Inlet System Research Articles

Study of Application of PTFE Fiber in Self-cleaning Filter Media

To provide protection against the adverse effects of high concentration dust, self-cleaning filter was applied in the air inlet system of engine and gas turbine. PTFE fiber could have a great application in self-cleaning filter media due to its low surface free energy. In this work, new PTFE/cellulose fiber composite media for self-cleaning filter were prepared by wet-laid method. The effect of PTFE fiber on physical properties and filtration performance were studied. It was found that PTFE fiber was well dispersed in water without bubble formation after proper surfactant was applied. The initial figure of merit increased significantly when percentage of PTFE fiber was higher. For self-cleaning performance, particles were easier to be detached from composite media with higher PTFE fiber percentage, which resulted in lower average pressure drop. It was estimated that in the loading process, energy consumption of media containing 30 % and 60 % PTFE fiber was 32 % and 47 % less than that of pure cellulose media, respectively. PTFE fiber significantly improved the self-cleaning performance due to lower surface free energy of composite media and higher efficiency per unit thickness.

해수 유출입 시스템을 적용한 ballast-free 선형의 저항 및 추진 성능에 관한 연구

해수 유출입 시스템을 적용한 ballast-free 선형의 저항 및 추진 성능에 관한 연구

Numerical modelling of hydrodynamic and morphodynamic response of a meso-tidal estuary inlet to the impacts of global climate variabilities

Tidal inlets, a common feature along coastlines globally, can be significantly affected by the impacts of global climate variabilities. Computational models provide the best opportunity to assess future changes to the dynamics of inlet systems. In this paper, the morphodynamic response of a gravel-dominated meso-tidal estuary inlet to Sea Level Rise (SLR) is discussed based on three future SLR scenarios. It uses a process-based computational coastal area model. The study's test site is the meso-tidal Deben Estuary inlet in the UK; it is very morphodynamically active and has a unique sediment environment, is used as the test site of this study. The modelling results reveal that the morphological response of Deben inlet is sensitive to the SLR scenario. Rising sea levels give rise to increased hydrodynamic and morphodynamic activities at and around the inlet. The ebb delta, which is a prominent morphodynamic feature of this inlet, shows greater instability as a result of increased sea levels. It is possible that the inlet may deviate significantly from its current morphodynamic regime in the future as a result of the changes imposed by higher sea levels.

The use of Nafion membranes to measure 2H/1H and 18O/16O isotopic ratios in water

The isotopic composition of water (2H/1H and 18O/16O) has been widely used in hydrology, ecology, paleoclimatology and forensic science. However, sampling frequency limits many such studies and there is now a clear need for field-portable mass spectrometer and laser-based spectrometer devices to measure water isotopic composition in-situ and at high temporal resolution. Here we explore the use of Nafion membranes as a potential Membrane Introduction (MI) inlet system for high frequency isotope analysis. As yet, the fractionation behaviour of 2H/1H and 18O/16O isotopic ratios in water transported through Nafion membranes has not been investigated. We quantify this behaviour for water samples with different matrices (organic matter and pollutants) and salinity concentrations across a wide range of isotopic ratios and different membrane thicknesses. Nafion membranes showed no fractionation effects on reported isotope ratios for natural waters. Also no fractionation effects were detected with salinity. Membrane thickness affected slightly the precision and accuracy of the isotopic ratio analysis and our tests showed that thinner Nafion membranes provide better results. However, for samples contaminated with organic matter, the thicker membranes performed better for the 2H/1H isotopic ratio, while for samples contaminated with pollutants, the thicker membranes performed better for the 18O/16O isotopic ratio. Overall, Nafion membranes appear well suited to MI inlet use and our work suggests that the optimal Nafion membrane thickness is 50–150 µm.

Experimental Investigation of an Inverted Brayton Cycle for Exhaust Gas Energy Recovery

Exhaust gases from an internal combustion engine (ICE) contain approximately 30% of the total energy released from combustion of the fuel. In order to improve fuel economy and reduce emissions, there are a number of technologies available to recover some of the otherwise wasted energy. The inverted Brayton cycle (IBC) is one such technology. The purpose of this study is to conduct a parametric experimental investigation of the IBC. The hot air from a turbocharger test facility is used. The system is sized to operate using the exhaust gases produced by a 2 l turbocharged engine at motorway cruise conditions. A number of parameters are investigated that impact the performance of the system such as turbine inlet temperature, system pressure drop, and compressor inlet temperature. The results confirm that the output power is strongly affected by the turbine inlet temperature and system pressure drop. The study also highlights the packaging and performance advantages of using an additively manufactured heat exchanger to reject the excess heat. Due to rotordynamic issues, the speed of the system was limited to 80,000 rpm rather than the target 120,000 rpm. However, the results show that the system can generate a specific work of up to 17 kJ/kg at 80,000 rpm. At full speed, it is estimated that the system can develop approximately 47 kJ/kg, which represents a thermal efficiency of approximately 5%.

