Flow Pipes Research Articles

Attachment detection on the inner wall of gas-liquid two phase flow pipe based on ultrasonic guided waves

Gas-liquid two-phase flow pipelines are commonly found in building thermal systems. However, the attachment on the inner wall of the pipeline brings great safety hazards to the system. At present, ultrasonic guided wave technology has been widely used for the structural inspection of pipelines. The boundary conditions significantly affect the propagation characteristics of ultrasonic guided waves and the detection accuracy. Therefore, this paper investigates the influence of the flow pattern on the propagation characteristics of guided waves using semi-analytical finite element method and proposes an excitation frequency selection method independent of the flow pattern to improve the accuracy of the detection of attachments in gas-liquid two-phase flow pipelines. The relationship between the attachment size and the reflection echo characteristics is analyzed. Numerical simulation and experimental results show that the flow pattern leads to the modal coupling phenomenon of the L(0,1) guided wave, and the modes vary with the spatial distribution of the gas plug. The attachment echo contains not only the attachment information but also the position of the gas plug in the fluid. Finally, the maximum error of the attachment position accuracy in two-phase flow pipes with different flow patterns is no more than 3 %. An innovative dispersive surface result reflecting the changes in the propagation characteristics of UGWs along a pipe with changing cross-section (plug flow) is established.

The influence of addition maja fruit peel extract as inhibitor on the corrosion rate of stainless steel and carbon steel

Corrosion can cause serious damage, such as a piece of equipment or a decrease in tool life. The materials used in an industry, its use can be seen in factory flow pipes that carry a substance, which is one of the factors causing corrosion. The aim of this research is to determine the performance of maja rind extract as an inhibitor of stainless steel and carbon steel corrosion rates, to determine the inhibition efficiency of maja rind extract in controlling the corrosion rate of stainless steel and carbon steel. Method use in this reasearch extraction and polarization. The best concentration in controlling the corrosion rate of SS 304 was obtained at 100 ppm with a corrosion rate of 0.00963 mpy, for SS 316 it was obtained at 100 ppm with a corrosion rate of 0.00521 mpy, while on steel plate it was obtained at 100 ppm with a corrosion rate of 0.00774 mpy. The best inhibitor efficiency on SS 304 can reach 97.6% with the best concentration of 100 ppm, on SS 316 it can reach 99.4% with the best concentration of 100 ppm, and on steel plate it can reach 98.84% with the best concentration of 100 ppm.

The effect of bubble size in descaling process of bubble flow pipes based on leaky ultrasonic guided waves

Crystal scaling in gas-liquid two phase flow pipes is a common issue in many fields, such as chemical engineering, water industries, and energy industries, posing a great threat to the production process and the environment. The characters of air bubbles in the bubble flow have a serious impact on the ultrasonic guided wave descaling inside a pipe. The interaction mechanism between the air bubbles with various sizes and the cavitation bubbles are studied in this paper by combined the finite element method and the bubble dynamics equation, qualitatively analyzing the impact of the air bubble size and the acoustic pressure in the fluid field on the leaky ultrasonic guided waves descaling. The numerical and experiment results show that the maximum expansion radius ratio of cavitation bubble is suppressed from 2.4 to 1.3 when the radius of air bubble grows from 0.5 mm to 4.5 mm. The Ca content removal ratio at 35.5 cm was 81 %, 66 % and 28 %, while the Ca content removal ratio at 60 cm was 76 %, 56 % and 16 % when the gas outlet orifice is 100 μm, 200 μm and 300 μm respectively in the experiment. The results indicate that large bubbles in two phase flow inhibit the cavitation effect of cavitation bubbles and reduce the effectiveness of descaling.

