Ejector System Research Articles

Drill bit hydraulic system for oil and gas boreholes

We set out to improve the existing design of a polycrystalline diamond bit with a steel or matrix body with the purpose of creating a hydro-monitoring effect. The research object was the hydraulic system of a diamond bit with a near-bit jet pump. The near-bit ejector system was studied by a theoretical analysis of the operation of the bit hydraulic system by means of canonical dependencies and hypotheses. A hydraulic system for a polycrystalline diamond bit is proposed. This system includes a high-pressure jet pump, which enhances the hydro-monitoring effect at the bottomhole. The main hydraulic characteristics of the bit flushing system with a jet pump are as follows: at a drilling pump feed of 18.4 l/s and a drilling fluid density of 1180 kg/m3, the working coefficient of jet pump injection equals 0.34; the working nozzle diameter equals 10.3 mm; the mixing chamber is 11.9 mm, bit hydromonitor nozzles are 11.1 mm; the number of hydromonitor nozzles is 3; the velocity at the exit of hydromonitor nozzles is 85.0 m/s; the pressure drop at the bit is 15.7 MPa. The possibility of using the hydro-monitoring effect enhanced by a near-bit jet pump was substantiated, since the velocity at the exit from the hydro-monitoring nozzles is sufficient to destroy most rocks (sandstone, limestone, dolomites, rock salt, gypsum stone, basalt, marble, granite). The jet pump in the proposed design of a polycrystalline diamond bit creates an additional circulation circuit above the bottomhole, injects cuttings from the annular space and feeds them to the hydro-monitor nozzles. This enables a more efficient destruction of the bottomhole rock. The power of hydro-monitor jets is sufficient to improve drilling performance.

A novel tether-net configuration with double-linked bullets for suppressing reshrinking motion after full deployment

Tether-nets have attracted considerable attention as tools for capturing space debris. However, owing to the lack of aerodynamic drag to resist collapse in space, tether-nets tend to shrink back after deployment because of tension. Various strategies have been proposed to suppress this reshrinking motion before debris capture, such as equipping bullets with thruster modules to control their trajectory after ejection and incorporating a bullet ejection-angle adjustment mechanism. However, these approaches complicate the tether-net design and/or ejection systems. In this study, a novel tether-net configuration comprising double-linked bullets, wherein the inner and outer bullets are connected via a tether, was proposed to prevent the tether-net from reshrinking after full deployment. Upon full deployment, as the bullets start to rebound from impulsive tension, the outer bullets fly outward, pulling the inner bullets and exchanging momentum to suppress their rebounding motion. The effectiveness of the double-linked bullets in suppressing the reshrinking motion of the tether-net was demonstrated by comparing the results with those obtained using typical single-linked bullets. Furthermore, the influence of the inner and outer bullet mass ratio on the tether-net deployment and reshrinking motion was numerically analyzed to identify the optimal mass ratio for effectively suppressing the reshrinking motion. The results indicate that a mass ratio of 1.0, or slightly less, between the outer and inner bullets is most effective in suppressing tether-net reshrinking.

Numerical and experimental study on effects of net-bullet ejection angles and initial distances on space-debris capture

The increasing volume of space debris in the outer space poses a significant threat to operational spacecraft. Hence, net capture systems have emerged as a promising technique for removing space debris. These systems operate by deploying a net to envelop and capture the debris. The effectiveness of debris capture using nets depends on ejection parameters such as speed, ejection angle, and the crucial initial distance between the net and debris. Simulations are performed to examine various scenarios of active debris removal. In addition, the experiments involved meticulously calibrated net and debris ejector systems, where bullets are utilized for net deployment by varying the angle of bullet ejection (θ). The net trajectory is determined using simplified equations of motion, while considering both the ejection dynamics and its interaction with the debris. The findings of this study reveal the correlations between the initial parameters and net performance pertaining to space debris capture. Larger ejection angles and greater distances between the net and the debris-hindered debris capture. Despite slight simultaneous net and debris ejection delays, the results of the real-world experiments validated the simulation results.

