Showing papers on "Latent heat published in 1973"
TL;DR: In this article, it was shown that the two-dimensional q-component Potts model is equivalent to a staggered ice-type model, and it was deduced that the model has a first-order phase transition for q>4, and a higher-order transition for Q
Abstract: It is shown that the two-dimensional q-component Potts model is equivalent to a staggered ice-type model. It is deduced that the model has a first-order phase transition for q>4, and a higher-order transition for q
559 citations
TL;DR: A three-time level implicit scheme, which is unconditionally stable and convergent, is employed for the numerical solution of phase change problems, on the basis of an analytical approach consisting in the approximation of the latent heat effect by a large heat capacity over a small temperature range as discussed by the authors.
500 citations
TL;DR: In this paper, a simple refinement of McKenzie's model is proposed to account for the evolution of latent heat in places where the plate is growing, and the essential difference stems from the inclusion of terms in the boundary conditions.
Abstract: MCKENZIE'S model of crustal creation at the ocean ridges1,2 and its derivatives3,4 predicts such features as the topography and high heat flow of the ridges. In spite of this success there are some unsatisfactory aspects of the model; for example, the arbitrary temperature distribution in the intrusive zone gives rise to infinite heat generation and the lithospheric thickness is a free parameter not determined by the physics. We offer here a simple refinement of McKenzie's model that overcomes these difficulties. The essential difference stems from the inclusion of terms in the boundary conditions to account for the evolution of latent heat in places where the plate is growing. We first describe the physical basis of the model.
472 citations
TL;DR: In this article, a table of thermodynamic properties of nitrogen is presented for the liquid and vapor phases for temperatures from the freezing line to 2000 K and pressures to 10,000 bar.
Abstract: Tables of thermodynamic properties of nitrogen are presented for the liquid and vapor phases for temperatures from the freezing line to 2000 K and pressures to 10,000 bar. The tables include values of density, internal energy, enthalpy, entropy, isochoric heat capacity (Cv), isobaric heat capacity (Cp), velocity of sound, the isotherm derivative (∂P/∂ρ)τ, and the isochor derivative (∂P/∂T)ρ. The thermodynamic property tables are based on an equation of state, P=P (ρ,T), which accurately represents liquid and gaseous nitrogen for the range of pressures and temperatures covered by the tables. Comparisons of property values calculated from the equation of state with measured values for P‐ρ‐T, heat capacity, enthalpy, latent heat, and velocity of sound are included to illustrate the agreement between the experimental data and the tables of properties presented here. The coefficients of the equation of state were determined by a weighted least squares fit to selected P‐ρ‐T data and, simultaneously, to Cv data ...
269 citations
TL;DR: In this article, a generalized technique for fluid modeling of critical heat flux is developed from classical dimensional analysis and theory of models, and the problem of multiple distortion is solved by introducing a modeling parameter which is a function of Weber number and liquid and vapor superficial Reynolds numbers.
114 citations
TL;DR: In this paper, an analytical solution to predict the temperature distribution and the motion of the interface in a pure liquid or eutectic alloy solidifying or melting in a wedge shaped enclosure was obtained by the superposition of the solutions to two auxiliary problems.
87 citations
TL;DR: Aircraft measurements of sensible and latent heat fluxes, surface and air temperature, mean wind and humidity were used to examine the boundary layer structure over the Great Lakes for two cases in late fall when the water was warmer than the air above as mentioned in this paper.
Abstract: Aircraft measurements of sensible and latent heat fluxes, surface and air temperature, mean wind and humidity were used to examine the boundary layer structure over the Great Lakes for two cases in late fall when the water was warmer than the air above. The sensible and latent vertical turbulent heat fluxes at the surface were in the range 5–10 mW em−2, and 6–15 mW em−3, respectively. Estimates of the mean vertical velocity at the interface between the mixed layer (where the equivalent potential temperature lapse rate was ∼1C km−1 and the mixing ratio was effectively constant) and the stable air above were obtained from the equations for the rate of change of sensible plus latent heat and of water vapor in the boundary layer. The values obtained by this method appear to be reasonable when compared with estimates obtained from the wind field. Using this mean vertical velocity, the vertical fluxes of latent and sensible heat and liquid water in the cloud layer just below the top of the mixed layer ...