Seismic architecture of Yongle isolated carbonate platform in Xisha Archipelago, South China Sea

This study presented recently reprocessed multi-channel seismic data and multi-beam bathymetric map to reveal the geomorphology and stratigraphic architecture of the Yongle isolated carbonate platform in the Xisha Archipelago, northwestern South China Sea. Our results show that the upper slope angles of Yongle carbonate platform exceed 10° and even reach to ∼32.5° whereas the lower slope angles vary from .5° to 5.3°. The variations of slope angles show that margins of Yongle Atoll belong to escarpment (bypass) margins to erosional (escarpment) margins. The interior of carbonate platform is characterized by sub-parallel to parallel, semi-continuous to continuous reflectors with medium-to high-amplitude and low-to medium-frequency. The platform shows a sub-flat to flat-topped shape in its geometry with aggradation and backstepping occurring on the platform margins. According to our seismic-well correlation, the isolated carbonate platform started forming in Early Miocene, grew during Early to Middle Miocene, and subsequently underwent drowning in Late Miocene, Pliocene and Quaternary. Large-scale submarine mass transport deposits are observed in the southeastern and southern slopes of Yongle Atoll to reshape the slopes since Late Miocene. The magmatism and hydrothermal fluid flow pipes around the Yongle Atoll have been active during 10.5–2.6 Ma. Their activity might intensify dolomitization of the Xisha isolated carbonate platforms during Late Miocene to Pliocene. Our results further suggest that the Yongle carbonate platform is situated upon a pre-existing fault-bounded block with a flat pre-Cenozoic basement rather than a large scale volcano as previously known and the depth of the basement likely reached to 1400 m, which is deeper than the well CK-2 suggested.

Numerical Investigation of Particle Focusing Patterns in Laminar Pipe Flow With High Reynolds Numbers

The inertial focusing characteristics of particles in laminar flow pipes with high <i>Re</i> numbers were studied based on the “relative motion model”. In order to solve the problem of long pipes with high <i>Re</i> number flow, periodic boundary conditions were imposed on the inlet and outlet of the pipe. The research results show that the use of periodic boundary conditions can effectively reduce the computational, and the mechanical properties of particles in high <i>Re</i> flow can be calculated by using <i>L</i>=4<i>D</i> pipe. The difference from the low <i>Re</i> number is that as the <i>Re</i> number continues to increase,the lift force of the particles in the radial direction is no longer distributed as a parabola. The lift curve has a concave area between <i>r</i>⁺ =0.5 ~ 0.7, and there is a tendency for a new inertial focus point to appear in this section. By means of particles of <i>a</i>⁺ =1/17 for <i>Re</i> &gt; 1 000, this new focus point position is solvable. In addition, in the analysis of the flow field, a secondary flow occurs around the particle, and its intensity gradually increases with the <i>Re</i> number and the closeness of the particle to the wall. The generation of the secondary flow affects the spatial distribution of the particle lift.

Stability of human stress hormones and stress hormone metabolites in wastewater under oxic and anoxic conditions.

Levels in wastewater of human stress biomarkers, such as cortisone (E), cortisol (F), tetrahydrocortisone (THE), and tetrahydrocortisol (THF) may serve as indicators of population wellbeing and overall health. This study examined the stability of these biosignature compounds in wastewater to inform on their applicability for use in wastewater-based epidemiology (WBE). Wastewater from two undisclosed U.S. municipalities were fortified with the above four biomarkers of stress to a concentration of 10 ppb, and their decay was studied at three temperatures (15, 25, and 35 °C) over 24 h in oxic and anoxic conditions. Samples were analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS) in conjunction with the isotope dilution method for absolute quantitation. Results demonstrated short-term persistence (24 h) of biomarkers at low temperatures (15 °C), and accelerating kinetics of decay that were positively correlated with temperature increases. Among the four biomarkers evaluated, the tetrahydro derivatives were the most long-lived sewage-borne stress biomarkers and these are recommended as prime analytical targets for use in WBE when tracking population stress. Statistical analyses using a non-parametric Wilcoxon test further revealed no significant differences (p > 0.05) between oxic and anoxic decay rates for all stress biomarkers in wastewater from all study locations, regardless of the prevailing temperature regime. This negative finding is worthy of reporting because it suggests the feasibility of straightforward modeling of stress hormone decay, irrespective of whether the sewerage system monitored contains fully filled, pressurized pipes or partially filled gravity flow pipes, whose filling level, and with it its redox conditions, are known to fluctuate over time with water use and storm events.

