Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “HEAT FLOW”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

The effects of orbital and climatic variations on Martian surface heat flow

We have examined the effects of climate changes, induced by orbital oscillations, on Martian surface heat flow. It was found that the climatological component of the surface heat flow can be larger than the expected internal geothermal heat flow. We suggest that measurements of surface heat flow be targeted for equatorial and south polar regions to avoid climatic effects and that care be taken in interpreting measurements in mid-latitude and north polar regions.

Mellon, Michael T.↗
NASA NTRS1985

Heat flow and continental breakup: The Gulf of Elat (Aqaba)

Heat flow measurements were made in the major basins of the Gulf of Elat (Aqaba), northern Red Sea. The gulf is located at the southern portion of the Dead Sea rift which is a transform plate boundary. Gradient measurements at each site were made with a probe which allows multiple penetration of the bottom during a single deployment of the instrument. Thermal conductivity was determined by needle probe measurements on sedimentary cores. The mean heat flux, about 80 mWm(-2), is significantly above the continental mean, and probably also above that from the adjacent Sinai and Arabian continental blocks. The heat flow appears to increase from north to south. Such an increase may be related to the more advanced rifting stage of the Red Sea immediately to the south, which presently includes creation of an oceanic crust. This trend also corresponds to the general trend of the deep crustal structure in the gulf. Evidence from various geophysical fields suggest a gradual thinning of the crust towards the direction of the Red Sea where a normal oceanic crust exists. The heat flow data, together with other geophysical data, indicate a propagation of mature rifting activity from the Red Sea into the Gulf of Elat. This process is acting simultaneously with the transform motion along the Dead Sea rift.

Ben-Avraham, Z.↗
NASA NTRS1985

Heat flow in eastern Egypt - The thermal signature of a continental breakup

Data on the heat flow in eastern Egypt were collected to provide information related to the mode and the mechanism of the Red Sea opening. The data indicate a general increase in heat flow towards the Red Sea (75-100 mW/sq m in a zone within 40 km of the coast compared with 35-55 mW/sq m inland). Moderately high heat flow (about 70 mW/sq m) was found for the Gulf of Suez. Heat production data indicate that the coastal thermal anomaly is not primarily related to crustal radiogenic heat production. Possible causes of the anomaly (one of which could be a high mantle heat flow causing a lithospheric thinning centered beneath the Red Sea) are discussed.

Morgan, P.↗
NASA NTRS1994

Io's heat flow from infrared radiometry: 1983-1993

We report the following results from a decade of infrared radiometry of Io: (1) The average global heat flow is more than approx. 2.5 W/sq.m, (2) large warm (less than or equal to 200 K) volcanic regions dominate the global heat flow, (3) smal high-temperature (greater than or = 300 K) 'hotspots' contribute little to the average heat flow, (4) thermal anomalies on the leading hemisphere contribute about half of the heat flow, (5) a substantial amount of heat is radiated during Io's night, (6) high-temperature (greater than or = 600 K) 'outbursts' occurred during approx. 4% of the nights we observed, (7) 'Loki' is the brightest, persistent, infrared emission feature, and (8) some excess emission is always present at the longitude of Loki, but its intensity and other characteristics change between apparitions. Observations of Io at M(4.8 micrometer), 8.7 micrometer, N(10 micrometer), and Q(20 micrometer) with the Infrared Telescope Facility presented here were collected during nine apparitions between 1983 and 1993. These measurements provide full longitudinal coveraged as well as an eclipse observation and the detection of two outbursts. Reflected sunlight, passive thermal emission, and radiation from thermal anomalies all contribute to the observed flux densities. We find that a new thermophysical model is required to match all the data. Two key elements of this model are (1) a 'thermal reservoir' unit which lowers daytime temperatures, and (2) the 'thermal pedestal effect' which shifts to shorter wavelengths the spectral emission due to the reradiation of solar energy absorbed by the thermal anomalies. The thermal anomalies are modeled with a total of 10 source components at five locations. Io's heat flow is the sum of the power from these components.

Veeder, Glenn J.↗
NASA NTRS1972

Development of an in situ thermal conductivity measurement for the lunar heat flow experiment.

Discussion of the design and calibration of the heat flow experiment of the Apollo Lunar Scientific Experiments Package (ALSEP). The principal objective is to gain evidence on the bulk chemistry of the moon. The heat flow is determined by making independent measurements of the vertical temperature gradient and the thermal conductivity in the inner surface layer (the regolith). Attention is given to the errors associated with the experimental technique. The low thermal conductivity of the regolith layer presents both advantages and disadvantages in heat flow measurement.

