Function Of Air Flow Rate Research Articles

Influence of airflow and ligament tension on the acoustics of a biomimetic larynx model

The phonation process is a complex interaction involving the airflow from the lungs, the oscillation of the vocal folds’ tissue, and the resultant acoustics. To understand the underlying physical mechanisms, an experimental model has been designed that allow the control of flowrate and longitudinal tension of the vocal folds. A synthetic biomimetic larynx model was applied that features airflow-driven vocal folds’ oscillations. The longitudinal stiffness of the vocal folds is controlled using embedded ligament fibers. The model enables to measure aerodynamic and acoustic signals as function of airflow rate and the fiber tension. Based on the measured signals, the influence of airflow and fiber tension was statistically analyzed using the parameters F0, Psub, CPP, HNR, Shimmer, and Jitter. The statistical analysis revealed that both flowrate and fiber tension significantly influence acoustic and aerodynamic parameters. In general, the parameters showed different trends for increasing flowrate and fiber tension. Increase in fiber tension produced increasing parameters up to a maximum tension level followed by a saturation of the parameters. In contrast, the flowrate showed varying trends depending on the respective parameter. The results clearly show how flowrate and longitudinal tension control the phonation process and the resulting acoustic quality.

벤치규모 생물반응기에서 Shinella granuli CK-4에 의한 1,4-Dioxane의 생분해에 영향을 미치는 물리화학적 요인

Our previous research has demonstrated that Shinella granuli CK-4 is capable of utilizing 1,4-dioxane as its sole source of carbon and energy when isolated from industrial wastewater [1]. In this study, we have extended this work to investigate the relationships between 1,4-dioxane degradation and the strain CK-4 and several relevant physicochemical environmental parameters in 3 L bench-scale bioreactors. One gram of 1,4-dioxane per liter was completely degraded within 96 hours of incubation, and the optimum temperature for 1,4-dioxane degradation was 30oC. 1,4-Dioxane degradation by CK-4 gradually increased as a function of airflow rate and agitation speed, and the optimum airflow rate and agitation speed were 2.5 L/min and 500 rotation per minutes, respectively, in this study. The addition of 50 mg/L tetrahydrofuran as a supplemental carbon source was found to stimulate the maximal bacterial growth and 1,4-dioxane degradation. The optimum results obtained from these experiments were combined and applied for 1,4-dioxane degradation. As a result, the complete degradation of 1,4-dioxane was achieved with the CK-4 culture within 72 hours of incubation. We explored the feasibility of using the cultures of S. granuli CK-4 for the degradation of 1,4-dioxane with the aim of microbial application in industrial wastewater treatment in bench-scale bioreactors.

Experimental Analysis and Performance Evaluation of Solid Desiccant Dehumidifier Using Silica Gel

Simple and Economical method to produce dehumidification is by solid desiccant wheel with a desiccant material (silica gel) which attract moisture from moist air. Experimental analysis of the working of the dehumidifier desiccant wheel is indicated in this work with actual thought to the performance deviation as a function of airflow rates at the process side and ambient temperature for hot and humid conditions. The silica gel is reactivated by an electric heater which is fixed in the reactivation portion. Flow rates of the air have been varied (that is, 2.8, 3.5, 4.5, & 5.2 m/s) at the process section of the desiccant wheel, while on the reactivation section, airflow rate is constant (i.e., 2.8m/s). At various ambient temperatures (i.e., 32, 33, 34, & 35°C) and various airflow rates, performance parameters also analyzed like Moisture Removal Capacity (MRC), Dehumidification Coefficient of Performance (DCOP), dehumidification effectiveness, and Sensible Energy Ratio (SER). We observed that the optimum values of these performance parameters in this work are obtained at 3.5m/s air velocity at the process section and 34℃ ambient temperature. Optimum values of these parameters show a decrease in energy used and improved air quality in the conditioned space.

Experimental Investigation on Improvement of Wet Cooling Tower Efficiency with Diverse Packing Compaction Using ANN-PSO Algorithm

In this study, a numerical and empirical scheme for increasing cooling tower performance is developed by combining the particle swarm optimization (PSO) algorithm with a neural network and considering the packing’s compaction as an effective factor for higher accuracies. An experimental setup is used to analyze the effects of packing compaction on the performance. The neural network is optimized by the PSO algorithm in order to predict the precise temperature difference, efficiency, and outlet temperature, which are functions of air flow rate, water flow rate, inlet water temperature, inlet air temperature, inlet air relative humidity, and packing compaction. The effects of water flow rate, air flow rate, inlet water temperature, and packing compaction on the performance are examined. A new empirical model for the cooling tower performance and efficiency is also developed. Finally, the optimized performance conditions of the cooling tower are obtained by the presented correlations. The results reveal that cooling tower efficiency is increased by increasing the air flow rate, water flow rate, and packing compaction.

