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 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.

Determination of Thermal Conductivity of Soils: A Need for Computing Heat Loss Through Buried Submarine Pipelines

1982 ◽  
Vol 22 (04) ◽  
pp. 558-562 ◽  
Author(s):  
P.C. Rawat ◽  
S.L. Agarwal
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Crude Oil ◽  
Rheological Properties ◽  
Heat Loss ◽  
Experimental Results ◽  
Dry Density ◽  
Empirical Relationships ◽  
Thermal Conductivities

Abstract An important parameter required for computing heat loss through buried submarine pipelines transporting crude oil is the thermal conductivity of soils. This paper describes an apparatus designed for determination of the thermal conductivity of soils at the desired moisture/ density condition in the laboratory under steady-state conditions. Experimental results on the three soils studied show that thermal conductivity increases as dry density increases at a constant moisture content and that it increases as water content increases at constant dry density. These results confirm the trends isolated earlier by Kersten. The experimental results are compared with the available empirical relationships. Kersten's relation is observed to predict the thermal conductivity of these soils reasonably. The predictions from Makowski and Mochlinski's relation (quoted by Szilas) are not good but improve if the sum of silt and clay fractions is treated as a clay fraction in the computation. Introduction Submarine pipelines are used extensively for transporting crude oil from offshore to other pipelines offshore or onshore. These pipelines usually are steel pipes covered with a coating of concrete. They often are buried some depth below the mudline. The rheological properties of different crude oils vary, and their viscosities increase with a decrease in temperature. Below some temperature, the liquid oil tends to gel. Therefore, for efficient transportation, the crude must be at a relatively high temperature so that it has a low viscosity. The temperature of the soil/water system surrounding a submarine pipeline is usually lower than that of oil. This temperature difference induces heat to flow from the oil to the environment, and the temperature of the oil decreases as it travels along the length of the pipeline. One must ensure that this temperature reduction does not exceed desirable limits dictated by the rheological properties of oil and by the imperatives of efficient economic properties of oil and by the imperatives of efficient economic transportation. Thus the analytical problem is to predict the temperature of crude in the pipeline some distance away from the input station. To do so, knowledge of the overall heat transfer coefficient for the pipeline is required, for which, in turn, it is necessary to know the thermal conductivities of the oil, the pipeline materials and its coating, and the soil. This paper presents thermal conductivities of soils determined in the laboratory under steady-state conditions and also presents a comparison of the test results of three soils with values determined from existing empirical relationships. Literature Review Heat moves spontaneously from higher to lower temperatures. In a completely dry porous body, transmission of heat can take place not only by conduction through the solid framework of the body and the air in the pores but also by convection and radiation between the walls of a pore and by macro- and microdistillation. In soils, however, it can be ascribed essentially to conduction, a molecular phenomenon that can be expressed in terms of experimentally determined coefficients of conductivity or resistivity, although these actually may include microdistillation and other mechanisms. SPEJ p. 558

XXX.—Thermal and Electric Conductivity

1878 ◽  
Vol 28 (3) ◽  
pp. 717-740 ◽  
Author(s):  
Tait
Keyword(s):  
Thermal Conductivity ◽  
Electric Conductivity ◽  
Marked Effect ◽  
Original Method ◽  
The State ◽  
British Association ◽  
Pure Metals ◽  
The Absolute

