热管--一种高效实用的散热方法

任何电子器件冷却的热电路都是由3个最基本的热阻组成的:结-壳热阻Rj-c;壳-散热器热阻Rc-s和散热器至周围介质的热阻Rs-a.为降低这些热阻的临界值,许多工程师费尽心血.文章讨论采用热管有助于降低热阻Rs-a至最小值.散热器至周围介质的热阻是由传导、对流/辐射和被加热的冷却介质形成的3个热阻组成的.典型的风冷散热器中,空气温升的热阻是通风量的直接函数,对流热阻是散热表面积的函数,传导热阻是散热器材料的热导率和几何尺寸的函数.热管能把传导损耗降至最小值,它允许加大散热表面,而且使给定风速下的流量最大,从而有效降低散热器的3个主热阻.文章讨论了能降低风冷散热器热阻的热管.

Heat Pipes:A Practical and Cost Effective Method For Maximizing Heat Sink Effectiveness

A thermal circuit for the cooling of any electrical device consists of three primary resistances. These are the resistance from junction to case, Rj-c; the resistance for case to sink, Rc-s; and the resistance from sink to ambient, Rs-a. There have been many engineering man- hours spent minimizing each of these critical resistances. This paper discusses the use of heat pipes to help minimize one of these resistances, Rs-a. The sink to ambient thermal resistance is composed of three, resistances due to conduction, convection/radiation, and the heating of the cooling medium. In a typical air-cooled heat sink the resistance due to the air temperature rise is a direct function of the air flow rate. The convection resistance is a direct function of the finned surface area. The conduction resistance is a function of geometry and thermal conductivity of the heat sink material. Heat pipes can be used to minimize conduction losses allowing larger finned surface areas and higher mass flow rates for a given air velocity, effectively decreasing all three of the major heat sink thermal resistances. This paper discusses the use of heat pipes to minimize the thermal resistance of air-cooled heat sinks.