HP Ejector Research Papers - Academia.edu (original) (raw)

2024, International Journal of Refrigeration-revue Internationale Du Froid

Hydrofluidisation freezing is a novel and promising food processing technology. This freezing method offers a high product quality, mostly due to the short process times resulting from high heat transfer coefficients. Consequently, hydrofluidisation freezing time is relatively short. Nevertheless, comprehensive experimental studies of this method are not available in the current literature. Therefore, the scope of this study was to experimentally investigate the fluid flow inside a hydrofluidisation chamber. The construction of the test rig used for the presented analysis enabled particle image velocimetry (PIV) measurements of the process. The PIV method was used for velocity field measurements. These measurements were conducted for various mass flow rates of the coolant and for various ratios of the distance between the sample and the orifice (H) to the orifice diameter (d). The results showed that the H/d ratio has a strong influence on the velocity of the fluid near the sample walls. The velocity of the fluid rapidly decreased for H/d higher than 14.0. Moreover, the increase of the mass flow rate and, in consequence, the coolant Reynolds number for H/d exceeding 14.0 did not affect significantly the velocity field around the analysed sample. Hence, the gathered results showed the importance of the correct design of the HF chamber in order to maximise the fluid flow velocity around the processed objects. Moreover, various velocity profiles were analysed showing the velocity variation under the sample. The collected velocity profiles and velocity fields were considered suitable for the hydrofluidisation freezing CFD models validation.

2024

An ejector is a momentum-transfer device that requires no external mechanical input or moving parts. However, ejectors have low performance due to irreversibilities such as viscous losses and shocks in the primary stream and diffuser. It has previously been argued that by maintaining a constant rate of momentum change along the ejector duct, shock losses could be eliminated or at least minimised, and so the Constant Rate of Momentum Change (CRMC) ejector was introduced. The CRMC configuration appears to have significant potential, but the CRMC design prescription relies on: (1) an arbitrary choice for the constant rate of momentum change along the length of the duct; and (2) complete mixing between primary and secondary streams at the entrance

2024, International Review of Mechanical Engineering (IREME)

This work focuses on a numerical study of compressible subsonic flow in gas turbine annular diffusers. A diffuser is a diverging passage in which the flow is decelerated and the reduction in velocity head is converted to a rise in static pressure. Usually, for aircraft engines, and also many industrial engines, the length is a crucial restriction, resulting that diffuser shape should be the shortest possible distance. However, with an increase in divergence angle, stall losses arising from boundary-layer separation become more significant and the pressure recovery coefficient is affected. Hence, it is important to study the divergence angle as a function of the airflow behavior. In the numerical solution, mass, momentum and energy equations are discretized and solved employing the finite volume method, and the turbulence effects are taken into account using the realizable k- model with an enhanced wall treatment. Results showed that the annular diffuser performance is insensitive to Mach number for the divergence angle equal to 9°. On the other hand, the pressure recovery coefficient elevates as the Mach number increases for the divergence angle equal to 6°. The opposite phenomenon occurred for 12° diffuser due to the intense recirculation zones as the divergence angle increases.

2024

This study aims at finding an optimal exhaust diffuser design of a high altitude testing chamber for a low bypass turbofan engine (F404-402) with thrust pound force of 17,700 and air mass flow rate of 66kg/s ejecting at a speed of Mach 1.66. The final proposed ejector size has better pressure recovery characteristics and targets to reduce operational cost at engine performance testing. Conventional high altitude test chamber layout was adopted and first drawn in two dimensions using Autocad software so as to determine the gas path, the ejector frontal size was then determined from gas dynamics equations considering traditional gas ejection method where both the engine exhaust and cell cooling air are exhausted via the ejector. Modification to a smaller ejector with an alternative secondary cell cooling exhaust port was then performed and modelled in 3D using Solid Works software.

