浅滩毛细管前端换热器换热数值模拟研究

采用CFD模拟方法,针对埋置于浅滩中作为海水源热泵前端换热器的毛细管换热器,模拟了冬季和夏季的传热过程.结果表明,埋置于浅滩中的毛细管换热器应用于海水源热泵的前端换热换热效果较好.毛细管换热器单位席面积换热量夏季可达到125 W/m~2左右,冬季可达到100 W/m~2左右.从传热角度看,毛细管内流速取0.05~0.15m/s相对合理.     

毛细管网辐射式空调系统适用的场所

毛细管网模拟叶脉和人体毛细血管机制,由外径为3．5—5．0mm（壁厚0．9mm左右）的毛细管和外径20mm（壁厚2mm或2．3mm）的供回水主干管构成管网。冷热水由主站房供至毛细管平面末端,由毛细管平面末端向室内辐射冷热量,实现夏季供冷、冬季供热的目的。冬季采暖,则夏季可以直接利用廉价冷源直接供冷。空调系统～般由热交换器、带循环泵的分配站、温控调节系统、毛细管网（席）组成。     

温湿度独立控制空调系统在青岛香溪庭院二期别墅的应用

该项目冷热源采用地埋管地源热泵系统,末端采用毛细管席辐射系统。介绍了负荷计算、空调系统设计和运行测试结果。运行结果显示,基本达到设计要求,室内舒适度良好。     

毛细管换热器的换热特性研究

作为地表水源热泵的前端换热器,毛细管换热器具有优良的性能,对毛细管的结构优化设计研究对地表水源热泵的推广与应用具有重要意义.建立不同管间距下的毛细管换热器三维模型,搭建试验台进行换热实验来验证数值模拟的准确性.利用Fluent对毛细管换热器进行放热工况下的数值模拟,通过分析在不同地表水流速下的各个模型的进出口温差、单位席面积换热量、单位体积换热量、传热系数,来确定最佳管间距.并分析毛细管换热器换热性能指标随地表水流速的变化,研究它对毛细管换热器换热的影响.     

塑料毛细管换热器传热系数影响因素分析

毛细管席作为空调系统的辐射末端,得到逐步的重视和应用,但对于应用在闭式地表水源热泵系统中,作为地表水体的前端集热器的研究资料较少.建立毛细管简化的数学模型并通过大量数值计算,确定影响k值的各个参数,得出不同参数对k值的影响曲线,通过对影响曲线进行分析,区分出影响传热系数的主要、次要因素,对毛细管前端换热器的设计及应用提供理论基础.     

高效毛细管电泳在现代中药中的应用

高效毛细管电泳是指以高压电场为驱动力,以毛细管作为分离通道,依据样品中各组分之间淌度和分配行为上的差异而实现分离的一类液相分离技术。高效毛细管电泳一般存在六种分离模式,即毛细管区带电泳、毛细管胶束电动色谱、毛细管凝胶电泳、毛细管电色谱、毛细管等电聚焦电泳及毛细管等速电泳。通过对每种分离模式的分离特点介绍以及近年来对几种分离模式的应用情况,本文阐述了高效毛细管电泳在现代中药发展中的广阔前景。     

英国足球场站席研究及其对中国的启示——中国申办世界杯规划战略研究系列(14)

现代足球场的站席看台具有其多重优势,具有很高的实用性和推广价值。本文通过研究英国足球场站席的百年发展过程,结合文化、社会、政治等问题,从安全设计、单元划分,灵活模式三方面总结阐释英国足球场站席的特征和问题,并结合中国自身的特点,对中国未来的足球场站席发展提出启示。     

平面混凝土楼板或石膏板吊顶下毛细管网抹灰技术——毛细管网平面辐射空调技术之一

理论上,毛细管网辐射空调系统可以与各种类型的吊顶结合。从室内空气(热源)传到毛细管网栅的热量决定了冷吊顶制冷量。这就意味着,单位时间内从室内通过位于毛细管网栅和吊顶表面之间的分隔层后达到毛细管的热量才能被吸收。在毛细管网天花辐射吊顶技术中,由于吊顶的类型和冷吊     

2008年奥运会国家曲棍球A场

根据2008年奥林匹克国际夏季运动联合会要求,奥运会曲棍球比赛将在A?B两个赛场举行?这两块赛场均被规划在北京奥林匹克公园B区? 国家曲棍球B场位于A场的北侧,共设计有5 000座的临时看台及相关临时辅助用房?这些设施赛后将被拆除,以便扩大绿地空间及延伸自然景观? 国家曲棍球A场是奥林匹克体育中心B区的主要部分,占地7hm2,为奥运会曲棍球预赛及决赛场地?总建筑面积24 000m2,规模15000座席(其中8000固定座席,7 000活动座席),包括普通观众席14 000席,贵宾官员席400席,记者席300席,运动员席300席(带桌200席),残疾人52席?西侧看台为固定看台,…     

