Pipe Of Inner Diameter Research Articles

Upward and downward two-phase flow of CO2 in a pipe: Comparison between experimental data and model predictions

In order to deploy CO2 capture and storage (CCS) systems to mitigate climate change, it is crucial to develop reliable models for design and operational considerations. A key element of the system is the interface between transportation and storage, namely the injection well, where various transient scenarios involving multiphase flow will occur.In the literature there are very few data relevant for validation of vertical multiphase flow models for CO2. Hence in this work, we present measurements of liquid holdup, pressure drop and flow regime for upward and downward flow of CO2 in a pipe of inner diameter 44mm at a pressure of 6.5MPa, a condition relevant for CO2-injection wells.The experimental results indicate that the flow is close to no-slip. We have compared the experimental data to predictions by well-known models for phase slip and frictional pressure drop, and the results show that overall, the best model is the simplest one – the fully homogeneous approach, in which no slip is assumed and the friction is calculated simply by employing gas-liquid mixture properties in the single-phase friction model.

Comparison of throttle devices to measure two-phase flowrates of wet gas with extremely-low liquid loading

The online measurement of wet gas with extremely-low liquid loading (Lockhart-Martinelli parameter lower than 0.02) remains a challenge. In this study, three types of throttle devices, Venturi, orifice plate and cone, are compared experimentally with air-water two-phase flow in a horizontal pipe of inner diameter of 50 mm. High-precision correlations are established to measure the gas and liquid flowrates via a single throttle device. Results show that the two-phase mass flow coefficient (K) of the three throttle devices all increase linearly with the liquid densiometric Froude number and the K correlations are established respectively to correct the gas mass flowrate deviation. The pressure loss ratio (δ) for Venturi is sensitive and monotonous to the liquid loading, which contributes to the high accuracy of liquid flowrate measurement. By incorporating the K correlations, both the gas and liquid mass flowrates can be predicted precisely. The relative error of the gas mass flowrate predicted by the Venturi is within ±2.0% at 95% confidence level, and that of the liquid mass flowrate is within ±15% at 90% confidence level.

Experimental studies of heat transfer and flow regimes during flow boiling of water and alumina nanofluids at different heat and mass fluxes

The flow boiling heat transfer in a vertical pipe of inner diameter 7.5 mm was investigated with pure water and Al2O3/water nanofluid as working fluids. The main heater section was made up of borosilicate glass for better visualization of flow regime. For this study, particle concentrations of 0.001%, 0.005% and 0.01% were considered. The influence of mass flux and heat flux, on flow boiling heat transfer was analysed. From the results, it is observed that boiling heat transfer coefficient is increasing with mass flux for both water and nanofluids. Use of nanofluid decreases wall superheat. The average reduction of wall superheat, as compared to water, at mass flux of 905.42 kg/s-m2 for 0.001%, 0.005% and 0.01% nanofluids is 10.8%, 21.34% and 26.79% respectively. It is also observed that heat transfer coefficient increases with particle concentration due to the changed heater surface characteristics and amendment in bubble formation mechanism. The average enhancement in heat transfer coefficient, as compared to water, for the particle concentrations of 0.001%, 0.005% and 0.01% at a mass flux of 905.42 kg/s-m2 is found to be 12.11%, 21.75% and 27.97%, respectively. Flow visualization study was also done to differentiate flow patterns of water and nanofluids. Churn flow regime was observed for water at moderate heat fluxes. However, in case of nanofluids, churn flow was not observed. The flow boiling heat transfer coefficient is observed to be high for the nanofluids compared to water. An effort has been made to explain the heat transfer mechanism, based on the existing flow boiling regime under the given conditions.

A New Model for Prediction of Liquid Holdup in Two-Phase Flow under Higher Gas and Liquid Velocities

Existing liquid holdup models are generally based on low gas and liquid velocities. In order to extend the applicable range of existing liquid holdup prediction models and improve its prediction accuracy, a of gas-liquid two-phase flow experiment was carried out using a pipe of inner diameter 60mm and length of 11.5m. The superficial gas and liquid velocity ranges were 14.07~56.50m/s and 0.205~1.426m/s, respectively. The results indicate that the liquid holdup decreases with the increase of the superficial gas velocity and increases with the increase of the superficial liquid velocity. A new annular flow model for calculating low liquid holdup in horizontal pipe was developed and presented considering the relationships between the friction factor ratio of liquid phase and gas-liquid interface as well as the superficial Reynolds number of gas and liquid. The predictions of the model are found to be accurate with an average absolute error of 4.8%. Further, on the basis of the Beggs-Brill model and the horizontal pipe model established in this paper, a new liquid holdup model for different angles was given. It was observed the resultant model is also accurate, and has an average absolute error of 10%.

