Chamber Inlet Research Articles

Information technologies for the study of the planned and profile model of the flux creep in the transit channel

The article presents the inlet chamber computer models for the Beloyarskyin take structure: a computer model of the depth distribution and a computer model of the water level distribution for determining the hydrodynamic structure of the flux creep in the transit channel. To build a computer model, the depth survey of the inlet chamber was used during hydro meteorological surveys. The water level at the survey time is 15.30 m. The construction of a depth distribution computer model in the inlet chamber at the intake structure for the water supply of the Beloyarsky city was carried out by the finite element method on a personal computer in the Multiphysics software product. The uneven distribution of average velocities on the verticals, both along the channel width and length, is explained by the significant expansion of the inlet chamber in the intermediate sections 2-2, 3-3, 4-4, 5-5 in relation to the input 1-1 and output sections. Deepening the channel in the entrance section 1-1 by an average of 1.3-1.5 m will increase its flow rate to 10, 2m3/s or 10 times with an increase in the average speeds on the verticals by 2.0-2.5 times. Such an increase in the flow rate in the input section will lead to an increase in the average speeds in other sections 2-2, 3-3, etc. Hence, the passage of increased flow through the transit channel after clearing a number of shallow areas will create better conditions for preventing algae spread.

Analysis of the partially premixed combustion in a labscale swirl-stabilized burner fueled by a methane-hydrogen mixture

Nowadays hydrogen is gaining more and more attention by Industry, Academia and Politics. Being a carbon free fuel, it is supposed to have a key role in the future energy scenario, especially if produced by renewable sources. The use of mixtures of hydrogen and conventional hydrocarbons in gas turbines is one of the most promising technical solutions for obtaining a sustainable combustion during the transition toward a full decarbonization. For this reason, it is fundamental to investigate the behaviour of fuels enriched with hydrogen in combustion processes. In this work, a lab-scale swirled premixed burner has been investigated by means of a fully 3D URANS approach. Firstly, a numerical simulation with cold flow has been performed to validate the model against experimental data. Then, reactive flow simulations have been performed. Initially, a combustion with 100% methane was considered. Then, a 30% by volume hydrogen blending has been investigated. The partially premixed combustion model has been implemented to take into account the inhomogeneities of the mixture at the chamber inlet. The variation of the flame structure due to the hydrogen enrichment will be described in terms of the temperature and species concentration distributions.

ВОДОЗАБОР ИЗ ПОВЕРХНОСТНОГО ВОДНОГО ИСТОЧНИКА ДЛЯ РЫБОВОДНО-МЕЛИОРАТИВНЫХ КОМПЛЕКСОВ

Purpose: development of a layout-design solution for water intake from a surface water body, excluding the entry of harmful aquatic organisms into fish-breeding reservoirs. In accordance with modern ideas about water intakes that meet the requirements of fish protection and prevent the ingress of aquatic organisms into water supply system of fish-breeding complexes, filtering water intakes are the most effective. Materials and Methods. The water intakes structures development is based on the materials of the fish and water body surveys and the results of the analysis of developments in this area. Results. As part of water nutrition system of the fish-breeding complex, it is proposed to use a water intake with a two-chamber water inlet equipped with filtering panels and regulating screens. Filtering panels located at the head of each of the chambers ensure the retention of harmful, weed and predatory aquatic organisms, and the screens ensure the water inlet shutdown at replacing the filtering panels. Various modes of water inlet chambers operation are considered for intake of various water flows, replacement of filter cassettes and shutdown of water intake operation. It is proposed to use a filtering panel with impervious chambers, which make it possible to simplify the cleaning of its filler as a filtering element. Conclusions. A layout solution for a filtering water intake as part of water nutrition system of the fish-breeding complex has been proposed and developed. The design of a two-chamber water intake based on the use of filter panels and impervious screens, providing fish protection functions and preventing harmful, weed and predatory species of aquatic organisms from entering the water supply system is developed. A technology for water inlet functioning under various operating modes of the water intake has been developed. It is proposed to use a filtering panel with a simplified scheme for cleaning it from colmatation products as a water inlet element of the water intake.

