Inlet Pipe Research Articles

Magnetohydrodynamic Energy Harvester for Low-Power Pipe Instrumentation

Smart pipes can be adopted as a solution to problems in water distribution systems. However, the real application of such a system is usually constrained by power delivery. In this article, a magnetohydrodynamic (MHD) energy harvester for low-power pipe instrumentation is developed. A theoretical model of the maximum power output containing parameters of water conductivity, flow velocity, magnetic flux density, and water channel volume is derived. To enhance the magnetic flux density, a magnetic concentrator is designed and carefully tuned to arrange the magnetic flux as we desire and magnify the magnetic flux density within the channels. A spiral flow diverter is proposed to reconfigure the original pipe flow pattern and divert the flow into the surrounding channels to enhance the flow velocity. After integrating the proposed improvements from different fields and globally optimizing the power output, a final design is prototyped and tested in the lab, which achieves a maximum power output of 87.47 nW with a 2-m/s pipe inlet velocity. To the best of our knowledge, this is the first MHD energy harvester for low-power sensor networks. Its great potential is demonstrated, and several potential enhancements to the power output are proposed and analyzed.

Numerical and experimental investigation of 3D unsteady flow fields of a low head axial flow turbine under different blade number

Low-head axial flow turbines (LHAFT) are important turbomachines suitable for converting low-head water (potential energy) into mechanical (kinetic) or electrical energy. The performance characteristics of this kind of turbine are an essential aspect of its design and operational life cycle. Nevertheless, pressure fluctuations within the turbine affect its operational reliability. Hence its fluctuation characteristics cannot be overlooked due to its influence on vibration, noise, and severity of performance. It is essential to investigate the zones associated with high unsteadiness and turbulence. Furthermore, blade number and variation in flow rate are other important, influential factors on the level of pressure fluctuations. Given the above, numerical and experimental investigation of pressure fluctuation intensities within the flow channels of the LHAFT model under different blade numbers was carried out in this study. The results posit that the pulsating pressure coefficient decreases gradually from the inflow to the guide vane but increases at the runner, then falls as the flow progresses in the outlet pipe. At the runner, the flow experienced the most irregular flow patterns in the turbine. All three runner cases were operated with nine guide vanes, but after one complete revolution, blade numbers z = 2, 3, and 4 revealed regular pressure fluctuations, respectively, in the stationary part (guide vane, inlet and outlet pipes). Regardless of the case study, nine (9) regular peaks and valleys of pressure pulses matching the number of vanes on the static vane were recorded in the runner flow passage. The flow interaction between the static vane and runner is responsible for the pressure fluctuation, which influences the turbine’s vibration and noise. The obtained results would be an essential reference to noise and vibration analytical studies in turbines to optimize them for improved operational reliability.

Frequency domain analysis of density wave oscillations for two-phase flow in a vertical tube

In order to investigate the boundary characteristics of density wave oscillations in nuclear reactor steam generators and boiler water-cooled wall tubes, a frequency domain method numerical calculation model applicable to different geometrical structures and operating parameters was developed. In order to make the results of the model more accurate, the state of the fluid at the outlet of the heated pipe and the time delay were fully considered on the basis of the traditional model. Depending on the physical properties of the fluid at the outlet of the heated pipe, the model calculation area was divided into single-phase, two-phase and superheated zones. Small-perturbation linearization and Laplace transform were performed on the conservation equations in the three regions. The Nyquist stability criterion was used in matlab software to judge the stability of the flow, and by varying the working parameters the flow instability boundary can be calculated. For a more in-depth study of density wave oscillations in heated pipes, the unstable boundary characteristics were analysed computationally for different influences such as pressure, mass flow rate, inlet subcooling degree and pipe geometry on the basis of model validation. In addition, the Nyquist function was used in Matlab to plot the Nyquist curve for different influencing factors and to analyse the stability margins for specific operating conditions. The unstable boundary characteristic diagram was obtained when the pressure was 5–10 MPa and the mass flux was 300–1300 kg·m−2·s−1. The calculated data was collated and mass flow rate and heat load boundary diagrams were plotted, which could visualise the boundary characteristics of the density wave oscillations under different operating conditions. In order to make the calculation results more applicable, Nsub and Npch were used to construct the dimensionless unstable boundary characteristic diagram. Results showed that the influence of inlet subcooling degree on flow stability is non-monotonic. In addition, the effects of factors such as pressure, mass flow rate and inlet throttling coefficient are monotonic.

