Performance analyses of a novel finned parabolic trough receiver with inner tube for solar cascade heat collection

Designing highly-efficient parabolic trough receiver(PTR)contributes to promoting solar thermal utilization and alleviating energy crisis and environmental problems.A novel finned PTR with inner tube(FPTR-IT),which can provide different grades of thermal energy with two heat transfer fluids(oil and water),is designed to improve thermal efficiency.In this FPTR-IT,an inner tube and straight fins are employed to respectively lessen heat loss at upper and lower parts of the absorber.Based on the design,a numerical model is developed to investigate its performance.Comparisons with other PTRs indicate that the FPTR-IT can combine the advantages of PTR with inner tube and finned PTR and obtain the best performance.Moreover,performance evaluation under broad ranges of direct normal irradiances(300–1000 W/m^(2)),flow rates(50–250 L/min)and inlet temperatures(400–600 K)of oil as well as flow rates(3.6–10 L/min)and inlet temperatures(298.15–318.15 K)of water is investigated.Compared with conventional PTR,heat loss is reduced by 20.7%–63.2%and total efficiency is improved by 0.03%–4.27%.Furthermore,the proportions of heat gains for water and oil are located in 8.3%–73.9%and-12.0%–64.3%,while their temperature gains are located in 11.6–37.9 K and-1.2–19.6 K,respectively.Thus,the proposed FPTR-IT may have a promising application prospect in remote arid areas or islands to provide different grades of heat for electricity and freshwater production.

Viscous Inner and Outer Pressure Forming Method of Thin-walled Tube and Its Application

Aiming at overcoming the difficulties in integral forming of thin-walled tubes with complex shapes, a novel forming method by inner and outer pressure through viscous was proposed. In this method, by dividing large deformation of the part into inner and outer pressure forming deformations, the limit deformation of tube part can be increased by several times. Meanwhile, the principle of viscous inner and outer pressure forming was provided, and key problems during the forming process such as reduction of the wall-thickness and instability wrinkling were analyzed. Thereby, the complex curved surface super-alloy GH3044 thin-walled tube with varying diameter ratio of 1.35（the ratio between the maximum and minimum diameters of the part） can be integrally formed by this method. The experimental surface of the formed part is superior in quality and the wall-thickness distribution is uniform. The results show that the viscous inner and outer pressure forming can provide a new approach for integral forming of thin-walled tubes with complex shapes.

AN INNER-FEEDBACK-STYLE TRAVELING-WAVE TUBE OSCILLATOR

A new concept of inner-feedback-style traveling wave tube oscillator, which is based on a traveling-wave tube having a partial reflector located at near the junction between the slow-wave structure and the output coupler and a mechanical tuner connected to the input coupler, is proposed. Simulations by CHIPIC code show that the inner-feedback-style traveling wave tube oscillator having 100W of power, about 10% of electron efficiency and a tunable band of 73.35-73.91 GHz may be achieved. Compared with Backward Wave Oscillators (BWOs), the new devices have similar ability for tuning, and have much higher electron efficiency, suggesting much more potential as a Terahertz source.

Extended Anode Effect for Tube Inner Coating of Non-Conductive Ceramics by Pulsed Coaxial Magnetron Plasma

For uniform tube inner coating of non-conductive thin films, the double-ended coaxial magnetron pulsed plasma (DCMPP) method was investigated. In this study, coating of TiN and TiO2 was performed. It was clearly shown that the extended anode effect was strongly influenced by the electric resistance of the coated thin films on the inner surface of an insulator tube. Additionally, high frequency (100 kHz) was better for relatively high plasma density. On the other hand, in the case of titanium oxide deposition, negative ion productions drastically decrease the deposition rate and the shifting velocity of plasma main position for coated TiO2 films.

Influences of the inner diameter of the solid shielding tube on the characteristics of the radio-frequency cold atmospheric plasma jet

Active control of the local environment of the cold atmospheric plasma(CAP) jet is of great importance in actual applications since the CAP operates in an open atmosphere with the inevitable entrainment of the surrounding cold air. In this paper, the solid shielding effects of the cylindrical quartz tubes with different inner diameters on the characteristics of the CAP jets driven by a radio-frequency(RF) power supply are studied experimentally. The experimental results show that the total length of the shielded plasma jet can be increased significantly by an appropriate combination of the quartz tube inner diameter and that of the plasma generator nozzle exit with other parameters being unchanged. This phenomenon may be qualitatively attributed to the loss of diffusion of the charged particles in the radial direction under different inner diameters of the quartz tubes. Compared with the plasma free jet, the plasma shielding jet is produced with optimized parameters including longer plasma jet length, higher concentrations of chemically reactive species, higher rotational, vibrational, and electron excitation temperatures when the inner diameters of the solid shielding tube and the generator nozzle exit are the same. A maximum plasma jet length of 52.0 cm is obtained in contrast to that of 5.0 cm of the plasma free jet in this study. The experimental results indicate that the solid shielding effect provides a new method for the active control of the local environment of the RF-CAP jet operating in an open atmosphere.