71 citations
TL;DR: In this paper, a model for airflow over mountainous terrain is presented, where the equations for steady, two-dimensional, laminar inviscid flow, including pseudo-adiabatic latent heat release, are derived.
Abstract: A model for airflow over mountainous terrain is presented. The equations for steady, two-dimensional, laminar inviscid flow, including pseudo-adiabatic latent heat release, are derived. Approximate solutions to the linearized equations are obtained for stably stratified conditions, and a terrain consisting of broad ridges (width≳25 km), through an iterative transform technique which allows the nonlinear boundary conditions to be satisfied. The model indicates that the dynamical effects of latent heat are significant in some cases but are generally secondary to the barrier effect of the terrain.
55 citations
TL;DR: A sonic anemometer, lyman alpha humidiometer, and thermistor thermometer were operated on ice at 75°N, 15°W in March-April 1972 as part of the Aidjex pilot study as mentioned in this paper.
Abstract: A sonic anemometer, lyman alpha humidiometer, and thermistor thermometer were operated on ice at 75°N, 15°W in March-April 1972 as part of the Aidjex pilot study. Spectra of temperature and humidity fluctuations and cospectra for the sensible and latent heat fluxes were similar to those published for neutral conditions over sea and land. Bulk transfer coefficients were CT = 1.2 × 10−3 and CQ = 0.55 × 10−3, respectively. The Bowen ratio of sensible to latent heat fluxes ranged from 1 to 15 and can be obtained from values of the temperature and humidity spectra at low frequencies except when the latent heat flux is very small. These data were recorded at the spring equinox, and the dominant feature of the heat fluxes is their diurnal variation. Evaporation continued for several hours after the sensible heat flux changed to the downward direction. Over Robeson Channel in July 1972 the heat transfer coefficient was CT = 1.0 × 10−3 for stable conditions.
47 citations
TL;DR: In this article, it was shown that small reductions of tropical sea surface temperatures during ice ages are associated with substantial reductions in latent heat release and in the temperature of the upper tropical troposphere.
Abstract: Small reductions of tropical sea surface temperatures during ice ages are associated with substantial reductions in latent heat release and in the temperature of the upper tropical troposphere. Numerical simulations confirm that this reduced the mean baroclinicity during ice age winters and presumably the atmospheric heat transport from low to high latitudes. The computed wind driven ocean circulation was also weaker. Local heat balance considerations suggest that ice age cloud cover over the tropical oceans was more extensive inl spite of reduced evaporation and precipitation. The same deduction is suggested by analytical arguments about atmospheric convection.
46 citations
TL;DR: In this article, an indirect method is developed in which Cn is calculated from the estimates of sensible and latent heat flux components of the surface energy budgets, primarily for heights less than 4 meters, because low intermittency and a near-unity value of the ratio of the eddy diffusivity of heat to that of momentum are assumed.
Abstract: The refractive index structure function coefficient Cn2 is an atmospheric parameter needed to describe scintillation and small-scale phase fluctuations of electromagnetic radiation propagated in the atmospheric surface layer. Since systematic direct measurements of Cn for many climates and seasons are not available, an indirect method is developed in which Cn is calculated from the estimates of sensible and latent heat flux components of the surface energy budgets. This indirect method is primarily for heights less than 4 meters, because low intermittency and a near-unity value of the ratio of the eddy diffusivity of heat to that of momentum are assumed. Diurnal variations of Cn at several heights above land for six combinations of climates, seasons, and surface conditions are calculated from heat fluxes measured by different investigators at many locations for moderate to high wind velocities. These predictions of Cn agree well with some direct measurements of Cn when assumptions of nearly ideal weather and sites are met. The effect of water vapor on Cn is usually an increase of about 16/β%, where β is Bowen's ratio, and thus is usually negligible above dry land but can be significant above wet surfaces.
