高压板翅式换热器偏流分析及改造

介绍42500 m~3/h空分设备高压板翅式换热器的工艺流程和参数,叙述运行过程中发生偏流的原因。通过吹扫和管路改造,解决了高压板翅式换热器偏流和温差大的问题,氧气产量也达到了设计产量。     

高压板翅式换热器冰堵的分析和预防

高压板翅式换热器冰堵现象,在煤化工空分设备中较为常见,其主要原因为空气增压机或膨胀机增压端冷却器冷却水泄漏。针对58000 m3/h内压缩流程空分设备高压板翅式换热器空气通道冰堵的故障现象,进行了详细分析,提出了相应的临时措施。     

内压缩流程空分设备高压板翅式换热器空气通道堵塞的分析

介绍了15000m3/h内压缩流程空分设备高压板翅式换热器空气通道被冰堵的故障现象,详细分析了故障原因,并阐述了查找过程和处理措施。     

高压板翅式换热器氧通道堵塞原因分析和处理

华鲁恒升KDON-48000/45500型空分设备按计划停车检修再开车后,出现了高压板翅式换热器氧通道因珠光砂堵塞而阻力上升故障。在设备停车后对高压板翅式换热器氧通道进行反吹以消除阻力,使高压板翅式换热器正常运行。文章简介了高压板翅式换热器流程、故障经过以及故障带来的负面影响,叙述了处理措施和取得的效果。     

高压板翅式换热器的设计开发

随着空分行业和石油化工行业的快速发展,中、高压板翅式换热器需求日趋增多,应用范围日趋广泛。文章主要就高压板翅式换热器的发展、结构、设计计算方法、特点及应用前景作了简单介绍。     

LNG工程用大截面高压板翅式换热器的技术发展与现状

随着国内外LNG工业的高速发展,对铝制板翅式换热器提出了新的要求,以往小截面、多只并/串连的板翅式换热器组合方案已不能满足大、中型液化天然气工业发展的需要。大截面高压板翅式换热器的换热单元个数少,承压能力高,能够尽量减少气流分配的不均性。大截面高压板翅式换热器的应用,也使得LNG冷箱内管道布置简单,安全性、可靠性大大提高,冷箱体积减小,满足了液化天然气工业发展的需要,也降低了用户投资成本。简介板翅式换热器的技术发展与现状,阐述大截面高压板翅式换热器的热力设计与结构优化。     

28000m~3/h空分设备高压换热器堵塞的原因分析与处理

介绍28000m3/h内压缩流程空分设备高压板翅式换热器堵塞后的运行工况,对堵塞原因进行分析。通过单独加温高压换热器和增设便携式露点分析仪,消除了因空气增压机段间冷却器泄漏对空分设备稳定运行造成的影响。     

杭氧高压板翅式换热器打破国外垄断

正近日,由杭州杭氧股份有限公司研制的两台设计压力为12.8MPa的高压板翅式换热器,完成最终水压为16.7MPa的压力试验,表明我国高压板翅式换热器研发取得历史性突破,打破了国外企业在10MPa及以上等级高压板翅式换热器产品的技术垄断。杭氧研发的高压铝制板翅式换热器与传统高压、低压分别制造的两台换热器的结构相比,可以减少导流片的排布和管道的连接,具有高效、节能、降低产品阻力、缩小产品外形尺寸、减小设备     

带增压透平膨胀的可逆式换热器空分流程探讨

本文就可逆式换热器的空分设备的更新设计、节能改造提出了一种带增压透平膨胀系统的新颖流程。着重探讨了1000、6000、10000Nm~3/h氧的带可逆式换热器的空分设备,采用该流程进行设计或改造的可行性,以及实施后带来的经济效益——氧提取率分别可提高4.7%、6.5%、7.9%,单位能耗可分别下降10%、4.07%、5.33%。图4表2参3。     

“6000”空分设备局部工艺改造介绍

简述了首钢氧气厂国产老6000m~3/h空分设备存在的问题,针对性地进行了板翅式换热器逐步技术改造,将小板翅式改成大截面长板翅式,并将G型切换阀改成切换蝶阀,空压机冷却器铝芯改铜芯。从改造前后效果比较来看,效果明显,启动时间缩短,氧产量增加。     

Air-side performance evaluation of three types of heat exchangers in dry,wet and periodic frosting conditions

The performances of three types of heat exchangers that use the louver fin geometry: (1) parallel flow parallel fin with extruded flat tubes heat exchanger (PF²), (2) parallel flow serpentine fin with extruded flat tubes heat exchanger (PFSF) and (3) round tube wave plate fin heat exchanger (RTPF) have been experimentally studied under dry, wet and frost conditions and results are presented. The parameters quantified include air-side pressure drop, water retention on the surface of the heat exchanger, capacity and overall heat transfer coefficient for air face velocity 0.9, 2 and 3 m/s, air humidity 70% and 80% and different orientations. The performances of three types of heat exchanger are compared and the results obtained are presented. The condensate drainage behavior of the air-side surface of these three heat exchanger types was studied using both the dip testing method and wind tunnel experiment.     

