Heat transfer. An aluminum cylinder is heated over a propane Bunsen burner (left frame). The chemical energy released by burning propane gets transferred to the cylinder. Its thermal energy is increased as a result. The heated cylinder is then immersed into a beaker with water (right frame). Thermal energy of the cylinder is then transferred to water whose thermal energy is increased. This is manifested by water's temperature increase from 24.8 C to 31.0 C, as measured by a digital thermometer.