New flat-fan sheets adiabatic absorber for direct air-cooled LiBr/H2O absorption machines: Simulation, parametric study and experimental results

A new generation of highly efficient absorbers for direct air-cooled LiBr/H2O absorption machines is presented and discussed in this paper. As distinguishing aspects of these absorbers, it is worth mentioning that they are adiabatic units, which improves the heat and mass transfer; besides, they distribute the solution in flat-fan sheets, which allows for compact absorber designs; lastly, they are directly air-cooled units, which eliminates the need of cooling towers. Additionally, the paper includes the development of a mathematical modeling for analysis and simulation of this kind of absorbers. Based on that model, a parametric study of the proposed absorber design is carried out to optimize its use in a particular air-cooled single–double-effect absorption machine. Simulation outcomes of that specific absorber were compared with some experimental results obtained by using the aforementioned absorption machine as testing facility to validate the model. A good agreement was found between predictions and experimental results for most of the characteristic operation parameters of the absorber. Finally, it was observed that the proposed absorber design enables air-cooled LiBr/H2O absorption machines to work far from crystallization limits even at ambient temperatures around 40 °C.

► A novel direct air-cooled adiabatic absorber with flat-fan sheets is described. ► The absorber design is adequate for single- and double-effect LiBr/H2O chillers. ► The absorber was integrated into a single–double-effect absorption prototype. ► A simulation code for that absorber is developed and experimentally validated. ► The proposed absorber avoids solution crystallization at high ambient temperatures.