Bird Respiration: Flow Patterns in the Duck Lung

1971 ◽  
Vol 54 (1) ◽  
pp. 103-118 ◽  
Author(s):  
WILLIAM L. BRETZ ◽  
KNUT SCHMIDT-NIELSEN
Keyword(s):  
Heat Load ◽  
Air Flow ◽  
Body Temperatures ◽  
Exchange System ◽  
Direct Route ◽  
Unidirectional Flow ◽  
Air Sacs ◽  
Flow Directions ◽  
Air Flows ◽  
Counter Current

1. A heated thermistor probe was designed to determine the direction of air flow in the respiratory system of birds. The probes did not significantly affect the respiratory rates, tidal volumes, or body temperatures of birds implanted with the probes as compared to unimplanted birds. 2. Air-flow directions were determined in the primary bronchus, the craniomedial secondary bronchi, and the caudodorsal secondary bronchi in the lungs of ducks which were either unanaesthetized and at rest, anaesthetized, or panting due to heat load. 3. The recorded air-flow directions suggested the following patterns of air flow in the duck lung for resting respiration. During inspiration air flows to the posterior air sacs directly from the primary bronchus (the most direct route), without passing through the tertiary bronchi, while air flows towards the anterior air sacs via the caudodorsal secondary bronchi and the tertiary bronchi (thus by-passing the most direct route, the craniomedial secondary bronchi connecting these sacs to the primary bronchus). During expiration air flows from the anterior sacs to the primary bronchus via the craniomedial secondary bronchi (the most direct route), but from the posterior sacs through the tertiary bronchi and through branches of the craniomedial secondary bronchi to the primary bronchus (by-passing the most direct route, the portion of the mesobronchus posterior to the craniomedial bronchi). 4. The patterns established for panting and anaesthetized respiration were very similar to those described for resting respiration. There was no indication of an effective shunt operating during panting to avoid excessive ventilation of the exchange surfaces of the lung. 5. Flow in the tertiary bronchi appeared to be in the same direction during both inspiration and expiration (from the caudodorsal secondary bronchi towards the craniomedial secondary bronchi). Such unidirectional flow would permit the operation of a counter-current exchange system, provided that the blood vessels are arranged appropriately around the parabronchi.

scholarly journals Fluid mechanical valving of air flow in bird lungs

1988 ◽  
Vol 136 (1) ◽  
pp. 1-12 ◽  
Author(s):  
D. O. Kuethe
Keyword(s):  
High Pressure ◽  
Flow Rate ◽  
Pressure Difference ◽  
Air Flow ◽  
Low Pressure ◽  
Physical Models ◽  
Unidirectional Flow ◽  
Air Sacs ◽  
Caudal Portion ◽  
Flow Through

The unidirectional flow through the gas-exchanging bronchi of bird lungs is known to be effected by (1) the structure of the major bronchi and (2) a pressure difference between the cranial and caudal air sacs. To study the effects of bronchial structure, simple physical models of bird lungs were constructed. They suggested that, to achieve unidirectional flow, air in the caudal portion of the primary bronchus must be directed towards the orifices of the mediodorsal bronchi. To study the effect of air sac pressures, a controllable pressure difference was produced between the air sac orifices of fixed duck lungs. The cranial orifices had a higher pressure than the caudal ones during inhalation and vice versa during exhalation. There was a set of pressure differences for which the paleopulmo received the same flow rate during inhalation as during exhalation. High pressure differences caused more flow in the paleopulmo during exhalation than during inhalation; low pressure differences had the converse effect.

COMBUSTION BEHAVIOR OF LUMPY COKE IN PACKED BED IN A COUNTER CURRENT AIR FLOW

2018 ◽  
Author(s):  
Bassem Hallak ◽  
N. Linn ◽  
Eckehard Specht ◽  
Fabian Herz
Keyword(s):  
Air Flow ◽  
Packed Bed ◽  
Combustion Behavior ◽  
Counter Current

Thermodynamic Estimate of Minimal Dissipation for Heat Exchange System

2008 ◽  
Author(s):  
Andrei A. Akhremenkov ◽  
Anatoliy M. Tsirlin ◽  
Vladimir Kazakov
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Load ◽  
Point Of View ◽  
Exchange System ◽  
Heat Exchange System ◽  
Heat Exchange Surface ◽  
Minimal Dissipation ◽  
The Difference ◽  
Exchange Surface

