# GZ

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References in periodicals archive ?
This value is not needed for the calculation of the elongational heating, but was used for the evaluation of the flow regime by the Graetz number. It is also shown in Table 4.
Graetz numbers in the die at different flow rates Volume flow rate ([cm.sup.3] [s.sup.-1] Graetz number 6.63 682 11.04 1136 15.46 1590 17.67 1818 22.09 2272 TABLE 4.
The average Graetz number [Gz.sub.AV] for the first stage can be evaluated by integrating
Figure 4 shows this entrance correction ratio for the mean Nusselt number versus Graetz number. For example, [DELTA]Nu/Nu is less than 1% for [lambda] > 0.25, [lambda] > 0.4, and [lambda] > 1.0 for parallel surface, circular tube, and corrugated flow channels, respectively.
Graetz number below 1 indicates that conduction is dominant.
At screw speeds of 20-40 rpm, Graetz number increased above 1 with a ratio of Griffiths:Graetz of ~0.5.
Extruder screw Flow rate Wall shear Corrected shear speed (rpm) ([m.sup.3]/s) rate ([s.sup.-1]) viscosity (Pa s) 10 3.30 E -06 29.8 2000 20 6.70 E -06 60.4 1230 30 9.70 E -06 87.5 990 40 1.30 E -05 117.3 840 50 1.60 E -05 144.3 740 60 1.90 E -05 171.4 655 70 2.30 E -05 207.5 560 80 2.60 E -05 234.5 515 90 3.00 E -05 270.6 490 100 3.30 E -05 297.7 460 Extruder screw speed (rpm) Graetz number (Gz) Griffiths number (G) Ratio (G/Gz) 10 0.9 0.27 0.29 20 1.83 0.65 0.36 30 2.64 1.18 1.45 40 3.53 1.78 0.50 50 4.42 2.45 0.55 60 5.3 3.12 0.59 70 6.23 3.64 0.58 80 7.21 4.37 0.61 90 8.12 5.26 0.65 100 8.94 6.10 0.68
To calculate the Graetz number; the thermal diffusivity of the blend is required.
While this method is discussed later, the data is presented in the figures where the flexural modulus is compared to the Graetz number. This method of presentation should indicate if the modulus is dependent on the mold temperature.
The relationship between the flexural modulus and the Graetz number for plaques of 1.0 mm thickness is shown in Fig.
The physical properties and operating conditions are the same as those of the previous case, except that the inlet flow rate [Q.sub.o] is now 50 kg/h, and the corresponding Graetz number Gz is 154.4; the Peclet number Pe is 1252.
here [Gz.sup.*] represents a modified Graetz number and is defined as
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