A single-screw polymer extruder can be thought of as a pump anda heating device for plastic pellets. A certain extrusion setup hasthe following characteristics:
• Polymer: Polyethylene with density 0.95 g/cm3, specific heat1800 J/kgK
• Flow characteristics: polymer temperature increases from 25 Cto 200 C, flow rate 10 kg/hr, extruded strand is a cylinder, 2 mmin diameter
• Heating elements: multiple electric heater bands availablewith 110 Volt, 2 Amp rating
• You measure a back pressure of 300 MPa and a torque of 100 N mat 100 rpm.
Using the energy and mass balances, answer the following aboutthis extruder:
a. What is the linear velocity of the strand exiting thedie?
b. What is the rate of shaft work required to run the screw?
c. How many heater bands are required to heat the polymer to therequired melt temperature?