Numerical and experimental investigations on non-axisymmetric D-type inlet nozzle for a squirrel-cage fan

ABSTRACT In this study, the unique reverse-flow around the inlet nozzle of a squirrel-cage fan was numerically studied by computational fluid dynamics (CFD), and a non-axisymmetric D-type inlet nozzle was proposed to inhibit it. It is shown that serious back flow develops at the volute tongue when the fan operates at a low flow coefficient that is lower than the best efficiency point. The airflow passing the blade passages in reverse further crosses the impeller, mixing the clearance leakage airflow, and finally blows into the intake chamber near the circumferential position of . By installing the inlet nozzle along this direction, D-type inlet nozzle schemes with different blockage extent were calculated by CFD. The scheme with a cut distance of 70% of its exit-section radius was chosen as the best design by comprehensively comparing the back flow ratio and fan performance of different working conditions. CFD results illustrated that reverse blowing at the fan entrance was significantly constrained by this D-type inlet nozzle, and the vortex in the inlet chamber correspondingly disappeared. Experimental data illustrated that the new nozzle increased the fan pressure rise under low-flow conditions by about 6% and barely reduced performance at other working points.

Numerical Investigation of Centrifugal Compressor Radial Inlet

Efficient compressors designs reduce the overall energy consumption of industrial buildings. The inlet chambers for turbocompressors have a significant influence on the whole stage operation. An uneven flow in the inlet of an impeller can turn up to be the cause of stage efficiency drop, and also it is able to narrow down the range of its operational stability which in turn is an essential negative factor. Currently, there is no clear methodology of the design of the inlet radial chambers which makes it difficult to design the compressor. The purpose of this work is to develop recommendations for the designing problem formulation of the centrifugal compressor radial inlet chamber and also modify the existing design method for inlet chambers. During the previous research, the most acceptable model of the inlet chamber was obtained with the help of real and numerical experiment. In this paper, different geometric parameters of the inlet chamber are changed and then calculated by means of numerical experiment. Their influence on the inlet chamber loss coefficient, relative velocity distribution and static pressure coefficient is investigated.

Numerical modeling of core compressor discharge for a windmilling aero engine

A gas turbine engine's ability to relight in flight depends heavily on the combustion chamber's inlet conditions. These conditions are dictated by the core compression system located immediately upstream of the combustor, but such conditions during windmill have not been thoroughly investigated and are not commonly available in the literature. In this paper, an entire high pressure ratio axial compressor is modeled using scale adaptive simulation. Real windmilling inlet conditions extracted from altitude test facility data are used as boundary conditions. The implications of steady vs. unsteady modeling and the use of different interface modeling approaches are investigated. A description of the discharge flow-field is given in terms of flow statistics, turbulent quantities, and dominant dynamic modes. The discharge flow-field is dominated by small scale structures resulting from leading edge separation in the last stator (OGV), with little influence of the upstream stages on the stator flow-field dynamics. The study has shown that, while an unsteady analysis is required, reduced order models allowing for a decoupled analysis of the last stage flow dynamics may be sufficient in future studies seeking to characterize combustor inlet conditions for inflight relight.

Numerical study on the auxiliary entrainment performance of an ejector with different area ratio

In this paper, an ejector-based multi-evaporator refrigeration system is proposed for the tropical region refrigerated trucks. CFD simulations are performed to study the auxiliary entrainment effect of the ejector operated in air-conditioning - freezing mode. First, the performance of the ejector with various auxiliary hole position in different chambers is investigated. Then, based on the optimal auxiliary hole position of each chamber, the influence of double and triple auxiliary holes on the ejector performance is identified. Next, optimal angle with the optimized auxiliary hole position is determined. Last, the effect of the ejector area ratio on optimal auxiliary hole position, angle and entrainment ratio is evaluated. The main results show that: (1) Optimal auxiliary hole position is 59.5 mm or the length ratio of distance between the inlet of constant-area mixing chamber and the auxiliary hole center point to the length of the constant-area mixing chamber is 1.90, and optimal auxiliary hole angle is 45°; (2) The effect of the auxiliary hole position on the ejector performance is stronger than the auxiliary hole angle; (3) the optimum auxiliary hole position, angle as well as entrainment ratio are affected by the ejector area ratio.

