Flow and heat transfer model for turbulent-laminar/turbulent gas-liquid annular flows

Abstract

• Physical process of heat transfer for annular flow was mathematically formulated. • Effect of flow orientations and parameters on heat transfer process was analyzed. • Heat transfer was significantly enhanced by gas in flow regime of annular flow. • Dependence of heat transfer multiplier on void fraction and pressure drop multiplier was identified. • A heat transfer correlation was developed based on Chilton & Colburn analogy. Two-phase gas-liquid annular flows are characterized by the liquid flowing in the annular-shaped channels as liquid film and gas flowing in the center as gas core. Adequate understanding of the flow and heat transfer mechanism is important. This paper aims at developing a model for flow and heat transfer in two-phase annular flows. First, the physical process of flow and heat transfer for two-phase annular flow is mathematically formulated and a new heat transfer model is developed based on two-fluid concept. Then, the new model is well validated using the experimental void fraction, liquid film thickness, and heat transfer coefficient collected from various sources. Third, the effect of the orientations and flow parameters on the heat transfer of two-phase annular flows are comprehensively investigated. Finally, the dependence of the two-phase heat transfer multipliers on the void fractions and pressure multipliers is identified quantitatively and a simple heat transfer correlation is developed based on Chilton & Colburn analogy.