Showing papers on "Latent heat published in 1969"

Anemoclinometer measurements of reynolds stress and heat transport in the atmospheric surface layer

Abstract: : A small, three-dimensional pressure-probe anemometer (IMFL anemoclinometer) was used to measure the three components of the wind vector, shear stress, and the ratio of the standard deviation of the vertical wind to the friction velocity as influenced by atmospheric stability. Horizontal wind and shear stress have been compared with independent wind profile and shear stress meter measurements. The anemometer was coupled with a fast thermometer for eddy correlation measurements of sensible heat flux and with a fast hygrometer for measurements of latent heat flux. The eddy correlation measurements of sensible and latent heat fluxes were compared with independent energy balance, wind profile, and sonic anemometer-thermometer measurements.

Part 1. Dynamic Response of Phase Boundaries in the Earth to Surface Loading. Part 2. Pleistocene Glaciation and the Viscosity of the Lower Mantle

Abstract: Part 1. Analytic approximate solutions have been found for the response of a phase change to pressure loading. These solutions allow the behavior of the system to be analyzed in terms of simple parameters of the system. Different characteristic types of behavior are shown to obtain for short times and long times, and criteria for defining these characteristic time scales are given in terms of known parameters. The distribution of heat sources and convective heat transport are shown to generally have only minor influence on the solution, and may be neglected in many cases. The important parameters are the latent heat of the phase change, and the difference between the Clapeyron slope and the temperature gradient at the phase boundary; in addition the long term behavior is governed by the boundary conditions at the surface and at depth, and the relative positions of the surface, the phase boundary, and the lower boundary. The effect of thermal blanketing from sediments is included in the solution, and it depends primarily on the depth of the phase boundary and the average temperature gradient in the sediments. The effect of isostasy in conjunction with a phase change is shown to be of major importance; the existence of instabilities where the water depth increases with sedimentation are demonstrated. These solutions allow the history of a sedimentary basin to be calculated, and characterized in terms of certain types of behavior. The existence of oscillatory behavior is demonstrated, where repeated cycles of sedimentation and erosion take place. These oscillations can either decay or grow in amplitude, and expressions are given for their frequency and damping or growth constants. A phase change mechanism can account for thicknesses of sediments which exceed the depth of the basin in which they were deposited by a factor of twenty or more. These solutions allow the discussion of the geological implications of phase changes in a quantitative manner. The consequences of a phase change can be accurately calculated. This will allow the more complete investigation of the role of phase changes in geologic processes. Part 2. The non-tidal acceleration of the earth, revealed by astronomical observations and records of eclipses in antiquity, is attributed to the change in the earth's moment of inertia resulting from isostatic response to the most recent deglaciation and rise in sea level. The isostatic response time for a spherical harmonic deformation of degree two is calculated on this basis to be either ~2000 years or ~100,000 years. A correlation of the geopotential with the potential that would have existed following de glaciation indicates that any large scale anomalies resulting from deglaciation have already decayed. This rules out the 100,000 relaxation time; thus the relaxation time of the earth is ~2000 years for degree two. Calculations of the relaxation time spectrum of a layered, gravitating spherical viscous earth model indicates that a model with a uniform mantle viscosity of ~10^(22) poise, except for fine structure in the upper few hundred kilometers, can satisfy the relaxation time of 3000 years for degree two as well as the relaxation time of ~4000 years for degree twenty which results from studies of uplift in Fennoscandia. A zone of high viscosity in the lower 800 km. of the mantle has a significant effect on the degree two relaxation time. This rules out any substantial increase in viscosity in the lower mantle. The calculated viscosity permits rapid polar wandering and convection in the lower mantle.

Observational studies of the general circulation of the Tropics: long term mean values

