Pipe Loop Research Articles

Effect of irrigation commutative flow technology on reducing deposition and improving anticlogging performance of a flat labyrinth drip pipe

Abstract This paper proposes a commutative flow technology of drip irrigation in a looped pipe network. Switching the flow direction of the drip irrigation pipe can improve the flow velocity in the lateral, consequently washing up the sediment deposited in the lateral and flow channel of the emitter. Thus, this technology can reduce sediment deposition and prevent blockage of the drip irrigation pipe. To verify the effectiveness of the commutative flow technology, the drip irrigation experiment was conducted, and the unidirectional flow technology experiment was the control. At the end of the tests, the emitter average relative discharge (Dra) of the commutative and unidirectional flow drip irrigation pipes decreased to 92.8 and 62.9%, the emitter blocking rate was 7.7 and 35.9%, respectively; the total amount of sediment deposited in the commutative flow lateral was 37.5% of that in the unidirectional flow lateral. Compared with the unidirectional flow technology, the commutative flow technology could significantly mitigate the decline rate of flow discharge, and effectively reduce the emitter blockage rate and the lateral sediment amount. Thus, the application of the commutative flow technology in the drip irrigation field pipe network can improve irrigation quality and promote the development of muddy water drip irrigation.

Research on deterioration evolution trend of primary loop piping in nuclear power plant based on fusion health index

The perennial operation of nuclear power primary loop piping leads to deterioration of the piping and the potential risk of leakage. At present, there is no reliable technology to detect the leakage directly. This paper proposes a method to obtain the piping deterioration evolution trend based on the analysis of sets of data that can reflect real state of the piping. The specific method is to quantitatively construct a fusion health index model based on the improved Mahalanobis distance, which integrates the analytic hierarchy process and the entropy weight method. A prediction model combining convolutional neural networks and long short-term memory neural networks is established to make the trend analysis and prediction. The experimental results show that the method can better reflect the actual health state of the piping and effectively predict the deterioration evolution trend, which provides a specific reference value for ensuring the safe and stable operation of equipment.

Comparison of coupon and pipe rack studies for selecting corrosion control treatment

AbstractThis study directly compared the data obtained from coupon studies and flow‐through pipe rack studies from two sources in the Denver Water system. The pipe rack study was completed over multiple years using harvested lead service lines. The coupon studies were completed in about 2 months using pure lead coupons. Orthophosphate at 2 mg/L was found to reduce lead concentrations by about 81% in the pipe racks, whereas 74%–81% was observed in the coupons. At an orthophosphate dose of 1 mg/L lead concentrations were reduced by 62%–65% in the pipe loop and by 55%–75% in the coupons, pH at 8.8 reduced lead by 45%–60% in the pipe racks and by 27%–48% in the coupons. The pipe racks were able to give insights into the transition from one condition to another, which is time‐based and dependent on existing pipe scales. Both types of demonstration studies produced similar conclusions about treatment options. The pipe rack was more representative of conditions in the distribution system while the coupon studies were performed in a fraction of the time.

Bolt loading effects on the structural integrity assessment of defects in industrial components

Applied loads in bolted geometries of safety critical components can vary with time and operating conditions. Structural integrity and remaining life assessments of such components in aging industrial plants must consider the resultant changes in damage accumulation rates and acceptable defect sizes. Two case studies are presented that demonstrate the effect of bolt pre-load on creep and fatigue lives as well as on the acceptability assessments of defects. In the first case the sensitivity of creep damage accumulation and crack propagation rates to bolt pre-load in high temperature flanged connections are considered. Predicted results were found to compare well with actual damage quantified on a high pressure turbine loop pipe flange connection. It was shown that decreased pre-loads, in this case, leads to an increase the allowable safe defect size during assembly at room temperature. In contrast to this the second case study of corrosion fatigue cracking in a boiler water circulating pump illustrates that an increase in bolt pre-load leads to an increase in fatigue initiation life, a decrease in fatigue crack propagation rate and an increase in the acceptable defect size. Strain gauge measurements of bolt and casing strain, which correlated well with finite element calculations, indicated the necessity for close control of bolt pre-load during assembly to ensure specified levels are attained. In both cases metallurgical analysis and structural integrity assessments of cracked and excavated geometries were conducted which enabled limited continued operation of the components after which repairs and/or replacements will be implemented.

