Search results for: consolidation pressure
3789 CFD Modeling of Air Stream Pressure Drop inside Combustion Air Duct of Coal-Fired Power Plant with and without Airfoil
Authors: Pakawhat Khumkhreung, Yottana Khunatorn
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The flow pattern inside rectangular intake air duct of 300 MW lignite coal-fired power plant is investigated in order to analyze and reduce overall inlet system pressure drop. The system consists of the 45-degree inlet elbow, the flow instrument, the 90-degree mitered elbow and fans, respectively. The energy loss in each section can be determined by Bernoulli’s equation and ASHRAE standard table. Hence, computational fluid dynamics (CFD) is used in this study based on Navier-Stroke equation and the standard k-epsilon turbulence modeling. Input boundary condition is 175 kg/s mass flow rate inside the 11-m2 cross sectional duct. According to the inlet air flow rate, the Reynolds number of airstream is 2.7x106 (based on the hydraulic duct diameter), thus the flow behavior is turbulence. The numerical results are validated with the real operation data. It is found that the numerical result agrees well with the operating data, and dominant loss occurs at the flow rate measurement device. Normally, the air flow rate is measured by the airfoil and it gets high pressure drop inside the duct. To overcome this problem, the airfoil is planned to be replaced with the other type measuring instrument, such as the average pitot tube which generates low pressure drop of airstream. The numerical result in case of average pitot tube shows that the pressure drop inside the inlet airstream duct is decreased significantly. It should be noted that the energy consumption of inlet air system is reduced too.Keywords: airfoil, average pitot tube, combustion air, CFD, pressure drop, rectangular duct
Procedia PDF Downloads 1533788 Exploration on Extraction of Coalbed Seam in Water Sensitive Reservoir by Combustion of Coal Seams
Authors: Liu Yinga, Bai Xingjiab
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The conventional way to exploit coalbed methane is to drop reservoirs pressure through drainage, which means that reducing pressure through water drainage for coalbed methane desorption. However, it has many limitations. In this paper, the recovery by conventional way is low, in order to exploit water-sensitive reservoir, combustion of coal seam is proposed to increase recovery ratio, and then theoretical feasibility is elaborated through four aspects: temperature, pressure, superficial area, competitive adsorption, then given an example of water sensitive reservoir, results can be obtained that recovery is effectively improved through combustion of coal seam. At the same time, the suitability and efficiency of combustion of coal seam determine that it can be widely applied.Keywords: coalbed methane, drainage decompression, water-sensitive, combustion of coal seams, competitive adsorption
Procedia PDF Downloads 2563787 Reducing Pressure Drop in Microscale Channel Using Constructal Theory
Authors: K. X. Cheng, A. L. Goh, K. T. Ooi
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The effectiveness of microchannels in enhancing heat transfer has been demonstrated in the semiconductor industry. In order to tap the microscale heat transfer effects into macro geometries, overcoming the cost and technological constraints, microscale passages were created in macro geometries machined using conventional fabrication methods. A cylindrical insert was placed within a pipe, and geometrical profiles were created on the outer surface of the insert to enhance heat transfer under steady-state single-phase liquid flow conditions. However, while heat transfer coefficient values of above 10 kW/m2·K were achieved, the heat transfer enhancement was accompanied by undesirable pressure drop increment. Therefore, this study aims to address the high pressure drop issue using Constructal theory, a universal design law for both animate and inanimate systems. Two designs based on Constructal theory were developed to study the effectiveness of Constructal features in reducing the pressure drop increment as compared to parallel channels, which are commonly found in microchannel fabrication. The hydrodynamic and heat transfer performance for the Tree insert and Constructal fin (Cfin) insert were studied using experimental methods, and the underlying mechanisms were substantiated by numerical results. In technical terms, the objective is to achieve at least comparable increment in both heat transfer coefficient and pressure drop, if not higher increment in the former parameter. Results show that the Tree insert improved the heat transfer performance by more than 16 percent at low flow rates, as compared to the Tree-parallel insert. However, the heat transfer enhancement reduced to less than 5 percent at high Reynolds numbers. On the other hand, the pressure drop increment stayed almost constant at 20 percent. This suggests that the Tree insert has better heat transfer performance in the low Reynolds number region. More importantly, the Cfin insert displayed improved heat transfer performance along with favourable hydrodynamic performance, as compared to Cfinparallel insert, at all flow rates in this study. At 2 L/min, the enhancement of heat transfer was more than 30 percent, with 20 percent pressure drop increment, as compared to Cfin-parallel insert. Furthermore, comparable increment in both heat transfer coefficient and pressure drop was observed at 8 L/min. In other words, the Cfin insert successfully achieved the objective of this study. Analysis of the results suggests that bifurcation of flows is effective in reducing the increment in pressure drop relative to heat transfer enhancement. Optimising the geometries of the Constructal fins is therefore the potential future study in achieving a bigger stride in energy efficiency at much lower costs.Keywords: constructal theory, enhanced heat transfer, microchannel, pressure drop
Procedia PDF Downloads 3293786 Wear Behaviors of B4C and SiC Particle Reinforced AZ91 Magnesium Matrix Metal Composites
Authors: M. E. Turan, H. Zengin, E. Cevik, Y. Sun, Y. Turen, H. Ahlatci
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In this study, the effects of B4C and SiC particle reinforcements on wear properties of magnesium matrix metal composites produced by pressure infiltration method were investigated. AZ91 (9%Al-1%Zn) magnesium alloy was used as a matrix. AZ91 magnesium alloy was melted under an argon atmosphere. The melt was infiltrated to the particles with an appropriate pressure. Wear tests, hardness tests were performed respectively. Microstructure characterizations were examined by light optical (LOM) and scanning electron microscope (SEM). The results showed that uniform particle distributions were achieved in both B4C and SiC reinforced composites. Wear behaviors of magnesium matrix metal composites changed as a function of type of particles. SiC reinforced composite has better wear performance and higher hardness than B4C reinforced composite.Keywords: magnesium matrix composite, pressure infiltration, SEM, wear
