Pipeline Diameter Research Articles

Small-scale district heating system as heat storage for decentralized solar thermal collectors during non-heating period

Solar thermal energy usage in the Baltic countries is currently low, so there is a need to find technically and economically feasible solutions to increase the appeal of this technology. Integration of solar energy into existing district heating systems is a way to increase the share of renewable energy sources while utilizing the existing infrastructure, thereby reducing capital investments, as well as mitigating the risk of solar collector overheating and eliminating the need for local storage tanks in buildings. This study presents a parametric study for evaluating the effectiveness of using a district heating system to store heat produced by decentralized solar thermal collectors and comparing the district solution to the traditional local solution. The TRNSYS 18 model was developed for this purpose. The model investigates the impact of different hot tap water demand profiles as well as pipeline diameters and lengths on system energy efficiency, showing a statistically significant difference (p < 0.05) between installing solar collectors on residential and restaurant or office roofs, and no significant difference (p = 0.24) between restaurant and office. The model shows that solar energy can be shared within a 500 m distance between neighborhoods and that a larger main pipeline diameter can increase overall system efficiency.

Optimizing large-scale hydrogen storage: A novel hybrid genetic algorithm approach for efficient pipeline network design

As hydrogen production technologies continue to advance, efficient and high-capacity hydrogen storage solutions become increasingly crucial. To address the complex optimization challenges in the design of large-scale hydrogen storage pipeline networks, the study introduces a mixed integer nonlinear optimization model inspired by hydrogen pipeline design optimization theory. The model not only focuses on optimizing network design parameters but also aims to minimize investment costs. To achieve this, the study proposes an innovative hybrid genetic algorithm that combines the Modified Feasible Directions Method (MFDM) and Genetic Algorithm Theory (GAT), specifically targeting the optimization of pipeline diameter's discrete distribution challenges. Comparative analyses with SUMT and GA algorithms demonstrate the superiority of the approach. In continuous space, the algorithm achieves a lower convergence cost of 232.4437 × 104 Yuan, while in discrete space, the cost further decreases to 212.1636 × 104 Yuan. Additionally, the study delves into the sensitivity of the HGA-MFDM algorithm to ambient temperature and wellhead temperature in hydrogen storage facilities. The analysis reveals that wellhead temperature has a more significant impact on pipeline network investment, whereas ambient temperature exhibits a more pronounced effect on iteration curves. The findings provide valuable insights for the precise adjustment and optimization of hydrogen storage pipeline networks in practical applications.

Visualized Experimental Study of Soil Temperature Distribution around Submarine Buried Offshore Pipeline Based on Transparent Soil

The temperature distribution around the offshore burial pipeline is an important factor affecting its safety design and economic operation. The traditional test method cannot obtain the continuous temperature distribution of soil owing to the constraints of placing measurement sensors in soil. The transparent soil model test is an alternative method to realize the visualization research of soil temperature. In this paper, a relationship between the temperature of transparent soil and pixel intensity was first established. Then, the transparent soil test and numerical simulation, considering the natural convection, were carried out to study the temperature distribution around the submarine pipeline during start-up and stable operation. The influence of buried depth and pipeline diameter was analyzed. The results suggest that the continuous temperature distribution can be obtained visually by using a transparent soil test, and the observed heating zone of influence extended to a radial distance of 2.6 pipe diameters. The numerical analysis results show that the influence zone of the temperature of pipeline is a distance of four pipeline diameters at a temperature difference of 45 °C. The buried depth and pipeline diameter have little influence on the influence zone. In addition, the contour curves of soil temperature around the pipeline with different diameter are similar in shape. With the decrease in the buried depth of pipeline, the temperature gradient of soil around the pipeline decreases, which is caused by the natural convection.

