EFFECTS ON BREATHING MECHANICS AND GAS EXCHANGE OF DIFFERENT INSPIRATORY GAS FLOW PATTERNS IN PATIENTS UNDERGOING RESPIRATOR TREATMENT

1976 ◽  
Vol 20 (2) ◽  
pp. 102
Author(s):  
H. JOHANSSON
Keyword(s):  
Gas Exchange ◽  
Gas Flow ◽  
Flow Patterns ◽  
Breathing Mechanics

Gas and solids motion around deformed and interacting bubbles in fluidized beds

1972 ◽  
Vol 51 (1) ◽  
pp. 187-205 ◽  
Author(s):  
R. Clift ◽  
J. R. Grace ◽  
L. Cheung ◽  
T. H. Do
Keyword(s):  
Particle Motion ◽  
Fluidized Beds ◽  
Gas Flow ◽  
Theoretical Models ◽  
Flow Patterns

Previous analyses of gas and particle motion around bubbles in fluidized beds have concentrated on idealized isolated bubbles. In this paper three non-idealities are considered using the theoretical models of Davidson and Murray. Gas flow patterns are derived for indented and elongated bubbles and for pairs of interacting bubbles. Cloud boundaries are predicted for these situations and some effects on gas-solid contacting are discussed.

scholarly journals NMR Analysis Method of Gas Flow Pattern in the Process of Shale Gas Depletion Development

Geofluids ◽  
2022 ◽  
Vol 2022 ◽  
pp. 1-7
Author(s):  
Rui Shen ◽  
Zhiming Hu ◽  
Xianggang Duan ◽  
Wei Sun ◽  
Wei Xiong ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Pore Pressure ◽  
Shale Gas ◽  
Gas Flow ◽  
Continuous Medium ◽  
Slip Flow ◽  
Flow Patterns ◽  
Transitional Flow ◽  
Analysis Method ◽  
Adsorbed Gas

Shale gas reservoirs have pores of various sizes, in which gas flows in different patterns. The coexistence of multiple gas flow patterns is common. In order to quantitatively characterize the flow pattern in the process of shale gas depletion development, a physical simulation experiment of shale gas depletion development was designed, and a high-pressure on-line NMR analysis method of gas flow pattern in this process was proposed. The signal amplitudes of methane in pores of various sizes at different pressure levels were calculated according to the conversion relationship between the NMR T 2 relaxation time and pore radius, and then, the flow patterns of methane in pores of various sizes under different pore pressure conditions were analyzed as per the flow pattern determination criteria. It is found that there are three flow patterns in the process of shale gas depletion development, i.e., continuous medium flow, slip flow, and transitional flow, which account for 73.5%, 25.8%, and 0.7% of total gas flow, respectively. When the pore pressure is high, the continuous medium flow is dominant. With the gas production in shale reservoir, the pore pressure decreases, the Knudsen number increases, and the pore size range of slip flow zone and transitional flow zone expands. When the reservoir pressure is higher than the critical desorption pressure, the adsorbed gas is not desorbed intensively, and the produced gas is mainly free gas. When the reservoir pressure is lower than the critical desorption pressure, the adsorbed gas is gradually desorbed, and the proportion of desorbed gas in the produced gas gradually increases.

Influence of CGD structure on burden descending behavior in COREX shaft furnace

2019 ◽  
Vol 116 (3) ◽  
pp. 304 ◽  
Author(s):  
Xingsheng Zhang ◽  
Zongshu Zou ◽  
Zhiguo Luo
Keyword(s):  
Large Scale ◽  
Gas Flow ◽  
Shaft Furnace ◽  
Three Dimensional ◽  
Interaction Force ◽  
Flow Patterns ◽  
Solid Flow ◽  
Reducing Gas ◽  
A New Technique ◽  
Actual Size

For improving the reducing gas flow in the center of a large-scale shaft furnace, the central gas distribution (CGD) device, a new technique, is proposed and installed in the shaft furnace. Because of its less-developed history, the solid flow in the shaft furnace with CGD is unclear. In this work, a three-dimensional cylindrical model of COREX-3000 shaft furnace in actual size is established based on DEM. Four types of burden, including pellet, lump ore, coke and flux, are taken into consideration in the model. The model is validated by experiment and then it is used to investigate the influence of CGD structure on solid flow patterns, burden descending velocity, interaction force and abrasive wear. The results show that the CGD structure has some effects on the solid flow patterns and burden descending velocity. As the CGD diameter increases, the interaction force between particles is decreased but the total abrasion energy on CGD is increased. As the CGD height increases, both the interaction force between particles and the total abrasion energy on CGD are decreased.

