A device measuring the difference between the incoming fluid flow temperature and the temperature of artificially heated fluid (see Fig. 1).

Fig. 1. Thermoanemometer sensor schematic .

Mathematical Model

The temperature difference is related to thermal properties of fluid ( $\begin{array}{l}\{ \lambda, \, a, \, \nu\}\end{array}$ ) and flow velocity $\begin{array}{l}u\end{array}$ :

(1)	$\begin{array}{l}\displaystyle \Delta T = \frac{q \, r}{\lambda}\frac{1}{\rm Nu}\end{array}$

The calibration plot is usually set in $\begin{array}{l}\displaystyle \left \{ \frac{1}{\Delta T}, \, {\rm Nu} \right \}\end{array}$ coordinates or in cae of a small velocity range in $\begin{array}{l}\displaystyle \left \{ \frac{1}{\Delta T}, \, u \right \}\end{array}$ coordinates.

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Mathematical Model

See also