Intelligent Identification of Cavitation State of Centrifugal Pump Based on Support Vector Machine

In order to perform intelligent identification of the various stages of cavitation development, a micro high-speed centrifugal pump was used as a research object for vibration signal analysis and feature extraction for normal, incipient cavitation, cavitation and severely cavitated operating states of the pump at different temperatures (25 °C, 50 °C and 70 °C), based on support vector machines to classify and identify the eigenvalues in different cavitation states. The results of the study showed that the highest recognition rate of the individual eigenvalues of the time domain signals, followed by time frequency domain signals and finally frequency domain signals, was achieved in the binary classification of whether cavitation occurred or not. In the multi-classification recognition of the cavitation state, the eigenvalues of the time domain signals of the four monitoring points, the time frequency domain signals of the monitoring points in the X-direction of the inlet pipe and the Y-direction of the inlet pipe are combined, and the combined eigenvalues can achieve a multi-classification recognition rate of more than 94% for the cavitation state at different temperatures, which is highly accurate for the recognition of the cavitation state of centrifugal pumps.

Experimental study on combustion characteristics of a fischer‐tropsch diesel/methanol reactivity controlled compression ignition mode engine

AbstractF‐T diesel is an alternative fuel with a high cetane number (CN) for internal combustion engines. Methanol has a low CN and contains oxygen. F‐T diesel and methanol are potential fuels for the reactivity controlled compression ignition (RCCI) engines. In a single‐cylinder 186FA compression‐ignition engine with a combination of methanol inlet pipe injection and F‐T diesel in‐cylinder injection, the combustion characteristics of the F‐T diesel/methanol RCCI mode engine are investigated. The results show that as methanol premixed ratio (MPR) increases, the ignition delay (ID) is prolonged at low load conditions, the maximum in‐cylinder pressure (Pmax) and indicated thermal efficiency (ITE) a decreased. When the MPR increases from 0% to 60%, the ID is extended by 1.7°CA, the Pmax decreases by 8.1%, and the ITE decreases by 1.1%. At high load conditions, MPR rises from 0% to 60%, combustion duration (CD) is shortened by 2.4°CA, Pmax is increased by 8.3%, and the ITE is increased by 1.7%. The fuel injection advance angle (IAA) of F‐T diesel significantly influences the combustion process of the RCCI engine. As the IAA increases, the ID is shortened at high loads, and the Pmax and the ITE are increased. When the MPR is 60% and the IAA is 14°CA, the ITE of the engine is increased by 2.04%, and the equivalent indicated fuel consumption rate(be) is reduced by 5.68% compared with the engine fueled with F‐T diesel under high loads.

Multi-indicator analysis of mechanical blood damage with five clinical ventricular assist devices

PurposeDevice-induced blood damage contributes the hemolysis, thrombosis and bleeding complications in patients supported with ventricular assist device (VAD). This study aims to use a multi-indicator method to understand how devices causes blood damage and identify the “hot spots” of blood trauma within VADs. MethodsComputational fluid dynamics (CFD) methods were chosen to investigate the hemodynamic features of five clinical VADs (Impella 5.0, UltraMag, CHVAD, HVAD, and HeartMate II) under the same clinical support condition (flow rate of 4.5L/min, pressure head around 75 mmHg). A comprehensive multi-indicator evaluation method including hemodynamic parameters, hemolysis model, thrombotic potential model and bleeding probability model was used to analyze blood damage and assess the hemodynamic performance and hemocompatibility of these VADs. ResultsSimulation results show that shear stress from 50 Pa to 100 Pa plays a major role in blood damage in Impella 5.0, UltraMag and CHVAD, while blood damage in HVAD and HeartMate II is mainly caused by shear stress greater than 100 Pa. Residence time was not the main factor for blood damage in Impella 5.0, and also makes a limited contribution to blood trauma in UltraMag and CHVAD, while it takes a critical role in elevating thrombotic potential in HVAD and HeartMate II. The distribution of regions of high hemolysis risk and high bleeding probability was similar for all these VADs and partially overlapped for high thrombotic potential regions. For Impella 5.0, regions with high hemolysis and bleeding risk were found mainly in the blade tip clearance and diffuser domains, high thrombotic potential regions were almost absent. For UltraMag, regions with high hemolysis, bleeding and thrombosis potential were found in two corners of the inlet pipe, the secondary flow passage, and the impeller eye. For CHVAD, the high-risk regions for hemolysis, bleeding and thrombosis are mainly in the inner side of the secondary flow passage and the middle region of the impeller passage. The narrow hydrodynamic clearance and impeller passage had a high risk of hemolysis and bleeding, and the clearance between the rotor and guide cone and the hydrodynamic clearance had high thrombotic potential. For HeartMate II, regions of high hemolysis risk and bleeding probability were found in the near-wall region of the straightener, the blade tip clearance and the diffuser domain. The corners of the inlet and outlet pipe and the straightener and diffuser regions had high thrombotic potential. ConclusionThe risk of hemolysis, bleeding and thrombosis for these five VADs, in increasing order, was Impella 5.0, UltraMag, CHVAD, HVAD, and HeartMate II. Flow losses caused by the rotor mechanical movement, chaotic flow and narrow clearances increase the blood damage for all these VADs. The multi-indicator analysis can comprehensively evaluate the VAD performance with improved assessment accuracy of CFD.