Abstract: Data from 298 stations between 45°N and 30°S have been processed for the period July 1957 to December 1964 The mean wind and temperature fields are presented together with the momentum and heat fluxes for two three month seasons, December-February and June-August The tropospheric results were obtained from objective analysis of the long term station means and the stratospheric results from latitude band means giving equal weight to data from odd and even years so that the biennial component has been virtually eliminated The mean temperature cross-sections show little seasonal variation in the tropical troposphere and gradients are small The maximum temperature is in the vicinity of 5°S during the southern summer but moves to 20°N during June-August as a consequence of stronger heating over the continents In the tropical stratosphere the seasonal variation is from lower temperatures in December-February to higher temperatures in June-August The mean zonal wind pattern shows the tropical easterlies to be stronger and to occupy a greater range of latitudes in the upper troposphere during June-August The Hadley circulation obtained appears quite reasonable with the winter hemisphere cell predominating and extending over the Equator Although all three components of the momentum flux were evaluated for the troposphere, only the transient eddy contribution could be obtained for the stratosphere A strong flux is observed in the upper equatorial troposphere directed into the summer hemisphere The sensible heat-flux in the middle troposphere is equatorward in the Tropics of both hemispheres and a small transport into the summer hemisphere is noted This equatorward flux is countergradient in both hemispheres except during the northern summer The mean motion transport of total energy is about an order of magnitude larger than the eddy transport at the Equator and supplies energy to the winter hemisphere The zonal and eddy forms of kinetic energy and available potential energy have been evaluated for the tropical troposphere together with all conversions between them except for that by transient eddies between available potential energy and kinetic energy On the average, kinetic energy contents are about twice as large as available potential energy contents and the momentum flux conversions are larger than those involving heat fluxes The conversion by the mean motions, however, is largest of all over the range 24°N-24°S and leads to a rejuvenation time of some 3–5 days for the zonal kinetic energy This conversion appears to be sufficiently large to offset the destruction in middle latitudes Taken together, the results presented here give a consistent pattern for the tropical circulation The direct Hadley cell is seen as a source of both heat and momentum which are distributed by the eddy fluxes The energy supply for the mean cell is thought to be the latent heat of condensation in its ascending branch

A preliminary prediction analysis of radiation fog

Abstract: The system of physical equations describing temperature changes near the ground in fog-free air as well as in radiation fog is solved numerically. The variation of the exchange coefficient with height is taken into account using different models while time variations are still disregarded. Temperature changes due to latent heat effects are incorporated in this study. Moreover, the presence of radiative flux divergence is included in an approximate manner. The solution of the problem is presented in terms of graphs showing the development of temperature and water droplet profiles as function of time and height. Computed liquid water content as well as temperature profiles are in general agreement with observations while the vertical growth of fog usually proceeds too rapidly. Concrete suggestions are given of how to improve the model.

The specific heat of solid oxygen

Abstract: Measurements have been made in the temperature range from 1.3° K to about 71°K with particular attention to the behavior at very low temperatures, and in the neighborhood of the α-β transition at about 23.89° K. Assuming that near 0° K each molecule moves as a single mass point with the passage of lattice waves, the effective Debye temperature at 0° K is extrapolated to be 104±2° K. As the temperature rises above 10° K, the specific heat rises more rapidly than a reasonable Debye model would predict, suggesting the appearance of additional degrees of freedom, which are thought to be the superposition of a librational motion of the molecules superposed on the longitudinal and transverse lattice waves controlling the motion of a molecule's center of mass. The specific heat shows a very sharp high “spike” at the α-β transition with an entropy change of aboutR ln 1.65; there is no evidence for a latent heat associated with this transition.

A short term heat balance study on a coast range glacier

Abstract: A short term heat balance study made on the Lemon Glacier, Juneau Icefield, Alaska is described. Of the energy required to give the observed melting of the firn the net radiation over all wavelengths contributed 49%, the latent heat 8%, and the sensible heat a large 43%. The approximate equality between the net radiative component and the total eddy heat transfer is similar to the results of a previous determination on an Alaskan glacier in summer, though the latent and sensible heat proportions are different in each case.

Mars: Theoretical Aspects of Meteorology

Abstract: The Mars atmosphere responds by radiative and convective heating to surface temperature changes in a time-scale of the order of one day. This is about 50 times as fast as the corresponding response on the earth. As a consequence, the mean wind distribution is under strong solar control but may be modified by latent heat release in CO2 condensation and by the mass flow required to balance such condensation. Unstable eddies, analogous to terrestrial cyclones, are to be expected in all seasons except summer. The thermally driven tides are likely to be strong on Mars, but a detailed theoretical solution to this problem has yet to be given.

Analytical Calculations For Heat Transfer From Fractures

Abstract: Successful thermal recovery processes require injection rates which in some reservoirs are attainable only by fracturing the formation. To increase understanding of thermal processes in fractured systems, 3 new analytical models are developed which relate temperature as a function of time and position to injection conditions and reservoir characteristics. The model for hot-water injection into a vertical fracture accounts for convection of energy in the fracture, conduction and convection in the pay sand, and conduction in the overburden. The steam injection model takes into account convection and condensation in a vertical fracture and conduction in the formation. A special radial case is also presented for those interested in heat transfer from a very thin, permeable zone. The latent heat model accounts for conduction and convection of energy in the pay sand and conduction in adjacent strata. The report deals primarily with the derivations of the 3 models. (11 refs.)

