HEAT-TRANSFER TO AND TRANSPORT-PROPERTIES OF WHEAT GLUTEN IN A TUBULAR REACTOR

The design and modeling of a tubular reactor, similar to an extrusion rheometer, which accounts for reacting flow is described. A numerical study (finite differences) of heat transfer to a flowing and reacting biopolymer melt (wheat gluten), similar to extrusion processing, is de scribed and compared to experimental data. The cylindrical wall is non isothermal in the axial direction, but is adequately characterized by a third-order polynomial determined experimentally. Convective and vis cous dissipation terms are included in the energy equation. The rheolo gical behavior of the melt is described by a power law model, tau = m( o)e ((-E/RT))gamma(n). The consistency coefficient pre-exponential, m( o), is 530,000-2,100,000 Pa-sec(n) and the power law exponent or flow index, n, is 0.38-0.65 for a 25-30% moisture content range and a 110-2 09 C temperature range. The flow index decreases with increasing conve rsion due to polymerization reactions occurring at elevated temperatur es. Flow curves, bulk temperatures, and temperature profiles are prese nted for a variety of cylinder wall temperatures and biopolymer moistu re contents.