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In reciprocating internal combustion engines, the calculation of the heat transfer coefficient (HTC) is essential to estimate the heat transfer during combustion in the combustion chamber. The HTC calculation takes into account fluid flow and combustion processes and varies as a function of crank angle and location within the chamber. The mean HTC value is commonly used to calculate the thermo-mechanical analysis of various combustion chamber components. In this study, dynamic grids for the intake port, exhaust port and chamber are created in the chamber modelling section of the AVL-Fire software. The intake and combustion processes are then simulated and the calculated pressure data are compared with experimental data at 2800 rpm with 1, 3 and 6 hole injectors. Finally, the distribution of HTC over the chamber walls was evaluated using a time step method. The research also included verification of the HTC results with theoretical data obtained by Woschni and Hohenberg. In addition, with the decreasing availability of fossil fuels and the need for lower exhaust emissions from diesel engines, the use of blends of diesel and hydrogen fuel has become widespread. In this engine, a mixture of 10 % hydrogen and 90 % diesel fuel is used. The final results show that the heat transfer coefficient increases by approximately 1.72 % when hydrogen is added to diesel fuel due to the number of collisions between hydrogen and other fuel components. • Increasing the number of injector holes reduces the pressure in the cylinder. • Adding hydrogen to diesel fuel increases the heat transfer coefficient. • Adding hydrogen to diesel fuel increases engine power and NOx. • Increasing the number of nozzle holes reduces the depth of fuel penetration into the combustion chamber. [ABSTRACT FROM AUTHOR]

A significant amount of energy in wastewater treatment plants is spent on aeration to treat the organic matter with microorganisms in an oxygen-enriched environment. In this study, a novel and simplistic aeration concept known as Confined Tube Aeration (CTA) is proposed, in which the main elements are a Venturi injector and a coiled tube at its outlet. Two Venturi injector diameters were chosen for evaluation in this study, measuring 1 inch (25.4 mm) and 4 inch (101.6 mm). In this study, a relationship was developed between air suction rate and pressure differential across the injector. Then, a numerical model was developed to analyze hydrodynamic conditions and evaluate system performance. The main findings are that the larger diameter aerator performs 20% better than the smaller injector in terms of standard aeration efficiency (SAE), with a maximal value of 0.74 kgO2/kWh found for the larger diameter system. These results suggest that future SAE improvements may be made for larger diameter systems in full-scale wastewater treatment applications with suitably designed injectors. [ABSTRACT FROM AUTHOR]

The performance of detonation engines depends on propellant injectors. This study investigates a fluidic-valve injector mounted to a detonation tube. The injector is equipped with a recessed cavity connecting to the fuel plenum. After verifying the theoretical and numerical framework, three cases (I, II, and III) are analyzed, each representing different combinations of initial injector conditions and fuel supply setups. In all cases, a detonation wave is initiated near the headend of the detonation tube. It propagates through the initial section of the tube and undergoes diffraction and deformation at the flush-wall orifice. Among the considered cases, Case III, featuring a pre-pressurized initial injector flowfield and a total-pressure-inlet boundary, demonstrates the best agreement with the experimental results. It reveals a strong interaction between the longitudinally traveling detonation wave and the transverse propellant plume expanding from the orifice, causing the detonation wave to split. One part continues within the tube, while the other diffracts into the injector, creating a recirculation zone. Shock waves propagate within the injector and reflect at the base of the cavity, generating pressure spikes similar to the experimental observations. However, the contact surface separating the burnt products and fresh propellant reaches only a limited distance into the injector, suggesting a short interruption time and rapid recovery of the propellant supply. [ABSTRACT FROM AUTHOR]

In this paper, both analytical and numerical analyses are conducted to study the behavior of a simplex time injector with a swirl chamber represented by a pin, designed to operate with kerosene. In an effort to reduce chemical pollution, the injector's performance when operating with alternative fuels such as biofuel and ethanol is investigated. Calculations have been performed to analyze the use of these three fuels at various pressures up to 100 bar. Analytical calculations were used to determine parameters such as spray angle, droplet size, fuel film thickness, and more. For a better visualization of the phenomena occurring during the injector's operation with these three fuels, numerical simulations were carried out using ANSYS, and the spray of droplets at various pressures at the injector inlet was presented. The study revealed that among the liquids studied, ethanol is the most optimal fuel. Ethanol has low viscosity and low density, making it easier to atomize by our injector compared to pure biofuel, which has higher density and viscosity values. The calculations demonstrated the qualities of ethanol following atomization, including a thin liquid film, a wide spray angle consisting of small-sized droplets, at any pressure difference, compared to the other studied fuels. It was observed that pressure difference has a significant impact on the atomization of a liquid. The best atomization qualities and optimal values were achieved when the pressure difference is high.

