Experimental Pressure Drop Data Research Articles

Pressure drop prediction for R407C fluid during flow evaporation in horizontal pipes using Kalman Filter

The estimation of pressure drop in systems involving two-phase fluids holds a substantial influence over system design, energy efficiency, heat transfer dynamics, and the overall system performance. Existing correlations in the current literature exhibit considerable errors, primarily attributable to the diverse characteristics of flow patterns inside the pipe. This work presents a discussion on the pressure drop of the R-407C fluid in horizontal pipes during two-phase flow, along with the application of the Kalman Filter to improve the estimations produced by well-known correlations. The initialization data used were obtained through equations created based on experimental data and considering the influence that diameter, mass velocity, and saturation pressure have on the pressure drop. The correlations used as a basis for the calculations were selected from the literature, considering the lowest percentage error observed in the pressure drop estimation. Experimental data of pressure drop where compared with the results the obtained by using the correlation alone and in combination with a Kalman Filter. For tubes with a diameter greater than 1.5 mm, applying the correlation together with the Kalman Filter resulted in a Mean Absolute Relative Deviation (MARD) of 15.71, whereas using the correlation alone yielded a MARD of 28.26. For tubes with diameters of 1.5 mm or less, the MARD values were 12.12 and 62.90, for the combination of correlation and the Kalman Filter and for the correlation alone, respectively. These results underscore the viability of the Kalman Filter as an effective tool for improving the accuracy of pressure drop calculations in horizontal tubes.

Experimental Study on Heat Transfer Enhancement of 3D-Printed Mini Tubes Under Three Different Flow Directions

In this study, 864 heat transfer experimental data points and 216 pressure drop experimental data points were used to compare the heat transfer and friction factor behavior of 3D-printed and traditional tubes under uniform wall heat flux boundary condition. Experiments were conducted in the entire flow region that covers laminar, transition, and turbulent regions. The inside diameter of the test tubes is around 2 mm, and the average inside wall surface roughness for traditional and 3D-printed tubes is 2.211 μ m and 35.249 μ m , respectively. Comparing with the traditional tubes, in the upper transition and the turbulent regions, the Nusselt numbers and Colburn j -factors of the 3D-printed tube under three different flow directions were enhanced by an average of 52.67% and 51.59% respectively. The greater relative roughness of the 3D-printed tube enhanced the heat transfer but also increased the pressure drop significantly. The friction factors for the 3D-printed tube in these regions also increased by an average of 154.44% compared with the traditional tube. The results also show that the effect of different flow directions on heat transfer and pressure drop of the 3D-printed tube is insignificant relative to roughness. Moreover, the 3D-printed tube has an earlier transition compared with the traditional tube.

Comparative Study of Air–Water and Air–Oil Frictional Pressure Drops in Horizontal Pipe Flow

Experimental data for frictional pressure drop using both air–water and air–oil mixtures are reported, compared and used to evaluate predictive methods. The data were gathered using the 2-inch (54.8 mm) flow loop of the multiphase flow facility at the National University of Singapore. Experiments were carried out over a wide range of flow conditions of superficial liquid and gas velocities that were varied from 0.05 to 1.5 m/s and 2 to 23 m/s, respectively. Pressure drops were measured using pressure transducers and a differential pressure (DP) cell. A hitherto unreported finding was achieved, as the pressure drop in air–oil flow can be lower than that in air–water flow for the higher range of flow conditions. Using flow visualization to explain this phenomenon, it was found that it is related to the higher liquid holdup that occurs in the case of air–oil around the annular flow transition and the resulting interfacial friction. This additional key finding can have applications in flow assurance to improve the efficiency of oil and gas transportation in pipelines. Models and correlations from the open literature were tested against the present data.

A New Methodology to Evaluate the Sealing Process Based on Pressure Drop and Fluid Loss in Fractures during the Drilling Operation

