冷却单螺杆内聚合物熔体传热模型

基于聚合物熔体在冷却单螺杆内传热，引入平均温度表征螺槽深度方向的熔体温度变化，将黏性生热简化为内热源，建立聚合物熔体传热理论分析模型；基于模型分析了冷却单螺杆的结构参数与工艺参数对聚合物熔体冷却过程的影响规律，并通过计算流体动力学（CFD）模拟验证模型的准确性。结果表明，当螺槽深度为5~9 mm、螺纹升角为30°~50°时，通过增大螺槽深度和螺纹升角，同时降低螺杆转速和减少产量，能够有效增强冷却单螺杆内聚合物熔体的冷却效果，此时模型能够满足冷却单螺杆内聚合物熔体的降温需求。数值模拟值与模型计算值的最大相对误差为1.21%，表明聚合物熔体传热模型能够预测冷却单螺杆内聚合物熔体的冷却过程，可以为串联挤出发泡系统中冷却单螺杆的设计提供一定的理论参考。

Heat transfer model of a polymer melt in a single cooling screw

In the light of the heat transfer of a polymer melt in a single cooling screw, the average temperature has been employed as a parameter to characterize the melt temperature change in the direction of the screw channel depth. The viscous heat generation process was simplified as an internal heat source, and a theoretical model of the heat transfer in the polymer melt was established. Based on the model, the influence of structural parameters and process parameters of the single cooling screw on the cooling process of polymer melt was analyzed. Finally, the accuracy of the model was verified by computational fluid dynamics (CFD) simulations. The results show that cooling of the polymer melt in a cooling single screw can be effectively enhanced by:(i) increasing the depth of the screw channel and the helix angle of the screw, when the depth of screw channel is 5-9 mm and the helix angle of the screw is 30°-50°; (ii) decreasing the screw speed and output. The model can meet the cooling demands of a polymer melt in a cooling single screw. The maximum relative error between the numerical simulations and model calculations was 1.21%, indicating that the heat transfer model of a polymer melt can predict the cooling process of the polymer melt in a cooling single screw, and can provide a theoretical reference for the design of cooling single screws in series extrusion foaming systems.