Thermal energy storage systems are used to address the power intermittency issues in solar thermal power systems. Researchers have separately studied the use of Latent Heat Storage (LHS) and Sensible Heat Storage (SHS) systems, whereas, the present work focuses on the performance of a combination of LHS and SHS, i.e. a Hybrid Thermal Energy Storage (HTES) system. In this respect, a multi-tube HTES heat exchanger is designed. The PCM (LHS medium) is encapsulated in five cylindrical containers which are surrounded by concrete (SHS medium). A 2D numerical model is developed to study the effect of the number of Heat Transfer Fluid (HTF) tubes on the charging and discharging behaviour of the HTES system, using COMSOL Multiphysics. The HTF tubes are embedded inside the concrete and a constant wall temperature boundary condition is applied at the inner walls of the HTF tubes. Four multi-tube configurations with 6, 10, 15, and 18 HTF tubes are compared for the fixed amount of PCM and concrete. It is observed that by increasing the HTF tubes from 6 to 15, the charging/discharging time is reduced by 57.32%/ 51.90%. However, there is an insignificant reduction by increasing the number of HTF tubes to 18.