2024, Journal of the Korean Society of Propulsion Engineers

This research aims in finding a more optimal ejector size for evacuating engine exhaust gasses and 20% of the cell cooling air. The remaining 80% of cell cooling air pumped into the test chamber is separately exhausted from the test chamber via a discharge port fitted with flow control valves and vacuum pump. Unlike its predecessor this configuration utilizes a smaller capture area to improve pressure recovery. The modified ejector size has a diameter of 1100mm enough to evacuate 66kg/s jet engine exhaust in addition to about 20%, 24kg/s of the cell cooling air tapped from the sterling chamber. This configurations has an area ratio of the engine exit and ejector inlet of about 1.2. Simulation results of the proposed ejector configuration, indicates improved pressure recovery.

2024, Journal of Engineering Sciences

The article describes the prospects for experimental research of liquid-vapor jet devices with adaptable geometry of the flow part of the primary flow nozzle. To formulate the research objectives, a critical analysis of state-of-the-art studies was conducted among native and foreign scientists studying two-phase jet devices. As a result, of the literature survey, we saw that the working process of the two-phase jet devices, which include liquid-vapor jet devices, is quite complicated to study. So, the achieved results of theoretical studies require clarification and the conduction of additional experimental studies. The article provides a description and experimental research method on the liquid-vapor jet devices with a replaceable diffuser part of the primary flow nozzle. The program and the method contain the range of changing operational parameters while conducting experimental studies. The functional scheme of the experimental scheme and the devices to control and measure press...

2024, Applied Thermal Engineering

h i g h l i g h t s Effects of the ejector geometry parameters on entrainment ratio are investigated. The optimal design is discussed to achieve a high entrainment ratio. The importance of L m /D m is the most in optimization of ejector... more

2024, E3S Web of Conferences

Ejector expansion refrigeration cycle is the modification of the vapour compression refrigeration cycle with the implementation of a two-phase ejector and a vapour-liquid separator to improve the cycle performance. In this study, main geometrical parameters of an ejector, i.e. diameters of the motive nozzle throat, motive nozzle outlet, suction nozzle outlet, and constant area mixing section are calculated in order to provide the preliminary design aspects at various operation conditions. The thermodynamic model of the ejector is established with reference to constant-area mixing assumption. The equations are solved in Matlab®. The environmentally-friendly refrigerants, R1234yf and R1234ze(E) from the hydrofluoroolefins (HFOs) and R134a which is about to be phased out by the F-gas Regulation are used in the analyses. When compared to the previous literature findings, the current research aims to compare the dimensions of a two-phase ejector to be used in an experimental system havin...

2024, Energy

Improvement of the refrigeration cycle performance and the proper design of ejectors for compression energy recovery require a detailed analysis on the internal ejector working characteristics and geometry. To this aim, an experimental and numerical investigation of an ejector refrigeration system (ERS) is conducted to determine the effect of the most important ejector dimensions and main operating conditions on ejector working characteristics and cycle performance. Experimental results show that the best performance of the ejector and consequently the refrigeration cycle were achieved for the maximum pressure ratio at the critical condenser temperature point. At this condition, ejector internal exergy losses are minimal according to the carried out numerical studies. Furthermore, it has been found that the primary nozzle diameter is the most influential factor for ejector performance and pressure ratio improvement. Results show that an increase in the primary diameter leads to the double improvement of the overall ejector efficiency. In addition, it has been found that most of the exergy losses inside the ejector are located in three regions, respectively: the constant area mixing section, the mixing chamber and the primary nozzle.

2024, Kuwait Journal of Science

There has been a large amount of work being conducted on the thermo-dynamics of the Direct Contact Condensation (DCC), however, not much attention was given to the phenomena particularly active near the steam’s nozzle exit. A transparent rectangular upright duct of 4 ft high, was built with a supersonic nozzle positioned at the bottom of the channel to characterize flow behavior near the steam nozzle’s exit. Particle image velocimetry (PIV) was applied to draw information on the steam’s jet penetration into the water as well as the entrainment and mixing between the two phases under the steam’s inlet pressure ranging from 1.5 – 3.0 bars. PIV normalized contour measurements depicted not appreciable changes in the radial velocity of the jet. Whereas, in the core region of the jet, the change in the jet’s velocity was not much till Y/De ~ 4.3 and the vertical velocity of the jet decreased slowly till Y/De ~ 8. The jet’s normalized upward velocity attained an optimized value between Y/D...