A Semi-empirical correlation for stratified two-phase flow friction factors

The optimal design of two-phase flow pipes depends on various variables. Pressure drop and liquid hold-up are essential parameters in the appropriate design of pipes. These parameters can be estimated by numerical simulation of pipes. However, the simulation strongly depends on both phase frictions. Frictions are commonly calculated using friction factors, and various empirical correlations have been proposed to calculate friction factors, but most of these correlations are dependent on the experimental conditions.The present study proposes a semi-empirical friction factor model by modifying an existing model in the literature for stratified two-phase flows. Experimental data from various laboratories are taken to validate the interface shear stress, velocity profile and pressure gradient. Compared with previous models, the predicted velocity profiles and shear stresses are in better agreement with the experimental data.

Development of adjustable fluid damper device for the bridges subjected to traffic loads

In this research, an Adjustable Bypass Fluid Damper (ABFD) is developed by utilizing a pair of external fluid flow pipes and flow control valves. The flow control valves control the flow pressure of the fluid passing through bypass pipes and adjusted the function of the fluid damper to limit the displacement of the structure within the allowable range. Therefore, the function of the fluid damper device is adjustable according to the displacement of the structure.The ABFD device is developed through implementing an adjustable valve in bypass pipes that able to change and adjust the flow and pressure of the oil inside the viscous damper during movement of piston under applied vibrations and control the resultant damping and resistance force of the damper device. Therefore, through the new proposed design, the action of viscous damper has been changed from passive control device to an adjustable system which is capable to function as an device with different capacities and also able to change the response from a damping device to a restrainer system. The analytical model of the proposed ABFD device is developed and the performance of the device has been formulated according to the control valve position. Then the finite volume model of the moving fluid inside the device has been developed and the function of the device was evaluated through Computational Fluid Dynamics analysis.In the next step, the prototype of ABFD has been fabricated and experimental tests have been conducted using a dynamic actuator to evaluate the performance of the device in various control valve conditions.The numerical analysis and experimental test results for the ABFD prototype revealed that the developed device is capable of developing a wide range of damping levels and there is a desirable agreement between numerical predictions and experimental results.Thereafter, to examine the effect of the application of the ABFD device in the bridge structures, the proposed ABFD device was implemented in the 19/5 California overcrossing bridge. The considered bridge equipped with an ABFD device is modeled using the finite element method and it’s subjected to the passing vehicle loadings. The results showed that the bridge's response is dramatically improved with the implementation of the six ABFD dampers and the peak displacement of the structure reduces by 35 percent while the control valves are half-open.

The heterogeneity of the hydromorphological responses of a stream to the urbanization of its basin

AbstractMorphological adjustment mechanisms and controls of small urban rivers are rarely studied especially in France. We propose an original hydrogeomorphological approach based on a detailed study of a whole catchment using field data acquired systematically all along the river: (i) channel cross‐sections; (ii) riffle‐pool sequences and (iii) obstacles to flow and rainwater drainage pipes. The entire length of the river was surveyed and the channel geometry (depth and width at bankfull) was measured on a cross‐section every 180 m or at each riffle (depending on which of the two intervals happened to be the shortest). The 357 transects thus established constitute as many elementary units of measurement (EUM) of the hydrographic network. Nine hydromorphological variables were used as a basis to classify the profiles (principal component analysis/hierarchical clustering analysis). The types were compared with 12 anthropogenic constraining variables to explain longitudinal morphological variability and to link morphology to pressures on this scale. The results showed an average incision of 0.50 m (locally over 1 m), an average widening of nearly 1 m (locally over 3 m), and heterogeneous distribution of the riffle‐pool sequences (although not complete disappearance). Systematic analysis of within‐channel forms revealed high morphological diversity, the absence of a linear relationship between the rate of urbanization and incision/erosion, and the absence of longitudinal changes in response to urbanization. The constraints identified are commonly observed in urbanized basins, but the variety of responses to the constraints makes it difficult to understand the system as a whole and prevents uniform ecological restoration along the entire river.