Gas-solid separation performance and structure optimization in 3D printed guide vane cyclone separator

• A 3D printed guide vane cyclone separator was designed. • Theory, experiment, and simulation were used to study the separation performance. • The pressure, velocity, energy, and particle movement were discussed. • The tangential velocity was the major influence of separating. • The optimized cyclone had higher separation performance and lower pressure drop. Low separation efficiency and large pressure drop are two common problems of cyclones. In this paper, a 3D printed guide vane cyclone separator was designed to study the separation efficiency, turbulent kinetic energy, and particle movement of particle group by experiment and simulation. The results shown that the tangential velocity was the major influence of separating. The bottom of the exhaust pipe was the main region of gas–solid separation and pressure drop. The separation efficiency and pressure drop were positively correlated with the inlet velocity and the particle radius of the fluid. The distribution of turbulent kinetic energy that leaded to the pressure drop loss was concentrated on the inlet of the exhaust pipe. The swirl has external and internal two directions. The optimized cyclone has a longer and narrower blade flow path to obtain higher separation efficiency, especially at low inlet velocity.

Numerical simulation study on the optimization of the central ejector intake tube

A CFD numerical simulation study was conducted for the primary flow non-axial inlet L/Y intake tube ejector. The effects of different configurations of the inlet piping on the secondary flow of the ejector were analyzed in terms of total pressure loss, separation zone volume, and velocity uniformity. The results showed that: the volume of the separation zone decreases with the increase of secondary flow total pressure. The L intake tube causes a larger separation zone under the same working condition. When the total pressure of secondary flow is 20kPa, the volume of the separation zone caused by the L intake tube reaches 15 times that of the Y intake tube, and the total pressure loss is 2.3 times that of the Y intake tube. A smaller separation zone has less effect on the flow field structure, resulting in better velocity uniformity in the mixing chamber inlet section of the Y intake tube ejector.

Experimental study on the ozonation of transformer oil in wastewater enhanced by hydrocyclone and cavitation

The treatment of transformer oil wastewater in the accident oil pond with ozone has no secondary pollution to the environment. The cavitation technique was used to enhance the oxygenation process and hydrocyclone separator to do the pretreatment. After transformer oil sewage enters the hydrocyclone, the separation efficiency reached up to 60%, which reduces the processing load of subsequent cavitation device. Through 10min cycle treatment of ozone in a cavitation device, the oil concentration of the imported wastewater was reduced from 50mg/L to below 5 mg/L, which has reached the Class-I discharge standard of industrial water. The optimal operation parameters of cavitation were studied by adjusting the inlet pipe gap and gas-liquid ratio of cavitation.

