With the growing human civilization, the energy demand is constantly rising which has been accomplished by extracting energy from various sources. However the energy management is a tedious task and has often lead to supply and demand mismatch. Energy storage bridges the gap between energy supply and demand while also improving energy system efficiency and performance. Thermal energy storage (TES) has attracted growing interest around the world in recent decades. In the present study, numerical experiments have been performed to investigate the melting of phase change material (PCM) in a rectangular enclosure with different heat source conditions and PCM chamber orientation. The value of inclination angle is considered as 15°, 30°, 45°, 60°, 75° and 90° with the horizontal plane. A rectangular enclosure of length (L) 0.12 m and height (H) 0.05 m filled with Lauric acid is used for the analysis. In the present study effect of constant temperature and sinusoidal temperature heating with and without the effect of inclination angle is analyzed. With the increase in inclination angle the melting rate decreases. At higher inclination angles the melting rate can be improve if we change the heating condition to sinusoidal temperature heating from the constant temperature heating.