Flow modeling of continuous Indian unleavened flat bread (chapatis) former

A mathematical model was developed to predict the flow rate and torque requ irements in continuous Indian unleavened flat bread (chapatis) forming syst em, based on mechanical extrusion. Variables included were screw speed, len gth to die width, and product moisture. Flow rate and torque were effected by product moisture and die width. For a constant pressure drop, flow rate increased as die width and product moisture increased. The flow rate and torque equations used for modeling were: Q = G(1)NF(dt)(1-delta /H) + G(2)F(pt)/mu (P-1-P-2)/L(1+f) and tau = G(3)N(G(4)mu + G(5)mu (delta)) + G(6)(P-2 - P-1), respectively wh ere Q is the volumetric flow rate, tau the torque input, N the screw speed, F-dt the total drag flow, F-pt the total pressure flow, delta the flight c learance, H the channel depth, mu viscosity of dough in the channel, mu (de lta) viscosity in the flight clearance, P-1 dough pressure at input end, P- 2 dough pressure at output end, L the length of extrusion section under stu dy in axial direction, f correction for pressure flow and G(1)-G(6) are the constants. (C) 2001 Elsevier Science Ltd. All rights reserved.