Gas Ejector Research Articles

Numerical study of the influence of structural parameters on the performance of annular ejector

Abstract Compared with the central ejector, the annular ejector is widely used in refrigeration, coal mining and chemical industry because the working fluid enters the suction chamber through the annular nozzle, the contact area with the ejection fluid increases, and the ejection fluid does not need to change the flow direction. In order to solve the problem of low performance of annular gas ejector, this paper designs an annular gas ejector with reference to the relevant model, and the axial length and suction angle of the mixing tube of the annular gas ejector are mainly studied. The results show that there is an optimal value for the length of the ring gas ejector mixing tube, and the length of the mixing tube is too long or too short is not conducive to the gas extraction of the ring gas ejector. Under the same annular gap, with the increase of the jet angle, the amount of gas consumed in the primary stream does not change much, and the gas to be pumped decreases, resulting in the performance of the annular gas ejector being reduced, which is not conducive to the suction of the ejector.

Experimental analysis of the R290 variable geometry ejector with a spindle

The aim of this work was to experimentally analyze the variable geometry gas ejector with a spindle designed for operation with the natural working fluid propane (R290). The performance of the ejector was evaluated based on the mass entrainment ratio and critical temperature, being the most crucial parameters for optimizing the cooling capacity in ejector refrigeration systems, as well as the ejector efficiency using common literature notation. Additionally, local pressure drop measurements allowed for the determination of pressure profiles inside for different spindle positions used for capacity regulation. The experimentally defined ejector efficiency curves demonstrated the ability to control the ejector capacity by means of the spindle, irrespective of the unfavorable operating conditions. By decreasing the effective throat area using spindle, the ejector mass entertainment ratio increased by 35%. Spindle movement allowed for the decrease of the motive nozzle flow rate by up to 65%, while still maintaining the suction of the secondary flow of the ejector. Moreover, the behavior of a slight increase in suction nozzle flow with a decrease in motive nozzle flow has been observed for the initial movement of the spindle followed by a huge drop for further reduction of the effective throat area, confirming the previous conclusions shown in the literature.

Microfluidic Engineering of Addressable Multicompartmental Microspheres for Multicellular Systems.

With the advantages of high-throughput manufacturing and customizability, on-microsphere construction of in vitro multicellular analytical systems has garnered significant attention. However, achieving a precise, biocompatible cell arrangement and spatial signal analysis in hydrogel microspheres remains challenging. In this work, a microfluidic method is reported for the biocompatible generation of addressable supersegmented multicompartmental microspheres. Additionally, these microspheres are developed as novel label-free multicellular systems. In the microfluidic approach, controllable microfluidics is used to finely tune the internal microstructure of the microspheres, and the gas ejector ensures the biocompatibility of the preparation process. As a proof of concept, six- and twenty-compartment microspheres were obtained without the addition of any biohazardous reagents. For microsphere decoding, the visualization of two basic compartments can provide clues for identifying label-free cells due to the structural regularity of the microspheres. Finally, by encapsulating cells of different types, these microspheres as multicellular systems were successfully used for cell coculture and drug testing. These biocompatible, scalable, and analyzable microspheres will open up new prospects for biomedical analysis.

Thermodynamic analysis of an enhanced ejector vapor injection refrigeration cycle for CO2 transcritical operation at low evaporating temperatures

