Experimental Investigation and Performance Evaluation of Isothermal Frictional Two Phase Pressure Drop Correlations in Vertical Downward Gas-Liquid Two Phase Flow

Abstract

The correct prediction of gas-liquid two phase pressure drop is of immense significance for proper sizing of industrial equipment and safety operations involved in chemical, energy and petrochemical applications. The hydrostatic component of the two phase pressure drop is predicted based on the accurate estimation of void fraction. However, there exists a complexity in correct estimation of the frictional component of two phase pressure drop owing to interfacial friction at dynamic gas-liquid interface. The present study is focused on the experimental measurements of gas-liquid two phase frictional pressure drop and the performance evaluation of eleven correlations for its prediction in vertical downward orientation. The experimental determination of two phase frictional pressure drop is carried out for a 0.01252 m I.D. pipe with surface roughness of 0.0000152 m using air-water as the fluid combination. Unlike most of the other studies centered towards annular flow, this experimental study is spanned over different flow patterns and the entire range of the void fraction. In addition to the experimental measurements, the scope of this study also includes the performance analysis of eleven frictional pressure drop correlations available in the literature. These correlations are those based on the separated flow model initially proposed by Lockhart and Martinelli [1].The available frictional pressure drop correlations are compared against the data measured in the present study. Based on the experimental data available in the literature, the influence of the pipe diameter and fluid viscosity on the frictional pressure drop is also analyzed.

Experimental Investigation and Empirical Analysis of Non-Boiling Gas-Liquid Two Phase Heat Transfer in Vertical Downward Pipe Orientation

“…On the basis of the deviation of the two phase pressure drop from its single phase counterpart as shown in Figures 5-9, it is clear that the parameter that increases with increasing gas flow rate might correlate the two phase and single phase heat transfer coefficients. Bhagwat et al [12] found the non-dimensional frictional pressure drop defined by Equation (2) to increase with increasing superficial gas Reynolds number (Re sg ) and with the trend similar to that observed for two phase heat transfer. The major advantage of using this form of the correlation based on the Reynolds analogy is that it accounts for change in the flow condition such as the pipe diameter and fluid combination through the (φ) parameter.…”

“…The problem with using Reynolds analogy is that it requires the frictional pressure drop data or a robust and accurate correlation to predict frictional pressure drop in different flow patterns. The isothermal frictional pressure drop data used to analyze Tang and Ghajar [1] correlation was obtained from the pressure drop measurements done by Bhagwat et al [12]. The Reynolds analogy given by Tang and Ghajar [1] is observed to predict the two phase convective heat transfer coefficient satisfactorily as shown in Figure 11.…”

“…The major advantage of using this form of the correlation based on the Reynolds analogy is that it accounts for change in the flow condition such as the pipe diameter and fluid combination through the (φ) parameter. It was observed by Bhagwat et al [12] that the two phase pressure drop is significantly influenced by the pipe diameter and the fluid thermo physical properties specially in the annular flow regime. It is anticipated that by using the (φ) parameter to correlate the two phase and single phase convective heat transfer coefficient, the influence of fluid combination and pipe diameter on the two phase heat transfer coefficient can be overcome.…”

Interfacial shear in adiabatic downward gas/liquid co-current annular flow in pipes

“…In this case the friction factor is termed a two-phase friction factor and in reality, such methods are flow regime independent notably in the style of Lockhart -Martinelli (1949). The works of Klausner et al (1991), Dalkilic et al (2009) and Bhagwat et al (2012) are cases in point. Hewitt & Hall-Taylor (1970) have shown using the data of Gill et al (1964) that the homogeneous model method is less accurate than flow regime specific methods.…”