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 />
The conversion factors for the units used in the calculation of the dimensionless numbers<br />
below are<br />
F1 = 0.001; F2 = 1000; F3=3600<br />
The Graetz number Gz is calculated from<br />
with G in kg/h and L in mm. Using the values given above, Gz =186.51. The Reynolds<br />
number is obtained from<br />
with Ve in m/s, H* in m and p in g/cm 3 .<br />
Using the values given above, Re = 0.03791.<br />
With H in m and Ve in m/s we get from<br />
and the Brinkman number Br from<br />
Finally, the product Re <strong>•</strong> Pr <strong>•</strong> Br = 7768.06.<br />
5.3.4 Cooling of Melt in Mold<br />
As mentioned in Section 3.2.1, the numerical solution of the Fourier equation, Equation<br />
3.31, is presented here for crystalline and amorphous polymers.<br />
5.3.4.1 Crystalline Polymers<br />
The enthalpy temperature diagram of a crystalline polymer shows that there is a sharp<br />
enthalpy rise in the temperature region where the polymer begins to melt. This is caused<br />
by the latent heat of fusion absorbed by the polymer when it is heated and has to be<br />
taken into account when calculating cooling curves of crystalline polymers.<br />
By defining an equivalent temperature for the latent heat (Figure 5.41), GLOOR [22]<br />
calculated the temperature of a slab using the Fourier equation for the non-steady-state