Evaluation of Rheology Measurements Techniques for Pressure Loss in Mine Paste Backfill Transportation

Understanding the rheology behavior of non-Newtonian mine paste backfill is critical to ensure its flowability in the pipeline distribution system. Several rheology measurements methods for paste backfill have been proposed in the literature to quantify the rheology properties. However, there is no definite conclusion on the best measurement method to correctly predict pressure loss in the paste backfill pipeline system with a high solid concentration. This study addresses the issue by comparing several rheology measurements techniques, i.e., coaxial rheometer with various configurations, vane viscometer, and slump and pipe loop tests, with regard to Bingham yield stress, Bingham plastic viscosity, and pressure loss using statistical analysis. The paste backfill samples are prepared from two different mine tailings: finer and coarser particles. The pressure loss from the pipe loop test along with Buckingham-Reiner transformation using the Darcy-Weisbach equation are used as reference properties. The results suggest that a simple slump test can accurately predict the Bingham yield stress for coarser tailing. At the same time, a coaxial rheometer with MVDIN cup is found to predict the Bingham paste properties accurately for finer tailing.

Amoeba & Biofilms in UK Chlorinated Drinking Water Distributions Systems: Impact on Water Safety

Amoeba-related diseases have been related with the presence of certain amoebas in domestic water, including drinking water. Biofilms in drinking water distribution systems are able to support amoeba growth by providing a food source and protecting them against disinfectants. Additionally, amoeba growth can be favoured by warm temperatures and climate change appears to contribute to its geographic spread. The presence of amoeba and its association with potential pathogenic bacteria was studied in a real-scale chlorinated DWDS. The test facility comprised three independent pipe loops fed with water from the local water supply and for this study a varied flow hydraulic profile was applied based on daily patterns observed in real UK distribution networks. The daily regime was repeated for a biofilm growth phase of 30 days. Amoeba viability was tested by a culture-based method, non-nutrient agar (NNA)-E. coli plates, and then confirm by qPCR using specific primers to detect species of amoeba including Naegleria and Acanthamoeba. Amplicon sequencing of the 16s rRNA gene was used to characterise the biofilm and planktonic bacterial communities. Several amoeba species belonging to the genera Acanthamoeba, Vermamoeba and Naegleria were identified in 30-day old biofilm samples. While the bacterial communities in biofilms were dominated by Variovorax, Pseudomonas and Aquabacterium. This study yielded new insights on the dynamics of amoeba and bacterial communities in DWDS. However, more research is required to accurately establish the impact of these inter-kingdom associations on human health.

The interplay of suspended sediment concentration, particle size and fluid velocity on the rapid deposition of suspended iron oxide particles in PVC drinking water pipes

The inner walls of drinking water pipes are often expected to be clean and controlled surfaces to assure safe water access to the public. However, these surfaces are typically contaminated with particulate materials and biofilms that eventually degrade water quality. While water utilities place significant efforts in identifying and flushing material deposits from compromised pipes, the development of effective preventive strategies is still limited by the lack of knowledge about material accumulation processes. The aim of this paper is to examine the interplay between suspended sediment concentration, particle size and fluid velocity and the attachment of suspended iron oxide particles in PVC drinking water pipes. For that purpose, a series of short experiments were completed, whereby water amended with a known concentration of selected and stable iron oxide particles was introduced in a full-scale pipe loop laboratory over a short period of time and both turbidity and suspended sediment concentration (SSC) were measured at the inlet and outlet of the pipe loop. Results showed that a selected fraction of the injected particles with sizes above a specific threshold in the range of 4.6 to 6.8 µm had not reached the downstream section of the pipe loop, but instead remained attached to the pipe walls. In addition, exponential decay of the SSC was observed to occur along the pipes and to cause most of the sediments to accumulate in the upstream section of the pipe loop. The research improved our understanding of the physical processes of particulate material accumulation in DWDSs, and it will help water utilities forecast and monitor material accumulation and discolouration potential.

