Increasing Pipe Diameter Research Articles

Research on Filling Strategy of Pipeline Multi-Layer Welding for Compound Narrow Gap Groove.

With the increase in transmission pressure and pipe diameter of long-distance oil and gas pipelines, automatic welding of the pipeline has become the mainstream welding method. The multi-layer and multi-pass welding path planning of large-diameter pipelines with typical narrow gap grooves are studied, and a welding strategy for pipeline external welding robot is proposed. By analyzing the shape of the weld bead section of the narrow gap groove and comparing the advantages and disadvantages of the equal-height method and the equal-area method, the mathematical model of the filling layer is established. Through the test and analysis in the workshop, the predicted lifting value meets the actual welding requirements. The microstructure of the weld was analyzed by SEM. The main structure of the weld was fine acicular ferrite, which could improve the mechanical properties of the welded joint. After multi-layer filling, the filling layer is flush with the edge of the groove. The establishment of this model lays a foundation for the formulation of welding process parameters for large-diameter pipes and the off-line programming of welding procedures.

1-G experimental study of the collapse effects on buried steel gas pipelines

Collapse disasters are commonly occurring geological disasters around buried gas pipelines and severely threaten the safety of pipeline operations. In this study, to investigate the soil deformation characteristics and mechanical response law of the pipeline under collapse, an experimental box (6 m × 1 m × 1.2 m) was built, and 1-G collapse experiments with different pipe diameters and burial depths were performed. The soil deformation laws, change in earth pressure around the pipeline, and mechanical response of the pipeline during the expansion of the collapse range were obtained by comparing and analysing the experimental results. Pipeline collapse disasters can be divided into two stages: before and after large-scale collapse disasters. The burial depth has an influence on pipeline collapse disasters mainly in a small-scale collapse range. As the collapse range increases, the influence of the burial depth on the strain distribution of the pipeline gradually decreases. However, an increase in pipe diameter can lead to a significant increase in the large-scale collapse range. Large-diameter pipelines bear greater strain than small-diameter pipelines after a large-scale collapse. This study provides data support for further research and serves as a valuable reference for pipeline safety evaluation in collapse disasters.

Numerical study on structure optimization and heat transfer characteristic of distributed pulsating flow heat exchanger

ABSTRACT Distributed pulsating flow planar tube bundle heat exchanger (DPFPTB-HE) can improve heat transfer and have a high prospect of application in the industry. Computational fluid dynamics (CFD) software Fluent was utilized as an analysis tool, and the factors affecting heat transfer in heat exchangers were comprehensively studied based on the theory of fluid mechanics and heat transfer in this article. The local average surface Nusselt number(Nu v) evaluated the heat transfer performance. Results found that the DPFPTB-HE proposed in this paper has more uniform distribution of cold fluid in the shell domain and higher heat transfer efficiency in each layer of the tube bundle compared with the conventional planar tube bundle heat exchanger (PTB-HE). In this paper’s single-factor analysis experimental session, the study showed that with the inlet velocity increases, Nu v increases; as the length of the branch pipe increases, Nu v decreases; branch pipe diameter increases, Nu v decreases. The results obtained Nu v by applying the optimal experimental parameters selected by the Taguchi method were 7.22% larger than the maximum value in the control group. The numerical result and methodology are beneficial for providing further insight into guiding the optimization of heat exchanger structure and promoting industrial progress.

Investigation of the effects of pipe diameter of internal multiphase flow on pipe elbow vibration and resonance

Computational fluid dynamics modelling of internal two-phase flow induced transient forces at 90° elbows have been carried out to evaluate the effect of pipe diameter on the characteristics of multiphase flow induced vibration. Simulations of two-phase flows of slug, cap bubbly and churn induced vibration at a pipe elbow were carried out using the volume of fluid model for the two-phase flows and the k – ε model for turbulence. Modal analysis has been carried out to evaluate the risk of resonance. Results were compared across three geometrically similar pipes of different diameters. Simulation results showed that the behaviours of the flow induced forces at the pipe elbow as a function of gas velocity for internal diameters of 0.0525 and 0.2032 m are similar. However, the multiphase flow induced force characteristics are different in the 0.1016 m diameter (intermediate) pipe. It can be attributed to the transition behaviour of gas–liquid two-phase flows caused by Taylor instability in an intermediate sized pipe. The predicted root-mean-square flow induced forces as a function of Weber number were correlated with an existing empirical correlation for a wider range of pipe sizes and gas volume fractions between 40% and 80%. Furthermore, the pipe natural frequencies increase with the increase of gas volume fraction in smaller pipes and the resonance risk increases with the increase of pipe diameter.

