Design Of Micro Channels With Corrugated Bottom And Investigations On Its Performance Of Heat Transfer Enhancement

Increasing functional requirements of electronic technology products and rapid development of micro-electronic processing technology makes the electronic devices with higher performance but smaller size which brings the contradiction between the demand of high performance and high stability of the chips and unresolved situation of high heat flux. In view of this problem, this thesis designed and manufactured a kind of heat sink with corrugated-bottom micro channels and it was tested through computer simulation and experiments. Morphology observation, pressure drop tests and forced convection heat transfer experiments of the structure were planned to study the influence of corrugated structure parameters on heat and mass transfer performance. The main contents in this thesis were as follows:(1) A kind of micro channel heat sink with corrugated bottom was designed combined micro channel structure with corrugated structure and its parameters were decided. Surface structure and morphology of micro channel heat sinks with different corrugated parameters which were manufactured by CNC milling were observed and studied.(2)ANSYS-Fluent was used to simulate the pressure drop and flow pattern in forced convection of the micro channel with corrugated bottom in the conditions of low flow velocity(0.22~1.19m/s) and low Reynolds number(150~820). To prove the conclusions, the pressure drop experiments of forced convection were tested. It is found that the corrugated bottom break the regular laminar boundary layer and reduce the pressure drop of the fluid by 40% compared to flat channels. Besides, among the corrugated parameters, interval plays an important role and amplitude can be neglected in the influence of pressure drop.(3) Through setting up the forced convection experiment system, temperature and pressure in single-phase and two-phase heat transfer tests were studied in the condition of difference inlet temperature(30℃, 60 ℃and 90℃) and low mass flow rate. Flow regime,heat transfer coefficient and its boiling curve in single phase and two phase were reported in details. Besides, heat transfer performance of micro channels with different corrugated parameters were investigated to provide reference for design of corrugated channels. Compared with the heat transfer performance of flat micro channels, it is found that corrugated bottom showed its advantages in aspects of increasing heat transfer coefficient, reducing wall temperature by 15℃, improving the critical heat flux and enhancing heat transfer performance.(4) Corrugated structure brought the regular fluctuation of temperature and pressure of inlet and outlet in two phase boiling which was not showed in the test of plat-bottom channels. Influence of effective input power, corrugated parameters and inlet temperature on the fluctuation was investigated and heat transfer performance was discussed at the same times. It is found that the amplitude and period of the fluctuation is inversely proportional to amplitude of corrugated structure and inlet temperature. Besides, heat transfer performance is enhanced in micro channel with corrugated bottom because of this phenomenon.