Summary Natural or artificial fractures are common in the wellbore during drilling operations. These fractures allow the flow of drilling fluid into the rock formation. The loss of circulation increases the operation’s cost and nonproductive time, which may threaten the well’s structural integrity. To overcome this problem, it is necessary to understand the flow of fluids through fractures and develop methods to mitigate the loss of circulation. This work’s main contributions are expanding the knowledge on the flow of drilling fluids through fractured channels, conducting an experimental study on the flow of suspensions of lost circulation materials (LCM) in fractures, and performing a theoretical analysis to obtain mathematical models describing fractured channels’ sealing. This work proposes a correlation between the pressure drop and the volumetric flow rate of fluid through fractures. To validate the model, a physical simulator collected fluid flow data and pressure drop in fractures with 2-mm, 5-mm, and 10-mm apertures and 1.02-m length. A blend of polymers and calcium borate was used in suspension in water viscosified with xanthan gum (XG). Density and rheological behavior tests were performed to characterize the studied fluids. The LCM had a bimodal particle-size distribution, and the formulated fluids had a Herschel-Bulkley rheological behavior. Pressure drop, flow rate, and rheological data were used to propose a correlation between pressure drop and volumetric flow rate through the fracture. The proposed correlation was used to monitor the sealing of fractures by calculating their hydraulic diameter throughout the sealing process. The LCM suspensions underwent filtration tests to observe the effects of sealing particles on the mudcake and filtrate volume. The proposed correlation fitted the experimental data with less than 10% deviation. The fracture hydraulic diameter was estimated using experimental data of volumetric flow rate and pressure drop, which made it possible to monitor the sealing process of fractures through time. The sealing and filtration tests showed that the borate and polymer blends are effective as filtration control agents and LCM.

Flow boiling heat transfer coefficient and pressure drop of R448A inside various multiport tubes: An experimental investigation and correlation assessment

R448A, a safety class A1 a-zeotropic refrigerant blend with a GWP of 1390, is considered an efficient and environmentally friendly substitute for R404A in direct-expansion commercial refrigeration systems. Herein, we experimentally investigate the flow boiling heat transfer and pressure drop of R448A inside a multiport mini-channel tube. The experimental ranges of mass flux and heat flux are 100–500 kg/m2s and 3–15 kW/m2, respectively, and they cover the entire quality range at three different saturation temperatures of 3, 6, and 10°C. Three different test tubes are utilized in this study to evaluate the effect of tube geometry on the heat transfer, and their diameters range from 0.831 to 1.14 mm. The results show that mass flux has favorable effects on the heat transfer coefficient and pressure drop, while heat flux has a favorable effect on the heat transfer coefficient at low mass fluxes. As the saturation temperature decreases when the mass flux is high, the heat transfer coefficient and pressure drop increase. The tube with largest perimeter but the smallest hydraulic diameter has the highest heat transfer coefficient under the low mass flux condition. Heat transfer coefficient and pressure drop experimental data were compared with the models in literature, and the results of our statistical assessment indicate that the pure fluid model modified to account for the mixture effect produces the best results. Meanwhile, most pressure drop models produce reasonably good predictions. Additionally, a new correlation is proposed to predict the heat transfer coefficient in practical applications.

Pressure drop of structured packing in pilot column and comparison to common correlations

Packed columns are widely used in the chemical industry such as absorption, stripping, distillation, and extraction in the production of e.g. organic chemicals, and pharmaceuticals. Pressure loss and pressure drop correlations are of special interest when it comes to the hydrodynamic properties of a column. The pressure loss across the column is of interest in the design phase when the size of the blower to drive the gas stream through the column has to be decided. The loading point and flooding point are also influenced by the pressure loss and the area of operation is determined from these points. This work examines four different correlations on pressure drop. The correlations are (i) Ergun’s equation (1952), (ii) an improved version of Ergun’s equation by Stichlmair, Bravo, and Fair (1989), (iii) an equation developed by Billet and Schultes (1999), and (iv) an equation by Rocha, Bravo, and Fair (1993). The complexity of the correlations is increasing in the mentioned order, Ergun’s equation being the simplest one. This study investigates if the more complicated correlations give better predictions to pressure drop in packed columns. This is determined by comparing the correlations to experimental data for pressure drop in a packed column with 8.2 m of structured packing using water as the liquid and atmospheric air as the gas. Seven experiments were carried out for determining the pressure drop in the column with liquid flows varying from 0 to 500 kg·h−1. At constant liquid flow, the gas flow was varied from approximately 10 to 70 kg·h−1. The pressure drop across the non-wetted column was best described by the correlation by Rocha et al. while the pressure drop for liquid flows from 100 to 500 kg·h−1 was, in general, best described by Stichlmair’s equation. For an irrigated column, the highest deviation was a predicted pressure drop 69.6% lower than measured. The best prediction was 0.1% higher than the measured. This study shows, surprisingly, that for a system of water and atmospheric air, complicated correlations on pressure drop determination do not provide better estimates than simple equations.

