Latent heat storage systems using phase change materials (PCMs) store large amounts of thermal energy at a near-constant temperature in a compact space. However, PCMs possess relatively low thermal conductivity which prolongs their phase change process; consequently, their applications have been limited. To address this, a numerical investigation was conducted in this study on the heat transfer mechanism in a horizontal shell and multi-finned tube heat exchanger. Erythritol (melting point of 117 degrees C) was selected as the PCM and Therminol-55 was used as the heat transfer fluid. ANSYS Fluent v. 19.0 was used to numerically solve the governing equations. Once validated by comparing with exper-imental data, the developed numerical model was then used to investigate the effect of several design parameters regarding tubes and fins on the storage performance. It was found that number of tubes, fin height as well as rotation of fins and tubes significantly influence the melting process. Overall, the melting duration could be decreased by about 44% when the number of tubes increased from 5 to 9. Moreover, the melting time could be decreased by about 31% when the fin height increased from 6 to 15 mm (C) 2020 Elsevier Ltd. All rights reserved.