Thermally cascaded thermoelectric generator

Abstract: A THERMALL CASCADED THERMOELECTRIC GENERATOR IS DISCLOSED. THE GNENERATOR INCLUDES A FIRST STAGE CONTAINING HIGHTEMPERATURE THERMOELECTRIC ELEMENTS AND A SECOND STAGE CONTAINING LOWER TEMPERATURE THERMOELECTRIC ELEMENTS. THE STAGES ARE CONNECTED IN THERMAL SERIES BY MEANS OF AN ELONGATED HEAT TRANSFER PIPE CONTAINING A LIQUID METAL AND A WICK. A PORTION OF THE HEAT RADIATED TO THE FIRST STAGE FROM A HIGH-TEMPERATURE RADIOISOTOPE SOURCE IS CONVERTED TO ELECTRICITY. THE HEAT REJECTED BY THE FIRST STAGE IS CONDUCTED TO THE HEAT PIPE AND ABSORBED BY THE LIQUID METAL AS LATENT HEAT OF VAPORIZATION. THE VAPOR RISED TO THE SECOND STAGE AND CONDENSES TO GIVE UP LATENT HEAT OF CONDENSATION WHICH IS TRANSFERRED TO THE SECOND STAGE AND IS CONVERTED TO ELECTRICITY THEREIN. THE CONDENSED LIQUID RETURNS ON THE WICK TO THE VICINITY OF THE FIRST STAGE.

a Simple Method of Including Longwave Radiation in a Tropospheric Numerical Prediction MODEL1

Abstract: A simple method of computing longwave radiative cooling in the troposphere associated with water vapor is described. The procedure may readily be incorporated into a tropospheric numerical prediction model. Radiation from ozone and carbon dioxide is not considered. However, influences of arbitrary vertical distributions of cloud and moisture are included. Average annual cooling rates along a meridional cross section are calculated for a cloudless atmosphere. The results agree fairly well with the total radiative cooling (longwave and shortwave) as given by Manabe and Moller except in the lower troposphere at low latitudes. Here shortwave absorption by water vapor is appreciable. The three-dimensional distribution of longwave radiative cooling is also computed in a case of a developing cyclone for comparison with that of release of latent heat. The largest cooling occurs at cloud top and can be a significant fraction of the amount of energy released as latent heat in the upper troposphere. Computa...

On the estimates of heat and moisture over the Indian monsoon trough zone

Abstract: Based on mean radiosonde/Rawin data for July–August for stations around the monsoon trough over India estimates of sensible and latent heat energy through the entire troposphere have been made. A quasi-eliptical boundary defined by 17 aerological stations containing the monsoon trough has been chosen for the study. The mean tropospheric circulation is briefly described. Mass and energy fluxes are evaluated. The computations show mass inflow at all levels up to 600 mb and outflow above 500 mb. The total energy shows a maximum in the lower troposphere and in the upper troposphere with a minimum in the middle troposphere. The flux computations show an export of sensible heat of 8.8 times 10 18 calories per day and an import of 16.07 times 10 18 calories per day through latent heat. DOI: 10.1111/j.2153-3490.1969.tb00418.x

Cooling and lubrication for high speed rotating systems

Abstract: A high speed rotating system driven by a motor which constitutes a source of heat. The system has bearings of porous material through which a liquid coolant is fed and in which heat of friction causes vaporization of the lubricant and hence cooling of the bearing and dissipation of heat from the motor due to the fact that the latent heat of vaporization is derived from the bearing surface and immediately adjacent areas.

Condensation heated black body radiation source

Abstract: An isothermal black body radiation source comprises a double reentrant radiating cavity disposed within a heat pipe Wicking material surrounds the outer surface of the radiating cavity and the heat pipe sidewalls Heat is supplied to the heat pipe by an electrical winding or other suitable heating means, thereby vaporizing a working fluid The vapors are condensed on the cavity outer walls thereby releasing their latent heat of vaporization and heating the cavity wall to a uniform temperature The cavity then radiates energy through an exit aperture In an alternative embodiment the radiating cavity is disposed within a reflux tube

The Mechanism of Microgel Formation in Partially Hydrolyzed Polyacrylamide

Abstract: An equation is presented that allows a more realistic calculation of the steam zone area by including consideration of both the latent heat and the sensible heat in saturated steam. Equations are given which can be used to predict growth of the steam zone for the 2 extreme cases of vertical conformance--severe steam channeling and uniform vertical contact. The equations can also be used to interpret results of an actual field test. For example, calculations indicate the extent of the hot water bank to be expected in each case. This might be correlated with temperature response of a producing well to determine if steam is channeling. The equations do not provide the temperature distribution in the hot water bank ahead of the steam zone. However, a reasonable approximation is a linear distribution starting from steam temperature at the steam front and passing through the mid-point of the heat front.