Experimental Investigation on Effect of Fin Height on Microscale Heat Transfer and Fluid Flow for Macro Scale Industrial Applications

Microchannel for macro geometry application is gaining popularity particularly in aerospace, biomedical and photovoltaic. A novel method of employing microchannel in macro geometry at lower cost using conventional machining methods has been developed. A solid cylinder on outer diameter 19.4 mm is placed concentrically into a copper pipe of inner diameter 20 mm, forming an annular microchannel with 300 μm gap. This study takes a step further by introducing surface profile of different heights on the surface of solid cylinder and investigating the effect on two main design objectives- increasing heat removal capability at same pumping power and reducing pumping power for the same heat removal duty. Four surface profiles -parallel fins as well as fins with height of 0.1, 0.2 and 0.3 mm, were investigated experimentally at constant heat flux at Reynolds number from 690 to 4600. The amount of fluid in the microchannel, channel length of 30 mm, bifurcating angle of 75 degrees and mean hydraulic diameter of 600 μm are kept as constant parameters. A plain insert is used as benchmark for comparison of enhancement. In this study, insert with fins of 0.3 mm attains the highest enhancement of 43 percent increment in heat transfer as compared to plain insert using the same pumping power. While keeping the heat removal duty constant, the same insert is able to perform the duty using less than 50 percent the pumping power required by the plain insert at low Reynolds numbers.

Oil–water two-phase flow velocity measurement with continuous wave ultrasound Doppler

A flow velocity measurement method based on continuous wave ultrasound Doppler (CWUD) and flow profile modeling is presented. A theoretical model is proposed to relate the overall superficial velocity of oil–water two-phase flow with the mean velocity measured in the sensing volume of CWUD, by introducing velocity profile correlation. A CWUD measuring system was built to emit an ultrasonic wave of 1MHz and collect the frequency shift of the reflected waves. Dynamic experiments were carried out in a horizontal pipe of inner diameter of 50mm with the CWUD system. Six flow patterns of horizontal oil–water two-phase flow were observed including both the water continuous flow and the oil continuous flow. According to the results, the average frequency shift in oil–water two-phase flow varies with the flow pattern. The flow velocity correlations are separately established for the oil continuous dispersed flow, water continuous dispersed flow and stratified flow, based on the analysis of flow velocity profile correction. The average relative error of the overall superficial velocity is 3.63% with a maximum relative error of 12.22%.

Turbulent forced convection effectiveness of alumina–water nanofluid in a circular tube with elevated inlet fluid temperatures: An experimental study

The present study aims to explore experimentally the influence of elevated inlet fluid temperature on the turbulent forced convective heat transfer effectiveness of using alumina–water nanofluid over pure water in an iso-flux heated horizontal circular tube at a fixed heating power. A copper circular pipe of inner diameter 3.4mm was used in the forced convection experiments undertaken for the pertinent parameters in the following ranges: the inlet fluid temperature, Tin=25°C, 37°C and 50°C; the Reynolds number, Rebf=3000–13,000; the mass fraction of the alumina nanoparticles in the water-based nanofluid formulated, ωnp=0, 2, 5, and 10wt.%; and the heating flux, qo″=57.8–63.1kW/m2. The experimental results clearly indicate that the turbulent forced convection heat transfer effectiveness of the alumina–water nanofluid over that of the pure water can be further uplifted by elevating its inlet temperature entering the circular tube well above the ambient, thereby manifesting its potential as an effective warm functional coolant. Specifically, an increase in the averaged heat transfer enhancement of more than 44% arises for the nanofluid of ωnp=2wt.% as the inlet fluid temperature is increased from 25°C to 50°C.