The development of the tidal basins in the Dutch Wadden Sea until 2100: the impact of accelerated sea-level rise and subsidence on their sediment budget – a synthesis

AbstractClimate change is very likely to cause a global acceleration in sea-level rise (SLR). The projected acceleration of SLR will also affect the Wadden Sea. In addition to an accelerated SLR, gas and salt extraction will cause subsidence that adds to an increase in water depth in the tidal basins. This will have consequences for the sediment budget of the Wadden Sea and especially for the intertidal flats that have a high ecological value. This synthesis presents projections of the future state of the Dutch Wadden Sea for the years 2030, 2050 and 2100.The projected changes in mean sea level by 2100 for Den Helder and Delfzijl are above the global mean projections, mainly due to the above-average ocean dynamics and glacio-isostatic adjustment contributions in the regional projections. The projected rise in mean sea level for 2100 with relation to 2018 in these locations is 0.41m, 0.52m and 0.76m for, respectively, the RCP2.6, RCP 4.5 and RCP8.5 climate scenarios.When we combine the presented SLR scenarios with the subsidence estimates and compare these rates to the critical rates for ‘drowning’ of intertidal flats that were calculated for the individual tidal basins, we can determine the moment that the maximum imported sediment volume can no longer compensate the increase in accommodation space in a basin and the intertidal flats will start to diminish in surface area and/or height. In the RCP2.6 scenario, the projected rates of relative SLR will be below the critical rate for drowning of the inlet systems in the Dutch Wadden Sea. For the RCP4.5 scenario, the critical SLR rate will be exceeded for Vlie Inlet in 2030, and for the RCP8.5 scenario the critical SLR rate will be exceeded for Vlie Inlet in 2030, Texel Inlet in 2050 and Ameland Inlet in 2100. For the other basins the critical rate will not be exceeded until 2100 or later.The way the intertidal flats in a basin will react to ‘drowning’ is not clear beforehand. It is highly possible that erosion of flats in one place will produce the sediment to maintain flats in other places. Tidal flats close to the sediment-delivering tidal inlet are not likely to disappear, because there the balance between supply and erosion is not likely to change.

Mechanistic study of reversible solid-state melt isomerization of 2-oxindoles to 2-quinolinones and its occurrence in a mass spectrometer

An eco-friendly equilibrated rearrangement of a series of 2-oxo-3-indolyl acetic acids (1) with 2-oxo-1,2,3,4-tetrahydroquinoline-4-carboxylic acid derivatives (2) was investigated through a solid state melt reaction (SSMR). Mechanistic insight into the thermal rearrangement is provided by 13C-isotopic labeling. The standard mass spectra of 1 and 2 were virtually identical preventing their reliable identification. Reversible interconversion of 1 and 2 was evidenced to occur in the inlet system of a mass spectrometer under electron impact conditions. Relative abundances of fragment ions were found to be a function of temperature.

Operation matching model and analysis between an air inlet and a compressor in an Air Turbo Rocket

Operation matching between an air inlet and a compressor in an Air Turbo Rocket (ATR) is crucial to the full development of the advantages of engines. In this study, operation characteristic models of an air inlet and a compressor were established and verified through numerical simulation to gain the matched operation characteristics of the air inlet and the compressor in an ATR. The air inlet–compressor matching model was constructed on the basis of coupling relations, such as “flow equilibrium,” “interface parameter equilibrium,” and “pressure ratio equilibrium,” between the air inlet and the compressor in the ATR. Finally, the integrated 3D numerical simulation of the air inlet–compressor was verified. Results demonstrate that (1) the operation characteristic model of the air inlet can accurately calculate the effects of backpressure in the air inlet (Pb) on the total pressure recovery coefficients of the throat, the supersonic diffuser, and the whole air inlet in the ATR. Model prediction results are highly accurate as confirmed by 3D numerical simulation results in the following ranges: 2.75 < Ma < 3.75 and 0.5 atm <Pb < 3 atm. The maximum absolute error is less than 0.05. (2) The centrifugal compressor model can indicate the airflow and performance parameters of different characteristic sectors of impeller entrance, compressor exit, and axial diffuser entrance and exit. The 3D numerical simulation reports that the maximum relative errors of static pressure, total pressure, and total temperature predictions are 13.25%, 11.30%, and 5.65%, respectively. (3) The constructed air inlet–compressor matching model can rapidly predict the airflow parameters and performance parameters of their characteristic sections under specific operation conditions. The “most stable operation curve” introduced in the pressure ratio characteristic curve of the compressor can quickly and accurately accomplish the initialization of matching iterative computations, thereby solving aerodynamic coupling problems on an air inlet–compressor interface. (4) The integrated 3D numerical simulation of the air inlet/compressor reveals that the relative errors of 17 in 18 airflow parameters of two components are lower than 8%, and the relative error of the other parameters is 10.91%. The model exhibits high accuracy and can satisfy the requirements for the performance prediction of air inlet systems in ATR.

