Experimental Determination of Thermal Conductivity of Cortical Bone With Heat Loss Estimation

2018 ◽  
Author(s):  
JuEun Lee ◽  
Seon Jeong Huh ◽  
Hee Joon Lee
Keyword(s):  
Thermal Conductivity ◽  
Reference Material ◽  
Cortical Bone ◽  
Heat Loss ◽  
Experimental Measurement ◽  
Experimental Apparatus ◽  
Order Of Magnitude ◽  
Temperature Offset ◽  
Numerical Program

This paper presents an experimental measurement of the thermal conductivity of bovine cortical bone by an improved parallel plate method to increase the accuracy of the measurement. An experimental apparatus was designed to measure the thermal conductivity of the cortical bone using a reference material with a known thermal conductivity by the heat transfer through the samples. To improve the measurement accuracy, a reference material was selected as quartz, which is of the same order of magnitude of the thermal conductivity of bovine cortical bone reported in the existing literature. Additionally, the temperatures at the heat source and heat sink were set to ±5°C from the ambient temperature to reduce the inevitable heat loss in the measurement. The temperature offset was determined numerically. The current experimental measurement was validated by an in-house finite-difference numerical program. The heat loss in the measurement was predicted from the numerical program. The thermal conductivity of the bovine cortical bone was then determined to be 0.55 ± 0.02 W/mK with compensating heat loss.

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

Determination Of Thermal Conductivity Of Soils: A Need For Computing Heat Loss Through Buried Submarine Pipelines

1979 ◽  
Author(s):  
P.C. Rawat ◽  
S.L. Agarwal ◽  
A.A. Malhotra ◽  
S.K. Gulhati ◽  
G.V. Rao
Keyword(s):  
Thermal Conductivity ◽  
Heat Loss

scholarly journals On the magnetic shielding of large spaces, and its experimental measurement

1916 ◽  
Vol 92 (644) ◽  
pp. 529-549 ◽  
Keyword(s):  
Magnetic Field ◽  
Experimental Determination ◽  
Recent Work ◽  
Experimental Measurement ◽  
Magnetic Shielding ◽  
Small Space ◽  
The Earth ◽  
Order Of Magnitude ◽  
The Subject

It is not a matter of difficulty to annul almost completely the field of the earth throughout a small space by a suitable choice of an iron shield. If, however, the region over which the field must be reduced is large, the problem becomes more difficult unless considerable masses of iron are used. For it is evident that the absolute dimensions of the shield are not important to the degree of shielding produced, that is to say, that a given shield magnified in all its parts in the same ratio continues to give the same degree of shielding. The object of the present investigation is to show that the shielding of large spaces can nevertheless be achieved by the employment of properly designed multiple or concentric shields, without the necessity for a prohibitive amount of iron. In connection with some recent work, moreover, the necessity has arisen for maintaining a magnetic field at least as small as 5·10 -3 within a region of comparatively large dimensions. It is evident that the most suitable means is to reduce the field of the earth to this extent, but calculations soon show that the usual arrangements of soft iron shields involve a prohibitive amount of material. The necessity in fact arises for the determination of the most economical arrangement capable of giving a specified high shielding ratio. Since, in view of applications of the work, the actual magnitude of the field must be known, corrected for every variety of magnetic leakage which can invalidate the theory, some experimental device is also required for the measurement of such fields. There is apparently no record of the experimental determination directly of fields even of this order of magnitude, and since a method has been found which is capable of considerable accuracy and is in fact suitable for the measurement of fields only 10 -4 times that of the earth, a description of this and of other methods with their practical limitations appears to be of value. It must be emphasised that the difficulties which are encountered, and the methods necessary to overcome them, are to a great extent peculiar and inevitable to work which must be carried on with large quantities of material. The investigation which originally led to the necessity for known fields of such a small order—it has since been supplemented by others which cannot at present be described—was the subject of earlier communications by one of us.

Development of a method for multielemental determination in water by EDXRF with radioisotopic source of 238Pu.

2019 ◽  
Vol 7 (2A) ◽  
Author(s):  
Camilo Fuentes Serrano ◽  
Juan Reinaldo Estevez Alvares ◽  
Alfredo Montero Alvarez ◽  
Ivan Pupo Gonzales ◽  
Zahily Herrero Fernandez ◽  
...  
Keyword(s):  
Thin Layer ◽  
Expanded Uncertainty ◽  
Considerable Decrease ◽  
X Ray ◽  
Precipitation Efficiency ◽  
Method Of Determination ◽  
Sensitivity Curves ◽  
Order Of Magnitude ◽  
Metrological Parameters

A method for determination of Cr, Fe, Co, Ni, Cu, Zn, Hg and Pb in waters by Energy Dispersive X Ray Fluorescence (EDXRF) was implemented, using a radioisotopic source of 238Pu. For previous concentration was employed a procedure including a coprecipitation step with ammonium pyrrolidinedithiocarbamate (APDC) as quelant agent, the separation of the phases by filtration, the measurement of filter by EDXRF and quantification by a thin layer absolute method. Sensitivity curves for K and L lines were obtained respectively. The sensitivity for most elements was greater by an order of magnitude in the case of measurement with a source of 238Pu instead of 109Cd, which means a considerable decrease in measurement times. The influence of the concentration in the precipitation efficiency was evaluated for each element. In all cases the recoveries are close to 100%, for this reason it can be affirmed that the method of determination of the studied elements is quantitative. Metrological parameters of the method such as trueness, precision, detection limit and uncertainty were calculated. A procedure to calculate the uncertainty of the method was elaborated; the most significant source of uncertainty for the thin layer EDXRF method is associated with the determination of instrumental sensitivities. The error associated with the determination, expressed as expanded uncertainty (in %), varied from 15.4% for low element concentrations (2.5-5 μg/L) to 5.4% for the higher concentration range (20-25 μg/L).

HOT WIRE METHOD FOR DETERMINATION OF THE THERMAL CONDUCTIVITY OF SUGAR CANE FIBERS

2020 ◽  
Author(s):  
Marcelo Borges dos Santos ◽  
CLAUDIA BITTENCOURT ◽  
Ana Carolina Mendonça Mansur ◽  
Luís Mauro Moura ◽  
Carlos Augusto Castro Ferreira
Keyword(s):  
Thermal Conductivity ◽  
Sugar Cane ◽  
Hot Wire ◽  
Wire Method
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