Laminar flow control via utilization of pipe entrance inserts (a comment on entrance length concept)

Flow field measurements behind pipe entrance inserts called as flow conditioners in a mean flow Reynolds number range 547 ≤ Re ≤ 9000 are presented herein. A tube bundle, a Laws’ perforated plate and an etoile were located at the entrance of a smooth circular pipe of inner diameter, D = 26.6 mm . The covered ranges of open area ratio, β and non-dimensional length, L / D were 0.49 ≤ β ≤ 0.74 and 0.123 ≤ L / D ≤ 2 respectively. The cross-sectional axial velocity u = u ( r ) profiles at the downstream stations of X / D = 75 , X / D = 375 , X / D = 680 together with pressure losses Δ P are referred to determine the influence of utilized designs. The flow conditioners have a single performance characteristic expressed through a relationship of pressure loss coefficient K = K ( Re β ) which provides a practical method for the calculation of time-averaged pressure loss, Δ P ̄ in an average error margin of ±18%. The laminar flow inside the pipe without an insert in the range of Re < 2450 is not fully developed sensed with u = u ( r ) profiles having a ±20% deviation from the Blasius profile for the lengths X / D < 680 . Meanwhile flow conditioners provide a fully developed laminar flow independent of Re and X observed in terms of downstream u = u ( r ) profiles with a better fit to the Blasius profile in a mean error margin of ±10%. The laminar flow control via flow conditioners is analyzed through a discussion in terms of the introduced local non-dimensional velocity parameters. The used methodology is based on the definition of entrance length Reynolds Number; Re X = ( X / D ) Re . The proposed equations “ Re X β = C ” (where C is a constant) can be used for the estimation of settling distance of the flow conditioners and laminar entrance length. The experimental data are in conformity with the magnitudes of C = 2.87 × 10 4 and C = 3 × 10 5 with the corresponding error margins of ±4% and ±6% respectively.

Solids Transport Formula in Predictive Model for Pipe Flow of Slurry above Deposit

Recently, principles of a predictive model were proposed for pipe flows of settling slurries at low velocities for which a plane stationary bed is formed at the bottom of the pressurized pipe. The solids transport formula is an important component of the model. An analysis of experiments for 11 different solids fractions suggested that the transport formula of the MPM (Meyer-Peter and Müller) type is appropriate for relating the solids discharge with the flow conditions in a pipe provided that the empirical coefficients of the MPM equation are not considered constant. The structure of the transport formula is discussed and its validity tested in the light of the new experimental results. Recent experiments in the laboratory circuit with a pipe of inner diameter of 100 mm were carried out for three different fractions of sand (median particle sizes of 0.22 mm, 0.38 mm, 1.36 mm, respectively). Slurry flows were tested in the upper-plane bed regime within the range of velocities from 0.19 to 1.97 m/s and delivered concentrations from virtually zero to 0.27. The tests confirmed that the formula holds well from relatively fine to very coarse settling slurries flowing above eroded deposit in pressurized pipes.

Development of Impurity Influx Monitor (Divertor) for ITER

The optical design of Impurity Influx Monitor (divertor) was carried out for new ITER design and ray-tracing analysis shows that the spatial resolution of ITER requirement (50 mm) will be achieved by these optical systems designed here. The mechanical design of front end optics also carried out based on the optical design and results of port integration. In the upper port, front end optics can be installed inside the pipe of inner diameter of φ300 mm. In the equatorial port, all the optical component are placed to avoid the interaction with other diagnostic equipments. Heat analysis was carried out for the optimization the cooling method of mirrors, mirror holders and mounting modules to reduce the temperature rise caused by the nuclear heating. It indicates that mirrors can be cooled by the thermal conduction using mirror holders made of a copper alloy and making many cooling channels on the mounting module. Finally, the effect of the thermal deformation to the optical properties is estimated by using the optical design code.

インターレーサ内の非圧縮性空気流れの特性

The present study is concerned with numerical simulation of air flow in a yarn duct of an interlacer, which is an apparatus for yarn intermingling. A nozzle of circular pipe of inner diameter d(<D) is mounted perpendicularly to the yarn duct of circular pipe of inner diameter D and length L. The air is injected from the nozzle into the yarn duct. This complex incompressible air flow of the interlacer system is analyzed by a numerical calculation program, FIDAP, using the high Reynolds number k-e model. The air flow in the yarn duct can be simulated well by this analysis for d/D≤0.5. For d/D≤0.75, however, the predicted results for air flow in the yarn duct are not in satisfactory agreement with the measurements. The effect of the value of d/D on the air flow in the yarn duct is discussed. It is clearly found that for d/D≤0.5 the circumferential air flow along the inner wall of the yarn duct is dominant, while for d/D≥0.75 the axial air flow is dominant. The interlacer with 0.5≥d/D≤0.7 is usually used in the practical interlacing processing, where the condition of the air flow largely changes from circumferential to axial flow. Furthermore,the ratio d/D has no great effect on the flow in the yarn duct for d/D≥7.