Removal of hydrodynamic lesions of a heated floor with a solar collector

This paper presents the results of an experimental study of the hydrodynamic process of a solar collector water-heated floor system. The water-heated floor system is designed to heat living rooms. Based on the analysis of the structures of the hot water floor, methods of their installation and the methodology of hydrodynamic calculation of the hot floor, experimental studies were conducted on the total pressure loss in the pipes of the hot water floor and the pump power used to transfer hot water from the pipes. Experimental studies were carried out in laminar and turbulent flow regimes at different diameters and different positioning steps of the water-heated floor pipe. The results of the hydrodynamic process study showed that the pressure drop and pump power were the highest at the pipe diameter and pipe pitch of 12 mm and 100 mm, i.e. 8 kPa and 18.5 W in the laminar mode and 14 kPa and 210 W in the turbulent mode. . Results obtained as the pressure loss and the power consumption of the pump decrease with increasing pipe diameter and positioning pitch ΔP = f(Re) and N = f(Re) presented in the form of a dependency graph.

Economic thickness and life cycle cost analysis of insulating layer for the urban district steam heating pipe

The direct buried steam pipeline with effective insulation has great potential application in the district heating systems. In this study, a life cycle cost model for the direct buried steam pipeline was established, and an optimization method was proposed to improve the insulation performance. The influences of insulation material and pipe diameter on the total life cycle cost, economic thickness, energy efficiency, and payback period were analyzed. Under the low-temperature working conditions, the composite insulation scheme composed of high-temperature resistant glass wool (HTRGW) and SiO2 aerogel blanket (SAB) exhibited excellent economic efficiency. Moreover, the life cycle cost and economic thickness show a significant decrease with the increase of pipe diameter, and the economic benefit increased appropriately. When the pipe diameter increased from DN100 to DN700, the life cycle cost was decreased by 351 RMB/m, the economic thickness was decreased by 71 mm, and the economic benefit was increased by 30 RMB/m. Under the high-temperature working conditions, aluminium silicate wool (ASW) was involved in the insulation scheme. When the HTRGW/SAB was adopted instead of HTRGW/ASW, the total life cycle cost was reduced by 133–224 RMB/m, the economic thickness was reduced by 52–55 mm, and the economic efficiency was increased by 17–22 RMB/(m·a).

Numerical Study on Pipeline Pressure Surge of the Large Aircraft Fuel System

The sudden closure of the refueling valve during the refueling process will cause the water hammer phenomenon in the pipeline of the large aircraft fuel system and produce pressure waves propagating along the pipeline. In serious cases, it will cause severe damage to the pipeline. The pressure surge in the pipeline can be affected by many design factors. In this study, the numerical modeling method of the large aircraft fuel system is studied using the Flowmaster program, and the accuracy of steady and transient state analysis of the simulation method is verified by experimental data. Based on this numerical method, a complete system-level simulation model of the large aircraft fuel system was established. Using this model, the effects of valve closure speed, diameter of the refueling main pipe, and refueling volume flow rate on pipeline pressure surge during the refueling process are investigated. The results indicate that all three factors have a significant impact on the pipeline pressure surge of the fuel system. The effect of the valve closing speed and the pipe diameter on the pressure surge of the pipeline is nonlinear and gradually weakened with the decrease of valve speed and the increase of pipe diameter, while the effect of refueling volume flow rate on the pipeline pressure surge is approximately linear.

