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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 73 records · Page 4

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NASA NTRS1995

Pharmacologic Atrial Natriuretic Peptide Reduces Human Leg Capillary Filtration

Atrial natriuretic peptide (ANP) is produced and secreted by atrial cells. We measured calf capillary filtration rate with prolonged venous-occlusion plethysmography of supine healthy male subjects during pharmacologic infusion of ANP (48 pmol/kg/min for 15 min; n = 6) and during placebo infusion (n = 7). Results during infusions were compared to prior control measurements. ANP infusion increased plasma (ANP) from 30 +/- 4 to 2,568 +/- 595 pmol/L. Systemic hemoconcentration occurred during ANP infusion: mean hematocrit and plasma colloid osmotic pressure increased 4.6 and 11.3%, respectively, relative to preinfusion baseline values (p less than 0.05). Mean calf filtration, however, was significantly reduced from 0.15 to 0.08 ml/100 ml/min with ANP. Heart rate increased 20% with ANP infusion, whereas blood pressure was unchanged. Calf conductance (blood flow/ arterial pressure) and venous compliance were unaffected by ANP infusion. Placebo infusion had no effect relative to prior baseline control measurements. Although ANP induced systemic capillary filtration, in the calf, filtration was reduced with ANP. Therefore, pharmacologic ANP infusion enhances capillary filtration from the systemic circulation, perhaps at upper body or splanchnic sites or both, while having the opposite effect in the leg.

Watenpaugh, Donald E.↗

NASA NTRS1995

Pharmacologic Atrial Natriuretic Peptide Reduces Human Leg Capillary Filtration

Atrial natriuretic peptide (ANP) is produced and secreted by atrial cells. We measured calf capillary filtration rate with prolonged venous-occlusion plethys-mography of supine health male subjects during pharmacologic infusion of ANP (48 pmol/kg/min for 15 min; n equals 6) and during placebo infusion (n equals 7). Results during infusions were compared to prior control measurements. ANP infusion increased plasma (ANP) from 30 plus or minus 4 to 2,568 plus or minus 595 pmol/L. Systemic hemoconcentration occurred during ANP infusion; mean hematocrit and plasma colloid osmotic pressure increased 4.6 and 11.3 percent respectively, relative to pre-infusion baseline values (p is less than 0.05). Mean calf filtration, however was significantly reduced from 0.15 to 0.08 ml/100 ml/min with ANP. Heart rate increased 20 percent with ANP infusion, wheras blood pressure was unchanged. Calf conductance (blood flow/arterial pressure) and venous compliance were unaffected by ANP infusion. Placebo infusion had no effect relative to prior baseline control measurements. Although ANP induced systemic capillary filtration, in the calf, filtration was reduced with ANP. Therefore, phamacologic ANP infusion enhances capillary filtration from the systemic circulation, perhaps at upper body or splanchic sites or both, while having the opposite effect in the leg.

Watenpaugh, Donald E.↗

NASA NTRS1994

Capillary Movement of Liquid in Granular Beds in Microgravity

A more complete understanding of the dynamics of capillary flow through an g unsaturated porous medium would be useful for a number of space and terrestrial applications. One such application involves the development of an effective water and nutrient delivery system for the growth of plants in space. An experiment was conducted on the Mir Space Station that used an experimental cuvette called "Capillary Test Bed". An objective of this experiment was to compare fluid migration in the "Capillary Test Bed" under terrestrial laboratory simulated microgravity conditions by positioning the cuvette such that the hydrostatic force is negated and on Mir at microgravity conditions. Difference in fluid migration in the cuvette were observed. Based on these observations, improvements in the design of the cuvette are under-way that should allow for collection of more precise data in future flight experiments. The results of the MIR experiment and modifications being made to the cuvette for improved data collection will be discussed.

Yendeler, Boris S.↗

NASA NTRS2001

Use of Capillaries for Macromolecular Crystallization in a Cryogenic Dewar

The Enhanced Gaseous Nitrogen (EGN) Dewar is a cryogenic dry shipper with a sealed cylinder inserted inside along with a temperature-monitoring device, and is intended for macromolecular crystallization experiments on the International Space Station. Within the Dewar, each crystallization experiment is contained as a solution within a plastic capillary. The standard procedure for loading samples in these tubes has involved rapid freezing of the precipitant and biomolecule solution directly in liquid nitrogen; this method, however, often results in uncontrolled formation of air voids. These air pockets, or bubbles, then can lead to irreproducible crystallization results. A novel protocol has been developed to prevent formation of bubbles, and this has been tested in the laboratory as well as aboard the International Space Station during a 42-day long mission of July/August of 2001. Furthermore, gain or loss of mass from solutions within the capillaries revealed that mass transport amongst separated tubes occurred, and that this mass transport was determined by the hygroscopic character of a solution contained in any given tube. The sample volume and the surface area of the plastic capillary tube also related to the observed mass transport.

