New method for COP optimization in water- and air-cooled single and double effect LiBr–water absorption machines

In this work a new method to optimize the COP in water- and air-cooled single and double effect LiBr/H2O absorption chillers is proposed. This method determines the effect of condensation temperatures and the solution concentration variation on COP, clearly defining the crystallization limit for different scenarios. This limit is especially important in the design of air-cooled chillers. Taking this into account a simulation program has been developed to calculate the optimum COP. In the case of parallel flow double effect chillers this program estimates not only the optimum COP but also the percentage of refrigerant vapour generated in the high and low temperature desorbers in terms of the condensation temperature. Additionally it provides the mass flow of the solution that should be distributed to each desorber to attain the desired variation in solution concentration.