scholarly journals Experimental Investigation and Mathematical Modelling of Pressure Transfer Function for Air Compressor

2018 ◽  
Vol 7 (4.19) ◽  
pp. 950
Author(s):  
Mishaal A. AbdulKareem
Keyword(s):  
Pressure Response ◽  
Compressed Air ◽  
Operating Pressure ◽  
Perfect Gas ◽  
Cross Sectional ◽  
Air Compressor ◽  
Output Pressure ◽  
Sinusoidal Functions ◽  
Good Agreement ◽  
Pressure Switch

A mathematical model is developed to estimate the pressure response of an insulated electric air compressor. A pressure switch is modeled as a comparator and the electric motor as an amplifier. It is assumed that the compressed air is a perfect gas when applying the isentropic process. In addition, the effect of a step, ramp and sinusoidal functions of disturbance signals on the air pressure has been studied.  A good agreement was obtained when comparing the predicted results with the measured values obtained from the experimental test that was done using a (1.32 kW, 23 litter and 8 bar) electric reciprocating air compressor. In addition, the same behavior of the predicted results was obtained when compared with results of a previously published article. It was found that the time constant of this control system is directly proportional with the value of the spring constant that is inserted inside the pressure switch and with the volume of air storage vessel, and it is inversely proportional with the gain of the amplifier and with the effective cross-sectional area of the pressure switch diaphragm and it is independent of the value of operating pressure set point. In addition, when the value of disturbance signal is positive, it will increase the output pressure response and when it is negative, it will decrease it. 

scholarly journals Cold bubble humidification of low-flow oxygen does not prevent acute changes in inflammation and oxidative stress at nasal mucosa

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lauriana Alves Santana ◽  
Suellen Karoline Moreira Bezerra ◽  
Beatriz Mangueira Saraiva-Romanholo ◽  
Wellington Pereira Yamaguti ◽  
Iolanda de Fátima Lopes Calvo Tibério ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Nasal Mucosa ◽  
Oxygen Therapy ◽  
Mucociliary Clearance ◽  
Nasal Cannula ◽  
Compressed Air ◽  
Low Flow ◽  
Cross Sectional ◽  
Nasal Symptoms ◽  
Nasal Inflammation

AbstractSome clinical situations require the use of oxygen therapy for a few hours without hypoxemia. However, there are no literature reports on the effects of acute oxygen therapy on the nasal mucosa. This study aimed to evaluate the acute effects of cold bubble humidification or dry oxygen on nasal Inflammation, oxidative stress, mucociliary clearance, and nasal symptoms. This is a randomized controlled cross-sectional study in which healthy subjects were randomly allocated into four groups: (1) CA + DRY (n = 8): individuals receiving dry compressed air; (2) OX + DRY (n = 8): individuals receiving dry oxygen therapy; (3) CA + HUMID (n = 7): individuals receiving cold bubbled humidified compressed air; (4) OX + HUMID (n = 8): individuals receiving cold bubbled humidified oxygen therapy. All groups received 3 L per minute (LPM) of the oxygen or compressed air for 1 h and were evaluated: total and differential cells in the nasal lavage fluid (NLF), exhaled nitric oxide (eNO), 8-iso-PGF2α levels, saccharin transit test, nasal symptoms, and humidity of nasal cannula and mucosa. Cold bubble humidification is not able to reduced nasal inflammation, eNO, oxidative stress, mucociliary clearance, and nasal mucosa moisture. However, subjects report improvement of nasal dryness symptoms (P < 0.05). In the conclusion, cold bubble humidification of low flow oxygen therapy via a nasal cannula did not produce any effect on the nasal mucosa and did not attenuate the oxidative stress caused by oxygen. However, it was able to improve nasal symptoms arising from the use of oxygen therapy.

scholarly journals 3D-Volume Rendering of the Pelvis with Emphasis on Paraurethral Structures Based on MRI Scans and Comparisons between 3D Slicer and OsiriX®

2021 ◽  
Vol 45 (3) ◽  
Author(s):  
C. M. Durnea ◽  
S. Siddiqi ◽  
D. Nazarian ◽  
G. Munneke ◽  
P. M. Sedgwick ◽  
...  
Keyword(s):  
Image Processing ◽  
Secondary Analysis ◽  
Three Dimensional ◽  
3D Models ◽  
Clinical Role ◽  
Cross Sectional ◽  
3D Slicer ◽  
Mri Scans ◽  
3D Volume ◽  
Good Agreement

