共查询到18条相似文献,搜索用时 140 毫秒
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为分析板翅式换热器在低温工况下的流动换热性能与常温工况下的差异和翅片节距对其性能影响,建立氦气在锯齿翅片通道内流动与传热的数值模型,开展数值模拟分析。结果表明:低温氦气在锯齿型翅片通道内的传热性能优于常温氦气。在氦气入口温度为20 K时,j因子比300 K时提升1.1%~55.9%,比77 K时提升0.41%~13.01%;在氦气入口温度为77 K时,j因子比300 K时提升0.53%~38.47%。低温氦气在锯齿型翅片通道内的流动性能比常温氦气差。在氦气入口温度为20 K时,f因子比300 K时高16.84%~28.87%,比77 K时高3.98%~23.19%。翅片节距大小在不同温区下对翅片流动与传热性能均有显著影响。在不同温区下,j因子随着翅片节距增大而减小,f因子随着翅片节距减小而增大。低雷诺数时,JF因子随着翅片节距减小而增大,而高雷诺数时则出现相反的趋势。 相似文献
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锯齿与打孔翅片表面性能数值模拟 总被引:2,自引:0,他引:2
以两种翅片表面(锯齿翅片、打孔翅片)为研究对象,采用 FLUENT 软件模拟和分析不同结构参数和数对翅片表面传热与流动阻力的影响,得出不同结构参数和操作参数下两种翅片的表面性能曲线;分别分析了锯齿翅片的翅片高度、翅片间距、翅片厚度和切开长度以及打孔翅片开孔率对翅片表面流动与传热性能影响;分析比较了两种翅片的性能. 相似文献
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《制冷与空调(北京)》2019,(8)
提出一种结构简单,可实现对流换热和辐射换热一体化的对流-辐射型墙面板换热器,建立其供热模型并进行试验验证,分析翅片高度、翅片间距和管中心距等对供热性能的影响。研究结果表明,3个结构参数对换热器供热性能均有一定影响:当翅片高度由20 mm增大到30 mm时,墙面板换热器单位面积总换热量增加11.9%;翅片间距由10 mm增大到20 mm,管中心距由30 mm增大到45 mm时,墙面板换热器单位面积换热量分别减少9.2%和4.3%。 相似文献
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对13个微通道冷凝器空气侧性能进行实验研究,分析空气侧换热系数和压降与迎面空气流速、翅片片距、百叶窗翅片开窗数、扁管宽度及扁管高度之间的关系,并将实验值与3个不同的百叶窗翅片换热及压降关联式的预测值进行比较。结果表明:翅片片距和扁管宽度对空气侧性能影响较大,3个关联式中Kim—Bullard关联式预测偏差相对最小,换热系数的预测偏差在0~-30%以内,摩擦系数的偏差在±20%偏差范围内。最后基于已有实验数据,对KimBullard关联式进行重新拟合。 相似文献
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《制冷与空调(北京)》2019,(9)
针对对流-辐射型墙面板换热器结构进行优化设计,采用j/f1/3作为综合性能评价指标,利用正交试验法模拟分析结构参数对换热性能的影响,得出墙面板换热器的优化结构。研究结果表明:当翅片高度由20 mm增大到30 mm时,空气侧换热能力的增大幅度大于压力损失的增大幅度;当管中心距由30 mm增大到45 mm时,空气侧换热能力增大而压力损失减小;当翅片间距由5 mm增大到10 mm时,空气侧换热能力的增大幅度大于压力损失的增大幅度;墙面板换热器的优化结构为翅片间距10 mm,翅片高度30 mm,管中心距45 mm。 相似文献
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采用CFD数值模拟的方法,对整体翅片式微通道换热器空气侧的流动与传热特性进行研究,用场协同的原理分析翅片参数(长度、高度、间距)对换热器性能的影响,并与传统微通道换热器空气侧性能进行对比。结果表明:在考查的翅片尺寸范围内,随着翅片长度的缩短、高度的增加、间距的减小,温度场和速度场的协同性随之改善,有利于换热效果的提高;与传统的微通道换热器相比,整体翅片式微通道换热器空气侧换热性能变差,但是阻力大大降低,总体性能有所改善。 相似文献
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针对应用于电站直接空冷凝汽器的蛇形翅片扁平单排管,对其空气侧的流动及换热特性进行了数值模拟。给出了该管件基本结构的雷诺数和欧拉数随迎面风速的变化关联式;结果显示,同一迎面风速下,随着翅片间距、高度的增大,换热变差,流动变好。但当间距增加到一定程度时,风速与间距对换热流动性能的影响都变得很小。风速越大,换热性能对翅片间距、高度越敏感,而流动则相反,需根据实际工况来选择合适的翅片间距及高度。 相似文献
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积灰对具有不同翅片结构的翅片管换热器均会造成长效性能的衰减。本文搭建了换热器积灰可视化实验台,研究了翅片结构对积灰量及积灰后空气侧压降的影响。测试样件的翅片类型包括平直翅片、波纹翅片和开窗翅片;翅片间距范围为1.3~1.8 mm。实验结果表明:开窗翅片管换热器表面最容易沉积粉尘并增大积灰后压降,与平直翅片相比,波纹翅片和开窗翅片表面粉尘沉积量分别提高了25.6%和52.8%、积灰后压降增量分别提高了44.4%和165.6%;对于开窗翅片,小翅片间距有利于积灰并增大积灰后压降,与翅片间距1.8 mm的样件相比,翅片间距1.5 mm和1.3 mm的样件表面粉尘沉积量分别提高了26.2%和43.2%、积灰后压降增量分别提高了24.1%和49.4%;在积灰过程中,随着粉尘沉积量的增加,翅片管换热器空气侧压降先增大后保持稳定。 相似文献
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Dr. J. Albert Ackermann Liang-Eng Ong Sai C. Lau Ph.D. 《Forschung im Ingenieurwesen》1995,61(4):84-92
A computational study is conducted to examine the fully developed laminar flow and heat transfer characteristics in solar
collector panels with internal, longitudinal, corrugated fins. The fins are integrally attached to the upper and lower panel
walls. The objective of the study is to determine the effects of varying the fin pitch (or fin angle), the fin thickness,
the ratio of the thermal conductivity of the panel walls and the fin to that of the fluid, and the thermal boundary condition
on the panel heat transfer and pressure drop. The solutions of the momentum and energy equations are obtained by using a control-volume-based
finite difference algorithm. The results of the study are also applicable to the design of internally-finned channels in compact
heat exchangers. The overall panel heat transfer increases when the fin pitch (or the fin angle) is decreased, when the fin
thickness is increased, and when the thermal conductivity ratio is increased. The streamwise pressure drop increases with
decreasing fin pitch (or fin angle) and increasing fin thickness. For a fixed fin thickness, the selection of a small fin
pitch (or fin angle) over the range studied results in a higher heat transfer enhancement per unit pumping power. 相似文献
