Study on the fiber fouling in drying exhaust heat utilization of wood industry

Nanjing Forestry University ;

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Abstract

Based on the viscoelastic and creep deformation properties, a new deposition mechanism model for slender wood fiber particles in wast heat utilization is proposed in this paper. And the equivalent sphere method is used to describe the particle feature size in the model. With the proposed deposition model of flexible slender particles, the critical criteria are obtained. The influence of particle size, aspect ratio and damping factor on particle deposition has been investigated. The results indicate that particle deposition increases with the particle size decrease, aspect ratio and damping factor increase. According to the present deposition model, a coupling simulation with FLUENT and EDEM method was carried out for the flow field of fiber drying tail gas in heat piping exchanger, which indicated that particle deposition mainly occurred at the central windward area of fin due to the direction changer and the magnitude decrease of collision velocity between fiber particles and wall. Experiment of heat recovery of drying tail gas revealed that using the H fin tubes instead of rectangular fin tubes can greatly relieve the deposition of wood fiber particles, which provided a useful way to save energy in wood industries.