Langseth, M. G., Jr.↗
NASA NTRSDate not supplied

Influence of Heat Flow from the Planetary Interior on Surface Habitability

an primordial and/or radiogenic heat flow from a rocky planet’s interior help maintain a surface environment amenable to life?On rocky Earth-like planets with shallow oceans (≤5 km depth) that are on the outer edge of the habitable zone, the additional energy provided might make the difference between a world supporting regional habitat space and a world uninhabitable by any known life-form. To test this hypothesis, we introduce heat flux from the planetary interior as a forcing to the NASA/GISSROCKE-3D exoplanet GCM, and explore whether it can enhance the habitability of marginal terrestrial rocky planets (e.g.,paleo Earth in a “snowball” climate state).GCM simulations of modern Earth have not included geothermal heat flux as a climate forcing, as it is more than an order of magnitude less than the 2.9 W/m heating caused by anthropogenic greenhouse gases [Flanner, GRL 2009]. Modern Earth measurements in the oceans [Downes et al., GRL 2019] and results from ocean GCMs [Barnes et al., Ocean Model. 2017]suggest that localized higher heat flux can have measurable thermodynamic and dynamic impacts, such as weakening deep ocean stratification and increased poleward ocean heat transports. A similar result with ROCKE-3D would be important, since our snowball Earth simulations without heat flux produce features like ocean stratification that should have hampered the survival of life. We have created a set of spatially variable geothermal heat fluxes at varying horizontal resolutions based on modern Earth heat flow patterns [Davies, Geochem. Geophys. Geosys. 2013] to test the sensitivity of the ROCKE-3D GCM initially in a modern Earth context. Preliminary results show that even modest heat fluxes have a measurable impact on deep ocean temperatures (upto +0.9°C locally) and that this heat can be transported at depth along ocean circulation paths. Estimates of heat flux impacts on vertical ocean mixing and surface ocean conditions require long simulations at the higher spatial resolutions needed to express heat flow at the scale of most ocean ridges. Ongoing simulations are focused on testing the impacts of horizontal resolution and flux scaling on surface environments, especially for “snowball” climate scenarios.

Heat flow↗
NASA NTRS1993

Constraints on lithospheric thermal structure for the Indian Ocean from depth and heat flow data

Models for the thermal evolution of oceanic lithosphere are primarily constrained by variations in seafloor depth and heat flow with age. These models have been largely based on data from the Pacific and Atlantic Ocean basins. We construct seafloor age relations for the Indian Ocean which we combine with bathymetric, sediment isopach and heat flow data to derive curves for depth and heat flow versus age. Comparison of these curves with predictions from three thermal models shows that they are better fit by the shallower depths and higher heat flow for the GDH1 model, which is characterized by a thinner and hotter lithosphere than previous models.

Shoberg, Tom↗
NASA NTRS2012

James Webb Space Telescope Integrated Science Instrument Module Calibration and Verification of High-Accuracy Instrumentation to Measure Heat Flow in Cryogenic Testing

The James Webb Space Telescope (JWST) is an upcoming flagship observatory mission scheduled to be launched in 2018. Three of the four science instruments are passively cooled to their operational temperature range of 36K to 40K, and the fourth instrument is actively cooled to its operational temperature of approximately 6K. The requirement for multiple thermal zoned results in the instruments being thermally connected to five external radiators via individual high purity aluminum heat straps. Thermal-vacuum and thermal balance testing of the flight instruments at the Integrated Science Instrument Module (ISIM) element level will take place within a newly constructed shroud cooled by gaseous helium inside Goddard Space Flight Center's (GSFC) Space environment Simulator (SES). The flight external radiators are not available during ISIM-level thermal vacuum/thermal testing, so they will be replaced in test with stable and adjustable thermal boundaries with identical physical interfaces to the flight radiators. Those boundaries are provided by specially designed test hardware which also measures the heat flow within each of the five heat straps to an accuracy of less than 2 mW, which is less than 5% of the minimum predicted heat flow values. Measurement of the heat loads to this accuracy is essential to ISIM thermal model correlation, since thermal models are more accurately correlated when temperature data is supplemented by accurate knowledge of heat flows. It also provides direct verification by test of several high-level thermal requirements. Devices that measure heat flow in this manner have historically been referred to a "Q-meters". Perhaps the most important feature of the design of the JWST Q-meters is that it does not depend on the absolute accuracy of its temperature sensors, but rather on knowledge of precise heater power required to maintain a constant temperature difference between sensors on two stages, for which a table is empirically developed during a calibration campaign in a small chamber at GSFC. This paper provides a brief review of Q-meter design, and discusses the Q-meter calibration procedure including calibration chamber modifications and accommodations, handling of differing conditions between calibration and usage, the calibration process itself, and the results of the tests used to determine if the calibration is successful.

