Flat Loop Heat Pipe with Bi-Transport Loops for Graphics Card Cooling

A flat loop heat pipe (FLHP) with bi-transport loops is developed for the cooling of graphics card with high heat flux up to 80W/cm(2). The evaporator and the pipes are made of copper and ultrapure water (electronic resistivity > 18M-cm) as the working fluid. To give the loop heat pipe (LHP) better performance, the evaporator is made in a flat shape to reduce the contact resistance between the evaporator and the chip. The advances of the LHP with bi-transport loops are discussed. The heat transfer performance is tested with different filling rate in different orientations. The test results show that the LHP can start up easily and can transport large amount of heat stably. The orientation of the condenser above the evaporator gives a better performance, and filling with 13g of water gives a better performance. Limited by the evaporator temperature lower than 90 degrees C, the LHP can transport 320W when the evaporator is above the condenser and 380W when the condenser is above the evaporator.