毛细管网生态空调系统在沈阳奥园国际城的应用

介绍了毛细管网辐射供冷供暖技术的原理,分析了毛细管网生态空调系统的优缺点,以及沈阳奥园国际城项目毛细管网生冬空调系统的设计和施工。对毛细管网生态空调系统的节能性、热舒适性进行了高度评价。     

湿法施工毛细管末端冬季换热性能实验研究

针对采用湿式施工法的毛细管辐射末端,在冬季工况下对其换热特性进行了实验研究,并对不同敷设面层厚度及不同管间距的毛细管辐射末端的换热性能进行了对比实验分析.研究结果表明,与传统地板辐射供暖方式相比,地面湿式毛细管末端具有较低供水温度,并有良好的冬季换热性能和系统节能性.建议在实际工程应用中,根据室内散热量与人体热舒适性的...     

排水固结法砂垫层厚度需求

排水固结法需要的砂垫层厚度一直存在争议。根据路基和大面积堆场横断面上沉降分布的特点,按照砂垫层排水能力等于地基固结排水速率的原则推导得到了不同断面形式的砂垫层对应的砂垫层水头公式和砂垫层厚度公式。研究表明,砂垫层厚度需求值与路基宽度(或盲沟间距)、主固结沉降速率、砂垫层渗透系数、砂垫层最大水头等有关。砂垫层断面形式或参数不同,水头曲线不同。相同用砂量、相同排水速率时,半凹透镜断面砂垫层水头小于其他形式断面砂垫层。工程实例表明本文方法是符合实际情况的。     

纤维网对MDF水泥基层压复合材料抗折性能影响的研究

用玻璃纤维网，铜纤维网和尼龙纤维制备了多种纤维网ＭＤＦ水在层压复合材料，由Ｉｎｓｔｒｏｎ８５０１万能材料试验机测试了这些层压复合材料的三点弯曲全荷载－挠度曲线，研究了不同纤维网对ＭＤＦ水泥基层压复合材料抗折性能的影响。     

Effects of the nuisance algae, Cladophora, on Escherichia coli at recreational beaches in Wisconsin

Recreational beaches constitute a large part of the 12 billion dollar per year tourism industry in Wisconsin. Beach closures due to microbial contamination are costly in terms of lost tourism revenue and adverse publicity for an area. Escherichia coli (E. coli), is used as an indicator of microbial contamination, as high concentrations of this organism should indicate a recent fecal contamination event that may contain other, more pathogenic, bacteria. An additional problem at many beaches in the state is the nuisance algae, Cladophora. It has been hypothesized that mats of Cladophora may harbor high concentrations of E. coli. Three beaches in Door County, WI were selected for study, based on tourist activity and amounts of algae present. Concentrations of E. coli were higher within Cladophora mats than in surrounding water. Beaches displayed an E. coli concentration gradient in water extending away from the Cladophora mats, although this was not statistically significant. Likewise, the amount of Cladophora observed on a beach did not correlate with E. coli concentrations found in routine beach monitoring samples. More work is needed to determine the impact of mats of Cladophora on beach water quality, as well as likely sources of E. coli found within the mats.     

Deformation adjustment of concrete beams laminated with carbon fiber mats

A carbon fiber mat is a sheet composed of intercrossing short carbon fibers, which has more stable and lower electrical resistivity compared with dispersed short carbon fiber mixed in cement. Thereby carbon fiber mats can be used in cement and then make cement structures exhibit obvious electro-thermal effect. In this paper, Electro-thermal properties of carbon fiber mats and an elementary strengthening experiments against deformation of carbon fiber mat cement laminated beams were researched. Firstly, electro-thermal properties of carbon fiber mats were studied. Secondly, carbon fiber mat laminated beams are designed and experiments were conducted to get temperature and deformation responses driven by the electro–thermal effects of the carbon fiber mat cement laminated beams. Finally, some experiments of deformation adjustment were done according to the above experimental results. The results show that deformation of concrete beams upon loads can be reduced even removed, and the beams can be strengthened against deformation.     

