Study On The Dynamic Characteristics Of Microchannel Cooling Chip And Its Hot Spot

The heat dissipation problem of electronic devices with high heat flux has been an important factor which restricts the further development of chips.Micro-channel technology has become an effective way of cooling chips and their hot spots,due to its high heat exchange efficiency and large cooling flux.However,most of the current research on microchannel cooling chips is based on constant thermal load conditions,without considering the dynamic changes of thermal load.Therefore,the dynamic characteristics of the microchannel cooling chip and its hot spots are studied for the two-dimensional and three-dimensional chip in this thesis.In this thesis,an experimental bench for the microchannel cooling chip and its hot spot is first built,and the dynamic cooling characteristics are studied experimentally.Then,based on the transient simulation model,the dynamic characteristics of the flat microchannel cooling two-dimensional chip and its hot spot are further simulated and analyzed,and the heat dissipation of hot spot is optimized from the perspective of introducing the isothermal layer and the pin-fin structure at the hot spot.On this basis,the influence of different layouts of inlets and outlets on the multiple hot spots of the microchannel cooling chip under dynamic thermal load was studied.Finally,according to the research conclusions on the cooling of the two-dimensional chip and its hot spots,the dynamic cooling performance of the micro-channel cooling the three-dimensional chip and its hot spots is analyzed.For the research on flat microchannel cooling two-dimensional chip and its hot spot,the experimental results show that the hot spot can be reduced to 93-94℃while the pressure drop is between 27-72k Pa under the experimental conditions:inlet flow rate is between 1.04-2.25m/s,the heat flux of substrate is 9.33W/cm~2 and the heat flux of hot spot is 254W/cm~2.The dynamic simulation study shows that the peak temperature of the chip has a lag of 0.08-0.42s compared with the thermal load.The peak temperature will not only appear at the hot spot,but may also appear on the outlet side of microchannel,and the pressure drop decreases with the increase of the heat load.On this basis,a thermostatic layer is introduced first to enhance the cooling effect of hot spot,which can reduce the temperature of hot spot by 27.1%,and then pin fin is arranged to further reduce the temperature of hot spot by 14%.When cooling multi-hot spots of two-dimensional chip,Z-type microchannel is the best,which can reduce the peak temperature to the lowest,and the temperature uniformity is the best,but it will lead to a slightly higher pressure drop at low flow rate.In addition,when the microchannel cools the three-dimensional chip and its hot spots,it is found that the temperature of the top chip is the lowest,while the temperature of the bottom chip is the highest,and the maximum temperature difference between different layers can reach 7.98°C.Compared with single-layer microchannel,the flow distribution of multi-layer microchannel is relieved to a certain extent due to the increase of the collecting area.This research has certain guiding significance for the optimization design of microchannels used in cooling chip and its hotspot.