Solar Powered Air Conditioning System Using Rotary Honeycomb Desiccant Wheel.(Dept.M)

A solar powered air conditioning system using a liquid desiccant is proposed to overcome the latent heat part of the cooling load in the air conditioning system. A solar air heater containing a porous material is used as a heat absorber. In addition, a rotating wheel containing a honeycomb clothes saturated with Calcium Chloride solution, is utilized for the regeneration and absorption processes. Different system parameters are investigated. The effect of airflow rate and solar radiation intensity on the system regeneration and absorption abilities are studied. The obtained results show that the system is highly effective in the regeneration process. Also, the system is feasible and energy-efficient in comparison with the traditional electric dehumidification. Furthermore, the system can be used to extract a reasonable amount of water from air. An empirical equation to calculate the removed moisture as a function of air flow rate at solar noon is obtained.

Performance analysis of liquified petroleum gas (LPG) driven half-cycle air conditioning system

Liquified petroleum gas (LPG) is one of the potential refrigerants to be used in half-cycle air conditioning systems. After evaporation to get air-conditioning, LPG may be further used in combustion applications such as electric-generators, auto-motives and cooking stoves. Expansion device (or a flow control valve) is usually used before the evaporator to make sure that the refrigerant vaporizes in evaporator and provides cooling. The present study reports the investigation of an experimental study to determine the performance of three in-house designed and manufactured evaporators for an air conditioning system using LPG as refrigerant. The evaporators used are finned-tube evaporators having difference in tube arrangements, fin materials, fin spacing and tube dimensions. The thermal energy to evaporate LPG is obtained from air driven by a fan attached to one side of the evaporator. Cold air exiting from the evaporator is then supplied to a cabin having the similar dimensions of an automotive rickshaw. The performance parameters determined for a fixed time duration for different fan speeds include; the cooling effect, contact factor and rate of condensation. The investigations were conducted for different LPG flow rates and evaporative pressures. The test results show that for each flow condition; the cooling effect, contact factor and rate of condensation are also the function of air flow rate passing through the evaporator. Experimentally determined cooling effects were then analytically validated by using the Nusselt number correlations of Grimison model, modified Grimison model and Zhukauskas model for each of the evaporators used.

Evaluation of Stochastic and Periodic Cellular Materials for Combined Heat Dissipation and Noise Reduction: Experiments and Modeling

In many high-performance compact air-cooling technologies, it is desirable to adopt materials that provide combined heat dissipation with noise reduction (NR) in the same device. A device that adopts such material is termed here as a “noise-reducing heat sink” (NRHS). NRHS design would involve fundamental thermal-acoustic performance tradeoffs, thus necessitating investigation of their combined thermal-acoustic performance. In this article, the thermal-acoustic performance of NRHS is evaluated by determining their thermal-acoustic index (TAI) as a function of airflow rates (Mach number < 0.1). This index is determined by combining thermal resistance as the basis for thermal performance characterization and NR improvement to characterize the acoustic performance. Conventional parallel-plate heat sinks/slit-based geometries, stochastic metal foams, and a designed periodic foam structure are compared as NRHS candidates. The results show that, for the same material volume fraction, stochastic metal foam heat sinks have better combined thermal-acoustic performance compared with a conventional parallel-plate heat sink. A designed periodic foam NRHS is shown to have significantly improved TAI, thus leading the way for NRHS design in compact cooling technologies. For the best combined thermal and acoustic performance, laminar flow is identified as a suitable operational flow regime.

