Study on Gas-liquid Two-phase Flow Patterns and Pressure Drop in a Helical Channel with Complex Section

Single screw expansion is widely used in petroleum and chemical department, energy recovery engineering, power engineering and many practical applications. Yet the problems of gas leakage in the single screw expansion seriously affect its efficiency. An experimental investigation of gas-liquid two-phase flow patterns and pressure drop inside the single screw expansion has been carried out. The flow patterns are distinguished and recorded by high speed camera using the backlight imaging tomography. The test section made of plexiglass is manufactured according the screw of single screw expander prototype whose diameter and length of are 155mm and 112mm. There are five flow patterns in the screw channel: bubbly flow, dispersed bubbly flow, slug flow, churn flow and annular flow. The flow pattern map of the test channel is presented and compared with the flow pattern map of typical available models. The effect of Re L and Re G on pressure drop is presented. Pressure frequency of four flow patterns and their PDF function are presented. Based on the experimental data a new correlation to predict the liquid multiplier factor of test channel is purposed.