Modelling and experimental validation of an in-tube vertical falling film absorber with counter flow arrangement of solution and gas

In the present study, an in-tube vertical falling film absorber with gas and falling film in counter-current flow arrangement, which utilizes NH 3 −H 2 O pair as the working fluid, has been built and is then integrated with a single effect absorption heat pump. Twelve sets of tests have been designed and conducted, taking into account the standard operating range of these types of heat pumps. The results obtained from performing a testing procedure on this experimental setup have been utilized to assess the accuracy of a developed mathematical model in simulating the corresponding absorption phenomenon. The obtained results demonstrate an acceptable agreement between the values simulated by the model and the experimental data, while addressing various heat duties. Furthermore, it has been shown that the transfer coefficients between the liquid film and the interface are order/s of magnitude higher than the ones between the gas and the interface and therefore, the absorption process is controlled by the heat and mass transfer coefficients between the film and the interface. Moreover, it has been revealed that in falling film absorber modelling, insignificant errors in the evaluation of rate of absorption can lead to a notable miscalculation of the absorber size. It is concluded that the effect of hydrodynamic of the film on the heat and mass transfer process should be considered for future enhancement of the model