Design and Fabrication of a Plastic Biogas Digester for the Production of Biogas from Cow Dung

Biogas digester dimensions and materials of construction are important factors of consideration during the design and fabrication phase. The aim of this study is to provide a detailed analysis of the design and fabrication of a 2.15 m3 pilot plastic biogas digester for biogas generation. To establish this, a design equation covering the volume of the digester, inlet and outlet chambers, and digester cover plate were developed considering the shape of the digester. The digestion chamber of the biogas digester under study was fabricated using high-density polyethylene (HDPE) plastic, while the inlet and outlet chambers were constructed with bricks/cement. The study was motivated due to some limitations such as leakage associated with previous designs. In the present study, a ventilation test was conducted after the fabrication to ensure the digester is leak free. Results obtained showed a total volumetric methane gas yield of 2.18 m3 (54.50%) and carbon dioxide yield of 1.77 m3 (44.25%) making up a total biogas yield of 4.00 m3. In addition, the percentage concentration of methane and carbon dioxide were found to be 60% and 30%, respectively. The developed plastic biogas digester has been found to be appropriate for biogas production using cow dung as substrate.

Numerical and experimental analysis of heat and mass transfer in the drying process of the solar drying system

Design in a solar food drying system is crucial for food drying performance. In order to make effective use of the sun, the use of air-heated solar collectors is gradually increasing in drying systems. Dryer room temperature and pressure distribution modelling is a very important factor for system design and product selection. In this study, the drying air speed, drying temperature, and product moisture content values of a solar drying system were numerically modelled in a time dependent manner. In numerical analysis, temperature and drying air velocity were defined as variable under initial and boundary conditions. Polynomial equations based on time obtained from drying room inlet temperature and drying air velocity data were used. The R2 values of these equations were calculated as 0.96 and 0.91, respectively. COMSOL multiphysics program was used for temperature values, drying air velocity, product moisture content values and drying chamber pressure values modelling. Depending on the position of the sun and the time, the drying chamber inlet temperature values and air velocity values have been change. During the drying process of the product, moisture content values, heat and mass transfer values, drying efficiency values, diffusion coefficient and activation energy values were examined. Experimental data and computed fluid dynamics analysis (CFD) data were compared. Using the CFD numerical analysis program, the drying room temperature, moisture content and air velocity values were modelled with mean absolute percent error (MAPE) of 5.34%, 3.74% and 6.30%, respectively.

Combustion Stability Analysis of Liquid Biofuels using Acoustic Signals

Biodiesel and vegetable oil suffer from higher viscosity and boiling point resulting in poor atomization and evaporation rate compared to diesel fuel additional to the lower heating value which negatively affect the stability of flame. The unsteady heat release rate from flame provides unique pressure wave signature that can be captured as acoustic wave. A pressurized combustion chamber was developed and connected to a vehicular turbocharger to test combustion stability and emissions of wide range of liquid biofuels. Biodiesel and blends of palm oil/diesel from 10% (Vol.%) up to 100% pure palm oil (i.e. P10-P100) were investigated and compared to diesel as the benchmark fuel. Microphone probes at the chamber inlet and outlet were used to capture the acoustic signals to be analyzed through the Fast Fourier Transform (FFT) using MATLAB program. The analysis of the acoustic signals revealed distinguishable deviation patterns between diesel and other biofuels which showed close resemblance to the carbon monoxide (CO) emission patterns at the same operating pressures. Biodiesel was comparable to P20, while increasing palm oil blend resulted in higher deviation. Chamber pressure also showed positive effect on combustion stability and reduced the deviation between diesel and other biofuels.

A novel microfluidic chip-based sperm-sorting device constructed using design of experiment method

