Study on Conjugate Heat Transfer in Electronic Equipment of Next Generation

(1)开发了用于流体流动和换热模拟的三维CFD程序。利用该CFD程序，模拟了围护结构底部小热源的导热与自然对流的耦合换热。在数值结果的基础上，提出了适用于共轭换热问题的有效换热面积的概念。该CFD程序同样适用于传导和强迫对流的共轭换热。(2)对安装在印刷电路板上的单个热源的共轭换热进行了研究。基于有效换热面积的概念，得到了努塞尔数和雷诺数之间的唯一关系式。这种关联式可以预测散热器表面的最高温度，并为电子设备的热设计估算有效换热表面积。(3)…对换热系数的影响此外，还对两种情况下的流量、热源尺寸和导热系数进行了精确的测量：一种是安装在电路板一侧的表面积为几平方厘米的热源，另一种是安装在电路板上的凸出热源。作为基准实验数据，这些结果可以帮助CFD设计者开发和评估用于电子设备热设计的新的CFD程序。(4)对安装在印刷电路板上的电子芯片模块的传热特性进行了测量。将组件封装的传热特性与安装在印制板上的简单热源进行了比较。阐明了主要的换热路径和各路径的热阻。对模拟的换热路径进行了验证研究。对换热路径模型进行了修正和改进。将CFDesign程序的模拟结果与实验数据进行了比较。阐明了CFDesign程序的局限性和准确性。(5)详细研究了多个组件封装安装在一个印刷电路板上的共轭换热特性。在此基础上，研究了组件间距、印制板导热系数和管内流量对有效换热面积的影响以及努塞尔数和雷诺数之间的关系。在上述研究的基础上，讨论了多模块封装的最优布局问题。较少

(1) 3-D CFD code for the simulation of fluid flow and heat transfer has been developed. Using this CFD code, conjugate heat transfer of conduction and natural convection from a small heat source mounted on the bottom wall of an enclosure has been simulated. Based on the numerical results, a new concept of the effective heat transfer area that is applicable to conjugate heat transfer problems has been proposed. This CFD code is also applicable to the conjugate heat transfer of conduction and forced convection.(2) Study on conjugate heat transfer of a single heat source mounted on a printed circuit board (PCB) has been carried out. Based on the concept of the effective heat transfer area, a unique correlation between Nusselt number and Reynolds number has been obtained. This correlation can predict the maximum temperature on the heat spreader surface and estimate the effective heat transfer surface area for thermal design of electronic equipment.(3) Heat transfer coefficients affected by … More the flow rate, dimensions of the heat source and thermal conductivity of PCB have been measured accurately for two cases; one for a heat source with a surface area of several square centimeters mounted on the one side of PCB, the other for a protruded heat source mounted on the PCB. As the benchmark experimental data, these results can assist CFD designer to develop and evaluate new CFD code for thermal design of electronic equipment.(4) Measurements of heat transfer characteristics of an electronic chip module mounted on the PCB have been performed. The heat transfer characteristics of a module package have been compared with a simple heat source mounted on the PCB. The main heat transfer paths and the thermal resistance of each path have been clarified. The validation of modeled heat transfer paths has been investigated. The models for heat transfer paths have been amended and improved. Simulation results obtained with the 'CFdesign' code have been compared with the present experimental data. The limitations and accuracy of 'CFdesign' code have been clarified.(5) Conjugate heat transfer characteristics for the multiple module packages mounted on a PCB have been numerically studied in details. Based on these numerical results, the effects of the interval between the module packages, thermal conductivity of PCB, and flow rate inside the duct on the effective heat transfer area and the relation between the Nusselt number and Reynolds number have been studied. Based on the above studies, the optimal arrangements of multiple module packages have been discussed. Less