Complex Piping Systems Research Articles

Aerosol depositional characteristics in piping assembly under varying flow conditions

In the event of a nuclear reactor accident, large amount of radioactivity in the form of fission products may get released to the piping assembly of primary heat transport system. These fission products mostly in the form of aerosol particles get deposited on the inner surface of the piping system due to various depositional processes. The removal processes in the complex piping system are controlled to a large extent by the thermal-hydraulic conditions like temperature, pressure and flow rates. These parameters generally vary with time and therefore must be carefully monitored to predict the aerosol behavior in the piping system. Experimental determination of the deposition fraction, interpretation of the role of controlling parameters and development/validation of theoretical models are key areas gaining constant attention among researchers. In the present work, experiments were conducted in a piping assembly consisting of bends and horizontal-vertical orientation at two different carrier gas flow rates. Deposition fractions in the test assembly were estimated and the role of different dynamical processes (thermophoresis, gravitation and bend impaction) was interpreted. The computational fluid dynamics modeling approach is used for theoretical simulation in this work. Aerosol behavior in terms of number concentration, particle size distribution, and particle deposition in the piping system was simulated with the computational fluid dynamics software ANSYS Fluent 16.0 and the results were compared with experimental measurements (wherever applicable).

Design and Modeling of a Parallel-Pipe-Crawling Pneumatic Soft Robot

Soft robots have unique advantages over traditional rigid robots and have broad application prospects in many fields, such as pipe inspections. Several of the reported pipe-crawling soft robots have long actuation periods and small locomotion speeds. Moreover, they lack active steering property to adapt to complex piping systems, such as T-shaped pipes. To solve the above problems, this paper proposes a novel parallel-pipe-crawling pneumatic soft robot consisting of three extensible pneumatic soft actuators and two flexible feet. The parallel structure and flexible feet allow the robot to reduce the number of steps in a crawling cycle. The extensible actuator allows the robot to change its body shape for active steering property. However, a complete mathematical model for soft robots with parallel structure is hard to establish. In this paper, the phenomenological modeling method is used to realize a mathematical model with high precision, limited calculation, and easy engineering applicability of the pipe-crawling soft robot. Then, the prototype of the robot is fabricated with the optimal structural parameters selected by finite element simulations. The static identification experiment shows that the average errors of the extended length and output force are 0.51 mm and 0.28 N, respectively. The crawling experiments in various scenarios show that the horizontal crawling speed is higher than 15 mm/s, the maximum load is 2.456 kg, and the minimum turning radius is 38.2 mm. The robot shows great potential for inspecting in complex pipes with high crawling efficiency, excellent flexibility, and strong adaptability by switching its crawling gaits.

Effect of pipe materials on disinfection by-products and bacterial communities during sulfamethazine chlorination in a pilot-scale water distribution system

Water research is usually done using simplified devices, e.g., beakers, in laboratory glassware, and thus may yield results that are not representative of real wastewater treatment plants that use complex pipe systems made of various materials. Therefore, here we studied for the first time the effect of different pipe materials on sulfamethazine chlorination and formation of disinfection by-products. We also studied the relationships between bacterial communities, pipe materials, sulfamethazine degradation, free chlorine decay and formation of disinfection by-products. Results show that the degradation of sulfamethazine was faster in pipes than in batch tests, due to the influences of sediment, iron and bacterial communities. Specifically, the total concentration of disinfection by-products after 22 h followed the order: 49.43 μg/L for stainless-steel pipe, 46.76 μg/L for ductile iron pipe, 39.12 μg/L for polyethylene pipe, and 19.22 μg/L for batch tests. 16S rRNA microbial analysis showed that ductile iron and stainless-steel pipes had the highest operational taxonomic unit (OTU) richness. Microbial communities between polyethylene and ductile iron pipe had a relatively higher similarity. Sphingomonas and Actinobacteria slowed down the decay of free chlorine in the stainless-steel pipe, which promoted the degradation of sulfamethazine. Mycobacterium and Pseudomonas are the dehalogenation-related bacteria, which reduced the formation of distribution by-products in polyethylene pipe.