Microfluidics is proposed as a technique for efficient sperm sorting, to achieve the ultimate goal of resolving infertility problems in livestock industry. Our study aimed to design a microfluidic sperm-sorting device (SSD) through a high-efficacy and cost- and time-effective fabrication process, by using COMSOL Multiphysics simulation and modeling software, and the design of experiment (DOE) method. The eight factors affecting SSD performance were established. The simulation was then run, and statistically significant factors were analyzed. Minitab16 was used to optimize the design modulus factor. By setting the statistical significance at p < 0.05, the factors affecting experimental structure were analyzed. At a desirability of 97.99, the optimal parameters for the microfluidic chip were: angle between sperm and medium inlet chambers (A = 43°), sperm inlet flow rate (B = 0.24 µL min−1), medium inlet flow rate (C = 0.34 µL min−1), and inlet and outlet chamber lengths (D = 5000 µm). These optima were then applied to microfluidics device construction. The device was produced using soft lithographic microfabrication techniques and tested on Holstein–Friesian bull sperm. The highest bull sperm-sorting performance for this microfluidic device prototype was 96%. The error between the simulation and the actual microfluidic device was 2.72%. Fluid viscosity ranges analysis-based simulations revealed acceptable fluid viscosity tolerances for the SSD. The simulation results revealed that the acceptable tolerance range for fluid viscosity was 0.00001–0.003 kg m−1 s−1. This optimally designed microfluidic chip-based SSD may be integrated into sperm x/y separation micro devices.

Methane transport in a soil column: experimental and modeling investigation

This study explored two diffusion approaches, Fick’s law and the dusty gas model (DGM), to assess their differences on modeling methane transport in porous systems. Laboratory experiments were also conducted for methane transport through a nitrogen gas-dry soil column from different source densities. Gas pressures and methane densities at transient state were measured along the column for two transport configurations (horizontal and vertically upward) and compared with the predictions obtained from the DGM- and Fickian-based models. The retardation factor is the only parameter used in the model calibration. The results showed that the methane density profiles predicted by these models fairly matched the measured data and are quite consistent for vertically upward transport of methane. However, the predictions were over the measured ones for horizontal transport of methane. We suspected it is due to incomplete mixing of gas mixture in the inlet chamber since high pressure variations were observed in the horizontal transport experiments. Further, we found that the methane density profile predicted by the Fickian-based model is lagged behind the DGM result for at most 15% of difference in methane density for horizontal transport of methane from a pure methane source.horizontal transport experiments. Further, we found that the methane density profile predicted by the Fickian-based model lagged behind the DGM result for at most 15% of difference in methane density for horizontal transport of methane from a pure methane source.

Fast and Accurate Core Analysis by the Full-Immersion Pressure-Pulse Decay: Part 1—Theory

Summary Core-scale measurements are considered the ground truth that oil and gas or electric utility companies use to predict the migration of fluids such as oil, natural gas, carbon dioxide, or brine deep underground during their extraction or injection operations. To provide a greater understanding of petrophysical properties of low-permeability geologic formations such as shales and tight gas sandstones, this study introduces a novel core-analysis procedure. The technique follows conventional pressure-pulse-decay permeametry, where the pressure in an inlet chamber adjacent to a cylindrical core plug undergoes a rapid pressurization, the system is shut in, and the pressure reaches a new equilibrium. However, unlike a standard unidirectional pressure-pulse decay, the full-immersion pressure-pulse decay (Hannon 2019) applies a pressure disturbance to the entire outer surface area of the sample. This article covers the numerical simulator designed to model flow through an anisotropic porous sample in this scenario. The model assumes distinct but uniform permeabilities along the radial and axial directions of the cylindrical plug sample. When extracting a plug vertically (or perpendicular to bedding), the permeability along the radial direction associates with the horizontal permeability (i.e., parallel to bedding), whereas in the axial direction, flow occurs perpendicular to bedding (a vertical permeability). Investigations of these model outputs demonstrate an approximately 20-fold decrease in time to complete a full-immersion experiment compared with conventional pressure-pulse decay. Furthermore, the pressure-decay curves resulting from the full-immersion method have slightly different shapes than those resulting from other unidimensional transient methods. These differences begin to demonstrate that, under achievable experimental conditions, the analysis of pressure data from one full-immersion test could enable the simultaneous estimation of the apparent permeabilities parallel and perpendicular to bedding of a cylindrical sample in addition to its porosity. A follow-up article finalizes the proof of this capability with a parameter-estimation procedure and presents experimental verification through a proof-of-concept study. Described in greater detail in that article, the parameter estimator requires multiple forward simulations to analyze the data, which behooves minimizing the compute time for each simulation. By using an alternating direction implicit time-marching scheme and a structured but variably spaced grid, the numerical simulator built for this purpose provides a forward model output with suitable accuracy in approximately 0.5 seconds.

