scholarly journals IV. The absolute thermal conductivities of copper and iron

1893 ◽  
Vol 53 (321-325) ◽  
pp. 151-153 ◽  
Keyword(s):  
Thermo Electric ◽  
Different Temperatures ◽  
The Absolute ◽  
Thermal Conductivities

The experiments described in the paper were undertaken with the object of determining the theoretical conductivity at different temperatures of iron, and, in particular, of pure electrolytically deposited copper. The method adopted was that due to Forbes, with two modifications. ( a .) The thermo-electric method of determining temperature was employed.

scholarly journals X. The absolute thermal conductivities of iron and copper

1893 ◽  
Vol 184 ◽  
pp. 569-590 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Experimental Work ◽  
University College ◽  
Different Temperatures ◽  
The Absolute ◽  
Thermal Conductivities

The experiments described in this paper were undertaken at the suggestion of Pro­fessor A. Gray, M. A., University College, Bangor, with the object of contributing something to the results still necessary to establish the experimental work bearing on the absolute thermal conductivity of metals on a more satisfactory basis. They were also intended to furnish a determination of the absolute conductivity of pure copper at different temperatures. The data already accumulated on the thermal conductivities of iron and copper are due chiefly to Ångström, Forbes, Neumann, Tait and Mitchell, and more recently to Kirchhoff and Hansemann and Lorenz.

scholarly journals Thermal Conductivities of Choline Chloride-Based Deep Eutectic Solvents and Their Mixtures with Water: Measurement and Estimation

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3816
Author(s):  
Taleb H. Ibrahim ◽  
Muhammad A. Sabri ◽  
Nabil Abdel Jabbar ◽  
Paul Nancarrow ◽  
Farouq S. Mjalli ◽  
...  
Keyword(s):  
Atmospheric Pressure ◽  
Choline Chloride ◽  
Deep Eutectic Solvents ◽  
Standard Uncertainty ◽  
Heat Transfer Fluids ◽  
Wide Range ◽  
Different Temperatures ◽  
Experimental Values ◽  
Water Measurement ◽  
Thermal Conductivities

The thermal conductivities of selected deep eutectic solvents (DESs) were determined using the modified transient plane source (MTPS) method over the temperature range from 295 K to 363 K at atmospheric pressure. The results were found to range from 0.198 W·m−1·K−1 to 0.250 W·m−1·K−1. Various empirical and thermodynamic correlations present in literature, including the group contribution method and mixing correlations, were used to model the thermal conductivities of these DES at different temperatures. The predictions of these correlations were compared and consolidated with the reported experimental values. In addition, the thermal conductivities of DES mixtures with water over a wide range of compositions at 298 K and atmospheric pressure were measured. The standard uncertainty in thermal conductivity was estimated to be less than ± 0.001 W·m−1·K−1 and ± 0.05 K in temperature. The results indicated that DES have significant potential for use as heat transfer fluids.

scholarly journals I. On the absolute expansion of mercury

1912 ◽  
Vol 211 (471-483) ◽  
pp. 1-32 ◽  
Keyword(s):  
Hydrostatic Method ◽  
Physical Problems ◽  
Glass Bulb ◽  
Different Temperatures ◽  
The Mean ◽  
The Absolute ◽  
Made In