Initial Formation and Accumulation of Manganese Deposits in Drinking Water Pipes: Investigating the Role of Microbial-Mediated Processes

Microbial Mn(II) oxidation occurs in areas with insufficient disinfectants in drinking water distribution systems. However, the overall processes of microbial-mediated Mn deposit formation are unclear. This research investigated the initial Mn(II) oxidation, deposit accumulation, and biofilm development in pipe loops fed with nondisinfected finished water for 300 days. The results show that it took 20 days for microbial Mn(II) oxidation and deposition to be initiated visibly in new pipes continuously receiving 100 μg/L Mn(II). Once started, the deposit accumulation accelerated. A pseudo-first-order kinetic model could simulate the disappearance of Mn(II) in well-mixed pipe loop water. The observed rate constant reached 2.81 h-1 [corresponding to a Mn(II) half-life of 0.25 h] after 136 days of operation. Without oxygen, Mn(II) in the water also decreased rapidly to 1.0 μg/L through adsorption to deposits, indicating that after the initial microbial formation of MnOx, subsequent MnOx accumulation was attributable to a combination of microbial and physicochemical processes. Compared to the no-Mn condition, Mn(II) input resulted in 1 order of magnitude increase in biofilm formation. This study sheds light on the increasingly rapid processes of Mn accumulation on the inner surfaces of water pipes resulting from the biological activity of Mn(II)-oxidizing biofilms and the build-up of MnOx with strong adsorption capacity.

Random Forest Slurry Pressure Loss Model Based on Loop Experiment

A reasonable arrangement of filling pipelines can solve the problems of low line magnification, a high flow rate, large pipe pressure, etc., in deep well filling slurry transportation. The transportation pressure loss value of filling slurry is the main parameter for the layout design of filling pipelines. At present, pressure loss data are mainly obtained through the loop pipe experiment, which has problems such as a large amount of labor, high cost, low efficiency, and a limited amount of experimental data. In this paper, combined with a new generation of artificial intelligence technology, the random forest machine learning algorithm is used to analyze and model the experimental data of a loop pipe to predict the pressure loss of slurry transportation. The degree of precision reaches 0.9747, which meets the design accuracy requirements, and it can replace the loop pipe experiment to assist with the filling design.

Numerical simulation of thermo-acoustic gas oscillation for nuclear application

Numerical simulations are performed to study the characteristics of thermo-acoustic oscillation of a gas confined in a loop-type pipe with the section of short and narrow channels. In order to simulate the irreversible heat exchange between the gas and the pipe wall, the compressible mass, momentum and energy conservation equations are solved in the loop pipe as well as the heat conduction equations in the pipe wall. Spontaneous oscillations are obtained when the temperature gradient along the narrow channel becomes large. It is found that the onset temperature of simulated thermo-acoustic oscillation agrees with that of the stability analysis and increases when the effect of gravity is not taken into account.

Modeling and analysis of a dual-acoustic-driver thermoacoustic heat pump

Thermoacoustic heat pumps (TAHPs) can be used for heating and/or cooling purposes. Current designs of travelling-wave TAHPs normally employ a single acoustic driver and rely on a looped pipe to establish and maintain the required acoustic field. The resultant system is thereby bulky and expensive, detracting from the structure simplicity and low-cost advantages of thermoacoustic technology. To address this issue, this paper investigates the dual-acoustic-driver concept that can significantly increase the system’s compactness. Theoretical analyses are conducted for the dual-acoustic-driver TAHP, and the acoustic and temperature fields in the thermoacoustic core are examined. Parametric studies are undertaken to investigate the effects of acoustic drivers on the acoustic and thermal characteristics of the TAHP. It is found that, as the frequency of acoustic drivers changes, the acoustic field in the thermoacoustic (TA) core could be dominated by a standing, traveling, or hybrid standing-traveling wave. The temperature distribution within the TA core and temperature difference between the core ends will change accordingly. Results show that the temperature difference is non-zero only when the acoustic field contains a traveling-wave component. To obtain a large temperature difference, the acoustic drivers should be driven near resonance frequencies at which the acoustic field is hybrid and the pressure amplitude is large. This study gains new insights into the working mechanisms behind the dual-acoustic-driver TAHP concept, paving the way for developing compact, efficient, and high-power-density TAHPs for industrial waste heat recovery.