Free-mounted cooling plate multi-objective topology optimization method towards precision machine tool heat dissipation: An experimental and numerical study

Machining accuracy is reduced by precision machine tool thermal deformation. Currently, machine tool temperature and thermal deformation are usually controlled by optimizing original machine tool structure or using a cooling system. However, these methods are poor in generalization ability and convenience, and traditional cooling channels have shortcomings of a large flow resistance and low heat transfer efficiency. In this study, a cooling plate multi-objective topology optimization method towards precision machine tool heat dissipation is proposed. Firstly, multi-objective topology optimization model is established with maximum heat exchange and minimum fluid dissipation energy as objective function. Then effect of various design parameters on topology optimization results is investigated. Penalty factor and design Reynolds number are taken as design variables, and heat dissipation and flow performances of different topology optimization results are analyzed. Response surface model is constructed, and then an analytical model of average temperature in design domain and pressure drop generated by Pareto fronts under different working conditions are obtained. Furthermore, a full-size three-dimensional thermal-fluid interaction verification model is constructed, and cooling and flow performances of topology optimization cooling plate are compared with those of traditional spiral cooling plate. Numerical results show that cooling performance of topology optimization cooling plate is stronger than that of spiral cooling plate at high Reynolds number, and pressure drop of topology optimization cooling plate is reduced by 85.38% compared with that of spiral cooling plate. Finally, topology optimization and spiral cooling plates are manufactured, and experimental platform is built to evaluate heat dissipation and flow performances of cooling plates. For topology optimization plate, maximum deviations between simulation results and experimental data for temperature and pressure drop are 4.8% and 6.4%, respectively. The effectiveness and feasibility of the topology optimization design for cooling plate are verified.

Rheological properties of CO2 hydrate slurries in presence of Dioctyl sodium sulfosuccinate (AOT) in a dynamic loop for refrigeration application

Recent studies have shown real potential for using hydrate slurries as a secondary fluid in indirect refrigeration systems. However, pipeline clogging problems can appear due to hydrate agglomeration. Additives are generally used to counteract these problems. In this study, rheological properties of CO2 hydrate slurries in the presence of an additive Dioctyl sodium sulfosuccinate (AOT) are investigated. The capillary viscometer method is used to determine the fluid behaviour and the AOT impact on the slurry rheology. A dynamic loop is set up to collect experimental pressure drop and volume flow rate data. Based on the Rabinowitch and Mooney approach and Herschel-Bulkley model to determine the rheological properties, a shear-thinning behaviour was observed. The importance of the behaviour index choice in the procedure is discussed. Finally, the results obtained with AOT are compared with pre-existing studies. The present study highlights the AOT potential to significantly improve the CO2 hydrate slurries properties.

Experimental investigation on flow condensation pressure drop of R134a in microfin tube at high mass flux

Abstract To clarify the influencing mechanisms of the experimental condition and the tube structure on the pressure drop of heat transfer fluid, the two-phase flow condensation pressure drop of R134a inside the microfin tube was experimentally studied at high mass flux, which is different from other conventional researches. The experimental result shows the pressure drop is proportional to mass flux and fin helical angle, and is inversely proportional to condensation temperature and coolant Reynolds number. Moreover, the experimental data of pressure drop was compared with the predicted value of some existing correlations for the microfin tube. It can be found that the correlations of Cavallini et al., Han et al. and Haraguchi et al. show a good prediction effect with mean relative deviation (MRD) of 13.89, 16.08 and −2.19%, respectively. The correlations of Pierre/0.053, Kedzierski et al. and Choi et al. all underestimate most of the experimental data of the pressure drop inside the tube, and their prediction deviations are >10%. That is, the application effect of the separated flow model is better than that of the homogeneous flow model. Finally, the Kedzierski et al. correlation was improved to realize a high-precision prediction of the fluid flow mechanism inside the tube. Because the prediction deviation of the improved correlation between the experimental value and the predicted value was greatly reduced, its prediction deviation is <10% for R134a and R410A; therefore, it can be said the improved correlation has a good predictive result for the pressure drop.

