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  • 1
    Series available for loan
    Series available for loan
    Hanover, NH : U.S. Army Materiel Command, Terrestrial Sciences Center, Cold Regions Research & Engineering Laboratory
    Associated volumes
    Call number: ZSP-202-263
    In: Research report
    Description / Table of Contents: CONTENTS: Preface. - Abstract. - Introduction. - Theoretical background. - Experimental apparatus and procedures. - Results and discussion. - Conclusions. - Literature cited.
    Description / Table of Contents: The transition in the mode of heat transfer from conduction to convection in a layer of water formed continuously by melting ice from below has been determined experimentally. This was accomplished by locating the inflection point on the curve relating the water-ice interface (or melting front) and time. Thus, the critical Rayleigh number, Rac, at which convective heat transfer started can be correlated empirically as a function of warm plate temperature, Ts, by Rac= 14,200 exp(-6.64 x 10^-2 Ts). This relation is valid for Ts varying from 7.72 to 25.50°C. The initial ice temperature T0 was varied from -4.8 to -22.00°C. The effect of T0 was found to be insignificant. Homogeneous, bubble-free ice was prepared and used in all the experiments.
    Type of Medium: Series available for loan
    Pages: iv, 12 Seiten , Illustrations
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 263
    Language: English
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  • 2
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    Series available for loan
    Hanover, NH : U.S. Army Materiel Command, Terrestrial Sciences Center, Cold Regions Research & Engineering Laboratory
    Associated volumes
    Call number: ZSP-202-256
    In: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command, 256
    Description / Table of Contents: The flow of a compressible fluid through a deep layer of a porous medium with non-uniform permeability was analyzed. The volumetric behavior of the fluid was described first by the perfect gas law, then by the van der Waal's equation of state. Darcy's law was assumed to be valid. For illustration, the model of air flowing through a deep bed of naturally compacted snow was used to carry out numerical computation. The permeability of snow was considered as a function of depth. The nonlinear partial differential equation obtained by combining the continuity equation with Darcy's law was solved by finite difference technique. A time dependent exponential decay boundary condition was used which included the step-rise constant boundary condition as a limiting case. Pressure distributions in the porous medium calculated from the assumption of ideal gas and van der Waal's gas were compared. The data were presented in dimensionless variables.
    Type of Medium: Series available for loan
    Pages: iv, 13 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 256
    Language: English
    Note: CONTENTS: Preface. - Abstract. - Introduction. - Theory. - Computation and results. - Conclusions. - Literature cited.
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  • 3
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    Series available for loan
    Hanover, NH : Corps of Engineers, U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-202-335
    In: Research report
    Description / Table of Contents: CONTENTS: Abstract. - Preface. - Ňomenclature. - Introduction. - Experimental apparatus and procedure. - Testspecimens. - Bubble frequency and velocity. - Analysis of experimental results. - Discussion. - Summary. - Literature cited.
    Description / Table of Contents: An experimental study of the heat transfer characteristics of a bubble-driven water jet on an ice surface was conducted. Two Lucite columns, one 1.829 m high and 0.286 m in diameter and the other 1.219 m high and 0.140 m in diameter were used. Water levels were maintained at 0.762 and 1.524 m in the large column and 0.840 m in the small column. Hypodermic needles with openings of 0.152, 0.406 and 0.838 mm were used for bubble formation. The air flow rate was varied from 7.39 X 10^-8 to 9.91 X I0^-7 m^3/s. In all, 171 experimental runs were conducted. The results can be correlated by Nu = 0.1735 (Rei)^0.848 with a correlation coefficient of 0.84, in which Nu is defined in terms of average heat transfer coefficient h, sample diameter Ds, and thermal conductivity of water kw. Rei is defined in terms of diameter of the impinging water jet at the ice surface, Di, the centerline arrival water velocity vc and the kinematic viscosity of water uw.
    Type of Medium: Series available for loan
    Pages: vi, 16 S. : graph. Darst.
