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Tuesday, April 21, 2020 | History

2 edition of frost formation model and its validation under various experimental conditions found in the catalog.

frost formation model and its validation under various experimental conditions

Mark A Dietenberger

frost formation model and its validation under various experimental conditions

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  • 14 Currently reading

Published by National Aeronautics and Space Administration, Scientific and Technical Information Branch, For sale by the National Technical Information Service] in Washington, D.C, [Springfield, Va .
Written in English

    Subjects:
  • Frost -- Mathematical models

  • Edition Notes

    StatementMark A. Dietenberger ; prepared for Marshall Space Flight Center under contract NAS8-33369
    SeriesNASA contractor report -- 3595
    ContributionsGeorge C. Marshall Space Flight Center, United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch, University of Dayton. Applied Systems Analysis Section
    The Physical Object
    Paginationxi, 57 p. :
    Number of Pages57
    ID Numbers
    Open LibraryOL14931041M

    The thermal-hydraulic performance under conditions of an initial frost growth on the air-side surface, and for subsequent 'refrosting' after a defrost period is experimentally studied for folded-louvered-fin, microchannel heat by: In Jones et al. found that osteoblasts moved laterally in vivo and in vitro under different experimental conditions and escribed the migration method in detail. The osteoblasts were, however, contaminated by cells migrating from the vascular openings, which might include endothelial cells and on: Formation of bone tissue. develop if the frost depth increases to the point where freezing occurs under the foundation. If the soil expands upon freezing (frost susceptible soil) large uplifting forces can be applied to the foundation system [2]. If foundation designers are to avoid these problems, they require informa- tion about frost in soils surrounding foundations.   Teak (Tectona grandis L.f.) is currently the preferred choice of the timber trade for fabrication of woody products due to its extraordinary qualities and is widely grown around the world. Gene expression studies are essential to explore wood formation of vascular plants, and quantitative real-time reverse transcription PCR (qRT-PCR) is a sensitive technique employed Cited by:

    For a dark poem, Frost sure picked a weird color to focus on. Actually, that's kind of the point. He contrasts the light innocence of white with the potentially evil design behind their color scheme. Lines In the first three lines, he repeats the word "white" three times. The spider, the flower and the moth are all white.


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frost formation model and its validation under various experimental conditions by Mark A Dietenberger Download PDF EPUB FB2

FROST FORMATION MODELING APPLIED TO VARIOUS DATA SETS SECTION 1 INTRODUCTION Frost formation commonly occurs when a surface in the presence of humid air is cooled to temperatures below 0°C and below the Size: 3MB. Additional Physical Format: Online version: Dietenberger, Mark.

Frost formation model and its validation under various experimental conditions. Washington, D.C.: National Aeronautics and Space Administration, Scientific and Technical Information Branch ; [Springfield, Va.

Therefore, in this research work, both of the MES and the melted frost effects are considered in experimental cases and thus the melted frost influence on the MES is further calculated.

In addition, the experimental results could also be used to validate some defrosting : Song Mengjie, Mao Ning. The area near the second row of thermocouples frosted most seriously under condition C, while on the other two conditions the frost processes were similar (The frosts began to form and grow on the centre and then frost edge diffuse to its left under condition A; however, the frosts began to form and grow on the left and then frost edge fast diffuse to the right under condition Cited by: In this study, a multiphase computational fluid dynamics (CFD) model is developed to investigate the heat and mass transfer phenomenon of frost formation under cryogenic conditions.

It is observed from experimental studies that frost formation on a vertical cryogenic surface showed different behaviours compared to refrigeration : Biao Sun, Swapnil Ghatage, Geoffrey M.

Evans, Tejas Bhatelia, Ranjeet P. Utikar, Vishnu K. Pareek. Numerical and Experimental Investigation on Frost Formation on Cold Cylinders.

International organization of Scientific Research 45 | P a g e Following the model proposed by [19], the crystal growth is normal to the surface as shows in Fig. Applying the Cited by: 1. A number of frosting experiments are conducted under various operating conditions.

The experimental results, such as frost formation model and its validation under various experimental conditions book thickness, frost density and frost growth rate, are applied as a database to develop the correlation for calculating the initial frost density, and further to validate the numerical results.

Experiment apparatusCited by: An experimental system of frost deposition on cryogenic-temperature surfaces under natural convection conditions was set up and a series of frost formation experiments were conducted under various conditions, focusing on the frosting phenomena on. In this paper, a new model is proposed to predict the frost formation and growth.