Response features of nonlinear circumferential guided wave on early damage in inner layer of a composite circular tube

A theoretical model to analyze the nonlinear circumferential guided wave(CGW) propagation in a composite circular tube(CCT) is established. The response features of nonlinear CGWs to early damage [denoted by variations in third-order elastic constants(TOECs)] in an inner layer of CCT are investigated. On the basis of the modal expansion approach, the second-harmonic field of primary CGW propagation can be assumed to be a linear sum of a series of double-frequency CGW(DFCGW) modes. The quantitative relationship of DFCGW mode versus the relative changes in the inner layer TOECs is then investigated. It is found that the changes in the inner layer TOECs of CCT will obviously affect the driving source of DFCGW mode and its modal expansion coefficient, which is intrinsically able to influence the efficiency of cumulative second-harmonic generation(SHG) by primary CGW propagation. Theoretical analyses and numerical simulations demonstrate that the second harmonic of primary CGW is monotonic and very sensitive to the changes in the inner layer TOECs of CCT, while the linear properties of primary CGW propagation almost remain unchanged. Our results provide a potential application for accurately characterizing the level of early damage in the inner layer of CCT through the efficiency of cumulative SHG by primary CGW propagation.

充分利用隧道窑热量同步焙烧煤矸石轻集料技术研究

主要介绍了充分利用隧道窑热量同步焙烧煤矸石轻集料技术及节能焙烧设备的研究情况,依据以内螺旋筒为特征结构的节能焙烧工作原理,研究、设计、试制了实验炉模拟设备,并以辽源市煤矸石为原料进行了相关焙烧试验,验证了其所形成的煤矸石轻集料焙烧新工艺。模拟实验表明,利用隧道窑热量(余热)同步焙烧煤矸石轻集料技术具有可行性。

内套GFRP管圆钢管混凝土组合柱的偏压力学性能分析

利用ABAQUS有限元软件建立了适用于内套GFRP管圆钢管混凝土组合柱的单向偏压模型,研究了影响该组合柱力学性能及失效模式的关键因素。结果表明:该组合柱的极限承载力随着偏心距的增大而降低,随着外置圆钢管和内套GFRP管壁厚的增加而提高。内套GFRP管壁厚对构件极限承载力的影响小于偏心距和外置圆钢管壁厚造成的影响。长径比对极限承载力的影响较小。基于影响系数法建立了适用于单向偏压构件的极限承载力计算方法,该计算方法可为相关工程提供参考。

基于液压内胎硫化机的硫化飞边原因分析及控制措施

基于液压内胎硫化机的结构特点,分析造成内胎硫化飞边问题的原因,并提出相应的控制措施。通过采取准确计算硫化机合模力、检验新模具质量、控制模具预热变形、加强模具清洗和存放管理工作、将硫化机的空心热板更换为加厚的实心热板及将导向机构由工字型滚轮/铁板导轨更换为直线滑轨/滑块等措施,大幅降低了内胎硫化飞边出现的频率,为内胎硫化飞边问题提供设备检修流程的理论依据。

内壁喷丸设备在锅炉行业中的应用研究

本文首先阐述了不锈钢管内壁进行喷丸强化处理必要性,然后就公司引进开发了两条不锈钢管内壁喷丸强化处理生产线设备的工艺规范、质量要求、设备选型、设备组成、工作流程及控制和注意事项进行分析。

一种埋地电缆管道内切割装置的研制

针对目前10kV及以上埋地电缆保护管的切割待解决的问题,从传统的切割工具、切割方式的基础上研制了一款电缆保护管内切割装置。本款埋地电缆管道内切割装置采用半自动环绕管内壁切割的方式,结合其装置前后两端的固定结构完成切割工作,内切割装置的使用能有效解决电缆保护管端面切割不整齐的问题,最大限度地发挥了保护管的功能,提高了埋地敷设的施工质量。

Computational fluid dynamic simulation of an inter-phasing pulse tube cooler

An inter-phasing pulse tube cooler (IPPTC) consists of two pulse tube units, which are connected to each other at hot ends of the pulse tubes through a needle valve. This paper presents the computational fluid dynamic (CFD) results of an IPPTC using a 2D axis-symmetrical model. General results such as the phase difference between pressure and velocity at cold end and hot end, the temperature profiles along the wall, the available lowest temperature as well as its oscillations and the coefficient of performance (COP) for IPPTC are presented. The formation of DC flow and its effects on the performance of the cooler are investigated and analyzed in detail. Turbulence, which is partially responsible for the poor overall performance of a single orifice pulse tube cooler (OPTC), is found to be much reduced in IPPTC and its performance is improved significantly compared with the single OPTC.

