scholarly journals Study on PSA Oxygen producing process under plateau region: Effect of purging flow rate on oxygen concentration and recovery

2021 ◽  
Vol 631 ◽  
pp. 012083
Author(s):  
Yaoguo Fu ◽  
Yingshu Liu ◽  
Quanli Zhang ◽  
Xiguang Cao ◽  
Chunyu Zhao
Keyword(s):  
Oxygen Concentration ◽  
Flow Rate ◽  
Plateau Region ◽  
Region Effect

scholarly journals Impact of Electrically Assisted Turbocharger on the Intake Oxygen Concentration and Its Disturbance Rejection Control for a Heavy-duty Diesel Engine

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 3014
Author(s):  
Chao Wu ◽  
Kang Song ◽  
Shaohua Li ◽  
Hui Xie
Keyword(s):  
Oxygen Concentration ◽  
Flow Rate ◽  
Disturbance Rejection ◽  
Air Flow ◽  
Intake Manifold ◽  
Boost Pressure ◽  
Air Flow Rate ◽  
Electrically Assisted ◽  
Disturbance Rejection Control ◽  
Turbine Vane

The electrically assisted turbocharger (EAT) shows promise in simultaneously improving the boost response and reducing the fuel consumption of engines with assist. In this paper, experimental results show that 7.8% fuel economy (FE) benefit and 52.1% improvement in transient boost response can be achieved with EAT assist. EAT also drives the need for a new feedback variable for the air system control, instead of the exhaust recirculation gas (EGR) rate that is widely used in conventional turbocharged engines (nominal system). Steady-state results show that EAT assist allows wider turbine vane open and reduces pre-turbine pressure, which in turn elevates the engine volumetric efficiency hence the engine air flow rate at fixed boost pressure. Increased engine air flow rate, together with the reduced fuel amount necessary to meet the torque demand with assist, leads to the increase of the oxygen concentration in the exhaust gas (EGR gas dilution). Additionally, transient results demonstrate that the enhanced air supply from the compressor and the diluted EGR gas result in a spike in the oxygen concentration in the intake manifold (Xoim) during tip-in, even though there is no spike in the EGR rate response profile. Consequently, there is Nitrogen Oxides (NOx) emission spike, although the response of boost pressure and EGR rate is smooth (no spike is seen). Therefore, in contrast to EGR rate, Xoim is found to be a better choice for the feedback variable. Additionally, a disturbance observer-based Xoim controller is developed to attenuate the disturbances from the turbine vane position variation. Simulation results on a high-fidelity GT-SUTIE model show over 43% improvement in disturbance rejection capability in terms of recovery time, relative to the conventional proportional-integral-differential (PID) controller. This Xoim-based disturbance rejection control solution is beneficial in the practical application of the EAT system.

scholarly journals Modelling and Analysis of the Corrosion Characteristics of Ferritic-Martensitic Steels in Supercritical Water

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 409 ◽  
Author(s):  
Yanhui Li ◽  
Tongtong Xu ◽  
Shuzhong Wang ◽  
Balazs Fekete ◽  
Jie Yang ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Exposure Time ◽  
Flow Rate ◽  
Supercritical Water ◽  
Steel Substrate ◽  
Surface Condition ◽  
Martensitic Steels ◽  
Relative Significance ◽  
Independent Variables ◽  
Linear Relationships

The dependencies of weight gain of 9-12 Cr ferritic-martensitic steels in supercritical water on each of seven principal independent variables (temperature, oxygen concentration, flow rate, exposure time, and key chemical composition and surface condition of steels) have been predicted using a supervised artificial neural network (ANN). The relative significance of each independent variable was uncovered by fuzzy curve analysis, which ranks temperature and exposure time as the most important. The optimized ANN, not only satisfactorily represents the experimentally-known non-linear relationships between the corrosion characteristics of F-M steels and the key independent variables (demonstrating the effectiveness of this technique), but also predicts and reveals that the effects of oxygen concentration on the weight gains, to a certain degree, is influenced by the flow rate and temperature. Finally, according to the ANN predicted-results, departure of oxidation kinetics from the parabolic law, and basic cause of chromium content in steel substrate influencing the corrosion rate, and the synergetic effects of dissolved oxygen concentration, flow rate, and temperature, are discussed and analyzed.

scholarly journals An Analysis of the Performance of a Variable Venturi-type Oxygen Mask

1980 ◽  
Vol 8 (1) ◽  
pp. 44-51 ◽  
Author(s):  
D. F. Woolner ◽  
J. Larkin
Keyword(s):  
Oxygen Concentration ◽  
Flow Rate ◽  
Oxygen Flow Rate ◽  
Oxygen Flow ◽  
Weighted Mean ◽  
Flow Rates ◽  
Oxygen Mask ◽  
Inspired Oxygen ◽  
Theoretical Performance

The theoretical performance of the Hudson Multivent mask is considered. A method is described of determining the flow-weighted mean inspired oxygen concentration produced by the mask. Using this method, it was found that the inspired oxygen concentration was predictable only at the 24% setting using the recommended flow rates, but that increasing the supplied-oxygen flow rates above the recommended levels resulted in the return of predictable function. At settings above 30% predictable function was found to be unlikely, whatever the supplied oxygen flow rate. Recommendations are made regarding the use of this device.

scholarly journals The Effects of Different Levels of Ambient Oxygen in an Oxygen-Enriched Surgical Environment and Production of Surgical Fires

