Performance Analysis of Absorption Chillers Using Data Reconciliation

Performance data obtained from measurements of process variables usually do not obey material and energy conservation laws. This is why a data reconciliation process, that is, the adjustment of measured data to obey the conservation laws and other constraints is necessary in order to characterize the real performance of equipment, processes, or the whole plant. The information on the partial load and off-design operation performance of absorption chillers is scarce. Real operation of these units do not always coincides with the expected performance according to the data provided by the manufacturer due to site specific conditions. On the other hand the data reconciliation procedure has been extensively applied mainly only for open cycles with a moderate number of recycle streams. The objective of this work is the development and application of the data reconciliation technique to analyse the performance of absorption chillers using rigorous thermodynamic properties for the calculation of the P-V-T equilibrium properties and enthalpies. We present in this paper the preliminary test results for one of the absorption chiller components, the evaporator. NOMENCLATURE COP, absorption chiller coefficient of performance Cp, specific heat capacity at constant pressure (kJ/kg-K) h, specific enthalpy (kJ/kg) m, mass flow rate (kg/s) P, pressure (kPa) q, vapor quality Q, heat duty (kW) T, absolute temperature (K) t, temperature (oC) x, ammonia mass fraction w, ammonia mole fraction Subscripts a, absorber c, condenser cw, chilled water e, evaporator g, generator in, mass or energy flow entering a component l, liquid phase out, mass or energy flow exiting a component ps, poor (in ammonia) solution r, rectifier rs, rich (in ammonia) solution to, thermal oil v, vapor phase 0, reference value Superscripts L, liquid phase V, vapour phase INTRODUCTION During recent years the interest on absorption chillers to