Research On Microchannel Liquid Cooling Design And Its Thermal Performance Of Multi-chip PCB Board

With the development of miniaturisation and integration of chips,the problem of chip heating due to increased heat flow density is becoming increasingly serious.High power multi-chip PCB with a number of high heat flow density chips scattered across the board.The problem of severe and unevenly distributed heat generation from multiple chips can cause damage to devices and equipment.So,effective heat dissipation is required for several chips at the same time.Microchannel liquid cooling technology is an efficient heat dissipation technology with good prospects for application.Therefore,micro-channel liquid cooling technology is used to solve the heat dissipation problem of a high-power multi-chip PCB board in this thesis.First,a series-parallel ladder-table micro-rib array micro-channel cold plate structure is designed and optimized.And then the thermal performance of this microchannel cold plate is focused on.The main research elements of this thesis are as follows:(1)The micro-channel cold plate structure is designed according to the thermal requirements of this multi-chip PCB board.A partial-to-whole design approach is adopted to design a forked-row micro-ribbed array structure for the core heat generation area first.By comparing the combined heat transfer performance of four different micro-ribbed arrays,the ladder-table micro-ribbed array is preferred as the heat dissipation structure for the core heat generation area.The main flow channel is then designed in series and parallel,and the flow field in the channel is distributed more evenly by providing chamfers in the channel where the flow velocity is zero.The resulting cold plate structure allows the maximum temperature to be reduced to 70 °C during multi-chip operation,with a temperature difference within 7.5 °C and a temperature standard deviation within3 °C.(2)The thermal analysis of the micro-channel cold plate of the series-parallel ladder table micro-rib array designed in this thesis was carried out by means of numerical simulation.The discussion focuses on the influence of non-geometric factors such as inlet flow rate,inlet Reynolds number,fluid working mass and solid material on the heat transfer characteristics of the cold plate under single-phase flow.In addition,the flow field characteristics in the cold plate channel is analysed in this thesis,and it has been found that fluids form vortexes and secondary flows of varying degrees in the laddertable micro-ribbed array channels,which in turn have an enhanced heat transfer effect.The rationality of the design of the cold plate structure was also verified based on field synergy theory.Finally,a coupled flow-thermal-structural analysis of the cold plate was carried out and the reliability of the cold plate structure was verified on the basis of the maximum heat deformation and thermal stress values obtained.(3)The microchannel cold plate heat dissipation experimental system is designed and the experimental platform is built.The heat dissipation and homogenisation of the cold plate at different flow rates or different heat source powers are investigated by the controlled variable method.It was concluded that when the inlet flow rate was 600 m L/min,the maximum temperature of the heat source was less than 70 ?,the temperature difference was less than 7.5 ? and the temperature standard deviation was less than 3 ?,which reached the heat dissipation index of this thesis.By analysing the experimental and theoretical values of temperature difference and temperature standard deviation,it was found to be within 6% average error,and the cold plate is proved to have excellent temperature homogeneity,and the reasons for the error of the two are analysed.