SIMULTANEOUS ESTIMATION OF FLUID THERMAL-CONDUCTIVITY AND HEAT-CAPACITY IN LAMINAR DUCT FLOW

An inverse analysis is applied to identify simultaneously the constant thermal conductivity k and heat capacity C of the fluid in laminar fo rced convection inside a circular duct from the knowledge of transient temperature measurements taken at a single location in the downstream region. Transient temperatures are generated by suddenly applying a c onstant wall heat flux over a finite length of the duct at the inlet r egion. The iterative algorithm of Levenberg-Marquardt method is used t o solve the resulting system of algebraic equations in the minimizatio n procedure. The effects of sensor location both in the axial and radi al directions, heated length of the duct, magnitude of applied wall he at flux, the number of measurements, and errors involved in the measur ed data on the accuracy of estimations are studied. Copyright (C) 1996 Published by Elsevier Science Ltd