Delineation of Agricultural Drainage Pipe Patterns Using Ground Penetrating Radar Integrated with a Real-Time Kinematic Global Navigation Satellite System

Better methods are needed for mapping agricultural drainage pipe systems. Prior research on small test plots indicates that ground penetrating radar (GPR) is oftentimes capable of detecting buried drainage pipes; however, the feasibility of employing this geophysical technique in larger field areas has not been adequately evaluated. Ground penetrating radar integrated with a Real-Time Kinematic (RTK) Global Navigation Satellite System (GNSS) may be an effective and efficient means of mapping drain lines within agricultural fields. Therefore, GPR-RTK/GNSS was tested in three agricultural settings; with Site 1 and Site 2 located in Beltsville, MD, USA and Site 3 near Columbus, OH, USA. Soils at the three sites ranged from silty clay loam to loamy sand. A GPR unit with 250 MHz antennas was used to detect drainage pipes, and at Sites 1 and 2, a physical GNSS base station was utilized, while a virtual base station was employed at Site 3. The GPR-RTK/GNSS configurations used in this study delineated a complex rectangular drainage pipe system at Site 1, with one set of drainage pipes oriented southwest-northeast and a second oriented southeast-northwest. At Site 2, a herringbone drain line pattern was outlined, and at Site 3, random drain lines were found. When integrated with RTK/GNSS, spiral or serpentine GPR transects (or spiral/serpentine segments of a GPR transects) were utilized to provide insight on drain line directional trends. Consequently, given suitable field conditions, GPR integrated with RTK/GNSS can be a valuable tool for farmers and drainage contractors needing to map subsurface drainage systems.

Vibration analysis of a complex fluid-conveying piping system with general boundary conditions using the receptance method

In this paper, a new set of six-variable linear partial differential equations of motion of fluid-conveying pipes with general boundary conditions are derived using the Hamilton principle and these equations are solved by the receptance method. The frequencies of the straight pipes conveying fluid with or without elastic supports are determined and the results are compared with experimental ones. Then a fluid-conveying, semi-circular pipe and complex piping system with different kinds of boundary conditions are studied. These pipes are divided into some straight pipe units and are assembled using the receptance method. The numerical results show that the receptance method is efficient for pipes with arbitrary geometrical layouts and support types, and once the dynamic receptance of the elastic support of a piping system is obtained via experiment, its dynamic stability at different fluid velocities can be analysed by the receptance method.

Water Leakage Detection for Complex Pipe Systems Using Hybrid Learning Algorithm Based on ANFIS Method

In most city water distribution systems, a considerable amount of water is lost because of leaks occurring in pipes. Moreover, an unobservable fluid leakage fault that may occur in a hazardous industrial system, such as nuclear power plant cooling process or chemical waste disposal, can cause both environmental and economical disasters. This situation generates crucial interest for industry and academia due to the financial cost related with public health risks, environmental responsibility, and energy efficiency. In this paper, to find a reliable and economic solution for this problem, adaptive neuro fuzzy inference system (ANFIS) method which consists of backpropagation and least-squares learning algorithms is proposed for estimating leakage locations in a complex water distribution system. The hybrid algorithm is trained with acceleration, pressure, and flow rate data measured through the sensors located on some specific points of the complex water distribution system. The effectiveness of the proposed method is discussed comparing the results with the current methods popularly used in this area.

SimHydraulics approach to water hammer problems with the development of new formulas for static pressure diameter coefficient

Water hammer analysis and prediction is of overriding importance for operation safety of hydraulic systems. Therefore, the verification of computer codes capability to model and simulate water hammer is a very interesting topic for the analysis of different fluid-filled pipeline systems. Until now, transient approach of SimHydraulics is not developed, and the validity of this approach against benchmark examples, has never been investigated in scientific literature. In this paper, a numerical model of a reservoir-pipelines-valve system is created using Matlab SimHydraulics software. The main component of this model is the Segmented Pipeline with wall compliance parameters: the viscoelastic process time constant τ and the static pressure diameter coefficient K P for which new formulas were derived and validated. The numerical model is performed to solve transient flow problems caused by closure of a valve and the obtained results are presented and compared with those using the method of characteristic. Also, the effectiveness of the transient model of SimHydraulics is evaluated by comparing the obtained numerical results with the most pertinent experimental results found in the literature. The proposed transient model was adapted for the investigation of more complex piping systems. The results of this study show the ability of the SimHydraulics model to predict the pressure oscillation behavior accurately in all cases considered. This study provides useful information for future research in pump transient simulation using SimHydraulics.

