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《中国工程机械学报》2015,(1)
换热器管束振动的响应反问题,即根据换热管的结构特性和响应参数确定换热管所受的载荷.按照对响应处理方法的不同,可以分为时域法和频域法.在换热器寿命内,流体诱导换热器管束振动一直是工程师主要关注的问题.20世纪60年代以来,在物理学以及其他众多的科学技术领域中,提出了由输入求输出的反问题,通常称为"数学物理反问题".将换热管处理成无阻尼的、简单的欧拉梁模型.由于时域法拥有更高的识别精度,因此采用基于时域内的Newmark法直接识别换热管所受的载荷,完成载荷的识别. 相似文献
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本文采用有限元方法,分析了管壳式换热器的换热管及管束的约束对其振动固有频率的影响。通过对比分析不同管板厚度下,单个换热管前三阶固有频率的变化特性,发现换热管的固有频率随着管板厚度的增加逐渐增加。分析了GB151-1999中给出的管束的振动特性,发现管束的固有频率在解析解频率附近范围内存在较多频率。因此,在计算换热管束振动特性时,为了获得较为精确的结果,采用有限元方法计算是有必要的。 相似文献
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A louver-finned flat tube heat exchanger was tested, and the data are compared with those of the state-of-the-art round tube
heat exchanger. Both heat exchangers have the same tube perimeter and fin pitch. Tests were conducted under dry and wet condition.
Results show that, under dry condition, both j and f factors of the round tube heat exchanger are larger than those of the
flat tube heat exchanger. As the Reynolds number decreases, however, the j and f factors of the flat tube heat exchanger increase
at steeper slopes than those of the round tube heat exchanger. Under wet condition, contrary to the dry surface, both j and
f factors of the flat tube heat exchanger are larger than those of the round tube heat exchanger. Explanation is provided
considering the condensate drainage between louvers and fins. Performance evaluation was also performed. 相似文献
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介绍了常用空气热交换器的结构特点、使用效果。通过对钢管缠绕钢带式热交换器和钢管串铝箔热交换器的有关技术参数进行计算分析探讨,得出钢管串铝箔热交换器的使用效果、材料成本均优于钢管缠绕钢带式热交换器。 相似文献
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翅片管换热器是高效节能钢带式果蔬绿色干燥装备的供热装置,通过对翅片管换热器的翅化比、对流换热系数、传热系数及阻力的计算,得到了翅片管换热器的压降及翅片管的管数,计算结果表明翅片管换热器换热能力强,传热系数高。 相似文献
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Vortex generators are fabricated on the fin surface of a fin-tube heat exchanger to augment the convective heat transfer. In addition to horseshoe vortices formed naturally around the tube of the fin-tube heat exchanger, longitudinal vortices are artificially created on the fin surface by vortex generators. The purpose of this study is to investigate the local heat transfer phenomena in the fin-tube heat exchangers with and without vortex generators, and to evaluate the effect of vortices on the heat transfer enhancement. Naphthalene sublimation technique is employed to measure local mass transfer coefficients, then analogy equation between heat and mass transfer is used to calculate heat transfer coefficients. Experiments are performed for the model of fin-circular tube heat exchangers with and without vortex generators, and of fin-flat tube heat exchangers with and without vortex generators. Average heat transfer coefficients of fin-flat tube heat exchanger without vortex generator are much lower than those of fin-circular tube heat exchanger. On the other hand, fin-flat tube heat exchanger with vortex generators has much higher heat transfer value than conventional fin-circular tube heat exchanger. At the same time, pressure losses for four types of heat exchanger is measured and compared. 相似文献
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高效缠绕管式换热器的节能分析与工业应用 总被引:3,自引:1,他引:2
介绍了缠绕管式换热器的节能原理,利用工业应用实例对缠绕管式换热器的节能进行了分析,并根据工业实际情况,提出了采用缠绕管式换热器,可使工艺流程简洁、操作条件优化、大幅度降低能耗的观点。 相似文献
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预应力换热器性能的数值分析与实验研究 总被引:1,自引:0,他引:1
通过对某折流杆预应力换热器模型样机的传热工艺数值计算和进一步的结构数值计算,结合模型样机的预变形实施、控制以及实验检测技术研究,实现了一种预应力换热器设计、制造及其专利技术实施。在对折流杆换热器中变形相互约束的构件之间所产生的温差应力进行数值分析的基础上,研究了预变形量对有效缓解和协调固定管板换热器在运行中各构件(管板、壳体、管束)之间的变形约束所产生的作用。研究结果表明,合理施加的预变形量可以显著地降低管板、管子和壳体上承受的温差变形约束,预变形量可以有效地控制这类换热器的运行工况下产生的温差热应力,对于防止管子与管板连接区域的破坏,避免管子压缩失稳破坏和提高换热器壳体的承载能力都有极大的益处,从而为这类换热器的设计制造以及使用和维护,延寿技术研究开辟了一条新的途径。 相似文献