Comber, Brian↗
NASA NTRS1974

Heat flow and geothermal potential of the East Mesa KGRA, Imperial Valley, California

The East Mesa KGRA (Known Geothermal Resource Area) is located in the southeast part of the Imperial Valley, California, and is roughly 150 kilometers square in areal extent. A new heat flow technique which utilizes temperature gradient measurements across best clays is presented and shown to be as accurate as conventional methods for the present study area. Utilizing the best clay gradient technique, over 70 heat flow determinations have been completed within and around the East Mesa KGRA. Background heat flow values range from 1.4 to 2.4 hfu (1 hfu = .000001 cal. per square centimeter-second) and are typical of those throughout the Basin and Range province. Heat flow values for the northwest lobe of the KGRA (Mesa anomaly) are as high as 7.9 hfu, with the highest values located near gravity and seismic noise maxima and electrical resistivity minima. An excellent correlation exists between heat flow contours and faults defined by remote sensing and microearthquake monitoring.

Swanberg, C. A.↗
NASA NTRS2012

James Webb Space Telescope Integrated Science Instrument Module Calibration and Verification of High-Accuracy Instrumentation to Measure Heat Flow in Cryogenic Testing

The James Webb Space Telescope (JWST) is an upcoming flagship observatory mission scheduled to be launched in 2018, Three of the four science instruments are passively cooled to their operational temperature range of 36K to 40K, and the fourth instrument is actively cooled to its operational temperature of approximately 6K. The requirement for multiple thermal zones results in the instruments being thermally connected to five external radiators via individual high purity aluminum heat straps. Thermal-vacuum and thermal balance testing of the flight instruments at the Integrated Science Instrument Module (ISIM) element level will take place within a newly constructed shroud cooled by gaseous helium inside Goddard Space Flight Center's (GSFC) Space Environment Simulator (SES). The flight external radiators are not available during ISIM-Ievel thermal vacuum/thermal testing, so they will be replaced in test with stable and adjustable thermal boundaries with identical physical interfaces to the flight radiators. Those boundaries are provided on specially designed test hardware which measures the heat flow within each of the five heat straps to an accuracy of less than 2 m W, which is less than 5% of the minimum predicted heat flow values. This is essential to ISIM thermal model correlation, since thermal models are more accurately correlated when temperature data is supplemented by accurate knowledge of heat flows. Devices that measure heat flow in this manner have historically been referred to as "Q-meters". Perhaps the most important feature of the design of the Q-meters is that it does not depend on the absolute accuracy of its temperature sensors, but rather on a difference in heater power, for which a table is empirically developed during a calibration campaign in a small chamber at GSFC. This paper discusses the Q-meter calibration procedure including calibration chamber modifications and accommodations, the handling of differing conditions between calibration and usage, the calibration process itself, and the results of the tests used to determine if the calibration is successful.

Comber, Brian↗
NASA NTRS1983

Minimal upper mantle temperature variations consistent with observed heat flow and plate velocities

Heat-flow and plate-velocity measurements are used to model upper-mantle temperature variations; the results are intended to form the basis for a gravity-field-variation model and are also applicable to the interpretation of petrological and seismological data. A 5-deg grid is used, a depth of 280 km is chosen as the fully convecting level, and it is assumed that 85 percent of the global heat production (4.0 x 10 to the 13th W) comes from below this level. The velocity field is calculated by integrating the momentum equations down to 280 km (assuming laterally homogeneous viscosity and density) and then used to determine the temperature fields. The results are presented in graphs, tables, and maps. The largest lateral temperature differences are about 1500 C and occur in the top 20 km, where the largest (about 200 C/Myr) nonlinear terms of the energy equation are also found. Below 50 km, heat transfer becomes more convective than conductive, and the most significant temperature variation appears in the form of negative 'tongues' as cold as -825 C at about 100 km. Temperature variations of at least + or - 180 C are calculated at the fully convecting level.