AbstractThe feasibility of rendering three dimensional (3D) pelvic models of vaginal, urethral and paraurethral lesions from 2D MRI has been demonstrated previously. To quantitatively compare 3D models using two different image processing applications: 3D Slicer and OsiriX. Secondary analysis and processing of five MRI scan based image sets from female patients aged 29–43 years old with vaginal or paraurethral lesions. Cross sectional image sets were used to create 3D models of the pelvic structures with 3D Slicer and OsiriX image processing applications. The linear dimensions of the models created using the two different methods were compared using Bland-Altman plots. The comparisons demonstrated good agreement between measurements from the two applications. The two data sets obtained from different image processing methods demonstrated good agreement. Both 3D Slicer and OsiriX can be used interchangeably and produce almost similar results. The clinical role of this investigation modality remains to be further evaluated.

Research on a Novel Miniature Air Compressor Generating both Compressed Air and Vacuum

2014 ◽  
Vol 1027 ◽  
pp. 253-256
Author(s):  
Jian Hai Han ◽  
Jie Zhang ◽  
Dong Liao Fu ◽  
Zhi Gang Hu
Keyword(s):  
Vacuum Pump ◽  
Operating Principle ◽  
Experimental Results ◽  
System Structure ◽  
Compressed Air ◽  
The Novel ◽  
Pump Mode ◽  
Air Compressor

A new kind of miniature air compressor is proposed in this paper. This compressor can produce both compressed air and vacuum. The system structure, operating principle and experimental characteristics of the novel miniature air compressor are described in detail. The experimental results prove that the shift between air compressor mode and vacuum pump mode is possible and the design of system structure is appropriate.

Torsional Stiffness of a Thin-Walled Beam Braced by Pinned or Rigidly Fixed Transverse Diaphragms

1973 ◽  
Vol 15 (5) ◽  
pp. 351-356
Author(s):  
T. Harrison ◽  
J. M. Siddall
Keyword(s):  
Experimental Evidence ◽  
Theoretical Work ◽  
Torsional Stiffness ◽  
Cross Sectional ◽  
Cross Sectional Profile ◽  
Thin Walled ◽  
Sectional Profile ◽  
Good Agreement

The torsional stiffness of a thin-walled beam of open cross-sectional profile braced by evenly spaced transverse diaphragms is studied. Diaphragms rigidly fixed or attached by frictionless pins are treated and it is seen that, in either case, the only effect is to modify the St Venant torsional constant for the thin-walled beam. The theoretical work is supported by experimental evidence from two braced perspex channels which simulate the two assumed methods of attaching the diaphragms. Good agreement is demonstrated.

Loss analysis of the shrouded radial-inflow turbine for compressed air energy storage

2020 ◽  
pp. 095765092094784
Author(s):  
Ziyi Shao ◽  
Wen Li ◽  
Aiting Li ◽  
Xing Wang ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Energy Storage ◽  
Entropy Generation ◽  
Velocity Ratio ◽  
Compressed Air ◽  
Compressed Air Energy Storage ◽  
Suction Surface ◽  
Loss Mechanism ◽  
Cross Sectional ◽  
Radial Turbine ◽  
Radial Inflow Turbine

The shrouded radial-inflow turbine is widely employed as a power generation device in the compressed air energy storage (CAES) system. The loss mechanism and off-designed performance of the shrouded radial turbine are lesser known hitherto and should be deeply understood. Loss analyses of a shrouded radial turbine are conducted numerically based on the first and second laws of thermodynamics in the current study. The relationship between losses and the secondary flow has been discussed in detail. A high proportion of loss in the rotor and outblock passage is found under off-designed conditions. The secondary vortex cores and wake are the primary sources of energy dissipation, while the entropy generation mainly appears at the edge of secondary vortices. The suction-surface separation expands as the velocity ratio is decreased, making the high entropy generation scope on the cross-sectional plane wider. Reducing the seal clearance and avoiding the low velocity ratio conditions are quite necessary to reduce losses. It is recommended the outlet passage should be designed longer than the length of rotor axial chord for a uniform outflow.