Ciszak, Ewa↗

NASA NTRS2002

Use of Capillaries for Macromolecular Crystallization in a Cryogenic Dewar

The enhanced gaseous nitrogen (EGN) dewar is a cryogenic dry shipper with a sealed cylinder inserted inside along with a temperature monitoring device, and is intended for macromolecular crystallization experiments on the International Space Station. Within the dewar, each crystallization experiment is contained as a solution within a plastic capillary tube. The standard procedure for loading samples in these tubes has involved rapid freezing of the precipitant and biomolecular solution, e.g., protein, directly in liquid nitrogen; this method, however, often resulted in uncontrolled formation of air voids, These air pockets, or bubbles, can lead to irreproducible crystallization results. A novel protocol has been developed to prevent formation of bubbles, and this has been tested in the laboratory as well as aboard the International Space Station during a 42-day long mission of July/August 2001. The gain or loss of mass from solutions within the plastic capillaries revealed that mass transport occurred among separated tubes, and that this mass transport was dependent upon the hygroscopic character of the solution contained in any given tube. The surface area of the plastic capillary tube also related to the observed mass transport. Furthermore, the decreased mass of solutions of-protein correlated to observed formation of protein crystals.

Ciszak, Ewa↗

NASA NTRS2002

Flight Testing of the Capillary Pumped Loop 3 Experiment

The Capillary Pumped Loop 3 (CAPL 3) experiment was a multiple evaporator capillary pumped loop experiment that flew in the Space Shuttle payload bay in December 2001 (STS-108). The main objective of CAPL 3 was to demonstrate in micro-gravity a multiple evaporator capillary pumped loop system, capable of reliable start-up, reliable continuous operation, and heat load sharing, with hardware for a deployable radiator. Tests performed on orbit included start-ups, power cycles, low power tests (100 W total), high power tests (up to 1447 W total), heat load sharing, variable/fixed conductance transition tests, and saturation temperature change tests. The majority of the tests were completed successfully, although the experiment did exhibit an unexpected sensitivity to shuttle maneuvers. This paper describes the experiment, the tests performed during the mission, and the test results.

Ottenstein, Laura↗

NASA NTRS2004

Enhanced Damping for Capillary Bridge Oscillation Using Velocity Feedback

The stability of cylindrical liquid bridges in reduced gravity is affected by ambient vibrations of the spacecraft. Such vibrations are expected to excite capillary modes of the bridge. The lowest-order unstable mode is particularly susceptible to vibration as the length of the bridge approaches the stability limit. This low-order mode is known as the (2,0) mode and is an axisymmetric varicose mode of one wavelength in the axial direction. In this work, an optical system is used to detect the (2,0)-mode amplitude. The derivative of the error signal produced by this detector is used to produce the appropriate voltages on a pair of ring electrodes which are concentric with the bridge. A mode-coupled Maxwell stress profile is thus generated in proportional to the modal velocity. Depending on the sign of the gain, the damping of the capillary oscillation can be either increased or decreased. This effect has been demonstrated in Plateau-tank experiments. Increasing the damping of the capillary modes on free liquid surfaces in space could be beneficial for containerless processing and other novel technologies. [work supported by NASA]

Wei, Wei↗

NASA NTRS2004

Enhanced Damping for Capillary Bridge Oscillation Using Velocity Feedback

Wei, Wei↗

NASA NTRS2005

Heat Load Sharing in a Capillary Pumped Loop with Multiple Evaporators and Multiple Condensers

This paper describes the heat load sharing function among multiple parallel evaporators in a capillary pumped loop (CPL). In the normal mode of operation, the evaporators cool the instruments by absorbing the waste heat. When an instruments is turned off, the attached evaporator can keep it warm by receiving heat from other evaporators serving the operating instruments. This is referred to as heat load sharing. A theoretical basis of heat load sharing is given first. The fact that the wicks in the powered evaporators will develop capillary pressure to force the generated vapor to flow to cold locations where the pressure is lower leads to the conclusion that heat load sharing is an inherent function of a CPL with multiple evaporators. Heat load sharing has been verified with many CPLs in ground tests. Experimental results of the Capillary Pumped Loop 3 (CAPL 3) Flight Experiment are presented in this paper. Factors that affect the amount of heat being shared are discussed. Some constraints of heat load sharing are also addressed.

