COP optimisation of a triple-effect H2O/LiBr absorption cycle under off-design conditions

It is desirable for absorption chillers to attain the highest COP possible when working under design conditions. If these conditions change during a working day, the control variables must be readjusted in order to attain the optimal COP. This work shows the COP optimisation of a triple-effect parallel-flow H2O/LiBr absorption chiller under design and off-design conditions. Computer simulations are conducted for different evaporation and condensation temperatures, considering the same value for the change in solution concentration (Delta x) in all generators. These simulations estimate not only the optimum COP as a function of the outlet HTG solution temperature, but also the solution mass-flow rates to be pumped to each generator in order to attain that optimum. For temperatures of 142 degrees C to 227 degrees C, the optimal COP ranged from 1.05 to 2.13, and the solution mass flow rates range pumped to LTG, MTG, HTG were 2.1-22.1 kg/h, 2.2-23.8 kg/h, and 2.9-44.6 kg/h per kW of cooling capacity, respectively. These results are useful for optimising a triple-effect absorption chiller driven by solar energy. (C) 2016 Elsevier Ltd. All rights reserved.

COP optimisation of a triple-effect H2O/LiBr absorption cycle under off-design conditions Articles