The determination of the expansion of mercury by the absolute or hydrostatic method of balancing two vertical columns maintained at different temperatures does not appear to have been seriously attempted since the time of Regnault (‘Mém. de l’Acad. Roy. des Sci. de l’Institut de France,' tome I., Paris, 1847). His results, though doubtless as perfect as the methods and apparatus available in his time would permit, left a much greater margin of uncertainty than is admissible at the present time in many cases to which they have been applied. The order of uncertainty may be illustrated by comparing the value of the fundamental coefficient of expansion (the mean coefficient between 0° and 100°C.) given by Regnault himself, with the values since deduced from his observations by Wüllner and by Broch. They are as follows:— Regnault . . . . . . 0·00018153. Wüllner . . . . . . 0·00018253. Broch . . . . . . . 0·00018216. The discrepancy amounts to 1 in 180 even at this temperature, and would be equivalent to an uncertainty of about 4 per cent, in the expansion of a glass bulb determined with mercury by the weight thermometer method. The uncertainty of the mean coefficient is naturally greater at higher temperatures. If, in place of the mean coefficient, we take the actual coefficient at any temperature, the various reductions of Regnault’s work are still more discordant, and the rate of variation of the coefficient with temperature, which is nearly as important as the value of the mean coefficient itself in certain physical problems, becomes so uncertain that the discrepancies often exceed the value of the correction sought. It is only fair to Regnault to say that these discrepancies arise to some extent from the various assumptions made in reducing his results, and are not altogether inherent in the observations themselves.

scholarly journals The dielectric coefficients of gases.— Part I. The rare gases and hydrogen

1931 ◽  
Vol 132 (820) ◽  
pp. 569-585 ◽  
Keyword(s):  
Great Difficulty ◽  
Relative Accuracy ◽  
Rare Gases ◽  
Electric Moment ◽  
Different Temperatures ◽  
The Absolute

The heterodyne beat method affords a means of measuring the dielectric coefficients of gases with a relative accuracy exceeding that of any of the older determinations, and in consequence it has been employed by a number of observers during recent years. The published results, however, in many cases, refer mainly to the method, and measurements are restricted to one or two gases apparently selected at random. Such determinations when made at different temperatures suffice to determine the electric moment, but owing to the great difficulty of measuring the absolute values, the figures for the dielectric coefficients themselves obtained by different observers cannot be co-ordinated.

3. Physical Proof that the Geometric Mean of any Number of Quantities is less than the Arithmetic Mean

1869 ◽  
Vol 6 ◽  
pp. 309-309
Author(s):  
Tait
Keyword(s):  
Specific Heat ◽  
Geometric Mean ◽  
Arithmetic Mean ◽  
Absolute Zero ◽  
Present Problem ◽  
Unequal Distribution ◽  
Different Temperatures ◽  
The Absolute ◽  
The Masses

If a number of equal masses of the same material be given, at different temperatures, and enclosed in an envelope impervious to heat, they will finally assume a common temperature; which is the arithmetic mean of the initial temperatures, if the material be one whose specific heat does not vary with temperature.But they may be brought to a common temperature by means of reversible thermodynamic engines employed to obtain the utmost amount of work from the initial unequal distribution. This question was first investigated by Thomson (Phil. Mag. 1853, “On the Restoration of Energy from an unequally heated Space”), and the application of his method to the present problem shows that the final common temperature of the masses, when as much work as possible has been obtained from them, is the geometric mean of the initial temperatures; but this investigation introduces the condition that the temperatures must be measured from the absolute zero.

scholarly journals Die Temperaturabhängigkeit der Wärmeleitfähigkeiten von gasförmigem Normal- und Ortho-Deuterium bei Temperaturen des flüssigen Wasserstoffes

1967 ◽  
Vol 22 (10) ◽  
pp. 1528-1531
Author(s):  
W. Uebelhack ◽  
W. Eichenauer ◽  
K. Heinzinger ◽  
A. Klemm
Keyword(s):  
Relative Difference ◽  
Different Temperatures ◽  
Thermal Conductivities

The relative difference of the thermal conductivities of gaseous ortho- and normal-deuterium has been measured at three different temperatures 18,5°K, 19,8°K and 21,1°K. The results are 0,97 ·10-3, 1,08 ·10-3 and 1,45 ·10-3 respectively, with an accuracy of ±10%. They are compared with the relative difference of the viscosities for the two deuterium modifications. This comparison leads to a difference in ƒtr and ƒint for ortho- and normal-deuterium in the EUCKEN relation.

