Pressurized Air Flow Research Articles

Vayu bubble continuous positive airway pressure is a promising solution with favorable treatment outcomes for respiratory distress syndrome in newborns: a qualitative study in Bangladesh.

According to Bangladesh Demographic and Health Survey (2022), neonatal mortality, comprising 67% of under-5 deaths in Bangladesh, is significantly attributed to prematurity and low birth weight (LBW), accounting for 32% of neonatal deaths. Respiratory distress syndrome (RDS) is a prevalent concern among preterm and LBW infants, leading to substantial mortality. The World Health Organization (WHO) recommends bubble continuous positive airway pressure (bCPAP) therapy, but the affordability and accessibility of conventional bCPAP devices for a large number of patients become major hurdles in Bangladesh due to high costs and resource intensiveness. The Vayu bCPAP, a simple and portable alternative, offers a constant flow of oxygen-enriched, filtered, humidified, and pressurized air. Our study, conducted in five health facilities, explores the useability, acceptability, and perceived treatment outcome of Vayu bCPAP in the local context of Bangladesh. A qualitative approach was employed in special care newborn units (SCANUs) of selected facilities from January to March 2023. Purposive sampling identified nine key informants, 40 in-depth interviews with service providers, and 10 focus group discussions. Data collection and analysis utilized a thematic framework approach led by trained anthropologists and medical officers. Service providers acknowledged Vayu bCPAP as a lightweight, easily movable, and cost-effective device requiring minimal training. Despite challenges such as consumable shortages and maintenance issues, providers perceived the device as user-friendly, operable with oxygen cylinders, and beneficial during referral transportation. Treatment outcomes indicated effective RDS management, reduced hospital stays, and decreased referrals. Though challenges existed, healthcare providers and facility managers expressed enthusiasm for Vayu bCPAP due to its potential to simplify advanced neonatal care delivery. The Vayu bCPAP device demonstrated useability, acceptability, and favorable treatment outcomes in the care of neonates with RDS. However, sustained quality service necessitates continuous monitoring, mentoring and retention of knowledge and skills. Despite challenges, the enthusiasm among healthcare providers underscores the potential of Vayu bCPAP to save lives and simplify neonatal care delivery. Development of Standard Operating procedure on Vayu bCPAP is required for systematic implementation. Further research is needed to determine how the utilization of Vayu bCPAP devices enhances accessibility to efficient bCPAP therapy for neonates experiencing RDS.

RETRACTED: Experimental investigation on sustainable cycling of thermochemical energy storage Ca(OH)2/CaO using a pressurized air flow

The Ca(OH)2 to CaO and water vapor reaction can be reversed and used for thermochemical energy storage, making it a highly promising method for utilizing solar thermal energy and recycling industrial waste heat. In this study, an experimental platform using a pressurized air flow was established to investigate the cyclic performance of the thermochemical energy storage Ca(OH)2/CaO. Then a series of dehydration/hydration experiments which can be used for practical engineering was carried out, and it was found that the dehydration at a temperature exceeding 650 °C can effectively restore the cyclic performance. Subsequently, more than successive 20 cycles at below 650 °C were conducted, and the results show a decrease of 5.9 % in the conversion of the energy storage reaction after 10 cycles, followed by a continuous decrease of 3.6 % in the next 10 cycles. The thermogravimetry (TG) and particle size tests demonstrate that CO2 is the primary factor causing cyclic performance degradation, while an excess temperature of 650 °C can effectively reduce the CaCO3 content in the reactants. This study establishes a basis for the effective implementation of thermochemical energy storage Ca(OH)2/CaO in engineering applications.