TL;DR: In this paper, the vaporization or condensation rate of a motionless liquid droplet using the quasi-steady diffusion-controlled model was investigated. But the authors only considered a single component of the droplet and did not consider a series of pure hydrocarbon liquids.
Abstract: This theoretical investigation deals with the vaporization or condensation rate of a motionless liquid droplet using the quasi-steady diffusion-controlled model. A single-component liquid droplet is considered to be undergoing a phase change within a binary mixture of ideal gases (vapor plus noncondensable gas). Droplet vaporization rates corresponding to specified ambient conditions have been calculated by numerical solution of the variable-property governing equations. Results are presented for water and a series of pure hydrocarbon liquids for a range of ambient conditions of interest. A dimensionless correlation is given for the hydrocarbon vaporization and condensation rates. The pressure variation in the region surrounding a droplet undergoing vaporization or condensation has been investigated by numerical integration of the momentum equation. The resulting calculations indicate that the pressure decreases with increasing distance from the droplet for condensation as well as vaporization. Finally, criteria are given for estimating when the pressure gradient and viscous dissipation may be of significance in the energy equation.
TL;DR: In this paper, the experimental reliability of the use of the energy balance model in energy budget calculations in a deciduous forest has been studied, where data were collected from three towers located in a mixed hardwood stand.
Abstract: The question of the experimental reliability of the use of the energy balance model in energy budget calculations in a deciduous forest has been studied. Data were collected from three towers located in a mixed hardwood stand. Diurnal profiles of sensible and latent heat are presented. The largest absolute differences in the energy budget terms occurred as a result of variations in the net radiation. These variations were consistent over the entire season, such that they cannot be eliminated by temporal averaging. The effects of the variations in the temperature and moisture profiles were found not to be significant in the energy balance calculation under uniform wind and good fetch conditions. However, during periods with shifting winds the variability resulting from the temperature and moisture profiles was unacceptably large.
01 Aug 1973
TL;DR: In this article, a finite element method is developed for the solution of heat conduction problems which involve latent heat, which allows a wider range of material properties and boundary conditions to be dealt with, such as are encountered in complex engineering operations like ground freezing.
Abstract: The Application of Finite Elements to Heat Conduction Problems Involving Latent Heat
A finite element method is developed for the solution of heat conduction problems which involve latent heat. The method is superior to other wellknown approaches to these problems in that it allows a wider range of material properties and boundary conditions to be dealt with, such as are encountered in complex engineering operations like ground freezing. The method is applied to simple triangular finite elements in this paper, although it could be extended to other types of element including three-dimensional ones. Several example problems are discussed and illustrated, and comparisons are made with other approaches where these can also be used.
TL;DR: In this paper, it was shown that the growth rate of droplets near the critical size is exponential when the heat transfer rate is moderately slow, unless the supersaturation ratio exceeds a critical value.
Abstract: In nucleation theory the rate of growth of droplets near the ``critical size'' is needed as a function of the supersaturation ratio and of the equilibration time for heat transfer to the carrier gas. If the droplet is sufficiently small, the latent heat deposited when one molecule is added heats the droplet sufficiently for the evaporation rate to be increased appreciably. It is shown that the net growth rate is ``exponentially small'' when the heat transfer rate is moderately slow, unless the supersaturation ratio exceeds a critical value. Approximations are derived for this small growth rate under various conditions.
TL;DR: In this article, the temperature distribution in a crystal-melt system solidifying with a planar interface is examined and the limiting interface heating is found to be the latent heat divided by the specific heat, which can be quite large.
TL;DR: In this article, a technique due to Saunders is used to give quantitative information on the amount of heating to be realized from the freezing of liquid water in a cloud, and the commonly accepted value of ⅓C per gram of water frozen per kilogram of air plus an additional amount due to saturation adjustment from water to ice is shown to be imprecise.