Comparative Study of Pumping Performance of Fluidyne Pump with Ejector and Centrifugal Solar Pumping Systems

Comparative Study of Pumping Performance of Fluidyne Pump with Ejector and Centrifugal Solar Pumping Systems

Mathematical model of a three-stage vacuum ejector system

Mathematical model of a three-stage vacuum ejector system

Optimizing sorbitol double dehydration: A Box-Behnken design approach with commercial sulfonic acid resin

In this study, double dehydration of sorbitol into isosorbide using commercial sulfonic acid resin as a catalyst was carried out under vacuum conditions generated by water ejection. To improve the efficiency and selectivity of the process, optimum reaction conditions prescribed by temperature, catalyst loading, and reaction time were investigated using the Box-Behnken design (BBD) together with Response Surface Methodology (RSM). The results showed that using the water ejection system could increase reaction activity. Statistically, all the reaction parameters were found to significantly affect the double dehydration reaction response, including sorbitol conversion, 1,4-sorbitant yield, and isosorbide yield. Furthermore, accurate predictive equations for all the reaction responses displayed R2 > 95 %, with no significant errors observed. The optimized conditions resulted in the complete conversion of sorbitol with 6.42 % 1,4-sorbitant yield and 67.55 % isosorbide yield. The equations yielded predicted values of the responses with minor variances being lower than 1 % when compared with the experimental values. However, the efficiency of the catalyst decreased steadily over recycling cycle due to reduced active sites and textural properties, likely caused by structural collapse and by-product accumulation. This work contributes to biomass valorization by optimizing the effective process for the production of isosorbide via commercial catalysts under vacuum conditions.

Design of a washing ejector and column flotation based on the microbubble for heavy metal contaminants removal from contaminated soils: A pilot and laboratory-scale studies

This study mainly examines the effects of combined washing ejector and column flotation process by remediation equipment for heavy metal remediation at a contaminated site. A washing ejector system is a sustainable technology that considers the concept of hydrodynamic cavitation. Soil aggregates strongly binding to poorly crystalline minerals and Fe oxide bonding with the soil create challenges for their elimination from soils contaminated with complex contaminants. The effects of the operating conditions of the cavitation flow on increasing the separation of fine particles were evaluated by determining the mass balance during the washing system process on a pilot scale. Cavitation flow in the washing ejector system can increase the dispersion of soil aggregates owing to the generation of hydroxyl radicals (•OH) and the increase in mixing intensity. Cavitation flow during the process can increased the dispersion of soil aggregates owing to the release of Fe oxides into the soil. The coarse and fine particles were readily separated from the bulk soil, and the fine particle distribution per mass increased after washing. The levels of Fe in the coarse fraction soil met the KS requirements after separation, whereas the Fe levels in the fine fraction soil were above than the KS limits. To reduce waste volume, column flotation was used to selectively separate Fe oxides from contaminated soil. Microbubbles in column flotation have the important function of facilitating the collision and attachment between air bubbles and Fe oxides and subsequently recovering the Fe oxides. When AF65 as a frother and oleic acid as an anionic collector were used in the column flotation, the concentration of Fe oxides increased from 9.67 % to 13.76 %, a recovery of approximately 10 % from the fine soil. According to the mass balance of the study area, after treatment using the washing ejector system, coarse (60 %) and fine (40 %) soils in the total soil were separated. Column flotation can be applied to fine soil to achieve a volume reduction of approximately 30 % of the total soil volume. The results of this study illustrate the feasibility of the proposed remediation process to reduce waste volume and improve sustainability while meeting Korean standards for heavy metal pollution in soil, thereby minimizing environmental risk.

Thermodynamic modeling and performance optimization of transcritical CO2 dual-evaporator refrigeration system enhanced with ejectors

The utilization of ejectors in transcritical CO2 refrigeration systems is known to enhance system performance significantly. However, the operational conditions play a crucial role in determining the system’s overall efficiency. This study introduces a thermodynamic model for transcritical CO2 ejector refrigeration systems and investigates the influence of operating conditions on system performance for four different refrigeration systems, and the optimization of the Nakagawa sound velocity model coefficient in the ejector modeling is carried out to enhance the accuracy of the model. Meanwhile, these research contents are also the innovation of the research. Key conclusions include: (1) Increasing the Nakagawa coefficient to 1.1 improves model accuracy. (2) Ejector inclusion enhances system COP, with one configuration showing a 43.36 % increase and another a 53.23 % increase, recommending different system setups for large spaces like supermarkets and smaller areas like refrigerated vehicles. (3) Higher evaporating pressures result in better COP for ejector systems, with a suggested maximum air cooler pressure of 9 MPa. COP also benefits from increased ejector outlet pressures. (4) AR (area ratio) of the ejector affects mass flow rates and cooling capacity significantly, while its impact on COP is minimal. Adjusting the primary throat area can control cooling capacity for varied needs. The study provides actionable insights for improving the design and efficiency of transcritical CO2 ejector refrigeration systems.