Kaula, W. M.↗
NASA NTRS1981

Heat flow from Io /JI/

The existing ground-based measurements of Io's thermal emission at infrared wavelengths of 8.4, 10.6, and 21 microns have been reexamined. Present in these data is the signature of hot spots, presumably similar to the hot spots seen by the IRIS experiment on Voyager. It is possible to extract from these data the total amount of power radiated. Since the hot spots are believed to be a result of deep-seated activity in Io and since the remainder of Io's surface is an extraordinarily poor thermal conductor, the power radiated by the hot spots is essentially the total heat flow. The analysis yields a heat flow of 2 + or - 1 W/sq m. This value is tremendously large in comparison to the average heat flow of the earth (0.06 W/sq m) and the moon (0.02 W/sq m), but is characteristic of active geothermal areas on the earth. A heat flow this large requires that the interior of Io be at least partially molten on a global scale.

Matson, D. L.↗
NASA NTRS1992

Influence of heat flow on early Martian climate

Previous arguments have suggested that the formation of the valley networks on Mars may be explained by higher internal regolith temperatures associated with a much higher heat flow early in the planet's history. It is possible that this higher heat flow could cause groundwater to be closer to the martian surface 3.8 billion years ago, and thus allow the formation of the valley networks by groundwater sapping, without having to invoke surface warming due to an atmospheric greenhouse effect. It was previously shown that, in fact, it may not be possible to completely separate the effects of higher heat flow and atmospheric greenhouse on early Mars. We have more fully explored the parametric space of our set of equations to better determine the sensitivity of the system to variations in any of the factors. The limiting factor in the effectiveness of an atmospheric greenhouse is the total CO2 available in the system. We find that a combination of higher heat flow and atmospheric greenhouse effect on early Mars may more easily explain valley network formation and distribution, even for a cool early sun, than either of these mechanisms separately.

Postawko, Susan↗
NASA NTRS1984

Interpretation of the lunar microwave brightness temperature spectrum - Feasibility of orbital heat flow mapping

The feasibility of an orbital mapping of heat flow by means of microwave radiometers is examined on the basis of a detailed model of the lunar regolith. The results obtained are discussed in terms of contributions of physical properties and regolith structure to the spectral signature of lunation-averaged brightness temperatures. Even for regions for which remote heat flow detection is not feasible, detailed interpretations of remote measurements in terms of physical properties and regolith structure could be made by means of the model presented. Surface and subsurface scattering effects are considered in evaluating possible wavelength dependencies of the microwave emissivity.

Keihm, S. J.↗
NASA NTRS2017

Restoration of the Apollo 15 Heat Flow Experiment Data from 1975 to 1977

The Apollo 15 Heat Flow Experiment (HFE) was conducted from July 1971 through January 1977. Two heat flow probes were deployed roughly 8.5 meters apart. Probe 1 and Probe 2 penetrated to 1.4-meters and 1-meter depths into the lunar regolith, respectively. Temperatures at different depths and the surface were logged with 7.25-minute intervals and transmitted to Earth. At the conclusion of the experiment, only data obtained from July 1971 through December 1974 were processed and archived at the National Space Science Data Center (NSSDC) by the principal investigator of the experiment, Marcus Langseth of Columbia University. Langseth died in 1997. It is not known what happened to the HFE data tapes he used. Current researchers have strong interests in re-examining the HFE data for the full duration of the experiment. We have recovered and processed large portions of the Apollo 15 HFE data from 1975 through 1977 by assembling data and metadata from various sources.

HFE↗
NASA NTRS2001

Modeling Heat Flow In a Calorimeter Equipped With a Textured Solar Collector

Heat engines are being considered for generating electric power for minisatellite applications, particularly for those missions in high radiation threat orbits. To achieve this objective, solar energy must be collected and transported to the hot side of the heat engine. A solar collector is needed having the combined properties of high solar absorptance, low infrared emittance, and high thermal conductivity. To test candidate solar collector concepts, a simple calorimeter was designed, manufactured, and installed in a bench top vacuum chamber to measure heat flow. In addition, a finite element analysis model of the collector/calorimeter combination was made to model this heat flow. The model was tuned based on observations from the as-manufactured collector/calorimeter combination. In addition, the model was exercised to examine other collector concepts, properties, and scale up issues.

Jaworske, Donald A.↗