Desalination of sea water using solar still

The consumption of fresh water is increasing at a rapid rate, but its availability is decreasing day by day. The present work is based on developing a low-cost prototype working model called solar still which desalinates brackish water through distillation. The fabrication of solar still installed at the terrace of BILL GATES Bhavan of Aditya Engineering College, involves the components, wooden box of volume - 0.048 m3, lined by Aluminium sheet 6 gauge coated with black paint, a parabolic reflector (44” x 34”), preheating tray (1 × 1 m), connecting pipes (1”), water collector (2 lit capacity) and glass cover. Sea water samples from Port area (sample-1) and Uppada (sample-2) of Kakinada Beach were collected for purification. The raw water is sent from the inlet valve into the looped pipe placed in the pre-heating tray and then the pre-heated water is discharged into the solar still where distillation takes place, later the desalinated water was collected at the collecting point. The laboratory analyses of purified water from solar still has shown the quality suitable for consumption according to IS 10500:2012 drinking water standards with Water Quality Index for sample 1 as 14.199, and for sample 2 it was 2.188, both of them designated as excellent in terms of quality. The cost of the entire setup was 1500/- which gives 1.5–2 liters of purified water in a day.

Insulated PEX-pipe loops for deicing on existing bridge deck using geothermal energy: Laboratory tests, modeling, and performance analyses

An external hydronic heating system utilizing geothermal energy is an innovative new method to de-ice in-service bridges that avoids detrimental environmental effects and damage to bridge deck structures stemming from chemical deicers and mechanical traction materials (e.g., sand). However, in these systems, the bottom surface of the bridge deck is usually fully covered by insulation materials and hence not accessible for visual bridge inspection. In this study, a new attached insulated, cross-linked polyethylene (PEX) pipe loop heating system is developed to heat existing bridges while maintaining a partly uncovered deck for visual inspection. The new loop consists of a PEX pipe, an aluminum plate, polyurethane foam insulation, and a high-density polyethylene jacket. Numerical simulations were first performed to determine the optimum shape and thickness of the insulation. Then the pre-made loop system was attached to the bottom surface of a concrete slab in a freezer box, where 62.3% of the slab bottom surface was covered by the system. A heated water bath was used to simulate the ground heat exchanger for heating the system. The heating tests were conducted at room temperatures of −2.78, −3.89, and −6.67 °C, with supplied water temperatures ranging from 24 to 45 °C. A 1-D steady-state thermal resistance model was then created to model the heat transfer processes and to estimate the slab surface temperatures. The results show that the deck surface heat flux fluctuated from 49.6 to 121.5 W/m2, depending on operating conditions and that an average of 16.3% of heat energy was transferred to the deck top surface. The results of misting tests indicate that the new system kept the bridge deck free from ice under mild winter conditions. These results demonstrate that the new insulated PEX pipe loop heating system is feasible for deicing existing bridges while minimizing the hindrance of bridge inspections.