Tumor localization accuracy for high-precision radiotherapy during active breath-hold

BackgroundConventionally fractionated and stereotactic body radiation therapy (SBRT) for thoracoabdominal tumors may utilize breath-hold techniques. However, there are concerns that differential amounts of inspired airflow may result in unplanned tumor dislocation and underdosing. Thus, we investigated tumor localization accuracy associated with lung volume variations during breath-hold treatment via an automated-gating interface. MethodsTwelve patients received breath-hold treatment with the active breathing coordinator (ABC) through an automated-gating interface. All breath-hold volumes were recorded at CT simulation, setup imaging, and during treatment, and analyzed as a function of airflow rate into the ABC. The variation of breath-hold volumes was calculated for each fraction over entire course. Intrafraction target motion related to the breathing variation was investigated based on daily imaging acquired before the breath-hold treatment. Correlation between target location and breath-hold variation was statistically analyzed. ResultsThe air volume held by the ABC increased as the airflow rate increased on inhalation and decreased on exhalation. The mean range of airflow rate was 0.77 L/s and 0.29 L/s in the conventionally fractionated and SBRT patients, respectively. The maximum air volume difference with respect to the reference volume at the CT simulation was 1.0 L for conventional fractionation and 0.16 L for SBRT. The target dislocation caused by 0.25 L of air volume difference was 6 mm for SBRT. Three patients showed significant correlation between the target location and breath-hold variations. ConclusionsThis investigation shows that because variations in the breath-hold volume may cause target dislocation, patient-specific breath-hold setting is required to improve tumor localization accuracy.

Hydrodynamics of Packed Bed Column: Study of the Column for the Absorption of CO2 in Water and its Efficiency

Hydrodynamics and rate of absorption of gas into liquid contribute much in the overall efficiency of the absorption column which are widely used in the food industry, oil refineries, power plants and in the coal fired stations to control the pollution of air. It is noted that the range of possible air flow rates decreases as long as water flow rate goes to increase unless onset of the flooding of the column happen. Absorption of the carbon dioxide through solvent was carried out on the laboratory scale absorption column. By the motion of water, the dynamics of column was noted. Pressure differential was measured at the three tapings provided at three points of the column. Actually pressure differential was measured as a function of air flow rate for each water flow rate measured.

Identification model and PI and PID controller design for a novel electric air heater

ABSTRACTIn this article, the software and hardware control architecture for a novel high-temperature three-phase electric air heating furnace is presented. It consists of a multiple-input single-output (MISO) nonlinear plant designed to heat air at flow rates in a range between 10 and 60 Nm3/h, from ambient temperature up to 1000 °C.A divide-and-conquer (D&C) approach is applied. It consists in discretizing the air flow rates and working temperatures in intervals where the system behaviour is considered as single-input single-output (SISO) linear plant. Process identification techniques have been used to obtain empiric models for different operation ranges of the electric furnace. The controller parameters have been calculated using the Ziegler–Nichols tuning method.The resulting output air temperature control is composed of a set of 12 PI and PID controllers. The switch among controllers as a function of air flow rates and temperatures is carried out using programming logic and gain scheduling technique, respectively. The resulting multiple controller has been tested under real conditions and the results are presented and discussed.

Analysis of protein enrichment during single- and multi-stage tribo-electrostatic bioseparation processes for dry fractionation of legume flour

Abstract The potential of a dry fractionation approach for the production of native plant protein concentrates has been validated for navy bean ( Phaseolus vulgaris ) flour as a model system utilizing a lab-scale tribo-electrostatic separator. For this approach, protein and carbohydrate particles in pin-milled flour were tribo-charged to different levels before being fractionated according to their acquired charge under the influence of an applied electric field. In the present study, the location and distribution of the charged protein-rich particles along the surface of the electrode plate was investigated as a function of air flow rate (laminar vs . turbulent) and electric field strength. A turbulent air flow rate at a variety of electric field strengths resulted in the formation of protein-rich particles and starch granule agglomerates affecting the production of high-purity protein concentrates. Charging the flour particles at a laminar air flow rate followed by separation under a low electric field strength enabled the production of fine protein-rich fractions with considerably higher protein contents (38.4–46.5%) but lower protein separation efficiency. The combination of a laminar air flow rate and high electrode voltage slightly reduced the protein content of the fraction (39.4–42.9%), but significantly improved the protein separation efficiency to ∼45%. To further improve the separation efficiency of the navy bean protein concentrate without compromising its protein content, a two-stage tribo-electrostatic separation approach was evaluated at a laminar air flow but different plate voltages. The combined protein-rich fraction produced by the two-stage approach had a protein content of ∼38% accounting for 60% of the total protein that was significantly higher than that of the optimized single-stage tribo-electrostatic separation, facilitating the scale-up of this dry fractionation technique for pilot-plant applications.