The following paper contains the results of an inquiry which has occupied me at intervals for somewhere about ten years. It was carried out in part at the expense of the British Association, and I have already reported results to that body in 1869 and 1871. But these provisional reports referred to very short ranges of temperature only, and the experiments were made with faulty thermometers, for which I had not the corrections which had been carefully determined by Welsh at Kew.The inquiry arose from my desire to extend to other metals the very beautiful and original method which Principal Forbes devised, and which the state of his health prevented him from applying to any substance but iron. Forbes' experiments gave a result so very remarkable, and (as it seemed to me) so theoretically suggestive, that I wished to extend them to other pure metals, and also, in one or two cases at least, to alloys.I believe that Principal Forbes had at least two reasons for undertaking his investigations:—(1.) When he commenced his inquiry, there was no really accurate or trustworthy determination of the absolute conductivity of any body whatever for heat. (2.) FORBES had himself, in 1833 and subsequent years, pointed out a very remarkable analogy between the conducting powers of metals for electricity and for heat, and had shown that these were almost precisely proportional to one another—that is to say, that the list of the average relative conductivities of different metals for electricity differed, from that of their relative conductivities with regard to heat, certainly not more than did the several electric lists furnished by different experimenters, and certainly less than the corresponding thermal lists. Hence it was natural to suppose that temperature might have a marked effect on thermal conductivity, as it was known to have such an effect on electric conductivity.

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 Experimental determination of the thermal conductivities of gases

1926 ◽  
Vol 110 (753) ◽  
pp. 91-122 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Specific Heat ◽  
Experimental Determination ◽  
Dynamic Theory ◽  
Great Accuracy ◽  
Constant Volume ◽  
Order Of Accuracy ◽  
Molecular Collision ◽  
Thermal Conductivities

The analysis of the dynamic theory of gases has indicated an interesting relation between the viscosity η , the thermal conductivity K, and the specific heat at constant volume C c of a gas. This relation is represented by the expression K = f . C c . η , in which the factor f depends upon the law of force operative in molecular collision, and is known if K, C c , and η can be determined experimentally. In view of its importance in this respect, and also from the fact that great accuracy and consistency of measurement are possible in modern determinations of the viscosity of gases, the importance of the development of a method by which the conductivity can be measured with the same order of accuracy demands increasing attention.

scholarly journals The thermal conductivity of carbon dioxide

1927 ◽  
Vol 114 (767) ◽  
pp. 354-366 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Free Path ◽  
Critical Pressure ◽  
Mean Free Path ◽  
Double System ◽  
Wire Method ◽  
The Mean ◽  
The Absolute ◽  
The Many

Of the many experimental determinations of the thermal conductivity of Co 2 which have been made, the absolute values given by the various observers vary from 3·07 × 10 -5 cal. sec. -1 cm. -1 deg. -1 (Winkelman, 1), to 3·39 × 10 -5 cal. sec. -1 cm. -1 deg. -1 (Weber, 2), and generally speaking the experiments were modifications of two principal methods, namely, the electrically heated wire of Schleimacher (3) and the cooling thermometer method. In both of these methods convection losses were present to a degree depending on the dimensions and disposition of the apparatus, and on the pressure of the gas; therefore, in the author’s opinion, the discrepancies amongst various observers are due to the practice of attempting to eliminate these convective losses by diminishing the pressure. Such a procedure is justifiable only if the reduction of pressure is not carried beyond the point at which the mean free path of the molecules becomes comparable with the dimensions of the containing vessel. This is a critical point in the determination of the conductivity of a gas, as the authors’ experiments on Co 2 indicate that the convection becomes negligible only at pressures for which the mean Free Path Effect is such that the significance imposed on the conductivity by Fourier’s law loses its meaning, and below this critical pressure the conductivity varies with the pressure in a manner depending on the dimensions of the vessel containing the gas. In the experiments of Gregory and Archer (4), on the thermal conductivities of air and hydrogen, the use of a double system of electrically-heated wires enabled the authors accurately to identify the critical pressure at which convective losses became negligible. This is an extremely important point in all applications of the hot-wire method to the absolute determination of the conductivities of gases, and alone justifies the procedure of lowering the pressure to eliminate convective losses. Above this critical pressure it is necessary to disentangle the conduction and convection losses, and below, the meaning of conduction loses its ordinary significance.

