The Performance Investigation Of Separation Type Heat Pipe And Its Application In Compounding Extrusion Granulator Unit

The separation type heat pipe based on the ordinary heat pipe technology is a highly efficient heat transfer technology for some special purpose. The difference between the separated type heat pipe and the traditional heat pipe is separated the evaporation and condensation sections forming a closed loop by pipeline. Due to its structural characteristics, the evaporation and condensation sections of the separation type heat pipe heat exchanger can be arranged flexibly according to the space and structure and achieve long-distance transmission of heat, which number can be set on request, so the separated type heat pipe in the practical industrial application is more adaptive than ordinary heat pipe. Since the1980s, the separation type heat pipe in such aspects of basic theory research and application research has made great development, widely used in waste heat recycling fields of chemical industry, metallurgy, environmental protection, petroleum, power generation and other high energy consumption enterprises.The system of compounding extrusion granulator unit is the key equipment in the petrochemical industry producing polyolefins, and polyolefins have become the organic synthetic materials owning the world’s largest share. The development of the mixing and granulating machine group hovering in the stage of the low production and low level in our country, large mixing extruding and granulating machine relying on foreign imports all the time have become a long-term pain of China’s plastic and petrochemical industry. Machinery manufacturing enterprises in China have been committed to realize the localization of large mixing and granulating machine group. Twin-screw extruder is an important component of the large mixing extruding and granulating machine group, responsible for the preheating, shear extrusion material, fully mixing and plasticizing modification and a series of important link, with large production, extruder’s screw keeps a high speed rotation for a long time, generating excess heat due to shear friction. Currently air cooling or water cooling is a main way of cooling for the extruder. Air cooling is suitable for small and medium-sized extruder, while water cooling is uneven and cavitation will appear causing equipment vibration with a increasingly exchanging heat.The main contents of this paper consist of three parts, first is to research heat transfer mechanism of the separation type heat pipe condenser based on the Nusselt laminar filmwise condensation; Second, using the VOF model to complete simulation of condensation; Last is to design the separation type heat pipe heat exchanger used for barrel’s heat exchanging of large mixing extruding and granulating machine group according to heat transfer characteristics of the separation type heat pipe.In this paper, Nusselt laminar membrane theory of the vertical wall is used to explain heat transfer process of condensation section of the separated heat pipe, considering the influence of steam velocity, gas-liquid interfacial shear stress, density and the separated heat pipe diameter on the process of condensation and heat transfer. Based on Nusselt laminar membrane theory, build correction model of explaining condensation section of the separated heat pipe, infer expression of the various parameters on describing condensation section of the separated heat pipe, using Simpson quadrature formula and Runge-Kutta derivation formula for discrete expressions and finally solve by MATLAB programming. Compare the results of correction model with those of Nusselt model, proving that the proposed correction model numerical solution is closer to actual condensation process than Nusselt model.Achieve the source term by analysis the condensation mechanism, and use UDF to complete simulation of condensation process. Then analysis the characteristic of flim flow.With the heat transfer mechanism’s study of the separated type heat pipe, according to the way of heat transfer and structure of large mixing extruding and granulating machine group, this paper eventually aim at putting forward a set of reasonable design of the separation type heat pipe, applying the excellent characteristics of the separation type heat pipe in heat transfer to heat exchanging of the system of compounding extrusion granulator unit.