Teknologi Pirolisis Pembuatan Asap Cair dari Sekam Padi

The production and use of liquid smoke from rice husks among the farming community in Belitang sub-district is still very limited and not many people even know about liquid smoke and its benefits. During the rice husk is made of charcoal and used for mixing the soil as an additional nutrient to the soil. Seeing these conditions, the aim of carrying out community service activities is to increase public knowledge of the potential of rice husk in the form of liquid smoke which can be used as an organic pesticide. The activity method is carried out in several steps, namely socialization, the process of making and assembling tools and the practice of making smoke by the community on a small scale. Designed pyrolysator equipment portable consisting of combustion chamber tubes, smoke cooling chamber tubes and smoke flow pipes which are used to produce liquid smoke. The rice husk burning process was carried out using a pyrolysis scheme within 6 hours and produced 90 ml of black liquid smoke with little oil content. This indicates that the liquid smoke produced is of low quality. The result of this Community Service Program (PPM) activity is that the community understands and understands the use of liquid smoke and the process of making liquid smoke.

Numerical study on heat transfer efficiency for borehole heat exchangers in Linqu County, Shandong Province, China

Developing shallow geothermal energy with borehole heat exchangers helps energy supply and CO2 emission reduction. This paper comprehensively investigates the influencing factors on heat transfer efficiency of a single borehole heat exchanger based on the field investigations in Linqu County, Shandong Province, China. We built a three-dimensional numerical model validated by a thermal response test. We systemically investigated the influence of groundwater seepage, circulating water flow rate, pipes spacing and length, the operation interval, and the annual operation mode on the heat transfer efficiency. The results show that the heat transfer efficiency decreases with long-term operation due to surrounding soil’s cold/heat accumulation. The groundwater seepage increases the heat transfer efficiency. The heat transfer efficiency increases with the pipe length, inlet and outlet pipes spacing, and operation interval. It decreases with the circulating water flow rate. The annual operation mode is of greatest importance in the heat transfer efficiency among the studied influencing factors. Compared to working only in winter, the average heat transfer efficiency coefficient increased by 0.152 when working in winter and summer. The results provide a reference for the practical installation and optimization of the borehole heat exchanger for sustainable utilization of shallow geothermal energy.

Prompt gamma-ray methods for industrial process evaluation: A simulation study

Abstract Radioisotope applications in industrial process inspection and evaluation using gamma-ray emitters provide otherwise unavailable information. Offering alternative gamma-ray sources can support the technology by complementing sources’ availability and radiation safety. This work proposes to replace gamma-ray from radioisotopes with prompt gamma-ray from the interaction of neutrons with stable isotopes injected into the industrial process or with the structural material of the industrial process equipment. Monte Carlo N-Particle Transport Code (MCNP5) was used to simulate the irradiation of two-phase flow pipes by 252Cf neutron source. Two simulations were run for each pipe, with and without mixing the liquid phase with the stable isotope 157Gd. The detected gamma-ray spectra were analysed, and images of the two phases inside the pipes were produced. The images were compared to images obtained from simulations of gamma transmission measurement using 60Co. Furthermore, results for prompt gamma computed tomography (CT) were presented and discussed. The studies’ outcomes indicate the potential of prompt gamma-ray to carry out the sealed sources applications of gamma transmission measurements and imaging.

Development of a PCM-HE to harness waste greywater heat: A case study of a residential building

Waste greywater (GW) from non-industrial buildings has considerable exergy that must be exploited for a sustainable future. Scavenging this low-grade heat from GW into cold water (CW) before storage in a phase change material (PCM) is a novel approach to decouple demand and supply along with integrating storage and transfer in a single heat exchanger (HE). A methodology to optimally select an appropriate PCM along with the heat transfer enhancement procedures both internal and external to the flow pipes is presented. This procedure can be extended to reduce the hot water heating demand for applications in both residential and larger commercial buildings. Furthermore, a design technique to numerically assess the performance of a full-scale HE based on empirical formulations of a unit-volume are also put forward. As a case study, the performance of a counter-flow PCM-HE with vertically cascaded GW and CW finned-corrugated pipes is assessed for heat recovery in household appliances of a residential building. Such HE with 9 m piping length can increment the incoming CW temperature by 9.5 K with complete phase change of 30 kg of PCM in 900 s. A transfer of about 5,100 kJ of heat for PCM melting with GW outflow and freezing with CW inflow occurs within this time frame. Furthermore, to fully exploit the temperature differences between the fluids a three-cascaded PCM arrangement enhances the CW outlet temperature by 64%. The installation of this PCM-HE in a four-member UK household, can save 4,687 kWh of energy annually with a payback time of 4.44 years.