Corona Characteristics of a Large-Sized AC Grading Ring and Prediction of Corona Onset Field Intensity

In order to ensure that corona discharge does not occur in the grading ring under normal operation, this paper studies corona characteristics of large-sized AC grading rings and a prediction method for corona onset field intensity (COI). First of all, a three-dimensional (3-D) finite element simulation model of the electrostatic field is established for the grading ring area where corona discharge is relatively serious in a typical EHV AC substation. The distribution law for electric field intensity of saddle-type and elliptical (circular) grading rings is calculated and analyzed, from which the result shows that pipe diameter is the main factor affecting the maximum electric field intensity (MEI) of grading rings with different structures; with continuous increase in pipe diameter, the MEI of grading rings tends to be saturated gradually. In addition, the COI tests of grading rings are carried out and test results are compared with calculation results obtained based on the Peek formula, which shows that the Peek formula has a large error in predicting the COI of a grading ring. Finally, based on test results of the COI, a formula for predicting the COI of an AC grading ring in a plain area with an altitude of 100 m is proposed by considering the effect of both the pipe diameter and the ring diameter.

Simulation of Hydrate Particle Deposition in Horizontal Annular Mist Flow

Summary In the prediction of hydrate deposition, few studies have considered the hydrate particles generated from droplets in the gas core, which makes it difficult to calculate the hydrate particle deposition accurately. Previous studies have introduced the effective deposition ratio (EDR) to predict the hydrate particle deposition from the gas core quantitatively, which simplifies the prediction process. However, a quantitative description of the EDR has not been studied. The current work has established a prediction model of hydrate particle deposition on a pipe wall and developed a method for solving the EDR based on the force analysis and removal mechanism (lifting, rolling, or slipping) of hydrate particles on the horizontal pipe wall in annular mist flow. The effects of gas velocity, pipe diameter, particle size, and other factors on the EDR of hydrate particles were analyzed using the optimized discrete particle model (DPM) in Fluent. The results show that the EDR is inversely proportional to the gas velocity under the comprehensive impacts of the turbulent kinetic energy and gas shear force. Under the influence of the liquid film "wrapping," the EDR rapidly grows and then stabilizes with the increase in particle size. Under the joint influence of the liquid film distribution and forces acting on the particles, the EDR first rapidly declines and then grows with the increase in pipe diameter, and finally tends to be stable. Through regression fitting of more than 700 sets of data, the empirical expression of the EDR of hydrate particles was established for the first time, and the error was within the allowable range in engineering. This work lays a foundation for the accurate calculation of hydrate particle deposition generated from droplets in a gas core.

EVALUATION OF THE BOTTOM SURFACE WATER JET IMPINGEMENT COOLING RATE USING MODIFIED RUN-OUT TABLE

Evaluation of Temperature-Time Profiles by the Lumped Thermal Mass analysis method for bottom surface jet impingement cooling system was carried out. This was done by controlled accelerated cooling using a modified run-out table (ROT). The evaluation was with variant pipe diameters of 10mm - 40mm by a single water jet, having impingement gaps in the range of 55mm - 95mm and controlled sub-cooled to a range of 150oC – 110oC. The results revealed that the cooling rate was faster at an impingement gap of 95mm in all the pipe diameters. This was evident from the plot of temperature-time, with a gap of 95mm showing 1.93oC/s and 3.24oC/s at diameters of 10mm and 40mm respectively. This evidently revealed that at any given pipe diameter the cooling rate is higher at a higher impingement gap for bottom surface controlled cooling. This is also suggested by the calculated heat transfer coefficient that shows an increase with the increase in pipe diameter and impingement gap for an increase in cooling rate. Therefore, for bottom surface jet impingement cooling, a higher impingement gap for any pipe diameter will give a better cooling rate for the steel austempering process.