scholarly journals Gas exchange during exercise in habitually active asthmatic subjects

2005 ◽  
Vol 99 (5) ◽  
pp. 1938-1950 ◽  
Author(s):  
H. C. Haverkamp ◽  
J. A. Dempsey ◽  
J. D. Miller ◽  
L. M. Romer ◽  
D. F. Pegelow ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Airway Inflammation ◽  
Lung Volume ◽  
Ventilatory Response ◽  
Forced Expiratory Volume ◽  
Airflow Limitation ◽  
Expiratory Flow Limitation ◽  
Mechanical Constraints ◽  
Breathing Mechanics ◽  
Exercise Induced

We determined the relations among gas exchange, breathing mechanics, and airway inflammation during moderate- to maximum-intensity exercise in asthmatic subjects. Twenty-one habitually active (48.2 ± 7.0 ml·kg−1·min−1 maximal O2 uptake) mildly to moderately asthmatic subjects (94 ± 13% predicted forced expiratory volume in 1.0 s) performed treadmill exercise to exhaustion (11.2 ± 0.15 min) at ∼90% of maximal O2 uptake. Arterial O2 saturation decreased to ≤94% during the exercise in 8 of 21 subjects, in large part as a result of a decrease in arterial Po2 (PaO2): from 93.0 ± 7.7 to 79.7 ± 4.0 Torr. A widened alveolar-to-arterial Po2 difference and the magnitude of the ventilatory response contributed approximately equally to the decrease in PaO2 during exercise. Airflow limitation and airway inflammation at baseline did not correlate with exercise gas exchange, but an exercise-induced increase in sputum histamine levels correlated with exercise PaO2 (negatively) and alveolar-to-arterial Po2 difference (positively). Mean pulmonary resistance was high during exercise (3.4 ± 1.2 cmH2O·l−1·s) and did not increase throughout exercise. Expiratory flow limitation occurred in 19 of 21 subjects, averaging 43 ± 35% of tidal volume near end exercise, and end-expiratory lung volume rose progressively to 0.25 ± 0.47 liter greater than resting end-expiratory lung volume at exhaustion. These mechanical constraints to ventilation contributed to a heterogeneous and frequently insufficient ventilatory response; arterial Pco2 was 30–47 Torr at end exercise. Thus pulmonary gas exchange is impaired during high-intensity exercise in a significant number of habitually active asthmatic subjects because of high airway resistance and, possibly, a deleterious effect of exercise-induced airway inflammation on gas exchange efficiency.

Respiratory and inert gas exchange during high-frequency ventilation

1982 ◽  
Vol 52 (3) ◽  
pp. 683-689 ◽  
Author(s):  
H. T. Robertson ◽  
R. L. Coffey ◽  
T. A. Standaert ◽  
W. E. Truog
Keyword(s):  
Gas Exchange ◽  
High Frequency ◽  
Gas Flow ◽  
Inert Gases ◽  
Inert Gas ◽  
High Frequency Ventilation ◽  
Physiological Dead Space ◽  
Volume Ventilation ◽  
Frequency Ventilation ◽  
Carrier Gases

Pulmonary gas exchange during high-frequency low-tidal volume ventilation (HFV) (10 Hz, 4.8 ml/kg) was compared with conventional ventilation (CV) and an identical inspired fresh gas flow in pentobarbital-anesthetized dogs. Comparing respiratory and infused inert gas exchange (Wagner et al., J. Appl. Physiol. 36: 585--599, 1974) during HFV and CV, the efficiency of oxygenation was not different, but the Bohr physiological dead space ratio was greater on HFV (61.5 +/- 2.2% vs. 50.6 +/- 1.4%). However, the elimination of the most soluble inert gas (acetone) was markedly enhanced by HFV. The increased elimination of the soluble infused inert gases during HFV compared with CV may be related to the extensive intraregional gas mixing that allows the conducting airways to serve as a capacitance for the soluble inert gases. Comparing as exchange during HFV with three different density carrier gases (He, N2, and Ar), the efficiency of elimination of Co2 or the intravenously infused inert gases was greatest with He-O2. However, the alveolar-arterial partial pressure difference for O2 on He-O2 exceeded that on N2-O2 by 5.4 Torr during HFV. The finding agrees with similar observations during CV, suggesting that this aspect of gas exchange is not substantially altered by HFV.

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