Abstract: A technique due to Saunders is used to give quantitative information on the amount of heating to be realized from the freezing of liquid water in a cloud. The commonly accepted value of ⅓C per gram of water frozen per kilogram of air plus an additional amount due to saturation adjustment from water to ice is shown to be imprecise. The total heating is realized only after ice pseudo- or saturated-adiabatic ascent to higher levels in the atmosphere; less than one-half of the maximum temperature difference between liquid water and ice processes is realized at the time of freezing, if freezing of cloud contents of 7 gm kg−1 or less is done at −5C. The delay in the freezing of rainwater in operational, one-dimensional numerical models biases the results against natural clouds, leading to overestimates of “seedability.” Also the neglect of the temperature dependence of the latent heat of condensation (increasing with lower temperatures) in those models causes the same kind of bias.
10 Jul 1973
TL;DR: In this article, a multi-level model based on primitive equations was developed for simulating the temperature and velocity fields produced in the world ocean by differential heating and surface wind stress.
Abstract: A multi-level model, based on the primitive equations, is developed for simulating the temperature and velocity fields produced in the world ocean by differential heating and surface wind stress. The model ocean has constant depth, free slip at the lower boundary, and neglects momentum advection; so that there is no energy exchange between the barotropic and baroclinic components of the motion, although the former influences the latter through temperature advection. The ocean model was designed to be coupled to the UCLA atmospheric general circulation model, for the study of the dynamics of climate and climate changes. But here, the model is tested by prescribing the observed seasonally varying surface wind stress and the incident solar radiation, the surface air temperature and humidity, cloudiness and the surface wind speed, which, together with the predicted ocean surface temperature, determine the surface flux of radiant energy, sensible heat and latent heat.
TL;DR: In this article, the authors combined sensible and latent heat fluxes from measurements taken aboard a ship and from a spar buoy east of Barbados in August 1968 with radiation measurements to obtain a sequence of total heat exchange across the sea-air interface.
Abstract: Computations of sensible and latent heat fluxes from measurements taken aboard a ship and from a spar buoy east of Barbados in August 1968 are combined with radiation measurements to obtain a sequence of total heat exchange across the sea-air interface. It is shown that there is a strong correlation between convective activity and latent heat flux. Under moderately depressed convective activity the ocean is estimated to gain heat at a daily average rate as high as 385 ly day−1 (193 w m−2), whereas under extremely enhanced convective activity the ocean is estimated to lose heat at a rate of 275 ly day−1 (138 w m−2) averaged over a few hours.
TL;DR: In this article, an improved quasi-Lagrangian primitive equation model is used to investigate existing cumulus parameterization schemes, and compared forty-eight hour forecasts were made utilizing seven different cumulus heating functions, one being zero cumulus latent heat release.
Abstract: An improved quasi-Lagrangian primitive equation model is used to investigate existing cumulus parameterization schemes. Comparative forty-eight hour forecasts were made utilizing seven different cumulus heating functions, one being zero cumulus latent heat release. Initial data were that of a nondeveloping easterly wave in the Carribbean. Of the six forecasts which included latent heat release, two predictions involving a time-independent vertical heat release function proved to be the most errant. The parameterized heating of Krishnamurti and Moxim, Yamasaki with time-dependent heat release function, convective adjustment, and cumulus scale mass conservation, produced comparable results. Time mean maximum ascending motions of the four similar forecasts ranged from a low of ?2 times 10 ?4 mb sec ?1 with Krishnamurti & Moxim heating to a high of near ?6 times 10 ?4 mb sec ?1 for Yamasaki heating. Convective adjustment and cumulus scale mass conservation techniques tended to produce poorer low-level forecasts because of a strong dependency upon the initial moisture distribution. Concurring results among forecasts were consistent with the previous tropical scale analysis of Charney. For the easterly wave of moderate intensity, computed vertical motions indicated essentially no coupling of upper and lower tropospheric motion outside convective areas and only minimal coupling in regions of cumulus latent heat release. Seventy to eighty percent of the ascending motion and eddy kinetic energy produced within the wave was estimated to be the direct result of parameterized cumulus latent heat release. DOI: 10.1111/j.2153-3490.1973.tb00630.x
TL;DR: In this paper, a flat leaf-shaped plates of both surfaces wetted and covered with thin polyethylene sheet was designed and calibrated, whose leading edge was set on a plane and thermal insulators hold them.