Numerical analysis of heat transfer enhancement in pulsating flow pipes

In this paper, a rectangular flow runner is used as the research object to study the influence of adding a spoiler on the wall of the flow runner on its heat transfer characteristics and flow characteristics. Using the finite element method to analyse the influence of different spoiler’s structures and parameters of the spoilers on the heat transfer characteristics and flow characteristics of the flow runner, the study found that: by the comparison of the smooth flow runner and the rectangular spoiler flow runner, the comprehensive heat exchange effect of the spoiler runner is the best when the arc is arranged in the flow runner, and the accumulation effect of impurities in the runner is the slowest.

3D Numerical Simulation and Performance Analysis of CO2 Vortex Tubes

In view of the extensive application of swirl flow pipes (vortex tubes) in refrigeration systems, the parameters of swirl flow pipes were investigated to provide optimal cooling and heating conditions. Three-dimensional numerical simulations were carried out using available experimental data and models. The analysis verified that the heat pipe with a length of 175 mm performed better than the swirl flow pipe with a length of 125 mm, confirming experiments by Agrawal. Meanwhile, by comparing different pressures, it was found that in the single-nozzle swirl flow pipe, the greater the increase of pressure (0.1–1.0 MPa), the greater the burden on the vortex chamber and the more serious the wear is, which can be seen in the higher inlet pressure. In order to improve the durability of the swirl flow pipe, we suggest using a swirl flow pipe with more nozzles. Finally, according to the simulation results, with the rise of carbon dioxide pressure potential energy at the inlet, the cooling effect of the swirl flow is first increasing and then decreasing. When the swirl flow pipe is used as a refrigeration device to determine the minimum cooling temperature under the maximum pressure, the lowest temperature of the 125 mm swirl flow pipe was 252.4 K at 0.8 MPa, while the lowest temperature of the 175 mm swirl flow pipe was 246.0 K. Secondly, the distance from the inlet to the hot outlet of the swirl flow pipe had little effect on the cooling temperature and radial velocity, but increasing its distance increased the wall temperature of the swirl flow pipe because it increases the contact time between the airflow and the hot end of the tube wall. When the swirl flow pipe is used as a heat-producing device, increasing the tube length of the swirl flow pipe appropriately increases its maximum heat-producing temperature.

Energy and Economic Analysis of Curved, Straight, and Spiral Flow Flat-Plate Solar Water Collector

In this work, the solar water collector flow tube geometry is modified as curved and spiral to enhance the system’s performance. The investigation is carried out experimentally under the meteorological conditions of the Kovilpatti region (9°10 ′ 0 ″ N, 77°52 ′ 0 ″ E), Tamil Nadu, India. The flow pipes of the solar water heater are made of copper material which has higher thermal conductivity to recover the water heat as thermal energy. The influence of the mass flow rate (MF) on the flow pipes with respect to the surface temperature for various configurations of the flow tubes is investigated. The two MFs of 0.0045 kg/s and 0.006 kg/s are tested. The MF of 0.006 kg/s yields the maximum efficiency of 73% compared to the other MF. The straight, curved, and spiral tubes yielded the maximum efficiency of 58%, 62%, and 69%, respectively, at 0.0045 kg/s. Similarly, the MF of 0.006 kg/s obtained an efficiency of 62%, 65%, and 73% for straight, curved, and spiral flow tubes, respectively. The economics and exergy of the system are analyzed. The maximum exergy efficiency of the collector is estimated to be 32% for the MF of 0.0045 kg/s for the spiral flow collector, and for the 0.006 kg/s MF, the obtained exergy efficiency is 27% for the spiral flow water heater. The economic analysis revealed that the expense is $0.0608 and $0.0512 worth of hot water produced for the domestic space heating.