Indoor Floor Heel Mark Removal Using Spark Discharges and Pressurized Airflow

Heel marks (HMs), which are the black stains made by shoe soles on indoor floors, can be difficult to remove. However, this study shows how spark discharges combined with pressurized airflow in 60 s discharge treatments can remove such HMs. We further show that maximizing the HM removal rates depended on the electrode gap distance because of changes in the spark discharge parameters. In our experiments, the electrical voltage waveforms are shown with voltage spikes, called spark discharges, and the spike numbers were counted in 0.6-ms time units. It was found that the number of spark discharges increases when the electrode gap distance was widened from 5 mm to 10 mm and the pressurized airflow was added, and the HM removal rates increased 11.5%, the HM removal rates could be maximized. Taken together, the results show that spark discharges combined with pressurized air can remove HMs from indoor floors without no visual damage. This paper is a preliminary report showing that HMs can be removed by plasma.

OsciCheck: A Novel Fluidic Transducer for Air-Coupled Ultrasonic Measurements

Ultrasonic measurement technology has become indispensable in NDT-CE. Air-coupled ultrasonic (ACU) measurement techniques promise to reduce measurement time. However, the signal quality suffers from large specific impedance mismatch at the transducer-air and air-specimen interface. Additionally, large pressure amplitudes are necessary for the penetration depth required in NDT-CE applications. To address the specific requirements of ultrasonic testing in NDT-CE, a robust ACU transducer was developed, that generates ultrasound by quickly switching a pressurized air flow. The simple design of the fluidic transducer makes the device maintenance free and resilient against harsh environmental conditions. Since the signal is generated by aeroacoustics, there is no specific impedance mismatch between the transducer and the surrounding air. The ultrasonic signal exhibits frequencies in the 30-60 kHz range and is therefore well suited to penetrate heterogenous materials such as concrete. This contribution gives an introduction in the working principle and signal characteristics of the fluidic transducer. Its application on different materials is validated. A detailed outlook is given to discuss the future potential of fluidic ultrasonic actuators.

An Experimental Study on the Force Coefficient and the Discharge Coefficient of a Safety Valve in Air-water Mixture Flow

Due to the low number of experimental investigations on the sizing of safety valves in multiphase flow, a novel set of measurement data of an air-water mixture is reported. This paper presents an experimental study on three different geometries of safety valves, a poppet valve with jet angle θ = 120°, and two-disc valves with deflection angles θ = 0° and θ = 90°, respectively. Our test rig comprises a pipeline with 42.5 mm inner diameter, spray nozzles to supply the added water quality (water mass fraction) to the pressurized airflow up to 40 % mass fraction and an inlet pressure up to 6.6 bar(g). The time histories of force, valve lift, and pressures were recorded. We present correlation data for the force coefficient and the discharge coefficient. The widely used omega technique for the Homogenous Equilibrium Model (HEM) is employed to predict the theoretical mass flux. The results show that the poppet valve experiences less momentum force and lower mass flow rates compared to disc valves, while the disc valve with deflection angle θ = 90° presents the highest discharged flow rates among the tested geometries. Our most important finding is that up to 60 % relative valve lift and 40 % mass fraction, neither the force nor the discharge coefficient changes significantly compared to the pure-air case. Finally, we propose a new correlation with a single equation for the resultant force and the discharge coefficient as a function of the relative valve lift for all tested water mass fractions.

Physicochemical analysis, microbial survivability, and shelf life study of spray‐dried synbiotic guava juice powder

In this work the survival of Lactobacillus plantarum in guava juice upon spray-drying process using maltodextrin (MD) and inulin (INU) as drying carriers was evaluated. The microbial viability, color, water activity (Aw), and rehydration time in spray-dried lacto-fermented guava juice powder were evaluated at room temperature (25°C) and refrigerated conditions (4°C) for 45 days. Spray drying was done at inlet temperature of drying air 120°C, feed flow rate 5 ml/min, hot air flow 3.0 m3/min, pressurized air flow 30 L/min, and outlet temperature at 75°C. Results indicated that the highest survival rates of 80% for 45 days and 85% up to 15 days were observed at 4°C and 25°C, respectively, for powders obtained using 10% MD + 10% INU blend. Highest yield and lowest rehydration time were obtained by 20% MD. Aw was maintained low and no color difference in the product was seen in any of the formulations. Practical Applications The practical applications of this research will help in catering the growing demand for functional foods with nondairy food matrix containing both prebiotics and probiotics (known as synbiotic). In the present work a source of prebiotic-guava and lactobacillus strain as a probiotic was used to formulate a, synbiotic beverage which was then spray dried in optimized method. Such unique combinations improve the nutritional attributes and bring forth health benefits of fruit juices, and delivers health potential from both sources (fruit juices and probiotics). This spray-dried synbiotic powder will be a preferred choice for lactose-intolerant people. The synbiotic not only help in immunomodulatory functions but also help in efficient functioning of gut microbiota which is scientifically related to many body vitals. The most critical practical challenge of preserving the needed microbial viability over shelf life is also dealt with in the present work. This consumer friendly form not only offers an ease of commercial transport but a closely packed form of deliverables for combating micronutrient deficiency.