The jet pump is one of the most popular types of fluid machinery in agriculture, industry and environmental engineering and many other fields. However, its internal flow structure is complex, showing obvious unsteady characteristics. The effect of throat diameter size on jet pump performance and energy property was investigated in this study based on numerical calculation and test verification, in order to improve the performance and internal flow field stability of jet pump. Five models with different throat diameters were obtained by adjusting the assembly structure and simulated by the computational fluid dynamics software to solve the Navier–Stokes equations for three-dimensional steady flow. The accuracy of numerical methods was verified by comparison with the experimental results. The compact jet pump performance under different throat diameters was then compared and analysed. The backflow at effuser outlet of different throat diameters causes the changes of vortex structure inside the injector rear chamber. The vortex diffuses downstream to the impeller inlet, making the flow structure of the impeller inlet show obvious circumferential inhomogeneity. This forms different vortex structures at different impeller flow channels, changing the distribution of entropy production within the impeller, ultimately leading to a decrease of pump efficiency. Therefore, this study found that selecting a reasonable throat diameter of the injector can improve the performance of the jet pump impeller, and thus improve the overall efficiency of the system. For the research object in this paper, the recommended range of throat diameter of injector is 16 mm–17 mm. This finding could provide useful insights for the improvement of the hydraulic performance and operational stability of compact jet pumps.

A model-based study is conducted to optimize the dynamic performance of a solenoid actuator in a compressed natural gas (CNG) injector. A mechanical model, an electromagnetic model, and an optimum model using particle swarm optimization (PSO) algorithm are built to depict operation and optimize the dynamic response times of the injector solenoid actuator. Effects of the number of coil turns (N), spring stiffness (k), and gap between plunger and cylinder wall (g), on the dynamic characteristics of the injector solenoid actuator are investigated. Simulation results show that, when k increases from 560 to 2560 N/m, and g increases from 0.1 to 0.5 mm, the opening response time increases 35.41% and 48.03%, respectively; however, the closing response time of the injector solenoid actuator reduces 27.27% and 45.25%, respectively. When N is increased from 342 to 552, the opening response time reduces 35.48%; nevertheless, the closing response time increases considerably with a 195.45% increment. Using PSO algorithm, it is found that the optimum version of the injector solenoid actuator has improvements for both opening and closing response times, in which the opening response time reduces 11.41% when compared with the original version. [ABSTRACT FROM AUTHOR]

Background. The relevance of the topic is determined by the prevalence of monitoring and control tasks for civil engineering products in order to prevent the occurrence of emergency situations. The goal of the work is to develop and master in mass production of unified rows of multilayer piezo-film ceramic elements based on the piezoelectric effect using slip casting technology for the control system of internal combustion engines. Materials and methods. The work uses slip casting and cold semi-dry pressing technologies. Results. The results of research into the technology for creating multilayer piezo actuators for injectors of internal combustion engines, manufactured using slip casting technology, are presented. The technical characteristics of laboratory samples of multilayer piezo actuators manufactured using semi-dry cold pressing technology are presented. The obtained value of the relative working stroke at a control electrical voltage of 200 V ranged from 0.05 to 0.08 %, and at minus 200 V it ranged from minus 0.06 to minus 0.033 %. Further improvement of the technical characteristics of piezo actuators manufactured using semi-dry cold pressing technology, including an increase in the relative working stroke to 0.13 % at a control electrical voltage of 140 V, is possible by reducing the thickness of the piezo plate blanks from 0.2 to 0.1 mm and changes in the method of their metallization and assembly (gluing).

Ammonia in anhydrous and aqueous forms, are attractive carbonless fuels for future marine diesel engines. The aim of this study was to determine if these fuels could be injected into a two-stroke marine diesel engine using a unit injector system. In this study, existing in service injector hardware was used to develop a dynamic numerical injector model. The results of the simulation were then validated against injector performance literature obtained for an engine, using conventional diesel fuel oil. Using the developed numerical model, the injection performance of anhydrous and aqueous ammonia solutions could then be investigated. The study found good correspondence between the model and the pressure trace found in literature. In terms of fuel injection performances, it was found that both fuels were injectable with a unit injector, however the correct volume and mass required were not achieved. Furthermore, injection timing and duration were affected marginally. For aqueous ammonia, with the higher bulk modulus, injection was advanced by 0.21 CA degrees and for anhydrous ammonia with a lower bulk modulus; it was delayed by 0.21 CA degrees. Overall proper operation of the injection system was observed. This outcome is promising, especially in shifting the maritime industry towards zero carbon ammonia engines. • Dynamic mechanical behaviour of ammonia fuel injector was simulated. • Aqueous ammonia, anhydrous ammonia and marine diesel oil were compared. • The higher bulk modulous of aqueous ammonia advanced fuel injection timing. • Ammonia and aqueous ammonia require design changes to deliver higher mass. [ABSTRACT FROM AUTHOR]