Study on Effects of Inlet Resistance on the Efficiency of Scroll Expander in Micro-Compressed Air Energy Storage System

As an important part of a micro-compressed air energy storage system, the scroll expander directly affects the efficiency of the whole energy storage system. The effects of resistance on the efficiency of scroll expander caused by inlet structure and size are discussed with theory analysis and experimental methods in this paper. Micro-compressed air energy storage system has aroused widespread attention because of its pollution-free, high flexibility, in the community, remote areas power supply. Comprehensive experimental work with the selections of different size and structure of the air inlet of the scroll expander was performed with the cutting angle of air inlet chamber of the scroll expander. The results of the experiments are discussed on how exergy efficiency and inlet flow of the scroll expander were affected resulting from the cutting angles dissected. The results show that a maximum value exists for exergy efficiency of the scroll expander. Therefore, the exergy efficiency of the scroll expander can be effectively improved by enlarging the air inlet port dimension and modifying the size of air chamber.

Optimizing Secondary Electrospray Ionization High-Resolution Mass Spectrometry (SESI-HRMS) for the Analysis of Volatile Fatty Acids from Gut Microbiome.

Gut microbiota plays essential roles in maintaining gut homeostasis. The composition of gut microbes and their metabolites are altered in response to diet and remedial agents such as antibiotics. However, little is known about the effect of antibiotics on the gut microbiota and their volatile metabolites. In this study, we evaluated the impact of a moderate level of ampicillin treatment on volatile fatty acids (VFAs) of gut microbial cultures using an optimized real-time secondary electrospray ionization coupled with high-resolution mass spectrometry (SESI-HRMS). To evaluate the ionization efficiency, different types of electrospray solvents and concentrations of formic acid as an additive (0.01, 0.05, and 0.1%, v/v) were tested using VFAs standard mixture (C2–C7). As a result, the maximum SESI-HRMS signals of all studied m/z values were observed from water with 0.01% formic acid than those from the aqueous methanolic solutions. Optimal temperatures of sample inlet and ion chamber were set at 130 °C and 85 °C, respectively. SESI spray pressure at 0.5 bar generated the maximum intensity than other tested values. The optimized SESI-HRMS was then used for the analysis of VFAs in gut microbial cultures. We detected that the significantly elevated C4 and C7 VFAs in the headspace of gut microbial cultures six hours after ampicillin treatment (1 mg/L). In conclusion, our results suggested that the optimized SESI-HRMS method can be suitable for the analysis of VFAs from gut microbes in a rapid, sensitive, and non-invasive manner.

A new experimental setup for measuring greenhouse gas and volatile organic compound emissions of silage during the aerobic storage period in a special silage respiration chamber

The aim of this study was to develop a new experimental setup to determine parallel the emissions of greenhouse gases (GHG) and volatile organic compounds (VOCs) from silage during the opening as well as the subsequent aerobic storage phase of the complete bale without wrapping film. For this purpose, a special silage respiration chamber was used in which a silage bale could be examined. The gas analysis (CO2, methanol, ethanol, ethyl acetate) of inlet, ambient and outlet air of the silage respiration chamber was carried out by photoacoustic spectroscopy. The gas samples taken inside the bale were analysed by gas chromatography for CO2, O2, CH4, and N2O. Three silage bales (grass and lucerne) as the smallest silage unit commonly used in practice were examined. The emission behaviour of the bales was recorded during experimental periods up to 55 days. The results allow a differentiation of the outgassing processes. On the one hand, gases produced during the anaerobic ensiling process (CO2, CH4, N2O) are released once in a large amount during the first experimental hours after opening the silage. On the other hand, a continuous outgassing process takes place, which is particularly true for the VOCs ethanol, methanol, and ethyl acetate, whereby VOC emissions increase with rising ambient air temperatures. In this study, the emissions during the first 600 experimental hours from the grass silage bale and lucerne silage bale were 2313 g and 2612 g CO2, 17.6 g and 145.2 g methanol, 132.3 g and 675.9 g ethanol, 55.1 g and 66.2 g ethyl acetate, respectively. Nevertheless, the focus of this study was on the technical recording of gas concentrations inside the silage bale itself and the emissions in the ambient air of the bale. For a better interpretation of the data, additional factors should be considered in further investigations.

