ELECTRIC AND CHEMICAL CALIBRATION IN FLOW CALORIMETRY

F. Socorro, M. Rodríguez de Rivera

Abstract

The TAM 2277-204 injection calorimeter by Thermometric is used nowadays for the determination of enthalpies of liquid mixtures. A good calibration of the device permits to obtain accurate thermal measures and advance in the knowledge of the energetic processes that are developed in the calorimeter. We identify the system with transfer functions of two poles; the parameters of the TF are determined through a non-linear least-square fit based on Marquardt´s method. Within the identification process we observe that the first time-constant and the sensitivity depend on <i>&rho;</i> <i>c</i>_p <i>f</i> (<i>&rho;</i> is the density, <i>c</i>_p is the heat capacity and <i>f</i> is the flow rate of the injected liquid). We also observe differences between the sensitivity obtained from the electrical calibration and the sensitivity obtained from chemical calibration for the same values of <i>&rho;</i> <i>c</i>_p <i>f</i>; these differences are produced by the fact that the mixture and the electrical dissipation do not occur in the same place. To suppose that the poles of the TF only depend on <i>&rho;</i> <i>c</i>_p <i>f</i> and not on the dissipation place permits to accomplish a complete identification and to evaluate the dissipated power in the mixture as function of the time.

Keywords

thermal measurement, conduction calorimetry, flow calorimetry, liquid mixtures, modelling, signal processing

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IMEKO-WC-2000-TC12-P319.pdf

DOI

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IMEKO TC

TC12 - Temperature and Thermal Measurements

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