Procedia PDF Downloads 3563785 Experimental and Theoretical Study of Melt Viscosity in Injection Process
Authors: Chung-Chih Lin, Wen-Teng Wang, Chin-Chiuan Kuo, Chieh-Liang Wu
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The state of melt viscosity in injection process is significantly influenced by the setting parameters due to that the shear rate of injection process is higher than other processes. How to determine plastic melt viscosity during injection process is important to understand the influence of setting parameters on the melt viscosity. An apparatus named as pressure sensor bushing (PSB) module that is used to evaluate the melt viscosity during injection process is developed in this work. The formulations to coupling melt viscosity with fill time and injection pressure are derived and then the melt viscosity is determined. A test mold is prepared to evaluate the accuracy on viscosity calculations between the PSB module and the conventional approaches. The influence of melt viscosity on the tensile strength of molded part is proposed to study the consistency of injection quality.Keywords: injection molding, melt viscosity, tensile test, pressure sensor bushing (PSB)
Procedia PDF Downloads 4703784 Lyapunov Exponents in the Restricted Three Body Problem under the Influence of Perturbations
Authors: Ram Kishor
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The Lyapunov characteristic exponent (LCE) is an important tool to describe behavior of a dynamical system, which measures the average rate of divergence (or convergence) of a trajectory emanating in the vicinity of initial point. To analyze the behavior of nearby trajectory emanating in the neighborhood of an equilibrium point in the restricted three-body problem under the influence of perturbations in the form of radiation pressure and oblateness, we compute LCEs of first order with the help of slandered method which is based on variational equation of the system. It is observed that trajectories are chaotic in nature due positive LCEs. Also, we analyze the effect of radiation pressure and oblateness on the LCEs. Results are applicable to study the behavior of more generalized RTBP in the presence of perturbations such as PR drag, solar wind drag etc.Keywords: Lyapunov characteristic exponent, RTBP, radiation pressure, oblateness
Procedia PDF Downloads 4353783 Thermal and Caloric Imperfections Effect on the Supersonic Flow Parameters with Application for Air in Nozzles
Authors: Merouane Salhi, Toufik Zebbiche, Omar Abada
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When the stagnation pressure of perfect gas increases, the specific heat and their ratio do not remain constant anymore and start to vary with this pressure. The gas does not remain perfect. Its state equation change and it becomes a real gas. In this case, the effects of molecular size and inter molecular attraction forces intervene to correct the state equation. The aim of this work is to show and discuss the effect of stagnation pressure on supersonic thermo dynamical, physical and geometrical flow parameters, to find a general case for real gas. With the assumptions that Berthelot’s state equation accounts for molecular size and inter molecular force effects, expressions are developed for analyzing supersonic flow for thermally and calorically imperfect gas lower than the dissociation molecules threshold. The designs parameters for supersonic nozzle like thrust coefficient depend directly on stagnation parameters of the combustion chamber. The application is for air. A computation of error is made in this case to give a limit of perfect gas model compared to real gas model.Keywords: supersonic flow, real gas model, Berthelot’s state equation, Simpson’s method, condensation function, stagnation pressure
Procedia PDF Downloads 5073782 Optimal Design of 3-Way Reversing Valve Considering Cavitation Effect
Authors: Myeong-Gon Lee, Yang-Gyun Kim, Tae-Young Kim, Seung-Ho Han
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The high-pressure valve uses one set of 2-way valves for the purpose of reversing fluid direction. If there is no accurate control device for the 2-way valves, lots of surging can be generated. The surging is a kind of pressure ripple that occurs in rapid changes of fluid motions under inaccurate valve control. To reduce the surging effect, a 3-way reversing valve can be applied which provides a rapid and precise change of water flow directions without any accurate valve control system. However, a cavitation occurs due to a complicated internal trim shape of the 3-way reversing valve. The cavitation causes not only noise and vibration but also decreasing the efficiency of valve-operation, in which the bubbles generated below the saturated vapor pressure are collapsed rapidly at higher pressure zone. The shape optimization of the 3-way reversing valve to minimize the cavitation effect is necessary. In this study, the cavitation index according to the international standard ISA was introduced to estimate macroscopically the occurrence of the cavitation effect. Computational fluid dynamic analysis was carried out, and the cavitation effect was quantified by means of the percent of cavitation converted from calculated results of vapor volume fraction. In addition, the shape optimization of the 3-way reversing valve was performed by taking into account of the percent of cavitation.Keywords: 3-Way reversing valve, cavitation, shape optimization, vapor volume fraction
Procedia PDF Downloads 3633781 Optimization of Temperature Coefficients for MEMS Based Piezoresistive Pressure Sensor
Authors: Vijay Kumar, Jaspreet Singh, Manoj Wadhwa
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Piezo-resistive pressure sensors were one of the first developed micromechanical system (MEMS) devices and still display a significant growth prompted by the advancements in micromachining techniques and material technology. In MEMS based piezo-resistive pressure sensors, temperature can be considered as the main environmental condition which affects the system performance. The study of the thermal behavior of these sensors is essential to define the parameters that cause the output characteristics to drift. In this work, a study on the effects of temperature and doping concentration in a boron implanted piezoresistor for a silicon-based pressure sensor is discussed. We have optimized the temperature coefficient of resistance (TCR) and temperature coefficient of sensitivity (TCS) values to determine the effect of temperature drift on the sensor performance. To be more precise, in order to reduce the temperature drift, a high doping concentration is needed. And it is well known that the Wheatstone bridge in a pressure sensor is supplied with a constant voltage or a constant current input supply. With a constant voltage supply, the