Impact of pipe material on the wall reaction coefficients and its application in the rehabilitation of water supply system of San Pedro Nexapa, State of Mexico

Abstract One of the major challenges faced by water companies around the world is the high level of chlorine losses in distribution networks. This paper presents an experimental study to examine chlorine loss in different types of pipe materials and select the ones with low chlorine demand for the rehabilitation of the water distribution network of San Pedro Nexapa, State of Mexico. The materials investigated include: polyvinyl chloride (PVC), galvanized steel (GS), polypropylene (PP) and high-density polyethylene (HDPE). A 24-h chlorine consumption study was performed in a simulated water distribution network to assess the impact of wall reaction coefficient on chlorine decay. Four sets of independent pipe loops of 50 mm in diameter and 12 m in length were used. Two different scenarios were considered based on different initial chlorine concentration (1.21 mg/L and 1.60 mg/L). Samples were collected at each loop at two-hour intervals and physicochemical analyses were conducted. Results from the experimental distribution network showed that the wall coefficient values for GS, HDPE, PP and PVC were 0.165 h−1, 0.059 h−1, 0.043 h−1 and 0.026 h−1, respectively. Experimental results showed that wall reaction coefficient values depend on initial chlorine concentration and the characteristics of pipe material. The rate of free chlorine decay was found to be faster in steel pipe and slower in the plastic pipes. Based on its having the lowest chlorine demand compared with the other pipes, PVC pipe would be selected to rehabilitate Nexapa water distribution network, State of Mexico. The wall coefficients from the experimental study were incorporated into EPANET through four simulation runs to predict chorine decay of San Pedro Nexapa water distribution network, State of Mexico. In the PVC and PP pipes higher residual chlorine concentrations were observed that ranged from 0.30 to 0.90 mg/L and 0.50 to 0.95 mg/L, respectively. This study is important for utilities to operate their system effectively and protect public health.

New Design and Optimization of a Jet Pump to Boost Heavy Oil Production

In the Oil and Gas industry, installing pipe loops is a well-known hydraulic practice to increase oil pipeline capacities. Nevertheless, pipe loops could promote an unfavorable phenomenon known as fouling. That means that in a heavy oil-water mixture gathering system with low flow velocities, an oil-water stratified flow pattern will appear. In consequence, due to high viscosity, the oil stick on the pipe, causing a reduction of the effective diameter, reducing handled fluids production, and increasing energy consumption. As jet pumps increase total handled flow, increase the fluid velocities, and promote the homogenous mixture of oil and water, this type of pump could result attractive compared to other multiphase pump systems in reactivating heavy crude oil transport lines. Jet pumps are highly reliable, robust equipment with modest maintenance, ideal for many applications, mainly in the oil and gas industry. Nevertheless, their design method and performance analysis are rarely known in the literature and keep a high experimental component similar to most pumping equipment. This paper proposes a numerical study and the optimization of a booster multiphase jet pump system installed in a heavy oil conventional loop of a gathering system. First, the optimization of a traditionally designed jet pump, combining CFD simulation and optimization algorithms using commercials software (ANSYS CFX® and PIPEIT® tool), has been carried out. This method allowed evaluating the effect of multiple geometrical and operational variables that influence the global performance of the pump to run more than 400 geometries automatically in a reduced time frame. The optimized pump offers a substantial improvement over the original concerning total flow capacity (+17%), energy, and flow distribution. Then, the effect of the three jet pump plugin configurations in a heavy oil conventional trunkline loop was analyzed. Simulations were carried out for different driving fluid pressures and compared against a traditional pipeline loop’s performance. Optimum plugin connection increases fluid production by 30%. Finally, a new eccentric jet pump geometry has been proposed to improve exit velocities and pressure fields. This eccentric jet pump with the best connection was analyzed over the same conditions as the concentric optimized one. An improvement of 2% on handled fluid was achieved consistently with the observed uniform velocity field at the exit of the pump. A better total fluid distribution between the main and the loop line is obtained, handling around half of the complete fluid each.