Validation of a Lumped Parameter Model of the Battery Thermal Management System of a Hybrid Train by Means of Ultrasonic Clamp-On Flow Sensor Measurements and Hydronic Optimization

Electrification of the field of transport is one of the key elements needed to reach the targets of greenhouse gas emissions reduction and carbon neutrality planned by the European Green Deal. In the railway sector, the hybrid powertrain solution (diesel-electric) is emerging, especially for non-electrified lines. Electric components, especially battery power systems, need an efficient thermal management system that guarantees the batteries will work within specific temperature ranges and a thermal uniformity between the modules. Therefore, a hydronic balancing needs to be realized between the parallel branches that supply the battery modules, which is often realized by introducing pressure losses in the system. In this paper, a thermal management system for battery modules (BTMS) of a hybrid train has been studied experimentally, to analyze the flow rates in each branch and the pressure losses. Since many branches of this system are built inside the battery box of the hybrid train, flow rate measurements have been conducted by means of an ultrasonic clamp-on flow sensor because of its minimal invasiveness and its ability to be quickly installed without modifying the system layout. Experimental data of flow rate and pressure drop have then been used to validate a lumped parameter model of the system, realized in the Simcenter AMESim® environment. This tool has then been used to find the hydronic balancing condition among all the battery modules; two solutions have been proposed, and a comparison in terms of overall power saved due to the reduction in pressure losses has been performed.

Numerical analysis of hydrodynamic and thermal characteristics of three inside channel configurations of a plate and shell heat exchanger (PSHE)

The Plate and Shell Heat Exchanger (PSHE) is a variation of the Plate Heat Exchanger (PHE) with a more compact and robust geometry. This paper presents the analysis of the flow in the inner channel formed by a pair of plates of a PSHE employing computational fluid dynamics to determine the hydrodynamic and thermal characteristics for three Chevron angle configurations, 15° × 15° (High/High-HH), 45° × 45° (Low/Low-LL) and 15° × 45° (High/Low-HL). The ANSYS CFX software was employed with the application of the Standard k-ε and the SST (Shear-Stress-Transport) turbulence models for comparison. Experimental pressure drop data and flow streamlines were used to validate the numerical model and to analyze simplifications in the geometric model. Pressure drop, friction factor, and Nusselt number were evaluated for the three geometries studied. A local analysis of the parameters that describe the channels was also performed in this study.

Implementation of a CFD methodology for computing subchannel friction factors and split parameters in wire-wrapped rod bundles

A Computational Fluid Dynamics (CFD) model is presented to simulate an isothermal flow within a 61-pin wire-wrapped fuel assembly, typically employed in Liquid Metal Nuclear Reactors. A methodology is proposed to compute subchannels friction factors and split parameters, which are relevant variables for reactor licensing calculations and safety evaluations. Five subchannels are analyzed: three interiors, one on the edge and one at the corner. The model is validated with pressure drop experimental data of the different subchannels measured at the Texas A&M Thermal-Hydraulics Research Lab. The CFD pressure drop results are found in correct agreement with the experimental data. The subchannels parameters are compared with the predictions of the UCTD and PCTD correlations to evaluate their performance. Results indicate a reasonable agreement at turbulent regime, while the highest differences between the CFD model and the correlations are found at laminar regime. Therefore, the use of numerical simulations can be a suitable strategy for improving the correlations at low Reynolds numbers.

An improved prediction of frictional pressure drop using an accurate shear rate equation for high-yield stress drilling fluids at the surface and downhole conditions

This paper evaluates a more accurate and relatively new shear rate equation based on the phenomenological model for the high yield stress drilling fluids to estimate frictional pressure drop in laminar and turbulent flow regimes under surface and downhole conditions. Fann viscometer readings are used to determine shear rates using the above phenomenological model that differ from the conventional shear rates, i.e., γ˙(s−1)=1.7N, where N = Fann viscometer rotor rpm. The new shear rates are used to predict model parameters of Bingham plastic (BP), power-law (PL), Herschel–Bulkley (HB), and Robertson-Stiff (RS) models, and corresponding frictional pressure drops. The efficacy of the above rheology models with improved model parameters is tested by validating the literature-reported experimental pressure drop data of low to high yield stress water-based drilling fluids. The validation results are consistent and accurately predict frictional pressure drops using HB and RS models with the lowest MSE-values. The above methodology is applied to predict frictional pressure drops in a pipe for ten test high-pressure, high-temperature (HPHT) drilling fluids of varying base fluids at the surface and HPHT conditions in laminar and turbulent flow regimes. For this, isothermal compressibility and thermal decomposition temperature of drilling fluids are measured to forecast the temperature- and pressure-dependent densities and shear viscosities. The proposed density model is experimentally validated and found to predict density at downhole conditions adequately with mean absolute- and standard-deviation, i.e., 1.67 and 1.36%, respectively. Temperature- and pressure-dependent viscosity and density have been used to predict pressure drop under downhole conditions using HB and RS models with improved model parameters from the phenomenological model. The HB model is found to be more accurate than the RS model for predicting pressure drop. The proposed frictional pressure drop estimation method in the present study is more general and accurate under the surface and downhole conditions than the conventional practice.