高压液空节流阀管道振动分析及优化设计

某内压缩流程空分更改高压液空节流阀流向后,先后出现了高压板式换热器液空出口管管嘴根部断裂。文章结合空分运行的实际情况,对高压液空节流阀前管道分别进行了静态和动态分析,并根据综合分析的结果,提出了一些相应的方法和措施。对于目前工程应用中还存在的一些问题进行分析与探讨,提出对空分中高压液空管道的优化设计方法,从而避免今后类似事故的再次发生。     

风机盘管换热器遗传算法优化设计

本研究采用了基于遗传算法和耗散理论的传热优化方法,并进行了风机盘管换热器的优化设计。在对板翅管式结构的风机盘管换热器进行建模的基础上,针对两种不同的应用工况,即供冷用干式风机盘管换热器和供暖型风机盘管换热器,进行了结构优化设计和分析。优化目标选取了换热器的耗散热阻,而设计变量分别选取管间距、排间距、换热管外径、翅片间距和翅片数。为评价换热器的性能,还计算了换热器的换热量、空气侧和水侧阻力损失、总泵功和换热器效能。优化设计结果显示,在特定的设计参数和限制条件下,不仅换热器的耗散热阻值降低,其他方面性能也得到了明显提升。     

干盘管用平行流换热器翅片参数对空气侧换热系数及压降的影响

为了使平行流换热器在干盘管中得到推广应用,本文根据传热及压降关联式,采用数值模拟计算的方法,研究了干盘管用平行流换热器翅片参数对其空气侧换热性能及压降的影响,为干盘管用平行流换热器的设计提供参考依据。     

Heat transfer characteristics of flat plate finned-tube heat exchangers with large fin pitch

The objective of this study is to provide experimental data that can be used in the optimal design of flat plate finned-tube heat exchangers with large fin pitch. In this study, 22 heat exchangers were tested with a variation of fin pitch, number of tube row, and tube alignment. The air-side heat transfer coefficient decreased with a reduction of the fin pitch and an increase of the number of tube row. The reduction in the heat transfer coefficient of the four-row heat exchanger coil was approximately 10% as the fin pitch decreased from 15.0 to 7.5 mm over the Reynolds number range of 500–900 that was calculated based on the tube diameter. For all fin pitches, the heat transfer coefficient decreased as the number of tube row increased from 1 to 4. The staggered tube alignment improved heat transfer performance more than 10% compared to the inline tube alignment. A heat transfer correlation was developed from the measured data for flat plate finned-tubes with large fin pitch. The correlation yielded good predictions of the measured data with mean deviations of 3.8 and 6.2% for the inline and staggered tube alignment, respectively.     

Effect of fin spacing on the heat transfer and pressure drop of a two-row plate fin and tube heat exchanger

The analogy between heat and mass transfer (using the naphthalene sublimation technique to measure the mass transfer coefficient) was used to investigate the heat transfer capabilities of various two-row plate fin and tube heat exchanger configurations. Average transfer coefficients were determined from measurements of the mass transferred in an analogical system consisting of a pair of naphthalene plates and an array of spacer discs. The analogical system modelled a typical heat exchanger flow passage. Special attention was given to the effect of fin spacing on heat transfer capabilities. A physical interpretation of the experimental data has been given and new conclusions have been drawn. The pressure drop of the heat exchanger configurations has also been investigated.     

Performance optimization of a miniature Joule–Thomson cryocooler using numerical model

The performance of a miniature Joule–Thomson cryocooler depends on the effectiveness of the heat exchanger. The heat exchanger used in such cryocooler is Hampson-type recuperative heat exchanger. The design of the efficient heat exchanger is crucial for the optimum performance of the cryocooler.In the present work, the heat exchanger is numerically simulated for the steady state conditions and the results are validated against the experimental data available from the literature. The area correction factor is identified for the calculation of effective heat transfer area which takes into account the effect of helical geometry. In order to get an optimum performance of the cryocoolers, operating parameters like mass flow rate, pressure and design parameters like heat exchanger length, helical diameter of coil, fin dimensions, fin density have to be identified. The present work systematically addresses this aspect of design for miniature J–T cryocooler.     

Air-side heat transfer enhancement of a refrigerator evaporator using vortex generation

In most domestic and commercial refrigeration systems, frost forms on the air-side surface of the air-to-refrigerant heat exchanger. Frost-tolerant designs typically employ a large fin spacing in order to delay the need for a defrost cycle. Unfortunately, this approach does not allow for a very high air-side heat transfer coefficient, and the performance of these heat exchangers is often air-side limited. Longitudinal vortex generation is a proven and effective technique for thinning the thermal boundary layer and enhancing heat transfer, but its efficacy in a frosting environment is essentially unknown. In this study, an array of delta-wing vortex generators is applied to a plain-fin-and-tube heat exchanger with a fin spacing of 8.5 mm. Heat transfer and pressure drop performance are measured to determine the effectiveness of the vortex generator under frosting conditions. For air-side Reynolds numbers between 500 and 1300, the air-side thermal resistance is reduced by 35–42% when vortex generation is used. Correspondingly, the heat transfer coefficient is observed to range from 33 to 53 W m⁻² K⁻¹ for the enhanced heat exchanger and from 18 to 26 W m⁻² K⁻¹ for the baseline heat exchanger.     

整体翅片式微通道换热器的数值模拟

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。     

一种新型板式换热器

介绍一种区别于传统人字形波纹板式换热器的新型微板换热器,该换热器具有压降小而换热能力强,材料消耗少,可靠性好,制冷剂充注量小,设计灵活等特点,同时介绍其在应用和节能减排上的优势。