thermal drift can be compensated along with an external compensation circuit, whereas the thermal drift in the constant current supply can be directly compensated by the bridge itself. But it would be beneficial to also compensate the temperature coefficient of piezoresistors so as to further reduce the temperature drift. So, with a current supply, the TCS is dependent on both the TCπ and TCR. As TCπ is a negative quantity and TCR is a positive quantity, it is possible to choose an appropriate doping concentration at which both of them cancel each other. An exact cancellation of TCR and TCπ values is not readily attainable; therefore, an adjustable approach is generally used in practical applications. Thus, one goal of this work has been to better understand the origin of temperature drift in pressure sensor devices so that the temperature effects can be minimized or eliminated. This paper describes the optimum doping levels for the piezoresistors where the TCS of the pressure transducers will be zero due to the cancellation of TCR and TCπ values. Also, the fabrication and characterization of the pressure sensor are carried out. The optimized TCR value obtained for the fabricated die is 2300 ± 100ppm/ᵒC, for which the piezoresistors are implanted at a doping concentration of 5E13 ions/cm³ and the TCS value of -2100ppm/ᵒC is achieved. Therefore, the desired TCR and TCS value is achieved, which are approximately equal to each other, so the thermal effects are considerably reduced. Finally, we have calculated the effect of temperature and doping concentration on the output characteristics of the sensor. This study allows us to predict the sensor behavior against temperature and to minimize this effect by optimizing the doping concentration.Keywords: piezo-resistive, pressure sensor, doping concentration, TCR, TCS
Procedia PDF Downloads 1763780 Effect of Boundary Condition on Granular Pressure of Gas-Solid Flow in a Rotating Drum
Authors: Rezwana Rahman
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Various simulations have been conducted to understand the particle's macroscopic behavior in the solid-gas multiphase flow in rotating drums in the past. In these studies, the particle-wall no-slip boundary condition was usually adopted. However, the non-slip boundary condition is rarely encountered in real systems. A little effort has been made to investigate the particle behavior at slip boundary conditions. The paper represents a study of the gas-solid flow in a horizontal rotating drum at a slip boundary wall condition. Two different sizes of particles with the same density have been considered. The Eulerian–Eulerian multiphase model with the kinetic theory of granular flow was used in the simulations. The granular pressure at the rolling flow regime with specularity coefficient 1 was examined and compared with that obtained based on the no-slip boundary condition. The results reveal that the profiles of granular pressure distribution on the transverse plane of the drum are similar for both boundary conditions. But, overall, compared with those for the no-slip boundary condition, the values of granular pressure for specularity coefficient 1 are larger for the larger particle and smaller for the smaller particle.Keywords: boundary condition, eulerian–eulerian, multiphase, specularity coefficient, transverse plane
Procedia PDF Downloads 2123779 Effect of Pressure and Glue Spread on the Bonding Properties of CLT Panels Made from Low-Grade Hardwood
Authors: Sumanta Das, Miroslav Gašparík, Tomáš Kytka, Anil Kumar Sethy
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In this modern century, Cross-laminated timber (CLT) evolved as an excellent material for building and high load-bearing structural applications worldwide. CLT is produced mainly from softwoods such as Norway spruce, White fir, Scots pine, European larch, Douglas fir, and Swiss stone pine. The use of hardwoods in CLT production is still at an early stage, and the utilization of hardwoods is expected to provide the opportunity for obtaining higher bending stiffness and shear resistance to CLT panels. In load-bearing structures like CLT, bonding is an important character that is needed to evaluate. One particular issue with using hardwood lumber in CLT panels is that it is often more challenging to achieve a strong, durable adhesive bond. Several researches in the past years have already evaluated the bonding properties of CLT panels from hardwood both from higher and lower densities. This research aims to identify the effect of pressure and glue spread and evaluate which poplar lumber characteristics affect adhesive bond quality. Three-layered CLT panels were prepared from poplar wood with one-component polyurethane (PUR) adhesive by applying pressure of 0.6 N/mm2 and 1 N/mm2 with a glue spread rate of 160 and 180 g/m2. The delamination and block shear tests were carried out as per EN 16351:2015, and the wood failure percentage was also evaluated. The results revealed that glue spread rate and applied pressure significantly influenced both the shear bond strength and wood failure percentage of the CLT. However, samples with lower pressure 0.6 N/mm2 and less glue spread rate showed delamination, and in samples with higher pressure 1 N/mm2 and higher glue spread rate, no delamination was observed. All the properties determined by this study met the minimum requirement mentioned in EN 16351:2015 standard.Keywords: cross-laminated timber, delamination, glue spread rate, poplar, pressure, PUR, shear strength, wood failure percentage
Procedia PDF Downloads 1543778 Towards the Modeling of Lost Core Viability in High-Pressure Die Casting: A Fluid-Structure Interaction Model with 2-Phase Flow Fluid Model
Authors: Sebastian Kohlstädt, Michael Vynnycky, Stephan Goeke, Jan Jäckel, Andreas Gebauer-Teichmann
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This paper summarizes the progress in the latest computational fluid dynamics research towards the modeling in of lost core viability in high-pressure die casting. High-pressure die casting is a process that is widely employed in the automotive and neighboring industries due to its advantages in casting quality and cost efficiency. The degrees of freedom are however somewhat limited as it has been so far difficult to use lost cores in the process. This is right now changing and the deployment of lost cores is considered a future growth potential for high-pressure die casting companies. The use of this technology itself is difficult though. The strength of the core material, as chiefly salt is used, is limited and experiments have shown that the cores will not hold under all circumstances and process designs. For this purpose, the publicly available CFD library foam-extend (OpenFOAM) is used, and two additional fluid models for incompressible and compressible two-phase flow are implemented as fluid solver models into the FSI library. For this purpose, the volume-of-fluid (VOF) methodology is used. The necessity for the fluid-structure interaction (FSI) approach is shown by a simple CFD model geometry. The model is benchmarked against analytical models and experimental data. Sufficient agreement is found with the analytical models and good agreement with the experimental data. An outlook on future developments concludes the paper.Keywords: CFD, fluid-structure interaction, high-pressure die casting, multiphase flow
