Principles of energy balance

The two preceding chapters have dealt with the mass output of the extruder and its relation to screw speed and back pressure, but it has been mentioned that energy considerations impose additional restrictions on the useful output in commercial operations. The purpose of the present chapter is to formulate the energy balance of the single-screw extruder, examine the components of this balance and the factors on which they depend, and deduce the overall effects on the energy balance of deliberate changes in operating conditions. These aspects have been largely neglected in the literature, so their inclusion gives greater relevance of theory to practical experience and permits further rational development of operating strategies.