High-Performance Round & Flat Heat Pipes Advanced Thermal Solutions (ATS) High-Performance Round and Flat Heat Pipes are used to transfer heat with minimal temperature difference or to spread heat across a surface. These heat pipes are low profile, lightweight, and attach easily to a heat sink. Heat pipes are self-driven, two-phase devices. At the hot end (evaporator) the liquid evaporates and turns to vapor. This vapor flows to the cold end (condenser) where it is liquified. The liquid is driven back from the cold end to the hot end by capillary forces within the heat pipe's wick structure. These heat pipes are available with grooved or sintered copper powder wick structures. ATS High-Performance Round and Flat Heat Pipes are widely used in aerospace applications, military devices, temperature control systems, and personal computers.