2018 ◽  
Vol 65 (1) ◽  
pp. 3-8 ◽  
Author(s):  
Leah B. Davis ◽  
Mark A. Saxen ◽  
James E. Jones ◽  
James D. McGlothlin ◽  
Juan F. Yepes ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Flow Rate ◽  
Enriched Environment ◽  
Ignition Source ◽  
Latency Time ◽  
Flow Rates ◽  
Ambient Oxygen ◽  
Rate Minimum ◽  
Fire Ignition ◽  
Different Levels

Surgical fires require an oxygen-enriched environment, a flammable substrate, and an ignition source. We hypothesized ambient oxygen concentration is proportional to the latency time to combustion and the incidence of surgical fires that are detected. We examined latency time and number of events, utilizing the VanCleave et al model of intraoral fire ignition under 60, 80, and 100% oxygen concentration and flow rates of 4 and 10 L/min. Results demonstrated that ambient oxygen concentration and flow rate correlated positively to the initiation of combustion. The number of combustion events with 60% oxygen was significantly lower than with both 80% (p = .0168) and 100% (p = .002). Likewise, the number of events with 80% oxygen was significantly lower than with 100% oxygen (p = .0019). Flow rate has a significant effect on the time to the first event (p = .0002), time to first audible pop (p = .0039), and time to first flash or fire (p < .0001). No combustion occurred at oxygen concentrations less than 60% or flows less than 4 L/min. We conclude that latency time to combustion is directly proportional to ambient oxygen concentration and flow rate. Minimum oxygen concentration and flow rate were identified in our model. Further research is indicated to determine the minimal clinical oxygen concentration and flow rate needed to support combustion of an intraoral fire in a patient.

scholarly journals METHOD FOR MEASUREMENT OF GAS PERMEABILITY OF POLYMERIC FILMS

HortScience ◽  
1992 ◽  
Vol 27 (11) ◽  
pp. 1162d-1162
Author(s):  
Sannai Gong ◽  
Kenneth A. Corey
Keyword(s):  
Steady State ◽  
Oxygen Concentration ◽  
Flow Rate ◽  
Gas Permeability ◽  
Modified Atmosphere Packaging ◽  
Polymeric Films ◽  
Steady State Method ◽  
Different Temperatures ◽  
Time Required ◽  
Increasing Temperature

A rapid steady state method for measurement of gas permeability of polymeric films was developed. Films were sealed between two equal volume chambers with pure O2 and pure N2 flowing through opposite sides. Oxygen concentration in the N2 cell was measured over time until steady state was reached. The method was used to determine oxygen permeability of two different films. Results from four replications on each film indicated excellent repeatability with coefficients of variation less than 3%. The time required to reach steady state oxygen concentration was dependent upon film type, flow rate, and temperature. The higher the N2 flow rate the shorter the time to reach steady state O2 concentrations. The slowest measurement at the lowest flow rate of 27 ml/min took less than 3 hours to collect the data necessary to achieve steady state. Increasing temperature from 10°C to 20°C resulted in an approximately 40% increase in O2 permeability for both films tested. The technique will be a valuable tool for measuring permeabilities of new films and the same film at different temperatures, and for selecting the appropriate material for modified atmosphere packaging of fresh produce.

STUDIES ON THE RELATIONSHIP BETWEEN WATER MOVEMENT AND WATER CHEMISTRY IN MIRES

1966 ◽  
Vol 44 (6) ◽  
pp. 747-758 ◽  
Author(s):  
J. H. Sparling
Keyword(s):  
Water Chemistry ◽  
Oxygen Concentration ◽  
Flow Rate ◽  
Water Surface ◽  
Water Movement ◽  
Simple Diffusion ◽  
Flow Rates ◽  
Acidic Conditions ◽  
The Relationship ◽  
Iron And Manganese

Fifty-four sites were selected in a number of mires in Ontario, and rates of water movement were measured on a number of occasions. The rates of water movement ranged from less than 0.1 cm sec−1 to over 8 cm sec−1. The oxygen concentration of the mire waters increased with increasing flow rate, approaching saturation at rates over 1 cm sec−1. From a model it was shown that at a flow rate of less than 0.3–0.4 cm sec−1 the diffusion of oxygen into the water would be similar to simple diffusion into a stationary water surface, and because of the respiration of roots and microorganisms in the peat, the oxygen would tend to be depleted. Above flow rates of 0.4 cm sec−1 the water is agitated, and is continually replenished with oxygen from the atmosphere. Reduced states of iron and manganese were shown to be in solution at concentrations greater than 0.1 mg/1 only at low rates of water flow. The pH was also shown to increase with faster rates of water movement, the increase depending on the base status of the mire. Aluminium is in solution only in situations of low water movement where more acidic conditions are prevalent.

scholarly journals Correlation between air flow rate and pollutant concentrations during two-stage oak log combustion in a 25 KW residential boiler

2016 ◽  
Vol 37 (3) ◽  
pp. 419-428
Author(s):  
Marek Juszczak
Keyword(s):  
Carbon Monoxide ◽  
Nitrogen Oxide ◽  
Oxygen Concentration ◽  
Flow Rate ◽  
Flue Gas ◽  
Air Flow ◽  
Air Flow Rate ◽  
Pollutant Concentrations ◽  
Oxide Concentration ◽  
Nitrogen Oxide Concentration

Abstract It can be expected that there is a considerable correlation between combustion air flow rate and the concentrations of carbon monoxide, hydrocarbons and nitrogen oxide in the flue gas. The influence of temperature and oxygen concentration in the combustion zone on the concentrations of carbon monoxide, hydrocarbons and nitrogen oxide in the flue gas, for high and low combustion air flow, was analysed. Oxygen concentration for which the concentration of carbon monoxide is the lowest was determined, as well as the mutual relation between carbon monoxide and nitrogen oxide concentration.

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