Therapeutic Aerosol: Thermodynamic Method for Managing the Aerosol Particle Size

The inhalation therapy delivers the drugs to the sites and helps to release a respiratory route. The aerosol therapy results highly depend on the depth of drug penetration into the respiratory system, which is primarily determined by the optimal size of the aerosol particles, the farther their penetration is required, the smaller their size should be. In clinical practice, various modes are used to generate the desired particle size. As a result, the drug particles in a certain size are obtained for a more accurate delivery system. However, such different methods for changing the size of drug particles do not provide satisfactory results. Also, the applied pressure in the aerosol technique allows traveling the drug particles at a rapid-uncontrolled speed, causing impaction in the respiratory route. The aerosol is unstable and changes its state under different circumstances, such as the influence of gravity, coagulation, and others. Conventional aerosol nebulizer does not have the privileges, similar to that in the aerosols that used dry powder inhaler or colloidal solutions, which would interfere with the adhesion of particles. In this paper, the authors developed a mathematical approach based on using hot pressurized airflow to control particle size, also determine the speed and the entire time of droplet (drug particles) evaporation. As a result, it can be managed the decreasing of the larger particle sizes and guarantee more deposition of drugs. The proposed method prevents particles from adhering to each other and delivering the best percentage of the drug to the lungs.

Analisa Volume Air Hasil Pemampatan Udara Kompresor Torak Puma Pk-50-160a Terhadap Waktu Loading

The capacity of the air volume in the compressor is reduced due to the presence of water in the compressor tube. Narrowing of the compressor cylinder caused by compressed air can shorten the compressor loading time which results in a reduction in the amount of pressurized air flow required in the pneumatic system. With the knowledge of the volume of water resulting from compressed air, it can easily determine the schedule of disposal of water that is in the compressor tube, so as to maximize the performance of the compressor. This research is a type of quantitative research because it involves calculation of numbers or quantification of data. The technique of collecting data is done by observation. From this research, the volume of water contained in the compressor tube which affects loading time is 27 liters which can shorten the loading time by 0.5 minutes and because water is an incompressible fluid, the compressor tube which was originally 160 liters capacity is reduced to 133 liters. What can be obtained from this research is that the reduced compressor capacity can have an impact on the amount of pressurized air flow in the pneumatic system.

Qualitative Assessment of the Effect of Continuous Positive Airway Pressure on the Nasal Cavity.