Application of Bond-Graph Method in Microjet Engine Cold Start Modeling to Investigate the Idea of Injecting Compressed Air

2015 ◽  
Vol 799-800 ◽  
pp. 890-894 ◽  
Author(s):  
Morteza Montazeri-Gh ◽  
Seyed Alireza Miran-F
Keyword(s):  
Bond Graph ◽  
Compressed Air ◽  
Labview Software ◽  
Cold Starting ◽  
Graph Modeling ◽  
Start Up ◽  
Proposed Model ◽  
Bond Graph Modeling ◽  
Starting Process ◽  
Good Agreement

This paper presents the application of bond-graph modeling for investigation of the microjet engine in cold starting mode. In this model, the idea of simultaneous usage of the compressed air and electric starter is developed to perform the starting process. For this purpose, the microjet engine is assembled by components which is provided by the engine manufacturer, then a monitoring system in Labview software is developed. Dynamic modeling of the engine cold starting phase is performed by bond graph approach and simulated in 20-sim software. So, the allowable air pressure to inject during the starting process is calculated. The simulation results are then compared with experimental data where a good agreement is observed. These results support the proposed model for further analysis to improve the performance of engine start-up process.

A Hybrid Model for Predicting Gas Entrainment in a Small Branch From a Co-Current Flowing Gas-Liquid Regime

2010 ◽  
Author(s):  
Robert Bowden ◽  
Wael Saleh ◽  
Ibrahim Hassan
Keyword(s):  
Digital Imaging ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Critical Conditions ◽  
Inertial Effects ◽  
Cross Sectional ◽  
Gas Entrainment ◽  
Small Branch ◽  
Dip Angle ◽  
Good Agreement

An analytical model was developed to predict the critical conditions at the onset of gas entrainment in a single downward oriented branch. The branch was installed on a horizontal square cross-sectional channel having a smooth stratified co-currently flowing gas-liquid regime in the upstream inlet region. The branch flow was simulated as a three-dimensional point-sink while the downstream run flow was treated with a uniform velocity at the critical dip location. A boundary condition was imposed in the model whereby the flow distribution between the branch and run was obtained experimentally and digital imaging was used to quantify the critical dip location through the dip angle. Three constant dip angles were evaluated in the model and results showed the dip height to have good agreement with experiments between angles of 50 and 60 degrees. The predicted upstream height, however, did not match well with the experimentally determined height due to the omission of shear and inertial effects between the upstream location and critical dip.

Energy Consumption and Energy Saving Research Status of Air Compressor System

2014 ◽  
Vol 628 ◽  
pp. 225-228
Author(s):  
Xiao Lin Tian ◽  
Shou Gen Hu ◽  
Hong Bo Qin ◽  
Jun Zhao ◽  
Ling Yuan Ran
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Energy Saving ◽  
Compressed Air ◽  
Efficiency Evaluation ◽  
Air Compressor ◽  
Research Status ◽  
Air System ◽  
Energy Efficiency Evaluation ◽  
At Home

As the most widely used fourth energy, compressed air system has high operating costs. The research about energy consumption and energy optimization measures of compressed air system has become the new field to achieve energy saving among countries all over the world. In recent years, air compressor system researches in energy consumption, influence factors, energy saving technologies and energy efficiency evaluation have been carried out at home and abroad, and some achievements have been achieved. This paper summarizes energy consumption research status of air compressor system at home and abroad, and energy-saving technologies of compressed air in generation link, treatment link and gas link, and energy efficiency evaluation methods for of air compressor systems. Potentials and drawbacks of current researches are analyzed simultaneously. In the end energy-saving development directions of air compressor system are predicted.

Vibration of a Rotating Asymmetric Shaft Supported in Asymmetric Bearings

1968 ◽  
Vol 10 (3) ◽  
pp. 252-261 ◽  
Author(s):  
H. F. Black ◽  
A. J. McTernan
Keyword(s):  
Natural Frequencies ◽  
Equations Of Motion ◽  
Forced Vibrations ◽  
Variation Method ◽  
Approximate Theory ◽  
Cross Sectional ◽  
Mass Unbalance ◽  
The Mean ◽  
Theoretical Results ◽  
Good Agreement

The parametrically excited vibrations of this system with assumed small asymmetry of the shaft cross-section are discussed in terms of the motion of a symmetric shaft having the mean cross-sectional flexibility, and the equations of motion are solved by the approximate perturbation-variation method of Hsu. Both features yield a more lucid appreciation of the motions expected than previous treatments: in particular, simpler explicit expressions for unstable bounds are given and forced vibrations due to mass unbalance are discussed with greater facility. The practically important case of nearly coincident natural frequencies is examined. The theoretical results are compared with analogue computation: good agreement with the approximate theory is found even for quite large shaft asymmetry.

Sign in / Sign up

Export Citation Format

Share Document