Performance analysis of hydrogen fuel cell with two-stage turbo compressor for automotive applications

This paper discusses the numerical modeling of an automobile fuel cell system using a two-stage turbo-compressor for air supply. The numerical model incorporates essential input parameters for air and hydrogen flow. The model also performed mass and energy balances across different components such as pump, fan, heat-exchanger, air compressor and keeps in consideration the pressure losses across flow pipes and various mechanical parts. The compressor design process initiates with numerical analysis of the preliminary design of a highly efficient two-stage turbo compressor with an expander, as a single-stage compressor has several limitations in terms of efficiency and pressure ratio. The compressor’s design parameters were carefully studied and analyzed with respect to the highly efficient fuel cell stack (FCS) used in modern hydrogen vehicles. The model is solved to evaluate the overall performance of PEM FCS. The final compressor has a total pressure and temperature of 4.2 bar and 149.3°C, whereas the required power is 20.08kW with 3.18kW power losses and having a combined efficiency of 70.8%. According to the FC model with and without expander, the net-power outputs are 98.15kW and 88.27kW, respectively, and the maximum efficiencies are 65.1% and 59.1%, respectively. Therefore, it can be concluded that a two-stage turbo compressor with a turbo-expander can have significant effects on overall system power and efficiency. The model can be used to predict and optimize system performance for PEM FCS at different operating conditions.

Fuel Cell designing with optimal high speed air compressor

This paper discusses different air management technologies for fuel cell systems. Two different types of compressors are analyzed for Proton-exchange membrane fuel cells (PEMFC). Some important criteria are analyzed thoroughly for the selection of turbo compressor among different types of compressors illustrated with the help of matrix representations. The impacts of various input parameters for Fuel Cell (FC) are also explained thoroughly. Later the numerical modeling of an automobile fuel cell system using a high speed turbo-compressor for air supply is explained. The numerical model incorporates the important input parameters related with air and hydrogen. It also performed energy and mass balances across different components such as pump, fan, heat-exchanger, air compressor and also keeps in consideration the pressure drop across the flow pipes and various mechanical parts. The model is solved to obtain the characteristics of the FC system at different operating conditions. Therefore, it can be concluded that the high speed turbo compressor with a turbo-expander can have significant effects on the overall system power and efficiency.

Numerical Simulation of the Hydrodynamics and Mass Transfer in the Cuboid KDP Crystal Growth under the Jet‐Rotating Crystal Method

AbstractA novel method of crystal growth by introducing jet flow to the pyramidal‐restriction long‐seed growth system of potassium dihydrogen phosphate (KH2PO4, KDP) in rotating crystal method, namely, the jet‐rotating crystal method, is proposed. To evaluate the prospect of this new method, three‐dimensional (3D) time‐dependent numerical simulations of flow and mass transfer involved in the jet‐rotating crystal method are conducted. Compared with the rotating crystal method, the jet‐rotating crystal method can improve the magnitude and distribution homogeneity of the prismatic face supersaturation and obtain high‐quality KDP crystals. The supersaturation on the prismatic face as a function of rotation rate, jet velocity, and crystal size is investigated. The effects of solution flow on mass transfer are analyzed in detail. A further improvement in the magnitude and distribution homogeneity of the prismatic face supersaturation can be observed through designing the jet flow pipes to swing periodically in vertical plane. Besides, the role of natural and forced convection in mass transport is discussed, which indicates that the effects of natural convection can be neglected when the jet velocity is equal to or greater than 0.6 m s–1.

Effect of velocity and water cut on water distribution in elbows of petroleum pipelines

As one of the main energy sources, petroleum and natural gas are widely used around the world. Safety of the transportation causes more attentions recently. Currently, since some oil wells are in the late period of the production, water pre-injection is often used to rise the well pressure. Thus, the water cut is usually high in oil gathering pipelines. The inner wall of pipelines without coating would be corroded by contacting with the mixed corrosive medium and water during the long-term running, which may even lead to leakage accidents. Researches about flow pattern of oil-water multiphase flow pipes are mainly about straight pipelines, but few about elbows. In this work, water distributions in elbows of gathering pipelines were studied according to the experimental results and computational fluid dynamics (CFD) simulation results. The water deposited when the fluid velocity was low enough and the water cut is high. According to the simulation results and experimental results, an oil-water phase inversion curve was obtained to be guidance for water distribution analysis in elbows.