Heat pipe is always bent in the typical application of electronic heat dissipation at high heat flux,which greatly affects its heat transfer performance. The capillary limit of heat transport in the bent micro-grooved...Heat pipe is always bent in the typical application of electronic heat dissipation at high heat flux,which greatly affects its heat transfer performance. The capillary limit of heat transport in the bent micro-grooved heat pipes was analyzed in the vapor pressure drop,the liquid pressure drop and the interaction of the vapor with wick fluid. The bent heat pipes were fabricated and tested from the bending angle,the bending position and the bending radius. The results show that temperature difference and thermal resistance increase while the heat transfer capacity of the heat pipe decreases,with the increase of the bending angles and the bending position closer to the vapor section. However,the effects of bending radius can be ignored. The result agrees well with the predicted equations.展开更多
This article made experimental study on mini-axial grooved heat pipes (AGHP) with 11 flattening forms. It analyzed how the flattening form, flattening thickness and working temperature affect axial temperature distrib...This article made experimental study on mini-axial grooved heat pipes (AGHP) with 11 flattening forms. It analyzed how the flattening form, flattening thickness and working temperature affect axial temperature distribution, thermal resistance, heat transfer limit and the phase-change heat transfer coefficients in evaporator and condenser sections. The result indicates that all forms of AGHPs can maintain good isothermal performance under normal operating condition. The geometric shape of AGHP has obvious impact on heat transfer limit. With respect to an AGHP with 2 mm-thick evaporator section, when the thickness of its condenser section increases from 2 to 3 mm, its heat transfer limit increases by 81%; with respect to an AGHP with 3 mm-thick evaporator section, when the thickness of its con- denser section increases from 2 to 3 mm, its heat transfer limit increases by 134%; with respect to an AGHP with 4 mm-thick condenser section, when the thickness of its evaporator section increases from 2 to 3 mm, its heat transfer limit increases by 26%. When the thickness of the evaporator section in- creases by 1 mm, the heat transfer limit will increase by 9%―26%, while when the thickness of the condenser section increases by 1 mm, the heat transfer limit will increase by 20%―86%. The thickness of the condenser section has greater impact on heat transfer performance of an AGHP than the thickness of the evaporator section does. The study content of this article will help understand the heat transfer performance of AGHP, and electronic thermal design process.展开更多
目的当整条电缆线路被敷设时,由于环境的变化引起部分电缆段热阻高于周围环境介质的区域,导致处于此区电缆段导体温度也高于线路中剩余缆段,从而影响整条电缆的载流量下降。方法根据电缆周围环境介质热特性不同,分析穿过不利散热区时的...目的当整条电缆线路被敷设时,由于环境的变化引起部分电缆段热阻高于周围环境介质的区域,导致处于此区电缆段导体温度也高于线路中剩余缆段,从而影响整条电缆的载流量下降。方法根据电缆周围环境介质热特性不同,分析穿过不利散热区时的电缆同时产生径向和轴向热流,利用调和平均法对电缆薄层处理,从而建立和简化不利散热区的三维离散热路模型,修正外热阻计算参数;基于IEC60287电缆载流量计算的基础上,迭代计算三维热场中电缆的稳态载流量。结果通过对单回路三根型号YJV8.7/10k V 1×300电缆的仿真计算,得到电缆轴向导体温度分布曲线和两个温度区域的排管敷设交联聚乙烯电缆的载流量。结果显示电缆稳态时载流量降低达40%以上。结论穿过不利散热区的电缆轴向温度和载流量的计算分析,为电力部门相关工作人员确定电缆载流量提供了参考数据。展开更多
基金Project(U0834002) supported by the Joint Funds of the National Nature Science Foundation of China and Guangdong ProvinceProject (2009ZM0134) supported by the Foundational Research Funds for the Central Universities in China
文摘Heat pipe is always bent in the typical application of electronic heat dissipation at high heat flux,which greatly affects its heat transfer performance. The capillary limit of heat transport in the bent micro-grooved heat pipes was analyzed in the vapor pressure drop,the liquid pressure drop and the interaction of the vapor with wick fluid. The bent heat pipes were fabricated and tested from the bending angle,the bending position and the bending radius. The results show that temperature difference and thermal resistance increase while the heat transfer capacity of the heat pipe decreases,with the increase of the bending angles and the bending position closer to the vapor section. However,the effects of bending radius can be ignored. The result agrees well with the predicted equations.
文摘This article made experimental study on mini-axial grooved heat pipes (AGHP) with 11 flattening forms. It analyzed how the flattening form, flattening thickness and working temperature affect axial temperature distribution, thermal resistance, heat transfer limit and the phase-change heat transfer coefficients in evaporator and condenser sections. The result indicates that all forms of AGHPs can maintain good isothermal performance under normal operating condition. The geometric shape of AGHP has obvious impact on heat transfer limit. With respect to an AGHP with 2 mm-thick evaporator section, when the thickness of its condenser section increases from 2 to 3 mm, its heat transfer limit increases by 81%; with respect to an AGHP with 3 mm-thick evaporator section, when the thickness of its con- denser section increases from 2 to 3 mm, its heat transfer limit increases by 134%; with respect to an AGHP with 4 mm-thick condenser section, when the thickness of its evaporator section increases from 2 to 3 mm, its heat transfer limit increases by 26%. When the thickness of the evaporator section in- creases by 1 mm, the heat transfer limit will increase by 9%―26%, while when the thickness of the condenser section increases by 1 mm, the heat transfer limit will increase by 20%―86%. The thickness of the condenser section has greater impact on heat transfer performance of an AGHP than the thickness of the evaporator section does. The study content of this article will help understand the heat transfer performance of AGHP, and electronic thermal design process.
文摘目的当整条电缆线路被敷设时,由于环境的变化引起部分电缆段热阻高于周围环境介质的区域,导致处于此区电缆段导体温度也高于线路中剩余缆段,从而影响整条电缆的载流量下降。方法根据电缆周围环境介质热特性不同,分析穿过不利散热区时的电缆同时产生径向和轴向热流,利用调和平均法对电缆薄层处理,从而建立和简化不利散热区的三维离散热路模型,修正外热阻计算参数;基于IEC60287电缆载流量计算的基础上,迭代计算三维热场中电缆的稳态载流量。结果通过对单回路三根型号YJV8.7/10k V 1×300电缆的仿真计算,得到电缆轴向导体温度分布曲线和两个温度区域的排管敷设交联聚乙烯电缆的载流量。结果显示电缆稳态时载流量降低达40%以上。结论穿过不利散热区的电缆轴向温度和载流量的计算分析,为电力部门相关工作人员确定电缆载流量提供了参考数据。
