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 liminar forced 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 constant wall heat flux over a finite length of the duct at the inlet region. The iterative algorithm of Levenberg-Marquardt method is used to solve the resulting system of algebraic equations in the minimization procedure. The effects of sensor location both in the axial and radial directions, heated length of the duct, magnitude of applied wall heat flux, the number of measurements, and errors involved in the measured data on the accuracy of estimations are studied.