Theoretical and experimental analyses of two-phase flow condensation heat transfer inside the horizontal micro-fin tube

On the basis of previous experimental studies of two-phase flow condensation heat transfer for R134a inside the horizontal micro-fin tubes, a theoretically analysis of heat transfer characteristic combining both heat transfer mechanism and flow mechanism is discussed by the experimental data of heat transfer coefficient and pressure drop, to further clarify the influence of experimental condition and tube structure on heat transfer characteristics under the special working condition. Two performance factors, enhancement factor (EF) and penalty factor (PF), are introduced to quantitatively compare the effect of micro-fin on the heat transfer coefficient and the pressure drop between enhance tube and smooth tube. Meanwhile, the comprehensive factor, CHF, is applied to evaluate the comprehensive performance of heat transfer tube. It was found that enhancement factor (EF) and penalty factor (PF) both increase with increasing mass flux and fin helical angle, and decreasing saturation temperature, the comprehensive factor, CHF, is always greater than one and increases with increasing fin helical angle and mass flux, and decreasing saturation temperature. Moreover, based on the comparative analysis findings that some existing correlations of heat transfer characteristics underestimate most of the experimental data, and the experimental variable has great influences on the correlation prediction accuracy, such as mass flux, which is proportionate to the prediction deviation of correlation. Therefore, a new correlation was developed through analyzing quantitatively influencing mechanism of the experimental variable on the heat transfer characteristics, in a way that a two-phase frictional multiplier is defined firstly from the experimental data and then the forced convection heat transfer mechanism is redefined based on the comprehensive effect of various experimental variables. By the experimental data verification, the new correlation shows good prediction effect with the mean deviation of less than 5%.

Prediction of nanofluid heat transfer characteristic and pressure drop in helical coil via artificial neural networks

In this paper, experimental data of Nusselt number and pressure drop utilizing TiO2/water, ZnO/water, and Ag/water nanofluids in helical coils under isothermal conditions were used to design an artificial neural network to predict Nusselt number and pressure drop for experimental and predict data. Feed Forward Neural Network (FFNN) and Generalized Regression Neural Network (GRNN) were designed. All predicted results were compared with the original experimental data and the results showed that both networks could be used to predict Nusselt number and pressure drop. Root Mean Square Error (RMSE) was used to measure the accuracy of each neural network. Predicted Nusselt number average RMSE for FFNN and GRNN were 4.84 and 0.004, while expected Nusselt numbers were 4.009 and 0.63. Predicted pressure drop average RMSE for FFNN and GRNN were 6.78 and 0.005 respectively while the average RMSE for expected pressure drop were 6.173 and 0.105 respectively. GRNN showed more accuracy than FFNN. The maximum deviation between trained data and experimental data for FFNN and GRNN were ±15.5% and ±0.02%, respectively. The maximum deviation between predicted data and experimental data for FFNN and GRNN were ±13.1% and ±1.6% respectively. The generated networks to predict non-experimental data showed good and logical behavior and proved that they are sufficient in Nusselt number and pressure drop prediction.

Multi-scale modelling of fluidized bed biomass gasification using a 1D particle model coupled to CFD

For many fluidized bed applications, the particle movement inside the reactor is accompanied by reactions at the particle scale. The current study presents for the first time in literature a multi-scale modelling approach coupling a one-dimensional volumetric particle model with the dense discrete phase model (DDPM) of ANSYS Fluent via user defined functions. To validate the developed modelling approach, the current study uses experimental data of pressure drop, temperature and gas composition obtained with a lab-scale bubbling fluidized bed biomass gasifier. Therefore, a particle model developed previously for pyrolysis was modified implementing a heat transfer model valid for fluidized bed conditions as well as kinetics for char gasification taken from literature. The kinetic theory of granular flow is used to describe particle–particle interactions allowing for feasible calculation times at the reactor level whereas an optimized solver is employed to guarantee a fast solution at the particle level. A newly developed initialization routine uses an initial bed of reacting particles at different states of conversion calculated previously with a standalone version of the particle model. This allows to start the simulation at conditions very close to stable operation of the reactor. A coupled multi-scale simulation of over 30 s of process time employing 300.000 inert bed parcels and about 25.000 reacting fuel parcels showed good agreement with experimental data at a feasible calculation time. Furthermore, the developed approach allows for an in-depth analysis of the processes inside the reactor allowing to track individual reacting particles while resolving gradients inside the particle.

