共查询到19条相似文献,搜索用时 500 毫秒
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对倾斜角为20°、24°、28°和32°的单头以及32°的双头周向重叠三分螺旋折流板换热器和弓形折流板换热器的传热和压降性能进行了测试,换热器采用公共壳体和可更换管芯结构。采用壳侧轴向雷诺数和轴向欧拉数分别作为反映壳侧流量和阻力系数的无因次参数。试验结果显示在试验范围内周向重叠三分螺旋折流板换热器壳侧换热系数、壳侧压降和综合性能指标都随着倾斜角增大而减小;倾斜角20°方案的性能指标最佳,其平均壳侧努塞尔数和轴向欧拉数与弓形折流板方案的数值之比分别为1.123和0.45;双头螺旋折流板方案的换热系数和压降都大于同样倾斜角的单头螺旋折流板方案,但两者的综合性能较接近。 相似文献
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采用由SRK方程计算得出的混合工质物性参数,将具有相变两相流体物性分三部分处理,得出混合工质分段物性数据拟合曲线,并输入FLUENT软件的材料物性数据文件中,作为数值模拟物性参数数据。在上述物性数据处理的基础上,对混合工质天然气液化装置中换热器采用分段方式进行稳态数值模拟研究,得到沿长度方向一定温度下传热系数、压力梯度的变化曲线。通过与MUSE软件数据比较,计算结果有一定合理性,所得结论为有相变换热的混合工质低温板翅式换热器的设计和优化提供一定参考。 相似文献
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Cooling technology is facing new challenges with the increase of electronic equipment power onboard aircraft. The traditional heat sink based on high-altitude bleed air does not satisfy this increase of cooling demands. In this article, an air/air-type skin heat exchanger is studied for cooling aircraft electronic equipment. It uses outside high-altitude cold air rather than bleed air as a heat sink. This cooling technology can effectively remove the heat load of high-power electronic devices without greatly increasing aircraft performance penalty. To assess its high-altitude heat transfer performance, an experimental prototype was designed and made. Some experiments were conducted on a ground experimental test. The heat transfer criteria formulas were obtained for both the side air in the skin heat exchanger and its convective heat transfer coefficients. Based on these experimental analyses, the heat transfer performances of the skin heat exchanger in a high-altitude cruise condition are deduced when it is assumed to be installed at an unfavorable position and a favorable position, separately. This work tries to provide a technical support for its future onboard application. 相似文献
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Abstract This article presents the empirical study of a heat pipe heat exchanger that was directly experiencing the ambient tropical air in its evaporator section. The performance of the heat pipe heat exchanger was monitored during two weeks of operation to determine the performance curves. The temperature of return air was controlled at about 22°C as the representative temperature of inside air, and a face velocity of 2 m/s on the heat pipe heat exchanger coil was established for this purpose. It was found that for the present investigation, the heat pipe heat exchanger can pay for itself in 1.5 years. 相似文献
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Forced convection heat transfer from a helically coiled heat exchanger embedded in a packed bed of spherical glass particles was investigated experimentally. With dry air at ambient pressure and temperature as a flowing fluid, the effect of particle size, helically coiled heat exchanger diameter, and position was studied for a wide range of Reynolds numbers. It was found that the particle diameter, the helically coiled heat exchanger diameter and position, and the air velocity are of great influence on the convective heat transfer between the helically coiled heat exchanger and air. Results indicated that the heat transfer coefficient increased with increasing the air velocity, increasing helically coiled heat exchanger diameter, and decreasing the particle size. The highest heat transfer coefficients were obtained with the packed-bed particle size of 16 mm and heat exchanger coil diameter of 9.525 mm (1/4 inch) at a Reynolds number range of 1,536 to 4,134 for all used coil positions in the conducted tests. A dimensionless correlation was proposed for Nusselt number as a function of Reynolds number, particle size, coil size, and coil position. 相似文献
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本文基于热量流法,应用进口温差定义的换热器通用热阻,采用分段法考虑超临界CO2的物性变化,结合能量守恒方程,构建了超临界CO2-冷却水换热过程的整体热量流拓扑模型,结合超临界CO2物性库和经验关联式提出了换热器性能分析的流程图,实现了综合考虑物性-结构-运行参数的超临界CO2-冷却水换热器的性能分析,进一步结合[火积]耗散热阻的概念提出了评价物性变化时换热器换热性能的等效热阻。通过分析获得了换热量的沿程分布规律,发现当进口压力为11 MPa时,总的换热量最大,此时等效热阻最小。总之,热量流法对超临界CO2为工质的换热器设计和系统分析是可行和有效的。 相似文献