May

8

Numerical data for microwave water heater

For a WR 340 heat transfer of height $b$ with a liquid slab of thickness $e$ , $\beta$ or $be/\beta$ is the physical constant which governs the microwave water heating process [4], [7] :

$\beta$ = 7.35 $e$ 230 dB.° C/m = 1.690 $e$ dB.° C/mm = 0.194 $e$ °C/mm where $e$ is in mm.

$\frac{be}{\beta}= 222,5 mm^3/ ^oC$

Using experimental data $T_o$ and $\Delta T$ , the value of $z^*$ , $V^*$ and $\Delta z/z^*$ can be deduced through the data given in Figs.1 and 2 in conjunction with the above formulae. $\delta$ is a fraction of the total temperature variation $\Delta T$ .

Fig. 1 Approximate conjugate $\delta$ ratio along the length of the heat tranfer.

For $\delta$ = 0.990 $z^*$ = 4.6 $T_o/2\beta$ $V^*$ = 4.6v = 4.6 $beT_o/2\beta$

For $\delta$ = 0.999 $z^*$ = 6.9 $T_o/2\beta$ $V^*$ = 6.9v = 6.9 $beT_o/2\beta$

Fig. 2 $\delta$ ratio dependence on the relative error.

For $\delta$ = 0.990 $\Delta z/z^*$ = $\Delta V/V^*$ = 0.78 $\Delta T/T_o$

For $\delta$ = 0.999 $\Delta z/z^*$ = $\Delta V/V^*$ = 0.85 $\Delta T/T_o$

$\Delta T$ is related to the process parameters with the formula :

$\Delta T$ °C = 3.79 (KW required)/GPM

Publié par Mahi Microwave Water Heater S'abonner au flux RSS feed

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