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 DETERMINATION OF THERMAL CONDUCTIVITY FOR ADOBE (CLAY SOIL) MIXED WITH DIFFERENT PROPORTIONS OF QUARTZ (SHARP SAND)

2019 ◽  
Vol 7 (3) ◽  
pp. 335-345
Author(s):  
S. K Singh ◽  
Ngaram S. M. ◽  
Wante H. P.
Keyword(s):  
Thermal Conductivity ◽  
Correlation Coefficient ◽  
Building Materials ◽  
Clay Soil ◽  
Building Construction ◽  
Average Correlation ◽  
Thermal Insulator ◽  
Materials Used ◽  
Thermal Conductivities

This research investigated the thermal conductivity of Adobe mixed with Quartz in view of their availability usage as building materials. The thermal conductivities of disc made from Adobe-Quartz chippings were determined. The values of the thermal conductivities obtained were between 0.6Wm-1k-1and 0.9Wm-1k-1, these values could be used to identify Adobe/Quartz as one of the engineering materials used in building construction. Adobe/Quartz was prepared in discs form of the same diameters and thicknesses and was also compressed under the same pressure of 15 atmospheres (100: 0, 95: 5and 80: 20). The average values of the thermal conductivities were between 0.07Wm-1Ҡ-1 and 0.93Wm-1Ҡ-1, for sample contained the proportion of (80:20) and the sample of ratio (95:5). MATLAB 7.0 and EXCEL software were used in the various computations, especially in determining dT/dt, Root mean square error (RMSE), Curve fittings parameter and the correlation coefficient, R2. An average correlation coefficient of 0.78 was existed between Adobe-Quartz ratio and thermal conductivity. The equation, y = -0.11x2 + 0.01x + 1.03 is the general equation that can be used for the prediction of average thermal conductivity at various ratios. Where y is the average thermal conductivity and x here signifies the ratios. This also indicates that compacted Adobe-Quartz of low density will be a suitable thermal insulator when used as aggregates in walls.

Heat Flow Calorimetry

2008 ◽  
Author(s):  
José A. Martinho Simões ◽  
Manuel Minas da Piedade
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Flow ◽  
Heat Sink ◽  
Reaction Vessel ◽  
Heat Output ◽  
Large Numbers ◽  
Different Temperatures

Heat flow calorimeters, also known as “heat flux,” “heat conduction,” or “heat leakage” calorimeters, are instruments where the heat output or input associated with a given phenomenon is transferred between a reaction vessel and a heat sink. This heat transfer can be monitored with high thermal conductivity thermopiles containing large numbers of identical thermocouple junctions regularly arranged around the reaction vessel (the cell) and connecting its outside wall to the heat sink (the thermostat). The determination of the heat flow relies on the so-called Seebeck effect. An electric potential, known as thermoelectric force and represented by E, is observed when two wires of different metals are joined at both ends and these junctions are subjected to different temperatures, T1 and T2. Several thermocouples can be associated, forming a thermopile. For small temperature differences, the thermoelectric force generated by the thermopile is proportional to T1 − T2 and to the number of thermocouples of the pile (n): E = nε ′ (T1 − T2) (9.1) where ε′ is the thermoelectric power of a single thermocouple (ε′ = dE/dT).

scholarly journals Effects of temperature and pressure on the thermal conductivities of solids. Part I. The effect of temperature on the thermal conductivities of some electrical insulators

1905 ◽  
Vol 204 (372-386) ◽  
pp. 433-466 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Experimental Work ◽  
Effect Of Temperature ◽  
Opposite Conclusion ◽  
Effects Of Temperature ◽  
Temperature And Pressure ◽  
Thermal Conductivities

The question as to whether the thermal conductivity of a solid varies with temperature is an important one, and a considerable amount of attention has been bestowed on it. The experimental work which has been done cannot, however, be said to have led to a definite conclusion, owing to the discrepancies between the results obtained by different observers. Although the more recent of these results have produced a general disbelief of the idea which prevailed a few years ago, that the thermal conductivity of a solid would increase as the temperature increased, yet they do not justify the opposite conclusion being drawn.

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