The results of development of the lithium injector for the T-11M tokamak on the basis of ultrasonic method for microdrop generation are presented. The physical substantiation of initial data for designing the finely dispersed lithium injector for the tokamak is given. The experimental results and techniques for determining the injector parameters under test-bench conditions and under plasma discharge conditions in the T‑11M tokamak's chamber are presented. It is shown that the created design of the lithium injector allows the generation of a flow of lithium microdrops with an average diameter of 80 µm and a mean velocity of 5–8 m/s at the injector productivity of 12–15 mg/s. The technological features of using the ultrasonic injector under the tokamak conditions are studied, which are related to the synchronization of the injector triggering with the plasma discharge and to the effect of the lithium surface purity on the particle flow parameters. [ABSTRACT FROM AUTHOR]

The paper considers the conversion of an aircraft combustion chamber with a two-level arrangement of injectors to natural gas. The design features of the aircraft combustion chamber and the combustion chamber using the natural gas are considered. The structural elements that have been modified are given. A design changes for ensuring operation on natural gas are rationalized. [ABSTRACT FROM AUTHOR]

This article covers concerns about the elimination of low-value deciduous trees by chemical treatment in favour of conifers. Various methods for removing undesirable vegetation are discussed with an indication of their advantages and disadvantages. Central attention is given to the use of arboricides for the treatment of young growth. It is considered that the chemicals must selectively affect the unfavourable plants, avoid any influence on economically valuable species, and be safe for human health and forest fauna. A practically common method of chemical maintenance was investigated, which includes the injection of arboricides into notches on tree trunks. The authors suggest devices confirmed by the patents of the Russian Federation that are suitable for this purpose. The operational principle is the drilling of the notches with the subsequent injection of arboricide. The proposed mechanical treatment increases productivity by decreasing the complexity of the procedure as well as the physical load on the operator during handling and moving of the equipment. The investigational results are compared with the properties of the Cobra apparatus, which was widely used in the Soviet Union and later in the Russian Federation. The research was performed in young stands of Kokshaysky Forest and Shulkinskoe Forestry in the Republic of Mari El. The comparative results of ecological and silvicultural monitoring on coniferous conditions after chemical treatment revealed the higher performance of the proposed device over the Cobra apparatus. The material in this article is recommended to forestry operators as a guide for chemical maintenance, mainly in young stands. For citation: Tsarev E.М., Rukomojnikov K.P., Anisimov S.E., Konyukhova Т.А., Krenev А.V. Improving Chemical Maintenance Techniques in Forest Plantations. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 4, pp. 190–201. (In Russ.). https://doi.org/10.37482/0536-1036-2023-4-190-201

A significant amount of energy in wastewater treatment plants is spent on aeration to treat the organic matter with microorganisms in an oxygen-enriched environment. In this study, a novel and simplistic aeration concept known as Confined Tube Aeration (CTA) is proposed, in which the main elements are a Venturi injector and a coiled tube at its outlet. Two Venturi injector diameters were chosen for evaluation in this study, measuring 1 inch (25.4 mm) and 4 inch (101.6 mm). In this study, a relationship was developed between air suction rate and pressure differential across the injector. Then, a numerical model was developed to analyze hydrodynamic conditions and evaluate system performance. The main findings are that the larger diameter aerator performs 20% better than the smaller injector in terms of standard aeration efficiency (SAE), with a maximal value of 0.74 kgO2/kWh found for the larger diameter system. These results suggest that future SAE improvements may be made for larger diameter systems in full-scale wastewater treatment applications with suitably designed injectors.

In this paper, both analytical and numerical analyses are conducted to study the behavior of a simplex time injector with a swirl chamber represented by a pin, designed to operate with kerosene. In an effort to reduce chemical pollution, the injector's performance when operating with alternative fuels such as biofuel and ethanol is investigated. Calculations have been performed to analyze the use of these three fuels at various pressures up to 100 bar. Analytical calculations were used to determine parameters such as spray angle, droplet size, fuel film thickness, and more. For a better visualization of the phenomena occurring during the injector's operation with these three fuels, numerical simulations were carried out using ANSYS, and the spray of droplets at various pressures at the injector inlet was presented. The study revealed that among the liquids studied, ethanol is the most optimal fuel. Ethanol has low viscosity and low density, making it easier to atomize by our injector compared to pure biofuel, which has higher density and viscosity values. The calculations demonstrated the qualities of ethanol following atomization, including a thin liquid film, a wide spray angle consisting of small-sized droplets, at any pressure difference, compared to the other studied fuels. It was observed that pressure difference has a significant impact on the atomization of a liquid. The best atomization qualities and optimal values were achieved when the pressure difference is high. [ABSTRACT FROM AUTHOR]