For patients with obstructive sleep apnea (OSA), there is a lack of knowledge regarding the impact of continuous positive airway pressure (CPAP) on the nasal cavity. There is a significant need for evidence-based recommendations regarding the appropriate use of CPAP following endoscopic sinus and skull base surgery. The goal of this study is to translate a previously developed cadaveric model for evaluating CPAP pressures in the sinonasal cavity by showing safety in vivo and quantifying the effect of positive pressurized air flow on the nasal cavity of healthy individuals where physiologic effects are at play. A previously validated cadaveric model using intracranial sensor catheters has proved to be a reliable technique for measuring sinonasal pressures. These sensors were placed in the nasal cavity of 18 healthy individuals. Pressure within the nose was recorded at increasing levels of CPAP. Overall, nasal cavity pressure was on average 85% of delivered CPAP. The amount of pressure delivered to the nasal cavity increased as the CPAP increased. The percentage of CPAP delivered was 77% for 5 cmH2O and increased to 89% at 20 cmH2O. There was a significant difference in mean intranasal pressures between all the levels of CPAP except 5 cmH2O and 8 cmH2O (P < .001). On average, only 85% of the pressure delivered by CPAP is transmitted to the nasal cavity. Higher CPAP pressures delivered a greater percentage of pressurized air to the nasal cavity floor. Our results are comparable to the cadaver model, which demonstrated similar pressure delivery even in the absence of anatomic factors such as lung compliance, nasal secretions, and edema. This study demonstrates the safety of using sensors in the human nasal cavity. This technology can also be utilized to evaluate the resiliency of various repair techniques for endoscopic skull base surgery with CPAP administration.

Optimization of dust removal performance of ventilation system in tunnel constructed using shield tunneling machine

Dust that is produced when a tunnel is being constructed using a shield tunneling machine is an important factor that affects the operating environment. A ventilation dust removal system is an effective tool for suppressing the diffusion of such dust particles. In this study, the operating process of the ventilation dust removal system of a shield tunneling machine was analyzed. Subsequently, through an orthogonal test, the effects of pressurized air flow rate, air extraction flow rate, and diameter of pressurized air duct on dust control distance are investigated in depth. Specifically, Factor A (pressurized air flow rate) imposed the most significant effect on the dust control distance, followed by Factor B (air extraction flow rate), and finally by Factor C (diameter of pressurized air duct). The optimal combination was determined as A1B4C3. On applying this optimal combination, the dust control distance of the ventilation dust removal system was 23.54 m, which was 30.11 m shorter than that of the original ventilation system. Therefore, using this optimal ventilation system, the dust that is produced can be controlled around the main engine, and the dust control performance can be improved considerably.

Shortening Stabilization Time Using Pressurized Air Flow in Manufacturing Mesophase Pitch-Based Carbon Fiber.

Oxidation–stabilization using pressurized air flows of 0.5 and 1.0 MPa could successfully shorten the total stabilization time to less than 60 min for manufacturing mesophase pitch-based carbon fibers without deteriorating mechanical performance. Notably, the carbonized fiber heat-treated at 1000 °C for 30 min, which was oxidative–stabilized at 260 °C without soaking time with a heating rate of 2.0 °C/min using 100 mL/min of pressurized air flow of 0.5 MPa (total stabilization time: 55 min), showed excellent tensile strength and Young′s modulus of 3.4 and 177 GPa, respectively, which were higher than those of carbonized fiber oxidation–stabilized at 270 °C without soaking time with a heating rate of 0.5 °C/min using 100 mL/min of atmospheric air flow (total stabilization time: 300 min). Activation energies for oxidation reactions in stabilization using pressurized air flows were much lower than those of oxidation reactions using atmospheric air flow because of the higher oxidation diffusion from the outer surface into the center part of pitch fibers for the use of the pressurized air flows of 0.5 and 1.0 MPa than the atmospheric one. The higher oxygen diffusivities resulted in a more homogeneous distribution of oxygen weight uptake across the transverse section of mesophase pitch fibers, and allowed the improvement of the mechanical properties.

Highly efficient electro-generation of H2O2 by adjusting liquid-gas-solid three phase interfaces of porous carbonaceous cathode during oxygen reduction reaction