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空调器室内机多数采用翅片管换热器,会因制冷运行过程中表面析湿而粘附灰尘,导致空气流动阻力增大。本文选用空调器中常用的平直翅片、波纹翅片和开窗翅片作为测试样件,翅片间距范围为1.5~2.2 mm,研究了翅片管换热器在析湿工况下的积灰特性及积灰对空气侧压降的影响。结果表明:翅片表面的析湿量决定积灰程度,析湿液滴分布越密集、液桥数量越多,翅片迎风面的堵塞程度越严重且空气侧压降越大。在相同析湿工况下,具有复杂结构的开窗翅片和小翅片间距更容易积灰并增大空气侧压降,因此降低翅片结构复杂程度并适当增大翅片间距有利于空调器的防尘。在积灰过程中,随着换热器表面粉尘沉积量增加,空气侧压降先增大后保持稳定。 相似文献
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The laminar flow in a helically finned pipe has been considered. The steady solutions have been obtained by numerical integration of the Navier-Stokes equations formulated in a cylindrical coordinate system. Three-dimensional fins have been embedded in the structured mesh as immersed boundaries. A helical fin generates a swirling flow which exhibits a helical symmetry. In the presence of a single fin, the circumferential velocity turned out to increase both with fin height and fin angle. The core region with high axial velocity is shifted away from the pipe axis. High levels of axial vorticity caused by the fin-induced swirl are observed in the vicinity of the tip of the fin whereas substantial vorticity of opposite sign is produced in the wall-layer near the suction side of the fin. In the presence of two fins with the same pitch, i.e., a double helix, the symmetry about a diametrical plane gave rise to a keyhole-shaped axial velocity distribution. The drag coefficient was increased by all the fin configurations considered when compared to regular pipe flow at the same Reynolds number. 相似文献
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《Advanced Powder Technology》2023,34(1):103929
This study aimed to investigate the separation performance of a cyclone separator after reshaping its cylindrical body by installing the helical triangular fins. A numerical simulation based on Fluent was adopted to perform an orthogonal test to optimise the structure of the cyclone separator with helical triangular fins. Three structural parameters of the helical triangular fins were selected as optimisation variables: base width, fin size, and fin pitch, and their influences on the evaluation indices of the cut-off diameter were investigated. The optimal combination scheme was determined by range analysis, and the cyclone separator performances before and after optimisation were compared and analysed. The significant influence of the structural parameters on the cut-off diameter was in descending order as the fin pitch, fin size, and base width. For particles with diameter of 0.1, 0.5, 1, 2, and 3 μm, the separation efficiency of the cyclone separator with optimized helical triangular fins increased by 7.4 %, 15.9 %, 20.1 %, 10.9 % and 14.8 % respectively. Moreover, the cut-off diameter of the finned cyclone separator is reduced by 30.7 %, while the pressure drop is only increased by 6.6 %. The short circuit flow and back-mixing were alleviated, thereby considerably enhancing the stability of the flow field. Therefore, the finned cyclone separator was found to play a critical role in increasing the separation of fine particulate matter. 相似文献
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This article demonstrates the practical applications of a multi-objective evolutionary algorithm (MOEA) namely population-based incremental learning (PBIL) for an automated shape optimization of plate-fin heat sinks. The computational procedure of multi-objective PBIL is detailed. The design problem is posed to find heat sink shapes which minimize the junction temperature and fan pumping power while meeting predefined constraints. Three sets of shape design variables used in this study are defined as: vertical straight fins with fin height variation, oblique straight fins with steady fin heights, and oblique straight fins with fin height variation. The optimum results obtained from using the various sets of design variables are illustrated and compared. It can be said that, with this sophisticated design system, efficient and effective design of plate-fin heat sinks is achievable and the best design variables set is the oblique straight fins with fin height variation. 相似文献