One factor limiting the exploitation of hydrogen as a fuel in internal combustion engines is their tendency to autoignition. In fact, on one hand, its low activation energy facilitates autoignition even with low compression ratios; on the other hand, this can become uncontrollable, due, for instance, to the presence of hot spots in the combustion chamber or to the collision of hydrogen on close surfaces. This represents a limit to the use of hydrogen at medium–high loads, therefore limiting the power density of the engine. In this work, hydrogen was injected at a pressure ranging between 15 and 25 bars into a constant-volume combustion chamber in which the temperature and pressure were increased by means of a previous combustion event. The phenomena taking place after hydrogen injection were observed through fast image acquisition and characterized by measuring the chamber pressure and temperature. In particular, ignition sites were established. The physical system was also modeled in Ansys Fluent environment, and the injection and mixture formation were simulated in order to evaluate the thermo-fluid dynamic field inside the combustion chamber just before autoignition. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Drainage & Irrigation Machinery Engineering / Paiguan Jixie Gongcheng Xuebao is the property of Editorial Department of Drainage & Irrigation Machinery Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biological products often contain microbial inoculants and/or organic ingredients that are marketed as being capable of improving nutrient use efficiency and promoting sustainability through their impact on plant and soil health. However, there is lack of field research on their efficacy. A study was conducted in Johns Creek, Georgia, USA, to evaluate the effects of two biological products (BP1, BP2) on soil biological health and turf quality. A unique delivery system was used for applying the products directly in the root zone and for aeration. Soil biological health was evaluated by determining microbial abundance and function. Turf quality was expressed as % normalized difference vegetation index based on digital images of plots. The biological products did not significantly impact the soil health parameters that included abundance of ammonia oxidizers, soil respiration, urease, and phosphatase activities. Similarly, they did not have any significant impact on turf quality and health. This could indicate that the products' active ingredients were not effective under the study conditions. One possible reason is they were applied on the top of the standard inputs as recommended by the manufacturer, and that they were not addressing any limiting factor in the system. The only significant difference was between the two products in which subsurface application of BP2 resulted in higher abundance of ammonia oxidizers than surface application of BP2 and BP1. The study highlighted the need to evaluate the efficacy of biological products and to identify conditions under which they can be beneficial before they are extensively used. [ABSTRACT FROM AUTHOR]

The performance of detonation engines depends on propellant injectors. This study investigates a fluidic-valve injector mounted to a detonation tube. The injector is equipped with a recessed cavity connecting to the fuel plenum. After verifying the theoretical and numerical framework, three cases (I, II, and III) are analyzed, each representing different combinations of initial injector conditions and fuel supply setups. In all cases, a detonation wave is initiated near the headend of the detonation tube. It propagates through the initial section of the tube and undergoes diffraction and deformation at the flush-wall orifice. Among the considered cases, Case III, featuring a pre-pressurized initial injector flowfield and a total-pressure-inlet boundary, demonstrates the best agreement with the experimental results. It reveals a strong interaction between the longitudinally traveling detonation wave and the transverse propellant plume expanding from the orifice, causing the detonation wave to split. One part continues within the tube, while the other diffracts into the injector, creating a recirculation zone. Shock waves propagate within the injector and reflect at the base of the cavity, generating pressure spikes similar to the experimental observations. However, the contact surface separating the burnt products and fresh propellant reaches only a limited distance into the injector, suggesting a short interruption time and rapid recovery of the propellant supply.

We consider the possibility of solving the inverse problem of calculating a gas–liquid jet injector with a bubbly two-phase flow structure. The parameters governing the injector operation, such as the pressure difference, the orifice diameter, and the air concentration, are determined for the given value of the mean Sauter diameter. For this purpose, the operation of a mixer with a two-phase working body and injectors of different diameters was experimentally investigated in the bubbly operation regime with a water–air working body. In the experiments the parameters of the phases supplied to the mixer (flow rates, pressures, and temperatures) were measured, together with the pressure ahead of the injector. The dispersity and velocity parameters in the spray were measured using the laser shadow method. The statistics thus gathered allow one to obtain the required correlation dependences which makes it possible to solve the problem formulated. [ABSTRACT FROM AUTHOR]