Equilibrium of three reactants (oxygen, proton and electron) in oxygen reduction reaction at large current flux is necessary for highly efficient electro-generation of H2O2. In this work, we investigated reactants equilibrium and H2O2 electrochemical production in liquid-gas-solid three phase interfaces on rolling cathodes with high electroactive area. Electrocatalytic reaction accelerated the electrolyte intrusion into hydrophobic porous catalyst layer for higher electroactive surface area, resulting in a 21% increase of H2O2 yield at 15 mA cm−2. Air aerated cathode submerged in air/O2 aeration solution was unable to produce H2O2 efficiently due to the lack of O2 in three phase interfaces (TPIs), especially at current density > 2.5 mA cm−2. For air breathing cathode, stable TPIs inside the active sites was created by addition of gas diffusion layer, to increase H2O2 production from 11 ± 2 to 172 ± 11 mg L−1 h−1 at 15 mA cm−2. Pressurized air flow application enhanced both oxygen supply and H2O2 departure transfer to obtain a high H2O2 production of 461 ± 11 mg L−1 h−1 with CE of 89 ± 2% at 35 mA cm−2, 45% higher than passive gas transfer systems. Our findings provided a new insight of carbonaceous air cathode performance in producing H2O2, providing important information for the practical application and amplification of cathodes in the future.

Channel orientation effect on endwall heat transfer in rotating cooling passages with pin-fins

Heat transfer was experimentally measured using a rotating pin-fin channel involving two channel orientations, namely 90° and 150°, with respect to a rotating axis. A rectangular channel with an aspect ratio of 4:1 was selected to study internal cooling near the trailing edge of a turbine blade. A newly developed method of liquid crystal thermography along with stroboscopic photography was used to obtain detailed heat transfer contours on an endwall surface. The pin-fin arrays were designed in either inline or staggered patterns, and the Reynolds number ranged from 5,000 to 20,000. The pressurized air flow acted as the working fluid, and the highest rotation number was thus 0.39. The influence of rotation was greater on the inline array than on the staggered array, engendering higher heat transfer enhancement on the leading and trailing surfaces. Compared with the other orientation, the inclined orientation (150°) engendered a larger spanwise heat transfer variation because of the shifted rotation-induced secondary flows. The inline array exhibited the highest rotation-induced heat transfer enhancement at the 90° orientation, and the highest enhancement levels were 90% and 40% on the trailing and leading surfaces, respectively.

Solar electricity via an Air Brayton cycle with an integrated two-step thermochemical cycle for heat storage based on Fe2O3/Fe3O4 redox reactions: Thermodynamic and kinetic analyses

Solar electricity production via an Air Brayton cycle is considered with integrated thermochemical energy storage. The storage is realized via a two-step solar thermochemical cycle based on Fe2O3/Fe3O4 reduction-oxidation reactions, encompassing (1) the thermal reduction of Fe2O3 to Fe3O4 and O2 driven by concentrated solar irradiation under vacuum; and (2) the exothermic oxidation of Fe3O4 with a compressed air stream back to Fe2O3. The steps may be decoupled, resulting in a high temperature, pressurized airflow that is expanded across a turbine to produce on-demand electricity. A thermodynamic analysis of the system determined a maximum cycle efficiency of 46.0% at a solar concentration ratio of 4000 suns, an oxidation pressure of 30 bar, and an approximately 5:1 molar flow rate ratio of air to solid Fe2O3 exiting the re-oxidizer. Chemical kinetics for the thermal reduction of Fe2O3 were determined between approximately 1400 and 1700 K using non-isothermal thermogravimetry with heating rates between 10 and 20 K·s−1 and O2 partial pressures between 0 and 0.05 bar. The rate-limiting reaction mechanism was determined to be nucleation, and kinetic parameters were resolved using an Avrami-Erofe’ev nucleation model with a reaction order of 1.264 ± 0.010. The rate constant followed an Arrhenius-type temperature dependency with an apparent activation energy of 487.0 ± 3.6 kJ·mol−1 and pre-exponential factor 2.768 ± 0.783·1014 s−1. A power-law dependence on O2 partial pressure of order 8.317 ± 0.233 was determined. Non-isothermal thermogravimetry to examine the oxidation of Fe3O4 to Fe2O3 revealed multiple kinetic regimes, and isothermal thermogravimetry showed the reaction proceeded rapidly, within 20 s, at temperatures greater than 673 K. Solid characterization was carried out using scanning electron microscopy and x-ray powder diffractometry up to temperatures of 1073 K to verify initial and final sample compositions and structures.