Degradation Study of Yttria Doped Barium Cerate (BCY) Electrolyte in Protonic Ceramic Fuel Cells Under Various Test Conditions

Acceptor-doped barium cerate has been considered as a potential electrolyte material in solid oxide fuel cell because of its high proton conductivity at temperatures below 7000C. However, despite its superior transport property, barium cerate cannot be practically used in fuel cell due to its poor chemical stability in the atmosphere of water vapor and carbon dioxide. In the present work, we fabricated two kinds of BCY based anode supported cells, 1) BCY single layer cell and 2) BCY/BZY bi-layer cell, and their stability and degradation mechanism were investigated and compared, especially under severe operating conditions such as a negative voltage and low air flow rate. Constant current (CC) tests were conducted on the cells under various operating conditions such as positive vs. negative cell voltage and high vs. low fuel/air flow rate. Constant current (CC) tests were conducted on the BCY single layer and BCY/BZY bi-layer cells under a negative well as well a positive cell voltage as a function of air flow rate. Before and after the CC tests, I-V curve and impedance spectra were measured and compared to trace any increase in ohmic and/or non-ohmic resistance of the cells. Post-material analyses were conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) to find out any change in microstructure and phase after severe operations.

Effect of submergence ratio on the liquid phase velocity, efficiency and void fraction in an air-lift pump

Abstract The effects of submergence ratio and gas flow rate on the induced liquid flow rate, efficiency and void fraction have been investigated in an air-lift system. The experiments were conducted using a transparent riser pipe of 3.1 m length and 33 mm inner diameter. The evolution of liquid flow rate in function of air flow rate presents a first step of rapid growth followed by a constant liquid flow rate depending on the submergence ratio. These operating regimes have been linked to slug flow and churn flow correspondingly. It has been observed that the highest performance of the air-lift pump is related to the slug flow and slug to churn flow transition. The results also show that the minimum of superficial velocity ratio of the phases coincides with the maximum of pump efficiency. The maximum pump efficiency decreases for submergence ratios beyond 0.75. The behavior of void fraction, when the liquid is in circulation, is characterized by mean regular growth with an air flow rate accompanied by variations inherent to the dynamics of two-phase flow and is well represented using the drift-flux model. The results also show that the evolution of void fraction with slip ratio for air-lift system is different when compared to others two phase upward flows.

An investigation into the deposition of inhalation aerosol particles as a function of air flow rate in a modified 'Kirk Lung'.

The effect of air flow rate on the deposition of inhalation aerosol particles in a modified 'Kirk Lung' has been studied. Two commercial products were used. The amount depositied in the mouthpiece and throat regions decreases with increasing flow rate. The amount in the collector rises to maximum of approximately 50%. This material represents the therapeutically available portion. Such an apparatus would be useful for routine quality control of the size distribution ratios for inhalation aerosol particles.

ボルテックスバースティングによる細管内の火炎伝播に関する実験的研究(熱工学,内燃機関,動力など)

Flame propagation in a small diameter tube has been experimentally investigated. Methane/air and propane/air mixtures were injected into the small diameter tube from a swirl generator installed at one end of the tube, ignited at the other open end, and the propagation limits have been determined as function of air flow rate and the mixture equivalence ratio. Results show that, when the tube inner diameter is greater than 3.6mm, flame through the vortex bursting mechanism become possible. An increase in the air flow rate leads to an increase of the propagation range in equivalence ratio, whereas a decrease in the air flow rate leads to a decrease of the propagation range, and eventually a flame cannot propagate upstream for any equivalence ratio of the mixture. Further experiments have showed that, as the swirl intensity is increased, flame propagation range becomes widened in the mapping of the equivalence ratio and the air flow rate. The range of equivalence ratio Φ for which the flame propagation due to vortex bursting becomes possible is on relatively fuel lean side between 0.75 and 1.1 for methane/air mixtures, whereas the range is quite limited on very fuel rich side between 1.1 and 2.2 for propane/air mixture. These ranges are much narrower than those for the vortex induced flame propagation in an open air or in a very large diameter tube, suggesting strong influence of the Lewis number of a deficient species for the occurrence of vortex induced flame propagation in a small diameter tube.

