Capillary flow through heat-pipe wicks

1975 ◽  
Author(s):  
J. ENINGER
Keyword(s):  
Heat Pipe ◽  
Capillary Flow ◽  
Flow Through

Vital microscopy of islet blood flow: catecholamine effects in normal and ob/ob mice

1987 ◽  
Vol 252 (1) ◽  
pp. E130-E135 ◽  
Author(s):  
P. Rooth ◽  
I. B. Taljedal
Keyword(s):  
Blood Flow ◽  
Capillary Flow ◽  
Inhibitory Influence ◽  
Video Recordings ◽  
Islet Blood Flow ◽  
Visible Effect ◽  
Flow Through ◽  
Vital Microscopy ◽  
Semiquantitative Method ◽  
Normal Controls

The pancreatic microcirculation in noninbred ob/ob mice and normal controls was visualized in a fluorescence microscope and examined for responses to intravenous infusions of epinephrine or norepinephrine. Evaluations of coded video recordings revealed a smooth dose-response relationship and validated a semiquantitative method of analysis. In ob/ob mice the islet microcirculation was markedly and reversibly inhibited by 0.14–4 micrograms of epinephrine X min-1 X kg body wt-1; the flow was almost totally stopped at the highest infusion rates. Capillary flow in the exocrine pancreas appeared unaffected, except for some inhibition at 4.0 micrograms X min-1 X kg-1. Norepinephrine was less potent an inhibitor of islet blood flow. Normal lean mice exhibited minor responses to 1–11.3 micrograms of epinephrine X min-1 X kg-1; in most cases there was no visible effect. It is concluded that there is a selective regulation of blood flow through the endocrine portion of the pancreas and that the islet microcirculation is hypersensitive to catecholamines in noninbred ob/ob mice. A defective inhibitory influence from the brain may play a role in the development of excessive hyperinsulinemia in ob/ob mice.

Investigation of the capillary flow through open surface microfluidic structures

2017 ◽  
Author(s):  
Ahmed Taher ◽  
Benjamin Jones ◽  
Paolo Fiorini ◽  
Liesbet Lagae
Keyword(s):  
Capillary Flow ◽  
Open Surface ◽  
Flow Through

Vasomotion in chicken foot: dual innervation of arteriovenous anastomoses

1982 ◽  
Vol 242 (5) ◽  
pp. R582-R590 ◽  
Author(s):  
P. E. Hillman ◽  
N. R. Scott ◽  
A. van Tienhoven
Keyword(s):  
Capillary Flow ◽  
Arteriovenous Anastomoses ◽  
Adrenergic Agonists ◽  
Beta Adrenergic ◽  
Beta Adrenergic Agonists ◽  
Collateral Vein ◽  
Flow Through ◽  
Purinergic Nerves ◽  
Counter Current ◽  
Stimulation Of

Blood exits the foot of the domestic chicken via two major venous routes: a counter-current network surrounding the major incoming artery and a large collateral vein. Between these two routes are numerous large collateral vein. Between these two routes are numerous anastomotic veins. Both venous routes drain capillaries and arteriovenous anastomoses (AVAs). Blood flow through the foot was measured on unanesthetized hens. Flow varies with ambient temperature: 0.2 ml/min at 5 degrees C, 2.2 ml/min at thermoneutrality, and 5.4 ml/min at 36 degrees C; the AVAs contribute 8, 26, and 63% to this flow, respectively. Flow through capillaries is reduced by alpha-adrenergic agonists and is increased by beta-adrenergic agonists. Blocking nerve conduction to the foot at thermoneutrality releases alpha-adrenergic tone and increase AVA flow. Faradic stimulation of foot nerves after adrenergic blockage increases AVA flow, but not capillary flow, suggesting active vasodilation of the AVAs. Such AVA vasodilation normally occurs during body heating, since AVA flow decreases after denervation. Dopaminergic or beta-adrenergic nerves are not involved in active vasodilatation, however, purinergic nerves may play a role. Thus AVAs have a functional dual innervation.

