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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 631 records · Page 35
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NASA NTRS1972

Thermal conductivity of filled RTV compounds

Sealant materials with high thermal conductivity, and electrically nonconductive were studied for applications. Alumina and other thermally conductive fillers were examined for room temperature vulcanizing (RTV) use. The guarded hot plate apparatus, and its operation are described, and results of the thermal conductivity tests are discussed. It was found that magnesium oxide is significantly better than aluminum oxide as a filler enhancing the thermal conductivity of RTV. Recommendations for future studies are included.

Mauk, C. E.↗
NASA NTRS1972

Pattern of filling in the pulmonary capillary bed.

Artificially ventilated and perfused dog lungs were rapidly frozen under various physiological conditions. In 2-micron-thick sections the number of red blood cells (RBCs) per 10-micron length of alveolar septum was counted. Under conditions in which alveolar pressure exceeded venous pressure, variation in RBC concentration within areas supplied by single arterioles accounted completely for variation between areas supplied by different arterioles. Except at very high perfusion pressures when venous pressure exceeded alveolar pressure, there was no significant correlation between RBC concentrations of pairs of adjacent septa.

Warrell, D. A.↗
NASA NTRS1972

Effect of stratified inequality of blood flow on gas exchange in liquid-filled lungs.

This investigation set out to answer two questions: (1) are the distal alveoli in the terminal lung units less well perfused than the proximal alveoli, i.e., is there stratification of blood flow; and (2) if so, does this enhance gas exchange in the presence of stratified inequality of ventilation. Excised dog lungs were ventilated with saline and perfused with blood. Following single inspirations of xenon 133 in saline and various periods of breath holding, the expired xenon concentration against volume was measured and it confirmed marked stratified inequality of ventilation under these conditions. By measuring the rate of depletion of xenon from alveoli during a period of blood flow, we showed that the alveoli which emptied at the end of expiration had 16% less blood flow than those exhaling earlier. However, by measuring the xenon concentration in pulmonary venous blood, we found that about 10% less tracer was transferred from the alveoli into the blood when the inspired xenon was stratified within the respiratory zone. Thus while stratification of blood flow was confirmed, it was shown to impair rather than enhance the efficiency of gas transfer.

West, J. B.↗
NASA NTRS1973

Dynamics of moisture diffusion through a partially liquid filled porous matrix.

Models for unsteady water transport in fuel cell configurations of Bacon-Pratt and Whitney type are derived. Tests with a specially constructed isothermal cell producing no water and order of magnitude analysis show that diffusion through the liquid alone cannot account for the observed behavior. An analytical solution which includes diffusion in both the liquid and the gas spaces of the matrix is in better agreement with the data than models which consider diffusion in either the liquid or in the gas phase alone.

Murty, B. G. K.↗