In the absorber of most absorption refrigeration systems, aqueous solution of LiBr at high concentration is sprinkled on the horizontal tube-bank cooled by cooling water. In this case, heat and mass transfers occur simultaneously. However, to make the systems more compact, a concept of spraying-type absorber can be considered. In this type, the processes of heat and mass transfers can be separated into two steps. That is, the strong solution of LiBr-$H_2O$ is subcooled below the equilibrium condition through a small heat exchanger, and then sprayed into the environment of the refrigerant vapor for absorption.
In the present study, a series of the experiments have been performed to examine the heat and mass transfer characteristics of a LiBr-$H_2O$ spray within a spraying-type absorber. Effects of the absorber pressure and the flow rate and the inlet temperature and concentration of the LiBr aqueous solution were investigated. The experimental results show that the absorption performance is improved with the increases of the inlet concentration of LiBr-$H_2O$ and the absorber pressure, and with the decrease of the inlet temperature. Also, the maximum absorption rate is limited by the thermodynamic equilibrium condition. An analysis has been performed based on the simplified drop absorption model and compared with the experimental results. The analytical results underpredict the absorption performance. This implies that the region near the nozzle exit, where the simplified model doesn't apply, has dominant contribution to the absorption performance. At 170d(d : nozzle exit orifice diameter) downstream of the atomizer, the absorption (about 90% of the maximum absorption) is almost completed, and the absorption downstream of this point is rather insignificant.
