Analysis of the Thermal/Mechanical Energy in Food Extrusion Process

식품 압출성형공정의 열 및 기계에너지 분석

  • Chung, Moon-Young (Department of Food Science and Technology, Dongguk University) ;
  • Lee, Seung-Ju (Department of Food Science and Technology, Dongguk University)
  • Published : 1997.02.01

Abstract

The energy supplied by motor of extruder, being known mostly to be dissipated as heat, was classified into two kinds of energy: a thermal energy by heat dissipation and a purely mechanical energy. The thermal energy was defined as a energy in terms of temperature rise and the mechanical energy as the motor energy minus the heat dissipated energy. A method to derive the thermal energy and the relative mechanical energy (the mechanical energy calculated regarding the mechanical energy at the lowest screw speed as zero) under the condition of constant barrel temperature was developed by which an extrusion case was analyzed. When extruding com grits with moisture $(27{\sim}37%)$ at low barrel temperature $({\leq}80^{\circ}C)$, the thermal energy slightly increased with increase in the moisture content, whereas the relative mechanical energy increased to a great extent. When increasing the screw speed, the thermal energy was nearly kept constant, whereas the relative mechanical energy largely varied. It is concluded that as the moisture content increases, the role of the mechanical energy becomes more effective than the heat energy dissipated from the motor energy.

Keywords

extrusion;thermal energy;mechanical energy;heat dissipation