Rippled scales in a geothermal facility in the Bavarian Molasse Basin: a key to understand the calcite scaling process

Mineral precipitates, scales, are wide-spread in geothermal facilities and hamper technical and economic efficiency. Scales reported from earlier studies in the Bavarian Molasse Basin consisted mostly of calcite, appeared rather homogeneous, grew flat and perpendicular to the surface, and showed little or no internal macrostructure apart from small gradients in crystal size and chemical composition. In this study, we investigated extraordinary calcite scales collected from the inlet chamber of a heat exchanger. These scales showed current ripples and a sequence of coarse and dense layers. By an extensive investigation of the ripples, the hydrochemistry, and by the application of existing empirical equations, the formation of the ripple scales could be reconstructed: Due to degassing of {text {CO}}_{2} in the geothermal pump calcite scales precipitated on the pipes of the ground-level facilities. During maintenance works, these scales were partially dissolved, and remobilized as individual mobile grains. These particles subsequently settled again, and solidified as ripple scales in the horizontal pipes at surface level. For this ripple forming process, flow had to be small, because otherwise the ripples would have been altered or washed away. After deposition of the ripple structure, a dense new calcite layer precipitated on top of the ripples, and stabilized it due to transitory supersaturation. This sequence of ripples and a dense calcite cover layer is repeated two times. Finally, during start-up of regular plant operation, the whole composite scale was remobilized and got washed into the inlet chamber of a heat exchanger. The investigation presented here indicates that this type of calcite scale only forms in geothermal facilities in the Bavarian Molasse Basin if certain flow and hydrochemical conditions are present during the maintenance procedure.

Experimental study on wave-structure interaction of an offshore intake well with a curtain wall

ABSTRACT The present study focus on the wave-structure interaction of a caisson type offshore intake well with the regular waves. A 1:20 scale model is experimentally investigated with and without curtain wall in the shallow wave basin for its hydrodynamic responses like wave run-up, rundown, and free surface water oscillation inside the well. The wave run-up and rundown on all the faces record maximum when the scattering parameter (ka) is minimum. Moreover, the increase in relative wave height (H/d) results in an increase in the run-up on the seaward and shoreward faces. Besides, the free surface oscillation at the inlet and pumping chambers measures maximum when ka is minimum, and the influence of H/d keeps on reducing when the ka approaches the maximum value. The insertion of the curtain wall reduces the free surface oscillation at the pumping chamber when the relative water depth (d/L) ranges from 0.21 to 0.36.

Design of an updraft gasification stove and its performance test with cassava peel as fuel

In this study, an insulated updraft gasification stove for biomass has been designed and tested for cassava peel. The main components of the stove were forced airflow inlet, biomass bed and gasification chamber and ceramic wool-insulated stainless steel wall. Top lit method was used in the ignition and testing was performed by using water boiling test method. Cassava peel was fed at four levels of bulk densities and moisture content. The result showed that combustion rates were quite high. The bulk density of fuel tend to reduce the rate of combustion and ignition front speed. The cassava peel with moisture content of 8-10% showed reddish-purple flame and small amount of smoke produced while with moisture content above 15%, the fuel could not be ignited in a reasonable time. The thermal system efficiencies of this gasification stove were still quite low, which were between 5.88 to 8.79%.

Performance Improvement of Swirl Type Micro Bubble Generator

Micro bubbles measuring tens of micrometers or less in diameter have recently been paid much attention. Swirl type, pressurizing dissolution, and perforated plate methods have been proposed for micro bubble generation. The swirl type method can generate micro bubbles even under low-pressure power in a simple structure. This study examined the effect of the swirl chamber inlet diameter on the bubble diameter in a swirl type micro bubble generator. The swirl chamber inlet diameter was varied in the range of 15-90 mm and the effect was examined. In order to clarify the effect of enlarged inlet diameter, the micro bubbles diameter was measured under changing water supply pressure and air flow rate, the behavior of air column in the swirl chamber was visualized, and the velocity distribution around outlet of swirl chamber was measured. As a result, when the swirl chamber inlet diameter was enlarged, the outflow form changed from an axial outflow to a radial outflow. The average bubble diameter could also be reduced. An average bubble diameter of 28 μm could be realized under the conditions of swirl inlet diameter of 90 mm and water supply pressure of 0.1 MPa gage.