Optimization of technological parameters of vacuum chamber in order to increase the lining durability in conditions of the JSC EVRAZ NTMK converter shop

Modern metallurgical enterprises are interested in producing products with minimal unit costs, which include the costs of refractory materials. Reduction of unit costs is possible by increasing the durability of the lining of the metallurgical unit. One of the ways to increase durability is to increase the thickness of the working lining. However, for circulating vacuum degasser, the increase in the thickness of the lining of the submersible snorkels is limited by the size of the steel ladle and the technological parameters of steel processing. To solve the problem of changing the geometric dimension of submersible snorkels, it is necessary to study the processes of removing hydrogen from the melt. The paper considers the issues of calculating the rational dimensions of the inlet snorkel of the vacuum chamber of the circulating vacuum degasser. To determine the rational dimensions, a physical simulation of the metal processing process by vacuum in a circulating vacuuming unit was applied. The relationship between the technological parameters of the circulating vacuum system and the size of the inlet snorkel is determined. Based on the revealed patterns, the design of the inlet pipe was changed, which made it possible to reduce the specific costs of refractory materials without changing the technological parameters of vacuum steel processing.

Study on the Improvement of Fire-Fighting Tactics for the Stable Supply of Fire Extinguishing Water

The connected water pipe facility is an important fire extinguishing facility for supplying fire water to firefighters on the fire floor. However, there are cases where fire water is not supplied quickly, which is also caused by the inability to find the connection water pipe inlet owing to unclear regulations on the installation location of the connection water pipe facility fire safety standards. If the connected water pipe facility is not found, fire-fighting tactics involving ropes are used, which takes a lot of time. To improve this problem, we confirmed experimentally that fire extinguishing water can be quickly and stably delivered to fire suppression personnel using a water outlet (40 A) installed in an indoor fire extinguishing tank on the first floor of an apartment. Through the experimental results, the Fire Safety Standards (NFSC 502) for Connected Water Pipeline Facilities (NFSC 502) proposed a plan to improve the fire safety standards (new) that require installation of water outlets (65 A, rotating) in the indoor firebox on the first floor of the apartment. If the revised fire safety standards are applied to the new building, firefighters who arrive at the site can quickly and stably supply fire water through the connecting water pipe connection port (65 A, rotary type) installed in the indoor fire extinguishing tank.

Research on the Thermal Stratification Phenomenon at the Secondary Side of a Steam Generator in an Isolated Loop

In normal operation, there is no significant thermal stratification phenomenon in the tube bundle area of the steam generator of the nuclear power plant. However, this phenomenon is detected in marine nuclear power plant isolation loops in the presence of feedwater leakage. Therefore, an experiment was designed to verify the presence of thermal stratification, and the influence factors were analyzed by the RELAP5/MOD3.2 program. The results show that thermal stratification is mainly influenced by the initial water level at isolation, the initial pressure at isolation, the total leakage mass, and the internal circulation of the steam generator. Leakage flow has little effect on it. This phenomenon causes the coolant temperature at the primary side of the steam generator in the isolated loop to be lower than the temperature measured in the reactor inlet pipe or outlet pipe. This study aids the operator in determining the real coolant temperature at the primary side of the steam generator in the isolated loop and prevents reactivity insertion accidents when the isolated loop is put into operation.

Investigating the Effect of Producer Gas in Pipelines of Downdraft Gasifier

With energy demand and for promoting the energy supply to remote areas the fuel from biomass initiative is carried. Gasification technology is an efficient conversion technique for biomass resources to energy. The production of producer gas by gasification are used for various applications including electricity generation. Utilization of the Producer gas for applications involves the flow of gas through pipes from reactor to applications. During the flow, the producer gas is subjected to wet scrubbers and passes through various filters for gas clean-up. The pipelines suffer corrosion due to moisture deposits and chemical components in the Producer gas. In this paper, the influence of producer gas to the inner surface of pipelines in downdraft gasifiers is investigated. The inlet pipe exhibits reduction ranging 68 to 72 HRB in the hardness comparing to the outlet pipe ranging 77 to 78 HRB from the coarse filters.

Experimental and numerical study on the performance of a new dual-inlet gas–liquid cylindrical cyclone (GLCC) based on flow pattern conditioning

Gas-Liquid Cylindrical Cyclone (GLCC) is a compact and efficient separation device used in oil and gas separation field. A new dual-inlet GLCC which can change the flow area ratio was designed and examined. The liquid separation efficiencies under five flow area ratios were experimentally measured. The liquid film velocity distribution was measured by MATLAB PIVlab. The finite volume method (FVM) was used to discretize the control equations. The liquid film thickness, gas–liquid flow distribution ratio and liquid flow streamline were obtained. The simulated liquid film velocities were seen to be consistent with experimental observations. Experimental and simulation results showed that by changing the flow area ratio of the upper and lower inlet pipes, the flow distribution in the upper and lower inlet pipes changed, liquid entering the upper GLCC cylinder reduced, the liquid film tangential velocity near the lower inlet increased and the change of liquid film axial velocity tended to be stable. The new type of GLCC expanded the safe operational separation envelop (envelop of the no LCO).

