Thermal diffusivity measurements by Ångström's method in a fluid environment

• Ångström's method has been used for measuring the thermal diffusivity, a, and the radial heat loss coefficients of a thin constantan wire, both in a vacuum and with the wire immersed in air and in four different liquids, and using temperature wave periods of 1 to 1000 s. The presence of a surrounding fluid medium causes errors of up to 90% in the measured values of a. It is shown that both the experimental errors and the radial heat loss coefficients can be accurately calculated using simple models, both at high and at low frequencies, and that a previously developed two-frequency model can be used to obtain accurate data for a even under these conditions, provided the frequency is high enough. We also present a new variety of Ångström's model, valid only at very low frequencies and with purely convective heat loss.

Subject headings

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Keyword

Thermal diffusivity

high pressure

fluid medium

heat loss

experimental methods

Ångström's method

Condensed matter physics

Kondenserade materiens fysik

fysik

Physics

Publication and Content Type

ref (subject category)

art (subject category)