筏板抗冲切有限元分析及计算方法研究

在筏板的抗冲切设计问题中,筏板的抗冲切控制锥体和控制周长的选择是确定筏板抗冲切承载力的关键。中国相关规范中对筏板的抗冲切问题的描述比较粗略,没有考虑实际工程中各种柱(墙)对筏板的冲切状况。对筏板的抗冲切控制锥体和控制周长的选取也过于简略,只提供了几何形状较简单的矩形柱等荷载作用下筏板的抗冲切计算,无法为实际工程中遇到的各种冲切问题提供完善的解决方案。为了探索、分析上述问题,结合实际工程通过有限元软件对各种异型柱(墙)对筏板的冲切进行了模拟计算,并将计算结果与按规范JGJ 94—2008的公式计算的结果进行比较、分析。最终,在结果比较的基础上确定筏板抗冲切线的形状和位置,提出实际工程中筏板抗冲切的计算建议。     

Analytical study of beam-to-HSS/CFT column connections by trapezoidal external stiffener

Use of continuity plates in box columns is approved by design codes. To meet seismic parameters, considering performance problems and lack of confidence in the quality of the connections due to closed section, unsuitable vision and extreme welding and cutting at junction, continuity plates have been removed from the column and replaced by external stiffener. In this study, behavior of box beam-to-column connections with/without continuity plates, with external stiffener in two states with/without concrete (CFT/HSS) inside the column and finally reinforced connection by horizontal bar mats in CFT (Concrete Filled Tube) column have been studied by finite elements modeling and nonlinear analysis under monotonic and cyclic loadings. The results have shown that the use of external stiffener rather than continuity plate causes to increase 1% in rigidity and in turn 46.09% in strength. On the other hand, the use of filler concrete in column has caused to improve seismic behavior of the connection. When this connection containing the combination of external stiffeners and horizontal bar mats in CFT column is taken place, rigidity and strength parameters will be increased 3.01% and 108.8% respectively, compared to connections with no horizontal bar mats. In addition, the proposed connection has best performance in terms of both stress distribution and energy absorption and meets rigid connection criterion as well.     

Microcosm experiments of oil degradation by microbial mats

Several microcosm experiments were run in parallel to evaluate the efficiency of microbial mats for crude oil degradation as compared with physico-chemical weathering. The oils used in the experiments constituted representative examples of those currently used for commercial purposes. One was aliphatic and of low viscosity (33.4 American Petroleum Institute degrees, degrees API) and the other was predominantly aromatic, with high sulphur content (ca. 2.7%) and viscosity (16.6 degrees API). After crude oil introduction, the microcosms were kept under cyclic changes in water level to mimic coastal tidal movements. The transformations observed showed that water weathering leads to more effective and rapid elimination of low molecular weight hydrocarbons than microbial mat metabolism, e.g. n-alkanes with chain length shorter than n-pentadecane or n-heptadecane, regular isoprenoid hydrocarbons with chain length lower than C16 or C18 or lower molecular weight naphthalenes. Microbial mats preserved these hydrocarbons from volatilization and water washing. However, hydrocarbons of lower volatility such as the C24-C30 n-alkanes or containing nitrogen atoms, e.g. carbazoles, were eliminated in higher proportion by microbial mats than by water weathering. The strong differences in composition between the two oils used for the experiments were also reflected in significant differences between water weathering and microbial mat biodegradation. Higher oil viscosity seemed to hinder the former but not the later.     

Construction of an offshore dike using slurry filled geotextile mats

A study on the use of clay slurry filled geotextile mats to construct dikes for land reclamation at Tianjin Port, China, is presented in this paper. The dike so formed was covered by a thin layer of grouted geotextile mattress for protection. Through laboratory tests, a type of low plasticity clay was chosen to be the fill for the mats. A simple method for estimating the required tensile strength for the geotextile mat and the height of the mat was proposed. A preliminary design for the dike was made. Numerical analysis and centrifuge model tests were conducted to verify the design and assess the stability of the dike before construction. A field trial was also carried out in which a 100 m long and 4.8 m high dike was constructed on soft seabed. The dike has been stable and the settlement has been within the expected limit since the construction was completed in September 2001.     

The microbial domes of Wadi Muqshin pools,Sultanate of Oman

The paper reports studies on benthic microbial dome‐shaped mats found in hypersaline desert pools in Wadi Muqshin, southern Oman, and details the hydrogeological conditions of the pools, including water quality and recharge features. The upper 1 cm layers of these microbial mats are dominated by cyanobacteria, a phototrophic purple sulphur bacterium and diatoms. The dominant cyanobacterium is Microcoleus chthonoplastes and the purple layer below the upper layer is dominated by the photosynthetic sulphur bacterium Chromatium okenii. It is unusual to find standing water containing microbial domes in such a hyper‐arid, inland site which borders the Rub’ Al Khali (Empty Quarter). The flooding regime here depends largely on ‘fossil’ groundwater (Zone C, L.UER aquifer) mostly derived from the Pleistocene. Attempts to carry out desert agriculture with abstraction of this ‘fossil’ groundwater might cause the extinction of the Muqshin pools.