An approach to an optimal T-head jetty: a numerical simulation case in Chamela Bay, Mexico

ABSTRACTA mathematical optimization problem is analyzed to obtain the most suitable T-head jetty design in an artificial tidal inlet system. In this study, the T-head jetty is considered optimal when two constraints are satisfied, specifically (1) the velocity of the currents and (2) the turbulence generated by the flow, both are minimal. These constraints are assessed in a control region around the inlet. To resolve the mathematical optimization problem, the hydrodynamic model Delft3D was combined with a derivative-free optimization method, the Nelder–Mead method. The effectiveness of this methodology was tested in a series of numerical experiments made at Chamela Bay on the Mexican Pacific Coast, where it is planned the construction of an artificial channel to connect the bay with a coastal lagoon. With this approach, future negative effects might be analyzed and reduced before modifying this pristine bay.

One-dimensional univariate work simulation of turbocharged engine with restrictor before compressor inlet

All over the world, and in Russia, especially, the engineering sports competitions "Formula Student" are gaining popularity. Formula Student - is an international competition held among students of technical universities, in order to get practical knowledge in the process of developing and building a Formula student class racecar. When creating a car, you must adhere to strict technical regulations. So, one of the limitations is the maximum engine capacity - 710 cubic meters, which, in itself, implies the use of a motorcycle engine. A mandatory condition is the presence of a restrictive nozzle (restrictor) which have 20 mm diameter and placing in the inlet system. This causes many problems when designing engine intake systems. However, it allowed using various systems of pressurization of engines. The most common and effective is the installation of the turbocharger. This helps to solve the problem of insufficient amount of air that entering to the engine. Moreover, with the correct configuration of all components of the intake system in combination with the turbocharger, it is possible to achieve power and torque exceeding the standard engine without a restrictive nozzle. The article presents the data obtained in the course of a one-dimensional simulation of the KTM LC4 engine with a turbocharger and a restrictor in the intake manifold. The purpose of the work is to reduce the negative influence of the restrictor on the power and torque parameters of the KTM LC4 engine by using a turbocharger. In the course of the work, an analysis was made of gas-dynamic processes occurring in various parts of the engine intake system that affect its output values based on numerical studies. Because of the research, the dependences of the output parameters of the engine (maximum power and maximum torque) on the parameters, shapes and sizes of various components of the intake system with a turbocharger.

Investigating the Stability of Double-Inlet Tidal Systems Using a Process-Based Modelling Approach

Dastgheib, A.; Wulandari, A.S.R., and Ranasinghe R., 2018. Investigationg Stability of Double-Inlet Tidal System Using a Process-Based Modelling Approach. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 161–165. Coconut Creek (Florida), ISSN 0749-0208.Tidal inlet systems provide a dynamic connection between the ocean and water mass behind their barriers and are subjected to human intervention and natural changes. An understanding of the dynamic processes in tidal inlet systems is important for decision makers managing these areas. Most previous studies are focused on a basin connected to the ocean via a single inlet. But multi-inlet systems have more complexity than the typical single-inlet system, especially considering the interaction among different inlets. In this study, following the realistic analogue approach, we have adopted a morphodynamic process-based model (Delft3D) as a numerical lab and set up a model for a schematized double-inlet tidal system to investigate the stability of such systems. We have carried out a series of simulations and systematically changed the width and initial depth of the inlets and also the amount of sediment coming to the inlet due to littoral drift along the coast. Based on the result of these simulations, first, we developed “Escoffier” type stability curves for each inlet in every simulation. In the second step, we have fixed the cross-sectional area of one inlet and allowed the second inlet to evolve. We used the results of this set of the simulations to develop a 3D stability “Escoffier” curve as a function of the cross-sectional areas of both inlets and equilibrium velocity and identified stable and unstable equilibrium conditions. In the third step, to test these equilibrium points, we altered the stable system in seven different ways to show that the system goes back to one of these equilibrium conditions.