It is well established that spray characteristics from automotive injectors depend on, among other factors, whether cavitation arises in the injector nozzle. Bulk cavitation, which refers to the cavitation development distant from walls and thus far from the streamline curvature associated with salient points on a wall, has not been thoroughly investigated experimentally in injector nozzles. Consequently, it is not clear what is causing this phenomenon. The research objective of this study was to visualize cavitation in three different injector models (designated as Type A, Type B, and Type C) and quantify the liquid flow field in relation to the bulk cavitation phenomenon. In all models, bulk cavitation was present. We expected this bulk cavitation to be associated with a swirling flow with its axis parallel to that of the nozzle. However, liquid velocity measurements obtained through particle image velocimetry (PIV) demonstrated the absence of a swirling flow structure in the mean flow field just upstream of the nozzle exit, at a plane normal to the hypothetical axis of the injector. Consequently, we applied proper orthogonal decomposition (POD) to analyze the instantaneous liquid velocity data records in order to capture the dominant coherent structures potentially related to cavitation. It was found that the most energetic mode of the liquid flow field corresponded to the expected instantaneous swirling flow structure when bulk cavitation was present in the flow. [ABSTRACT FROM AUTHOR]

During a severe accident in nuclear power plant, if passive containment cooling system fails and other pressure relief measures are also useless, the mixed gas in containment can be injected into the spent fuel pool via a injector to reduce the risk of containment overpressure failure and the release of radioactivity to the environment. A aerosol pool scrubbing facility was built to study the factors influencing the effect of aerosol pool scrubbing under the injector. This facility can perform a great variation of experiments using various measurement tools. The aerosol concentration and particle size were monitored by using the spectrometer with a 20% measurement error. TiO2 powder was used as a stimulant for the aerosols in containment, and the mass median diameter ranged from 0.5 to 1.5 μm, the geometric standard deviation ranged from 1.63 to 2.15. According to the different characteristics of gas-liquid hydrodynamic behavior, the pool scrubbing process can be divided into two regions, including injection and rise zones. In the injection zone, with the flow flux increase, the gas regime changed from bubble (We

Mixture formation is one of the greatest challenges for the development of robust and efficient hydrogen-fueled internal combustion engines. In many reviews and research papers, authors pointed out that direct injection (DI) has noteworthy advantages over a port fuel injection (PFI), such as higher power output, higher efficiency, the possibility of mixture stratification to control NO x -formation and reduce heat losses and above all to mitigate combustion abnormalities such as back-firing and pre-ignitions. When considering pressurized gas tanks for on-vehicle hydrogen storage, a low-pressure (LP) injection system is advantageous since the tank capacity can be better exploited accordingly. The low gas density upstream of the injector requires cross-sectional areas far larger than any other injectors for direct injection in today's gasoline or diesel engines. The injector design proposed in this work consists of a flat valve seat to enable the achievement of lifetime requirements in heavy-duty applications. The gas supply pressure is used as the energy source for the actuation of the valve plate by means of a pneumatic actuator. This article describes the design and the performed tests carried out to prove the concept readiness of the new LP-DI-injector. • Direct injection of gaseous hydrogen at pressure levels of 20 bar. • Scalable design to meet flow requirements for heavy-duty applications with different cylinder displacements. • Design featuring a flat seat with a ceramic valve plate to achieve a high level of wear resistance. • Pneumatic actuation using a solenoid actuated pilot valve. • Concept readiness proved by means of rig testing and fired engine testing. [ABSTRACT FROM AUTHOR]

Enrichment of the methane fraction in a biogas mixture is an innovative possibility to make existing biogas plants more flexible by using excess power. In the described concept, the CO2 in the biogas is directly catalytically converted into CH4 with H2. The CH4‐enriched biogas is again fed into the digester to save energy for later use in the combined heat‐and‐power unit. Additionally, the fed heat gas can mix and heat the substrate. A heat pipe injector system was therefore developed for cooling the hot biogas stream after methanation and to prevent damage to the microbial consortia during the biomass mixing. The concept was proven at a laboratory‐scale biogas plant. [ABSTRACT FROM AUTHOR]

One factor limiting the exploitation of hydrogen as a fuel in internal combustion engines is their tendency to autoignition. In fact, on one hand, its low activation energy facilitates autoignition even with low compression ratios; on the other hand, this can become uncontrollable, due, for instance, to the presence of hot spots in the combustion chamber or to the collision of hydrogen on close surfaces. This represents a limit to the use of hydrogen at medium–high loads, therefore limiting the power density of the engine. In this work, hydrogen was injected at a pressure ranging between 15 and 25 bars into a constant-volume combustion chamber in which the temperature and pressure were increased by means of a previous combustion event. The phenomena taking place after hydrogen injection were observed through fast image acquisition and characterized by measuring the chamber pressure and temperature. In particular, ignition sites were established. The physical system was also modeled in Ansys Fluent environment, and the injection and mixture formation were simulated in order to evaluate the thermo-fluid dynamic field inside the combustion chamber just before autoignition.

