Change In Pressure Loss Research Articles

Flow regime transition maps and pressure loss prediction of gas, oil and water three-phase flow in the vertical riser downstream 90° bend using data driven approach

The simultaneous flow of gas, oil & water is frequently encountered in pipelines during upstream petroleum operations. The multiphase flow results in different types of flow patterns based on the flow rates of fluids, physical properties and geometry of the flow domain. The flow behavior is characterized based on the governing flow patterns. Hence, the information about the flow patterns, regime maps and resulting pressure loss are important for multiphase flow system design and optimization. The current work is focused on construction of gas, oil and water, three-phase flow regime maps and developing pressure loss prediction correlations for the flow through vertical riser downstream 90° bend. The pipe internal diameter (ID) is 6 inch and the bending radius to pipe diameter ratio is 1. The observed gas-liquid flow patterns are slug, churn, and semi-annular churn flow at the given range of superficial velocities of fluids. The flow pattern data has been used to construct flow regime maps to analyze the variation in flow patterns with flow rates of fluids and compared with the available works in the literature. In addition, the change in pressure loss with respect to flow patterns has been analyzed. Previous models are used for the prediction of pressure loss. However, according to the assessment, the models underpredicted the pressure loss. Based on three-phase pressure loss data, multiple linear regression analysis has been carried out to propose new correlations for pressure loss prediction. Comparison of the calculated and experimental data showed good agreement between the results. The knowledge of flow regime variation and pressure loss correlations can help flow assurance engineers in designing and optimization of multiphase flow systems.

Analysis of dependences for hydraulic calculation of pipes made of polymer materials

Assess the influence of the equivalent roughness coefficient and roughness parameters on the value of the calculated pressure losses in pipelines made of polymer materials. Consider normalized calculation dependencies for the hydraulic calculation of pressure pipes made of polymer materials. Assess the difference in the pipeline hydraulic characteristics constructed using various formulas. Give recommendations on the choice of calculation dependence for determining the coefficient of hydraulic resistance, determining the specific pressure loss along the length for pipelines made of polymer materials. The dependence of the calculated specific pressure loss along the length on the equivalent roughness coefficient has been constructed. Hydraulic calculations were carried out using various calculation dependencies to determine the coefficient of hydraulic resistance of a pipeline with a diameter of 400 mm, made of PVCO 500, on a 1 km long section. The hydraulic characteristics of the pipeline are obtained and comparative results of calculating the values of specific pressure losses along the length when calculated using different calculation dependencies are presented. The magnitude of the change in pressure loss along the length is determined depending on the change in the value of the equivalent roughness coefficient. A calculation formula is recommended for determining the coefficient of hydraulic resistance for pipes made of polymer materials, taking into account the values of the height and step roughness parameters. Key words: polymer pipeline, pressure pipeline, roughness parameters, hydraulic calculation, pressure losses.

Phase Change and Heat Transfer Analysis of Different Refrigerants During Condensation in Minichannel Using a Novel Numerical Approach

Abstract This paper analyses the condensation heat transfer phenomena in minichannel using acetone, ammonia, propylene, and R134a as the working fluids used in new-age space applications. A novel numerical model is developed considering the changes in local vapor pressure in the channel established due to shrinking in the flow passage by the gradual formation of the liquid layer. The present developed numerical model is compared with the available numerical and experimental results. The impacts of different inlet mass fluxes (250, 500, and 750 kg/m2 s), channel heights (1, 4, 6, and 8 mm), applied heat loads (10, 100, 250, and 500 W), and channel orientations (0 deg, 30 deg, 45 deg, 60 deg, and 90 deg) on the performance of the condensation heat transfer process are investigated. The formation of the thin liquid film layers and evaluation of the liquid–vapor interface profiles are examined. The study reveals that the channel orientation has a marginal influence on the flow pattern for the considered channel length of 20 mm. The maximum change in pressure loss is found at the channel orientation of 45 deg, and the average heat transfer coefficient is almost the same for all the considered orientations. The flow pattern is affected by the increase in mass flux resulting in the delay of heat transfer coefficient fluctuations. The average heat transfer coefficient decreases with increasing heat load, and the minimum average heat transfer coefficient is obtained for heat load, Q = 500 W.

Computational fluid dynamic analysis of the flow field in the newly developed inflow cannula for a bridge-to-decision mechanical circulatory support

The flow field of the newly developed inflow cannula designed for a bridge-to-decision circulatory support was numerically analyzed by computational fluid dynamics. This new cannula has elastic struts at the tip that enable minimal invasive insertion into the left ventricle while maintaining a wide inflow area by its lantern-like tip. The cannula's hydrodynamic loss, including change in pressure loss due to deformation, and its thrombus potential were numerically examined. Hydraulic resistance of the cannula with blood analog fluid was 31 mmHg at the flow rate of 5.0 L/min. There were regions on the inner surface of the struts where the shear rate was <100 s(-1), and these regions can be a potential for thrombus formation, especially at low flow rates or under limited anticoagulant therapy.

The characteristics of spiral waves in an axially rotating pipe

An experimental study of the instability of a flow in an axially rotating pipe is performed by means of LDV and flow visualization technique. It is found that the axial velocity of the rotating pipe flow fluctuates like a sine wave at first, then its fluctuating pattern assumes a somewhat sawtooth wave form as a spiral wave appears, which is predicted by means of linear and nonlinear stability analysis. At a certain rotation rate, the amplitude of the velocity fluctuations amounts to 30% of the axial velocity. At the down-stream section, another fluctuating component appears in the velocity, which interferes with the initially appearing component, then the fluctuation becomes one with broad-band spectral components. There is a close analogy between this spectral evolution and that of a Taylor-Couette flow. Deformation of the velocity distribution is obtained from the velocity fluctuating pattern and its phase, and the structure of the spiral wave is considered. The strength, azimuthal wavenumber and angular velocity of the spiral wave obtained from the velocity data are confirmed by flow visualization. The change of pressure loss in the rotating pipe is compared with the case without rotation.