Procedia PDF Downloads 3283777 J-Integral Method for Assessment of Structural Integrity of a Pressure Vessel
Authors: Karthik K. R, Viswanath V, Asraff A. K
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The first stage of a new-generation launch vehicle of ISRO makes use of large pressure vessels made of Aluminium alloy AA2219 to store fuel and oxidizer. These vessels have many weld joints that may contain cracks or crack-like defects during their fabrication. These defects may propagate across the vessel during pressure testing or while in service under the influence of tensile stresses leading to catastrophe. Though ductile materials exhibit significant stable crack growth prior to failure, it is not generally acceptable for an aerospace component. There is a need to predict the initiation of stable crack growth. The structural integrity of the vessel from fracture considerations can be studied by constructing the Failure Assessment Diagram (FAD) that accounts for both brittle fracture and plastic collapse. Critical crack sizes of the pressure vessel may be highly conservative if it is predicted from FAD alone. If the J-R curve for material under consideration is available apriori, the critical crack sizes can be predicted to a certain degree of accuracy. In this paper, a novel approach is proposed to predict the integrity of a weld in a pressure vessel made of AA2219 material. Fracture parameter ‘J-integral’ at the crack front, evaluated through finite element analyses, is used in the new procedure. Based on the simulation of tension tests carried out on SCT specimens by NASA, a cut-off value of J-integral value (J?ᵤₜ_ₒ??) is finalised. For the pressure vessel, J-integral at the crack front is evaluated through FE simulations incorporating different surface cracks at long seam weld in a cylinder and in dome petal welds. The obtained J-integral, at vessel level, is compared with a value of J?ᵤₜ_ₒ??, and the integrity of vessel weld in the presence of the surface crack is firmed up. The advantage of this methodology is that if SCT test data of any metal is available, the critical crack size in hardware fabricated using that material can be predicted to a better level of accuracy.Keywords: FAD, j-integral, fracture, surface crack
Procedia PDF Downloads 1803776 Analytical Model for Vacuum Cathode Arcs in an Oblique Magnetic Field
Authors: P. W. Chen, C. T. Chang, Y. Peng, J. Y. Wu, D. J. Jan, Md. Manirul Ali
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In the last decade, the nature of cathode spot splitting and the current per spot depended on an oblique magnetic field was investigated. This model for cathode current splitting is developed that we have investigated with relationship the magnetic pressures produced by kinetic pressure, self-magnetic pressure, and changed with an external magnetic field. We propose a theoretical model that has been established to an external magnetic field with components normal and tangential to the cathode surface influenced on magnetic pressure strength. We mainly focus on developed to understand the current per spot influenced with the tangential magnetic field strength and normal magnetic field strength.Keywords: cathode spot, vacuum arc discharge, oblique magnetic field, tangential magnetic field
Procedia PDF Downloads 3163775 Optimization of Bifurcation Performance on Pneumatic Branched Networks in next Generation Soft Robots
Authors: Van-Thanh Ho, Hyoungsoon Lee, Jaiyoung Ryu
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Efficient pressure distribution within soft robotic systems, specifically to the pneumatic artificial muscle (PAM) regions, is essential to minimize energy consumption. This optimization involves adjusting reservoir pressure, pipe diameter, and branching network layout to reduce flow speed and pressure drop while enhancing flow efficiency. The outcome of this optimization is a lightweight power source and reduced mechanical impedance, enabling extended wear and movement. To achieve this, a branching network system was created by combining pipe components and intricate cross-sectional area variations, employing the principle of minimal work based on a complete virtual human exosuit. The results indicate that modifying the cross-sectional area of the branching network, gradually decreasing it, reduces velocity and enhances momentum compensation, preventing flow disturbances at separation regions. These optimized designs achieve uniform velocity distribution (uniformity index > 94%) prior to entering the connection pipe, with a pressure drop of less than 5%. The design must also consider the length-to-diameter ratio for fluid dynamic performance and production cost. This approach can be utilized to create a comprehensive PAM system, integrating well-designed tube networks and complex pneumatic models.Keywords: pneumatic artificial muscles, pipe networks, pressure drop, compressible turbulent flow, uniformity flow, murray's law
Procedia PDF Downloads 683774 Numerical Analysis of Fluid Mixing in Three Split and Recombine Micromixers at Different Inlets Volume Ratio
Authors: Vladimir Viktorov, M. Readul Mahmud, Carmen Visconte
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Numerical simulation were carried out to study the mixing of miscible liquid at different inlets volume ratio (1 to 3) within two existing mixers namely Chain, Tear-drop and one new “C-H” mixer. The new passive C-H micromixer is developed based on split and recombine principles, combining the operation concepts of known Chain mixer and H mixer. The mixing performances of the three micromixers were predicted by a preliminary numerical analysis of the flow patterns inside the channel in terms of the segregation or distribution of path lines. Afterward, the efficiency and the pressure drop were investigated numerically, taking into account species transport. All numerical calculations were computed at a wide range of Reynolds number from 1 to 100. Among the presented three micromixers, tear-drop provides fairly good efficiency except in the middle range of Re numbers but has high-pressure drop. In addition, inlets flow ratio has a significant influence on efficiency, especially at the Re number range of 10 to 50, Moreover maximum increase of efficiency is almost 10% when inlets flow ratio is increased by 1. Chain mixer presents relatively low mixing efficiency at low and middle range of Re numbers (5≤Re≤50) but has reasonable pressure drop. Furthermore, Chain mixer shows almost no dependence on inlets flow ratio. Whereas, C-H mixer poses excellent mixing efficiency (more than 93%) for all range of Re numbers and causes the lowest pressure drop, On top of that efficiency has slight dependency on inlets flow ratio. In addition, C-H mixer shows respectively about three and two times lower pressure drop than Tear-drop and Chain mixers.Keywords: CFD, micromixing, passive micromixer, SAR