General issues of FEM in backward ball spinning of thin-walled tubular part with longitudinal inner ribs

Backward ball spinning was applied for manufacturing thin-walled tubular parts with longitudinal inner ribs. Rigid-plastic finite element method(FEM) was used for simulating the backward ball spinning process in order to calculate the height of the inner ribs. With a view to guarantee a better simulation accuracy, it is essential to enhance and improve some general problems of FEM, such as generation of initial velocity field, choice of penalty factor, determination of boundary conditions, treatment of rigid region and description of convergence criteria. It is evident that whether the problems with respect to FEM are dealt with appropriately or not, they have a significant influence on the modeling accuracy and efficiency. By reasonable solving the general problems, rigid-plastic FEM can successfully simulate the height of the inner ribs and the calculated values are in good agreement with the measured values.

内壁强化对TA16钛合金传热管断裂韧度的影响

采用TA16传热管制备的直流蒸汽发生器是新一代核动力装置的核心部件。为提高管材的内壁质量,目前采用内绞、喷砂等数道表面加工程序,生产成本大幅升高。为简化工艺流程,降低生产成本,开展针对TA16管材的内壁强化技术研究。同时为了确定内壁强化对管材断裂韧性的影响,提出一种含双边轴向裂纹管(DEAT)试样,通过弹塑性有限元分析建立DEAT试样的应力强度因子K和J积分的计算表达式,通过建立的试验方法完成内壁强化前后TA16传热管的J-R曲线测试,获得内壁强化前后TA16传热管的断裂韧性参数。试验后采用SEM、EBSD、TEM及纳米压痕分析内壁强化对管材微观组织和性能的影响。研究结果表明:强化后TA16管内壁从表面沿径向形成100~200μm的纳米超细晶区和孪晶变形区,显著提高了管材的内壁质量,但由于表层的硬度升高,导致传热管的断裂韧度整体水平有所下降。研究结果可为TA16管材的质量提升、安全性评价及性能退化评估奠定技术基础。

偏心钢梁-钢管混凝土柱内加强环式节点受力性能分析

建立了钢管混凝土内加强环式节点的ABAQUS有限元模型,通过参数分析考察了偏心对节点刚度和承载力性能的影响。在刚度方面,分别考察了偏心对节点连接刚度和节点剪切刚度的影响。在节点承载力方面,在有限元分析结果的基础上选取了较为合理的计算理论,并通过理论推导对其进行了考虑偏心影响的计算方法修正,同时在节点偏心的基础上进一步考虑了加强环厚度、加强环宽度、梁轴线夹角和节点区钢管壁厚4个参数的影响,并通过回归分析在计算理论中纳入了影响较大的参数。

工作气压对管内壁沉积Si/O-DLC薄膜结构与性能的影响

目的探讨工作气压对管内等离子体放电光学现象以及Si/O-DLC(Si and O Incorporated DLC,Si/O-DLC)薄膜结构与性能的影响,为获得管内高质量、均匀的Si/O-DLC薄膜制备工艺技术提供指导。方法利用空心阴极等离子体增强化学气相沉积(Hollow Cathode Plasma Enhanced Chemical Vapor Deposition,HC-PECVD)技术,通过改变工作气压在管内沉积Si/O-DLC薄膜。利用高速摄像机记录并对比不同工作气压下管内等离子体放电光学现象。通过SPM、XPS和Raman光谱仪表征不同工作气压下薄膜的三维立体表面形貌和微观结构,并利用SEM、纳米压痕仪以及划痕测试系统,对比研究管内Si/O-DLC薄膜的硬度、弹性模量、膜基结合力以及沿管轴向的薄膜厚度分布。结果随着工作气压的上升,管径向中心处亮斑面积和光强先增大增强后趋于缩小暗淡。在不同工作气压下,均能够在管内获得表面光滑的Si/O-DLC薄膜,粗糙度为3~10 nm。随着工作气压的上升,管内Si/O-DLC薄膜的平均厚度从1.42μm增大到2.06μm,且沿管轴向的薄膜厚度分布均匀度从24%显著提高到65%;不同工作气压下管内Si/O-DLC薄膜沿管轴向平均硬度呈先增大后减小的趋势,总体平均硬度可达(14±1)GPa。管内Si/O-DLC薄膜在工作气压上升到25 mTorr时获得较高的平均膜基结合力。结论改变工作气压能够显著影响管内壁Si/O-DLC薄膜的结构与性能,当工作气压为25 m Torr时,在管内获得均匀性最优、结合力较高的Si/O-DLC薄膜。

