Temperature Increase Calculation Example for a Screw Pump

3 Temperature Increase Calculation Example for a Screw Pump 

Experiments were run on a laboratory screw pump to evaluate the fluid temperature increase of an enclosed fluid as a function of element rotation time. For this case, the device was similar to that shown in Fig. 7.4, and the discharge was blocked using a valve. The blocked flow caused the rate to be zero and = 0 p. Both the device and the fluid were at room temperature at the start of each experiment. The task at hand is to use the information below and the equations presented in Chapter 7 to calculate the temperature increase for the fluid for a total time of 30 seconds in three-second increments. The dimensions of the single-flighted extrusion device are provided in Table 7.5. 

The viscosity for the Newtonian polypropylene glycol fluid used for the experiments was measured and then modeled using Eq. 7.90. The temperature response of this fluid was very similar to the polypropylene glycol fluid shown in Fig. 7.31 except that this fluid was considerably more viscous. The density and heat capacity were 1015 kg/m and 2000 J/(kg °C), respectively. 

The screw pump was operated at a screw speed of 85 rpm (N = 1.417 revolu-tions/s). The calculated results are shown in Table 7.6, which was generated using the method found earlier in this chapter and in Appendix A7. 

The discharge of the screw is ciosed by the vaive, Q a = Qmp, which ieads to the foi-iowing pressure gradient term in the device using Eq. 1.28  

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