A computational study of curvature effect on pressure drop of gas-liquid two-phase flow through 90 degree elbow

The CFD analysis of air-water two-phase flows was performed in a 90o vertical to horizontal elbows made of PVC with four different inside diameters (25 mm, 50 mm, 75 mm, and 100 mm) with six different curvature radius to diameter ratios (R/D) 1, 2, 4, 6, 8, and 10. Pressure drops were investigated at various upstream and downstream locations using computational, experimental, empirical methods. The most effective method in investigating and determining total pressure drop of two-phase flow in pipes and bends is considered to be computational study. The CFD simulations were performed using ANSYSY 19.2 FLUENT and a mixture model. The studies were conducted under the following two-phase conditions: mass quality from 1-50% and mass flux from 350-1000 kg/m2s. The results show that the impact of these significant parameters are important and dramatic specially at high curvature radius, mass flux and mass quality. The results of the CFD study demonstrated a substantial loss in energy and pressure as the fluid exits the elbow section, and also a higher drop in pressure observed at higher air velocity. Also, higher pressure drops were obtained with increasing pipe diameter in one side, and with decreasing R/D on the other side. Finally, the current results were verified with the empirical and experimental studies and a good agreement were obtained.

An Empirical Analysis of Heat Expulsion and Pressure Drop Attribute in Helical Coil Tube Using Nanomaterials

Water nanofluids were examined in a horizontal helical coil tube with constant temperature limitations for Dean values between 1000 and 10,000 to determine the rate of thermal radiation transmission and pressure drop characteristics. When conducting the tests, a variety of Al2O3 water nanofluid requirements were used, including varying mass flows, heat exchange rates for various nanoparticle volume concentrations, and changes in coil‐side drop in pressure versus coil‐side Dean number. Since nanoparticles have enhanced heat capacity, nanoparticles are developing as a transitional beginning of heat transfer fluids with significant potential in thermal management applications. Many applications require nanofluids to be used as heat transfer fluids; thus, scientists are concentrating their efforts on these fluids. The Reynolds values on the coil and shell were in the 1000 to 7000 range on either side of the wire. This paper discusses the impact of particle volume density on shell‐side flow temperatures, heat expulsion rate, and thermal conduction. The result shows that the average heat transfer rises by 13% and 17% when nanoparticle volume fraction percentage density is 0.1%, 0.2%, and 0.3 percent. The results demonstrate that reducing the mass flow by an increase in particle volume density, pipe diameter, and coil radius improves heat exchanger performance. The efficiency of the model is enhanced by increasing the diameter of the tube while simultaneously decreasing the diameter of the coil.

Spearmint (Mentha spicata) Cultivation in Decoupled Aquaponics with Three Hydro-Components (Grow Pipes, Raft, Gravel) and African Catfish (Clarias gariepinus) Production in Northern Germany

Mint (Mentha spicata) was cultivated in different hydroponic components: grow pipes, a raft and an ebb-and-flood gravel substrate system irrigated with aquaculture effluents from intensive African catfish (Clarias gariepinus) production under decoupled aquaponic conditions in northern Germany. The spearmint grew well and plant heights above ground were not significantly different between the gravel (57.7 ± 13.1 cm), raft (58.0 ± 17.7 cm) and grow pipe components (63.6 ± 9.9 cm). Root lengths and root fresh weights were two-fold and four-fold higher in raft (64.3 ± 20.5 cm; 42.8 ± 29.9 g) and grow pipes (59.4 ± 15.2 cm; 41.3 ± 25.7 g) compared with gravel substrate (29.7 ± 7.8 cm; 9.4 ± 9.4 g; raft = grow pipes > gravel). Spearmint leaf number was significantly higher in the grow pipes (770.0 ± 224.4) than in the gravel substrate (499.8 ± 228.4) with intermediate values in the raft. Significantly highest mean fresh biomass was found in the raft (1275.6 ± 33.4 g), followed by grow pipes (1042.0 ± 35.8 g) and gravel substrate (686.3 ± 98.2 g; raft > grow pipes > gravel). M. spicata, under aquaponics, grows best in grow pipe and raft components. An increase in pipe diameter for the grow pipes and a reduction in the channel height for the raft components could optimize aquaponic culture conditions for both industrial production and the hobby sector in the future.

