滚塑工艺加热阶段的传热模型的解析解

Analytical Solution of Heat Transfer Model for Heating Phase in Rotational Molding Process

对从滚塑模具开始受热到其内部粉料开始熔融之间的加热阶段建立一个传热理论模型。在该模型中,忽略模具、内部空气和粉料的温度梯度,即各自只有一个随时间变化的平均温度。将模具的内部分成内部空气区域和粉料区域。内部空气和粉料在与模具发生对流换热的同时,这两者之间通过掺混也在发生对流换热。根据能量守恒原理,对模具、内部空气和粉料分别列出热能平衡方程式,然后通过简化和求解常微分方程组得到了它们平均温度的解析表达式。由此计算所得的内部空气温度与其实验结果吻合的较好,从而证明了此传热模型及其解析解的准确性。

In this work,we established a heat transfer model for heating phase in the rotational molding process from mold heating to powder melting.In this model,the temperature gradients of the mold,internal air and powder were ignored,and their average temperatures only varied with time.The space inside the mold was divided into the internal air region and powder region.Heat was transferred from the mold to both internal air and powders by convection,and meanwhile,heat was also transferred from internal air to powders by convection when they were mixing.The heat equilibrium equations for the mold,internal air and powders were presented on the basis of the principle of energy conservation.Furthermore,the analytical solutions for their average temperatures were obtained by simplifying and solving the differential equations.The internal air temperatures calculated from the analytical solutions were in good agreement with the experimental results,thus proving the validity of the heat transfer model and its analytical solutions.