Design and Simulation of the CPU Fan and Heat Sinks

Traditional design methods to achieve improvement in heat sink performance are not suitable for meeting new thermal challenges. Revolutionary rather than evolutionary concepts are required for removing heat from the electronic components. We have recently developed an emerging novel approach, the integration design of the forced convection air cooling system. The aerodynamic design for the miniature axial-flow fan is conducted and a CPU fan is designed to be integrated with the radial fins in order to form a complete fan-heat sink assembly. The 3-D data of the fan generated by FORTRAN program are imported into Pro/E to create its 3-D model. The performance curve of the fan prototype fabricated by the computer numerically controlled machine is tested in a standard wind tunnel. To reduce the economic cost and prompt the design efficiency, the computational fluid dynamics is adopted to estimate the initial fan´s performance. A series of radial heat sinks is designed in accordance with the outflow angle of airflow discharged from the fan. The inlet angle of the fin is arranged so that the incoming flow from the upstream impeller matches the fin´s angle of heat sinks. Using the multi-block hexahedral grid technique, the numerical simulation of the system, including the fan and heat sinks, is performed by means of Multiple Reference Frame (MRF) and RNG k-epsiv Model. Our results indicate that the thermal resistance of the streamlined heat sink is decreased by 15.9% compared to the traditional heat sink and the entropy generation rate of the streamlined heat sink is lower. The experiments support our simulation results. The series of heat sinks is able to achieve the productive thermal performance when the integration design concept is utilized.