МОДЕЛЮВАННЯ РОБОЧОГО ПРОЦЕСУ СТРУМИННОГО НАСОСА ПРИ ЙОГО АСИМЕТРИЧНОМУ ОБЕРТАННІ В СВЕРДЛОВИНІ

The structure of the equations of the pressure-flow characteristics of the high-pressure jet pump is supplemented with a component that determines the additional pressure caused by the influence of eddy currents during the asymmetric rotation of the ejection system around the axis of the well. On the basis of the joint solution of the Bernoulli equations, the preservation of the integrity of the moving medium, the momentum and moment of movement of the mixed flows, a relationship was obtained for the analytical determination of the additional dynamic pressure created by the rotation of an eccentrically placed jet pump in the well. In the process of researching the resulting equation, the extreme nature of the growth of the pressure-flow and energy characteristics of the overbite ejection system was established. The increase in pressure and efficiency caused by the asymmetric rotation of the over-chisel ejection system is inversely proportional to the value of the main geometric parameter of the jet pump.

Reducing the level of infrared radiation of a ground vehicle during its movement

Problem. Reducing the visibility of a ground vehicle makes it possible to increase its survivability and provide conditions for the performance of assigned tasks. The development of approaches to the analysis of the conditions for the formation of a heat trace from the engine of the ground vehicle is an extremely important scientific and practical task. Goal. The purpose of the work was to carry out comparative numerical modelling to assess the effectiveness of diluting the EG flow of the engine of the ground vehicle with atmospheric air to reduce their temperature. Methodology. Using the method of finite volumes, a comparative numerical experiment was conducted in a three-dimensional stationary setup. The possibility of sucking atmospheric air with the standard nozzle of the ejector was quantified. Results. The study shows that the addition of atmospheric air can effectively reduce the temperature of exhaust gases. The use of a regular ejection system allows to reduce the temperature of exhaust gases by 10-12 degrees without additional energy consumption. Originality. Using the method of a comparative numerical experiment, the effectiveness of adding atmospheric air to the exhaust gases of a diesel engine in order to suppress the heat trace was evaluated. Practical value. An approach to reducing the temperature of the exhaust gases of the ground vehicle engine is proposed, that allows to decrease its visibility in the infrared radiation spectrum without additional energy consumption.

Comparative evaluation of experimental ejector refrigeration system for different operating configurations

In this study, a comparative performance evaluation of an experimental ejector refrigeration system was conducted for various operating modes. The experimental setup was operated in different modes: conventional vapour compression refrigeration (CVCR), conventional dual-evaporator system (CDES), and dual-evaporator ejector system (DEES). The system was tested under different operating conditions, including varying condenser temperatures and mass flow rates. The results of the evaluation showed that the highest total cooling capacity and coefficient of performance (COP) were achieved in the DEES mode, while the lowest total cooling capacity was observed in the CDES mode. The lowest compressor power was calculated when the system was operated in DEES mode. When the condenser temperature was 33°C, the compressor power obtained in the DEES was 22.7%, 5.4%, and 17.7% lower than that of the CVCRA, CVCRB, and CDES modes, respectively. In conclusion, the performance of the ejector-operated system was found to be superior to the other configurations, and the ejector contributed positively to the system performance.

Numerical Simulation on Two-Phase Ejector with Non-Condensable Gas

The two-phase ejector is a simple and compact pressure boosting device and widely used in ejector steam-generator water feeding systems and core emergency cooling systems. The direct contact condensation of water and steam is the key process of a two-phase ejector. Usually, the high-temperature and high-pressure steam will inevitably induce non-condensable gases. The existence of non-condensable gases will reduce the condensation heat transfer rate between steam and water, and harm the equipment. This study carried out 3D numerical simulations of a two-phase ejector based on an inhomogeneous multiphase model. The steam inlet pressure and the non-condensable gas mass fraction rang in 0.6–2.9 MPa and 1–10%, respectively. The heat and mass transfer characteristics were analyzed under different conditions. The results show that the heat transfer coefficient and plume penetration length increased with the steam inlet pressure. Non-condensable gas prevents direct contact condensation between the steam and water. The non-condensable gas mass fraction rises from 1% to 10%, the heat transfer between steam and water deteriorates, and leads to a lower heat transfer coefficient.