Exergoeconomic assessment and optimization of a syngas production system with a desired H2/CO ratio based on methane tri-reforming process

Based on methane tri-reforming process, a novel syngas producing system is proposed. The proposed system is analyzed in details from the viewpoints of thermodynamics and economics. In order to calculate the reactor volume required for its cost evaluation, a one dimensional homogenous model, based on the chemical kinetics of tri-reforming reactions is conducted for a fixed bed reactor.Influence of some design parameters including the reactor inlet temperature, system pressure, feed composition and reactor length on the reforming process as well as on the system performance is examined. Then, an optimization process is performed to maximize the overall energy efficiency. The results of parametric study demonstrate that the main indicators of system including H2 yield, H2/CO ratio, CH4 and CO2 conversions, energy efficiency and unit cost of the produced syngas are enhanced at thermodynamic conditions of high temperatures and low pressures. It is observed that, when the H2O concentration in the feed composition increases or the CO2 concentration decreases, the unit cost of produced syngas is reduced. In addition, the optimization process yields a maximum overall energy efficiency of 92.46 %. At this optimum design point, the unit cost of produced syngas is calculated as 4.48 $/GJ. Moreover, it is revealed that close to the reactor entrance, all oxygen is consumed by the methane combustion and the mixture temperature increases rapidly to a maximum value.

Volumetric Efficiency Optimization of Manifold with Variable Geometry Using Acoustic Vibration for Intake Manifold with Variable Geometry in Case of LPG-Enriched Hydrogen Engine

A proper design of the engine intake system can provide the best engine performance. The modeling of inlet system is very important for the evaluation of the engine performance. It is known that the wave dynamics of intake system influences the engine performance. In the present work, the acoustic supercharging phenomenon is applied to optimize the volumetric efficiency of an engine converted into LPG–hydrogen blend. The effect of the intake plenum length on the engine performance is investigated. In fact, an analytical resolution of acoustic waves is used to perform the optimal length for several engine speeds. This resolution is based on the impedance method. In a second step, a simulation of the pressure wave evolution in the intake pipe is carried out using the method of characteristic in order to validate the lengths analytically found. After that, a validation is achieved through experimental data. The results showed that an optimum length calculated by the analytical method gives a maximum in-cylinder velocity (0.649 m at 750 rpm and 0.696 m at 1000 rpm).

Determining the Contribution of Ventilation and Insulation of Broiler Breeding Houses in Production Performance Using Analytic Hierarchy Process (AHP)

ABSTRACT This study was conducted using Analytic Hierarchy Process (AHP) in order to rank broiler breeding farms in Zanjan province, Iran, regarding buildings, installations, and equipment to determine their effects on production factors. Data on 108 farms were collected using designed forms. This data was analyzed based on the effectiveness of each parameter in the production and management category according to experts’ opinion. The results indicated that ventilation systems (fans, inlets, and damper) as well as wall and roof insulation in poultry houses, constituted 66% of the technology coefficient. The stocking density increased through improvement of the mechanization coefficient. Most of these farms used longitudinal or tunnel ventilation and a combination of small and large fans. Roof insulation was mostly done using glass wool, and corrugated plastic while installing the heaters outside the poultry house. In these farms, the use of nipple drinkers and plate feeders was more prevalent. Moreover, the results showed that feed conversion and production indices have a significant correlation with mechanization coefficient so that farms with better mechanization coefficients had lower conversion ratio (p=0.04) and higher production indices (p=0.015). In general, the results indicated that ventilation and air inlet systems, as well as wall and roof building technologies have the greatest influence on the mechanization coefficient, while better mechanization coefficients translated into improvements in production efficiency and economic performance of poultry farms.

Aeroelastic Study of the Splitter Plate in Turbine-Based Combined-Cycle Inlet

A two-dimensional over–under turbine-based combined-cycle inlet system that exhibits the fluid–structure interaction phenomenon is investigated at both design and off-design states. The mesh-based parallel code coupling interface is used to perform a two-way loosely coupled data exchange across the fluid–structural interfaces. Results indicate that, although the performance variation is limited at a ramjet mode with , unexpected limit cycle oscillations appear accompanied by unsteady amplitudes. Moreover, a remarkable unstart delay along with the deceleration process of performance deterioration can be observed when the backpressure goes through a rapid increase, where the upward deformation of the splitter plate plays a significant role in resisting the downstream disturbance. In contrast, the fluid–structure interaction effect leads to an earlier occurrence of inlet unstart when the angle of attack varies periodically, and it induces limit cycle oscillations at a higher varying frequency. The study reveals the necessity of attaching more importance to the aeroelastic behavior of the splitter plate in the future research and operation of the over–under turbine-based combined-cycle inlet system.

