Experimental studies on the pressure drop and holdup for cocurrent upwards (turbulent-turbulent) flow of air-liquid systems through copper coils are presented. A new correlation for the two-phase frictional pressure drop is proposed based on the modified Lockhart-Martinelli parameter φG2-1 in terms of dimensionless groups. © 1984.

K. Rangacharyulu

Gerard S. Davies

Liquids

AIR-LIQUID FLOW

HELICAL COILS

LOCKHART-MARTINELLI

PRESSURE DROP AND HOLDUP

Flow of fluids

gas liquid

Multiphase flow

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IIT Madras

Pressure drop and holdup studies of air—liquid flow in helical coils

The Chemical Engineering Journal

Helically coiled heat exchangers, where one of the working fluids is flowing through helical coil, are used in various process industries due to better heat transfer characteristics and the resulting compact layout. Out of these, process requirements make some of the heat exchangers to operate in air-water two-phase region. Even though the characteristics of their operation with single-phase working fluids are well documented, it is not so for the case of two-phase flows. There do exist few experimental results on hydrodynamics of air-water flow through helical pipes. However numerical investigation, which can give much insight into the physics of the problem, is lacking and this is the subject matter of this paper.Two-fluid Eulerian-Eulerian scheme available in FLUENT 6.3 is used in this analysis. Pitch circle diameter and pitch of the coil influence the nature of flow through helical coils. Another factor affecting the nature of two-phase flow in helical pipes is the diameter of the pipe. CFD analysis has been carried out by varying these parameters and their influence on thermal hydraulic characteristics of the two-phase flow are brought out. Subsequently analysis has been carried out by changing the inlet void fraction for a given value of the flow velocity. From these analyses, it has been established that correlations for heat transfer and pressure drop shall take into account the pitch circle diameter, pipe diameter and void fraction at the inlet. © 2009 The Institution of Chemical Engineers.

Chemical Engineering Research and Design

Thermal hydraulic characteristics of air-water two-phase flows in helical pipes

Investigations have been carried out to evaluate the two-phase frictional pressure drop for gas-non-Newtonian liquid flow through helical coils in vertical orientation. The experiments performed using nine coils and four different non-Newtonian liquids. The effects of gas and liquid flow rate, coil diameter, and liquid properties on two-phase frictional pressure drop have been illustrated. An attempt has been made to fit the experimental two-phase frictional pressure drop data by the Lockhart and Martinelli [R.W. Lockhert, R.C. Martinelli, Proposed correlation of data for isothermal two-phase two components flow in pipes, Chem. Eng. Prog. 45 (1949) 39-48] correlation and the modified Lockhart-Martinelli correlation as presented by different authors. In another approach, friction factor method was adopted to correlate the experimental data by dimensional analysis. The correlation developed predicts the two-phase frictional pressure drop with acceptable statistical accuracy. © 2007 Elsevier B.V. All rights reserved.

Chemical Engineering and Processing: Process Intensification

Two-phase frictional pressure drop of gas-non-Newtonian liquid flow through helical coils in vertical orientation

Experimental investigations have been carried out to evaluate the two-phase pressure drop and the holdup for flow through helical coils. The coils were made of thick wall transparent PVC tube of diameter 0.01 m and 0.013 m. 24 coils were made at different coil diameter and different helix angles (0° to 12°). Three different liquids were used for the experimental studies and air was the gas. Empirical correlations have been developed to predict the two-phase friction factor and the liquid holdup as functions of the physical and dynamic variables of the system. Statistical analyses of the correlations suggest that they are of acceptable accuracy.

Korean Journal of Chemical Engineering

Gas-Liquid Flow through Coils

Experimental investigations have been carried out to evaluate the two-phase pressure drop and the hold-up for gas-liquid flow through vertical helical coils. The coils were made of thick-walled transparent PVC tubes of diameters 0.01 and 0.013 m. Twenty-four coils were made with different coil diameters and different helix angles (0- 12°). Three different liquids and air were used for the experimental studies. Empirical correlations were developed to predict the two-phase friction factor and the liquid hold-up as functions of the physical and dynamic variables of the system. Statistical analysis of the correlations suggests that they are of acceptable accuracy.

Industrial and Engineering Chemistry Research

Gas-liquid flow through helical coils in vertical orientation

Experimental investigations have been carried out to evaluate the two-phase pressure drop and the holdup for gas-Newtonian liquid flow through helical coils. 24 helical coils and three different liquids were used for the experiments. Empirical correlations have been developed to predict the two-phase friction factor and the liquid holdup as functions of various physical and dynamic variables of the system. Statistical analysis of the correlations suggests that they are of acceptable accuracy.

Canadian Journal of Chemical Engineering

Gas-liquid flow through helical coils in horizontal orientation

International Journal of Multiphase Flow

An extension of the Lockhart-Martinelli theory of two phase pressure drop and holdup

Separated flow models—I. Analysis of the averaged and local instantaneous formulations

Chemical Engineering Science

Two phase flow—I. Pressure drop and void fraction measurements in concurrent gas-liquid flow in a coil

The Canadian Journal of Chemical Engineering

Studies on cocurrent gas-liquid flow in helically coiled tubes. I. Flow patterns, pressure drop and holdup

Industrial & Engineering Chemistry Process Design and Development

Two-Phase Flow in a Coiled Tube. Pressure Drop, Holdup, and Liquid Phase Axial Mixing

Pressure drop and holdup studies of air-liquid flow in helical coils

Journal	The Chemical Engineering Journal
ISSN	03009467
Open Access	No