Ku, Jentung↗

NASA NTRS2005

Capillary-Driven Flow in Liquid Filaments Connecting Orthogonal Channels

Capillary phenomena plays an important role in the management of product water in PEM fuel cells because of the length scales associated with the porous layers and the gas flow channels. The distribution of liquid water within the network of gas flow channels can be dramatically altered by capillary flow. We experimentally demonstrate the rapid movement of significant volumes of liquid via capillarity through thin liquid films which connect orthogonal channels. The microfluidic experiments discussed provide a good benchmark against which the proper modeling of capillarity by computational models may be tested. The effect of surface wettability, as expressed through the contact angle, on capillary flow will also be discussed.

Allen, Jeffrey S.↗

NASA NTRS2005

Capillary Flow Experiments Began on the International Space Station

The Capillary Flow Experiments (CFEs) are a suite of fluid physics flight experiments designed to investigate capillary flows and phenomena in low gravity. Data obtained from the CFEs will be crucial to NASA s Space Exploration Initiative, particularly pertaining to fluids management systems such as fuels and cryogen storage systems, thermal control systems (e.g., water recycling), and materials processing in the liquid state. NASA s current plans for exploration missions assume the use of larger liquid propellant masses than have ever flown on interplanetary missions. Under low-gravity conditions, capillary forces can be exploited to control fluid orientation so that such large mission-critical systems perform predictably. The first of the CFE experiments has been conducted on the International Space Station, and the data are being analyzed. The experiment suite is described briefly.

J. Mark Hickman↗

NASA NTRS2006

Capillary Limit of a Miniature Loop Heat Pipe with Multiple Evaporators and Multiple Condensers

An experimental investigation of a miniature loop heat pipe with multiple evaporators and multiple condensers were conducted in order to evaluate its capillary limit. The experimental tests were conducted by varying heat load to one or both evaporators, with and without active temperature control of compensation chamber (CC) using the thermoelectric devices, and variable tilts between the evaporators and the CCs. The physical process of the loop and thermal conductance of the heat leak from evaporator to (CC) were discussed based on the test results. The difference of the temperature profiles between with and without active control of CC temperature was evaluated. The effect of the gravity on capillary limit and CC temperature was also evaluated by comparing the test result in horizontal position with that in vertical position. The loop recovery after capillary limit was exceeded was also described.

Ku, Jentung↗

NASA NTRS2010

Capillary condenser/evaporator

A heat transfer device is disclosed for transferring heat to or from a fluid that is undergoing a phase change. The heat transfer device includes a liquid-vapor manifold in fluid communication with a capillary structure thermally connected to a heat transfer interface, all of which are disposed in a housing to contain the vapor. The liquid-vapor manifold transports liquid in a first direction and conducts vapor in a second, opposite direction. The manifold provides a distributed supply of fluid (vapor or liquid) over the surface of the capillary structure. In one embodiment, the manifold has a fractal structure including one or more layers, each layer having one or more conduits for transporting liquid and one or more openings for conducting vapor. Adjacent layers have an increasing number of openings with decreasing area, and an increasing number of conduits with decreasing cross-sectional area, moving in a direction toward the capillary structure.

Valenzuela, Javier A.↗

NASA NTRS2015

Regolith and Environment Science and Oxygen and Lunar Volatile Extraction (RESOLVE): Lunar Advanced Volatile Analysis (LAVA) Capillary Fluid Dynamic Restriction Effects on Gas Chromatography

The Resource Prospector (RP) mission with the Regolith and Environment Science and Oxygen Lunar Volatile Extraction (RESOLVE) payload aims to show the presence of water in lunar regolith, and establish a proving ground for NASAs mission to Mars. One of the analysis is performed by the Lunar Advanced Volatiles Analysis (LAVA) subsystem, which consists of a fluid network that facilitates the transport of volatile samples to a gas chromatograph and mass spectrometer (GC-MS) instrument. The understanding of fluid dynamics directed from the GC to the MS is important due to the influence of flow rates and pressures that affect the accuracy of and prevent the damage to the overall GC-MS instrument. The micro-scale capillary fluid network within the GC alone has various lengths and inner-diameters; therefore, determination of pressure differentials and flow rates are difficult to model computationally, with additional complexity from the vacuum conditions in space and lack of a lunar atmosphere. A series of tests were performed on an experimental set-up of the system where the inner diameters of the GC transfer line connecting to the MS were varied. The effect on chromatography readings were also studied by applying these lines onto a GC instrument. It was found that a smaller inner diameter transfer line resulted in a lower flow rate, as well as a lower pressure differential across the thermal conductivity detector (TCD) unit of the GC and a negligible pressure drop across the mock-up capillary column. The chromatography was affected with longer retention times and broader peak integrations. It was concluded that a 0.050 mm inner diameter line still proved most suitable for the systems flow rate preferences. In addition, it was evident that this small transfer line portrayed some expense to GC signal characteristics and the wait time for steady-state operation.

