scholarly journals Circulatory heat sources for canine respiratory heat exchange.

1986 ◽  
Vol 78 (4) ◽  
pp. 1015-1019 ◽  
Author(s):  
J Solway ◽  
A R Leff ◽  
I Dreshaj ◽  
N M Munoz ◽  
E P Ingenito ◽  
...  
Keyword(s):  
Heat Exchange ◽  
Heat Sources ◽  
Respiratory Heat Exchange

Role of respiratory heat exchange in production of exercise-induced asthma

1979 ◽  
Vol 46 (3) ◽  
pp. 467-475 ◽  
Author(s):  
E. C. Deal ◽  
E. R. McFadden ◽  
R. H. Ingram ◽  
R. H. Strauss ◽  
J. J. Jaeger
Keyword(s):  
Heat Exchange ◽  
Thermal Load ◽  
Tracheobronchial Tree ◽  
Total Heat Flux ◽  
Random Fashion ◽  
Theoretical Predictions ◽  
Per Se ◽  
Exercise Induced ◽  
Respiratory Heat Exchange

We have hypothesized that it is the total heat flux in the tracheobronchial tree during exercise that determines the degree of postexertional obstruction in asthma, and have developed quanititative expressions that relate these two events. We tested this hypothesis by comparing the observed responses to exercise, while our subjects inhaled dry air at various temperatures ranging from subzero to 80 degrees C in a random fashion, to those that we predicted would occur based upon calculations of respiratory heat exchange. We further determined if heat could be transferred from the inspired air to the mucosa so as to offset evaporative losses from the airways. The observed responses fell as air temperature was increased from -11 to +37 degrees C and exactly matched theoretical predictions. Above 37 degrees C, the observed response exceeded predictions, indicating that it was not possible to provide sufficient heat per se in the air to offset the vaporization of water. However, when small amounts of water vapor were added to the inspirate at high temperatures, bronchospasm was virtually abolished and the response again closely matched theoretical expectations. We conclude that the magnitude of exercise-induced asthma is directly proportional to the thermal load placed on the airways and that this reaction is quantifiable in terms of respiratory heat exchange.

Relationship Between Bronchial Response to Respiratory Heat Exchange and Nonspecific Airways Reactivity in Asthmatic Patients

CHEST Journal ◽  
1984 ◽  
Vol 85 (4) ◽  
pp. 465-470 ◽  
Author(s):  
W.C. Hodgson ◽  
D.J. Cotton ◽  
G.D. Werner ◽  
D.W. Cockcroft ◽  
J. A Dosman
Keyword(s):  
Heat Exchange ◽  
Asthmatic Patients ◽  
Airways Reactivity ◽  
Respiratory Heat Exchange

A Coupled Computational Framework for the Transient Heat Transfer in a Circular Pipe Heated Internally With Expanding Heat Sources

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Chaobin Hu ◽  
Xiaobing Zhang
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Energetic Materials ◽  
Transfer Problem ◽  
Lumped Parameter Model ◽  
Heat Transfer Problem ◽  
Transient Heat Transfer ◽  
Combustion Model ◽  
Heat Sources ◽  
Computational Framework

Abstract In the present work, a transient heat transfer problem induced by internal combustion of energetic materials was studied. Most of previous studies utilized a lumped-parameter model to predict the parameter distributions of the hot combustion products, which determine the boundary conditions for the transient heat transfer problem. Moreover, the heat exchange between the solids and the fluids was ignored in the combustion model. In order to improve the modeling accuracy, a one-dimensional (1D) two-phase flow model was utilized to predict the fluid fields and the heat exchange was coupled into the combustion model. Based on the commercial software abaqus, the transient heat transfer in the combustion chamber was studied using a finite element method. The meshes near the inner surface were refined to capture the high temperature gradients along the radial direction of the barrel. Results indicate that the coupled model is capable of solving the transient heat transfer problems heated by distributed moving heat sources. The coupled computational framework provides foundations for the study of local wear and erosion of solids in extreme working conditions.