Measurement of Averaged Liquid Velocity Field around Large Bubbles Using UVP

An Ultrasonic Velocity Profile monitor (UVP) measurement was performed to measure the averaged liquid velocity field in front of, around and behind the large bubble rising in stagnant water in a round pipe of inner diameter D=54 mm in order to obtain fundamental information for the gas liquid two-phase slug flows. Two ultrasonic transducers were used for the measurement to get velocity vectors. The measured results are presented and compared with some existing studies on the corresponding phenomena. In the liquid film near the bubble nose, velocity profiles are presented and compared with existing studies. The different of D may affect some features. The parameter z/D is found more dominant than z for this phenomenon. In the liquid phase behind the bubble tail or the wake region, a large ring vortex is recognized. The effect of bubble length on the vortex is also discussed. The upward velocity at the pipe axis agrees well the predicted results by an existing prediction.

Measurement of Averaged Liquid Velocity Field around Large Bubbles Rising in Stagnant Water in Round Pipe Using UVP

An ultrasonic velocity profile monitor (UVP) measurement was performed to measure the average liquid velocity field around a large bubble rising in stagnant water in a round pipe of inner diameter D=54mm in order to obtain fundamental information for gas-liquid two-phase slug flows. Two ultrasonic transducers were set at different directions to obtain velocity vectors. The measured results are presented and compared with the results of some previous studies on the corresponding phenomena. In the liquid film near the bubble nose, the difference in bubble length does not affect the acceleration. The parameter z/D is more dominant than z itself, particularly when z/D is less than unity. In the wake region, a large ring vortex is recognized. The upward velocity at the pipe axis agrees well with previously predicted results. The effect of bubble length on the vortex length is also discussed.

Drag reduction and heat transfer of surfactants flowing in a capillary tube

Pressure drop and heat transfer were measured in fully developed laminar flow in a pipe of inner diameter 1.07 mm in the range of Reynolds numbers 10⩽ Re⩽450. The study was performed for water and water–surfactant solution of 530 and 1060 ppm. It was shown that these surfactant solutions increase the pressure drop in adiabatic and diabatic flows. The dependence of friction coefficients as a function of solvent Reynolds number was used to predict the ability of certain surfactant solutions to increase drag in laminar flows. The experimental values of the Nusselt number depend significantly on the thermal conduction through the tube wall. They become lower than theoretically predicted for tubes heated with constant heat flux on the wall. The heat transfer coefficients with surfactant solutions were higher than that in water flow at the same bulk velocity. The results showed that the Peclet number is an additional parameter needed for a description of the averaged Nusselt number in laminar pipe flow of water and surfactant solution.

Drag reduction and heat transfer of surfactants flowing in a capillary tube

Pressure drop and heat transfer were measured in fully developed laminar flow in a pipe of inner diameter 1.07 mm in the range of Reynolds numbers 10⩽ Re ⩽450. The study was performed for water and water–surfactant solution of 530 and 1060 ppm. It was shown that these surfactant solutions increase the pressure drop in adiabatic and diabatic flows. The dependence of friction coefficients as a function of solvent Reynolds number was used to predict the ability of certain surfactant solutions to increase drag in laminar flows. The experimental values of the Nusselt number depend significantly on the thermal conduction through the tube wall. They become lower than theoretically predicted for tubes heated with constant heat flux on the wall. The heat transfer coefficients with surfactant solutions were higher than that in water flow at the same bulk velocity. The results showed that the Peclet number is an additional parameter needed for a description of the averaged Nusselt number in laminar pipe flow of water and surfactant solution.