Laboratory validation of steady-state-transient test to determine relative permeability and capillary pressure

The work aims at the laboratory validation and practical implementation of the steady-state-transient method for simultaneous determination of relative permeability Kr and capillary pressure Pc, which uses steady-state data along with the transient data between the steady states. A new methodology for preliminary choice of Kr and Pc and the detailed test modelling yields planning and design of the steady-state-transient test SSTT – the definition of admissible flow rate, number of steady states and injected water fractions, frequency and volumes of the effluent samples. The test-parameter choice is based on the newly derived theoretical criteria for validity of the model for two-phase flow in porous media, and the operational criteria for the accuracy of the measurements. The preliminary modelling also allows determining the type curves for transient pressure-drop histories, which are used to approximate the measured data and input the inverse solver. Two laboratory SSTTs with inlet half-moon and concentric-circle distributors are carried out. The agreement between the matched-modelling and experimental data for pressure-drop is significantly higher than for average saturation for both tests. The agreement for the test with the concentric-circle distributor is significantly closer than that of the half-moon distributor. This is explained by non-uniform saturation distributions in core cross-sections due to 3D flow, which is more pronounced in the case of half-moon distributor.

An Experimental Study of Pressure Drop Characteristics and Flow Resistance Coefficient in a Fluidized Bed for Coal Particle Fluidization

Liquid–solid fluidized beds have a wide range of applications in metallurgical processing, mineral processing, extraction, and wastewater treatment. Great interest on their flow stability and heterogeneous fluidization behaviors has been aroused in research. In this study, various fluidization experiments were performed by adjusting the operating conditions of particle size, particle density, and liquid superficial velocity. For each case, the steady state of liquid–solid fluidization was obtained, and the bed expansion height and pressure drop characteristics were analyzed. The time evolution of pressure drop at different bed heights can truly reflect the liquid–solid heterogeneous fluidization behaviors that are determined by operating conditions. With the increase in superficial liquid velocity, three typical fluidization stages were observed. Accordingly, the flow resistance coefficient was obtained based on the experimental data of bed expansion height and pressure drop. The flow resistance coefficient experiences a decrease with the increase in the modified particle Reynolds number and densimetric Froude number.

Assessment of pressure drop in conical spouted beds of biomass by artificial neural networks and comparison with empirical correlations

Pressure drop is an essential parameter in the operation of conical spouted beds (CSB) and depends on its geometric factors and materials used. Irregular materials, like biomass, are complex to treat and, unlike other gas–solid contact methods, CSB turn out to be a suitable technology for their treatment. Artificial neural networks were used in this study for the prediction of operating and peak pressure drops, and their performance has been compared with that of empirical correlations reported in the literature. Accordingly, a multi-layer perceptron network with backward propagation was used due to its ability to model non-linear multivariate systems. The fitting of the experimental data of both operating and peak pressure drop was significantly better than those reported in the literature, specifically in the case of the peak pressure drop, with R2 being 0.92. Therefore, artificial neural networks have been proven suitable for the prediction of pressure drop in CSB.

Pressure drop and flow pattern of gas-non-Newtonian fluid two-phase flow in a square microchannel

An experiment of gas-non-Newtonian fluid flow was performed in a horizontal square microchannel to investigate the two-phase pressure drop and flow pattern. The pressure drops were measured and the images of the flow pattern were captured. In the non-Newtonian fluid, the flow pattern and flow regime map were different from those in water. The non-Newtonian behavior of the liquid phase also significantly affected the two-phase pressure drop. The relationship between the two-phase pressure drop and the gas and fluid flow rates relied on the flow pattern. A new two-phase friction multiplier correlation considering the gas-liquid flow rate ratio and the rheological properties of the liquid phase was developed to calculate the two-phase pressure drop. The new correlation can predict the experimental pressure drop data within the root mean square percentage errors of 12% for the gas-non-Newtonian fluid two-phase flow and 17% for the gas-water two-phase flow.