Samsung first introduced a heatpipe design for smartphone with the Galaxy S7. Apparently, that design will find its way to the new Galaxy S8. According to sources, Samsung first wanted to implement a two-pipe design, but further on decided to stick with the tried and tested setup.
Back when the Galaxy S7 was made, it featured the thinnest hear pipe on the market. However, Samsung will break new records with the new design that are developing with its partners. It will be just 0.4mm thick. That pipe will be responsible for taking the heat of the chipset and transferring it on the back. There is a graphite sheet which will help disperse the heat more efficiently.