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挤压-犁削外翅片铜管加工机理的研究 总被引:12,自引:0,他引:12
本文对挤压-犁削外翅片铜管的加工机理进行了系统研究,着重分析了外翅片的形成过程及条作,并建立了数学模型。理论分析及试验结果表明,外翅片的形成包括挤起、切开及成翅三个阶段,只有当顶刃切出的翅片体积大于或等于刀具挤压面挤起金属鼓包的体积时,外翅片的形成过程才能连续进行,翅片形状主要取决于挤区-犁削用量及刀具几何参数。 相似文献
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建立了双面犁法加工整体翅片管的成形数学模型,推导了翅片结构参数与加工用量及刀具几何参数之间的关系,为优选翅片结构参数以达到最佳传热效果提供了理论依据。理论分析和试验结果均表明,对于某一刀具,翅片高度和平均翅厚均随挤压浓度和进给量的增加而增大。 相似文献
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百叶窗翅片管式换热器是车用换热器主要选型之一,其结构对空气侧强化传热作用有着极其重要的影响。本文总结了近几年来国内外在百叶窗翅片管式换热器的结构参数对空气侧强化传热影响方面的研究,包括翅片间距、管排数、翅片高度、百叶窗开窗角度、翅片厚度及翅片形状对空气侧换热系数、压降的影响。最后,在百叶窗结构的基础上,提出了在翅片上打孔形成百叶型多孔翅片来进一步强化空气侧换热的建议。 相似文献
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H形鳍片管传热性能的三维数值模拟计算 总被引:1,自引:0,他引:1
建立了H形鳍片管的三维物理模型,对鳍片管传热机理进行分析.利用大型通用有限元分析软件ANSYS的FLOTRAN模块,建立了热流耦合的有限元模型,对鳍片管的稳态传热过程进行了数值计算,得到了鳍片管内、外流体的温度场分布.在对鳍片高度和鳍片间距进行调整的基础上分析了高度和间距对换热效率的影响,提出了在此边界条件下对鳍片管优化的方案. 相似文献
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内螺纹翅片铜管高速旋压拉伸成形的研究 总被引:4,自引:1,他引:4
对内螺纹理片铜管的高速旋压拉伸成形加工机理进行了系统研究,分析了加工过程及参数。试验结果表明,齿深量随坯管与内螺纹管壁厚的比值及材料塑性的增加而逐渐增大,但外表面粗糙度随之变差;拉速与旋速的比值增大会导致外表面粗糙度变差,但随着旋速提高,其影响变小。 相似文献
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A general distributed model with a non-steady-state heat exchanger model coupled with a frost model was developed to study
the dynamic behavior of an airside heat exchanger in an air-to-water heat pump heater/chiller unit. The effects of water vapor
diffusion and uneven fin temperature distribution were considered. The model was found to agree well with reported experimental
results. Compared with the routine model, the present model has higher precision of frost layer thickness especially on the
fin surface. Results include the propagation of frost formation along the tube and its effect on the dynamic characteristics
of refrigerant, air, and tube sides. According to the results, the temperature difference between air and tube surface temperature
was proposed to be the main driving force of frosting. Tube surface temperature is the most important factor affecting frosting
when there is little variation in air humidity. Frost at the fin base was found to be thicker than that at the fin tip due
to the fact that the frost layer grows faster with lower tube surface temperature. 相似文献
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叠片式翅片管空气冷却器是一种高效、紧凑的空气换热高备。对新开发的第二代波纹型叠片进行了传热及阻力性能的测试,获得了一系列试验工况下的传热和管外空气流动阻力数据,通过计算得出了管外换热准则关系式和空气流动阻力准则关系式,并与第一代平片型叠片的试验结果进行对比。结果表明,两种翅化比的波纹型叠片在常规换热工况下的传热性能相当,但比平片型叠片均提高了约9%;当翅化比相同时波纹型叠片的空气流动阻力比平片型叠片增大18%左右,但适当改小翅化比后,波纹型叠片在传热性能不降低的情况下,空气流动阻力可降低至仅比平片型叠片大2.5%左右。 相似文献
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研究了平片圆管表面,开缝片圆管和开缝片椭圆管表面的流动和换热特性。翅片表面的缝为辐射布置,下游布置较多的缝。椭圆管的长短轴之比为2.25,与圆管具有相同的周长。研究结果表明,两种开缝片的换热量远大于平片,椭圆管开缝片的压降低于圆管开缝表面。在泵功消耗减少2.5%时,椭圆管开缝的换热量比圆管开缝高7%。椭圆管虽不能改善温度梯度和速度场的协同,然而压降远低于圆管开缝片,使其具有较好的综合特性。 相似文献
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为了优化结霜工况下翅片管式空气冷却器的结构设计,提出经济性分析计算模型。综合考虑换热性能、材料成本及运行费用,以单位制冷量的费用年值为目标函数,以费用年值最小为优化目标求解经济模型得到合理的空气冷却器的结构参数,分析了翅片间距、换热管管径、管排数变化对目标函数的影响,并通过一冷库案例进行实际测试验证。计算及试验结果表明:随着翅片间距的增大,目标函数先减小后增大,翅片间距为10时目标函数取极小值;在相同翅片间距的情况下管径越大,其目标函数值也越大;综合考虑换热管直径、翅片间距和管排数的影响,翅片间距为10,换热管外径为9.52,管排数为6时,目标函数取极小值。 相似文献
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Nae-Hyun Kim Jung-Ho Ham Jin-Pyo Cho 《Journal of Mechanical Science and Technology》2008,22(3):545-555
The heat transfer and friction characteristics of fin-and-tube heat exchangers having herringbone wave fins were experimentally
investigated. Eighteen samples having different fin pitches (1.34 mm to 2.54 mm) and tube rows (one to four) were tested.
For all the samples, the waffle depth and the corrugation angle of the fin was 1.14 mm and 11.7o respectively. Results showed that the j factors were insensitive to fin pitch, while f factors increased as the fin pitch
increased. As the number of tube rows increased, both the j and f factors decreased. However, the effect of tube row diminished
as the Reynolds number increased, at least for j factors. Existing correlations failed to adequately predict the present data.
A new correlation was developed based on existing data, which significantly improved the predictions of the present data. 相似文献