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 335
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  • 4
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    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-77/32
    In: CRREL Report, 77-32
    Description / Table of Contents: An experimental study of forced convective heat transfer over a vertical melting plate has been conducted. This study covers water velocities ranging from 1.7 to 9.8 mm/s and bulk water temperatures from 1.11 to 7.50 C. The experimental results are correlated in terms of Nusselt, Prandtl and Reynolds numbers with a moderate correlation coefficient of 0.843. The results are expected to be useful in predicting the heat transfer characteristics of a much larger prototype ice-water heat sink.
    Type of Medium: Series available for loan
    Pages: v, 12 Seiten , Illustrationen
    Series Statement: CRREL Report 77-32
    Language: English
    Note: CONTENTS Abstract Preface Nomenclature Summary Introduction Problem General review of the subject Experimental apparatus General considerations Water reservoir Test chamber assembly Pumping system Electrical control system Experimental procedure Experimental results Discussion and comparison of results Conclusions Literature cited
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  • 5
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    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-76/12
    In: CRREL Report, 76-12
    Description / Table of Contents: The heat transfer processes associated with melting and refreezing a drill hole 500 m in depth and 0.150 m in initial radius through an ice shelf were approximately analyzed. The results were expressed in graphical form showing the time available for experimentation under the hole as a function of heating duration and heating strength. It was found that the refreezing of the drill hole had a much slower rate than the melting of the hole.
    Type of Medium: Series available for loan
    Pages: vi, 15 Seiten , Illustrationen
    Series Statement: CRREL Report 76-12
    Language: English
    Note: Contents Abstract Preface Summary Nomenclature Introduction Analysis Melting period Freezing period Calculation Conclusion Literature cited Appendix A: Justification of using eq 8 for the calculation of heat transfer coefficient h
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  • 6
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    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-87/22
    In: CRREL Report, 87-22
    Description / Table of Contents: This review discusses problems associated with the anomalous temperature-density relations of water. It covers a) onset of convection, b) temperature structure and natural convective heat transfer, and c) laminar forced convective heat transfer in the water/ice system. The onset of convection in a water/ice system was found to dependent on thermal boundary conditions, not a constant value as in the classical fluids that have a monotonic temperature-density relationship. The water/ice system also exhibits a unique temperature distribution in the melt layer immediately after the critical Rayleigh number is exceeded and soon after it establishes a more or less constant temperature region progressively deepening as the melt layer grows. The constant temperature is approximately 3.2°C for water layers formed from above but varies for melt layers from below. The heat flux across the water/ice interface was found to be a weak power function and to increase linearly with temperature for melted layers from above and below, respectively.
    Type of Medium: Series available for loan
    Pages: vi, 43 Seiten , Illustrationen
    Series Statement: CRREL Report 87-22
    Language: English
    Note: CONTENTS Abstract Preface Nomenclature Introduction Analytical studies on the onset of convection in a horizontal water layer Experimental studies on the onset of convection in a circular horizontal melt layer Temperature structure and heat transfer In a horizontal layer In a circular horizontal melt layer pHeat transfer studies in nonplanar geometries Forced convective heat transfer over a melting surface Discussion and conclusions Onset of convection Temperature structure and natural convective heat transfer Laminar forced convective heat transfer Literature cited
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  • 7
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    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-202-103
    In: Research report / Cold Regions Research and Engineering Laboratory, 103
    Description / Table of Contents: Summary: The effect of air flow on the thermal conductivity of snow was investigated. Steady-state temperature measurements were made along the edge and axis of a cylindrical bed of snow to determine the effective axial thermal conductivity of snow. Unconsolidated snow samples were used, with densities ranging from 0.376 to 0.472 g/cm^3 and corresponding snow particle sizes of 0.065 to 0.219 cm nominal diameter; the mass flow rates employed ranged from approximately 10-40 x 10^-4g/cm^2 sec. Snow density and sample size apparently have opposite effects on the effective thermal conductivity because of the flow of fluid in snow. The test apparatus is described in detail and is illustrated. The results of the experiments are tabulated, and a least square equation is given which represents the results well.
