On-line indirect measures estimation for the performance of an absorption heat transformer integrated to a water purification process

In order to optimize the operating performance and the long term performance of an absorption heat transformer integrated to a water purification process, a thermodynamic and corrosion model with an on-line data acquisition system (with developed programs in bash and Octave computing languages) were used. These models are assisted by direct measurements of the outlet temperatures of the four components of the absorber heat transformer (absorber, AB; generator, GE; evaporator, EV; and condenser, CO), two calculated pressure levels (AB–EV and GE–CO) and two calculated concentrations (AB and GE) of the working mixture LiBr–H2O for the thermodynamic model, and of the Electrochemical Potential and Electrochemical Current, for the corrosion model. As associated variables of these models (on-line indirect measures) are the coefficient of performance (COP), the corrosion current density (Icorr), the electrochemical noise resistance (Rn), and the localization index (LI). Since the process contains noisy and stochastic variables, a Kalman filter is used to predict COP. The results of on-line indirect measurements estimation are similar to the out-line steady estimations, which are a useful reference to reduce operating and investment costs and to implement an operating strategy, or to test new configurations.