To explore the possibility of using solid-liquid phase-change cooling for periodically or intermittently operated electronic equipment, details of an experimental study of time-dependent melting heat transfer in a rectangular enclosure with three discrete protruding heat sources is presented. A series of experimental measurements in an enclosure with phase-change materials (PCM) of n-octadecane heated by three discrete protruding heat sources at a constant rate on one of vertical wall is described The opposite wall of the enclosure is cooled at a constant temperature, and all other walls of the enclosure are insulted. The time-dependent solid-liquid shapes of the interface during the melting process, the variation of surface temperature and Nusselt number of the heat sources, and the effects of subcooling are investigated.. An empirical correlation predicting the relationship between the liquid-phase fraction and subcooling is given.