Two-Phase Flow Patterns and Flow-Pattern Maps: Fundamentals and Applications

Abstract

A comprehensive review of the studies of gas-liquid two-phase flow patterns and flow-pattern maps at adiabatic and diabatic conditions is presented in this paper. Especially, besides other situations, this review addresses the studies on microscale channels, which are of great interest in recent years. First, a fundamental knowledge of two-phase flow patterns and their application background is briefly introduced. The features of two-phase flow patterns and flow-pattern maps at adiabatic and diabatic conditions are reviewed, including recent studies for ammonia, new refrigerants, and CO2. Then, fundamental studies of gas-liquid flow patterns and flow-pattern maps are presented. In the experimental context, studies of flow patterns and flow-pattern maps in macro- and microscale channels, across tube bundles, at diabatic and adiabatic conditions, under microgravity and in complex channels are summarized. In addition, studies on highly viscous Newtonian fluids (non-Newtonian fluids are beyond the scope of this review) are also mentioned. In the theoretical context, modeling of flow-regime transitions, specific flow patterns, stability, and interfacial shear is reviewed. Next, flow-pattern-based heat transfer and pressure drop models and heat transfer models for specific flow patterns such as slug flow and annular flow are reviewed. Based on this review, recommendations for future research directions have been given.

Fundamental issues, mechanisms and models of flow boiling heat transfer in microscale channels

“…Cheng and Mewes [12] made a comparison of these different criteria for micro-scale channels. Figure 4 shows their comparable results for 11 water and CO 2 , which shows the big difference among these criteria. It is obvious that no general definition of micro-scale channels has been agreed so far.…”

“…However, it should be realized that the transition from macroscale-to-micoscale is a continuous and progress process which corresponds to the flow regime, heat transfer behaviors and mechanisms. Therefore, the most important point is to relate flow regimes to flow boiling heat transfer behaviours such as heat transfer, CHF and fluid behaviour such as pressure drops as pointed out by Cheng et al [11].…”

“…[1][2][3][4][5][6]. It is nowadays one of the most important research subjects in the field of heat transfer with various industrial and practical applications for the past decades [7][8][9][10][11]. For instance, as a highly efficient cooling technology, it has a lot of advantages of high heat transfer performance, chip temperature uniformity, hot spots cooling capability for cooling electronic chips and elements [4,[12][13][14][15][16].…”

Modeling and design guidelines for direct steam generation solar receivers

“…In the engineering design of evaporators and steam generators, the wall-fluid heat transfer is more important in determining the thermal performance than the detailed in-tube liquid-vapor interfacial heat and mass transfer. Hence less computationally expensive 1D twofluid (separated or homogeneous) two-phase flow models with empirical correlations (single equation correlations [35,36] and flow pattern based correlations [37,38]) for the wall-fluid heat transfer coefficients are commonly employed [39][40][41] without resolving the local non-uniformity of the wall-liquid heat transfer. An obvious disadvantage of a simplified 1D two-phase model with empirical correlations is that the local heat transfer and temperature distribution cannot be accurately captured.…”

Research of Characteristics of Gas-liquid Two-phase Pressure Drop in Microreactor

“…The research of gas-liquid two-phase flow pressure drop must be done under a certain specific flow pattern, because the characteristic of gas-liquid two-phase flow pressure drop is different in different flow patterns [1][2][3] . The divided-phase flow pattern adopted by gas-liquid two-phase pressure drop in the conventional pipeline assumes that each phase of flow is continuous in two phases, and considers the interaction between two phases.…”