2023, Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy

An ejector is a pumping device that uses a high-speed primary fluid jet to entrain a secondary stream. The pumping action is due to the exchange of momentum between the primary and secondary streams. The air ejectors are widely used in mixing systems and many engineering applications. The purpose of the present work is to study experimentally the effects of using different numbers of nozzles with various geometric variables on the performance of the air ejector. The test rig, which is designed particularly for this study, is constructed so that the overall performance of the air ejector can be measured under various operating conditions. To the best knowledge of the authors, there is no published work concerning the study of all the geometric variables with different numbers of nozzles, showing their effect on the ejector performance. The experimental investigations consist of the performance measurements for 52 ejectors. They are classified into three main groups The following conc...

2023

We describe a novel machine that uses the greater-than-100% efficiency of air/ground-source heat pumps to recursively generate electricity via steam-powered generators, taking thermal energy from the ambient environment to convert into electrical power. The invention of a machines that generate clean power at low costs will be fundamental to the future of electricity. We estimate efficiency and calculate minimum efficiencies for unknown parts to consider the applicability of this machine to the real world.

2023, ERJ. Engineering Research Journal

The present work deals with numerical and experimental investigation of supersonic air-air ejectors. The numerical investigation is based on flow equations governing turbulent, compressible, two-dimensional, steady, time averaged and boundary layer equations. These equations are continuity, momentum and energy. In addition, turbulent shear stress and heat transfer are calculated using eddy viscosity model. These equations are solved iteratively using finite difference method under the conditions of different flow regimes which can be divided into several distinctive regions where, the methods for estimating the mixing length are different for each flow region. The first region depicts the wall boundary layer, jet shear layer and secondary and primary potential flow. Tlle second one contains a single region of developing flow. The present results are concerned with the static pressure coefficient, temperature and velocity distributions along the mixing duct and diffuser. Also the overall efficiency of the ejectors for different flow conditions such as, motive air stagnation pressure and temperature, secondary air temperature and mass ratio is calculated. A simple ejector with convergent-divergent primary nozzle was fabricated and experimentally tested. The present theoretical and experimental results are compared with published data. This comparison shows a good agreement. The results obtained help to understand the flow behavior and physical phenomena occurring in the flow through ejectors.

2023, Applied Thermal Engineering

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights • Two novel supersonic nozzles are developed-Tip Ring Supersonic Nozzle and Elliptic Sharp Tipped Shallow (ESTS) Lobed Nozzle, for enhancement of mixing in supersonic jets with minimal loss of stagnation pressure, especially beneficial for application in supersonic ejectors.

2023, International Journal of Materials, Mechanics and Manufacturing

The cooling systems industry is essential in the supply chain of biological products, in the conditioning of spaces for comfort conditions or in industrial processes. This makes it essential for the life of the human being, however, it requires a high demand for energy to operate these systems worldwide, which results in the search for new technology that helps reduce the energy consumption of cooling systems. In this proposal, the operation of an ejector installed in an experimental cooling system is analyzed by CFD. In this study, the ejector is simulated on a two-dimensional geometry, based on experimental results, using R134a as a working fluid and commercial software ANSYS FLUENT 19R1. As a result, the behavior of the velocity vectors was obtained, where there is evidence of recoil in the secondary flow in different operating conditions which leads to an unstable behavior of the experimental system to the imposed operating conditions and an approach in the nozzle outlet primary to the mixing chamber, reduce this behavior.

2023, E3S Web of Conferences

2023

Confined bubble growth during flow boiling at low pressures in microchannels generates pressure fluctuations that may cause transient flow reversals that disturb the flow distribution in heat sinks formed of parallel channels joined by plena. A simple model is developed for the effects of upstream compressibility and flow resistance at the channel inlet on the magnitude of the pressure transient during the growth of one bubble in a single channel. Preliminary results are presented.