Oscillation and gain characteristics of high power co-axially excited N 2 gas lasers

A new type of co-axial discharge gas laser has been developed as a nitrogen laser, and the gain properties have been measured. The co-axial discharge tube consists of a ceramic pipe of inner diameter of 5 mm and length of 15 cm with two metallic electrodes at both ends. The excitation discharge was activated using a capacitor transfer circuit with a special pre-ionization discharge through the ceramic pipe. When the tube is used as an oscillator, an output laser energy of 0.45 mJ was obtained with pure N 2 gas at pressure of 933 Pa (7 Torr). The time resolved gain measurement of N 2 laser was made in the oscillator–amplifier configuration, and the value of the peak gain coefficient was estimated to 0.1 cm −1. The circuit analysis of the discharge circuit was also made to estimate discharge resistances, inductances and currents in the excitation circuit. The laser output increased up to 1.95 mJ at the charging voltage of 28 kV when the length and inner diameter of the discharge tube were increased to 30 cm and 9 mm respectively.

An experimental investigation of capsules of anomalous shape conveyed by liquid in a pipe

This paper deals with the effect of bulk fluid velocity, diameter and length ratios, apparent density and volumetric concentration on the capsule/liquid velocity ratio, pressure gradient of the capsule flow in the pipe and on the position of capsules. The position and shape deformation of semi-rigid capsules contributed to the explanation of the effect and distribution of the transversal hydrodynamic forces, acting on a capsule. Measurements were carried out in a horizontal straight plexiglass pipe of inner diameter 0.05 m and water was used as a carrier liquid. It was found that the semi-rigid capsule trains reached lower velocities than the rigid ones for the regime given by Reynolds number ( Re) lower than 5×10 4, whereas the opposite holds for the region where the Re exceeds 10 5. The semi-rigid capsule trains have about 20% lower pressure gradient than trains consisted of identical solid cylindrical capsules for the regime given by Re lower than 5×10 4, for the higher flow velocity this effect gradually disappears.

Diffusion of Matter in Wall Turbulent Flow. (4th Report. Local Similarity of Mean Concentration Field of the Plume from a Wall Point Source in Turbulent Pipe Flow).

The aim of this study is to find similar solutions of the ordinary differential equation for the suitably normalized function in order to describe the mean concentration distribution, the similarities of which were experimentally observed in the some region downstream of a wall point source plume in a turbulent pipe flow. Solutions of these equations are compared with experimental data, which were obtained in an almost fully-developed water turbulent pipe flow (ReD=20000) that has been realized in a horizontal straight pipe of inner diameter 100 mm. It is found that these solutions show good agreement with experimental data, and the widths of similar profiles are strongly affected by the curvature of the boundary of the flow field. This is mainly caused by the diffusion term in a conservation equation for the mean concentration field. Also, the ordinary differential equation for the normalized mean concentration function in the case of a wall point source plume in a turbulent boundary layer on a flat plate is found to be a special case of the corresponding equation for a turbulent pipe flow.

Diffusion of Matter in the Wall Turbulent Flow. 1st Report. Similarity of a Diffusion Plume from a Wall Point Source in a Pipe Flow.

The aim of this study is to elucidate experimentally the spatial structure and the statistical properties of the plume diffusion field of matter from a wall point source in a turbulent pipe flow. The fully developed water turbulent flow of Reynolds number 20000 has been realized in the horizontal straight pipe of inner diameter 100 mm. The concentration field downstream from a continuous point source on the wall has been measured using a reflection-type fiber optic probe (sampling volume s 6.3×10-6cc). It is found that the vertical profiles of the mean concentration and concentration fluctuation r. m. s. value at the different downstream positions from the source show self-similarity on the symmetric plane of the diffusion field. In particular, the mean concentration profile can be described quite well by the universal function which was suggested for a point or a line source plume in the turbulent boundary layer on the flat plate.

MATHEMATICAL MODELING OF THE AIR PRESSURE REDUCER OPTIMUM NOZZLE DIAMETER OF ITS TESTING PIPE

One of the most important elements in the pneumatic circuits is the pressure reducer which is commonly used to keep a constant downstream pressure, whatever the value of the upstream one. In fact the downstream pressure would anyway vary, but it could be considered to operate with a sufficient accuracy if its outlet. pressure varies within a zone of ±5% of its nominal value. That is why every pressure reducer, after being manufactured then assembled; must be tested to verify its function, and whether it works in the prescribed tolerance. The testing bench consists of several pressurized air bottles, branches to the pressure reducer, downstream of which there mounted a short pipe of inner diameter: dpipe ; nozzled at its outlet end witha diameter: dn. In the present research, a complete mathematical model is developed to find out the optimum nozzle diameter of the testing section which is necessary to identify the function of certain reducer.