Numerical modeling of local scour around a subsea pipeline on cohesive seabed under steady currents

The present study introduces a numerical model for simulating local scour around a subsea pipeline on a cohesive seabed, representing a pioneering endeavor in the development of such a numerical model. The flow dynamics around the pipeline are solved using Reynolds-Averaged Navier–Stokes (RANS) equations with the SST k–ω turbulent model. Sediment movement on cohesive seabed is assessed through erosion rates, determined by an empirical formula derived from experimental data, rather than sediment transport rates typically used for non-cohesive sediment. Three different erosion rate formulas—linear, power law, and stochastic—are investigated in the simulation of the scour process. The numerical simulations are validated using laboratory data with artificial and marine sediments, demonstrating a satisfactory level of agreement in predicting scour bed profiles. Nevertheless, it is recommended to utilize the erosion rate formula that is calibrated to the specific sediment type based on experimental data for precise numerical prediction of scour process. The study reveals that the equilibrium scour depth is approximately a linear function of the bed shear stress, and the nondimensional time scale is inversely proportional to the bed shear stress within the specified range. Subsequently, an examination of the scale effect on the scour process with cohesive sediment around a pipeline is conducted. The results indicate that the nondimensional equilibrium scour depth marginally increases with larger pipeline diameter on cohesive seabed, contrary to the observed trend for non-cohesive sediments.

Failure analysis of local effusion corrosion in small diameter gas pipeline: Experiment and numerical

In the later stage of gas well production, water–gas ratio increases, liquid carrying capacity decreases, gas field water accumulates in pipes for a long time, and the corrosion environment of pipelines becomes more and more severe. On the basis of carbon dioxide corrosion, microbial corrosion in gas field water accelerates catalytic pitting and finally leads to serious internal corrosion of pipelines. Therefore, accurate prediction of fluid distribution and flow characteristics in pipes is of great significance for engineering applications. In this work, the location and morphology of the corrosion pit were determined by physicochemical analysis. A computational fluid dynamics (CFD) model was established by using VOF and RNG k-ε models to predict fluid distribution characteristics and fluid accumulation locations in pipelines. The results showed that: 1) Corrosion and perforation occurred in the position of pipeline fluid accumulation. 2) The main elements of the corrosion pit on the inner surface of the pipe sample are O, Fe, C, S and Cl. The main corrosive substances in the pipeline corrosion pit are FeCO3 and Fe2O3. 3) The low-lying areas and uphill sections are prone to corrosion. A decrease in the fluid velocity in the pipe and a corresponding increase in the gas–liquid ratio will result in a greater accumulation of liquid in the pipe. 4) Magnetic flux leakage (MFL) detection method can be used to detect the characteristics and distribution of pipeline corrosion defects and determine the corrosion area. The research results are of great significance to the safety evaluation of small diameter pipelines for gathering and transporting in oil fields.

ГИДРАВЛИЧЕСКИЙ РАСЧЕТ ТРУБОПРОВОДА С РАССРЕДОТОЧЕННЫМ СБРОСОМ РАССОЛА В АКВАТОРИЮ

When producing water using desalination technologies, significant volumes of highly concentrated brines are formed. The solution of the problem of wastes recycling is an important global issue for water protection organizations, and the studies of the last decade confirm this. The article discusses an environmentally friendly method of dispersed uniform brine discharge into the water area, presents the developed technical solution and describes the principle of its operation. As an example, the authors calculate the hole diameters of the distribution pipeline for uniform brine discharge along the length. We calculated the radius and the scattering jet rate at a given distance from the hole in the distribution pipeline. The difference in brine salt concentrations at a depth of 20 m from the discharge point between the background concentration in the sea and the salt concentration was found to be from 0.439 % to 0.524 % along the length of the discharge pipeline. Dissolution of brines to safe concentrations becomes even more intense in the presence of sea currents. The research results can be used in the design and operation of such systems.

A numerical study on hydrogen blending in natural gas pipeline by a T-Pipe

In order to study the flow blending and transporting process of hydrogen that injects into the natural gas pipelines, a three-dimensional T-pipe blending model is established and the flow characteristics are investigated systematically by the large eddy simulation (LES). Firstly, the mathematical formulation of hydrogen-methane blending process is provided and the LES method is introduced and validated by a benchmark gas blending model having experimental data. Subsequently, the T-pipe blending model is presented, and the effects of key parameters, such as the velocity of main pipe, hydrogen blending ratio, diameter of hydrogen injection pipeline, diameter of main pipe and operating pressure on the hydrogen-methane blending process, are studied systematically. The results show that, under certain conditions, the gas mixture will be stratified downstream of the blending point, with hydrogen at the top of the pipeline and methane at the bottom of the pipeline. In the no-stratified scenario, the mixing distance increases at lower hydrogen mixing ratio and larger diameter of the hydrogen injection pipe or the main pipe. Finally, based on the numerical results, the underlying physics of the stratification phenomenon during the blending process are explored and an indicator for stratification is proposed using the ratio between the Reynolds numbers of the natural gas and hydrogen.