EGGSHELL COATED GREY CAST IRON FOR CORROSION APPLICATIONS

In many years, corrosion has been such issues for carbon steel. Eggshell waste is believed to be a potential coating material for carbon steel in many applications. This paper introducing the use of eggshell waste which contents a source of calcium carbonate as corrosion prevention coating material on the grey cast iron by utilizing electrophoretic deposition (EPD) method. Eggshell consisted of 94-95 % of calcium carbonate in the form of calcite and others. Thus, calcium carbonate precipitation can serve as naturally formed coating on the cast iron pipe and prevent diffusion of oxygen that can direct to corrosion. Besides, this method will also prevent the lengthy and complex corrosion control piping system. In this study, the eggshell has been successfully coated on the grey cast iron substrate with optimum condition of 80 V for 1 minute deposition time at the sintering temperature of 600°C. From the preliminary work, thin and uniform coating thickness were produced at 1 minute deposition time and moderate voltage values of 60 – 80V.

Analysis of Radiation Transport due to Activated Coolant in the ITER Neutral Beam Injection Cell

Detailed spatial distributions of the biological dose rate due to a variety of sources are required for the design of the ITER tokamak facility to ensure that all radiological zoning limits are met. During operation, water in the Integrated loop of Blanket, Edge-localized mode and vertical stabilization coils, and Divertor (IBED) cooling system will be activated by plasma neutrons and will flow out of the bioshield through a complex system of pipes and heat exchangers. This paper discusses the methods used to characterize the biological dose rate outside the tokamak complex due to 16N gamma radiation emitted by the activated coolant in the Neutral Beam Injection (NBI) cell of the tokamak building.Activated coolant will enter the NBI cell through the IBED Primary Heat Transfer System (PHTS), and the NBI PHTS will also become activated due to radiation streaming through the NBI system. To properly characterize these gamma sources, the production of 16N, the decay of 16N, and the flow of activated water through the coolant loops were modeled. The impact of conservative approximations on the solution was also examined. Once the source due to activated coolant was calculated, the resulting biological dose rate outside the north wall of the NBI cell was determined through the use of sophisticated variance reduction techniques. The AutomateD VAriaNce reducTion Generator (ADVANTG) software implements methods developed specifically to provide highly effective variance reduction for complex radiation transport simulations such as those encountered with ITER. Using ADVANTG with the Monte Carlo N-particle (MCNP) radiation transport code, radiation responses were calculated on a fine spatial mesh with a high degree of statistical accuracy. Advanced visualization tools were also developed and used to determine pipe cell connectivity, to facilitate model checking, and to post-process the transport simulation results.

Optimization of Piping Supports and Supporting Structure

Optimization of piping supports is a well-known problem. The paper considers the optimization of piping supports with respect to cost and the loads transmitted to the supporting structural elements, when the orientation of the supporting structure is to be determined. This is the case, when new structural elements need to be added to the existing building structure to support components and piping systems that come as a new addition to a nuclear plant. The analytical target cascading (ATC) method is used for the optimization, combining the support loads from different piping analyses in a hierarchical framework. It is shown that the ATC method can be used for an optimized location of structural elements simultaneously supporting complex piping systems and implemented in a structural analysis software.

Transient freezing of molten salts in pipe-flow systems: Application to the direct reactor auxiliary cooling system (DRACS)

The possibility of molten-salt freezing in pipe-flow systems is a key concern for the solar-energy industry and a safety issue in the new generation of molten-salt reactors, worthy of careful consideration. This paper tackles the problem of coolant solidification in complex pipe networks by developing a transient thermohydraulic model and applying it to the ‘Direct Reactor Auxiliary Cooling System’ (DRACS), the passive-safety system proposed for the Generation-IV molten-salt reactors. The results indicate that DRACS, as currently envisioned, is prone to failure due to freezing in the air/molten-salt heat exchanger, which can occur after approximately 20minutes, leading to reactor temperatures above 900°C within 4hours. The occurrence of this scenario is related to an unstable behaviour mode of DRACS in which newly formed solid-salt deposit on the pipe walls acts to decrease the flow-rate in the secondary loop, facilitating additional solid-salt deposition. Conservative criteria are suggested to facilitate preliminary assessments of early-stage DRACS designs. The present study is, to the knowledge of the authors, the first of its kind in serving to illustrate possible safety concerns in molten-salt reactors, which are otherwise considered very safe in the literature. Furthermore, and from a broader prospective, the analytical tools developed in this study can also be applied to examine the freezing propensity of molten-salt flows in other complex piping systems where standard, finite element approaches are computationally too expensive.