Abstract: A new evaporimeter with flat leaf-shaped plates of both surfaces wetted was designed and calibrated. This equipment consists of a set of two this 5cm×5cm flat plates within which electrical resistor-sheets of uniform resistance are enclosed. One of the plates has the evaporating surface of filter-paper wetted and the other has the non-evaporating surface covered with thin polyethylene sheet. These two plates whose leading edge being in line, are set on a plane and thermal insulators hold them. Water is supplied to the evaporating surface from a small reservoir, homogeneously in the transverse direction along cotton thread through vinyl tubes.Electric power consumed in the non-evaporator is kept at a constant value, and caloric value caused by electrically heating the evaporator is adjusted so that the local surface-temperatures of the evaporator and non-evaporator at the identical position become to be equal. Then, from the difference between the equations of local heat-balance of both plates at a distance of xcm from the leading edge, neglecting heatconduction within the plates, under the condition of identical absorptivities to solar and infrared irradiations and heat capacities of the plates, the following equation is written;Lwx=Q-Q′, where, wx is local evaporation rate in g/cm2 sec, L; heat of vaporization of water (cal/g), Q and Q′; electric power consumed per unit area of evaporating and non-evaporating plates (cal/cm2 sec), respectively.Here, local evaporation rate of a plane surface can be obtained from the electric power compensating the latent heat of vaporization in evaporating surface.Coefficient of local transfer of water-vapor by forced convection, Df, x (cm/sec), is evaluated from the following equation;Df, x=Dx, EXP-Dn, CALC, where, Dx, EXP=wx/2ΔCx and ΔCx=CE, x-cA(g/cm3); difference in vapor concentration between the wet surface (CE, X) and the air outside the boundary layer on the surface (CA), Dn, CALL=0.405 (Gr'·Sc)0.25 d/l; calculated value of average coefficient of water vapor transfer from the upper and lower surfaces of the plate for free convection, Gr′; Grashof number in vapor transfer, Sc; Schmidt number, d; molecular diffusivity of water vapor to air (cm2/sec), l; dimension of the surface along the wind-direction (cm).As the results of some tests by means of a wind tunnel in which average intensity of turbulence was about 0.6%, the local water-vapor transfer coefficient at x=2cm was obtained as follows;in the range of Rex under 2×104, Df, x=1.15⋅λ⋅0.332Sc1/3⋅Rex0.5⋅d/x, where, λ is the correction factor for the effect of vapor concentration-departure distribution on evaporating surface, Rex; local Reynolds number.The above expression of Df, x showed the property of the transfer coefficient for laminar boundary layer.
TL;DR: In this paper, the authors consider the gas-liquid first-order phase transitions and prove the existence of the critical point in white dwarf matter, where the latent heat released in the liquefaction processes can be used in the interpretation of the spreading of the white dwarf sequence in H-R diagram.
Abstract: We consider the gas-liquid first-order phase transitions and prove the existence of the critical point in white dwarf matter. The latent heat released in the liquefaction processes can be used in the interpretation of the spreading of the white dwarf sequence in H-R diagram. Some thermodynamic quantities, e.g., the saturation pressure, the latent heat, etc., are calculated along the gas-liquid coexistence curve, and their behaviour near critical point are studied.
TL;DR: In this paper, it was shown that a correlation can be established between the heat of vaporization and the Raman frequencies for normal hydrocarbons at equal pressures for several classes of compounds.
