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Journal of Refrigeration, Air conditioning, Heating and ventilation

VACUUM ASSISTED ABSORPTION CHILLER. PART I: MODELING AND SIMULATION

  1. Carlos Armenta-Deu

Abstract

A new absorption chiller assisted by a vacuum device has been simulated and characterized through a simulation process. Simulation has been developed for a range of 0.75-10 bars for the evaporation process with a constant ratio between the condensation and evaporation pressure of 10. Simulation has predicted a great improvement of the COP of the absorption chiller when operating at evaporation pressures under atmospheric level, with values of 6.844 for a moderate vacuum of 0.1 bar. Simulated COP evolution follows a potential law within 97.6% accuracy, thus allowing the user to predict the real COP at a large pressure interval. The results of the simulation have shown that for a single stage configuration, the ammonia/water chiller works better than the equivalent system of water/lithium-bromide when operating at low pressure and temperature at the evaporator, with a relative gain of 26%. The simulated configuration for a two stage configuration has also revealed a relative gain of 15.4% compared to the water/lithium-bromide system. The simulation process predicts that below 0.35 bar for the evaporation process, the absorption chiller shows higher COP than a compression system.

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