翅片管换热器与微通道换热器腐蚀对比分析

通过对铜铝翅片管换热器和微通道换热器进行腐蚀研究,本文对比分析了腐蚀对换热器形貌、传热、空气流通阻力方面的影响。结果表明,经过1 250 h腐蚀试验后,翅片管换热器主体完好,但边板处的翅片腐蚀严重并出现脱落,而微通道换热器局部区域的翅片脱离扁管,出现翅片粉化现象。腐蚀引起换热器的传热性能下降,720 h时,两种换热器的换热量衰减程度接近;1 250 h时,微通道换热量衰减程度明显大于翅片管换热器。腐蚀引起换热器的空气流通阻力增大,微通道换热器的风阻增幅明显高于翅片管换热器。     

翅片管式换热器与微通道换热器腐蚀对比分析

通过对铜铝翅片管式换热器和微通道换热器进行腐蚀研究,对比分析腐蚀对换热器形貌、传热和空气流通阻力的影响。结果表明,经过1 250 h腐蚀试验后,翅片管式换热器主体完好,但边板处的翅片腐蚀严重并出现脱落,而微通道换热器局部区域的翅片脱离扁管,出现翅片粉化现象;腐蚀引起换热器的传热性能下降,720 h时这2种换热器的换热量衰减程度接近,1 250 h时微通道换热器的换热量衰减程度明显大于翅片管式换热器;腐蚀引起换热器的空气流通阻力增大,微通道换热器的风阻增幅明显高于翅片管式换热器。     

微通道换热器中制冷剂分流均匀性的研究进展

全铝微通道换热器因其高效、低成本等优势而逐渐应用到制冷空调产品上,目前常采用集管竖直扁管水平和集管水平扁管竖直两种布置形式,不同布置形式的换热器中制冷剂分流现象有所不同,各影响因素对分流均匀性的影响程度也有所变化。本文对近年来国内外关于微通道换热器中制冷剂分流均匀性的研究文献进行总结,概述了集管竖直扁管水平和集管水平扁管竖直两种不同布置形式时的制冷剂分流特点及各影响因素对分流均匀性影响。本文能够为微通道换热器的分流优化提供设计参考,有助于分流不均问题的解决并进一步提高换热性能。     

表面处理对微通道换热器湿工况性能及长效特性的影响

对翅片间距为1.1mm的微通道换热器进行了亲水和疏水表面处理,并对其不同工况下的性能进行了实验研究,分析了表面处理对微通道换热器湿工况性能和长效特性的影响。实验表明,疏水表面处理在低风速下会造成换热器性能衰减：与原换热器相比,经过疏水表面处理的换热器换热量最大减小14%,衰减随着风速的变大而减小;而压降除了高风速高湿度工况,其余工况下均升高130%以上。亲水表面处理对换热器性能影响较小：与原换热器相比,经过亲水表面处理的换热器在不同工况下性能衰减2%-8%;压降仅在高湿度低风速下明显变大17%,其余大部分工况得到改善,在高湿度高风速下压降仅为原换热器的50%。亲水表面处理在防腐蚀方面具有一定作用,同时进行盐雾腐蚀260h后,表面亲水处理的换热器在不同工况下比原换热器性能提升4%-6%,压降降低14%-16%。     

集流管结构对微通道蒸发器流量分配均匀性影响

微通道蒸发器内制冷剂流量分配均匀性对换热器性能有着较大影响。本文在理想工况运行情况前提下,以水为流动工质,数值模拟了微通道蒸发器内流量分配特性,探讨了4种集流管形式(A型、B型、C型、D型)、不同入口速度(0.08 m/s~0.42 m/s)对换热器各扁管流量分配的影响。研究结果表明,集流管入口流速对换热器内各扁管流量分配具有较大影响,当速度从0.08 m/s增大到0.42 m/s时,换热器内流量分布从两侧高,中间低的分布转变为入口侧低,出口侧高的分布特性,且流量分配不均匀度随流速增加而显著增大;通过改变集流管结构能够在一定程度上改善流量分配特性。各扁管进口静压力分布与各扁管内流量分配具有相关性,可通过改进集流管结构保证静压力分布一致,使各扁管流量分配均匀,从而获得较好的换热性能。     

微通道换热器结构强度仿真分析技术研究

微通道换热器翅片和扁管结构特征尺寸微小,在进行结构强度有限元分析时,若按实际结构建立有限元模型势必导致网格尺寸过小,网格数量巨大,软件和硬件都无法支撑这项分析。为利用有限元分析技术分析微通道换热器的结构强度,辅助微通道换热器的研发,本文设计一种微通道换热器建模及结构强度仿真分析技术,采用弹簧等效翅片进行整体模型分析,再利用子模型分析扁管及焊缝连接处细节特征。经试验验证,仿真结果分析精度满足工程应用要求。     

球墨铸铁管表面喷锌生产线的设计

球墨铸铁管表面喷锌生产线的设计机械工业部武汉材料保护研究所（４３００３０）高志，冯常勤，肖德君，冷文元武汉食品工业学院李英采用火焰和电弧喷涂法在铸铁管外壁喷涂一层锌作牺牲阳极，能使铸铁管长期耐腐蚀。若在其表面喷涂１５０～２０Ｏｇ／ｍ２厚的锌层后，再作...     