Procedia PDF Downloads 4763773 Numerical Investigations of Unstable Pressure Fluctuations Behavior in a Side Channel Pump
Authors: Desmond Appiah, Fan Zhang, Shouqi Yuan, Wei Xueyuan, Stephen N. Asomani
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The side channel pump has distinctive hydraulic performance characteristics over other vane pumps because of its generation of high pressure heads in only one impeller revolution. Hence, there is soaring utilization and application in the fields of petrochemical, food processing fields, automotive and aerospace fuel pumping where high heads are required at low flows. The side channel pump is characterized by unstable flow because after fluid flows into the impeller passage, it moves into the side channel and comes back to the impeller again and then moves to the next circulation. Consequently, the flow leaves the side channel pump following a helical path. However, the pressure fluctuation exhibited in the flow greatly contributes to the unwanted noise and vibration which is associated with the flow. In this paper, a side channel pump prototype was examined thoroughly through numerical calculations based on SST k-ω turbulence model to ascertain the pressure fluctuation behavior. The pressure fluctuation intensity of the 3D unstable flow dynamics were carefully investigated under different working conditions 0.8QBEP, 1.0 QBEP and 1.2QBEP. The results showed that the pressure fluctuation distribution around the pressure side of the blade is greater than the suction side at the impeller and side channel interface (z=0) for all three operating conditions. Part-load condition 0.8QBEP recorded the highest pressure fluctuation distribution because of the high circulation velocity thus causing an intense exchanged flow between the impeller and side channel. Time and frequency domains spectra of the pressure fluctuation patterns in the impeller and the side channel were also analyzed under the best efficiency point value, QBEP using the solution from the numerical calculations. It was observed from the time-domain analysis that the pressure fluctuation characteristics in the impeller flow passage increased steadily until the flow reached the interrupter which separates low-pressure at the inflow from high pressure at the outflow. The pressure fluctuation amplitudes in the frequency domain spectrum at the different monitoring points depicted a gentle decreasing trend of the pressure amplitudes which was common among the operating conditions. The frequency domain also revealed that the main excitation frequencies occurred at 600Hz, 1200Hz, and 1800Hz and continued in the integers of the rotating shaft frequency. Also, the mass flow exchange plots indicated that the side channel pump is characterized with many vortex flows. Operating conditions 0.8QBEP, 1.0 QBEP depicted less and similar vortex flow while 1.2Q recorded many vortex flows around the inflow, middle and outflow regions. The results of the numerical calculations were finally verified experimentally. The performance characteristics curves from the simulated results showed that 0.8QBEP working condition recorded a head increase of 43.03% and efficiency decrease of 6.73% compared to 1.0QBEP. It can be concluded that for industrial applications where the high heads are mostly required, the side channel pump can be designed to operate at part-load conditions. This paper can serve as a source of information in order to optimize a reliable performance and widen the applications of the side channel pumps.Keywords: exchanged flow, pressure fluctuation, numerical simulation, side channel pump
Procedia PDF Downloads 1323772 Pressure-Controlled Dynamic Equations of the PFC Model: A Mathematical Formulation
Authors: Jatupon Em-Udom, Nirand Pisutha-Arnond
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The phase-field-crystal, PFC, approach is a density-functional-type material model with an atomic resolution on a diffusive timescale. Spatially, the model incorporates periodic nature of crystal lattices and can naturally exhibit elasticity, plasticity and crystal defects such as grain boundaries and dislocations. Temporally, the model operates on a diffusive timescale which bypasses the need to resolve prohibitively small atomic-vibration time steps. The PFC model has been used to study many material phenomena such as grain growth, elastic and plastic deformations and solid-solid phase transformations. In this study, the pressure-controlled dynamic equation for the PFC model was developed to simulate a single-component system under externally applied pressure; these coupled equations are important for studies of deformable systems such as those under constant pressure. The formulation is based on the non-equilibrium thermodynamics and the thermodynamics of crystalline solids. To obtain the equations, the entropy variation around the equilibrium point was derived. Then the resulting driving forces and flux around the equilibrium were obtained and rewritten as conventional thermodynamic quantities. These dynamics equations are different from the recently-proposed equations; the equations in this study should provide more rigorous descriptions of the system dynamics under externally applied pressure.Keywords: driving forces and flux, evolution equation, non equilibrium thermodynamics, Onsager’s reciprocal relation, phase field crystal model, thermodynamics of single-component solid
Procedia PDF Downloads 2993771 The Association of Anthropometric Measurements, Blood Pressure Measurements, and Lipid Profiles with Mental Health Symptoms in University Students
Authors: Ammaarah Gamieldien
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Depression is a very common and serious mental illness that has a significant impact on both the social and economic aspects of sufferers worldwide. This study aimed to investigate the association between body mass index (BMI), blood pressure, and lipid profiles with mental health symptoms in university students. Secondary objectives included the associations between the variables (BMI, blood pressure, and lipids) with themselves, as they are key factors in cardiometabolic disease. Sixty-three (63) students participated in the study. Thirty-two (32) were assigned to the control group (minimal-mild depressive symptoms), while 31 were assigned to the depressive group (moderate to severe depressive symptoms). Montgomery-Asberg Depression Rating Scale (MADRS) and Beck Depression Inventory (BDI) were used to assess depressive scores. Anthropometric measurements such as weight (kg), height (m), waist circumference (WC), and hip circumference were measured. Body mass index (BMI) and ratios such as waist-to-hip ratio (WHR) and waist-to-height ratio (WtHR) were also calculated. Blood pressure was measured using an automated AfriMedics blood pressure machine, while lipids were measured using a CardioChek plus analyzer machine. Statistics were analyzed via the SPSS statistics program. There were no significant associations between anthropometric measurements and depressive scores (p > 0.05). There were no significant correlations between lipid profiles and depression when running a Spearman’s rho correlation (P > 0.05). However, total cholesterol and LDL-C were negatively associated with depression, and triglycerides were positively associated with depression after running a point-biserial correlation (P < 0.05). Overall, there were no significant associations between blood pressure measurements and depression (P > 0.05). However, there was a significant moderate positive correlation between systolic blood pressure and MADRS scores in males (P < 0.05). Depressive scores positively and strongly correlated to how long it takes participants to fall asleep. There were also significant associations with regard to the secondary objectives. This study indicates the importance of determining the prevalence of depression among university students in South Africa. If the prevalence and factors associated with depression are addressed, depressive symptoms in university students may be improved.Keywords: depression, blood pressure, body mass index, lipid profiles, mental health symptoms
Procedia PDF Downloads 583770 Numerical Study of Pressure Losses of Turbulence Drilling Fluid Flow in the Oil Wellbore
Authors: Alireza Mehdizadeh, Ghanbarali Sheikhzadeh
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In this paper the pressure loss of drilling fluid flow in the annulus is investigated. On this purpose the domains between two concentric and two eccentric cylinders are considered as computational domains. In this research foam is used as drilling fluid. Firstly simulation results for laminar flow and non Newtonian fluid and different density like 100, 200, 300 kg/m3 and different inner cylinder rotational velocity like 100, 200, 300 RPM is presented. These results are compared and matched with references results. The power law and Herschel Bulkly methods are used for non Newtonian fluid modeling. After that computations are repeated with turbulence flow considering. K- Model is used for turbulence modeling. Results show that in laminar flow Herschel bulkly model has best result in comparison with power law model. And pressure loss in turbulence flow is higher than laminar flow.Keywords: simulation, concentric cylinders, drilling, non Newtonian
Procedia PDF Downloads 5593769 High Pressure Processing of Jackfruit Bulbs: Effect on Color, Nutrient Profile and Enzyme Inactivation
Authors: Jyoti Kumari, Pavuluri Srinivasa Rao
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Jackfruit (ArtocarpusheterophyllusL.) is an underutilized yet highly nutritious fruit with unique flavour, known for its therapeutic and culinary properties. Fresh jackfruit bulb has a very short shelf life due to high moisture and sugar content leading to microbial and enzymatic browning, hindering its consumer acceptability and marketability. An attempt has been made for the preservation of the ripe jackfruit bulbs, by the application of high pressure (HP) over a range of 200-500 MPa at ambient temperature for dwell times ranging from 5 to 20 min. The physicochemical properties of jackfruit bulbs such as the pH, TSS, and titrable acidity were not affected by the pressurization process. The ripening index of the fruit bulb also decreased following HP treatment. While the ascorbic acid and antioxidant activity of jackfruit bulb were well retained by high pressure processing (HPP), the total phenols and carotenoids showed a slight increase. The HPP significantly affected the colour and textural properties of jackfruit bulb. High pressure processing was highly effective in reducing the browning index of jackfruit bulbs in comparison to untreated bulbs. The firmness of the bulbs improved upon the pressure treatment with longer dwelling time. The polyphenol oxidase has been identified as the most prominent oxidative enzyme in the jackfruit bulb. The enzymatic activity of polyphenol oxidase and peroxidase were significantly reduced by up to 40% following treatment at 400 MPa/15 min. HPP of jackfruit bulbs at ambient temperatures is shown to be highly beneficial in improving the shelf stability, retaining its nutrient profile, color, and appearance while ensuring the maximum inactivation of the spoilage enzymes.Keywords: antioxidant capacity, ascorbic acid, carotenoids, color, HPP-high pressure processing, jackfruit bulbs, polyphenol oxidase, peroxidase, total phenolic content
Procedia PDF Downloads 1683768 Adsorption Studies of Methane on Zeolite NaX, LiX, KX at High Pressures
Authors: El Hadi Zouaoui, Djamel Nibou, Mohamed Haddouche, Wan Azlina Wan Ab Karim Ghani, Samira Amokrane
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In this study, CH₄ adsorption isotherms on NaX or Faujasite X and exchanged zeolites with Li⁺(LiX), and K⁺(KX) at different temperatures (298, 308, 323 and 353 K) has been investigated, using high pressure (3 MPa (30 bar)) thermo-gravimetric analyser. The experimental results were then validated using several isothermal kinetics models, namely Langmuir, Toth, and Marczewski-Jaroniec, followed by a calculation of the error coefficients between the experimental and theoretical results. It was found that the CH₄ adsorption isotherms are characterized by a strong increase in adsorption at low pressure and a tendency towards a high pressure limit value Qₘₐₓ. The size and position of the exchanged cations, the spherical shape of methane, the specific surface, and the volume of the pores revealed the most important influence parameters for this study. These results revealed that the experimentation and the modeling, well correlated with Marczewski-Jaroniec, Toth, and gave the best results whatever the temperature and the material used.Keywords: CH₄ adsorption, exchange cations, exchanged zeolite, isotherm study, NaX zeolite
Procedia PDF Downloads 2423767 Investigation of Contact Pressure Distribution at Expanded Polystyrene Geofoam Interfaces Using Tactile Sensors
Authors: Chen Liu, Dawit Negussey