The phenomena of frost formation on a cold surface placed in humid air stream are investigated by this model. The simulation is validated by both experiment and other numerical models.

The results show that this new model is suitable for predicting frost by: The experiments showed that the frost formation on a cold surface generally begins with the formation and growth of condensate droplets, freezing of the super-cooled condensate droplets, formation.

The frosting model was validated by comparing not only the simulated frost thickness but also the corresponding frost weight with experimental data for various conditions. Figure 7 8 Ice volumetric fraction spatial distribution at various times. Experimental conditions are from Mao et a l.

() and Tao et al () PAGE Figure 7 9 Frost temperature spatial distribution at various times. Experimental conditions are from Mao et al. () and Tao et al () PAGE The system can be stopped due to the lower likelihood of precipitation and the slow rate of frost formation at low temperatures (Knollhoff et al.

The supply temperature was varied between °C and snow plowing was initiated when. 2 Modeling the frost formation pro-cess Frost formation types During the process of frost deposition on a cold sur-face several stages of frost formation may be distin-guished.

Hayashi et al. [7] found three periods de-scribing the formation of a frost layer: • the crystal growth period • the frost layer growth period.

An experimental study was carried out on heat and mass transfer rates, growth rates and the density of frost layers on a flat plate in forced convection conditions.

The density and thickness of the frost layers were correlated by the dimensionless parameters introduced in the authors' previous paper [6]. Measured density and thickness of the frost layers are Cited by: In this study, a frost formation model is presented based on a new two-dimensional approach for the growth rate.

For modeling the frost formation over parallel cold plates, the basic transport. The model results for the frost thickness were validated with published experimental data, and model predictions were found to agree well with experimental data.

The formulation was also used to assess the influences of humidity, air to surface temperature difference, and Nusselt number on the frost thickness, it wasFile Size: KB.

Mark A Dietenberger has written: 'A frost formation model and its validation under various experimental conditions' -- subject(s): Mathematical models, Frost Asked in Chemistry Is frost.

Page 1 15th International Refrigeration and Air Conditioning Conference at Purdue, JulyExperimental Evaluation of the Frost Formation Yusuke 1TASHIRO *, 2Mamoru HAMADA 1Mitsubishi Electric Corporation, Living Environmental System Laboratory, Oshika Suruga-ku, Shizuoka, Japan (+, +.

sensible and latent heat transfer rates under transient boundary conditions. The model should be also able to calculate the energy consumption of the coupled heat exchanger-fan system under variable weather and load conditions, involving different degree of water-vapour condensation and frost formation.

Faba bean (Vicia faba L.) is an important pulse crop known for its nitrogen-fixing characteristics and as a disease-break crop in crop rotations. Sowing time, scheduling of supplemental irrigation, and sowing rate are some of the agronomic managements which affect faba bean growth and yield.

The effect of these on faba bean yield can be evaluated using calibrated by: 1. Since in frost formation whereby the water vapor flux enters the frost layer, the state of subsaturation is quite unlikely. If the water vapor flux into the,frost layer is so rapid that homo- geneous nucleation occurs, then a state of supersaturation exists (Reference 11).

An Experimental Study on the Behavior of Frost Formation in the Vertical Plate Heat Exchanger K. Lee for different operating conditions(the temperature, the hwnidity and the velocity of the parallel-plate heat exchanger is examined under the experimental conditions shown in. Experimental Investigations into Frost Formation on Display Cabinet Evaporators in Order to Implement Defrost on Demand Display Cabinet evaporators are prone to frost formation due to water vapour in the air condensing and freezing transfer coefficient for various conditions while table I provides the average values for them.

In this. carried out with five samples with different surface finishings using a purpose-built testing facility. The model was then validated with experimental data obtained in this work and elsewhere (Na and Webb, ).

FROST FORMATION FUNDAMENTALS Certain temperature and humidity conditions are required to initiate the frost formation : Robson O. Piucco, Christian J. Hermes, Claudio Melo, Jader R. Barbosa. Aircraft ground icing can result in decreasing the stability of the aircraft at or shortly after take off.

A theoretical model for frost formation by water vapor on aircraft in atmospheric air has been presented in this study. Frost surface temperature and frost thickness can be obtained by the model. Effects of aircraft surface temperatures and air conditions, such as Author: Li Wen Wang, Dan Dan Xu.