The main drawback associated with CO2 refrigeration systems is related to their performance reduction during transcritical operation at warm climate conditions, which may be compensated by better cycle architectures such as the split-cycle with subcooling or the flash-tank configuration, among others. Specifically, the use of standard gas-ejectors together with parallel compressors provides even better efficiency improvements, not being able to use them with low-temperature evaporators to prevent the triple point inside the ejector. This paper proposes an enhanced cycle with a gas ejector for two-stage compressor architectures with vapor injection from the flash-tank, which is able to operate at low evaporating temperatures and that provides a greater performance improvement the more severe the climate conditions are. The methodology conducted is based on a thermodynamic analysis that includes parametric evaluation and cycle optimization, comparing the results to a conventional CO2 transcritical cycle with flash-tank and dynamic vapor injection architecture. The main results show that a maximum Coefficient of Performance improvement of 17.5% is achievable for transcritical operation at -40 °C evaporating temperature. The compressor displacement capacity required with the enhanced cycle is up to 9% lower for the same refrigeration demand, reducing the electrical consumption as well as the compressor expenditure. Moreover, greater vapor injection mass flow rates are obtained by the gas-ejector injection with discharge temperature reductions up to 18%, enhancing the system reliability.

The case study of the surface roughness influence at additively manufactured ejector and orifice plate and its impact on fluid flow

ABSTRACT Energy consumption and economic growth are strongly linked. In connection, great emphasis is nowadays placed on the accuracy and efficiency of machines and measuring equipment. This study compares the effect of surface roughness on airflow through a gas ejector and a centric orifice plate. Both devices are made from the same material but using two different methods of manufacturing, conventional and additive manufacturing. The study compares, experimentally and with numerical simulation, the subcritical ejector by adjusting the distance between the nozzle outlet and the mixing chamber outlet in the range of 16.9 mm, during the primary inlet pressure control from 10 to 50 kPa. The orifice is evaluated experimentally for different pressures from 0.6 to 7 bar(g). The study evaluates the level of substitutability of conventionally manufactured devices by those produced using the additive method. At design condition, the additively manufactured ejector exhibits a 12.97% lower ejection coefficient, i.e. lower effectivity. After control optimization, the decrease is reduced to 11.66%. For the additively manufactured orifice, the measured value of the pressure difference at nominal parameters deviated by 2.17%. In the case of the orifice, substitution is possible, assuming the calibration, but the orifice has a higher-pressure loss.

Condensation shock topologies in carbon dioxide and a non-condensable gas mixture in supersonic nozzles

Condensation shock waves may occur in many flow expansion devices such as turbomachinery, gas ejectors, micro thrust-nozzles, and supersonic gas flow separators. However, their experimental analysis has been barely addressed as condensation shocks comprise complex phenomena such as compressible flow behavior, a shock-like phase transition, and a two-phase flow expansion. This work characterizes experimentally some condensation shock topologies of a mixture of carbon dioxide and dry air at several compositions in a Laval nozzle. Experiments were carried out in a test-rig instrumented with high-response pressure transducers installed along the Laval nozzle wall along with a Schlieren setup equipped with a high-speed video camera imaging the flow behavior within the nozzle. The nozzle wall profile was built by using the method of characteristics developed from a real equation-of-state suited for the testing mixture. Results revealed the influence of the nozzle wall profile on the condensation shock location and topology. Moreover, there types of flow behavior were captured and named as conventional, transition, and Mach wave condensation shocks. The transition from one topology to another occurred due to the interaction between cancelation waves originated from the nozzle wall and the phase-change phenomenon, giving rise to two distinct regions characterized by certain observable droplet population density. The current investigation presents an in-depth phenomenological discussion of the three types of condensation shock topologies as such assessment has not been previously developed.

Flow Channel Optimization to Improve the Performance of a Liquid–Gas Ejector for an Intelligent Toilet Spray Bar

Intelligent toilets can effectively remove odors and harmful substances from exhaust gases and wastewater, maintaining a fresh and clean indoor atmosphere, which is beneficial to the indoor environment and human health. Currently, research on intelligent toilets conducted by sanitary ware manufacturers is still in its early stages. Many of the intelligent toilets available on the market exhibit issues such as an excessive oscillation amplitude of the cleaning spray bar, premature breakdown of the water column, and inadequate air intake. The present study involves the analysis and redesign of a cleaning spray bar model for intelligent toilets. Additionally, several optimization schemes concerning the flow channel of the cleaning spray bar are proposed in order to enhance the performance of the liquid–air ejector. The computational fluid dynamics (CFD) technique is utilized to analyze the water flow characteristics within the cleaning spray bar of the intelligent toilet and to compare and evaluate the proposed schemes. The calculation results indicate that, for the same inlet flow rate, the optimal structure the block with a length of L = 1.5 mm and the block positioned (4). The swirl numbers of these two optimized models are 14.8% and 8.3% of the protype, respectively, while their air intake is 133% and 131% of the protype, respectively. The optimized solutions exhibited significant performance improvements when compared to the prototype. The computational results offer valuable insights for optimizing the flow characteristics of the enhanced product.