Role of respiratory heat exchange in asthma

1984 ◽  
Vol 57 (2) ◽  
pp. 608-609 ◽  
Author(s):  
E. C. Deal ◽  
E. R. McFadden ◽  
R. H. Ingram ◽  
J. J. Jaeger
Keyword(s):  
Heat Exchange ◽  
Respiratory Heat Exchange

A Microcomputer-Based Respiratory Heat Exchange Facility for Use in the Diagnosis of Thermally Induced Asthma

1989 ◽  
Vol 203 (1) ◽  
pp. 43-48 ◽  
Author(s):  
R D Farley ◽  
K R Patel
Keyword(s):  
Heat Exchange ◽  
Heat Loss ◽  
Ambient Air ◽  
Pilot Studies ◽  
Cold Air ◽  
Thermally Induced ◽  
Air Supply ◽  
Lung Dysfunction ◽  
Exercise Induced ◽  
Respiratory Heat Exchange

Exercise-induced asthma is prevalent in many asthmatics and during the winter months can be exacerbated by cold air inhalation. A laboratory facility was required to permit early diagnosis of cold air sensitivity in these patients. This paper describes the development of a modular air conditioning system to produce a range of inhalative thermal burdens and the microcomputer interfacing to measure the rate of airway heat loss imposed. A single-stage refrigerator was built capable of cooling 150 1/min air to —25°C. This was also used to generate dry ambient temperature air by rewarming the chilled air supply. An air humidifier was developed based upon natural convection and evaporation. It was capable of raising 150 1/min ambient air to 37°C, 100 per cent relative humidity. In two pilot studies of 18 asthmatics it was found that the rate of respiratory heat exchange could be correlated with the magnitude of post exertional bronchoconstriction (lung dysfunction) and that exercise-induced asthma could be minimized by attenuating the rate of airway heat loss.

scholarly journals SIMULATION OF HEAT EXCHANGE IN A MULTILAYER FLAT STRUCTURE UNDER PERFECT THERMAL CONTACT IN FIRE CONDITIONS

Fire Safety ◽  
2020 ◽  
Vol 36 ◽  
pp. 115-120
Author(s):  
R. Tatsii ◽  
M. Stasiuk ◽  
O. Pazen
Keyword(s):  
Thermal Conductivity ◽  
Heat Exchange ◽  
Thermal Contact ◽  
Internal Heat ◽  
Nonstationary Temperature ◽  
Heat Sources ◽  
Conductivity Equation ◽  
Flat Structure ◽  
Temperature Changes ◽  
Internal Heat Sources

The proposed work is devoted to the application of the direct method to the study of heat transfer processes in a multilayer flat structure. It is assumed that each layer is made of isotropic material of different thickness. There is an imperfect thermal contact between them, and the layers have internal heat sources. In this case, the isothermal surfaces are parallel planes, i.e the temperature changes in only one direction. On the outer surfaces of the structure there is a convective heat exchange with the environment, i.e the boundary conditions of the third kind are fulfilled. The coefficients of the thermal conductivity equation are considered to be piecewise constant with respect to the spatial coordinate. This is the first time the problem has been solved in this setting. The solution of the problem is realized by applying the method of reduction using the concept of quasi-derivatives and applying the theory of systems of differential equations with impulse action. The following is the procedure for separating Fourier variables using a modified method of eigenfunctions.Based on the physical content of the problem, the differential equation of thermal conductivity was written in the Cartesian coordinate system, but the solution scheme presented here without any fundamental difficulties extends to similar problems for multilayer bodies of basic geometric shapes by switching to appropriate coordinate systems. To illustrate the proposed method, a model example of finding the distribution of a nonstationary temperature field in a seven-layer flat structure under the influence of the hydrocarbon temperature of the fire is solved. The condition of ideal or non-ideal thermal contact is fulfilled between two adjacent layers. In addition, some layers have internal heat sources. The results of the calculations are presented in the form of a graph of temperature changes depending on timeand spatial coordinates.

Based on the Matrix of Silicon Nanocrystals a Modeling Study of Thermo-hydraulic Properties of Micro-channel Heat Transfer Elements

2021 ◽  
Vol 19 (3) ◽  
pp. 38-45
Author(s):  
Forat H. Alsultany ◽  
Qasim S. Kadhim
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Thermal Stabilization ◽  
Specific Power ◽  
Heat Sources ◽  
Ambient Temperatures ◽  
Pressure Losses ◽  
Geometric Configurations ◽  
Wide Range ◽  
The Matrix

The construction of a heat exchange element based on a matrix of silicon whiskers for thermal stabilization systems of miniature heat sources with specific power up to 100 W/cm2 operating over a wide range of ambient temperatures is proposed. Based on the developed mathematical model of convective heat transfer in a microchannel compact heat exchanger with a developed heat exchange surface, numerical simulation of the hydrodynamics and heat transfer processes for various configurations of microchannel insertions was carried out. Fields of pressures, flow velocities, coolant temperatures and matrix from silicon single crystals have been obtained in a wide range of coolant flow rates, criteria dependencies for the Nusselt number and pressure losses of various geometric configurations of heat exchangers have been determined. Critical operation modes are investigated; optimization directions are proposed. According to the developed technology, prototypes for testing have been manufactured.

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