The Determination of Thermal Diffusivities of Thermal Energy Storage Materials: Part II—Molten Salts Beyond the Melting Point

1969 ◽  
Vol 91 (3) ◽  
pp. 189-197 ◽  
Author(s):  
K. Sreenivasan ◽  
M. Altman
Keyword(s):  
Thermal Diffusivity ◽  
Melting Point ◽  
Sodium Nitrate ◽  
Lithium Fluoride ◽  
Molten Salts ◽  
Liquid Lithium ◽  
Energy Storage Materials ◽  
Flux Measurements ◽  
The Difference ◽  
Thermal Diffusivities

A quasisteady method for measuring the thermal diffusivity of molten salts at temperatures above their melting point is described. Essentially, the difference between the temperature at the surface and at the center of a cylindrical container is measured for a constant rate of surface temperature rise. The liquid, whose thermal diffusivity is to be measured, is contained in a narrow annular groove concentric with the surface. The advantages of this method are: (a) no heat flux measurements are needed; (b) no liquid temperature need be measured; (c) theoretically assumed boundary conditions can be experimentally realized; (d) absence of convection can be experimentally verified. Results of measurements are reported for liquid lithium fluoride and sodium nitrate. The results for sodium nitrate agree with previously published results. The thermal conductivity of lithium fluoride can be empirically expressed in terms of the melting point, the molecular weight and the density, as k=0.9Tm1/2ρm2/3M−7/6

Thermal Diffusivity Measurement of Pure Te, (Hg1−x Cdx)1−yTey and (Hg1−xZnx)1−yTey

1994 ◽  
Vol 299 ◽  
Author(s):  
Hossein Maleki ◽  
Lawrence R. Holland
Keyword(s):  
Thermal Diffusivity ◽  
Melting Point ◽  
Wide Temperature Range ◽  
Laser Flash ◽  
Thermal Diffusivity Measurement ◽  
Temperature Range ◽  
Diffusivity Measurement ◽  
Laser Flash Technique ◽  
Flash Technique ◽  
Thermal Diffusivities

AbstractThe thermal diffusivities of (Hg1−xCdx)1−yTey and (Hg1−xZnx)1−yTeywith 0.55 ≤ y ≤ 1.0 and 0.0125 ≤ x ≤ 0.05465 and of pure Te are measured over a wide temperature range by the laser flash technique. The diffusivity of near pseudobinary Hg1−xCdxTe solids decrease more rapidly with temperature approaching the melting point than pseudobinary solids previously reported. The solid diffusivity for x=0.02817 is 0.83 mm2/s at 371°C, decreasing to 0.22 mm2/s at 614°C. The diffusivity of Te rich (Hg1−xCdx)1−yTey melt increases with x and with temperature. The melt diffusivity for x=0.03934 is 0.91 mm2/s at 485°C, increasing to 4.93 mm2/s at 851°C. For Te rich (Hg1−xZnx)1−yTey melt with x=0.0125 and y=0.7944 there appears to be a minimum diffusivity of about 2.6 mm2/s near 700°C. The thermal diffusivity of pure Te solid is 0.97 mm2/s at 300°C and decreases to 0.64 mm2/s at 439°C. The melt diffusivity is 1.52 mm2/s at 486°C, increasing to 3.48 mm2/s at 584°C.

scholarly journals The Determination of Thermal Diffusivities of Thermal Energy Storage Materials, Part I: Solids up to Melting Point

1967 ◽  
Vol 89 (3) ◽  
pp. 407-414 ◽  
Author(s):  
H. Chang ◽  
M. Altman ◽  
R. Sharma
Keyword(s):  
Energy Storage ◽  
Melting Point ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Energy Storage Materials ◽  
Large Temperature ◽  
Other Substances ◽  
Temperature Ranges ◽  
Thermal Diffusivities

This paper describes a method for the determination of thermal diffusivities which has been developed specifically for substances which are poor conductors and which have high melting points. Materials which are useful for thermal energy storage fall into this category. The method has several unique features. The basic principle involved consists of raising the surface temperature of a solid specimen at a uniform rate. After the initial transients have died out, the diffusivity can be determined from temperature measurements alone. The advantages of the method are: (a) Heat flux measurements are not needed; (b) materials can be tested right up to the melting point, since the specimens can be encapsulated and softening can be tolerated; (c) large temperature ranges can be tested quickly; (d) precision and accuracy are good. The method has been extended to the liquid range, and results will be published as Part II. Results of measurements are reported for alumina and lithium fluoride. The results for alumina (Lucalox) check results reported previously. The results on LiF differ from published results. Data on other substances are still being produced and results will be published at a later date.

Optical Determination of Thermal Conductivity with a Plane Source Technique

1968 ◽  
Vol 23 (1) ◽  
pp. 44-47 ◽  
Author(s):  
Silas E. Gustafsson ◽  
Nils-Olov Halling ◽  
Rolf A. E. Kjellander
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Thermal Diffusivity ◽  
Sodium Nitrate ◽  
Molten Salts ◽  
Potassium Nitrate ◽  
Plane Source ◽  
Melting Points ◽  
Optical Determination

A recently developed plane source method for non-steady-state measurements of the thermal conductivity and thermal diffusivity of transparent liquids is now being applied to the study of molten salts. In these first measurements sodium nitrate and potassium nitrate have been investigated from their melting points to about 450°C. No temperature dependence of the thermal diffusivity can be established for either of the liquids, whereas the thermal conductivity in both cases increases very slowly with the temperature.A description of the experimental arrangement is included.