In this paper we consider heat exchange system from point of view of Finite-time thermodynamics. At first time the novel estimate of the minimal entropy production in a general-type heat exchange system with given heat load and fixed heat exchange surface is derived. The corresponding optimal distribution of heat exchange surface and optimal contact temperatures are also obtained. It is proven that if a heat flow is proportional to the difference of contacting flows’ temperatures then dissipation in a multi-flow heat exchanger is minimal only if the ratio of contact temperatures of any two flows at any point inside heat exchanger is the same and the temperatures of all heating flows leaving exchanger are also the same. Our result based on those assumptions: 1. heat transfer law is linear (17); 2. summary exchange surface is given; 3. heat load is given; 4. input tempretures for all flows are given; 5. water equivalents for all flows are given.

scholarly journals Influence of air velocity on indoor environment quality in unidirectional flow operating theatres: A study based on Computational Fluid Dynamics

2019 ◽  
Vol 85 ◽  
pp. 02003
Author(s):  
Gonzalo Sánchez-Barroso Moreno ◽  
Justo García Sanz-Calcedo ◽  
Alfonso C. Marcos Romero
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Performance ◽  
Indoor Environment ◽  
Air Flow ◽  
Environment Quality ◽  
Hospital Facility ◽  
Unidirectional Flow ◽  
Indoor Environment Quality ◽  
Operating Theatres

It is necessary to characterise air-conditioning airflow in omanuscriprder to optimize hospital Indoor Environment Quality in high-performance operating theatres, and also reduce the risk of nosocomial infection due to pathogen contamination. The aim of this article is to study the prevalence of optimal healthy conditions from controlled air flow quality in hospital facilities, and to minimize energy consumption. To this purpose, the indoor air movement was modelled by Computational Fluid Dynamics technology. The optimal results showed that it is necessary to drive ultra-clean air ranging between 0.25 m/s and 0.40 m/s, values which are adequate to perform efficient sweeping and cleaning of the air near the patient, maintaining unidirectional air flow permanently as the air passes through the surgical field. These speeds must be taken into account as calculation parameters in new hospital facility projects, and as control parameters for the existing operating theatres.

Thermoregulatory effects of abdominal air sacs on spermatogenesis in domestic fowl

1960 ◽  
Vol 198 (6) ◽  
pp. 1343-1345 ◽  
Author(s):  
Reginald A. Herin ◽  
Nicholas H. Booth ◽  
Robert M. Johnson
Keyword(s):  
Domestic Fowl ◽  
Semen Quality ◽  
Cooling Effect ◽  
Germinal Epithelium ◽  
Body Temperatures ◽  
High Body ◽  
Air Sacs ◽  
Significant Difference ◽  
Normal Spermatogenesis

In an attempt to determine if the posterior abdominal air sacs exert a cooling effect on the testes of the domestic rooster, thereby facilitating normal spermatogenesis, the air sacs were surgically removed and the testes insulated with surgical cotton. No significant difference was found in the semen quality between the control and experimental groups. Comparison of the testicular, air sac and rectal temperatures showed no significant differences. It is suggested that the air sacs do not cool the testes of the rooster and that the germinal epithelium of the rooster has adapted to the high body temperatures and produces normal spermatozoa at this temperature.

scholarly journals CFD study on the effects of boundary conditions on air flow through an air-cooled condenser

2018 ◽  
Vol 180 ◽  
pp. 02103
Author(s):  
Zdeněk Sumara ◽  
Michal Šochman
Keyword(s):  
Velocity Field ◽  
Boundary Conditions ◽  
Air Flow ◽  
Virtual Model ◽  
Numerical Schemes ◽  
Rans Equations ◽  
Uniform Velocity ◽  
Flow Through ◽  
Air Flows ◽  
Turbulent Models

This study focuses on the effects of boundary conditions on effectiveness of an air-cooled condenser (ACC). Heat duty of ACC is very often calculated for ideal uniform velocity field which does not correspond to reality. Therefore, this study studies the effect of wind and different landscapes on air flow through ACC. For this study software OpenFOAM was used and the flow was simulated with the use of RANS equations. For verification of numerical setup a model of one ACC cell with dimensions of platform 1.5×1.5 [m] was used. In this experiment static pressures behind fan and air flows through a model of surface of condenser for different rpm of fan were measured. In OpenFOAM software a virtual clone of this experiment was built and different meshes, turbulent models and numerical schemes were tested. After tuning up numerical setup virtual model of real ACC system was built. Influence of wind, landscape and height of ACC on air flow through ACC has been investigated.