A mercury transition cell for high pressure calibrations

Abstract: A cell using latent heat detection of the transition is described which enables the melting pressure of mercury at a fixed temperature to be established rapidly. A reproducibility of better than 002 MN m−2 (02 bar) has been obtained at 0°C.

A thermodynamic equation relating equilibrium vapor‐liquid compositions and enthalpy differences in isobaric multicomponent systems

Abstract: A rigorous and simple thermodynamic equation relating equilibrium vapor-liquid compositions and the phase enthalpy differences for a binary, isobaric system is extended to multicomponent systems. An analysis is made to indicate the potential applications of computing the latent heat of vaporization directly from the isobaric vapor-liquid equilibrum data and testing the consistency of phase composition and enthalpy data.

Some Thermodynamic Relations for Superconducting Ellipsoids

Abstract: Under the assumption that no latent heat is associated with the phase changes that occur when a superconducting ellipsoid of type I material (or type II material) enters or leaves the intermediate (or mixed) state in a constant uniform applied field, we expect finite jumps in the specific heat at constant applied field, when these phase changes occur. The jumps are related to the magnetization curves at constant temperature.

Some computations of meridional flow, angular momentum and energy in the atmosphere based on IGY data for latitude 30°N

Abstract: Using basic data extracted from daily hemispherical cross-sections constructed at 30°N for March, June, September and December 1958, extensive numerical calculations of mean meridional flow, angular momentum flux and energy flux (i.e. sensible heat, latent heat, potential and kinetic energy) were carried out, and the principal results are reported. Most of the computations are broadly in agreement with earlier estimates; the main differences are uncertainties concerning the energy transports.

On the energy content of the atmosphere

Abstract: Vertical profiles of the content of sensible heat, potential energy, and latent heat in the atmosphere between 1000 and 100 mb, during January and July, are derived for the latitude circles 0, 10, 20, 30, 40, 50, and 60°N. Contrasts between oceans and continents are found to vary significantly with latitude and season.

Nondimensional Expression for the Relation between Pressure Drop and Flow Rate in Steam Generating Tubes

Abstract: A method to express the relationship between pressure drop and flow rate in steam generating tubes is presented. The characteristics of the pressure drops is represented in nondimensional generalized forms. In a case of uniform heat flux along a tube, it is given by the following equation : ΔP*=2/1κξ3+(1-κ)ξ2+2/1κξ Here, ΔP*=nondimensional pressure drop defined in this report, ξ=nondimensional flow rate, υ"=specific volume of saturated steam, υ'=specific volume of saturated water, r0=subcooling, r=latent heat of evaporation, κ={(υ"/υ')-1}r0/r. The charts in cases of various heat flux distributions along tubes are showm. They can be used to study the influence of each factor such as pressure, subcooling and heat flux distribution and so on characteristics of pressure drop and to estimate the flow stability and the distribution of flow rates in parallel tubes.

Effect of Straw Mulch on Heat Balace

Abstract: Efficts of straw mulch on heat balance items are studied by comparing micrometeorological data of an unmuched plot to those of a mulched plot of 3kg per 3.3m2. The heat storage in the straw was negligible and the mulching caused a higher value of albedo and a greater upward flux of sensible heat than the unmulched plot. Thus the mulching reduced the soil heat and the latent heat fluxes. The albedo of mulch reached the maximum at an amount of 2kg to 3kg per 3.3m2, But the soil heat and the latent heat fluxes decreased with increasing amount of straw applied. In conclusion, the main effect of straw mulch is to increase considerably the sensifle heat flux at the expense of other items of heat balamce.

On the large scale motion in the tropics with latent heat due to condensation

Abstract: A scale analysis for the large scale tropical motions with diabatic heating due to the latent heat of condensation is given. The analysis shows that the diabatic heating term in the thermodynamic energy equation becomes important when the rainfall rate is equal or greater than 2 mm per day.