Investigating thermal mixing and reverse flow characteristics in a T-junction using CFD methodology

A three-dimensional (3-D) computational fluid dynamics (CFD) methodology is developed to simulate the thermal mixing and reverse flow characteristics in an in-house T-junction. Different steady-state turbulence models are adopted in the simulations and assessed against the measured data of temperature distributions at various cross-sections of the main pipe. The unsteady-state turbulence models may be suitable for resolving the amplitude and frequency of temperature oscillation in a T-junction. However, T-junctions are just one component in an entire complex piping system. The steady-state turbulence models therefore attract some interest for T-junction simulations in engineering applications. Two cases, with the flowrate combinations of 30/200 and 30/400 in the branch/main pipes, are used to validate CFD simulations with different turbulence models. The reverse flow from the branch back upstream of the T-junction intersection is more significant for the lower flowrate of the main pipe, which can be confirmed by both measured data and predicted results. Based on the temperature comparison of the measurements and the predictions, the v2f turbulence model is most suitable for capturing the flow reversal characteristics in the T-junction, while the realizable k–ε turbulence model reproduces the measured data more accurately for the T-junction with the higher flowrate in the main pipe and the lesser reverse flow. The present results can provide a useful reference for simulating the thermal mixing and reverse flow in a T-junction with various steady-state turbulence models.

Innovative Adsorption Chiller for Marine Applications: Design and Building

In this work, the design and building of an advanced adsorption chiller, developed for marine applications, is reported. The realization of this cooling system was financed by the T.E.S.E.O. (Efficient Technologies for Energy Sustainability and Environmental On Board) – P.O.N. (Research and Competition 2007/2013) project. The prototype, developed with the aim of increase the cooling power density (W/m3), has two main innovative features: a novel three-adsorbers, connected with a condenser and an evaporator, and a hybrid adsorber, with a coating of FAM AQSOA-Z02 and Silica Gel granis. The prototype was designed to produce a Cooling Power about 4 - 6kW, as function of the operating conditions. A complex system of pipes and valves was realized to manage the external hydraulic circuits, allowing to automatically perform the adsorption cycles, controlled by a control system, realized by the LabVIEW software by National Instruments.

Layered composite thermal insulation system for nonvacuum cryogenic applications

A problem common to both space launch applications and cryogenic propulsion test facilities is providing suitable thermal insulation for complex cryogenic piping, tanks, and components that cannot be vacuum-jacketed or otherwise be broad-area-covered. To meet such requirements and provide a practical solution to the problem, a layered composite insulation system has been developed for nonvacuum applications and extreme environmental exposure conditions. Layered composite insulation system for extreme conditions (or LCX) is particularly suited for complex piping or tank systems that are difficult or practically impossible to insulate by conventional means. Consisting of several functional layers, the aerogel blanket-based system can be tailored to specific thermal and mechanical performance requirements. The operational principle of the system is layer-pairs working in combination. Each layer pair is comprised of a primary insulation layer and a compressible radiant barrier layer. Vacuum-jacketed piping systems, whether part of the ground equipment or the flight vehicle, typically include numerous terminations, disconnects, umbilical connections, or branches that must be insulated by nonvacuum means. Broad-area insulation systems, such as spray foam or rigid foam panels, are often the lightweight materials of choice for vehicle tanks, but the plumbing elements, feedthroughs, appurtenances, and structural supports all create “hot spot” areas that are not readily insulated by similar means. Finally, the design layouts of valve control skids used for launch pads and test stands can be nearly impossible to insulate because of their complexity and high density of components and instrumentation. Primary requirements for such nonvacuum thermal insulation systems include the combination of harsh conditions, including full weather exposure, vibration, and structural loads. Further requirements include reliability and the right level of system breathability for thermal cycling. The LCX system is suitable for temperatures from approximately 4K to 400K and can be designed to insulate liquid hydrogen, liquid nitrogen, liquid oxygen, or liquid methane equipment. Laboratory test data for thermal and mechanical performance are presented. Field demonstration cases and examples in operational cryogenic systems are also given.

Математическое моделирование подъёма воды в капиллярах, имеющих форму цилиндрической вертикальной спирали

A plant xylem is a complex system of pipes in which the movement of water occurs both vertically and horizontally. Rectilinear capillaries are arranged vertically in the trunks of lots of plants. However, a stem crown growing upwards can execute an independent circular motion called circular nutation. Some plants always wind around the bearer resulting in the spiral growth. The xylem of such plants should conform to their curved parts. A spiral water rise occurs in the rectilinear stems of some plants as well. Currently, the calculation of the water rise in the spiral capillaries is not described in the scientific literature. The problem on the mathematical modeling of the water rise in capillaries having the form of a cylindrical spiral is solved in the paper. It is shown that more water moves through the spiral capillary than through the rectilinear and curvilinear capillaries of the same length.