Thermal and Fluid Dynamic Model for Capillary-Driven Heat Pipe With Closed-Form Solution

2017 ◽  
Author(s):  
Jesse Maxwell
Keyword(s):  
Boundary Condition ◽  
Heat Flux ◽  
Closed Form ◽  
Heat Pipe ◽  
Closed Form Solution ◽  
Constant Heat Flux ◽  
Form Solution ◽  
Constant Heat ◽  
Micro Channels ◽  
Flow Through

A model is derived for the steady state performance of capillary-driven heat pipes on the basis treating fluid flow through miniature- and micro-channels and applied as bulk properties to a large aspect ratio quasi-one-dimensional two-phase system. Surface tension provides the driving force based on an equivalent bulk capillary radius while laminar flow through micro-channels and the vapor core are treated. Heat conduction is accounted for radially while isothermal advection is treated along the axis. A closed-form solution is derived for a steady state heat pipe with a constant heat flux boundary condition on the evaporator as well as a constant heat flux or a convective boundary condition along the condenser. Two solution methods are proposed, and the result is compared to empirical data for a copper-water heat pipe. The components of the closed-form solution are discussed as contributors to driving or frictional forces, and the existence of an optimal pore radius is demonstrated.

A fractal model for capillary flow through a single tortuous capillary with roughened surfaces in fibrous porous media

Fractals ◽  
2020 ◽  
Author(s):  
Boqi Xiao ◽  
Qiwen Huang ◽  
Yan Wang ◽  
Hanxin Chen ◽  
Xubing Chen ◽  
...  
Keyword(s):  
Porous Media ◽  
Capillary Flow ◽  
Fractal Model ◽  
Fibrous Porous Media ◽  
Flow Through

Electroosmotic Flow Through Porous Materials

2014 ◽  
Author(s):  
Rakesh Saini ◽  
Matthew Kenny ◽  
Dominik P. J. Barz
Keyword(s):  
Porous Materials ◽  
Electroosmotic Flow ◽  
Capillary Flow ◽  
Cost Effective ◽  
Packed Bed ◽  
Flow Rates ◽  
Bed Porosity ◽  
Flow Through ◽  
Set Up ◽  
Air Liquid Interface

Electroosmotic flow can be employed in many microfluidic systems. Especially, highly porous materials are suitable since they generate significant flow rates and pressures. In the current research, we employ electroosmosis experiments using a relatively simple and cost-effective set-up including different sets of sintered packed beds of borosilicate micro spheres having a wider range of porosities. Various experiments are performed with varying applied electric field, and packed bed porosity. The flow rates are measured by tracking the air/liquid interface in a capillary which is connected to the packed bed. A mathematical model of the setup reveals the influence of the capillary flow on the flow rate of the electroosmotic flow.

Comparison of Heat Transfer in Solar Collectors With Heat-Pipe Versus Flow-Through Absorbers

1987 ◽  
Vol 109 (4) ◽  
pp. 253-258 ◽  
Author(s):  
J. R. Hull
Keyword(s):  
Heat Transfer ◽  
Heat Pipe ◽  
Solar Collector ◽  
Hot Water ◽  
Solar Collectors ◽  
Heat Transfer Characteristics ◽  
Absorption Chiller ◽  
Transfer Characteristics ◽  
Proper Design ◽  
Flow Through

Analysis of heat transfer in solar collectors with heat-pipe absorbers is compared to that for collectors with flow-through absorbers for systems that produce hot water or other heated fluids. In these applications the heat-pipe absorber suffers a heat transfer penalty compared with the flow-through absorber, but in many cases the penalty can be minimized by proper design at the heat-pipe condenser and system manifold. When the solar collector is used to drive an absorption chiller, the heat-pipe absorber has better heat transfer characteristics than the flow-through absorber.

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