scholarly journals The thermal conductivities of oxygen and nitrogen

1928 ◽  
Vol 118 (780) ◽  
pp. 594-607 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Temperature Coefficient ◽  
Thermal Conduction ◽  
Standard Substance ◽  
The Absolute ◽  
Thermal Conductivities

The interest in the determination of the thermal conductivities of oxygen and nitrogen lies partly in their relation to the thermal conductivity of air. The latter is the medium which practically every experimenter on gaseous thermal conduction has investigated, and has therefore become the standard substance in this field of research. Being a mixture chiefly of the gases oxygen and nitrogen, with the latter in the greater proportion, the value of its conductivity should lie between those of oxygen and nitrogen and should be nearer that of nitrogen than that of oxygen. The authors, in common with Weber and Todd, have verified this experimentally, the only observer finding these con­ductivities in a contrary order being Winkelman, who used a cooling thermometer method. The following is a table of the results hitherto obtained for the absolute thermal conductivities at 0° C. of oxygen and nitrogen, together with their authors’ results for air. The values marked with an asterisk have been deduced by applying the temperature coefficient, 0.0029 per 0° C., to results which were obtained at temperatures above 0° C. Weber has recently published a new result for the thermal conductivity of air, 0.0000574, which is about 1 per cent. higher than his old value. Assuming that, if his results for oxygen and nitrogen were revised, they would be increased in the same proportion, his new values for these gases would be—oxygen 0.0000583, and nitrogen 0.0000572.

scholarly journals III. Approximate determinations of the heating-powers of arcturus and a Lyræ

1870 ◽  
Vol 18 (114-122) ◽  
pp. 159-165 ◽  
Keyword(s):  
Zero Point ◽  
Absolute Magnitude ◽  
The State ◽  
Heating Power ◽  
Thermo Electric ◽  
The Absolute

About twelve months ago I began to make observations upon the heating-power of the stars. My first arrangements were simply these: I made use of a delicate reflecting astatic galvanometer, and a thermo-electric pile of nine elements. The pile was screwed into the tube of a negative eye­piece of the Greenwich Great Equatoreal, from which the eye-lenses had been removed. I soon convinced myself that the heat, condensed by the object-glass of twelve and three-quarters inches upon my pile, was appreciable in the case of several of the brighter stars; but the endless changes in the zero-point of the galvanometer-needle, and the magnitude of these changes, compared with those arising from the heating-power of the stars, prevented me from making any attempts to estimate the absolute magnitude of the effects produced. Every change in the state of the sky, every formation or dis­sipation of cloud, completely drove the needle to the stops.

scholarly journals Thermal transpiration of a dissociating gas

1940 ◽  
Vol 175 (963) ◽  
pp. 474-483 ◽  
Keyword(s):  
Approximate Solution ◽  
Steady State ◽  
Absolute Magnitude ◽  
Mass Action ◽  
Law Of Mass Action ◽  
Thermodynamical Equilibrium ◽  
Thermal Transpiration ◽  
Different Temperatures ◽  
The Absolute ◽  
Narrow Opening

In this paper the thermal transpiration of a dissociating gas has been investigated theoretically for two chambers maintained at different temperatures and communicating with each other through a narrow opening. It has been shown that the condition of thermodynamical equilibrium and the usual transpiration relation for each constituent cannot both be satisfied simultaneously. In § 2 the problem has been treated rigorously from the viewpoint of a steady state. Expressions have been worked out showing how the law of mass action suffers modification in this case. Expressions have also been deduced for the atomic and molecular concentrations in the two chambers and the modified transpiration relation is stated. In § 3 an approximate solution of the problem has been given which is based on the assumption of thermodynamical equilibrium in each chamber. Expressions have been deduced for the absolute magnitude as well as the ratio of the atomic or molecular concentrations in the two chambers in the general case and some limiting cases. Finally, the relative merits and demerits of both the treatments have been clearly set forth.

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