Geometry dimension optimization of a liquid–gas vacuum ejector for MED-TVC system

• Establishing the 3D model for the design and optimization of liquid–gas ejector. • The internal fluid flow characteristics of liquid–gas ejector was investigated. • The optimal NXP, area ratio and the length of mixing chamber were obtained. • A correlation between geometric parameters and ejector performance is developed. A liquid–gas ejector is designed to entrain the non-condensable gas accumulating in the condenser without power consumption in the multi-effect distillation with a thermal vapor compression desalination system and the geometry dimensions are optimized by the optimization method provided in this paper for their vital influence on liquid–gas ejector performance. In this paper, the effects of nozzle exit position, area ratio, and the mixing chamber length on liquid–gas ejector are investigated simultaneously using numerical simulations. The results show that: the mass flow rate ratio and efficiency increase within a certain range and then decrease while the nozzle exit position increases; the mass flow rate ratio increases with the increasing of area ratio, meanwhile, the efficiency increases until reaching a maximum value and then decreases; there is no obvious effect on system vacuum degree as the mixing chamber length increases. Following this, the optimal geometry parameters including nozzle exit position, area ratio, and mixing chamber length are determined. When NXP is 16.95 mm, the area ratio is 4.45 and the length of the mixing chamber is 92.5 mm, the liquid–gas ejector has the best performance with the efficiency, mass flow rate ratio, and vacuum degree of 0.5, 2.02, and 0.18 atm, which satisfies the design requirements. Through the geometry optimization method, the liquid–gas ejector can effectively remove the non-condensable gas from the condenser instead of the mechanical pump in the vacuum system under a typical working condition of the multi-effect distillation with thermal vapor compression desalination system.

Numerical Investigation on a Liquid–Gas Ejector for Carbon Dioxide Removal Using Amine Solution: Hydrodynamics and Mass Transfer Evaluation

The present study investigates the hydrodynamics and mass transfer of the liquid–gas ejector using three-dimensional (air–water) and two-dimensional (CO2/air-MEA (Monoethanolamine) solution) computational fluid dynamics (CFD) modeling. For 3D simulation, validation of the CFD results of this ejector with experimental data (error less than 5%) showed high simulation accuracy. The effects of motive liquid flow rate and outlet pressure parameters on the air entrainment rate and air hold-up are also investigated. It was found that by increasing the outlet pressure by about 70% (from 3587 to 6127 Pag), the rate of gas entrainment and gas hold up decreased by about 37% and 20%, respectively. On the contrary, these parameters showed increasing behavior of about 74% and 15%, respectively, when the mass flow rate of liquid increased by about 21%. In addition, three-dimensional phenomena such as mixing shock and the location of its occurrence are examined, which is the reason for recirculation and vortex in the ejector. Next, by simulating a two-dimensional simulation and changing the inlet fluids to CO2/air-methanol amine, the ejector was designed to simultaneously increase the gas pressure and absorb carbon dioxide. A user-defined function code was used to express the mass transfer from the gas to the liquid phase. The results, in this case, showed that with increasing the outlet pressure of the ejector (from 0 to 2000 Pag), and enhancing the concentration of MEA solution (from 10% to 30%), the CO2 removal boosted from 83% to 95%. A similar behavior was shown when the L/G ratio increased from 3.5 to 5.5. This study serves as a showcase on how to do an exact design and analysis for liquid–gas ejectors in flare gas recovery systems.