2023, ASME 2012 Gas Turbine India Conference

An ejector is a device that entrains a secondary flow into a high speed stream that is generated by expansion of high pressure motive gas [1]. These ejectors can be broadly classified into central ejectors and annular ejectors. A large majority of applications involve central ejectors where the motive gas flow is injected along the centre of the flow passage of the secondary flow. Dutton and Carroll [2] proposed an optimization procedure for such ejectors without taking the mixed supersonic flow region into account and generated the design curves considering the constant Total temperature, Molecular weight and Specific heat ratios. However in some applications involving high temperature gases such as in ramjet/scramjet and gas turbine test facilities, an annular supersonic ejector is more appropriate where annular injection of the motive gas at the periphery of the flow passage is desired to avoid the exposure of the motive gas flow nozzle to the high temperature combustion product ...

2023, International Journal of Refrigeration

We resumed and improved language We have improved the quality of the figures We have reformulated the conclusion We responded to the remarks of referees

2023, Energy

Ejector entrainment ratios are influenced by both pressure-driven effects and the mixing between the primary and secondary streams, but the significance of each factor has not been identified in prior literature. This paper presents a computational simulation investigation of flow in a representative steam ejector to specify the contribution of mixing and pressure-driven effects to the overall ejector entrainment ratio under different operating conditions. The simulation of mixing layer growth was validated by using experimental data available in the literature, while the application of the computational method to the ejector flows was validated using static pressure distribution and entrainment ratio data in the particular experimental ejector arrangement. Simulation results show that under a fixed operating condition for the primary and discharge streams, at lower secondary pressure the ejector entrainment ratio is more strongly influenced by the mixing effects. For the particular ejector and the operating conditions considered herein, about 35% of the ejector entrainment ratio is due to mixing effects when the secondary stream pressure lift ratio is 4.5, while this portion is reduced to about 22% when the secondary stream pressure lift ratio is 1.6.

2023, Energy Conversion and Management

Ejector systems are receiving considerable attention due to their simplicity, lower maintenance requirements, use of low grade heat, longer lifespan and low cost. In this paper an improved model to predict the performance of an ejector refrigeration system under both the critical and subcritical modes of operation was developed and validated. The model predicts ejector performance more precisely compared to studies following the same modelling approach in the literature. Using the developed model, performances with environmentally benign refrigerants, including R1233zd(E), HFO1336mzz(Z), R1234ze(Z), R600, RE245fa2, and RE245fa2 as alternatives to R141b and R245fa were investigated. For ejector area ratios between 4.45 to 12.98, evaporator temperatures between 0 o C and 16 o C and condenser temperatures between 20 and 40 o C, the optimal performance of the ejector system was determined. Results show that for each refrigerant, higher area ratios give higher coefficients of performance, but require higher generator temperatures for better critical condensing temperatures. R600 showed the best performance followed by R1234Ze(Z) and R1233Zd(E) for the entire range of parameters considered. Results further show that there is an optimum generator temperature at each area ratio that maximizes performance. The optimal generator temperature increases as the area ratio and the condensing temperature increase. An alternative and more convenient approach to optimize ejector performance has been suggested in this work.

2023, Energies

The field of computational fluid dynamics has been rekindled by recent researchers to unleash this powerful tool to predict the ejector design, as well as to analyse and improve its performance. In this paper, CFD simulation was conducted to model a 2-D axisymmetric supersonic ejector using NIST real gas model integrated in ANSYS Fluent to probe the physical insight and consistent with accurate solutions. HFOs (1234ze(E) and 1234yf) were used as working fluids for their promising alternatives, low global warming potential (GWP), and adhering to EU Council regulations. The impact of different operating conditions, performance maps, and the Pareto frontier performance approach were investigated. The expansion ratio of both refrigerants has been accomplished in linear relationship using their critical compression ratio within ±0.30% accuracy. The results show that R1234yf achieved reasonably better overall performance than R1234ze(E). Generally, by increasing the primary flow inlet sat...