SIMULASI ANALISIS VELOCITY ALIRAN FLUIDA PADA TANGKI REAKTOR NUKLIR MENGGUNAKAN METODE COMPUTATIONAL FLUID DYNAMICS (CFD)

Center for Applied Nuclear Science and Technology (Pusat Sains dan Teknologi Nuklir Terapan /PSTNT) is a work unit that is under and directly responsible to the Deputy for Nuclear Science and Applications of Nuclear Technology, National Nuclear Energy Agency. In PSTNT Bandung, the function of the tank is as a container to place the reactor components, the reactor shield for the heat exchanger and as a place for nuclear reactions to take place. In nuclear reactor tank flow distribution ocures in various velocity.The purpose of this practical work is to analyze the velocity of fluid flow in the reactor tank from the inlet flow to the bottom surface of the reactor and from the bottom surface to the top surface of the TRIGA 2000 reactor. The method used in this practical work is the Computational Fluid Dynamics (CFD) Velocity method. CFD is a method for simulating fluid flow. The method is processed numerically and then digitally modeled. In practice, the authors modeled and studied the conceptual design of the reactor system using CFD based on Gambit and Fluent applications in a reactor tank. GAMBIT is an application produced by fluent inc. which is useful for making a model and discrete (meshing) to be analyzed by numerical methods. Fluent is an application that can solve fluid flow cases with the results obtained after discretizing the GAMBIT application. The results by CFD shows the distribution of fluid flow from the inlet pipe to the bottom surface of the reactor tank then the flow rises to the top surface to the outlet pipe. The velocity of the fluid flow from the inlet flow to the bottom surface was getting smaller, and the smallest value was at the bottom of the nuclear reactor, by 0.164 m/s and the flow distribution from the bottom surface to the top surface of the velocity value in a nuclear reactor would be bigger by the largest value being on the top surface of the nuclear reactor is 2.9 m/s.

Research on Autopsy Results of over 10 Year Old Low Pressure Hollow Fiber Membrane from Domestic Water Treatment Plant

Objectives : In this study, membrane autopsy was performed for a parallel arrayed low-pressure membrane (microfiltration) filtration process that is actually applied to water treatment, to check out whether there are differences in the degree of membrane fouling due to the uneven flow rate into each module. Also, membrane foulants were evaluated quantitatively.Methods : In this study, autopsy was performed for over 10 year old membranes used for drinking water purification. In this way, the outer casings of membrane modules at different positions were disassembled and visually observed. In addition, In addition, the size of the pores and the porosity were investigated by taking a SEM (Scanning Electron Microscope) photograph for the new and the used membrane module fiber samples in different positions from the header pipe. The used membrane foulants were classified into organic and inorganic matters and quantitatively analyzed.Results and Discussion : As a result of visually observing inside the membrane module that has produced drinking water for over 10 years, the inside of the No. 1 membrane module close to the inlet was contaminated with black foulants. On the other hand, in the case of No. 10 membrane module located farthest from the header pipe inlet, no foulants were observed with the naked eye. Also, it was observed from SEM photograph results that there were large differences in the surfaces among No. 1, 4, 6, 8 and 10 MF module fibers.Conclusion : Even after periodic physical and chemical cleaning, it was concluded that the fouling levels were different each other in the parallel arrayed low-pressure membrane modules. In addition, the pore size distribution and porosities of the membrane modules may vary depending on the position.