Frequency modelling and solution of fluid–structure interaction in complex pipelines

Abstract Complex pipelines may have various structural supports and boundary conditions, as well as branches. To analyse the vibrational characteristics of piping systems, frequency modelling and solution methods considering complex constraints are developed here. A fourteen-equation model and Transfer Matrix Method (TMM) are employed to describe Fluid–Structure Interaction (FSI) in liquid-filled pipes. A general solution for the multi-branch pipe is proposed in this paper, offering a methodology to predict frequency responses of the complex piping system. Some branched pipe systems are built for the purpose of validation, indicating good agreement with calculated results.

Quantitative Risk Assessment in Iran’s Natural Gas Distribution Network

Natural gas (NG) is one of the widely used domestic fuels in most of the countries, and because of economical and environmental advantages, its consumption is continuously increasing. As a result, complex piping systems are being installed to transport and distribute the gas for end users. Pipelines carrying NG are a significant source of hazard for their adjacent society. The risk of this hazard could be high especially in distribution network and urban areas where the population density is high. The common causes of accident in NG distribution network are: third party interference, corrosion, fatigue, stress corrosion cracking (SCC), etc. Accident in network leads to leakage and release of NG and consequent injuries and losses. To prevent these adverse outcomes, the risks should be identified and assessed carefully, so that they can be controlled and managed properly. In this work, risk assessment of NG distribution pipelines was surveyed and quantitative methods were recommended for assessing the individual and societal risks of distribution network.

Leak-Before-Break Under Beyond Design Basis Seismic Loading

The Atucha II nuclear power plant is a unique pressurized heavy water reactor (PHWR) being constructed in Argentina. The original plant design was by Kraftwerk Union (KWU) in the 1970's using the German methodology of break preclusion. The plant construction was halted for several decades, but a recent need for power was the driver for restarting the construction. The United States Nuclear Regulatory Commission (US NRC) developed leak-before-break (LBB) procedures in standard review plan (SRP) 3.6.3 Revision 1 for the purpose of eliminating the need to design for dynamic effects that allowed the elimination of pipe whip restraints and jet impingement shields. This SRP was originally written in 1987. The US NRC is currently developing a draft Regulatory Guide on what is called the transition break size (TBS). However, modeling crack pipe response in large complex primary piping systems under seismic loading is a difficult analysis challenge due to many factors. The initial published work (Wilkowski et al., “Robust LBB Analysis for Atucha II Nuclear Plant,” 2011 ASME PVP Conference, July 17–21, Baltimore, MD) on the seismic evaluations for the Atucha II plant showed that even with a seismic event with the amplitudes corresponding to the amplitudes for an event with a probability of 1 × 10−6 per year, that a double-ended guillotine break (DEGB) was pragmatically impossible due to the high leakage rates and total loss of make-up water inventory. The critical circumferential through-wall flaw size in that case was 94% of the circumference. This paper discusses further efforts to show how much higher the applied accelerations would have to be to cause a DEGB for an initial circumferential through-wall crack that was 33% around the circumference. This flaw length would also be easily detected by leakage and loss of make-up water inventory. These analyses showed that the applied seismic peak-ground accelerations had to exceed 25 g's for the case of this through-wall-crack to become a DEGB during a single seismic loading event. This is a factor of 80 times higher than the 1 × 10−6 seismic event accelerations, or 240 times higher than the safe shutdown earthquake (SSE) accelerations.

Hierarchical Pipe System Disassembly Sequence Planning by Dynamic Self-Adaptive Tree Based Motion Planning

This paper represents a hierarchical pipe system disassembly method by using dynamic self-adaptive tree (DSAT) based motion planning to perform disassembly for a complex pipe system. A pipe system CAD model is prepared initially to indicate the environment of the disassembly procedure. The improved motion planning method provides basic algorithm support for indicating the feasible escape path of a single part. Our technic gradually reduces the complexity of the pipe system to generate a hierarchical structure which takes all geometric information of the system. The hierarchical structure is preserved and used for the generation of a disassembly relationship graph which indicates the feasible disassembly sequences.

Dynamics of complex pipe systems in a transverse liquid flux

The vibration of complex pipe systems in a transverse liquid flux is considered. The intermediate supports and their gaps are taken into account. The influence of the structural parameters (the distribution of the intermediate supports and their gaps) on the vibrational strength of the pipe assemblies in power equipment is investigated.