A Hot-Wire Method Based Thermal Conductivity Measurement Apparatus for Teaching Purposes

Autor/inn/en	Alvarado, S.; Marin, E.; Juarez, A. G.; Calderon, A.; Ivanov, R.
Titel	A Hot-Wire Method Based Thermal Conductivity Measurement Apparatus for Teaching Purposes
Quelle	In: European Journal of Physics, 33 (2012) 4, S.897-906 (10 Seiten) PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	0143-0807
DOI	10.1088/0143-0807/33/4/897
Schlagwörter	Physics; Computer Uses in Education; Measurement Techniques; Data Processing; Science Laboratories; Heat; College Science; Thermodynamics; Undergraduate Study; Engineering; Energy; Educational Technology + Suchen Sie Ihr Suchwort? Physik; Computernutzung; Messtechnik; Datenverarbeitung; Hitze; Thermodynamik; Grundstudium; Maschinenbau; Energie; Unterrichtsmedien
Abstract	The implementation of an automated system based on the hot-wire technique is described for the measurement of the thermal conductivity of liquids using equipment easily available in modern physics laboratories at high schools and universities (basically a precision current source and a voltage meter, a data acquisition card, a personal computer and a high purity platinum wire). The wire, which is immersed in the investigated sample, is heated by passing a constant electrical current through it, and its temperature evolution, "[delta]T", is measured as a function of time, "t", for several values of the current. A straightforward methodology is then used for data processing in order to obtain the liquid thermal conductivity. The start point is the well known linear relationship between "[delta]T" and ln("t") predicted for long heating times by a model based on a solution of the heat conduction equation for an infinite lineal heat source embedded in an infinite medium into which heat is conducted without convective and radiative heat losses. A criterion is used to verify that the selected linear region is the one that matches the conditions imposed by the theoretical model. As a consequence the method involves least-squares fits in linear, semi-logarithmic (semi-log) and log-log graphs, so that it becomes attractive not only to teach about heat transfer and thermal properties measurement techniques, but also as a good exercise for students of undergraduate courses of physics and engineering learning about these kinds of mathematical functional relationships between variables. The functionality of the experiment was demonstrated by measuring the thermal conductivity in samples of liquids with well known thermal properties. (Contains 1 table and 3 figures.) (As Provided).
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Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2017/4/10