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EPS (Expanded Polystyrene) geofoam as light-weight material in geotechnical applications are made of pre-expanded resin beads that form fused cellular micro-structures. The strength and deformation properties of geofoam blocks are determined by unconfined compression of small test samples between rigid loading plates. Applied loads are presumed to be supported uniformly over the entire mating end areas. Predictions of field performance on the basis of such laboratory tests widely over-estimate actual post-construction settlements and exaggerate predictions of long-term creep deformations. This investigation examined the development of contact pressures at a large number of discrete points at low and large strain levels for different densities of geofoam. Development of pressure patterns for fine and coarse interface material textures as well as for molding skin and hot wire cut geofoam surfaces were examined. The lab testing showed that I-Scan tactile sensors are useful for detailed observation of contact pressures at a large number of discrete points simultaneously. At low strain level (1%), the lower density EPS block presents low variations in localized stress distribution compared to higher density EPS. At high strain level (10%), the dense geofoam reached the sensor cut-off limit. The imprint and pressure patterns for different interface textures can be distinguished with tactile sensing. The pressure sensing system can be used in many fields with real-time pressure detection. The research findings provide a better understanding of EPS geofoam behavior for improvement of design methods and performance prediction of critical infrastructures, which will be anticipated to guide future improvements in design and rapid construction of critical transportation infrastructures with geofoam in geotechnical applications.Keywords: geofoam, pressure distribution, tactile pressure sensors, interface
Procedia PDF Downloads 1693766 Continuous Blood Pressure Measurement from Pulse Transit Time Techniques
Authors: Chien-Lin Wang, Cha-Ling Ko, Tainsong Chen
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Pulse Blood pressure (BP) is one of the vital signs, and is an index that helps determining the stability of life. In this respect, some spinal cord injury patients need to take the tilt table test. While doing the test, the posture changes abruptly, and may cause a patient’s BP to change abnormally. This may cause patients to feel discomfort, and even feel as though their life is threatened. Therefore, if a continuous non-invasive BP assessment system were built, it could help to alert health care professionals in the process of rehabilitation when the BP value is out of range. In our research, BP assessed by the pulse transit time technique was developed. In the system, we use a self-made photoplethysmograph (PPG) sensor and filter circuit to detect two PPG signals and to calculate the time difference. The BP can immediately be assessed by the trend line. According to the results of this study, the relationship between the systolic BP and PTT has a highly negative linear correlation (R2=0.8). Further, we used the trend line to assess the value of the BP and compared it to a commercial sphygmomanometer (Omron MX3); the error rate of the system was found to be in the range of ±10%, which is within the permissible error range of a commercial sphygmomanometer. The continue blood pressure measurement from pulse transit time technique may have potential to become a convenience method for clinical rehabilitation.Keywords: continous blood pressure measurement, PPG, time transit time, transit velocity
Procedia PDF Downloads 3483765 Modeling of Hydraulic Networking of Water Supply Subsystem Case of Addis Ababa
Authors: Solomon Weldegebriel Gebrelibanos
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Water is one of the most important substances in human life that can give a human liberality with its cost and availability. Water comes from rainfall and runoff and reaches the ground as runoff that is stored in a river, ponds, and big water bodies, including sea and ocean and the remaining water portion is infiltrated into the ground to store in the aquifer. Water can serve human beings in various ways, including irrigation, water supply, hydropower and soon. Water supply is the main pillar of the water service to the human being. Water supply distribution in Addis Ababa arises from Legedadi, Akakai, and Gefersa. The objective of the study is to measure the performance of the water supply distribution in Addis Ababa city. The water supply distribution model is developed by computer-aided design software. The model can analyze the operational change, loss of water, and performance of the network. The two design criteria that have been employed to analyze the network system are velocity and pressure. The result shows that the customers are using the water at high pressure with low demand. The water distribution system is older than the expected service life with more leakage. Hence the study recommended that fixing Pressure valves and new distribution facilities can resolve the performance of the water supply systemKeywords: distribution, model, pressure, velocity
Procedia PDF Downloads 1213764 Experimental Study on Thermomechanical Properties of New-Generation ODS Alloys
Authors: O. Khalaj, B. Mašek, H. Jirková, J. Svoboda
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By using a combination of new technologies together with an unconventional use of different types of materials, specific mechanical properties and structures of the material can be achieved. Some possibilities are enabled by a combination of powder metallurgy in the preparation of a metal matrix with dispersed stable particles achieved by mechanical alloying and hot consolidation. This paper explains the thermomechanical properties of new generation of Oxide Dispersion Strengthened alloys (ODS) within three ranges of temperature with specified deformation profiles. The results show that the mechanical properties of new ODS alloys are significantly affected by the thermomechanical treatment.Keywords: hot forming, ODS, alloys, thermomechanical, Fe-Al, Al2O3
Procedia PDF Downloads 2743763 Effect of Volute Tongue Shape and Position on Performance of Turbo Machinery Compressor
Authors: Anuj Srivastava, Kuldeep Kumar
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This paper proposes a numerical study of volute tongue design, which affects the centrifugal compressor operating range and pressure recovery. Increased efficiency has been the traditional importance of compressor design. However, the increased operating range has become important in an age of ever-increasing productivity and energy costs in the turbomachinery industry. Efficiency and overall operating range are the two most important parameters studied to evaluate the aerodynamic performance of centrifugal compressor. Volute is one of the components that have significant effect on these two parameters. Choice of volute tongue geometry has major role in compressor performance, also affects performance map. The author evaluates the trade-off on using pull-back tongue geometry on centrifugal compressor performance. In present paper, three different tongue positions and shapes are discussed. These designs are compared in terms of pressure recovery coefficient, pressure loss coefficient, and stable operating range. The detailed flow structures for various volute geometries and pull back angle near tongue are studied extensively to explore the fluid behavior. The viscous Navier-Stokes equations are used to simulate the flow inside the volute. The numerical calculations are compared with thermodynamic 1-D calculations. Author concludes that the increment in compression ratio accompanies with more uniform pressure distribution in the modified tongue shape and location, a uniform static pressure around the circumferential which build a more uniform flow in the impeller and diffuser. Also, the blockage at the tongue of the volute was causing circumferentially nonuniformed pressure along the volute. This nonuniformity may lead impeller and diffuser to operate unstably. However, it is not the volute that directly controls the stall.Keywords: centrifugal compressor volute, tongue geometry, pull-back, compressor performance, flow instability