Experimental characterization on eco-friendly micro-grinding process of titanium alloy using air flow assisted electrospray lubrication with nanofluid

In this paper, a new eco-friendly lubrication technique, which is referred to as the nanofluid air flow assisted electrostatic lubrication (AF-ESL), has been proposed and applied to the micro-grinding process of titanium alloy. In the nanofluid AF-ESL technique, nanofluid droplets can be injected into the grinding region by being driven by an electro-hydro-dynamic force and pressurized air flow. For the experimental performance evaluation, a series of micro-grinding experiments are designed and conducted by varying a size and a weight concentration of nanodiamond particles in the nanofluid. It is demonstrated that the nanofluid AF-ESL can significantly reduce the resultant grinding forces and grinding force ratios. It is also shown that the nanofluid AF-ESL improves the surface quality of ground workpiece and grinding tool condition significantly. In particular, larger nanodiamond particles (80 nm) are more advantageous for enhancing the nanofluid AF-ESL micro-grinding performances. In addition, a weight concentration of nanodiamond particles in the nanofluid is another important factor to influence on the micro-grinding performances.

Influence of perforated draft tube air intake on a pellet coating process

ObjectiveThe main objective of the study was to evaluate the influence of a novel modification of the Wurster draft tube on the particle coating performance. Modification embodies enabling of the additional radial flow of pressurized air through the perforations in the draft tube inner wall. Materials and methodsAfter coating the neutral pellets with polymeric solution, comprising colouring agent, pellet batches were characterized for coating variation, yield and degree of agglomeration. By employing the piezoelectric probe flow regime zones and particle number density profiles inside the draft tube were evaluated, utilizing the power spectral density and particle impact frequency analysis of captured signals, respectively. ResultsThe results clearly indicate that the additional radial airflow improves the coating uniformity, expressed by the relative standard deviation (RSD) value of the dye amount dispersed in the coating layer of each set of pellets. Lower RSD values were noticed in the case of pellets coated using a classic Wurster (CW) chamber equipped with a perforated draft tube (CW-P) compared to the reference experiments conducted with a conventional draft tube; regardless of the air flow rate (105, 130 or 156 m3/h) and the gap size (10 or 20 mm). As demonstrated in our previous studies, swirling inlet airflow (SW) contribute to much more uniform per particle deposition of the coating material when compared to CW process. By utilizing the SW chamber equipped with a modified draft tube (SW-P), the significant improvement in the coating uniformity was achieved at the gap size of 20 mm, regardless of the air flow rate. In the case of additional air flow through the draft tube perforations, additional number of inner tube zones, possessing predominant particle fluctuation frequencies in the range from 1 to 5 Hz, were noted. By utilizing the modified draft tube the lower number of the particle impacts in comparison to coater equipped with the conventional Wurster draft tube were recorded, regardless the coater type.

Design Considerations for the Electrical Power Supply of Future Civil Aircraft with Active High-Lift Systems

Active high-lift systems of future civil aircraft allow noise reduction and the use of shorter runways. Powering high-lift systems electrically have a strong impact on the design requirements for the electrical power supply of the aircraft. The active high-lift system of the reference aircraft design considered in this paper consists of a flexible leading-edge device together with a combination of boundary-layer suction and Coanda-jet blowing. Electrically driven compressors distributed along the aircraft wings provide the required mass flow of pressurized air. Their additional loads significantly increase the electric power demand during take-off and landing, which is commonly provided by electric generators attached to the aircraft engines. The focus of the present study is a feasibility assessment of alternative electric power supply concepts to unburden or eliminate the generator coupled to the aircraft engine. For this purpose, two different concepts using either fuel cells or batteries are outlined and evaluated in terms of weight, efficiency, and technology availability. The most promising, but least developed alternative to the engine-powered electric generator is the usage of fuel cells. The advantages are high power density and short refueling time, compared to the battery storage concept.

