This paper presents a numerical and experimental study of absorption phenomenon in ammonia-water absorption chiller which is a very promising technology in the solar cooling field. The purpose of the research is to analyse the coupled heat and mass transfers that take place in a plate heat exchanger used as absorber in order to identify limiting transfers. For this purpose, a numerical modeling of a falling film absorber has been performed. Then, an experimental study has been carried out on a test bench in order to experiment the absorber in real operating conditions and to validate the numerical model. So, experimental and numerical results are compared to discuss hypothesis of the model and analyse the global behaviour of the absorber. Moreover, local phenomena are discussed thanks to the numerical study.