Through comparing different empirical correlations of mass transfer, it is found that the Rans¿Marshall correlation is suitable to be used to account for frost formation under cryogenic conditions. The simulation results show a good agreement with the experimental study in terms of temperature profile.

The mass transfer rate is taken as the. Experimental and Computer Model Results for a Carbon Nanotubes Electrothermal De-Icing System. Wind energy harnessing of the NREL 5 MW reference wind turbine in icing conditions under different operational strategies. The Effects of Leading-Edge Ice Roughness on Downstream Frost by: Also, no-slip conditions are imposed at the cold plate and the frost layer surface.

The boundary conditions applied in this study are shown in Table 2. Energy balance must be satisfied on the frost surface, and its relation between the moist air and frost layer is given by (Lee et al., ): ff f w feff a sv yy yy y y TTm kk hD yy y ρ =. true experimental designs, the researcher can randomly assign test units to experimental groups and treatments to experimental groups.

Examples are: the pretest-posttest control group design, the posttest-only control group design, and the Solomon four-group design. Frost predictions are needed to help the deicing operation decide.

The mechanism of frost formation on aircraft surface under icing conditions has been analyzed. A simple theoretical frost growth prediction model by heat and mass transfer analysis has been presented.

It produces a method to forecast the frost growth tendency. An experimental system for atmospheric frost Cited by: 5.

CH 4 Atmospheric water and weather. STUDY. PLAY. is the same as the latent heat released during fog formation. latent heat is _____ during glacial melt. aborbed. latent heat is released during. frost formation. Relitive humidity increases. a decrease in temp w/o a change in the amount of water vapor in the atmoshere.

detailed description of the model, its validation and the different optimization criteria are reported in a previous work [23]. Direct expansion refrigerator The vapour compression refrigerating groups RGmain,S, RGmain,S,L, RGD, RGE and RGF aremodelled through experimental data available from a manufacturer [25].

The system is based on a File Size: 1MB. Frost will disrupt the smooth flow of air over the wing, adversely affecting its lifting capability The boundary between two different air masses is referred to as a.

Front. The conditions necessary for the formation of cumulonimbus clouds are a lifting action and. unstable, moist air. capacity fade under various operating conditions, using physics-based degradation mechanisms that provide a good fit to experimental data.

Based on a specific product applications, an experimental matrix was designed to illustrate the effects of temperature, depth-of-discharge (DOD), time, and energy. The developed model is simulated under different frost levels and the temperature prediction results are compared with field measurements under similar conditions from the literature.

Next, the use of the developed model is demonstrated through calculation of minimal thermal energy required to prevent frost in a test Prunus armeniaca : Ercan Atam, Se-Woon Hong, Alessia Arteconi. The formation of frost (deposition) releases heat and warms the surroundings.

true If our eyes responded to infrared radiation instead of visible light, clouds would appear black because they are good absorbers of IR. The usefulness of the model in dealing with several engineering problems is also demonstrated, including coal-permeability changes caused by swelling under different stress conditions, coupled hydro-mechanical processes associated with CO 2 geological sequestration in a fractured formation, and evolution of the excavation damage zone related to Author: Hui-Hai Liu.

Special Issue "Computational Fluid Mechanics and Heat Transfer" Special Issue Editors Special Issue Information and vibration of the main shaft under nine different flow rates were systematically investigated and explained preliminarily from the view of inner unstable flow.

The formation of frost is difficult to experimentally control. The nematode Caenorhabditis elegans possesses a unique (with various isoforms) FOXO transcription factor DAF, which is notorious for its role in aging and its regulation by the insulin-PI3K-AKT pathway.

In humans, five genes (including a protein-coding pseudogene) encode for FOXO transcription factors that are targeted by the PI3K-AKT axis, such as in C. Pavement performance in northern climate as encountered in Canada is significantly influenced by frost action.

When it comes to granular materials used in flexible pavement foundations, few study focused on the effect of seasonal frost conditions on the mechanical properties of such materials, mostly because such materials are usually considered as non-sensitive to such .spribes criteria formulated by the Corps of Engineers to meet the needs of its construction in areas of seasonal frost.

The variation of subgrade strength through the seasons is illustrated, and it is indicated that the frost-meltinþ þeriod is critical when conditions are con-' ducive to active frost. The final parameter values (Table 1) were validated by simulating the course of control 3 H-2,4-D accumulation (i.e.

accumulation without inhibitors), demonstrating that the model can predict the shape of accumulation curves under various experimental conditions Cited by: