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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Table 3.1 Coefficients of Heat Penetration of Mold Material and Resin [8]<br />
Material<br />
Beryllium copper (BeCu 25)<br />
Unalloyed steel (C45W3)<br />
Chromium steel (X40Crl3)<br />
Polyethylene (HDPE)<br />
Polystyrene (PS)<br />
The approximate values for steel are<br />
A =50W/(m-K)<br />
p =7850kg/m 3<br />
c = 0.485 kj/(kg <strong>•</strong> K)<br />
The coefficient of heat penetration b<br />
3.3 Heat Conduction with Dissipation<br />
The power created by the tangential forces in the control volume of the fluid flow is<br />
denoted as dissipation [9]. In shear flow the rate of energy dissipation per unit volume is<br />
equal to the product of shear force and shear rate [ 10]. The power due to dissipation [11]<br />
therefore is:<br />
From the power law we get<br />
For a Newtonian fluid with n - 1 we obtain<br />
Coefficient of heat penetration b<br />
Ws 05 Hi 2 KT 1<br />
17.2 <strong>•</strong> 10 3<br />
13.8 <strong>•</strong> 10 3<br />
11.7- 10 3<br />
0.99 <strong>•</strong> 10 3<br />
0.57 <strong>•</strong> 10 3<br />
(3.46)<br />
(3.47)<br />
(3.48)<br />
The applicable differential equation for a melt flow between two plates, where the upper<br />
plate is moving with a velocity Ux (Figure 2.4) and the lower plate is stationary [11] is<br />
(3.49)