Raised Floor Hybrid Cooled Data Center: Effect on Rack Inlet Air Temperatures When In Row Cooling Units are Installed Between the Racks

2015 ◽  
Author(s):  
Tianyi Gao ◽  
James Geer ◽  
Russell Tipton ◽  
Bruce Murray ◽  
Bahgat G. Sammakia ◽  
...  
Keyword(s):  
Flow Rate ◽  
Data Center ◽  
Heat Load ◽  
Data Centers ◽  
Cooling System ◽  
Air Flow ◽  
Inlet Temperature ◽  
Air Flow Rate ◽  
Air Temperatures ◽  
Cooling Unit

The heat dissipated by high performance IT equipment such as servers and switches in data centers is increasing rapidly, which makes the thermal management even more challenging. IT equipment is typically designed to operate at a rack inlet air temperature ranging between 10 °C and 35 °C. The newest published environmental standards for operating IT equipment proposed by ASHARE specify a long term recommended dry bulb IT air inlet temperature range as 18°C to 27°C. In terms of the short term specification, the largest allowable inlet temperature range to operate at is between 5°C and 45°C. Failure in maintaining these specifications will lead to significantly detrimental impacts to the performance and reliability of these electronic devices. Thus, understanding the cooling system is of paramount importance for the design and operation of data centers. In this paper, a hybrid cooling system is numerically modeled and investigated. The numerical modeling is conducted using a commercial computational fluid dynamics (CFD) code. The hybrid cooling strategy is specified by mounting the in row cooling units between the server racks to assist the raised floor air cooling. The effect of several input variables, including rack heat load and heat density, rack air flow rate, in row cooling unit operating cooling fluid flow rate and temperature, in row coil effectiveness, centralized cooling unit supply air flow rate, non-uniformity in rack heat load, and raised floor height are studied parametrically. Their detailed effects on the rack inlet air temperatures and the in row cooler performance are presented. The modeling results and corresponding analyses are used to develop general installation and operation guidance for the in row cooler strategy of a data center.

Study on Countercurrent Flow in a PWR Hot Leg Under Reflux Cooling

2010 ◽  
Author(s):  
Noritoshi Minami ◽  
Michio Murase ◽  
Akio Tomiyama
Keyword(s):  
Numerical Simulations ◽  
Flow Pattern ◽  
Flow Rate ◽  
Current Flow ◽  
Air Flow ◽  
Flow Patterns ◽  
Interfacial Friction ◽  
Air Flow Rate ◽  
Counter Current Flow ◽  
Counter Current

In this paper, results of experiments and numerical simulations for counter-current flow in a pressurized water reactor hot leg under reflux cooling are summarized. In the experiments, we used two types of small scale PWR hot legs. One was a 1/5th scale rectangular duct, and the other was a 1/15th scale circular pipe. Air and water were used for gas and liquid phases. The air flow rate and the supplied water flow rate were varied to observe flow pattern and measure the counter-current flow limitation (CCFL) characteristics. Flow patterns in the elbow and the inclined section were strongly affected by those in the horizontal section. In the 1/15th scale circular pipe experiments, CCFL characteristics obtained by increasing the air flow rate differed from those obtained by decreasing it. CCFL characteristics corresponded to the flow pattern transition. In the numerical simulations, we used a three-dimensional two-fluid model to evaluate the capability of predicting counter-current flow in the hot leg. Good agreements between measured and predicted flow patterns and CCFL characteristics were obtained by using an appropriate set of correlations for interfacial friction coefficient. We also carried out simulations of actual hot leg conditions to examine the effects of fluid properties and size. Predicted flow patterns and CCFL characteristics were close to those of scale model calculations. We concluded the combination of calculation model and interfacial friction coefficients used in this study can predict the counter-current flow in a hot leg.

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