2023, Applied and Computational Mechanics

Genetic-algorithm methods are used here for single-objective (SO) and multi-objective (MO) geometrical optimizations of jet pumps used in vacuum distillation of ethanol, an application not deeply studied in scientific literature. These devices are particularly suitable to allow the azeotrope-breaking below the atmospheric pressure at ambient temperature. Based on this, different working pressures (Pp), five non-dimensional geometrical parameters that can influence the jet pump operation, and three performance parameters (drag coefficient, pressure recovery ratio and energy efficiency) are considered in this work. Furthermore, using a central composite, face-centered, enhanced experimental design, 89 simulation experiments are run to obtain Response Surfaces (RS) by genetic aggregation, applying afterwards the SOGA and MOGA optimization methods. Also, Spearman Rank-order correlation matrix is employed as initial screening, finding strongly negative correlation of drag coefficient and...

2023, 3rd Shear Flow Conference

2023

Rochester Institute of Technology's Microsystems Engineering & Technology for the Exploration of Outer Regions (METEOR) project has been investigating and pursuing a low cost alternative launch system for launching pico-satellites to Low Earth Orbit (LEO). A major component of this system is a three-stage rocket for orbital insertion. Of all the parts that make up a rocket engine, the nozzle and its ability to convert thermal energy into kinetic energy is the most important in creating an efficient rocket. This paper develops a computer code which uses the Method of Characteristics and the Stream Function to define highefficiency nozzle contours for isentropic, inviscid, irrotational supersonic flows of any working fluid for any user-defined exit Mach number. The contours were compared to theoretical isentropic area ratios for the selected fluid and desired exit Mach number. The accuracy of the nozzle to produce the desired exit Mach number was also checked. The flowfield of the nozzles created by the code were independently checked with the commercial Computational Fluid Dynamics (CFD) code FLUENT. FLUENT predictions were used to verify the isentropic flow assumption and that the working fluid reached the user-defined desired exit Mach number. Good agreement in area ratio and exit Mach number were achieved, verifying that the code is accurate.

2023, Applied Energy

h i g h l i g h t s Steam ejector pump and electric liquid ring vacuum pump are analysed and modelled. A supervised machine learning models by using real process data are applied. The equation of ejector pumped mass flow from steam turbine condenser was solved. The loss of specific energy capable of work in a SEPS or LRVP component was analysed. The economic efficiency analysis per different coal heating values was made.

2023, Experimental and Computational Multiphase Flow

The ability to accurately model condensing flows is crucial for understanding such flows in many applications. Condensing flows of pure steam have been studied extensively in the past, and several droplet growth models have been derived. The rationale for the choice of growth models for condensation in humid air is less established. Furthermore, only a few validation cases for condensation in such flows exist. This paper aims to identify existing limitations of common droplet growth laws. The Hertz—Knudsen model is compared to heat-transfer-based models by Gyarmathy and Young, using an Euler—Lagrange approach in Ansys Fluent. For this, an adaption for Young’s growth law is introduced, allowing its application in condensation of different gas mixtures. The numerical model has been validated and applied to flows in nozzles and turbines in previous publications. The accuracy of the droplet growth models is investigated in transonic nozzle test cases. A case with pure steam and a case w...

2023

In the paper, a one-dimensional compressible flow of gas inside the gas turbine’s diffuser has been simulated. The modeling has been performed to the aim of obtaining boundary conditions of outlet gas from diffuser and inlet gas to the combustion chamber. Depending on working flow regimes of fluid including subsonic, transonic, and supersonic flows, changes of diffuser cross-section have different effects on gas flow characteristics. For these effects to be correctly imposed, Mach number of the gas flow in each time-step affected by changes of cross-section would be determined, depending on the local Mach number in the same time-step. Obtaining distribution of Mach number along diffuser length, changes in other main characteristics of flow such as pressure, temperature, speed, and density for all of the points along diffuser length would be obtained. In order to verify the validity of the numerical algorithm used, the gas flow would be solved in a divergent nozzle and compared to ot...

2023

Numerical investigations have been carried out on water ejector employing water as a working fluid. The effect of nozzle position on its efficiency was investigated. Nozzle position varied the ratio of nozzle-to-throat spacing to throat diameter (X = L/D) with values of 0, 1, 1.5 and 2, respectively. Validation is achieved on selected test cases by the comparison between numerical simulations results and experimental measurements. The numerical results were found in good agreement with the experimental results and the ESDU design guide.