The gas supply and gas inlet control systems of the fusion experiment Wendelstein 7-X

After a detailed commissioning process the fusion experiment Wendelstein 7-X (W7-X) was ready to operate in December 2015. The gas supply system and the gas inlet system are two important technical systems of the W7-X device, offering a wide spectrum of functions for plasma vessel conditioning, and plasma operation as well as for diagnostic and calibration purposes.A brief overview is given of the structure of both gas supply and gas inlet systems. The design of the control systems of the gas supply and the gas inlet are introduced and described. The application of the W7-X gas inlet system is explained during an experiment discharge.

Enabling real-time detection of electrochemical desorption phenomena with sub-monolayer sensitivity

Electrochemical reactions play an increasingly important role in sustainable energy conversion and chemical synthesis. Better understanding of catalytic mechanisms at electrode surfaces is thus important for the transition to a clean-energy economy, but is hindered by the difficulty of real-time detection of reaction products and intermediates during electrochemistry experiments. Herein, we present a new type of electrochemistry – mass spectrometry (EC-MS) based on a versatile gas inlet to vacuum fabricated onto a silicon microchip, and compare it to established techniques with focus on sensitivity, time response, and mass transport. The inlet system is able to capture reactant molecules directly from an electrode surface and pass them on to a mass spectrometer on a sub-second time scale with 100% collection efficiency for quantitative analysis with unprecedented sensitivity. The high sensitivity and fast time-response, coupled with well-characterized mass transport of both reactants and products in this setup enables sub-turnover resolution for analysis of electrochemical reactions. The technology and concepts presented here can serve as a platform to improve in-situ mass spectrometry in electrochemistry as well as other fields.

Effect of functional solutions applied in machinery on fuel consumption and emissions

Because stricter norms of emission of hazardous substances are being introduced every few years, machinery manufacturers are also forced to introduce various modifications to reduce emissions. To this end, systems aimed at optimising the process of fuel combustion and reducing the amount of hazardous compounds are being applied. Three tractors used in agriculture, with various functional solutions, were examined in this study. The effect of various systems on reduction of hazardous emissions and fuel consumption was determined. The tests were conducted during the ploughing with a 4-bottom swivel plough. The effect of the selective reduction (SCR) system with AdBlue liquid, the exhaust gas recirculation (EGR) system, the particulate filter, the number of valves per cylinder and the type of a turbocharger in the engine’s inlet system were determined. It was observed during the tests that there were differences in fuel consumption and emissions depending on the constructional solutions applied in the tractors.

Upgrading the ECR ion source within FAMA

Recent upgrading of the Facility for Modification and Analysis of Materials with Ion Beams - FAMA, in the Laboratory of Physics of the Vinca Institute of Nuclear Sciences, included the modernization of its electron cyclotron resonance ion source. Since the old ion source was being extensively used for more than 15 years for production of multiply charged ions from gases and solid substances, its complete reconstruction was needed. The main goal was to reconstruct its plasma and injection chambers and magnetic structure, and thus intensify the production of multiply charged ions. Also, it was decided to refurbish its major subsystems - the vacuum system, the microwave system, the gas inlet system, the solid substance inlet system, and the control system. All these improvements have resulted in a substantial increase of ion beam currents, especially in the case of high charge states, with the operation of the ion source proven to be stable and reproducible.

A novel atmospheric tritium sampling system

The health hazard of tritium is related to its chemical form. Sampling different chemical forms of tritium simultaneously becomes significant. Here a novel atmospheric tritium sampling system (TS-212) was developed to collect the tritiated water (HTO), tritiated hydrogen (HT) and tritiated methane (CH3T) simultaneously. It consisted of an air inlet system, three parallel connected sampling channels, a hydrogen supply module, a methane supply module and a remote control system. It worked at air flow rate of 1 L/min to 5 L/min, with temperature of catalyst furnace at 200 °C for HT sampling and 400 °C for CH3T sampling. Conversion rates of both HT and CH3T to HTO were larger than 99%. The collecting efficiency of the two-stage trap sets for HTO was larger than 96% in 12 h working-time without being blocked. Therefore, the collected efficiencies of TS-212 are larger than 95% for tritium with different chemical forms in environment. Besides, the remote control system made sampling more intelligent, reducing the operator’s work intensity. Based on the performance parameters described above, the TS-212 can be used to sample atmospheric tritium in different chemical forms.