RESOLVE↗

DOE OSTI2024

Capillary-Enhanced Two-Phase Micro-Cooler Using Copper-Inverse-Opal Wick with Silicon Microchannel Manifold for High-Heat-Flux Cooling Application

In this work, we demonstrate a two-phase capillary-fed boiling micro-cooler that consists of a ~ 25-..mu..m-thick copper inverse opal (CIO) porous wicking structure for high-heat-flux boiling and a silicon 3D-manifold for distributed liquid delivery and vapor extraction across a 0.5 cm x 0.5 cm heated area. At low inlet water mass flow rates of 1.5 to 1.9 g(min)-1, the micro-cooler displays nearly two-phase boiling with exit vapor quality ~ 1 and a high critical heat flux (CHF) of 253 to 320 W cm-2 with low superheat of ~ 10 degrees C resulting in a thermal resistance of boiling ~ 0.025 cm2 degrees C W-1 or heat transfer coefficient of 0.4 MW m-2 degrees C-1. For higher flow rates of 5, 10, and 15 g(min)-1, the micro-cooler exhibits a hybrid single-phase and two-phase cooling regime where the contribution of the sensible heat (single-phase) cooling is linearly added to that of the two-phase cooling. For the highest flow rate of 15 g(min)-1, the CHF is increased to ~ 500 W cm-2 resulting in an overall thermal resistance of ~ 0.18 cm2 degrees C W-1. However, the two-phase heat transfer effectiveness, which estimates the utilization level of the inlet mass flow rate for two-phase boiling, is reduced to ~ 0.11. To achieve the best cooling system performances, the micro-cooler must operate entirely within the two-phase boiling regime (exit vapor quality or two-phase heat transfer effectiveness ~ 1). Ideally, the "coolant" should be delivered near its saturation temperature (~ 100 degrees C for water), which provides significant advantages for the energy-efficient operation of data centers and power electronics. We present detailed analysis with Infrared and high speed camera images at various inlet flow rates and heat fluxes to understand complex heat transfer in the micro-cooler. Furthermore, a conjugate thermofluidic simulation model, which incorporates the physics of capillary-fed boiling in a porous copper layer, agrees well with the experimental data.

capillary-enhanced boiling↗

NASA NTRS1995

A Simple Theory of Capillary-Gravity Wave Turbulence

An analytical solution is presented for deriving inertial spectra of capillary-gravity waves. The theory successfully explains dependence of the wave spectrum on wind input and describes the accelerated roll-off of the spectral density function in the narrow sub-range separating scale-invariant regimes of purely gravity and capillary waves.

multi-wave↗

NASA NTRS1972

Internal capillary insulation for cryogenic tanks

Capillary-type insulation was devised for installation on inside of liquid methane fuel tanks for future aircraft. Insulation consists of honeycomb core of fiberglass cloth impregnated with polyimide resin which is bonded onto metal tank wall using polyimide adhesive. Capillary holes in each honeycomb cell admit methane which provides static pressure in cell.

Mcgrew, J. L.↗

NASA NTRS1975

Capillary flow through heat-pipe wicks

Theoretical expressions are obtained for the capillary-pressure limit and permeability of a fibrous wick in terms of the porosity and fiber diameter. Hysteresis in capillary pressure is included through the introduction of an empirical hysteresis constant. A partial-saturation model based on the statistical distribution of local porosity requires an additional empirical constant, the standard deviation. The theory is compared to results of a beta-ray absorption experiment that measured the liquid content of a partially saturated wick and to results of permeability measurements on partially and fully saturated wicks. A simple wick-weighing experiment is described that yields values for the empirical hysteresis constant and the standard deviation. Theoretical results are used to design an optimum wick.

Eninger, J. E.↗