Fungal spore fragmentation as a function of airflow rates and fungal generation methods

The aim of this study was to characterise and quantify the fungal fragment propagules derived and released from several fungal species ( Penicillium, Aspergillus niger and Cladosporium cladosporioides) using different generation methods and different air velocities over the colonies. Real time fungal spore fragmentation was investigated using an Ultraviolet Aerodynamic Particle Sizer (UVASP) and a Scanning Mobility Particle Sizer (SMPS). The study showed that there were significant differences ( p < 0.01) in the fragmentation percentage between different air velocities for the three generation methods, namely the direct, the fan and the fungal spore source strength tester (FSSST) methods. The percentage of fragmentation also proved to be dependent on fungal species. The study found that there was no fragmentation for any of the fungal species at an air velocity ≤0.4 m s −1 for any method of generation. Fluorescent signals, as well as mathematical determination also showed that the fungal fragments were derived from spores. Correlation analysis showed that the number of released fragments measured by the UVAPS under controlled conditions can be predicted on the basis of the number of spores, for Penicillium and A. niger, but not for C. cladosporioides. The fluorescence percentage of fragment samples was found to be significantly different to that of non-fragment samples ( p < 0.0001) and the fragment sample fluorescence was always less than that of the non-fragment samples. Size distribution and concentration of fungal fragment particles were investigated qualitatively and quantitatively, by both UVAPS and SMPS, and it was found that the UVAPS was more sensitive than the SMPS for measuring small sample concentrations, whilethe results obtained from the UVAPS and SMAS were not identical for the same samples.

The relationship between the peak in air recovery and flotation bank performance

Air recovery, or the fraction of air entering a cell that overflows the cell lip as unburst bubbles, is an important measure of froth stability as it affects the flow of bubble surface to the concentrate. An experimental campaign was carried out over the first four cells of the rougher bank at a South African platinum mine in order to find the relationship between froth stability and flotation performance as a function of air flowrate. The results showed that a peak in air recovery was observed as the air rate increased. Furthermore, this corresponded to the air flowrate at which the highest overall recovery was obtained. This can be explained by understanding the resulting changes in the structural features of the froth such as bubble loading and the flow of bubble surface and suggests that improved flotation performance can be achieved by operating a bank under conditions that result in a maximum in froth stability.

A study of ionization and collection efficiencies in electrospray-based electrostatic precipitators

Ozone-free electrostatic precipitators incorporating an array of electrospray wick charged aerosol ionization sources were built and tested. The particle ionization and collection efficiencies were independently measured for airborne particles as a function of air flow rate, electric field magnitude, and particle size. The results indicate that, while particle ionization efficiencies near 100% can be achieved using the electrospray ionization method, the number of elemental charges deposited onto a given particle depends strongly on the particle diameter and for submicron particles is very low. High overall particle collection efficiency, therefore, requires a carefully designed precipitation region where the maximum particle collection time, associated with the particles with the lowest mobility, is less than the residence time within the collector.

The Effect of Air Flow on Measured Heat Transport through Wall Cavity Insulation

Abstract The methods commonly used for determining the thermal resistance of insulations in wall cavities do not include the effect of air movement through the insulation. Contributions to the total building heating or cooling load include the change in enthalpy of air moving through an insulation and the heat flux through the insulation due to the imposed thermal gradient. The two effects are not independent since the air movement affects the temperature distribution in the insulation. A heat-flow-meter apparatus meeting the requirements of the Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus ASTM C 518 has been configured to allow uniform air flow across thermal test specimens. The air flow is parallel to the heat flow direction. Air is introduced into the specimen chamber of the heat-flow-meter apparatus from an external source. The heat-flow-meter with controlled air flow has been used to determine total heat-flow rates as a function of air-flow rate, air-flow direction, and temperature for commonly used wall cavity insulation.

Solar powered air conditioning system using rotary honeycomb desiccant wheel

A solar powered air conditioning system using liquid desiccant is proposed. A solar air heater containing a porous material is used for regeneration purpose in the proposed system. The honeycomb desiccant rotary wheel is constructed from iron wire and clothes layer impregnated with calcium chloride solution, in honeycomb form, is utilized for the regeneration and absorption processes. The effect of airflow rate and solar radiation intensity on the system regeneration and absorption processes are studied. The obtained results show that the system is highly effective in the regeneration process. An empirical equation to calculate the removed moisture as a function of air flow rate at solar noon is obtained. Also empirical equation for wheel effectiveness as a function of air flow rate for regeneration and absorption process was obtained.