HANSER Hanser Publishers, Munich • Hanser Gardner Publications ...
HANSER Hanser Publishers, Munich • Hanser Gardner Publications ...
HANSER Hanser Publishers, Munich • Hanser Gardner Publications ...
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Solution<br />
Heating power Nn:<br />
Mass flow rate of the plastic m :<br />
As the area of the heating element is small compared to that of the sheet the equation<br />
applies [14]<br />
total area of the heating element Ag = 2 <strong>•</strong> A so that we have<br />
T<br />
= 9.95<br />
100<br />
T = 995 K<br />
3.7 Dielectric Heating<br />
The dielectric heat loss that occurs in materials of low electrical conductivity when placed<br />
in an electric field alternating at high frequency is used in bonding operations, for example,<br />
to heat-seal plastic sheets or films.<br />
The power dissipated in the polymer is given by [14]<br />
where<br />
Nn= power (W)<br />
/ = frequency of the alternating field (s" 1 )<br />
C = capacitance of the polymer (farads)<br />
E = applied voltage (Volt)<br />
0 = phase angle<br />
(3.69)