核级DCS机箱设备散热性能研究及影响因素分析

Research on heat dissipation performance of nuclear DCS chassis and analysis of the influencing factors

为研究核安全级DCS机箱的散热性能和影响因素,建立起某核级DCS机箱的有限元模型,进行热学仿真分析。研究结果表明,稳定阶段U1芯片的最高温度为90℃,与实际采集温度87.9℃基本一致,所建立的有限元模型有效可靠。机箱表面温度受内部安装功能模块的影响,功能模块热功耗越高,其表面温度越大。在同一功能模块位置,机箱顶部的表面温度高于底部的表面温度。机箱在自然对流状态下,空气以“下进上出”的方式流动,且机箱顶部的空气流速大于底部的空气流速。进一步地,通过改变取热方式、通风率、进风方式、风量等因素研究对机箱散热性能的影响,结果表明:通过芯片-导热垫-翅片式壳体-机箱的取热方式散热效果最优,相比于自然散热,关键器件的表面温度降低了55.4℃。通风率与机箱散热性能呈现出正相关的关系,当机箱的通风率逐步上升时,器件温度呈现出近似线性下降的关系。当风扇安装于机箱上方进行吸风时,关键器件温度为59.8℃。相比之下,当风扇安装于机箱下方送风时,关键器件温度为63℃,故风扇安装于机箱上方为较优的选择。机箱的散热性能受风扇送风量的影响,风扇风量越大,机箱的散热性能越好。

In order to study heat dissipation performance and the influencing factors of nuclear safety DCS chassis,this paper establishes a finite element model of a nuclear DCS chassis and carries out thermal simulation analysis.The research results show that the maximum temperature of U1 chip at the stable stage is 90℃,which is basically consistent with the actual measured temperature of 87.9℃.Therefore,the finite element model established in this study is effective and reliable.The surface temperature of the chassis is influenced by the function modules installed inside.The higher the thermal power consumption of the functional modules is,the higher the surface temperature is.At the position of the same function module,the temperature at the top surface of the chassis is higher than that at the bottom surface.In the state of natural convection,air flows in from the bottom surface and out from the top surface,and the air flow velocity at the top surface is greater than that at the bottom.Furthermore,by changing heating method,ventilation rate,air intake method,air volume and other factors to study the effect on heat dissipation performance of the chassis,the results show that the best thermal transmission path starts from the chip to the thermal pad,and then the heat transfers to the finned shell and finally to the chassis.Compared with natural cooling,the surface temperature of the key components reduces by 55.4℃.There is a positive correlation between the ventilation rate and the heat dissipation performance of the chassis.When the ventilation rate of the chassis increases,the temperature of the components shows an approximately linear decline.When the fan is installed above the chassis to absorb air,the temperature of the key components is 59.8℃.In contrast,when the fan is installed below the chassis to supply air,the temperature is 63℃,so the fan installed above is a better choice.The heat dissipation performance of the chassis is affected by the airflow of the fan.The larger airflow of the fan is,the better the heat dissipation performance of the chassis is.