CFD simulation on optimum material to fabricate the counter flow of Ranque–Hilsch vortex tube

The basic objective of the current investigation by using CFD simulation is to select the appropriate material to fabricate Vortex tubes in meteorological conditions, which can improve efficiency and performance. The simulation results of vortex tubes were used in obtaining the performance for various materials such as copper, stainlessteel, brass, PVC, CPVC, acrylic, nylon, and bronze. The ratio of length of the hot tube and inner diameter was chosen as (L/D) 40 with the consistent inner diameter of the hot tube as 15 mm. Compressed air is passed through an inlet pipe between 2 and 12 bars in the step of 2 bars. 2D CFD was developed and analyzed with Ansys Fluent to access the performance of the vortex tube. Finally, after evaluating all simulation values for eight materials for performance depending upon their physical properties varies in the sequence from copper–bronze–brass–stainless steel–CPVC–PVC–acrylic–nylon material.

APPLE JUICE CLARIFIED BY THE POLYMERIC FLOCCULANTS

Based on the research, a innovative method for processing apple juice has been proposed, which consists in the use of safe polymeric flocculants – polyethylene oxide and hydrolyzed polyacrylamide, which can increase the speed and degree of transparency and purification of apple juice from heavy metals in conditions of its turbulent flow in channel, which is the gap between the stator with inlet and outlet pipes and the rotor kinematically connected to the electric motor. The mechanism of increasing the flocculating ability of flocculants under conditions of detected turbulent transparency of apple juice makes it possible to develop ways to improve the consumer properties of both the flocculant and apple juices during transparency. A comprehensive assessment of the quality of apple juice illuminated by hydrodynamically activated polyethylene oxide and hydrolyzed polyacrylamide was carried out, namely: the features of changes in mineral, vitamin, physical and chemical composition and safety, which together form the nutritional value and consumer properties of the product, were studied. The results of sensory and qualimetric analysis of apple juice clarified by activated flocculants indicate that when apple juices are illuminated with polyethylene oxide and hydrolyzed polyacrylamide, changes are observed primarily in transparency and color. The obtained quantitative data characterizing the physical and chemical composition of apple juice and the content of heavy metals in apple juice clarified with hydrodynamically activated polyethylene oxide and hydrolyzed polyacrylamide meet the requirements for apple juice producers. The research results allow us to conclude that polymeric flocculants polyethylene oxide and hydrolyzed polyacrylamide are effective reagents that can be used for deep purification of apple juices from heavy metals. Based on the obtained data characterizing the residual concentration of polyethylene oxide in apple juice treated with polyethylene oxide with hydrodynamic activation in a flocculator, it was concluded that the hydrodynamic activation of the flocculant reduces its residual concentration by more than 1.5–2 times.

Optimization and Internal Flow Analysis of Inlet and Outlet Horn of Integrated Pump Gate

In order to improve the hydraulic performance of the integrated pump gate, the flow pattern of the inlet and outlet of the pump gate is improved. This paper adopts the SST k-ω turbulence model to numerically calculate the initial scheme of the integrated pump gate, verifies its internal flow pattern through experiments, then adds and optimizes the design of the inlet and outlet horn pipes of the integrated pump gate through orthogonal optimization. The research results conclude that the hydraulic performance of the integrated pump gate is significantly improved after adding the inlet and outlet horn. Under the design flow condition (Qd = 11.5 L/s), the efficiency of the pump gate increased from 60.50% to 67.19%, the head increased from 2.7569 m to 3.1178 m, the hydraulic loss in the inlet channel decreased from 0.064 m to 0.027 m, and the hydraulic loss in the outlet channel decreased from 1.337 m to 1.027 m. The optimized trumpet pipe can improve the inlet conditions of the pump while weakening the vortices in the outlet channel, thus improving the efficiency and safety of the integrated pump gate. The research results of this paper are of reference value for similar projects.

Hydraulic geometric optimization on stagnating flow at the inlet of main pipe of underground pumping station

The underground pumping station is widely used in many important fields. However, the stagnating flow caused by the sharp geometric gradient at the interface between the primary pump intake and the main pipeline not only causes the performance deteriorations of the whole pump station but also leads to safety and operational stability challenges. In this paper, the numerical model of the related hydraulic phenomena is presented, moreover, the effectiveness and accuracy of the numerical model are verified by comparing it with the experimental results. The simulation results indicate that the hydraulic geometry optimization scheme at the inlet of the main pipe with 0.10 D (inner diameter of the main pipe) local rounding contributes the best effect on the hydraulic efficiency and operation stability of underground pump stations. The results may give a reference for the design of underground pump stations and the optimization of hydraulic geometry in related fields.