Serial femtosecond crystallography (SFX) using an X-ray free electron laser (XFEL) enables the determination of room-temperature structures without causing radiation damage. Using an optical pump-probe or mix-and-injection, SFX enables the intermediate state visualization of a molecular reaction. In SFX experiments, serial and stable microcrystal delivery to the X-ray interaction point is vital for reasonable data collection and efficient beam time. The Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL) facility established SFX instruments at a nanocrystallography and coherent imaging (NCI) experimental station. Various sample delivery methods, including injection, fixed-target scanning, and hybrid methods, have been developed and applied to collect XFEL diffraction data. Herein, we report the currently available sample delivery methods for SFX at the NCI experimental station at the PAL-XFEL. This article will help PAL-XFEL users access the SFX system for their experiments. [ABSTRACT FROM AUTHOR]

To have energy sustainability and reduce emissions, it is essential to use alternative fuels in IC engines and improve their performance by using fuel combinations. In diesel engines, the fuel atomization process strongly affects combustion and emissions. The injector hole number of a fuel injector nozzle also plays a critical role in influencing the performance and emissions of diesel engines and is an important part of the diesel engine. In general, both parameters affect the spray parameters like droplet size and penetration length and thus the combustion process. In the present work, different injectors (4-hole injector with a nozzle diameter of 0.25 mm, 3-hole injector with a nozzle diameter of 0.20 mm) are used to study the performance and emissions characteristics of DI-CI diesel engine fuelled with a blend of Multi-Walled Carbon Nanotubes and Tallow Oil Methyl Ester. Multi-Walled Carbon Nanotubes were doped at 5, 10, 15, and 20 ppm into the test fuels. The experimental results revealed that the brake thermal efficiency of the engine slightly decreases when the engine is fueled by completely TOME biodiesel. Then the addition of Multi-Walled Carbon Nanotubes into the diesel-Tallow oil biodiesel blend improves the BTE. Furthermore, Multi-Walled Carbon Nanotubes lead to a noteworthy reduction in exhaust pollutants. Accordingly, all emissions (CO, HC, NOx, and smoke) were reduced with Multi-Walled Carbon Nanotubes in the test fuels thanks to the high surface area to volume ratio, higher energy content, catalyst role, accelerating chemical reactions, and oxidization of more unburnt fuels. Diesel–biodiesel blend with 20 ppm Multi-Walled Carbon Nanotubes exhibits superior performance and emissions characteristics among all blends. The BTE of the B40D60C20 blend was almost equivalent to that of diesel and has nearly equal emissions levels compared to diesel fuel under full and part load conditions. The B40D60C20 blend showed a maximum BTE of 30.9% which is 15.53% higher than raw TOME and 3.43% lower than diesel fuel. In addition to that, the blend B40D60C20 showed a significant reduction in CO emissions by 45.46%, HC by 17.29%, NOx by 15.25%, and smoke by 21.28% compared to the raw TOME. Therefore, the optimized fuel blend is B40D60C20 with a dose level of 20 mg/L, where a reasonable improvement in performance and emissions characteristics has been achieved. Additionally, a smaller nozzle diameter for injectors leads to better injection characteristics and a small size for atomized fuel droplets. Accordingly, better results in terms of engine performance and emissions characteristics are achieved for the injector having three-hole with a diameter of 0.20 mm. The optimized fuel combinations with the optimized nozzle geometry will lead to better IC engine performance. The response surface methodology and artificial neural network outcomes demonstrated that these two are excellent modelling techniques, with good accuracy. In addition, the artificial neural network's prediction performance was somewhat better than the response surface methodology. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction. Some physical processes active in the electronic engine control systems lead to wear and tear of the system elements. Experience in operating and diagnosing vehicles at the service station has shown that there is the operation of vehicles with failures, many of which subsequently lead to malfunctions of different complexities. The purpose of the study is to apply diagnostics for determining the operational reliability and assessing the technical condition of electronic engine control systems. Materials and Methods. A batch of cars was selected to assess the operational reliability of modern electronic engine control system. There were carried out experimental tests of Skoda Octavia cars with 1.8 TSI CDAB 152 hp Euro5 engine and CDAA 160 hp Euro5 engine. The sample consisted of 60 vehicles. Every vehicle was registered for diagnostics, pre-maintenance and computer diagnostics. After a short test, the vehicle was taken back to the service station and subjected to a detailed diagnosis of the electronic engine control system. Results. The results of analyzing reliability of the main elements of the electronic engine control system have been obtained. It can be concluded that most of the failures of the structural elements of the electronic engine control system occur within the actuators of the system, which have moving elements, sensors measuring the parameters of the system wear out to a lesser extent. The analysis of dependence of failure rates of the fuel pump pressure regulator on operating time intervals has been carried out. Discussion and Conclusion. It was determined that the spark plugs have the least mileage lifetime. At the same time, the failure within the fuel pressure regulator of the car fuel system occurs most frequently (19.8% of total). The resource of this element of the electronic engine control system averages 125,000 km. It is proved that diagnostics using modern technological equipment is effective.