R290微通道冷凝器性能优化及其充注量分析

采用仿真方法,以R290家用空调器用微通道冷凝器为研究对象,比较不同流路布置方案对冷凝器性能的影响,并对外形尺寸相同的微通道冷凝器与翅片管冷凝器充注比进行对比。结果表明：流程布置及各流程扁管分配对微通道冷凝器性能有较大影响,存在较优的流程数及流程扁管数;R290微通道冷凝器充注比与Ф5mm单排冷凝器充注比水平相当,经进一步结构优化后,微通道冷凝器将比小管径换热器在降低冷凝器充注比和材料成本方面具有更大的潜力和优势。     

微通道平行流换热器分配特性及优化研究

微通道平行流换热器内制冷剂分配不均是限制其进一步推广应用的原因之一,当微通道平行流换热器做蒸发器时,制冷剂在换热器入口为气液两相状态,会加剧其分布不均匀性.本文以气液两相R134a制冷剂为工质,提出一种数值仿真模型,并利用前人实验数据验证了模型可靠性.提出通过改变不同扁管在集管内突出深度以改善制冷剂分配特性的4种方案,...     

颗粒物污染室外换热器对家用空调系统性能影响研究

分别配置了采用传统铜管铝翅片换热器与采用全铝微通道换热器的1.5匹分体式家用空调,将其置于相同的大气环境中长期连续运行,测试了大气颗粒物污染的两台家用空调换热器的堵塞率和空调系统的长效性能。测试结果表明:换热器的堵塞率呈指数性增长趋势,采用管片式换热器的原机被大气颗粒物污染后制冷量衰减2.1%,功耗上升了6.2%,能效比下降了7.8%;采用微通道换热器的机组性能衰减明显高于原机,制冷量衰减了23.2%,功耗增加了34.6%,能效衰减了43.1%。相比之下微通道换热器更易受颗粒物污染的影响。     

采用微通道蒸发器的分离式热管充液率实验研究

采用微通道换热器作为分离式热管的蒸发器,在充液率为80%~150%之间进行了实验研究。实验测量了微通道蒸发器换热量、管壁温度分布及系统EER,分析了不同充液率下微通道蒸发器的工作状态,计算了蒸发器传热系数,实验结果表明:微通道蒸发器换热量随室内外温差的增大而增大,分离式热管最佳充液率为120%左右。此外,与翅片管蒸发器进行了实验对比,在换热量相当的条件下,微通道蒸发器重量减轻了45%,系统工质充注量降低了51.9%,系统EER提高了2.8%。     

微通道折叠扁管承压能力仿真分析及优化设计

折叠管作为平行流冷凝器的重要组成部分,具有良好的极限承压能力使其逐步替代传统挤压管。本文对折叠管承压能力展开机理研究、仿真及实验分析。通过实验数据拟合得到折叠管材料应力应变数值曲线,将材料参数导入ANSYS建立折叠管爆破仿真模型,此模型仿真爆破值与实验爆破值21.9 MPa相符,通过实验对比验证了模型结果可靠性。基于对折叠管的理论分析,设计一种内插翅片双片式的新型微通道折叠管,通过仿真模型分析其内外壁厚等参数对极限承压能力的影响,得出在内片壁厚0.08 mm、外片壁厚0.2 mm、19孔时综合性能最优,相比于普通微通道管,新型折叠管体积减少了35%,极限承压值增加30%。新型折叠管不仅节约材料成本,使扁管结构更加紧凑,还具有优异的极限承压性能。     

微通道换热器研究进展

从微通道换热器的发展历史出发,介绍其制造方式、结构和材料,重点介绍对微通道换热器发展和降低成本有重要影响的全铝微通道管材成形加工技术。对微通道传热的特征进行述评,从微电子微机械高效传热、CO2制冷减少温室气体排放和提高家用空调能效比几个方面展现微通道换热器的应用前景。     

Development of compact heat exchangers for CO2 air-conditioning systems

Compact and lightweight heat exchangers are needed for motor vehicle air-conditioning systems and for several types of unitary equipment. The high-pressure natural refrigerant CO₂ is now being evaluated for use in such applications, and efficient heat exchangers are being developed and investigated. Carbon dioxide heat exchangers are designed for high refrigerant mass flux and use small-diameter tubes or extruded flat microchannel tubes. Refrigerant-side heat transfer coefficients are higher than with fluorocarbons, and reduced internal surface areas can therefore be tolerated. Both small-diameter mechanically expanded round-tube heat exchangers and brazed microchannel-type units have been built and tested successfully. Results show that compact heat exchangers optimized for CO₂ are very competitive with baseline HFC/HCFC units in terms of physical dimensions, exchanger mass and thermal performance. Smaller tube and manifold dimensions can give reduced size compared with HFC-134a equipment. The temperature approach between air inlet and refrigerant outlet is much lower in CO₂ gas coolers than in baseline system condensers of equal size and capacity, and the reduced refrigerant exit temperature has a marked influence on the coefficient of performance, Microchannel heat exchangers give the best overall efficiency. Refrigerant distribution in multiport manifolds and heat transfer tubes does not seem to be a problem.     