Analysis of Gas Collection Systems in the Fields of Uzbekistan

Annotation: Giant gas fields play an important role in the development of the world natural gas industry. The major gas producers have established their positions on the world arena with the support of their discovery and development of several or more giant gas fields. In Uzbekistan, special attention is paid to oil and gas production, which is one of the sources of economic development. Keywords: water vapor, liquid water, carbon monoxide, sulfuric acid H2S, nitrogen N2, and helium He, linear, light, ring collection system, the gas ejector, hydrocarbons

Improvement of the Liquefied Natural Gas Vapor Utilization System Using a Gas Ejector

The production, transportation, and storage of liquefied natural gas (LNG) is a promising area in the gas industry due to a number of the fuel’s advantages, such as its high energy intensity indicators, its reduced storage volume compared to natural gas in the gas-air state, and it ecological efficiency. However, LNG storage systems feature a number of disadvantages, among which is the boil-off gas (BOG) recovery from an LNG tank by flaring it or discharging it to the atmosphere. Previous attempts to boil-off gas recovery using compressors, in turn, feature such disadvantages as large capital investments and operating costs, as well as low reliability rates. The authors of this article suggest a technical solution to this problem that consists in using a gas ejector for boil-off gas recovery. Natural gas from a high-pressure gas pipeline is proposed as a working fluid entraining the boil-off gas. The implementation of this method was carried out according to the developed algorithm. The proposed technical solution reduced capital costs (by approximately 170 times), metal consumption (by approximately 100 times), and power consumption (by approximately 55 kW), and improved the reliability of the system compared to a compressor unit. The sample calculation of a gas ejector for the boil-off gas recovery from an LNG tank with a capacity of 300 m3 shows that the ejector makes it possible to increase the boil-off gas pressure in the system by up to 1.13 MPa, which makes it possible to not use the first-stage compressor unit for the compression of excess vapours.

Thermodynamic Investigation of a Solar Energy Cogeneration Plant Using an Organic Rankine Cycle in Supercritical Conditions

In the present work, a novel Organic Rankine Cycle (ORC) configuration is used for a low-grade heat source cogeneration plant. An investigation is conducted accordingly into the simultaneous production of electricity and cold. The proposed configuration relies on concentrated solar power (as heat source) and ambient air (for cooling). Furthermore, two gas ejectors are added to the system in order to optimize the thermodynamic efficiency of the organic Rankine cycle. The results show that the thermodynamic and geometric parameters related to these ejectors have an important effect on the overall system performances. In order to account for the related environmental impact, the following working fluids are considered: HCFC-124, HFC-236fa, HFO-1234yf and HFO-1234ze. As shown by the numerical simulations, the fluid R1234yf presents the minimal heat consumption and therefore provides an optimal thermal efficiency for the ORC cycle (which is around 29%). However, the refrigerant R236fa displays the highest refrigeration performances with a performance coefficient reaching a value as high as 0.38.

Artificial neural network model for single-phase real gas ejectors

Ejector is a passive gas dynamic device used ubiquitously in engineering applications. Applications of ejectors have transited from traditional steam extraction to heat-driven gas compression in supercritical and trans-critical CO 2 power and refrigeration cycles. The non-ideal gas behavior in such applications adds to the existing lack of fundamental understanding of the complex gas dynamics within the ejector. A number of simplified 1-D physics-based low-fidelity models have been proposed in the literature. These models offer reasonably good predictions for most ideal gases such as air and superheated steam. However, significant deviations as high as 20% between the experimental measurements and the model are observed for real gases. On the other hand, CFD simulations for an ejector are not only computationally expensive but also require careful selection and tweaking of the turbulence model. The paper presents a data-driven artificial neural network (ANN) model to predict the critical parameters of a supersonic ejector. The model is trained using a comprehensive experimental database comprising of various working fluids and operating conditions. The framework uses a topology of seven dimensionless input parameters capturing geometry, operating conditions, and working fluid characteristics to predict two output parameters; (a) entrainment ratio and (b) operational regime of the ejector (critical or mixed mode of operation). The model relies on a network of 84 neurons in the hidden layer and uses a split ratio of 0.15 for training the dataset. The trained ANN model is able to predict the entrainment ratio within 10% accuracy, with the ability to classify the operational mode with an accuracy of 91%. • An ANN model is developed to predict the ejector performance and operating regime. • The working fluid is modeled with its molecular weight and isentropic exponent. • ANN predicts ER with a 10% deviation with experimental ER for all working fluids. • The ANN model classifies the operating regime of ejectors with 91% accuracy. • It will be effective in predicting the global performance of ejector-based systems.