Preparation and Heat Transfer/Thermal Storage Properties of High-Temperature Molten Nitrate Salts

2015 ◽  
Vol 814 ◽  
pp. 60-64
Author(s):  
Hong Tao Zhang ◽  
You Jing Zhao ◽  
Jing Li Li ◽  
Li Jie Shi ◽  
Min Wang
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Melting Point ◽  
Latent Heat ◽  
Sodium Nitrate ◽  
Molten Salts ◽  
Operating Temperature ◽  
Potassium Nitrate ◽  
Nitrate Salts ◽  
Latent Heat Of Melting

The thermal stability of molten salts, operating temperature range and latent heat of melting for the molten salts at high temperature have been studied in the present investigation. The multi-component molten salts composed of purified potassium nitrate, purified sodium nitrate were prepared by statical mixing method [1]. The stability experiments were carried out at 500 to 600°C, and the experimental result showed that the purified nitrate molten salts performed better high-temperature thermal stability and its optimum operating temperature was increased from 500°C to 550°C. DSC analysis indicated that the purified nitrate molten had a lower melting point and a higher phase change latent heat. The melting point of purified binary nitrate molten salts was sharp decreased to 225.2°C and latent heat of melting for molten salts was also reduced from 78.41J/g to 81.15J/g compared with unpurified nitrate salts. Besides, the change in the concentration of impurities by analyzing in the binary molten salts, and combination of XRD test results can be found that the degree of degradation reduce and improve the thermal efficiency of the storage of binary molten salts by purified sodium nitrate and potassium nitrate.

STUDIES ON THE THERMODYNAMICS AND CONDUCTANCES OF MOLTEN SALTS AND THEIR MIXTURES: PART II. THE VISCOSITIES, HEATS OF FUSION, AND HEAT CAPACITIES OF LITHIUM CHLORATE AND LITHIUM CHLORATE–LITHIUM NITRATE MIXTURES

1964 ◽  
Vol 42 (7) ◽  
pp. 1616-1626 ◽  
Author(s):  
A. N. Campbell ◽  
M. K. Nagarajan
Keyword(s):  
Free Energy ◽  
High Precision ◽  
Molten Salts ◽  
Heat Capacities ◽  
Liquid Lithium ◽  
Lithium Nitrate ◽  
Transition Formula ◽  
Different Temperatures ◽  
Molten Lithium ◽  
The Difference

The viscosities at different temperatures of pure molten lithium chlorate and of mixtures of lithium chlorate with lithium nitrate have been determined with high precision. The heats of fusion, and the molar heat capacities of both solid and liquid lithium chlorate, and of mixtures of lithium chlorate and lithium nitrate have also been determined. The heat of the transition [Formula: see text] has been obtained as the difference between the heats of solution in water of the two forms. The enthalpy, free energy, and entropy of mixing have been derived.

MOLTEN SALTS ELECTRICAL CONDUCTIVITY IN THE SYSTEM SILVER NITRATE–SODIUM NITRATE

1952 ◽  
Vol 30 (12) ◽  
pp. 922-923 ◽  
Author(s):  
June Byrne ◽  
Helen Fleming ◽  
F. E. W. Wetmore
Keyword(s):  
Electrical Conductivity ◽  
Melting Point ◽  
Silver Nitrate ◽  
Mole Fraction ◽  
Sodium Nitrate ◽  
Molten Salts ◽  
Energy Of Activation ◽  
Equivalent Conductivity ◽  
Density Data ◽  
Arrhenius Energy

Conductivity and density data have been obtained for the system silver nitrate – sodium nitrate. The Arrhenius energy of activation for electrical migration in sodium nitrate and in the binary melts decreases with rising temperature above the melting point, as was shown previously for silver nitrate. The equivalent conductivity isotherms for the binary melts are almost linear in the mole fraction.

scholarly journals The Isotope Effect for Electromigration of Sodium Ions in Molten Sodium Nitrate

1972 ◽  
Vol 27 (2) ◽  
pp. 288-293
Author(s):  
Nobufusa Saito ◽  
Katsumi Hirano ◽  
Kohei Okuyama ◽  
Isao Okada
Keyword(s):  
Melting Point ◽  
Isotope Effect ◽  
Sodium Nitrate ◽  
Mass Effect ◽  
Relative Difference ◽  
Internal Mass ◽  
Sodium Ions ◽  
Molten Sodium

AbstractThe relative difference (Δb/b) between the internal electromigration mobilities of 22Na and 24Na in molten NaNO3 has been measured in the range 340 - 515 °C. The internal mass effect, μint= (Δb/b)/(Δm/m) is - 0.056 at 340 °C (melting point 308 °C), - 0.079 at 435 °C and - 0.068 at 515 °C. The errors in μint are ±0.002.

Sign in / Sign up

Export Citation Format

Share Document