This paper presents experimental results of an air-PCM heat exchanger, with an in-line arrangement of cylindrical containers. The objective is to highlight the physical phenomena occurring in a single container during the phase change. Temperature and airflow measures were carried out. These values were used to find the heat exchanges on the container. The experimental heat values were compared and validated with the theoretical heat stored obtained from the material properties. An only conduction 1D radial model is proposed to describe the melting front in the container.Keywords: phase change materials, thermal storage unit, cylinder, latent heat, radial conduction.