Procedia PDF Downloads 1543762 Assessment of Heart Rate, Blood Pressure and Percentage Oxygen Saturation in Young Habitual Shisha Smokers in Kano, Nigeria
Authors: B. I. Waziri, M. A. Yahaya
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Background: Practice of shisha smoking involves the use of a multi-stemmed instrument to smoke tobacco or non-tobacco herbal mixture where the smoke is designed to pass through water or other liquid before reaching the smoker. The presence of tobacco content and the use of charcoal when burning the ingredients in this popular practice necessitate for investigation of many physiological parameters of habitual shisha smokers in our environment. Methods: 103 young shisha smokers, regular in the practice for more than three years living in Nasarawa, Kano state, Nigeria, were recruited for the study. The controls were 100 university students (nonsmokers) match for age (18 - 30 years), sex and BMI (20 - 24) with the smokers. Participants with known history of cigarette smoking, cardiovascular or respiratory diseases were excluded. Ethical approval was obtained from the Ministry of Health, Kano Nigeria. Hear rate, blood pressure and percentage oxygen saturation (SPO₂) were measured using stethoscope, sphygmomanometer and pulse oximeter respectively. Data were analyzed using IBM SPSS version 20 and mean values of the measured parameters were compared between the smokers and controls using independent sample t-test. P-values < 0.05 were considered significant. Results: The mean Heart rate was found to be significantly higher (p = 0.01) in the shisha smokers (91.32 ± 0.84) compared to controls (79.19 ± 1.18). Systolic and diastolic blood pressure was also higher (p = 0.00) in the shisha smokers (128.75 ± 1.11 and 85.85 ± 0.78 respectively) compared to controls with the systolic and diastolic pressure of 116.64 ± 0.82 and 80.39 ± 0.83 respectively. SPO₂ was significantly lower (p = 0.00) in the shisha smokers (91.98% ± 0.42%) compared to the controls (97.98 ± 0.18). Conclusion: Habitual Shisha Smoking caused a significant increase in Heart rate, both systolic and diastolic blood pressure and a significant decrease in SPO2 among youth in Kano State, Nigeria.Keywords: blood pressure, heart rate, shisha, youth
Procedia PDF Downloads 1413761 Using Phase Equilibrium Theory to Calculate Solubility of γ-Oryzanol in Supercritical CO2
Authors: Boy Arief Fachri
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Even its content is rich in antioxidants ϒ-oryzanol, rice bran is not used properly as functional food. This research aims to (1) extract ϒ-oryzanol; (2) determine the solubility of ϒ-oryzanol in supercritical CO2 based on phase equilibrium theory; and (3) study the effect of process variables on solubility. Extraction experiments were carried out for rice bran (5 g) at various extraction pressures, temperatures and reaction times. The flowrate of supercritical fluid through the extraction vessel was 25 g/min. The extracts were collected and analysed with high-pressure liquid chromatography (HPLC). The conclusion based on the experiments are as: (1) The highest experimental solubility was 0.303 mcg/mL RBO at T= 60°C, P= 90 atm, t= 30 min; (2) Solubility of ϒ-oryzanol was influenced by pressure and temperature. As the pressure and temperature increase, the solubility increases; (3) The solubility data of supercritical extraction can be successfully determined using phase equilibrium theory. Meanwhile, tocopherol was found and slightly investigated in this work.Keywords: rice bran, solubility, supercritical CO2, ϒ-orizanol
Procedia PDF Downloads 3763760 Learning, Teaching and Assessing Students’ ESP Skills via Exe and Hot Potatoes Software Programs
Authors: Naira Poghosyan
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In knowledge society the content of the studies, the methods used and the requirements for an educator’s professionalism regularly undergo certain changes. It follows that in knowledge society the aim of education is not only to educate professionals for a certain field but also to help students to be aware of cultural values, form human mutual relationship, collaborate, be open, adapt to the new situation, creatively express their ideas, accept responsibility and challenge. In this viewpoint, the development of communicative language competence requires a through coordinated approach to ensure proper comprehension and memorization of subject-specific words starting from high school level. On the other hand, ESP (English for Specific Purposes) teachers and practitioners are increasingly faced with the task of developing and exploiting new ways of assessing their learners’ literacy while learning and teaching ESP. The presentation will highlight the latest achievements in this field. The author will present some practical methodological issues and principles associated with learning, teaching and assessing ESP skills of the learners, using the two software programs of EXE 2.0 and Hot Potatoes 6. On the one hand the author will display the advantages of the two programs as self-learning and self-assessment interactive tools in the course of academic study and professional development of the CLIL learners, on the other hand, she will comprehensively shed light upon some methodological aspects of working out appropriate ways of selection, introduction, consolidation of subject specific materials via EXE 2.0 and Hot Potatoes 6. Then the author will go further to distinguish ESP courses by the general nature of the learners’ specialty identifying three large categories of EST (English for Science and Technology), EBE (English for Business and Economics) and ESS (English for the Social Sciences). The cornerstone of the presentation will be the introduction of the subject titled “The methodology of teaching ESP in non-linguistic institutions”, where a unique case of teaching ESP on Architecture and Construction via EXE 2.0 and Hot Potatoes 6 will be introduced, exemplifying how the introduction, consolidation and assessment can be used as a basis for feedback to the ESP learners in a particular professional field.Keywords: ESP competences, ESP skill assessment/ self-assessment tool, eXe 2.0 / HotPotatoes software program, ESP teaching strategies and techniques
Procedia PDF Downloads 374