Electrification hazard of turbulent pipe flow: Theoretical approach and numerical simulation

The present paper deals with electrostatic characteristics, i.e., space charge density and electrostatic potential under turbulent flow in pipes with and without leakage. This paper considers the charge conservation equation and proposes theoretical models able to calculate the space charge density of intact and leak pipes. The distributions of the space charge density and electrostatic potential are investigated through numerical simulation. For the case study used for validation purposes, the space charge density obtained by numerical simulations is compared with the experimental results. The results show that the proposed model is capable of calculating adequately the distribution of the space charge density in pipes. The effects of flow velocity and pipe diameter on the electrostatic characteristics of intact and leak pipes are then investigated. The results show that, for intact pipes, the maximum electrostatic potential appears in the central area of the pipe and increases slowly with the increase of the velocity, while the maximum potential decreases with the increase of the pipe diameter. For leak pipes, the maximum potential takes place at the leak aperture, and increases with the increase of flow velocity and pipe diameter. In order to reduce the possibility of electrostatic discharge, the flow velocity ought to be controlled below 2.5 m/s, and the pipes with smaller diameter shall be used as far as possible when meeting the requirement for use.

Laboratory Experimental Study on Influencing Factors of Drainage Pipe Crystallization in Highway Tunnel in Karst Area

The crystalline blockage of tunnel drainage pipes in a karst area seriously affects the normal operation of drainage system and buries hidden dangers for the normal operation of the tunnel. In order to obtain the influencing factors and laws of tunnel drainage pipe crystallization in a karst area, based on the field investigation of crystallization pipe plugging, the effects of groundwater velocity, drainage pipe diameter, drainage pipe material, and structure on the crystallization law of tunnel drainage pipe in karst area are studied by indoor model test. The results show that: (1) With the increase of drainage pipe diameter (20–32 mm), the crystallinity of drainage pipes first increases and then decreases. (2) With the increase of water velocity in the drainage pipe (22.0–63.5 cm·s−1), the crystallinity of the drainage pipes gradually decreases from 1.20 g to 0.70 g. (3) The crystallinity of existing material drainage pipe is: M3 (poly tetra fluoroethylene) > M2 (pentatricopeptide repeats) > M4 (high density polyethylene) > M1 (polyvinyl chloride); M8 (polyvinyl chloride + coil magnetic field) is used to change the crystallinity of drain pipe wall material. (4) When the groundwater flow rate is 34.5 cm·s−1, M1 (polyvinyl chloride) and M8 (polyvinyl chloride + coil magnetic field) can be selected for the tunnel drainage pipe. The research on the influencing factors of tunnel drainage pipe crystallization plugging fills a gap in the research of tunnel drainage pipe crystallization plugging. The research results can provide a basis for the prevention and treatment technology of tunnel drainage pipe crystallization plugging.

Effect of Heat Transfer between Potable Water Cold and the Environment Inside Building on Water Quality

In the face of a coronavirus pandemic, many buildings or facilities are closed. The sudden closing of schools, factories or offices has caused a reduction in the water consumption inside buildings. The lack of chlorinated water flowing through the pipes, combined with temperature changes, poses a real risk to potable water from the bacteria multiplication point of view. The contribution focuses on the requirements for the temperature of potable water cold (PWC) in the water pipeline system inside buildings. The main goal of the research is to evaluate the effect of heat transfer between the PWC and the surrounding air during the water stagnation. Temperature differences between the PWC and the indoor air in building are leading to the heat transfer by convection. The result of the heat transfer is an undesired increase of the PWC temperature. The paper assesses the increase in PWC temperature over time using two methodologies - mathematical analysis and computer simulation. The results show that with an increasing pipe diameter and insulation thickness, the temperature of PWC during stagnation increases more slowly. The article points out the fact that the first 10 mm of insulation has the greatest impact on preventing the heating of PWC from the surrounding environment. Regarding the material design of the pipeline, only small deviations in the results were calculated between steel and plastic pipe. Mathematical analysis and computer simulation show that the issue of PWC stagnation in the pipeline has a significant effect on the temperature and thus the quality of water in buildings.

