Transportation of Wood Chips by Liquid Film Flow in Sloped Rough Terrain Pipelines

Abstract

The unused biomass such as residues left on forest floor and unused portions of farm crops is considered as an important domestic and renewable energy resource. The present study addresses the forestry biomass derived from logging and thinning operations in forests. Since most of the forests in Japan locate in the mountain region, the forestry biomass has not been used continually due to the difficulty in carrying residues out of the forest. In order to promote the utilization of forestry biomass, the efficiencies for the transportation across steep slopes have to be improved. In the present study, the new method to transport wood chips by means of liquid film flow in sloped pipeline is proposed. The transportation limit of wood chips is investigated by using the test section imitating the sloped rough terrain pipeline. The wood chips are stagnated in the downstream region of hydraulic jump, which causes blockage of wood chips in the tube. To predict the flow rate of transportation limit of wood chips at a given liquid flow rate, analytical model is presented. From the comparison with the experimental results, it is found that the transportation limit in the sloped pipeline with horizontal tube can be predicted by the present analytical model.