type of thermal paste used has almost no effect on the thermal resistance of the section wall, so in the proposed design it is possible to use low-cost thermal paste (replacing the thermal paste with a thermal conductivity of 4 W/(m·K) with a more effective one with a thermal conductivity of 8.4 W/(m·K) reduced the temperature on the inner surface of the sleeve by only 1 K). The proposed improvement of the feeding section of the cylinder of a single-screw extruder can be applied not only in the polymer processing industry, but also in the food and processing industries in the construction of screw machines for various purposes. Reducing the thermal resistance of the cylinder section wall of the single-screw extruder ensures a reduction in the flow of cooling water circulating in the cylinder channel and equalizes the temperature field along the length of the feeding section of the cylinder, and therefore prevents premature melting of the polymer and ensures reliable generation of pressure in the working channel of the extruder.