Patent•
24 Aug 1973
TL;DR: An incubator for transporting babies while keeping them, during the transportation, under a constant ambient temperature is thermally insulated on all sides and comprises in the interior receptacles containing a chemical compound preferably tetradecyl alcohol having a melting temperature between 30-40.degree as discussed by the authors.
Abstract: An incubator for transporting babies while keeping them, during the transportation, under a constant ambient temperature is thermally insulated on all sides and comprises in the interior receptacles containing a chemical compound preferably tetradecyl alcohol having a melting temperature between 30-40.degree.C and emitting latent heat when cooling down and crystallizing, this emitted heat being sufficient to compensate heat losses during transportation of the incubator and so to maintain the inner temperature for a certain time without heat supply. Before the transportation the chemical substance is melted by means of an electric heating device supplied from the outside and a thermostat keeps the inner temperature, before the transportation, slightly above the melting point of the substance.
01 Jan 1973
TL;DR: In this article, a traditional folksong asks "Why did they put the shore so near the ocean?” Whatever the reason, it is indeed fortunate that "they" did.
Abstract: A traditional folksong asks “Why did they put the shore so near the ocean?” Whatever the reason, it is indeed fortunate that “they” did. The gallon or cubic meter of desalted sea water will be cheaper if delivered for use in coastal regions rather than in higher inland locations.
01 Mar 1973
TL;DR: In this article, methods of computation and error estimates for numerical approximation of selected meteorological parameters used in the solution of cloud physics problems are presented for FORTRAN programming language listings of the approximations.
Abstract: : Methods of computation and error estimates are presented for numerical approximation of selected meteorological parameters used in the solution of cloud physics problems. These parameters are latent heat, saturation vapor pressure, dew point and wet bulb temperatures, specific heat of liquid water, temperature of the lifting condensation level, change in mass of freely falling water drops, and saturation-adiabatic temperatures. The FORTRAN programming language listings of the approximations are provided in the appendix.
Patent•
11 Jul 1973TL;DR: In this article, a sealed tube containing a heat transport fluid is positioned in heat exchange relation with those exterior surfaces of a pyrolytic self-cleaning oven which are raised to relatively high temperatures during the heat cleaning cycle.
Abstract: A sealed tube containing a heat transport fluid is positioned in heat exchange relation with those exterior surfaces of a pyrolytic self-cleaning oven which are raised to relatively high temperatures during the heat cleaning cycle. The heat transport fluid boils and the vapor is directed by the tube away from the hot exterior surfaces and is placed in heat exchange relation with other parts of the range which are at relatively cooler temperatures and can therefore be used as a heat sink. At these cooler locations, condensation of the transport fluid occurs and thereby removes the latent heat of vaporization of the fluid from the hot surfaces.
TL;DR: In this paper, a non-linear, three-dimensional spectral model on a β-plane is developed to study the relative rǒles of important energy sources for tropical waves.
Abstract: A non-linear, three-dimensional spectral model on a β-plane is developed to study the relative rǒles of important energy sources for tropical waves. Both the north-south shear of the zonal wind and Cisk (conditional instability of the second kind) are included. Energy exchanges and wave growth rates are studied in the presence of various specified vertical profiles of latent heat. Radiation is parameterized by Newtonian cooling; it plays a minor rǒle. Latent heat is parameterized in terms of large-scale boundary layer flow. Dissipation is also included.
The model includes three layers in the troposphere and one in the stratosphere. The top of the boundary layer is taken at 900 mb and its effect is described by frictionally induced vertical velocity and surface dissipation. The initial state is an idealized form of observations taken in the Marshall Islands.
Important results show that when latent heat release decreases with height and is large at low tropospheric levels, the eddies are initially generated and maintained barotropically and then Cisk assumes a dominating rǒle. When heat release increases with height, Cisk dominates at all stages of the wave development; the barotropic mechanism, however, is still necessary.
It is also found that when latent heat release is maximum at the low levels, the most dominant wave is 3,000 km with an initial growth rate of 3 days in e-folding time. The longer waves assume greater dominance at the upper levels, especially when latent heat increases with height.