2023, Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy

2023, Applied and Computational Mechanics

2023

The goal of this project was to design and construct a small-scale, supersonic wind tunnel. The wind tunnel was intended to use the difference between atmospheric pressure and the pressure inside the vacuum chamber in WPI\u27s Vacuum Test Facility (VTF) to achieve its desired flow velocities. A previous MQP already designed a small, supersonic wind tunnel, but it was designed for one specific Mach number. As such, it was decided that this project would aim to make a tunnel capable of achieving various test section Mach numbers. The completed wind tunnel was designed for educational and research purposes

2022, Journal of Petroleum Science and Engineering

In order to minimize problems and enhance production, many oil-well applications using jet pumps associated with artificial lift systems have been suggested in the literature. In some scenarios, gas from the annulus can be beneficially compressed by using oil-well´s production as power fluid. Because multiphase fluids are generally produced, understanding and modeling multiphase jet pumps for gas compression (MJPG) is essential for design applications. Considering homogeneous multiphase flow, a simplified model is proposed and analytical solutions are presented in this article. A detailed analysis of the proposed model is performed and its physical consequences are discussed. Very good agreement between the proposed model and the conducted 3D numerical simulations (Ansys CFX 16.0) was observed. Furthermore, in agreement with experimental results reported in the literature, the numerical results showed that the MJPG is highly influenced by mixing process in the throat. Finally, the numerical simulations showed that slippage hinders complete mixing in the throat and reduces pump's efficiency.

2022, Analele Universităţii "Constantin Brâncuşi" din Târgu Jiu: Seria Inginerie

Gas/vapor ejectors are widely used in various applications due to significant advantages over other devices used to raise the momentum of a gas. The main application of ejectors is pumping (increasing pressure) of a low pressure fluid by taking advantage of the depression caused by expansion of a high pressure fluid – motive fluid. Low energy efficiency of the process is the main disadvantage of the ejector technology. The geometry of the device, fluid thermo-physical properties and parameters influence the efficiency of the entrainment process. The ejector consists of three main parts, primary nozzle, mixing chamber and diffuser. Although a simple device, the flow in an ejector system is complex and difficult to model in some respects. Supersonic flow in ejectors resulting from expansion of the motive fluid in the nozzle creates the chocking condition that limits the maximum value of the entrained flow. The paper explores by means of CFD a non-conventional ejector geometry which ca...

2022, Transactions of the VSB : Technical University of Ostrava

The article deals with design and numerical calculation of a variable test section for small supersonic wind tunnel. The supersonic wind tunnel is designed to be driven by a supersonic ejector. The test section, which is in focus, is considered to by placed on its suction inlet. Schlieren method will be used to investigate the flow within. The purpose of the test section is to demonstrate effects, which occur in supersonic flows, e.g. shock waves, interactions of shock waves with boundary layers etc. Proper demonstration of such phenomenon requires different conditions gained within test section. Internal parts of the device are designed to be interchangeable or variable to provide this capability. The work deals with investigation and design of construction of the variable test section. Consequently, shape of the supersonic inlet nozzles for chosen Mach numbers are carried out. Methods of characteristics and CFD are employed to manage this task. The construction of the test section...

2022

In this study, an optimization of supersonic air-to-air ejector is carried out by a recently developed single-objective genetic algorithm based on adaption of sequence of individuals. Adaptation of sequence is based on Shape-based distance of individuals and embedded micro-genetic algorithm. The optimal sequence found defines the succession of CFD-aimed objective calculation within each generation of regular micro-genetic algorithm. A spring-based deformation mutates the computational grid starting the initial individualvia adapted population in the optimized sequence. Selection of a generation initial individual is knowledge-based. A direct comparison of the newly defined and standard micro-genetic algorithm is carried out for supersonic air-to-air ejector. The only objective is to minimize the loose of total stagnation pressure in the ejector. The result is that sequence-adopted micro-genetic algorithm can provide comparative results to standard algorithm but in significantly lowe...