It is well established that spray characteristics from automotive injectors depend on, among other factors, whether cavitation arises in the injector nozzle. Bulk cavitation, which refers to the cavitation development distant from walls and thus far from the streamline curvature associated with salient points on a wall, has not been thoroughly investigated experimentally in injector nozzles. Consequently, it is not clear what is causing this phenomenon. The research objective of this study was to visualize cavitation in three different injector models (designated as Type A, Type B, and Type C) and quantify the liquid flow field in relation to the bulk cavitation phenomenon. In all models, bulk cavitation was present. We expected this bulk cavitation to be associated with a swirling flow with its axis parallel to that of the nozzle. However, liquid velocity measurements obtained through particle image velocimetry (PIV) demonstrated the absence of a swirling flow structure in the mean flow field just upstream of the nozzle exit, at a plane normal to the hypothetical axis of the injector. Consequently, we applied proper orthogonal decomposition (POD) to analyze the instantaneous liquid velocity data records in order to capture the dominant coherent structures potentially related to cavitation. It was found that the most energetic mode of the liquid flow field corresponded to the expected instantaneous swirling flow structure when bulk cavitation was present in the flow.

Cavitation is a physical phenomenon that often occurs in hydraulic machines such as pumps, valves, and turbines. Although the Banki-Michell turbine has been used for a long time in small hydropower, no study related to this phenomenon of cavitation in the injector of this turbine has been done. In this study, we will present the results of a numerical study carried out in the nozzle of a Banki-Michell turbine. The numerical solution of the Navier Stokes cavitation equations of the Banki-Michell turbine injector was carried out considering a 2D geometry of the injector-rotor assembly. The simulation results showed that the cavitation phenomenon appears when the water flow area in the nozzle becomes less than 50%. Furthermore, the results also showed that the occurrence of this cavitation phenomenon in the injector is more likely at higher operating heads. The results of an experimental study of the geometry of the injector showed that the height of the water passage section varies linearly with the degree of opening of the stator valve.

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This paper presents an innovative one-dimensional mathematical model applied to the on-line measurement for transient discharge coefficient of diesel injector nozzle. The state change in the fuel system is abstracted into the transfer and evolution process of the Riemann wave, and a direct mathematical relationship between the pressure and the transient discharge coefficient in a single Riemann wave environment is established. The on-line calibration method of fuel sound velocity is proposed, which avoids the complicated off-line calibration of fuel physical property. The time-domain characteristics recognition method of input signal is put forward and the model is segmented according to time characteristics to improve the applicability. The decoupling algorithm of reflected wave and the correction method of interference wave are proposed to improve the model robustness. The experimental results show that this mathematical model has good accuracy. It is found that the variation of the average discharge coefficient with injection pressure and pulse width is nonlinear due to the cavitation and needle valve average opening. [ABSTRACT FROM AUTHOR]

The UCI Rocket Project is an undergraduate engineering design team at the University of California, Irvine, dedicated to the design and development of liquid bi-propellant rockets. The team’s main goal is to design a liquid rocket capable of reaching 100 km for the Base11 Space Challenge. The current iteration of the rocket is designed to reach 45,000 ft as a preliminary verification of the team’s design and manufacturing capabilities. The design utilizes a pressure fed system with a propellant combination of liquid methane and liquid oxygen. As the team moves further into the testing and verification stages, development of the rocket capable of reaching 100 km begins. There are a total of four launch windows for the Base11 competition that begin in May 2020 and end in December 2021. The team has a dedicated lab space with the resources necessary for general design and assembly, but manufacturing is typically contracted to professional companies. As the space industry continues to grow, the UCI Rocket Project will continue giving undergraduate students relevant and impactful hands-on experience to prepare them for the challenges of working in the industry.Advisors: Professor Mark WalterProfessor Ken Mease

For decades, hydropower has been the most important renewable energy source in the world. The use of Banki-Michell turbine (B-M) in small hydropower constitutes an attractive solution for rural electrification in developing countries and off-grid applications. This robust turbine is easy to design and to construct and not expensive. A test bench (JLA 29) for remote applications was installed at the Aero-Thermo-Mechanics Department of the Brussels Polytechnic School of ULB to test this type of turbine. This paper aimed to present the efficiency results of the installed Banki-Michell turbine test bench for remote applications and these results helped to design a typical turbine adapted for remote sites such as the Ryamukona site located in Burundi. Two series of B-M turbine tests were carried out, by varying the flow rate using the turbine control valve opening placed inside the distributor and also by controlling the turbine speed using a Sinamics S 120 drive. The efficiency of the turbine varies between 40 and 60% for a flow range varying between 15 and 20% of the nominal flow. According to the tests made with a discharge above 20%, the efficiency of the turbine can reach easily 75 %. Based on this turbine efficiency, a typical B-M turbine of an electric power of 79.5 kWe turbine was designed for Ryamukona site which is a remote site located in Burundi.

