Investigation On Integrated Heat Sink With Heat Pipes

With the increase in integral density and performance and the decrease in size for CPU, heat flux is critically high. But the conventional solution of forced-air convection heat transfer is trending to its limit due to a confined space in the PC and heat dissipation of CPU has become one main restrict factor in the development of CPU and an important issue to investigate in the field of hydrodynamics and heat transfer. As a two-phase heat transfer device, heat pipe can transport a considerate quantity of heat with a very small temperature difference from evaporation section to condensing section, so heat pipe is widely applied to the field of high heat flux due to its intrinsic merits such as superior conductivity, surface temperature uniformity, high efficiency of heat transfer and compact and adaptable structure, ect. Phase change heat-transfer devices such as heat sink with heat pipe and heat sink of vapor chamber have developed to cooling CPU.A concept of integrated heat sink with heat pipes is presented to meet the demand of high dissipation power on the basic of an integrated introduction of investigation and development for heat dissipation technologies, vapor chamber and conventional heat sinks with heat pipes for cooling CPU in the paper. The operating principle of heat pipe is also introduced briefly. According to the working condition of CPU, an experimental system is established to test heat transfer performance of integrated heat sink with heat pipes including thermal resistance and surface temperature uniformity. Comparing the experimental results for different working conditions of heat dissipation power, air velocities and inclination angles is to determine the surface temperature variety of CPU.The method of CFD numerical simulation is employed to replace experimental investigation. Hence, STAR-CD of the commercial software is used to simulate the outer flow field and heat transfer performance of integrated heat sink with heat pipes cooled by airflow. It is found that simulated results agree with experimental results well, which indicates that simulation method is reasonable and reliable. Further, simulated computations for different fin thickness, fin pitches and air velocities are performed to analyze their effects on heat transfer performance of heat sink. Finally, a new optimized structure of integrated heat sink with heat pipes is provided to meet future demands for cooling CPU and its heat transfer is also evaluated. For multi-heat source and higher dissipation power of electronic devices, the integrated heat sink with heat pipes attatched fins stagged in different positions of channels is presented and its flow and temperature fields are alsosimulated to enhance heat transfer. As a conclusion, all mentioned above are useful for the design of heat sink with excellent efficiency of heat dissipation and further research.