2022, Volume 1

This paper deals with design and analysis of intermittent supersonic wind tunnels. System can be constructed by allowing air at atmospheric pressure to pass through a converging-diverging nozzle, a test section and a diffuser into a vacuum tank. The governing equations of compressible fluid flow have been solved numerically using flux vector splitting method to obtain running time under which it works at the design Mach number. The formulation has been tested on the theory of quasi one-dimensional compressible flow. The numerical results are in good agreement with the results of the theory.

2022, Experimental Thermal and Fluid Science

1The Euler-Lagrange equation was used to minimize shear stress in designing a flow-metering nozzle. The flow field in the nozzle was computed by solving the momentum equation in integral form. The profile of the nozzle was obtained by minimizing the shear losses in the converging section of the nozzle. Following computation of the profile, a metering nozzle was designed, constructed, and subsequently tested to evaluate the validity of the analysis. The nozzle was designed for a pipe diameter of 15.24 cm (6 in.) and a throat diameter of 9.266 cm (3.648 in.). The test results indicated a marked increase in the value of the discharge coefficient when it is compared with that for the ASME standard nozzle. The computed pressure distribution is in good agreement with the experimental data.

2022, Kuwait Journal of Science

2022

The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

2022

Effects of deceleration and mean compression on the turbulence structure of supersonic flow in a diffuser with an incoming supersonic fully-developed turbulent pipe flow are studied by means of DNS. Strong enhancement of the turbulence activity is observed when the flow undergoes deceleration. Turbulence production and pressure-strain terms in the Reynolds stress budgets are found to increase dramatically leading to increased Reynolds stresses. The central role of pressure-strain correlations in modifying the turbulence structure under these flow conditions is demonstrated.

2022

E xperience during the execution of engineering design and consultancy services has shown that the commonly available process simulation software is not applicable for many gas/gas ejector applications encountered. Gas ejector design can however be determined by rigorous calculation using the applicable equations [1, 2]. A study was performed to establish a simpler methodology for ejector design and for the prediction of performance, based on the following: • published results by manufacturers; • literature survey; • published empirical results; • experience from design projects. A thermodynamic spreadsheet model was prepared based on equations [1, 2]. Results were analyzed and compared with published results and with the simulation results obtained by using cfd codes (as UNISIM and HYSIS). Findings are presented herein, together with a recommended simplified method for the prediction of ejector performance.

2022

This paper describes the flow dynamics inside a supersonic ejector using CFD modelling. Suitable ejector geometry is proposed for the high compression ratios encountered in real world applications. Post-processing and physical analysis of the CFD results are presented to better understand the entrainment mechanism and the mixing between the primary and the secondary fluids. The effect of the primary pressure on the flow dynamics and the entrainment ratio is discussed for the two compression ratios of 1.67 and 3.4.

2022

2021, International Journal of Heat and Technology

Supersonic ejectors can be used in heat powered chillers to transfer mechanical energy between the motive and the inverse cycle. Within the ejector, momentum is exchanged between a high speed flow produced by a primary nozzle and a slow current coming from the chiller evaporator. Due to the supersonic regime of the primary flow, the mixing of the two streams causes significant loss and impairs the system efficiency. Up to now, second law efficiency of ejector chillers is quite low and optimization is highly needed. The fluid dynamics of the whole ejector involves turbulent mixing, shock trains and complex wall flow, requiring CFD analyses for an adequate description. However, in order to attempt an optimization, mathematically workable models are advantageous. An analytical scheme that captures the basic features of the turbulent mixing zone is discussed here in view of a Constructal design of an ejector chiller.

2021

Simulation model of converging-diverging (CD) nozzle to improve particle delivery system of deoxyribonucleic acid (DNA)

2021

Through this study, an endeavour has been taken to emphasize on the need of the management information systems (MIS) in Jamuna Fertilizer Company Limited (JFCL), especially to identify the potential areas wherein the MIS could be effectively used. Management information system (MIS) or computer information system (CIS) consists of five related components: hardware, software, people, procedure, and collections of data. The term information technology (IT) represents the various types of hardware and software used in information systems, including computer and networking equipments. There is some lacking in business solving networking system like MIS/CIS/IT in the JFCL. Main barriers are a lack of leadership, motivation and shortage of skill manpower to implement MIS in JFCL.