Characterization of Corrosion Products in RTPF and All-Aluminum Microchannel Heat Exchangers

Phases and morphology of corrosion products formed on failed round tube and plate fin (RTPF) and all-aluminum microchannel heat exchangers are characterized. RTPF heat exchanger experiences formicary corrosion or ant nest corrosion due to interaction with carboxylic compounds. Scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR) are used to determine different compounds formed on infinite loop copper RTPF heat exchanger. Complex compounds of zinc carbonate hydroxide, cupric oxide, cuprous oxides were also found on RTPF heat exchanger. SEM/EDS and FTIR analyses have been done on all-aluminum microchannel heat exchanger to document morphological and elemental analyses of corrosion products.     

叶脉型微通道热沉设计及散热特性分析

为改善相控阵天线多热源阵面温度的均匀性,基于植物叶脉优良的传质特性,提出一种用于相控阵多热源阵面的叶脉型微通道热沉。首先,对叶脉型微通道热沉的流动特性和散热特性进行仿真分析,得到热沉的热源温度分布。然后,以热源温度标准差最小化为目标,进一步优化叶脉型微通道结构,得到了非对称叶脉型微通道拓扑结构。最后,采用金属3D打印加工了铝基微通道热沉样件并进行散热性能测试。数值仿真结果表明,相比于传统平行微通道热沉,叶脉型微通道热沉不仅强化了传热,而且使得热源温度更均匀,压力损失更小;实验结果验证了叶脉型微通道热沉优良的散热性能。研究结论可为相控阵多热源阵面的热沉设计提供依据。     

Design and analysis of multiple parallel-pass condensers

This paper describes and analyzes a novel design of multiple parallel-pass (MPP) microchannel tube condenser and its applications to automotive A/C systems. A flow distributor concept is introduced in MPP condenser in order to enable parallel flow arrangement in adjacent flow paths. Throughout analysis of two-phase flow and heat transfer processes in MPP condenser, a two-phase zone enlargement technique is developed to enhance condensation heat transfer and reduce pressure drop. Visual observation indicates a more uniform refrigerant quality entering the next cooling pass can be achieved in MPP condenser because superheated vapor through a pass-through hole on flow distributor directly injects into the separated liquid–vapor zone in a header tube. Performance test results show MPP condenser is able to improve heat transfer rate as high as 9.5% while its refrigerant mass flow increases 13.34% when comparing to a benchmark PF condenser.     

微通道换热器两相分配特性对空调系统性能的影响

微通道换热器作为新一代换热器逐渐被使用在家电领域,其结霜、除尘、排水、分液等都是目前亟待解决的问题。通过R22家用空调系统的标准性能实验台,对三种流程数不同的微通道换热器用作冷凝器和蒸发器时,温度分布均匀性和其对系统性能的影响进行实验,研究发现,微通道换热器在用作冷凝器和蒸发器时,温度分布不均对系统性能的影响分别达到7.3%和3.5%,并且流程数对于温度分布均匀性的影响在作为冷凝器和蒸发器时是不同的。     

应用于高热流冷却的微通道实验装置的研究

本文详细介绍了微通道热沉实验装置的发展状态。建成了一个具有多功能、低不确定度、高精度温度控制的实验装置 ,用于模拟微通道热沉的实际热流状态和分析其热传导特性。最终测试实验借助于HP5 5 2 9A动态校准仪在恒温室中完成。测试结果表明 ,这个装置不仅有高的冷却效果 ,而且能满足微电子机械和纳米技术所需要的高精度温度的要求。     

Experimental investigation on the thermodynamic performance of double-row liquid–vapor separation microchannel condenser

A double-row liquid–vapor separation microchannel condenser (D-LSMC) was presented, and its tube pass scheme was optimized using the theoretical method. A series of experiments were conducted to investigate the heat load, average heat transfer coefficient (AHTC), and pressure drop of the optimal D-LSMC. Experimental results were compared with an optimal common double-row parallel-flow microchannel condenser (D-PFMC). The findings showed that, at the inlet mass flux of 585 kgm⁻² s⁻¹ to 874 kgm⁻² s⁻¹, the AHTC of the D-LSMC was 3.3%–14.4% higher than that of the D-PFMC. However, the pressure drop of the D-LSMC was only 43.4%–52.1% of that of the D-PFMC. The heat exchange capacity of the back row was weaker by almost half of that of the front row. In addition, the tube wall temperature of the back row decreased faster than that of the front row, which indicated that the back row had a larger pressure drop. The minimum entropy generation number (Ns) was used to evaluate the D-LSMC and the D-PFMC, which indicated the greater thermodynamic performance of the D-LSMC.