Pressure drop characteristics of airlift in transporting particles

In this paper, the airlift process is divided into liquid-solid two-phase section and gas-liquid-solid three-phase section with the air inlet as the interface, and the corresponding pressure drop models are established based on the energy conservation and the phase hold-up equations. The results show that the pressure drop decreases rapidly first and then tends to be constant with the increase of pipe diameter in both two-phase and three-phase sections. The pressure drop in the two-phase section is less affected by the air superficial velocity and the immersion rate, while the pressure drop in the three-phase section decreases with the increase of the air superficial velocity and increases with the increase of the immersion rate. In addition, whether in the two-phase or three-phase sections, the measured pressure drop results are in good agreement with the calculated values, especially under the conditions of low air superficial velocity and high immersion rate.

Sediment transport simulation and design optimization of a novel marsh shoreline protection technology using computational fluid dynamics (CFD) modeling

Coastal Louisiana has the nation's most fragile and valuable wetlands, whose loss represents 80% of the total losses in the United States. The severely restricted mobility of conventional shoreline protection structures makes them impossible to be redeployed. The Wave Suppression and Sediment Collection (WSSC) system is a novel technology of high mobility and compatible with existing shoreline protection technologies. Previous laboratory studies on WSSC showed great potential for wave reduction and sediment collection. The current study aimed to optimize the design parameters of WSSC using a validated computational model. A computational fluid dynamics (CFD) model was developed and validated using experimental data from the previous laboratory study. Then, a parametric analysis was conducted with a focus on the performance optimization of wave reduction and sediment collection with respect to pipe diameter and face slope. Simulation results showed that the wave reduction efficiency decreased with increasing pipe diameter and face slope. In contrast, the sediment transport efficiency was enhanced by increasing pipe diameter but was not affected significantly by varying face slopes.

Effect of the Diameter of Pressure-Balance Pipe on Axial Hydraulic Thrust

The axial hydraulic thrust has great influence on the safety and stability of a pump turbine. A common way to balance hydraulic thrust is to install a pressure-balance pipe, and the change in pipe diameter is one of the important factors affecting axial hydraulic thrust. In this paper, the influence of the diameter changes in a pressure-balance pipe on axial hydraulic thrust of a pump turbine, plus the seal clearance flow, is studied and analyzed under three work conditions, i.e., 100%, 75%, and 50% loads. It is found that under 100% and 75% load conditions, the axial hydraulic thrust increases vertically with the increase in pipe diameter; whereas, under 50% load condition, the axial hydraulic thrust increases first and then decreases with the increase in pipe diameter. The results aim to give guidelines for the choice of pressure-balance pipe diameters and to control the axial hydraulic thrust of a pumped-storage power station, so that the hydraulic excitation force can be better matched with the hydraulic mechanism.

A Novel Elastography Phantom Prototype for Assessment of Ultrasound Elastography Imaging Performance

The aims of this study were firstly to manufacture and evaluate a novel elastography test phantom and secondly to assess the performance of an elastography system using this phantom. A novel Leicester–St. Thomas’ Elastography Pipe (L-STEP) test phantom consisting of five soft polyvinyl acrylic–cryogel pipes of varying diameters (2–12 mm), embedded at 45° within an agar-based tissue-mimicking material was developed. A shear-wave elastography (SWE) scanner was used by two blinded operators to image and assess longitudinal sections of the pipes. Young's modulus estimates were dependent on the diameter of pipes and at superficial depths were greater than deeper depths (mean 98 kPa vs. 59 kPa) and had lower coefficients of variation (mean 21% vs. 53%). The penetration depth (maximum depth at which a SWE signal was obtained) increased with increasing pipe diameter. Penetration depth measurements had excellent inter- and intra-operator reproducibility (intra-class correlation coefficients >0.8) and coefficient of variation range of 2%–12%. A new metric, called the summative performance index, was defined as the sum of the ratios of the penetration depth/pipe diameter. The L-STEP phantom is suitable for assessing key aspects of elastography imaging performance: resolution, accuracy, reproducibility, depth dependence, sensitivity and our novel summative performance index.