Investigation and control of the - to -transition in a novel sub-atmospheric pressure dielectric barrier discharge

A novel flow-driven dielectric barrier discharge concept is presented, which uses a Venturi pump to transfer plasma-generated reactive oxygen and nitrogen species from a sub-atmospheric pressure () discharge region to ambient pressure and can be operated with air. By adjusting the working pressure of the device, the plasma chemistry can be tuned continuously from an ozone ()-dominated mode to a nitrogen oxides ()-only mode. The plasma source is characterized focusing on the mechanisms effecting this mode change. The composition of the device’s output gas was determined using Fourier-transform infrared spectroscopy. The results are correlated to measurements of discharge chamber pressure and temperature as well as of input power. It is found that the mode-change temperature can be controlled by the discharge chamber pressure. The source concept is capable of generating an -dominated plasma chemistry at gas temperatures distinctly below . Through mixing of the processed gas stream with a second flow of pressurized air required for the operation of the Venturi pump, the resulting product gas stream remains close to room temperature. A reduced zero-dimensional reaction kinetics model with only seven reactions is capable of describing the observed pressure- and temperature-dependence of the to mode-change.

A mode transition strategy from air to oxyfuel combustion in a 35 MW coal-fired power plant boiler

The atmosphere under the conditions of a coal combustion reaction in the furnace is the factor that makes the most significant difference during mode transition from traditional air to oxy-fuel combustion. The flue gas is adopted as the primary air and secondary air for pulverized-coal conveying and the support of combustion; it has a high carbon dioxide concentration during the oxy-fuel combustion. The air-leakage reduces CO2 enrichment and leads to thermal NO x production. A control strategy of this shift operation is conducted in a 35MW oxy-fuel combustion power plant boiler by adjusting the furnace pressure, regulating the recirculation rate of the flue gas and amending the oxygen concentration in the inlet stream. The furnace pressure can be changed smoothly and stabilized at a micro-positive level as the pressurized air flow is monitored at a suitable range. The combustion-supporting flue gas is modified by the oxygen content in the furnace outlet, and the circulation rate of the flue gas verifies the regulation process. Results show that the CO2 concentration in the flue gas can be rapidly increased along with the increment of furnace pressure and oxygen in the inlet stream; then, this procedure gradually becomes flattened. The CO2 content in the flue gas correlates with the recirculation rate of the flue gas and oxygen concentration in the inlet stream. The two operation parameters should be maintained at a high CO2 concentration in a range from 0.6-0.7 and 29.5%-30.5%, respectively. Sampling analysis shows that SO2 and NO x emissions were 26 (±1.5) mg/MJ and 90 (±11.7) mg/MJ in air condition, 14 (±0.4) mg/MJ and 34 (±1.6) mg/MJ in oxy-fuel combustion; the burnout rate, mechanical losses of incomplete combustion and the unburned carbon rate remained similar at these two stable combustion modes. This mode transition scheme should provide a reference for monitoring and diagnostics, design and operation control of an oxygen-enriched pulverized-coal combustion power plant boiler.

Effect of nasal continuous positive airway pressure on the pharyngeal swallow in neonates.

Feeding neonates orally while on nasal continuous positive airway pressure (nCPAP) is a common practice. We hypothesize that pressurized airflow provided by nCPAP will alter the swallowing mechanism in neonates, increasing the risk of aspiration during oral feeding. Infants receiving nCPAP with a RAM cannula and tolerating at least 50% of their feeding orally were included in the study (one term; six preterm infants). Each participant underwent a videofluoroscopic swallow study while on nCPAP and off nCPAP. A non-parametric signed-rank test was used for paired data. The incidence of deep penetration (P=0.03) and aspiration (P=0.01) decreased significantly off-nCPAP compared with on-nCPAP. However, the incidence of mild penetration (P=0.65) and nasopharyngeal reflux (P=0.87) remained the same under both conditions. Oral feeding while on-nCPAP significantly increases the risk of laryngeal penetration and tracheal aspiration events. We recommend caution when initiating oral feedings on nCPAP.