基于PSO-ELM的316L不锈钢细长管磁粒研磨内表面粗糙度预测模型

针对316L不锈钢细长管磁粒研磨加工过程中,最佳工艺参数难以选择,以及加工后对工件内表面粗糙度(Ra)的预测问题,将影响磁粒研磨316L不锈钢细长管内表面粗糙度的四个工艺参数作为输入值,内表面粗糙度作为输出值,构建粒子群(PSO)优化极限学习机(ELM)模型来预测316L不锈钢细长管内表面粗糙度,利用PSO对工艺参数进行全局寻优,获得最佳工艺参数组合,最后通过试验与预测结果进行对比。构建的PSO-ELM表面粗糙度预测模型拟合优度R2为0.9848,绝对误差(MAE)为0.0134,均方根误差(RMSE)为0.0214。得到的最佳工艺参数组合为:主轴转速2389.011r/min,进给速度3.167 mm/s,磨料粒径216.185μm,加工时间35.856 min,预测Ra为0.178μm。对工艺参数进行调整,试验得到的Ra为0.182μm,与预测值相比误差为2.24%。基于PSO-ELM方法构建316L不锈钢细长管内表面粗糙度预测模型,实现对工件内表面粗糙度的精确预测,应用粒子群方法得到最佳工艺参数组合,提高了磁粒研磨316L不锈钢细长管的加工效率。

中深层深井换热器实验测试及传热特性模拟研究

中深层地热能现已成为地热能开发利用的重点内容。文章基于实验测试,得到初始土壤温度分布及深井换热器进、出口温度变化情况,分析了中深层地热热泵供暖系统的供热特性。开发了一种二维深井换热器传热模型,考虑了实测地温梯度以及井底流动与传热过程,具有较高的计算精度。依据模型研究了内管管长,循环流量及管内流向对深井换热器传热特性的影响。结果表明:深井换热器内管管长由1890 m增至1950 m时,其取热能力增加2%~7%;循环流量为11.25~56.25 m^(3)/h时,深井换热器取热量随循环流量的增加先升高再降低,同深度处内管与环腔流体温差随循环流量的升高而降低,流体随埋深的温度变化率随循环流量的升高而降低;深井换热器环腔进水内管出水比内管进水环腔出水时取热性能更优但其热短路现象更为严重。

隔热内管对中深层地热井同轴换热器换热性能的影响

中深层地热井同轴换热器作为地下换热系统的重要组成部分,其性能优劣直接决定了地热能开发效率和取热效果。通过现场试验和数值模拟,研究了隔热内管与中深层地热井同轴换热器换热性能的关系并分析了内管隔热长度和隔热方案对同轴换热器出水温度和取热功率的影响。结果表明,将导热系数为0.06W/(m·K)的真空气凝胶隔热钢管作为内管时,同轴换热器短期取热功率为1506.83kW。对于3500m深的地热井,内管隔热性能要求随井深增加而降低,0~1400m段的隔热性能对整体换热效果影响较大,增大管内流量可减小内管有效隔热长度。

10m长管道内壁类金刚石薄膜沉积及性能

工业生产过程中管道内壁经常受到输送物质的腐蚀和磨损,对管道内壁进行涂层防护十分必要,而目前鲜有在大长径比管道内壁镀膜的报道,且缺乏对大长径比管道内壁膜层性能的研究。采用等离子体增强化学气相沉积(PECVD)技术在直径100 mm、长10 m管道内壁沉积类金刚石(DLC)薄膜,并研究管道内工作气体的等离子体放电辉光光谱、膜层表面亮度、水静态接触角、硬度、摩擦因数和拉曼光谱等。结果表明:管道内等离子体光谱显示管内等离子体中有Ar^(+)和乙炔分解成的C_(2)、H和CH;膜层表面的亮度L*最高达到37.4和色差ΔE^(*)最大1.9,膜层拉曼光谱结果表明靠近管道两端和中间位置膜层的I_(D)/I_(G)均匀,膜层水静态接触角显示靠近管道两端的膜层接触角略小;靠近管道两端膜层硬度相比中间位置的膜层硬度高,并且磨损测试中膜层均未出现破损剥落,膜层具有高的耐磨性。试验实现了在大长径比的管道内壁沉积耐磨损的DLC膜层,为长管道内壁均匀镀膜提供了理论支持和技术指导。