Model matematyczny procesu pracy układu wyrzutowego podczas obrotu pompy strumieniowej w otworze

A mathematical model of an above-bit jet pump has been developed for the conditions of its rotation in a well, based on the use of hydrodynamic functions of a complex variable. These functions take the form of a sum of partial solutions of differential equations describing the potential motion of radial, circulation and homogeneous flows. The working flow is considered as a leak for a stationary jet pump or as a vortex in the case of rotation. The injected flow corresponds to a homogeneous one. The mixed flow is assessed in accordance with the principle of superposition by summing the complex potentials of elementary flows. The complex potential of the total flow determines the velocity field in the mixing chamber of the jet pump and allows us to set the configuration of the zero flow line, which separates the working and injected flows. In the process of integrating the velocity profile, the coefficient of uneven distribution of kinematic parameters is assessed, the value of which is included in the structure of the equation for the pressure characteristic of the jet pump and determines the effect of circulation flows on the working process of the ejection system. It has been established that the maximum velocity of the symmetrical rotation of the jet pump in the well increases the generated pressure and efficiency by 7.79% and 9.57%, respectively. Using the experimental head characteristic of the jet pump, obtained for the case of simultaneous swirling of the working and injected flows by the guide elements, the value of the relative head corresponding to the same rotation velocity of the mixed media has been assessed. The investigated values of the relative head pressure are used to verify the adequacy of the developed mathematical model of the ejection system for the rotation of the jet pump in the well. The maximum discrepancy between the theoretical and experimental values of the relative head pressure of the jet pump is 3.64%.

Biodentine™ as a temporary filling in deep carious lesions in permanent teeth: a prospective observational 33-month follow-up study.

The study aimed to evaluate temporary fillings using Biodentine™ in asymptomatic deep carious lesions after 12, 24, and 36months in school children from the remote village of Kerung, Nepal. From November 2018 to November 2019, 91 temporary fillings were placed using Biodentine™ (a hydraulic calcium silicate cement) in permanent molars with deep carious lesions of schoolchildren in the remote district of Kerung, Nepal. These restorations were performed after selective caries removal in a non-dental setting with hand instruments and cotton roll isolation, as electric motors and saliva ejection systems were unavailable. In total, 78 single-surface and 13 multi-surface fillings were placed. Clinical and radiographic follow-up periods encompassed 12, 21, and 33months, respectively. After 12months, all single-surface fillings (100%) survived, whilst all multi-surface fillings were partially or entirely lost. The survival rate of single-surface restorations after 21 and 33months was 67.6% and 50%, respectively. Radiographically, no pathology was observed. This study showed that Biodentine could be used in deep carious lesions as a temporary filling in single-surface lesions for at least up to 1year and in a substantial number of cases for up to 21 and 33months.

Simultaneous optimization of crude oil refinery vacuum distillation column and corresponding ejector system

A vacuum distillation unit (VDU) is a relatively complex crude oil refining process that usually overlooked in researches. A detailed review of the corresponding literature reveals that most of the limited existing researches focus on either the study of the vacuum tower alone or its vacuum creating ejector system. For the first time, the combination of VDU tower and corresponding ejectors are studied in this article by resorting to coupling of Aspen-HYSYS simulation software with Ansys-FLUENT computational fluid dynamic. Both simulations were initially validated by using two sets of experimental and industrial data, borrowed from literature.Optimization of an industrial unit improved its process economics by boosting the heavy vacuum gasoil production around 38% and reducing the less valuable cut of vacuum residue by 28%, which increases the overall earnings of the optimal VDU column economics over 140 MM$/year. Furthermore, sensitivity analysis of the VDU ejector system revealed that the primary steam cost does not depend on the corresponding temperature, while, it rapidly rises, when the motive fluid pressure increases. The overall simulation results of the VDU tower and corresponding ejector system concluded that the lower primary steam pressures are more favorable both from operational and economical standpoints.

A COMBINED DESALINATION AND REFRIGERATION SYSTEM BASED ON SOLAR EJECTOR TECHNOLOGY

A solar ejector technology-based system that combines refrigeration and desalination was investigated for the present study. The proposed model combined a conventional ejector refrigeration system with a desalination unit to examine its ability to achieve cooling as well as produce clean water. An analytical model of the ejector was developed using 1D compressible flow equations based on mass, momentum, and energy conservation. The output from the ejector was then fed to a 1D heat exchanger model to compute the clean water production. The analytical model was implemented using the Matlab platform. A 2D axisymmetric numerical simulation of the ejector system was also performed to comprehend the internal flow structures. It has been observed that the entrainment ratio, which is the ratio of the vapor refrigerant's mass flow rate to the motive steam's mass flow rate, falls as the stagnation temperature of the motive steam increases. It was noted that the coefficient of performance (COP) rises as the evaporator temperature rises, but it is seen to decline with the rise in generator temperature. The amount of desalinated water that can be produced with the system was also explored. It was observed that the production of desalinated water increased proportionally with the rise in generator temperature. At a generator temperature of 140°C, the system obtained clean water at a rate of about 2.9 g/s, which corresponds to a 24.5% mass flow rate of the input steam.