The fuel injector is a critical component of the internal combustion engine. The diameters of the injector nozzle and the control chamber's oil inlet and outlet are generally between 0.2 and 0.5 mm, which are typical microchannel structures. During high-pressure injection, the cavitation phenomenon in the channel seriously affects the reliability of the internal combustion engine. The choice of turbulence and cavitation models is the key to investigate the cavitation in the microchannel by using numerical methods. Based on the Winklhofer microchannel fuel experiment, five representative turbulence models were used to construct a microchannel model, and the results were compared and analyzed with the experiment. The results show that the pressure gradient values obtained from the combination of RNG k-ε and ZGB models were similar to the experimental data, with an error of less than 6%. The cavitation distribution calculated from the combination of LES and ZGB models was most consistent with the experimental observation data. The outlet mass flow rate obtained from the LES and ZGB models matched the trend of the experimental data in the pressure difference range of 19 bar to 85 bar, with an error of less than 2%. For the cross-sectional flow rate calculation, the RNG k-ε and ZGB models had the smallest calculation errors, with errors below 11%. [ABSTRACT FROM AUTHOR]

A pump is needed in an ejector refrigeration system, which makes the system high cost and complicated and hinders its application. A pump-free double heat source ejector refrigeration system using R1234yf as working fluid is proposed in which an injector driven by another heat source replaces the liquid circulating pump, making the system more affordable, simpler and more stable. The effect of different operation conditions on entrainment ratios and the influence of different factors on system performance are analyzed on the basis of mass, momentum and energy conservation equations. The influence degree of each factor on system performance is investigated by the orthogonal test method. The condenser temperature has the largest effect on system performance. The pressure drop in the suction chamber of gas-liquid injector has the least impact on system performance. The COP can reach about 0.35 under a certain working condition. The system can be driven by two different temperature heat sources with no electricity needed, and it is a good choice for places with abundant heat resources or lack of electricity. [ABSTRACT FROM AUTHOR]

The treatment with partially removable prostheses has become more and more complex over time, especially in the last few decades. And when it is planned correctly, and executed responsibly, it will actually help preserve the remaining dental units. Consequently, performing the treatment in a defective manner, can trigger the resorption of the bone support and can accelerate the degradation of the remaining units, resulting in their loss.Elastic prostheses are the most modern alternative to injectable acrylic prostheses. The material is elastic, with a thinner thickness than conventional prostheses, resistant to pressure and dynamic movements during chewing, and very well approved from a biocompatible point of view by the tissues of the oral cavity. The reasons for choosing to treat partial edentulousness with partially removable elastic prosthesis are the feasibility and reliability of this.

Serial femtosecond crystallography (SFX) using an X-ray free electron laser (XFEL) enables the determination of room-temperature structures without causing radiation damage. Using an optical pump-probe or mix-and-injection, SFX enables the intermediate state visualization of a molecular reaction. In SFX experiments, serial and stable microcrystal delivery to the X-ray interaction point is vital for reasonable data collection and efficient beam time. The Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL) facility established SFX instruments at a nanocrystallography and coherent imaging (NCI) experimental station. Various sample delivery methods, including injection, fixed-target scanning, and hybrid methods, have been developed and applied to collect XFEL diffraction data. Herein, we report the currently available sample delivery methods for SFX at the NCI experimental station at the PAL-XFEL. This article will help PAL-XFEL users access the SFX system for their experiments.

Based on the solid–liquid two-phase flow model, SST k-ω model, and Lagrangian equation model of particle motion, numerical simulations of the sediment–water flow in the injector of a large Pelton turbine were conducted. The distribution rules of pressure, velocity, erosion rate, and erosion location of the injector were obtained by analyzing the sediment–water flow characteristics and sediment erosion distribution characteristics of the injector. The results revealed that the velocity distribution trend of the water inside the cylindrical jet exhibited a nonlinear distribution, and the phenomenon of “velocity deficit” occurred at the end of the needle guide and needle tip, resulting in a decrease in the jet quality of the injector. The sediment particle diameter affected the erosion rate of the needle and erosion location of the needle and nozzle port ring. This study provided guidance for sediment erosion analysis and the prediction of the utility of large Pelton turbines.