Research on Deterioration Evolution Trend of Primary Loop Piping in Nuclear Power Plant Based on Fusion Health Index

Research on Deterioration Evolution Trend of Primary Loop Piping in Nuclear Power Plant Based on Fusion Health Index

Research on the On-Line Fracture Assessment of Cracked Primary Loop Pipes in Npps

Research on the On-Line Fracture Assessment of Cracked Primary Loop Pipes in Npps

Experimental investigation on thermal characteristics of a novel mesh flat-plate heat receiver in a solar power tower system

In solar power tower systems, the heating surface of a heat receiver is prone to local overheating, thermal fatigue, and thermal ratcheting under nonstationary, nonuniform, and high-heat-flow-density loads, resulting in failure of the heat receiver. Therefore, this paper proposes a novel high-temperature, mesh, flat-plate heat receiver (FPHR) comprising multiple micro heat pipe loops. A series of tests were conducted to investigate the heat transfer characteristics and cooling start-up performance of the mesh FPHR. The results indicate that the larger cooling rates can reduce successful start-up times by more than 12%, and the FPHR has excellent isothermal performance (<35.05 °C) and heat transfer performance, which can withstand high-heat-flow-density loads and effectively prevent the harm caused by thermal stress. In addition, the nonuniform heating condition has a greater impact on the isothermal performance of FPHR, and the maximum temperature difference of the heat absorption surface with the change of the tilt angle is only reduced by 2.03 °C. The efficiency of the FPHR can exceed 83.98% and the air outlet temperature can exceed 714.5 °C. The results will contribute to the further development of heat receivers used in solar power tower systems.

Thermo-economic analysis of geothermal heat pump system integrated with multi-modular water-phase change material tanks for underground space cooling applications

The geothermal heat pump system (GHPS) is cascaded with multi-modular water-phase change material (PCM) tanks to cool the underground shelter in the ordinary mode and emergency mode, respectively. Based on the load characteristic of an underground shelter in Beijing, China, the thermo-economic performance of the hybrid system in the two modes is investigated. By utilizing the Taguchi design method, the effect of pipe length, multi-modular water-PCM tank matrix (MMWPM), and cooling water flow ratio of the above-mentioned components on the energy and economic performance are explored and optimized. The result shows that considering 10 years’ operation, 75 % of the base ground heat exchanger (GHE) could guarantee the cooling water temperature within the limited range in the ordinary mode. In the emergency mode, although the buried pipe loop accounts for a small flow rate, e.g., with a value of 10 %, it effectively extends the effective discharging duration (EDD) of the hybrid cooling system by at least 97 %. The average initial cost per unit EDD in the emergency mode is selected as the most important evaluation index in this paper. The order of factors is flow ratio> GHE length> MMWPM. The superior GHE length, MMWPM, and their flow ratio are 2500 m, 3 × 4, and 3:7, respectively. Moreover, the interaction between factors has a descending order of GHE length × Flow ratio> GHE length × MMWPM > MMWPM × flow ratio. With the optimal design of the hybrid system, the initial cost per unit EDD decreased by 24.37 %. This study is expected to serve as a reference for the application of the hybrid system in the underground shelter, meeting the requirement of thermal camouflage and energy-saving requirement.

Numerical evaluation of expansion loops for pipe subjected to thermal displacements

Abstract The thermal expansion can lead to the high stress on the pipe. The problem can be overcome using expansion loops in a certain length depending on the material’s elastic modulus, diameter, the amount of expansion, and the pipe’s allowable stresses. Currently, there is no exact definition for the dimension of expansion loops design both for loop width (W) and loop footing height (H) sizes. In this study, expansion loops were investigated with using ratio of width and height (W/H) variations to understand pipe stress occurring on the expansion loops and the expansion loops’ safety factor. Relationship between non dimensional stress on the expansion loop pipe was studied numerically by finite element software on several working temperatures of 400oF, 500oF, 600oF, and 700oF. It can be found that stress occurring on the pipes increases as the increases of W/H of the expansion loops and results in a lower safety factor. The safety factor of the expansion loops pipe has a value of 1 when the ratio of loop width and loop footing height (W/H) value was 1.2 for a 16-inch diameter pipe. Stress occurring on the pipe increases with the increase of the working temperature. Expansion loops pipe designed for 400oF can still work well to handle thermal extension pipe occurring on 500oF.