АНАЛИЗ РАБОТЫ ДВУХСТУПЕНЧАТОЙ ГИДРОЭЖЕКТОРНОЙ ВАКУУМСОЗДАЮЩЕЙ СИСТЕМЫ, ОПРЕДЕЛЕНИЕ ЕЕ ОПТИМАЛЬНЫХ ТЕХНОЛОГИЧЕСКИХ ПАРАМЕТРОВ

The article considers the features of the operation of hydro-ejector vacuum-generating systems. The diagram of a two-stage hydro- ejector vacuum-generating system is described, and a calculation algorithm is given. The dependence of the yield of the components of the vapour-gas mixture on the temperature of the working fluid was analyzed, and the required heating temperature of the working fluid was determined. A calculation of a two-stage hydraulic ejector vacuum-creating system was made, and the dependence of the flow rate of the working fluid on the pressure and power consumption of the pumps was determined.

Quasi One-Dimensional characteristic analysis of ejector nozzle for turbofan propulsion system

To investigate the impact of the ejector characteristics of the exhaust system on the overall performance of a turbofan engine, this paper presents a study on the overall performance of the turbofan engine equipped with an ejector nozzle, focusing on its characteristics. Firstly, the design of the ejector exhaust system is presented and its ejector characteristics are analyzed through two-dimensional computational fluid dynamics simulations. Subsequently, a one-dimensional theoretical analysis of the ejector is conducted, and the pump suction and ejector nozzle’s thrust characteristics are determined based on the analysis results. Furthermore, a two-dimensional interpolation method is proposed to calculate the ejector coefficient, which utilizes the ejector's pump suction characteristics. By applying the matching principle of the ejector coefficient, a component-level model of the turbofan engine with an ejector nozzle is established. Based on this model, a method for predicting the backward infrared radiation intensity of the ejector exhaust system is proposed to investigate the influence of the ejector nozzle characteristics on the overall engine performance and infrared signature. The results demonstrate that the installation of the ejector exhaust system leads to a slight decrease in the overall engine performance, in which the average decrease of thrust is about 1.5%, and the average increase in fuel consumption is about 0.5%.but significantly reduces the infrared stealth characteristics, the average reduction is about 20%, which has good infrared stealth effect.

Experimental analysis of the air-to-water ejector-based R290 heat pump system for domestic application

The aim of this study was to analyze and compare the performance of an 8 kW ejector-based R290 heat pump system for hot water heating applications that operates with two different expansion devices: a throttling valve and a two-phase ejector. The vapor compression system was designed to compare the unit operating in direct expansion and ejector-based working modes under similar operating conditions. The test results were assessed for overall system performance measured by COP and heating capacity and for single-component operation. The ejector mode allowed operation at the same range of ambient temperatures as direct expansion mode with the potential to completely replace the expansion valve. The COP of ejector system was up to 2.6, which was 38% higher than direct expansion when working under similar conditions for an ambient temperature of −12.8°C. Moreover, the COP in direct expansion mode decreased significantly along the decrease of ambient temperature, whereas for the ejector mode this decrease was considerably smaller.

Numerical investigation of the effects of dry gas model and wet steam model in solar-driven refrigeration ejector system

Abstract Nowadays, the use of equipment with little pollution is essential due to the increase in the planet’s temperature. Ejectors are considered one of the equipment with no pollution, and their failure rate is low due to the lack of moving parts. Also, scholars have recently focused on improving the efficiency of industrial equipment. The use of accurate modeling is required to improve steam ejector performance. In a steam ejector, non-equilibrium condensation creates a two-phase flow situation. The wet steam model, used in this study, characterizes this two-phase flow. The study’s objective was to compare this wet steam model with the dry gas model. In the wet steam model, the liquid mass fraction is 0.25, and its calculated entrainment ratio is lower than the dry gas model, closely matching experimental observations. The dry gas model reaches a maximum Mach number of about 5, while the wet steam model approximates 4. A significant temperature difference exists between the two models, with the dry gas model indicating lower temperatures compared to the wet steam model. Diagonal shocks and expansion waves are evident in the mixing chamber, fixed cross-section, and diffuser. These phenomena occur with greater intensity and a slight delay in the wet steam model compared to the dry gas model.