Design modification of two-dimensional supersonic ejector via the adjoint method

A numerical investigation of a design modification of a two-dimensional supersonic gas ejector was undertaken via an adjoint method, with a focus on enhancing the performance of the ejector. Maximization of the secondary mass flow rate was used as an objective function. The entrance geometry and throat height of the primary nozzle were fixed, but the other geometries were allowed to vary during the design modification. The shape of the divergence of the primary nozzle, the nozzle exit position (NXP), and the entrance region of the mixing chamber were modified simultaneously using the adjoint method. The height of divergent section of primary nozzle (Hne), NXP, and the inlet height of the mixing chamber (Hmi) were enlarged by about 13.33%, 27%, and 49%, respectively, resulting in an entrainment ratio (ER) that was enhanced by about 37.17% compared to that obtained for the baseline geometry. Two simplified geometries from the adjoint modification were suggested, and have the same performance with the adjoint-modified geometry. Further investigation was performed by varying the height of the straight section of the mixing chamber of the simplified geometry. The results show that the ER increased by about 46.77% compared with that obtained using the simplified geometry.

Investigation on gas induction of liquid–gas ejector in jet loop reactor

Abstract Liquid–gas ejector as a key component of jet loop reactor (JLR), plays an important role in the continuous production of gas–liquid mixing reaction. In this paper, a formula for estimating the gas induction of the ejector is presented. The effects of nozzle radius and mixing length on gas induction of liquid–gas ejector for gas–liquid mixing are simulated, and the formula is verified. Focusing on the efficiency and gas induction, the geometrical parameters are analyzed for the same cases, so that the performance of the ejector can be thoroughly understood. The results show that the optimum mixing section length to diameter ratio (LDR) is about 5–7, and the decrease of nozzle outlet radius can increase the gas induction, which provides a reference for the evaluation of gas induction for liquid–gas ejector and has crucial guiding significance for the design of nozzle and mixing section of liquid–gas ejector in industry.

Experimental investigation on subcooling of liquid hydrogen by helium gas injection through evacuation

AbstractSubcooling is the process of bringing down the temperature of liquids lower than that of the boiling point of the corresponding vapor pressure. The performance of subcooling of cryogenic liquids mainly depends on the heat‐inleak of the system, the helium injection mass flow rate, helium injection temperature, and helium injection nozzle pattern. This paper presents an alternative method, by making use of the least heat in the leakage of the liquid hydrogen storage container, which is quite possible because containers with excellent thermal insulation are commercially available nowadays. The process involved is rapid evacuation through gas ejectors, thus reducing the effect of temperature. The advantage and the process of evacuation leading to subcooling in a unique manner are the objective of this article. The experimental results are discussed in comparison with the thermophysical process involved in the subcooling operation. A comparative study is also carried out with the theoretical heat exchange process in which helium is used as a medium for the economy of the stated process. It is stated that the current process of subcooling through evacuation is superior to the conventional heat exchange process.

Pengaruh perubahan spasi nosel pada aliran dua fase terhadap kinerja liquid-gas ejector

Liquid-gas ejector is an energy conversion device capable of flowing air fluid by utilizing water fluid based on the pressure difference between the two fluids without using moving parts. This study aims to determine the effect of changing nozzle spacing on the two-phase flow on the performance of the liquid-gas ejector. The method used is to carry out an experiment whose stages include: determination of nozzle spacing parameters, primary flow rate, and secondary flow rate. Then perform tests on the liquid-gas ejector installation and collect data. The test was carried out by alternately varying the nozzle spacing, primary flow rate, and secondary flow rate. Then analyze the data that has been collected to get the efficiency or performance of the liquid-gas ejector from changes in nozzle spacing. Increasing the nozzle spacing causes a decrease in the efficiency of the liquid gas ejector. The efficiency of the liquid gas ejector with nozzle spacing 5, 10, 15, 20, and 25 mm is 17.17%, 13.49%, 12.06%, 11.41, respectively. %, and 10.47%. Keywords: Nozzle spacing, flow, two phases, performance, liquid-gas ejector.

МЕСТНАЯ ВЫТЯЖНАЯ ВЕНТИЛЯЦИЯ С ЭЖЕКТИРОВАНИЕМ

Exhaust ventilation systems in industrial enterprises and facilities with the use of harmful substances largely determine the air exchange in the workplace to ensure normalized sanitary and hygienic conditions and operating costs. Local exhaust ventilation of explosive harmful substances is of particular importance for effective air exchange in such rooms, since their localization, suction and transportation are subject to increased requirements. The paper presents the results of analytical and experimental studies of the operation mode of a complex local exhaust device with a gas ejector for extraction explosive harmful chemicals from shelters, ensuring their effective localization, purification and recirculation of air. The boundary conditions and assumptions for calculating the characteristics of the processes of gas flow ejection, purification of technological emissions and recirculation of the purified gas flow, determined on the basis of the analysis of previously performed studies and experimental work, are given. The conditions of rational ratios device settings of extraction of emissions sources of substances that parameters of the ejector and cleaning device emission, which is achieved economic and environmental efficiency of the installation and excludes the volatile situation on the threat of chemical enterprises and objects.

Hydraulic characteristics of liquid–gas ejector pump with a coherent liquid jet

The gas suction rate of a conventional liquid–gas ejector pump was measured on a modular pilot plant unit utilizing convergent nozzles and a water–air system. Hydraulic characteristics were measured for various water flow rates, suction and discharge pressures, and ejector geometries, covering a wide range of configurations and operating conditions. The device configurations, providing the most stable and reproducible results, were identified. The air flow rates measured with these configurations were correlated by a simple, three-parameter correlation with a relative standard deviation (RSD) of 11%. The performance and behavior of the ejector in less stable configurations are discussed and the recommendations for the design of optimally operating units are provided. Finally, the correlation is tested against available literature data. The ejectors with comparable geometry agree well with the proposed correlation (within 20% RSD). The reasonable agreement with the discussed differences is found for other literature data. This comparison results in the validation of the proposed correlation to provide a safe prediction of minimal gas entrainment in units of various geometries, orientation and operating conditions.

Installation of Gas Ejector Provides Boost to Low-Pressure Gas Well

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 196440, “Giving a Boost to a Low-Pressure Gas Well by Installing a Gas Ejector,” by Ping Wei and Brian Macdonald, SPE, KUFPEC, prepared for the 2019 SPE Asia Pacific Oil and Gas Conference and Exhibition, 29-31 October, Bali, Indonesia. The paper has not been peer reviewed. To further reduce backpressure on low-pressure gas wells and increase reserves in a mature gas field, a gas-ejector project was evaluated and proposed. Following on-site tests on several gas wells, the gas ejector was put into service successfully. Reservoir simulation estimates that 6.4 Bcf of incremental reserves will be achieved through gas-ejector installation by decreasing inlet pressure to 50 from 100 psi. The application of the gas ejector during a 2-year period to reduce backpressure has helped to improve economics in a mature gas field.