    Type of Medium: Series available for loan
    Pages: iv, 14, A2 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 103
    Language: English
    Note: CONTENTS Preface Summary Introduction Theory Apparatus and experimental procedure Results and discussion References Appendix A: Sample calculations of a and ke
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  • 8
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    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-202-106
    In: Research report / Cold Regions Research and Engineering Laboratory, 106
    Description / Table of Contents: From the Preface: This paper presents a method for determining the extent of heat transfer due to vapor transfer in snow with air flowing through it, which could be useful in connection with studies concerning the changes of physical and mechanical properties of a snow cover caused by temperature gradients and wind currents.
    Type of Medium: Series available for loan
    Pages: iv, 8, A2, B2, C4 Seiten , Illustrationen
    Series Statement: Research report / Cold Regions Research and Engineering Laboratory 106
    Language: English
    Note: CONTENTS Summary Introduction Theory Experimental apparatus apd procedures Results and discussion References Appendix A: Evaluation of d^2Ps/dx^2, dps/dx Appendix B: Sample calculations of β0, β, and De Appendix C: Experimental results and calculated data
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  • 9
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    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-82/5
    In: CRREL Report, 82-5
    Description / Table of Contents: The problem of simultaneous heat and mass transfer in a homogeneous snow layer, with one side kept at its initial temperature and the other side with a step temperature increase, was solved for the case of constant through-flow conditions. An experimentally determined effective thermal conductivity function, i.e. Ke = 0.0014 + 0.58 G (where G is dry mass flow rate of air in g/sq cm-s), was employed in the solution. The computed nondimensional temperature distribution agreed quite well with experimental data taken under pseudo-steady state conditions with the exception of the temperature for the lowest flow rate used in the experiment. The pronounced nonlinearity of the temperature distribution was found to be a strong function of the flow rate. For sinusoidal variation of atmospheric pressure, the responding flow in the snow medium was also found to be sinusoidal. In conjunction with the diurnal temperature change, this variation facilitated the process of repeated sublimation and condensation in alternate directions and thereby produced a surface layer of approximately constant snow density.
    Type of Medium: Series available for loan
    Pages: v, 10 Seiten , Illustrationen
    Series Statement: CRREL Report 82-5
    Language: English
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  • 10
    Series available for loan
    Series available for loan
    Hanover, NH : U.S. Army Cold Regions Research and Engineering Laboratory
    Associated volumes
    Call number: ZSP-201-87/19
    In: CRREL Report, 87-19
    Description / Table of Contents: The approximate heat balance integral method (HBIM) is extended to the case of a medium with variable properties such as snow. The case of linear variation of thermal conductivity was investigated. An alternative heat balance integral method (AHBIM) was developed. Both constant surface temperature and surface heat flux were considered. A comparison was made of the temperature distribution from the HBIM, AHBIM and an analytical method for the case of constant surface temperature. In general, results agree quite well with the analytical method for small values of dimensionless time τ, but the difference becomes more pronounced as τ increases. It was found that the AHBIM with a quadratic temperature profile gave a somewhat better result, especially when the value of the dimensionless distance η is small. For a specific property function of E(η) = eη, closed form solutions were obtained. The results, when compared with those from HBIM, AHBIM and the analytical method were found to agree exceptionally well with the analytical method, especially for large values of τ.
    Type of Medium: Series available for loan
    Pages: iv, 26 Seiten , Illustrationen
    Series Statement: CRREL Report 87-19
    Language: English
    Note: CONTENTS Abstract Preface Nomenclature Introduction Mathematical analysis Constant surface temperature Constant surface heat flux Comparison with exact solution Alternative method Conclusions and comments Literature cited Appendix A: Derivation of equation 25 Appendix B: Derivations of equations 37 and 40 Appendix C: Derivation of equations 37a and 40
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