Optimization of hydraulic parameters for pipeline system of hydropower station with super long headrace tunnel based on mayfly algorithm considering operational scenarios

AbstractThis paper studies the optimization of hydraulic parameters for pipeline system of hydropower station with super long headrace tunnel (HSSLHT) based on mayfly algorithm considering operational scenarios. Firstly, the state equation of HSSLHT under load disturbance is derived. The optimization design of hydraulic parameters for pipeline system based on mayfly algorithm is proposed. Then, the optimization of hydraulic parameters is conducted and analyzed. Finally, the effects of pipeline diameters and transfer coefficients of turbines on the optimization of hydraulic parameters for pipeline systems are revealed. The results show that the optimization of hydraulic parameters for pipeline system is a multiobjective problem, and the several objective functions exhibit significant conflicts. Compared to the firefly algorithm and genetic algorithm, the objective function under mayfly algorithm is improved by 14.7% and 5.1%, respectively. The mayfly algorithm can make the hydraulic parameters for the pipeline system reach the Pareto optimal solution under both load decrease condition and load increase condition. The diameter of penstock has an obvious influence on the robustness of dynamic performance of HSSLHT. When the diameter of penstock increases by 30%, the robustness of HSSLHT becomes worse and the robustness index deteriorates by 57%. The reason is that the flow inertia of penstock becomes smaller with the increase of diameter, and the flow inertia of penstock is favorable for resisting disturbance of HSSLHT. The coefficient of throttled orifice head loss and the lengths and head losses of headrace tunnel and penstock are the key hydraulic parameters for matching the operation of HSSLHT.

A novel data center free radiating system driven by waste heat and wind energy system (DCFRWWs) and its operation performance analysis

Refrigeration equipment for data centers consumes a significant portion of global electricity, resulting in high Power Usage Effectiveness (PUE) values and increased entropy of the data center. To address these challenges, this study proposes a novel data center free radiating system driven by waste heat and wind energy (DCFRWWs). This approach recovers low-grade heat energy from the hot air heated by the central processing units (CPUs) and transform it into work. Unlike conventional cooling systems, the DCFRWWs do not require additional energy to meet CPU cooling demands and can effectively suppress the entropy increase of the data center. The Bernoulli equation was used to establish the mathematical model for DCFRWWs, which explained the underlying mechanisms of pipeline wind speed and the influence of ambient wind speed and pipeline inlet temperature on system operating characteristics. In addition, this study employed pipeline height and diameter as decision variables, while maximizing exergy efficiency served as the optimization objective. To obtain the optimal pipeline size (height and diameter) that is effective under real-world experimental conditions, the optimization calculations were conducted using weather data from Qinhuangdao. To verify the reliability and accuracy of the model, an experimental system was constructed, and the simulation results indicated that the relative error rates for the three key parameters are as follows: pipeline wind speed (33.09%), pipeline inlet temperature (0.59%), and CPU temperature (3.85%). A single factor analysis was performed on 14 different operating conditions to analyze the operating characteristics of the DCFRWWs. Moreover, the applicability verification conducted in three distinct cities across different regions suggest that the system is indeed suitable for diverse settings. The DCFRWW system, utilizing the dual forces of the chimney effect of waste hot air in pipelines and the extraction force generated by unpowered roof ventilator, achieves the objective of free heat dissipation. Furthermore, the DCFRWWs can not only be applied in the field of data center cooling but also serves as a thermodynamic reference for low-grade waste heat recovery in other sectors, thereby further expanding the scope of direct utilization of wind energy.

Adiabatic gas transport in the long flow channels

The paper present the determination of the state parameters of natural gas at the pipeline inlet based on knowledge of the pressure and temperature at the receiving point. Natural gas transport will be carried out through an offshore section of a transmission pipeline. The equations of the Fanno flow model will be used to describe the thermodynamic parameters of the gas in the flow lines. The mathematical equations of the flow mentioned above models have been derived from an analysis of the mass, energy and momentum balance equations. They also take into account the viscous friction forces in the transported gas. Based on the carried out calculations, changes in the Mach number, pressure and velocity of methane transported along the analysed pipeline were determined. In addition, the total entropy gain in the analysed methane flow was determined. The novelty of the calculations presented is the use of the Fanno flow model, which considers a realistic adiabatic gas flow. This is in contrast to the isothermal flow model, which assumes an unchanging temperature of the transported gas. In the case under consideration, the adopting model was possible because of the similar temperature values of the gas flowing in the pipeline and the corresponding temperature values of the surrounding seawater. The fundamental advantage of the Fanno flow model is that it satisfies the mass balance of the flowing gas in each cross-section. Thus, the product of the velocity and density of the gas in a pipeline of constant diameter assumes a constant value.

APPLICATION OF FRACTAL GEOMETRY TO STUDY STRUCTURAL CHANGES OF GAS FLOWS

Due to insufficiently efficient gas drying at processing units for gathering and preparing well products, a sufficient amount of liquid may remain in the transported flows. During the transportation products from gas condensate fields from platforms to onshore gathering points, complications arise due to precipitation of the liquid phase or, conversely, gas separation in the moving flow. In this regard, the selection of an adequate transportation mode and pipe-line diameter is of great scientific interest. The presence of a liquid phase, on the one hand, can change the structural forms of flow through the pipeline, and on the other hand, liquid can accumulate in low sections of the route and thereby reduce the capacity of the pipeline. The liquid phase also accelerates corrosion processes on the inner surface of the pipeline. In connection with the above, early diagnosis of the presence of a liquid phase in gas flows transported through main pipelines remains relevant today and requires the development of appropriate criteria. In this work, based on real measurements in sections of the main gas pipeline, was studied the dynamics of the gas flow’s main thermodynamic parameters (flow temperature and pressure). Based on the conducted research, was identified a stable relationship between the presence of liquid in the gas flow and the fractal dimension of time series for temperature, flow and pressure. The result is a relatively simple tool for diagnosing the presence of liquid in transported flows. Keywords: gas pipeline, gas-liquid flows, structural forms of flow, fractal dimension.

Isolated slug traveling in a voided line and impacting at an end orifice

Driven by upstream high-pressure steam, liquid slugs in nuclear power plant pipelines impact the end orifice at high speed, leading to bursting pipelines and threatening the plant's safety. This research aimed to accurately and efficiently assess the dynamic behavior of an isolated slug driven by pressurized air in a voided line with an end orifice. An improved one-dimensional (1D) model for the slug motion and impact was established. The dynamic variation of the pressure at both the slug's tail and front, the variation of the slug length, and the frictional resistance coefficient in the model was obtained by three-dimensional (3D) computational fluid dynamics (CFD). Based on 27 cases with different pipeline diameters and tank pressures, it was observed that the driving air pressure had a quadratic relationship and that the slug length had a constant rate of decrease vs the slug tail displacement. Finally, the decrease in the driving air pressure behind the slug, the increase in the air pressure ahead of the slug, the holdup coefficient, and the friction factor obtained from the 3D CFD results were interpreted in the 1D model, and the velocity histories of the liquid slug were found to be in excellent agreement with the 3D CFD solutions.

Effect of reduced diameter pipeline and impeller position on the performance of reactor coolant pump

In the reactor coolant pump experiments, there are cases where different impellers are replaced on the same volute for experiments, but due to the different diameter of the impeller inlet, there will be a sudden expansion between the inlet pipeline and the impeller inlet, resulting in a decrease in the efficiency of the pump. In order to solve this problem, a scheme of using an inlet pipe with a reduced diameter structure and changing the position of the impeller was proposed, and based on the three-dimensional incompressible Reynolds N-S equation, the reactor coolant pump device was numerically simulated by CFD software. The data simulation results of the reduced diameter structure, straight pipe flow field and changing the position of the impeller were compared with the model experiments, and the reliability of the calculation results was verified. The results show that the inlet pipe with reduced diameter structure and the method of changing the position of the impeller can effectively solve the problem of efficiency decline caused by the sudden expansion of the flow channel.

Simulation of water hammer in long distance water transmission pipeline based on Flowmaster

Long distance water transportation projects are widely used in balancing water resources and other fields. However, the opening and closing of valves often causes significant pressure changes in the pipeline, whether it is positive or negative pressure, which can cause damage to the pipeline, thereby affecting the actual water transportation project. Therefore, based on the method of characteristics, this paper studies the influence of pipeline diameter, length, friction coefficient and valve closing time on the transient flow in the pipeline. The results indicated that the pressure pulsation inside the pipe is mainly concentrated at 0.4hz and its harmonics. In addition, the frequency with high amplitude mainly ranges from 2.5s to 10s, and the closer it is to the valve, the higher the amplitude at the node.

Parametric Optimization and Efficiency Assessment of Horizontal Earth Water Pipe Heat Exchanger (EWPHE) in the Context of Bangladesh

This study aimed to evaluate the efficiency of the Earth Water Pipe Heat Exchanger (EWPHE) system in Bangladesh through simulation and experimental work carried out at Joypurhat in Bangladesh during the coldest period of the year, January. Additionally, the study sought to establish the method for selecting optimal installation parameters of EWPHE to increase performance and efficiency. A simulation model was made in the TRNSYS (v16.0) platform to determine the optimum values of design parameters. The simulation was run by altering its operating parameters, such as the rate of water flow, length of the pipe, built materials of the pipe, and the diameter of the underground pipeline. According to the findings, pipe burial can be done to a depth of 3.5 meters to achieve optimal output. The results of comparing four distinct materials, namely GI, Steel, PVC, and HDPE, show that these materials' characteristics do not significantly affect how well the systems perform. Additionally, as the water flow rate is increased, it is shown that the EWPHE performance is declining. According to the simulation results, it is concluded that a pipe with a length of 50 meters would be sufficient in the proposed EWPHE system to reach an average temperature decrease from 35 °C to 27 °C. Subsequently, in the field experiment, the EWPHE system had an average efficacy of 55% throughout January, which is quite promising. Journal of Engineering Science 14(2), 2023, 79-88

Analyzing the Efficacy of Nickel Plating Coating in Hydraulic Pipeline Drag Reduction

This study delves into the drag-reducing properties of nickel plating coatings applied to hydraulic pipelines. To investigate the drag reduction characteristics of pipeline coatings, we designed a specialized experimental apparatus to conduct deceleration experiments. The primary objective was to systematically assess the drag reduction effect of varying coating thicknesses on liquid flow within the pipeline. Chemical nickel plating was employed for preparing drag reduction coatings with diverse thicknesses, achieved through precise adjustments in the composition and operating conditions of the plating solution. In the design of the experimental apparatus, careful consideration was given to crucial parameters such as the inner diameter of the pipeline, the inlet flow rate, and the control of experimental variables. It quantitatively assesses how varying coating thicknesses, flow velocities, and pipeline diameters impact the pipelines’ resistance to flow. By meticulously measuring the pressure differential across the pipeline, the research evaluates the extent of drag reduction afforded by the coatings and simultaneously elucidates the underlying mechanisms. Findings indicate a peak drag reduction rate of 5% under conditions of a 20 µm-thick nickel coating, 5 m/s flow velocity, and a 10 mm pipeline diameter. This study aims to comprehend how coatings affect linear losses along the pipeline, thereby establishing the groundwork for optimizing drag reduction technology. These outcomes highlight the coatings’ potential to mitigate linear losses due to shear stress during fluid transport, offering a viable solution to enhance hydraulic pipeline efficiency with significant industrial implications.

Insulation of feed water tank in arrangement of transportable boiler plant with direct-flow steam boiler

A transportable boiler plant is used to provide consumers with steam of high energy characteristics, while saving costs for the construction of stationary boiler houses. A transportable boiler plant can be placed in the conditions of the Far North on an oilfield site. It is therefore necessary to organize reliable and safe operation of the boiler house, consisting of a steam direct-flow boiler of the coil type, a feed pump, a feed water tank and other auxiliary elements of the thermal circuit. One of the important elements in the thermal circuit is the feed water tank, in which water accumulates after chemical purification. It is where the water is also heated, increasing the efficiency of the boiler. Methods for calculating the diameters of main steam pipelines and feed water pipelines are described. The theoretical foundations of the operation of the feed water tank, its use in thermal power plants, combined heat and power plants, district industrial and heating boilers using various thermal arrangements of the above-mentioned enterprises are considered. The operation of the feed water tank in the thermal circuit of a steam unit is discussed. A thermal circuit of an industrial boiler house has been designed to generate saturated steam for consumers using direct-flow steam boilers of the coil type. The diameters of the inlet and outlet pipelines of the storage tank are calculated. The effective thickness of thermal insulation required to minimize heat losses during operation of a transportable boiler plant has been determined. Modeling of the design of the feed water tank and heat losses through its surface is carried out. A 3D model of the designed tank is presented, as well as heat losses through the surface of the tank walls when using a thermal insulation material. The importance of using thermal insulation of various tanks for storing feed water, petroleum products, hydrocarbons and other various media is noted.

Numerical simulation of mixing effect of compressed air–foam gas–liquid mixer

This article investigated the effect of geometric structural parameters on flow patterns and pressure drops and gas–liquid mixing effects of gas–liquid mixing devices. The computational fluid dynamics software FLUENT was used to calculate the airflow inside the mixer of a compressed air–foam gas–liquid mixing device with different cone angles, foam flow rates, air inlet inclination angles, and pipeline diameters. The results obtained are the pressure distribution, the liquid volume fraction, and the liquid phase streamlines in the mixing device. The numerical simulation results showed that for a gas–liquid mixing device, the optimal inlet inclination angle was 60°–70°, and the mixing effect of an equal diameter mixer was better than that of a variable diameter mixer, but it would reduce the mixing efficiency of the air and foam. The optimal pipeline diameter of the conveying pipeline was 190 mm, and the optimal cone angle of the mixing device was 55°.

The effect of pipeline parameters of machines for applying liquid complex fertilizers on the drip-air mixture quality

The article is devoted to the study of a drip-air mixture flow through pipelines, namely, the determination of total pressure losses based on known values of the flow rates of the constituent phases or the loss coefficients of the constituent phases. The authors conclude that the conditions for introducing the drip-air mixture into the pipes do not affect the size of the flow structure stabilization area. It has been found that for small values of the air and liquid flow rates, the diameter and length of the pipeline, as well as its position, have a very significant effect on the flow structure of the two-phase mixture and on the average diameter of the droplets. For each pipeline length and diameter, there is a pulsation flow mode only at certain values of the air and liquid flow rates (Gv/Gl), moreover, the larger the diameter and length of the pipeline, the later the pulsation flow mode occurs. At high values Gv/Gl, the position, length, and diameter of the pipeline do not have a noticeable effect on the flow shape, the flow has a finely dispersed structure, pressure pulsation is practically absent.

APPLICATION OF MACHINE LEARNING FOR PREDICTING PRESSURE DROP IN FLUIDIZED DENSE PHASE PNEUMATIC CONVEYING

It is difficult to model the pressure drop that occurs in fluidized dense phase conveying (FDP) of powders because the flow involves several interactions among the solid, gas, and pipe wall. These interactions are challenging to include in a model. Pressure drop is influenced by geometrical, material, and flow properties. When used with different pipeline designs that have different pipeline lengths or diameters, the current models exhibit considerable inaccuracy. The current work explores how machine learning (ML) algorithms can estimate the pressure drop in the FDP conveying of particles. The network was trained using experimental data from pneumatic conveying, and it subsequently used that information to predict pressure drops. For estimating the pressure drop, four distinct ML algorithms-AdaBoost, CatBoost, gradient boosting, and random forest-were selected. AdaBoost, CatBoost, gradient boosting, and random forest models predicted the data of pressure drop with MAE of 20.72, 4.06, 4.68, and 3.0, respectively, for training as well as testing data. The AdaBoost model performed more poorly in predicting the pressure drop than other models considered for the study, with &amp;#177; 10&amp;#37; error margin while training and evaluating the data and &amp;#177; 10&amp;#37; error margin in validating the data.